How did hydrophilic plants become established on an isolated island with an arid coastal zone?

How did hydrophilic plants become established on an isolated island with an arid coastal zone?

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I find unconvincing the existing explanation of how several hydrophilic endemic plants became established at St Helena. This is one of the most isolated islands in the world, has an arid semi-desert coastline and moist and humid highlands where endemic hydrophilic plants grow. It has been suggested that plants originally arrived either as driftwood from the beaches or arrived inland because occasional birds accidentally blown to the island had seeds on their foliage or claws. However, not only would the brushwood of these hydrophilic plants be unlikely to propagate or survive the arid conditions of the coastal region, these plants normally propagate by root, not by seed.

Has the following third mechanism ever been suggested for the establishment of plants on an isolated island? I wonder whether brushwood fortuitously arrived at the point where streams were discharging into the sea. Despite the arid conditions at all other coastal regions, some plants could take root at these wet beach areas and then spread along the streams growing in the damp alluvial soil into the interior heights of the island. I know the migration of plants along the length of a stream or river (riparian zones) have been studied but I can find no reference to the idea that this can also explain the presence of hydrophilic plants in damp highland regions of an island with a surrounding arid coastal region.

How did hydrophilic plants become established on an isolated island with an arid coastal zone? - Biology

N.T. Baguinon, M.O. Quimado and G.J. Francisco
University of the Philippines, Los Baños
Forest Management Bureau, Department of Environment and Natural Resources (DENR)

The natural forest types of the Philippines

The types of forests in the Philippines were first enumerated by Whitford (1911) who recognized mangrove, beach, dipterocarp, molave, pine, montane and mossy forest types. The Palawan Botanical Expedition by Hilleshog AB (1984) recognized within Palawan many types of vegetation, for example, ultramafic and ultrabasic forests, karst limestone forests, riverine forests, semi-evergreen dipterocarp forests, evergreen dipterocarp forests and lake-margin forests. There could be more actual forest types than the number already published. Stereotyping a continuum of unique forest ecosystems into just a few lists may not render justice to the wonders of evolution and the complex Philippine bio-geological history.

However, the latest classification of Philippine ecosystem diversity types in the terrestrial setting (DENR-NBSAP 1997) are the following: (1) lowland evergreen rain forest, (2) lower montane forest, (3) upper montane forest, (4) subalpine forest, (5) pine forest, (6) forest over limestone, (7) forest over ultrabasic soils, (8) semi-deciduous forest, and (9) beach forest.

The lowland evergreen rain forests are located on volcanic soils with even distribution of rainfall and correspond with Whitford’s dipterocarp forests excluding the apitong-lauan subtype, which corresponds with semi-deciduous forest. The importance of the members of the Dipterocarpaceae is most notable in lowland evergreen rain forests (Newman et al , 1996).

Beyond 1000 metres in altitude, lower montane forests are encountered. In these forests, Fagaceae (the family of oaks) increase in number of species, as do species in families such as Araliaceae, Staphyleaceae, and Lauraceae. Many tree ferns, epiphytes such as orchids, ferns and allies, increase in importance. As elevation is gained, upper montane forest begins to occur (at about 2000 metres). Members of the Ericaceae (e.g. Rhododendron quadrasianum , Vaccinium myrtoides , etc.), Myrtaceae (such as Leptospermum flavescens ) and Theaceae (such as Eurya , Cleyera , Schima , Adinandra , and Camellia species) families are encountered (Merrill and Merritt, 1910).

In regions with seasonal monsoon climates, the montane forests when disturbed into a gap by fire is readily succeeded by disclimax vegetation dominated by benguet pine ( Pinus insularis ) (Kowal, 1975). In Mindoro Island, only tapulau pine forest exists. Pine forests are perpetuated by fire and therefore also known as fire disclimaxes.

In limestone forests, below 1000 metres, the keystone species are molave ( Vitex parviflora ), lingo-lingo ( Viticipremna philippinensis ), alagao ( Premna odorata ), and batete ( Kingiodendron alternifolium ).

Beach forests above the intertidal zone vary depending upon the substrate (Merrill, 1945). Beach forests exist as Casuarina subtype or Barringtonia subtype. In one extreme, on sand dunes, pure stands of agoho ( Casuarina equisetifolia ) would be characteristic. At the other extreme, on rocky shores, is mixed vegetation of the Barringtonia subtype.

Forests on ultrabasic soils (Hilleshog Forestry AB, 1984) are not as dense and tall as the mixed dipterocarp forests, simply because they develop on unhealthy serpentine and basic soils. This type of forest features hardwoods such as mancono ( Xanthostemon verdugonianum ), bagoadlau ( X. philippinensis ), malabayabas ( Tristaniopsis decorticata ), Brackenridgea palustris , mountain agoho ( Gymnostoma rumphiana ), and Scaevola micrantha .

The introduction of exotic species

Merrill’s " Enumeration of Philippine flowering plants " (1921-26) and subsequent revisions in the " Flora Malesiana " (1954-present) are good references to determine which species are indigenous and exotic (Rojo, 1999). Exotic species are indicated with asterisks.

Prehistoric introduction of trees (probably by Malayo-Polynesian settlers) were first noted and may have included common agricultural tree crops such as the katurai (* Sesbania grandiflora ), malunggai (* Moringa oleifera ), mango (* Mangifera indica ), nangka (* Artocarpus heterophyllus ), breadfruit (* A. altilis ), santol (* Sandoricum koetjape ), rambutan (* Nephelium lappaceum ), karamai (* Cicca (Phyllanthus) acida ), bignai (* Antidesma bunius ), kamias (* Averrhoa bilimbi ), balimbing (* A. carambola ), duhat (* Syzygium jambolana ) and other * Syzygium spp., kawayan kiling (* Bambusa vulgaris ), kawayan tinik (* B. spinosa ) and many others. Most of these are Indo-Malayan in origin. A few escaped into the wild like the bignai, duhat and santol. However, these have not grown and established themselves as persistent gregarious stands.

The Spanish regime, through the Acapulco trade, brought additional exotic tree species, mostly agricultural crops such as the * Anona spp. (atis, cherimoya, guyabano, anonas), biriba (* Rollinia deliciosa ), zapote (* Diospyros digyna) , cacao (* Theobroma cacao ), siniguelas (* Spondias purpurea ), chico (* Manilkara sapota ) , tiesa (* Pouteria campechiana ), cashew (* Anacardium occidentale ), avocado (* Persea americana ), kamatchile (* Pithecellobium dulce ) and datiles (* Muntingia calabura ). Woody trees such as the monkey-pod tree (* Samanea saman ), *ipil-ipil ( Leucaena leucocephala ), kakawate (* Gliricidia sepium ) and kalachuchi (* Plumiera rubra ) were also introduced. Coffee (* Coffea spp.) was introduced by the Spanish from Africa. Some of these escaped into the field, for example ipil-ipil, datiles, and kamatchile. Of the tropical American exotic trees, ipil-ipil may be singled-out as bio-invasive, as the species forms pure stands in open areas. Kamatchile and datiles have been dispersed but their numbers are limited, compared with ipil-ipil.

During the American regime, more exotic tree species found their way to the Philippines as Caguioa (1953) recounts:

" After the Spanish-American war, plants have been introduced into the Philippines generally by exchange between the governments of foreign countries and the Philippine Government, through the Bureau of Forestry and Bureau of Plant Industry and by purchase from foreign countries by private citizens. Introduced plants came into the Philippines during the Spanish regime, the Philippines introduced plant materials from Central American countries through missionaries and others who came to the Philippines by way of galleon from Mexico to the Orient, and from the neighbouring countries or islands through traders and travellers who came to visit this country by water transportation. During the first half of the present century, many countries in both the western and the eastern hemisphere have exchanged planting materials with the Philippines. "

Exotic species were added as a result of the agricultural and forestry schools that were opened (Buenaventura, 1958). In 1910, the School of Forestry site consisted of grass and brush at the base of Mount Makiling. Laguna, Luzon and American administrators initiated the reforestation of the school grounds mainly by planting indigenous tree species, as well as the tropical American species mahogany (* Swietenia spp.), rubber (* Hevea brasiliensis ), and ipil-ipil (* Leucaena leucocephala ). Then other exotics followed such as kakawate, palosanto (* Triplaris cumingiana ), Anchoan dilaw (* Cassia spectabilis ), golden shower (* C. fistula ), and teak (* Tectona grandis ). Note that they also introduced dipterocarps from other parts of the country to enrich the native Makiling dipterocarps, namely, white lauan ( Shorea contorta ), bagtikan ( Parashorea malaanonan ) and guijo ( Shorea guiso ) (Brown, 1919). African tulip (* Spathodea campanulata ) was introduced in 1925 to the Forestry School campus (Anonymous, 1930) and it has since spread deep in natural stands.

Ponce (1933) documented the introduction of the American mahoganies. Small leaf mahogany (* Swietenia mahogani ) was introduced as early as 1911, and by batches in 1913, 1914, 1920 and 1922, from tropical America. Large leaf mahogany (* S. macrophylla ) was first planted in Manila in 1907, then at the Forestry School at Mt. Makiling in 1913. Lizardo (1960) reviewed the introduction of Eucalyptus in the Philippines. Spanish friars introduced (* Eucalyptus globulus ) at Alcala, Cagayan as early as 1851 and in 1939, the first trial plantings for * E. robusta were initiated. Other plantings were * E. rostrata in 1918, * E. tereticornis 1910, * E. citriodora 1936, * E. viminalis 1918, * E. pulverulenta 1916, and * E. saligna 1947. The paper mulberry (* Broussonetia papyrifera ) was introduced in 1935 to augment bast fibre-producing tree crops at the Makiling Forestry School campus and - as did coronitas (* Lantana camara ) from Hawaii - escaped to become serious pests. Both species invade young secondary forests, thickets, orchards and farms. These two species and mahogany have spread throughout the Philippine archipelago.

Post-war introduction of exotics continues and planting them has almost become synonymous with reforestation. Yemane (* Gmelina arborea ) was introduced in 1960 and planted in Minglanilla, Cebu by the Bureau of Forestry (Binua and Arias, 1966). Mangium (* Acacia mangium ) was introduced in 1960 from Sabah. The Philippines Forestry Statistics (1984) record that out of a total 52 487 seedlings produced by the Philippines Government forest agency, 82.4 percent (43 234 seedlings) of seedlings were exotics. These were distributed across giant ipil-ipil (41 percent), large leaf mahogany (33 percent), yemane (17 percent), teak (4 percent), and others (5 percent). Seedlings of indigenous tree species contributed 17.6 percent.

Current foresters’ notion of reforestation

Based on the forest definition by American mentors as artificial or natural, Tamesis and Sulit (1937) define "reforestation" as the restoration of an area to forest either by artificial or natural means and "afforestation" applies to the planting of a forest on land that has not previously borne forest. They mention planting exotics in Bukidnon including chinchona, large leaf mahogany, * Araucaria bidwillii , * Pinus massoniana , Anchoan dilaw, * Adenanthera microsperma , * Thuja orientalis , black wattle (* Acacia decurrens ), and * Cryptomeria japonica . In Baguio, * Eucalyptus spp. and Alder (* Alnus spp.) were planted. Tamesis and Sulit cite that good reforestation species are of:

rapid growth for short cutting cycle

fire and other damage causes are resisted by species and

easy to grow and propagate.

There is also the mindset among foresters that artificial forests are as ecological as the natural forest they replace. For example, Domingo (1983) wrote during the First ASEAN Congress,

". .. when we convert a dipterocarp forest to pulpwood plantation, what we are doing is just transferring the jungle regrowth onto a tree species of our choice for pulpwood. Substituting the economically unnecessary but ecologically necessary jungle regrowth with an economically important pulpwood plantation does not change, it might even enhance, the normal ecological pattern. The same ecological benefits that the jungle regrowth provides can be provided by the plantation . "

In short, this goes in line with most foresters’ pragmatism that if the natural forest is gone or nearly gone, enrichment planting with fast-growing commercial exotic tree species is better than restoring natural forests for two reasons. One, because a return of investment at the earliest possible time is provided by the artificial forest, and two, artificial forests also provide the same environmental services as natural forests, particularly, on watershed function and carbon-sequestration. Other foresters also claim that analogue forests and agroforest zones can also be as rich in floral diversity as or even richer than are natural forest ecosystems. Thus, during the ASEAN Regional Centre for Biodiversity Conservation (ARCBC) Symposium-Workshop on Facing the Challenge of Sustaining Biodiversity Conservation in Mt. Makiling, Gruezo (2000) reports

". Comparison of floral diversity in these four zones (Mossy forest zone, Dipterocarp mid-montane forest zone, Grassland zone and Agroforestry Zone) reveals that the agroforestry zone had the highest diversity value using the Shannon-Weiner formula, with H’ = 4.2869 followed by the dipterocarp-mid-montane forest zone, H’ = 3.8913, . ".

Man can cram many exotic crops including their exotic weeds in one place, then make statements to the effect that agro-ecosystems are more diverse than natural forest ecosystems.

Bio-invasive species and natural forests

As far back as the pre-war period, exotic trees have been used in reforestation. Projects of the Reforestation Administration used exotic species as showcases, e.g. reforestation at Minglanilla in Cebu, the Nasiping Reforestation Project in Cagayan, Paraiso reforestation in Ilocos Norte, Canlaon reforestation in Negros, and Impalutao reforestation in Bukidnon. The reforestation projects of the Bureau of Forestry were well spread throughout the archipelago. Seedlings from these projects found their way into national parks and for this reason mahogany can be found in most of the country’s nature parks. However, no studies have yet been done on the rate of bio-invasion of these nature reserves and parks. The planting of exotics in the Integrated Protected Area System (IPAS) of the Philippines has now been prohibited under the present DENR’s PAWB (Park and Wildlife Bureau). No definite policies are in place yet on what to do with mature exotic trees, should they become bio-invasive. This issue is now being seriously considered by the College of Forestry and Natural Resources, for the Makiling Forest reserve.

Because there was a law requiring replanting of logged-over dipterocarp forests during the 1960s to 1980s, many timberlands have had been reforested with exotic trees, among them mahogany, yemane, mangium, bagras and teak. Of these tree species, only mahogany is a potential bio-invasive species in the logged-over forest and is threatening to out compete the indigenous dipterocarp and non-dipterocarp tree species.

Mahogany is successful at invading natural forests due to the following attributes of the species. The fruit of mahogany is a capsule and contains an average of 62 winged seeds (Anonymous, 1930). The number of seeds a mahogany mother tree can disperse is considerable. Assuming 50 capsules, 3000 seeds can be blown away from the mother tree. The seeds can be blown some 20 to 40 meters from the mother tree. The seeds, being recalcitrant, germinate in less than a month. Mahogany seeds contain food reserves and germinate hypogeal. This means that even if the initial light is relatively poor, the young mahogany plant develops even without initial photosynthesis. The first young leaves of mahogany are scale leaves and not green. True photosynthetic leaves come later and are adapted to sun-flecked shade and partial shade. Hardened mahogany seedlings can tolerate open fields as long as soil moisture is not limiting. The leaves of mahogany are rarely attacked by herbivores. Thus, a mahogany plantation is like a "green desert" to wildlife. Dipterocarps fruit and seed irregularly in intervals of four to five years and therefore stand no chance competing with mahogany.

When mother trees shed their leaves during the months of February, they form a thick litter mat. Dry mahogany leaves are red and can be very rich in tannin. The leaves are intact during the whole length of the dry season. This litter mat could be one reason why very few seedlings are recruited under the mahogany plantation, including their own seedlings. Dispersed recalcitrant seeds rest on top of the litter mat instead of reaching the moist soil and hence die due to desiccation.

They may also be allelopathic (Thinley, 2002). Extracts from the leaves of mahogany were shown to retard the growth of narra ( Pterocarpus indicus ) test seedlings. Recruits increase away from the mahogany plantation and this increase is proportional to the competition offered by mahogany wildlings (Alvarez, 2001 Castillo, 2001). The importance of mahogany seedlings is negatively correlated with the Shannon-Weiner Diversity Indices of quadrats positioned from the mahogany plantation and away from it. In other words, diversity of the quadrats decreases as the importance of mahogany increases.

While mahogany invades regenerating dipterocarp forests and may give the dipterocarps a hard time in competition, the paper mulberry (* Broussonetia papyrifera ) also gives indigenous gap and pioneer tree species very keen competition. Ocular observation shows that where paper mulberry forms pure stand thickets, the usual indigenous pioneer tree species such as anabiong ( Trema orientalis ), binunga ( Macaranga tanarius ), alim ( Melanolepis multiglandulosus ), banato ( Mallotus philippinensis ), tibig ( Ficus nota ), hauili ( F. septica ), isis ( F. ulmifolia ), sablot ( Litsea sebifera ), paguringon ( Cratoxylon sumatranum ), and malapapaya ( Polyscias nodosa ) are not present.

The combination of mahogany and paper mulberry is therefore a big blow for the ecological succession of the landscape, at the gap and building-up phases. This can be a serious problem for Assisted Natural Regeneration (ANR) practitioners. Other important bio-invasive species in the general landscape of rural Philippine settings are hagonoy (* Chromolaena odorata ) and coronitas (* Lantana camara ). These two species retard the succession process in open grasslands, where they can become very gregarious, thus offering no ground for indigenous gap species. Where paper mulberry cannot establish, the equally important bio-invasive species ipil-ipil (* Leucaena leucocephala ) can usurp steep bare slopes and form pure stands of ipil-ipil. At the back of beaches and along beaches, two exotic mimosoid legumes also form gregarious thickets of aroma (* Acacia farnesiana ) and mesquite aroma (* Prosopis juliflorae ), respectively.

In the gaps of lower and upper montane forests of the Cordillera Highlands, the prolific and gregarious alders * Alnus maritima and * A. nepalensis also tend to form pure stands and these could also potentially be bio-invasive species in these parts of the country.

Tree plantations and natural forest stands should be distant and dispersal of bio-invasive propagules should be avoided. Bio-invasive species that have very long dispersal abilities and with allelopathic properties should be checked and banned in all successional stages of natural forests, for example paper mulberry and mahogany. Dispersal radius of suspect bio-invasive exotic tree species should be studied, so that plantations that are safe from becoming sources of bio-invasive species may be designed.

Agroforestry Research Center - FORI . 1980. Introducing a fast-growing Acacia species. Canopy , 6(8): 1.

Alvarez E.M. 2001. Monitoring the spread of large leaf mahogany (*Swietenia macrophylla King ) in lowland dipterocarp forest in Mt. Makiling, Laguna . Unpublished B.S. Forestry Thesis, UPLB-CFNR.

Anonymous . 1930. Notes and jottings from the Bureau of Forestry Plantations. Makiling Echo , January 23, 1930.

Baguinon N.T. 2000. ENRM 202: Forest and terrestrial ecosystems. Published by U.P. Open University. 409pp.

Bakuzis E.V. 1969. Forestry viewed in an ecosystem perspective. In: The Ecosystem Concept in Natural Resource Management . Ed. by. George M. Van Dyne. pp. 189-254.

Arias S.C. and Binua T.M. 1966. Exotic Gmelina : another fast-grower. Reforestation Monthly 6(1 and 2): 3.

Brown W.H. 1919. Vegetation of Philippine mountains . Manila: Bureau of Printing.

Caguioa V. 1953. Planting exotic species in the Philippines . Soil resources and forestry, Pacific science congress , vol. 5, p. 499-532.

Castillo R.R. 2001. Vegetation analysis of undergrowth plants in lowland forest of Mt. Makiling as a tool in assessing the advance and spread of big leaf mahogany (*Swietenia macrophylla King ). Unpublished B.S. Forestry Thesis, UPLB-CFNR.

DENR-NBSAP . 1997. Philippine biodiversity: An assessment and plan of action . Bookmark, Inc., Makati City, 298 p.

Domingo I.L. 1983. Industrial Pulpwood Plantations. First Asean Forestry Congress , 10-15 October 1983, PICC, Manila, Philippines. P. 18.

Gruezo W.S. 2000. Floral Diversity Profile of Mt. Makiling Forest Reserve, Luzon, Philippines. ASEAN Regional Conference on Biodiversity Conservation , 20-21 September 2000, College of Forestry and Natural Resources, U.P. at Los Baños, College, Laguna, PHILIPPINES. p. 3.

Hilleshog Forestry AB. 1984. The Palawan botanical expedition, final report . IPAS Final Report, June 1, 1992.

Jacobs M. 1975. The world on Luzon’s highest mountains . Lecture in UNESCO-MAB, BIOTROP, Bogor, Indonesia.

Kowal N.E. 1975. Shifting cultivation, fire, and pine forest in the Cordillera Central, Luzon, Philippines . Lecture in UNESCO-MAB, BIOTROP, Bogor, Indonesia.

Lizardo L. 1960. Results of trial planting of Eucalyptus in the Philippines. The Philippine Journal of Forestry. 16(1-2): 31.

Merrill E.D. 1921-26. An enumeration of Philippine flowering plants . Manila: Bureau of Science, vol. 4.

Merrill E.D. 1945. Plant life of the Pacific world . New York: MacMillan Co., 295 pp.

Merrill E.D. and Merritt M.L. 1910. Flora of Mount Pulog. Philippine Journal of Science 5(4-5): 287-403.

Newman M.F., Burgess P.F. and Whitmore T.C. 1996. Manuals of dipterocarps for foresters - Philippines . Published by Royal Botanic Garden, Edinburgh and CIFOR, Jakarta. 124 pp.

Ponce S.S. 1933. Mahogany as a reforestation crop. The Makiling Echo 12 (1): 7.

Rojo J.P. 1999. Revised lexicon of Philippine trees . Forest Products Research and Development Institute, Department of Science and Technology. 484pp.

Tamesis F. and Sulit C. 1937. Reforestation and flood control. The Makiling Echo 16(2): 80-97.

Thinley P. 2002. Negative interaction between large leaf mahogany (*Swietenia macrophylla King ) and some indigenous tree secies in lowland forest of Mt. Makiling - allelopathy, a possible cause? Unpublished B.S. Forestry Thesis, UPLB-CFNR.

Whitford H.N. 1906. The vegetation of the Lamao Forest Reserve. Philippine Journal of Science . 1(4): 373.

Whitford H.N. 1911. The forests of the Philippines . Part I. Forest Types and Products. Manila: Bureau of Printing. 94pp.

Status of forest invasive species in Sri Lanka

N.D.R. Weerawardane and J. Dissanayake
Forest Department
Ministry of Environment and Natural Resources

Sri Lanka has a land area of about 6.5 million hectares. Sri Lanka is a small but biologically diverse country that is recognized as a biodiversity hotspot of global importance for plants. Its varied topography and tropical conditions have given rise to this high level of biodiversity. There are many plant and animal species endemic to the country. Much of the diversity is found in the wet zone located in the southwest parts of the country. Human threats to biodiversity are greatest in this part of the country, due to the dense human population. It has been noted in the past that bio-invasions can have serious negative impacts on the function of these ecosystems. The direct economic consequences are more prominent in the agricultural sector, while the indirect economic consequences will be the loss of biodiversity. The agricultural sector has suffered a lot in the past from intentional or unintentional introductions of alien pests and diseases, including weed species. However, in more recent times attention has been given to the introduction of invasive species and their impacts on biodiversity in the country.

General overview of forest types in the country

According to the forest cover map prepared in 1992, Sri Lanka’s closed natural forest cover was 23.9 percent of the total land area, which amounts to about 1.5 million hectares. Including sparse forests, the total natural forest cover is 30.9 percent of the land cover, which is around two million hectares. The average rate of deforestation during the past few decades, both planned and unplanned, has been around 42 000 hectares per year (Bandaratillake, 2001). The major natural forest ecosystems and their extent are presented in Table 1.


Constant, Pierre. The Galápagos Islands. New York: W.W. Norton & Company, 2001.

Darwin, Charles. The Voyage of the Beagle. New York: Nal Penguin 1988.

Eibl-Eibesfeldt, I. "The Large Iguanas of the Galápagos Islands." In Galápagos—Key Environments. Ed. R. Perry. Elmsford, NY: Pergamon Press, 1984.

Kunstaetter, Roger. Ecuador and Galápagos Handbook. Bath, England: Footprint Handbooks, 2003.

Mackenzie, Aulay, Andy S. Ball, and Sonia R. Virdee. Ecology. New York: Springer-Verlag, 2001.

Simkin, T. "Geology of the Galápagos Islands." In Galápagos—Key Environments. Ed. R. Perry. Elmsford, NY: Pergamon Press, 1984.

Thornton, I. Darwin's Islands: A Natural History of the Galápagos. New York: Natural History Press, 1971.

Journal Articles

Partecke, Jesko, Arndt von Haeseler, and Martin Wikelski. "Territory establishment in lekking marine iguanas, Amblyrhynchus cristatus: support for the hotshot mechanism." Behavioral Ecology and Sociobiology 51 (2002): 579-587.

Wikelski, Martin, C. Carbone, and F. Trillmich. "Lekking in marine iguanas: female grouping and male reproductive strategies." Animal Behaviors 52 (1996): 581-596.

Challenges Facing the Galápagos Islands

The Galápagos Islands have evolved unique species of animals and plants found nowhere else on Earth. In 1835, young Charles Darwin visited the islands, and what he learned here helped inspire his theory of natural selection. In 1978, the Galápagos Islands were designated a UNESCO World Heritage site, signifying their “outstanding value to humanity.” Today, they are a living laboratory of evolution and one of the world’s premier ecotourism destinations. They are, indeed, a priceless world heritage.

But like other isolated island groups, the Galápagos Islands face serious challenges for the long-term survival of their terrestrial and marine ecosystems. The International Galápagos Tour Operators Association (IGTOA) and its members are helping to meet these challenges in significant ways, one of the most important of which is providing ecotours to the Galápagos. Tourism, in fact, funds scientific research and provides revenue that helps give the Ecuadorian government the incentive and resources to protect the islands.

Tourism itself, however, can create other problems, such as invasive, introduced species and burgeoning population growth. Every IGTOA member aids in addressing these issues not only by providing Galápagos tours, but by contributing precious and greatly needed monies for project grants and scholarships that directly benefit the islands.

Read about the archipelago’s challenges below, and learn how IGTOA members are actively involved in working to address them. Then travel to the Islas Encantadas with an IGTOA member, secure in the knowledge that you, too, are part of the solutions.

Introduced Species

From pirates and whalers to modern travelers, humans have, of course, left their “marks” wherever they have traveled in the Galápagos Islands. But one aspect of our kind’s arrival here has been particularly devastating to the fragile ecosystems in the archipelago: introduced, invasive plants and animals.

The most destructive aliens in the Galápagos are goats, which were brought to the islands in the 1850s by whalers looking for an alternative source of meat. Goats are exceptionally well adapted to survive in the Galápagos, whether in the arid lowlands or the moist highlands. Hardy animals, goats can navigate extreme terrain, climb trees, and drink seawater. But they consume valuable foods that Galápagos giant tortoises and iguanas need to live. If left alone, goats can turn a low-lying island into a desert in short time.

The Charles Darwin Research Station started the first systematic eradication program in 1965 in order to rid Santa Fé Island of goats. With no Transition or Moist Zones, the low island was known for its wide, open plains studded with prickly pear cacti forests and palo santo trees. Goats had severely damaged this vegetation. Ten years later, however, the last goat was culled on Santa Fé, and the island’s plant life recovered its lost density. The native rice rat is thriving again, as are land iguanas.

While goat eradication on other islands is making huge strides, there are other alien species currently threatening the delicate Galápagos ecosystems. Black rats, brown rats, cats, cattle, dogs, donkeys, horses, mice, and pigs are some of the worst offenders.

There have been more than seven hundred species of introduced, invasive plants to the Galápagos. The quinine tree, guava, and elephant grass are just a few examples. Unknown numbers of non-native invertebrates have arrived, too, such as the cottony cushion scale and fire ants.

A big step forward in controlling the introduction of new species to the islands came in 1999 when the Galápagos Inspection and Quarantine System (or “SICGAL,” its acronym in Spanish) was created. It was formally established in 2000. A program of the Ecuadorian Service for Agricultural Health, SICGAL works to prevent new species and organisms from being introduced into the Galápagos Islands by monitoring ports of entry and agricultural zones on the inhabited islands, utilizing protocols for fumigating incoming planes and boats, providing training for inspectors and technicians, and publishing and disseminating lists of permitted and prohibited products, among other efforts.

Currently, the Charles Darwin Research Station, the Galápagos National Park Service, and other organizations in the islands — such as the International Galápagos Tour Operators Association (IGTOA) — have set their sights on eliminating all feral cattle, donkeys, goats, and pigs from the archipelago getting rid of introduced rodents from the islands wiping out the freshwater tilapia in El Junco Lake on San Cristóbal and instituting humane sterilization programs for cats and dogs on inhabited islands. Feral cats and dogs, most likely introduced to the islands by early settlers, have especially been a threat to tortoise eggs, native iguana species, bird chicks, and even penguins.

In addition, feasibility studies are being conducted on using biological controls to deal with introduced ants, wasps, and the mosquito that potentially carries the West Nile virus. Methods are being developed to control parasitic flies that endanger their host birds, and attempts to eradicate fire ants from the larger islands and priority small islands are still going on.

But eradicating introduced species and keeping new ones from arriving is a never-ending and enormously costly struggle. To help abate some of these expenditures, IGTOA has provided funds to the Charles Darwin Research Station for a neutering program to prevent the further spread of feral cats and dogs on the islands.

In 2012, WildAid, an organization whose mission is to end illegal wildlife trade by reducing demand through public awareness campaigns and providing comprehensive marine protection, received $25,000 from IGTOA, which supported a preventive quarantine initiative in the Galápagos Islands supply chain. The program is slated to design internationally accepted biosecurity protocols at the embarkation port in Guayaquil. The monies from IGTOA will specifically be used to help in procuring a biosecurity expert and equipment.

Human Impact

We humans are an introduced and invasive species to the Galápagos Islands, and there has been a dramatic growth in our numbers in recent years. Searching for a better life, settlers from mainland Ecuador have moved to the islands in droves, increasing the Galápagos population by more than 300 percent in the past few decades. This spiking population pressure is causing serious problems for conservation.

With only 3 percent of the islands set aside for human settlement, there is little room for this influx of people — and little for them to do except fish. Competition between local fishermen, the Galápagos National Park Service, and conservation workers has been heated and sometimes violent.

Aside from the pressure put on the archipelago’s natural resources (such as fish), this large growth means an increase in generated garbage, which has often been dumped in open-air sites and burned with no sort of treatment or separation. It is essential — if the measures already put in place to protect the biodiversity of the islands are to succeed — that the people who live here are brought into the process that they help provide the answers to the islands’ challenges rather than be part of the problems. This can only be achieved via education and carefully crafted programs to make full and sustainable use of the economic resources found here.

Beginning in the 1960s, the Galápagos Islands saw a rise in a new type of human arrival, the ecotourist. As tourism began to increase, new pressures have been placed upon the islands.

For decades, tourists have marveled at the rich flora and fauna of the Galápagos. In the sixties, there were about 1,000 tourists per year. By 2012, that number had grown to more than 170,000. A second airport was built. Though measures are in place to protect the environment in the Galápagos, park officials have noted measurable changes due to tourism, including decreased flora, expansion of marked trails into protected areas, and increased waste material needing disposal.

Both of these stakeholder groups in the Galápagos — residents and tourists — have made attempts to arrest the escalation of ecological degradation in the Galápagos. One of the strategies that was introduced in the late 1990s was putting a cap or maximum limit on the number of visitors who could be on the main islands at any given time.

The Galápagos has also placed a strong emphasis on the values and practices of ecotourism in an attempt to attract a certain kind of tourist one who is respectful of the ecology of the place and is sensitive to the fact that once lost, it cannot be recovered. Residents and tourists in the Galápagos are inextricably linked: For locals, keeping the Galápagos pristine is not simply a matter of protecting biodiversity but necessary for the economy, which thrives as a result of the tourist industry.

In order to help alleviate the human impact on Galápagos ecosystems, IGTOA has supported several initiatives in the islands, such as the Academy Bay cleanup, which was started by a group of local fishermen. They netted more than eight thousand pounds of waste.

In early 2001, a grounded ship spilled more than two hundred thousand gallons of diesel and bunker fuel into Galápagos waters. IGTOA provided emergency funds to help in the cleanup.

Threats to the Marine Reserve

The Galápagos archipelago has a rich marine ecosystem, nurtured by a confluence of ocean currents. This supports all terrestrial life on the islands. But illegal industrial fishing and over-fishing by locals threaten to undermine this wealth.

When migrants to the islands cannot find work in tourism, they often get jobs in the fishing industry. The sea cucumber and sharks of the Galápagos have become targets, both popular in Asian markets for their aphrodisiac and medicinal qualities. Due to the alarming decrease of sea cucumbers in the early 1990s, an executive decree enforced by the Galápagos National Park Service banned all fishing of them in the islands. Fishermen were not happy. Although a quota has replaced the ban, there have continuous strikes. In April 2004, angry fishermen besieged the Charles Darwin Research Station and demanded the right to use bigger nets and longer lines. The seizure ended with an agreement signed by César Narváez (then Ecuador’s minister of the environment), and the artisanal fishermen.

Today, according to marine biologists, sea cucumbers — along with lobsters — remain at dangerously low levels. And ships from other countries routinely enter the marine reserve illegally in search of rich catches, including sharks, which are harvested solely for their fins.

Overfishing has also significantly weakened the marine ecosystem’s ability to recover from the devastation caused by the El Niño of 1982–83, which triggered abnormal weather conditions. That climate event destroyed coral reefs in the archipelago, many of which had persisted for at least four hundred years. Fishermen had removed so many large predatory fish and lobsters from the islands’ seas, that huge numbers of sea urchins were able to colonize the area. They then overgrazed the coral, damaging it further and preventing it from re-establishing.

It seems that the Galápagos Islands are now teaching us about the far-reaching impacts of climate change on ocean ecosystems. Writes Sylvia Earle of the National Geographic Society, “Nowhere on Earth are the combined impacts of climate change and overfishing more clearly defined than in the Galápagos Islands. Decades of data link recent fishing pressures to disruption of the islands’ fine-tuned systems, making them more vulnerable to natural and anthropogenic changes in climate.”

The Galápagos Marine Reserve was established in 1986 by presidential decree of Leon Febrès Cordero. La Reserva Marina de Galápagos is one of the largest in the world. In 2001, UNESCO expanded the World Heritage Site status of the Galápagos (named in 1978) to include the Galápagos Marine Reserve. IGTOA has participated in a number of projects to help protect this natural jewel, such as:

  • providing anchorage off Wolf Island to support patrols looking for illegal fishing activity and shark finning in this remote sector
  • donating a GPS system and video equipment to be used by Galápagos National Park Service rangers when they patrol the islands for illegal fishing
  • and supporting WildAid in their information campaign to stop illegal shark finning.

Ecotourism has brought great economic benefit to Ecuador, and it remains the only practical way of supporting the Galápagos National Park. The model of low-impact tourism developed in the Galápagos has served the islands well.

Yet there are unwanted by-products from the tourist industry, such as contamination from boat paint and engines, oil spills, overused sites, a drain on the fresh water supply, and the introduction of plants and animals from the mainland. All of these must be addressed for tourism to remain a positive force. Tourism also needs to be kept to sustainable levels. This means a limit to the number of tourists, restriction on the type of tourism development, and close monitoring of tourist impacts.

In February 2012, the Galápagos National Park instituted new regulations to enhance tourists’ experiences while protecting the fragile ecosystems of the islands.

Under previous regulations, most tour providers were limited to seven-night itineraries (with only a few authorized to conduct ten-night or fourteen-night trips). The new regulations required that cruises in the Galápagos operate on a fifteen-day/fourteen-night schedule. Operators may divide that span of time into a maximum of four segments. Most tour operators have split their itineraries into one of several options: 1) two, seven-night trips 2) two, five-night tours and one, four-night trip 3) two, four-night tours and one, six-night trip or 4) two, four-night and two, three-night trips. During its fifteen-day timeframe, a boat may not visit the same site twice, with the exception of the Charles Darwin Research Station on Santa Cruz Island.

Under the previous regulations, some sites — such as Darwin Bay on Genovesa Island and Tagus Cove on Isabela Island — were off-limits to larger vessels. Lifting that ban resulted in increased visitor numbers at underused spots and decreased numbers at sites that are becoming imperiled from too much traffic.

For the first half of 2011, the majority of travelers landed at the airport on Baltra Island. A smaller share of visitors landed at the San Cristóbal Island airport. By including the requirement in the new regulations that the airport on San Cristóbal be utilized at least once in every fifteen-day/fourteen-night cruise schedule, some of the tourist pressure on Baltra was also lightened.

The Galápagos Islands were among the first group of sites added to the World Heritage List in 1978. But in 2007, threats from increasing tourism, overfishing, and encroaching invasive species put the Galápagos on the List of World Heritage in Danger places. However, because of Ecuador’s progress in strengthening conservation measures, the Galápagos were removed from that roster in July 2010.

IGTOA has been instrumental in establishing a best practices program for the travel industry by providing funds to Conservation International and Rainforest Alliance for their program to institute standards of operation for tour companies.

Welfare of Galápagos Residents

Whether through fishing or the tourism industry, it is nature that provides most of the livelihoods in the Galápagos Islands. The fishing community makes up almost 3 percent of the population and is organized into cooperatives that, with the help of the Galápagos National Park Service and other conservation organizations, collaborate to maintain sustainable fishing practices. The park is also a large employer of residents who work as guards on boats that patrol against illegal fishing or do the tough work of helping to eradicate introduced species.

The youthful population, with an average age of thirteen to fourteen years, suffers from limited health care and a poor education system that makes it difficult for even the best students to qualify for universities on the mainland. But the vitality of the Galápagos depends on having enough economic opportunities for residents — opportunities that are also environmentally friendly. Recognizing this, the Charles Darwin Research Station (CDRS) employs and trains many natives. And tourism, while a challenge to the islands’ ecosystems, is the source of most of the jobs in the Galápagos, including certified guides trained by the park service, boat operators, souvenir vendors, and town employees. In fact, one islander is employed for every four tourists who visit.

In 2012, IGTOA awarded the Charles Darwin Research Station with a grant of $28,000. IGTOA members allocated $10,000 of these monies to the station for general operating support — to help it improve its physical and staffing infrastructure in order to meet the islands’ present and future challenges. The remaining $18,000 was awarded towards an interpretive services program.

The CDRS on Santa Cruz Island (and its giant tortoise captive breeding center located on-site) has become an important visitor stop for cruise- and land-based tourists. Guides are the critical link between these visitors — who are potential donors — and the Charles Darwin Foundation (CDF). An interpretive services team of volunteers (international, Ecuadorian, and Galápagos residents) is maintained by the CDRS, and the grant money was put to use to make these volunteers more knowledgeable about and have up-to-date information regarding the foundation’s work.

The executive director of the Charles Darwin Research Station, Swen Lorenz, said at the time, “CDF is very pleased to continue partnering with IGTOA in providing for a visitor services team, which enables young Ecuadorians and Galápagos residents to gain experience in tourism and public relations. Our goal is for visitors to the station to receive personal attention to make their visits as pleasant and informative as possible. We look forward to continuing our collaboration and to working together with IGTOA to protect and conserve the natural biodiversity of the Galápagos archipelago.”

The people of the Galápagos themselves will ultimately be the best stewards of their natural heritage. Those who live in the islands require good housing, health facilities, education, and jobs that contribute to the future of the islands. Sharing in the benefits of tourism will help them achieve those things.

Other projects that IGTOA has participated in to improve the lives of Galápagos residents include:

  • a recycling center — IGTOA supported the Funcacion Galápagos’ Recycling Center on Santa Cruz Island
  • a scholarship for a research project — IGTOA sponsored an Ecuadorian graduate student working on baseline studies of the Galápagos giant tortoise at the Charles Darwin Research Station
  • a scouts program in Puerto Ayora — IGTOA funded a project to provide environmental education and activities for a mixed-gender scout group on Santa Cruz Island.
Welfare and Education of Visitors

Ecotourism is a term that has alternately been described as “green travel,” “sustainable tourism,” or “nature-based travel.” The actual definition of ecotourism as defined by the International Ecotourism Society is: “Responsible travel to natural areas which conserves the environment and improves the welfare of the local people.” There are many benefits to this specialized travel style, including preserving the environment and natural resources of the places you visit and learning about new cultures.

The best way to experience the Galápagos Islands is as a part of a guided tour aboard a small cruising vessel, which functions as your “home” for the duration of your visit. Ships anchor near islands, and passengers are ferried ashore on pangas (small, Zodiac-type boats) twice a day. Each island offers different natural wonders. Knowledgeable naturalists help you to interpret the islands’ wildlife and plants while you are ashore, making the unique biology of each island come alive.

Visitors to the Galápagos must be accompanied at all times by guides who have been trained by the Charles Darwin Research Station (CDRS) and licensed by the Galápagos National Park. This rule protects you, as well as the park. Galápagos guides are intimately familiar with the visitor sites and are enthusiastic to share their knowledge. During evenings aboard ship, the guides give briefings on the day’s and the following day’s events. Recognizing the high level of training that needs to be provided to ship captains, crews, and naturalist guides in order to make your visit as educational as possible, IGTOA has provided funds to purchase hundreds of books for a library in Puerto Ayora, to be used by guides and crews in their studies.

And in order to help visitors learn about the Galápagos Islands and its culture, IGTOA has funded several staff positions at Van Straelen Hall, the visitor interpretation center at the Charles Darwin Research Station on Santa Cruz Island. The CDRS is an international non-profit organization, instrumental in providing the park service with scientific information and advice. Station facilities include a library, museum, herbarium, darkroom, computer center, marine laboratory, plant nursery, a research vessel named Beagle, and a visitor center. More than two hundred scientists, educators, volunteers, and students from Ecuador and around the world conduct conservation-oriented research at the station. In addition, CDRS trains naturalist tour guides and involves the local community in environmental education.

Ecuador’s National Park Service joined forces with CDRS more than forty years ago and together, the two institutions dedicate their services to the use, conservation, and protection of the Galápagos Islands. The station’s activities include a long-running and successful captive breeding program for endangered Galápagos giant tortoises and land iguanas. Three species of land iguanas and eight subspecies of giant tortoises have been saved from extinction. In March 2000, scientists released the one-thousandth tortoise to Española Island which in 1965, had only fourteen of the reptiles remaining. On Pinta Island, the research station and the park service have worked diligently since 1996 to eradicate more than eighty thousand feral goats.

Besides goats and pigs, wild dogs have been removed from Isabela and rats were eradicated on Bartolomé. Other projects strive to conserve endemic and threatened birds, such as the mangrove finch, Galápagos penguin, and flightless cormorant.

Galápagos travelers can do much prior to their departure to prepare themselves for their upcoming journey. In order to get acquainted with this amazing archipelago and its marine reserve, check out the IGTOA recommended reading list. These books will help you gain a deeper understanding of and respect for your host country, its people, and environment.

The IGTOA mission is to preserve and protect the Galápagos Islands as a unique and priceless world heritage. Our members believe that those who travel to the islands deserve good health and safety conditions, boats that are operated responsibly and professionally, and an enriching and educational experience. When you travel with an IGTOA member, you can rest assured that you are traveling with a company that recognizes the challenges facing the Galápagos Islands and that is dedicated to being a part of the solutions. IGTOA members have proven that they care about the conservation of the islands and that they have taken every precaution to give you a memorable, educational, and thrilling adventure, without harming the natural biota of this special environment.

You can see all of IGTOA’s member companies on “Our Members” page. Your experience of a lifetime to the Galápagos Islands is too important to leave to chance. We encourage you to book your Galápagos Islands tour with an IGTOA member.

Governmental Support and Control

The government of Ecuador has been instrumental in protecting the Galápagos Islands, and for this the country should be commended. In recent years, however, there have been lapses in financial support, enforcement of laws and regulations, and proper planning.

In 1959, the Galápagos National Park was created and in 1973, the archipelago was incorporated as the twenty-second province of Ecuador. In 1998, a landmark effort among many organizations and governmental agencies produced the Special Law for the Galápagos, a series of sweeping, protective measures meant to conserve these singular islands and their unique plants and animals. The Special Law addressed three big issues: immigration restriction, quarantine of introduced organisms, and fisheries. Under the law, the marine reserve became a legally protected area — managed by the Galápagos National Park Service, along with local institutions — and the marine reserve area was extended from fifteen to forty nautical miles around the whole archipelago, with only tourism and local artisanal fishing permitted within this area. This outlawed industrial fishing of all types.

The Galápagos National Park comprises 97 percent of the Galápagos archipelago. The remaining 3 percent includes urban areas and agricultural zones inhabited by human populations. To better understand human dynamics on the islands, the Special Law implemented a registration system to monitor existing populations on the islands. In 1998, the Special Law strengthened the mandate of the Galápagos National Institute (INGALA) — a governmental office created in 1980 that is responsible for coordinating regional planning, government funding, and technical assistance in Galápagos — putting it in charge of a more rigorous population registration system that tracks specific population types in and out of the islands.

Currently, there are four human population types defined in the Galápagos: (1) undocumented or “illegal” workers from the mainland of Ecuador (2) “permanent residents,” or the native population of Galápagos (3) “temporary residents,” or workers subject to legal residence restrictions of labor contracts and (4) “tourists.”

Unfortunately, the implementation and enforcement of the Special Law has left much to be desired. IGTOA has supported the government of Ecuador in its efforts to preserve and conserve the Galápagos Islands with an emergency land purchase and a boat certification program. At the request of the Charles Darwin Foundation, IGTOA recently stepped in to provide funds to purchase private land that will be turned into a protected area. And IGTOA gave money to CAPTURGAL (the Galápagos Chamber of Tourism) to help with setting up an international safety certification for locally owned boats operating in the Galápagos.

Challenges Facing the Galápagos Islands Video

For more on the challenges the Galápagos Islands face, watch the video below.

Survival strategies on a semi-arid island: submersion and desiccation tolerances of fiddler crabs from the Galapagos Archipelago

During tidal cycles, fiddler crabs undergo alternating periods of submersion and desiccation. We compare physiological and biochemical adjustments to submersion and desiccation challenge in two gelasminids from the Galapagos archipelago: the indigenous Leptuca helleri, and Minuca galapagensis. We examine population distributions and habitat characteristics survival and hemolymph osmolality after 6 h submersion at several salinities, and after 6 or 12 h desiccation and oxidative stress responses in the hepatopancreas and gills, accompanying glutathione enzyme antioxidant activities, and lipid peroxidation. We provide an integrated biomarker response index based on oxidative stress in each tissue, condition and species. Leptuca helleri occupies a restricted intertidal niche while M. galapagensis is supralittoral. Burrow density in M. galapagensis declined with increasing salinity and decreasing substrate moisture L. helleri burrow density showed no correlation. After 6 h submersion, L. helleri survived only at 21‰S while M. galapagensis survived from 0 to 42 ‰S. After 6 h desiccation, hemolymph osmolality decreased markedly in L. helleri but increased in M. galapagensis. Antioxidant enzyme activities and lipid peroxidation in the hepatopancreas and gills showed tissue- and species-specific responses to submersion and desiccation challenge. The integrated biomarker response indexes for L. helleri were highest in control crabs, driven by oxidative stress. In M. galapagensis, submersion was the determining factor in both tissues. Minuca galapagensis is a generalist species while Leptuca helleri occupies a more restricted intertidal habitat. The species’ respective physiological limitations and flexibilities provide insights into how fiddler crabs might respond to environmental change on semi-arid islands.

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How did hydrophilic plants become established on an isolated island with an arid coastal zone? - Biology

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Biology and Impacts of Pacific Island Invasive Species. 6. Prosopis pallida and Prosopis juliflora (Algarroba, Mesquite, Kiawe) (Fabaceae)

Timothy Gallaher, 1 Mark Merlin 1

1 2 Botany Department, University of Hawai'i at Mānoa, 3190 Maile Way, Room 101, Honolulu, Hawai'i 968

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Prosopis pallida and P. juliflora (commonly referred to as algarroba, mesquite, or kiawe) were introduced from South America to areas in Oceania, Asia, and Africa during the early nineteenth century. In many cases, they naturalized and became widespread. In some places, alien Prosopis species are highly valued for the products and services that they can provide such as shade, cattle fodder, wood for fuel and fence posts, and nectar for honey production. In Australia, four Prosopis species including P. pallida, P. juliflora, P. glandulosa, P. velutina, and their hybrids are considered invasive and are subject to control efforts. After its introduction to Hawai'i in 1828, P. pallida became a dominant tree in arid areas of the main Hawaiian Islands, replacing the native lowland dry forest species that had been decimated by human activity, particularly by the introductions of goats and cattle. Prosopis pallida also has become an important economic species in Hawai'i. Prosopis juliflora, a more recent introduction to Hawai'i, is now spreading and is considered to be a noxious weed. Competition between Prosopis and native species as well as negative impacts of Prosopis on soil and local hydrology have been reported however in some cases Prosopis species are characterized as midsuccessional species that rehabilitate degraded soils, eventually facilitating later-successional woodland. This provides a potential opportunity to use these species in reforestation efforts. Management decisions regarding these species should include a consideration of both their positive and negative ecological roles. If control or eradication is desired, a number of methods have been employed with various degrees of success.

Salt Spray Distribution and Its Impact on Vegetation Zonation on Coastal Dunes: a Review

Salt spray mainly originates from the bursting of bubbles in breaking waves and is often considered as one of the dominant factors contributing to vegetation zonation in coastal dunes. In this paper, the literature on salt spray distribution and impact on dune plants are reviewed. Salt spray distribution is greatly affected by wave energy, wind conditions, distance from the coast, topography, vegetation, precipitation, and sand/soil properties. The amount of salt accumulation and trapping efficiency of the vegetative canopy are largely dependent on the plant characteristics such as architecture and leaf morphology. Salt concentrations in sand mainly vary with soil texture. Salt spray has negative impacts on plant growth and can cause water stress, promote tissue necrosis and leaf loss, reduce stomatal conductance, water use efficiency, photosynthesis, affect assimilates, or hormone supply to the growing organs. Damage to plants is increased by sand and wind abrasion and insect damage on leaves. High humidity, dew formation, light drizzle, and fog increase the rates of salt uptake by plant leaves. Plant seedlings and reproductive organs are more significantly affected by salt spray compared with mature plants and plant leaves respectively. Salt spray can also provide nutrition to plants particularly in coastal dunes with lower soil nutrition and salt accumulation rates. Species near the sea often show phenological, morphological, and physiological adaptations to salt spray including dormant times/seasons, low heights, compacted and asymmetrical canopies, unique leaf morphologies and/or orientations, dense hairs, rigid cuticles, and closed stomata. Surfactants produced from human activities can aggravate the damage on plants at average salt spray levels. Methods to trap salt vary considerably in the literature, and results from different studies may not be comparable due to trap type, placement, and landscape position. Greenhouse versus field experiments and sampling may not always be compatible. The relations between salt spray distribution and vegetation zonation will be further complicated under climate change and human activities.

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Approach and methods

Support for predictions derived from the five hypotheses above was evaluated using molecular phylogenies that include mesic zone biota. We assessed relevant molecular phylogenies that have estimates of dating, and multiple taxa of Australian terrestrial plants and animals. For predictions derived from Hypotheses 1 and 2, phylogenies that dated to, or earlier than, 30 Ma were trait-mapped using parsimony in M esquite ( Maddison & Maddison, 2007 ) as applied by Crisp et al. (2009) to determine whether the most recent common ancestor (MRCA) was reconstructed as inhabiting the mesic zone. The 30 Myr minimum age limit was applied to constrain analyses to lineages that had ancestors present on the Australian landmass at the time of deep ocean separation of Australia from Antarctica, and hence the remainder of Gondwana. To evaluate support for Hypothesis 3, we identified geographical disjunctions between Australian rain forest taxa and their non-Australian closest relatives, and estimated whether the divergence times were < 20 Ma, at which time the Australian and Asian plates began to interact. For the prediction derived from Hypothesis 4, phylogenies that included sister clades of rain forest and sclerophyllous taxa were assessed to determine whether the rain forest clade was species poor compared with its sclerophyll sister. The prediction of Hypothesis 5 was assessed from a survey of phylogeographical literature.


The study provided strong evidence that cladogenesis in P. tentorius can be linked to climatic fluctuations and topographic changes in Southern Africa since the Miocene, thus supporting our hypothesis. It appears if climate was of greater importance than topographic changes in earlier diversification events, but that uplift events together with climate change played a significant role in later divergences. The climatic and topographic changes linked here to early divergences in P. tentorius were also proposed for vicariance in other reptiles at the generic level. Ecologically, each clade in the northern group (Pv-B, Ptr and Pv-A) occurs in a unique niche shaped by different climatic factors. By contrast, clades in the southern group (Ptt-B, Ptt-C, Ptt-D and Ptt-A), showed no significant niche differences.

The results also correspond to other studies showing high taxon diversity (in terms of the number of clades) in the GCFR, not only for plants but also for animals, including reptiles. Diversification patterns of P. tentorius in the late Miocene and Pliocene thus seem to have paralleled those of other organisms, supporting the hypothesis of higher diversity in the GCFR than elsewhere over its distribution range. The strong association of P. tentorius clades with particular regions and vegetation types suggests that the clades evolved allopatrically and that contact in restricted areas is recent, following range expansions of some clades. However, although the clades abut, they do not necessarily overlap because vegetation in the regions regarded as possible intergradation zones forms a mosaic, which may still keep clades distinct.

Nevertheless, more research is necessary to establish if the clades hybridize in the so-called intergradation zones. Conservation awareness is warranted for all clades in the P. tentorius species complex, particularly for Ptt-B, Pv-B, Ptr, Ptt-A and Pv-A. Our study suggests that Ptt-B, Ptt-C, Ptt-A and Ptt-D are a single candidate species but with multiple conservation units, whilst, Ptr, Pv-A and Pv-B are three different species with different conservation units. This study together with the findings in [40] provides strong evidence that P. tentorius requires a taxonomic revision, which would impact the Red List Assessment of the species. As a species, the IUCN currently lists P. tentorius as “Near Threatened” [95] and P. t. trimeni as “Endangered” [95].

Biodiversity (1988)

Restored prairie at the University of Wisconsin Arboretum, Madison. Inset shows members of the Civilian Conservation Corps planting at this site in the late 1930s. Photo courtesy of the Unwersity of Wisconsin Arboretum and Archives.


Reflections on a Half-Century of Experience at the University of Wisconsin-Madison Arboretum


Editor, Restoration & Management Notes, The University of Wisconsin-Madison Arboretum, Madison, Wisconsin

So far, in this volume and in thinking and discussions about the conservation of biological diversity generally, the emphasis has been on preservation of what we already have. This makes sense. Preservation obviously has a critical role to play in the conservation of diversity. At the same time, however, it is clear that by itself preservation is not an adequate strategy for conserving diversity. At best, preservation can only hold on to what already exists. In a world of change, we need more than that. Ultimately, we need a way not only of saving what we have but also of putting the pieces back together when something has been altered, damaged, or even destroyed.

Consider, for example, that

vast areas of both land and water have already been profoundly altered by human activities ranging from agriculture to mining and construction and to various forms of pollution

barring a catastrophe on the scale of nuclear war, human-caused alterations of natural and wilderness areas will continue indefinitely

certain kinds of change&mdashnotably changes in climate&mdashare beyond human control, and they in turn will inevitably change even those areas we have succeeded in preserving

existing wilderness preserves are often inadequate in size or are suboptimal in shape or design in many cases, their value as reservoirs of biodiversity could be dramatically increased by relatively modest increases in size, which could be achieved by active reconstruction of communities around their borders

numerous species are already on the brink of extinction and their habitats have been reduced to a remnant or perhaps eliminated completely, so that their only hope for long-term survival is the re-creation of their habitat by human beings and

the conservation of species ex situ will have little environmental value in the long run unless we find ways of providing habitat for them, often by creating it on disturbed sites.

All these considerations push us, unwillingly it seems at times, beyond a preoccupation with preservation, either in situ or ex situ, as the single strategy for the long-term conservation of diversity and toward a recognition of the importance of an active role for our species in reversing change or repairing damage. Unless, for example, we are prepared simply to write off disturbed lands as potential contributors to diversity, we are going to have to take seriously the problem of increasing diversity on these lands. Similarly, the inevitability of further change, including changes in climate, clearly implies that in order to preserve many communities over the long haul we are going to have to learn not only how to manage them but even how to move them around (Jordan et al., in press). And this brings us to the area of environmental healing, or ecological restoration, which is the subject of this section.


The starting point for this discussion will be the experience of the University of Wisconsin-Madison Arboretum, where research on restoration of ecological communities native to Wisconsin and the upper Midwest has been under way since 1934. Here, under the early leadership of Aldo Leopold and John Curtis, intensive restoration has been carried out on several hundred hectares of land, most of which had been seriously degraded by farming, logging, and sporadic development during the preceding century. Gradually, 40 hectares of tallgrass prairies have been restored on degraded pasture and plowland. A small xeric prairie has been created on an artificially constructed limestone outcropping. Red and white pine forests and boreal forests have been established on old pasture sites, and two types of maple forests are being developed by underplanting existing oak forests in which the understory had been depleted by grazing. The early stages of this effort were carried out by Civilian Conservation Corps crews working out of a camp on the site between 1935 and 1941. More recent work has been carried out by University of Wisconsin-Madison researchers and by the Arboretum staff. In general, the intensity of the restoration effort declined dramatically after 1941, though work continues, and indeed the need for ongoing restoration and management is one of the fundamental lessons that has emerged from the Arboretum&rsquos experiences.

Overall, this has been a pioneering effort, and the Arboretum&rsquos collection of restored and partially restored communities is now the oldest and most extensive of its kind anywhere in the world. Even more to the point, however, because of the Arboretum&rsquos experience, it is possible to make a number of observations about

the nature of restoration, about its potential and its limitations as a strategy for conserving biological diversity, and about the environmental and social conditions under which it is likely to be feasible.


The first lesson that one might derive from this experience is that it is indeed possible, at least under certain circumstances, to re-create reasonably authentic replicas of some native ecological communities (Blewett, 1981). For example, the Arboretum&rsquos two restored tallgrass prairies (Curtis and Greene prairies) now include areas believed to resemble quite closely prairies native to the area&mdashat least with respect to floristic composition. In other words, most of the appropriate vascular plants are present they are present in more or less the right proportions and associations and the number of inappropriate plants&mdashthat is, exotics or plants not native to the tallgrass prairies of this area&mdashis small.

On the other hand, there are large areas on these prairies where ecological or historic authenticity is relatively low and where various exotic species are abundant. Certain of these species have proved to be extremely difficult to remove or control. Some have turned out to be capable of invading the more or less intact prairie community, often at the expense of the native plants. As a result, it is now abundantly clear that the problem of dealing with exotics is an ongoing one and that the struggle will in many instances be unending. Undisturbed natural communities are also vulnerable to invasions by exotic species but, in general, probably less so than communities in the process of being restored. Without doubt, this has turned out to be a major problem facing restorationists.

In addition, the restoration program at the Arboretum has strongly emphasized revegetation, far less attention being paid to the reintroduction of animal species. This is frequently the case in restoration and land reclamation projects, since the assumption is often made that the appropriate animals will find their way into the community once it has developed to a certain point. But this does not always happen for complex reasons that include the size of the communities, their uneven quality, and their isolation from existing animal populations. An instance of this now appears to have occurred in the Arboretum&rsquos restored southern maple forest, where ommission of an ant species that normally aids the dispersal of the seeds of certain herbaceous plants, such as bloodroot (Sanguinaria canadensis) and wild ginger (Asarum canadense), has resulted in the development of these species into peculiar, dense patches (Woods, 1984).

A related problem with restored communities generally is their small size, which can directly influence their ecological quality. Certain animals, for example, may not inhabit restored communities simply because these communities are often too small. This is a major reason why few if any restored prairies include buffalo, for example. At present, the prairie at Fermilab in suburban Chicago is probably the largest restored tallgrass prairie in existence (Nelson, 1987). Of course, this nearly 240-hectare prairie is still very small in comparison to the millions of hectares of prairie that existed in this area at the time of European settlement, and its ability to support populations of large native animals is at best problematic.

In addition to the more conspicuous defects in the composition of restored communities, there are numerous features, such as soil structure and chemistry, composition of soil flora, populations of less conspicuous animals (including insects), and various aspects of ecosystem function, that in many instances may not be authentic. Only rarely have these been studied in any detail.

On the positive side, however, the Arboretum&rsquos restored communities have brought back into the landscape numerous plants and animals that had become rare or had even been eliminated locally. The entire project certainly represents an enormous contribution to what might be called the native diversity of the Madison area. The Arboretum&rsquos restored tallgrass prairies, for example, are now among the largest prairies in Wisconsin, a state that had some 4.8 million hectares of prairie and savanna at the time of European settlement (Curtis, 1959). These prairies alone include more than 300 species of native plants. Some of them, including plants such as big bluestem grass (Andropogon gerardi), compass plant (Silphium laciniatum), and yellow coneflower (Ratibida pinnata), were extremely abundant in presettlement times, often dominating whole landscapes, but were virtually eliminated from the area by the time the restoration efforts at the Arboretum began. These now flourish in the restored communities, which also provide habitat for numerous rare species. Examples from the Arboretum&rsquos collection include such rarities as the white-fringed orchid (Habenaria leucophaea), prairie parsley (Polytaenia nuttallii), smooth phlox (Phlox glaberrima), and wild quinine (Parthenium integrifolium)&mdashall considered threatened or endangered, at least for the state. In general, the Arboretum itself probably has more biological diversity than any other area of comparable size in the state. This is due largely to the presence of the various restored communities.

In short, the Arboretum&rsquos experience shows that restoration of some native communities may be technically feasible under certain conditions. The ecological quality of the resulting communities may vary, but under proper conditions, it may actually be quite high, and restored communities may often resemble the historic community chosen as a model quite closely, at least in floristic composition.


At the same time, the experience of the Arboretum raises a number of questions about the cost of such projects and the social, political, and economic feasibility of carrying them out. Thus, in considering the environmental significance of the Arboretum&rsquos restoration efforts, one should keep in mind that these efforts have been carried out under conditions that clearly limit their relevance to other situations. These conditions include first of all the fact that the Arboretum itself is part of a major university and that its work has been performed primarily for scientific and academic reasons. In other words, from the very beginning, this effort has benefited from its academic setting and has been justified as an experiment or as a way of creating communities for research, rather than as a way of coping with environmental, much less economic, problems.

The second set of conditions that have contributed to the success of the Arboretum project were those directly related to the economic and ecological con-

ditions of the 1930s, notably the Great Depression and the Dustbowl. Together, these national calamities provided conditions (specifically, cheap land, free labor in the form of the Civilian Conservation Corps, and an incentive for ecological restoration) that proved crucial to the development of the Arboretum, but that have also reduced its value as a model for carrying out restoration projects in the real world outside academia. This point carries us outside the little world of the Arboretum to the larger world, where we have to ask a crucial question: What good is restoration? Is it likely to prove merely an academic pursuit or a pastime for environmentalists who happen to be interested in an unusual form of gardening? To just what extent and under what conditions can restoration be expected to contribute in a significant way to the conservation of diversity?

These questions have not yet been dealt with systematically, as far as I am aware. But it is important that we begin to take them seriously. In general, given the interrelatedness of everything on Earth and the inevitability of change, it would seem that an ineluctable logic argues for the importance of restoration as part of any comprehensive strategy for the conservation of biological diversity. Critical as it may be as part of such a strategy, preservation has serious defects. Basically, it is a one-way strategy that offers no way of responding to change or recouping losses. By itself, any such approach is clearly inadequate because in a changing world the quality of the environment is ultimately going to depend not simply upon the amount of land we manage to set aside and to preserve but upon the equilibrium we are able to maintain between the forces of destruction&mdashor change&mdashon the one hand and the forces of recovery on the other. All things considered, and despite its various limitations, it seems likely that restoration will ultimately play an important role in determining the position of this equilibrium.

This being the case, the questions raised above and a whole host of corollary questions and issues take on a great deal of urgency. Can we restore ecological systems? And if so, how authentic will the results be? Which communities lend themselves to restoration, and which are likely to prove more difficult&mdashor even impossible&mdashto restore? To what extent can we hope to re-create communities specifically designed to provide habitat for rare and endangered species? What needs to be known in order to restore a system effectively&mdashand efficiently? What is the state of the art for the restoration of various communities, and what currently limits the effectiveness of restoration techniques for these systems? What sorts of research need to be undertaken in order to refine these techniques?

Beyond these questions about the technical feasibility of restoration, there are the various social, economic, and political questions: How much will it cost? Who will be expected to pay for it, and why? How will the costs compare with those of preservation or with the natural recovery of disturbed systems? What incentive will society have for restoring naturally diverse communities rather than for simply reclaiming land for some other purpose such as agriculture? In general, what incentives can be found for restoring communities&mdashincentives that will ensure that restoration is actually accomplished and that its potential for contributing to biological diversity is effectively exploited?

In fact, there are a number of such incentives, including some traditional ones such as the creation of habitat for fish and game and the use of prairies as pasture

and rangeland. There are also important aesthetic incentives in park and wilderness management and in landscape architecture.

But restored communities may well have other economic values that have not yet been fully identified or widely recognized. Examples include development of wetlands to control water distribution and quality (Holtz, 1986), of prairies to rehabilitate soils degraded by agriculture (Miller and Jastrow, 1986), and of forests as part of a program of sustained-yield timber production (Ashby, 1987). Applications such as these at least suggest ways in which restoration might eventually prove critical as a way of reintegrating native communities into the economies of developed nations, in the process returning them to the landscape on a large scale.

These questions are addressed in the four chapters that follow. The first two are devoted mainly to defining the state of the art of ecological restoration for two community types. In the first of these, Chapter 36, Joy Zedler discusses restoration of a temperate zone community, the tidal wetland. In Chapter 37, Chris Uhl addresses the much-neglected subject of tropical forest restoration. The following two chapters turn to the more socially oriented aspects of the business of restoration. In Chapter 38, John Cairns looks at disturbed lands as opportunities for increasing local and regional biodiversity through restoration. In Chapter 39, John Todd presents some ideas about creating a social, political, and economic context for restoration projects.


Ashby, C. 1987. Forests. Pp. 89&ndash108 in M.E.Gilpin, W.R.Jordan III, and J.D.Aber, eds. Restoration Ecology: A Synthetic Approach to Ecological Research. Cambridge University Press, New York.

Blewett, T.J. 1981. An Ordination Study of Plant Species Ecology in the Arboretum Prairies. Ph.D. Thesis, University of Wisconsin-Madison. 354 pp.

Curtis, J.T. 1959. The Vegetation of Wisconsin. University of Wisconsin-Madison Press. 657 pp.

Holtz, S. 1986. Bringing back a beautiful landscape&mdashwetland restoration on the Des Plaines River, Illinois. Restoration & Management Notes 4:56&ndash61.

Jordan, W.R. III, R.L.Peters, and E.B.Allen. In press. Ecological restoration as a strategy for conserving biological diversity. Environ. Manage.

Miller, R.M., and J.D.Jastrow. 1986. Soil studies at Fermilab support agricultural role for restored prairies. Restoration & Management Notes 4:62&ndash63.

Nelson, H.L. 1987. Prairie restoration in the Chicago area. Restoration & Management Notes 5(2).

Woods, B. 1984. Ants disperse seed of herb species in a restored maple forest. Restoration & Management Notes 2:18.


Can We Do It?


Professor of Biology, San Diego State University, San Diego, California

Along the U.S. coastline, development has reduced the area of coastal wetlands and endangered certain wetland-dependent species. Despite the threats to biodiversity, development of wetland habitat is still permitted by regulatory agencies if project damages can be mitigated by improving degraded wetlands or creating new wetlands from uplands. For example, the California Coastal Act allows one-fourth of a degraded wetland to be destroyed if the remaining three-fourths is enhanced. The expectation is that increased habitat quality will compensate for decreased quantity.

The concept sounds reasonable, but biodiversity is continuing to decline. Why? First, the process allows a loss of habitat acreage. Second, there is no assurance that wetland ecosystems can be manipulated to fulfill restoration promises. The magnitude of the problem is well illustrated by examples from southern California, where more than 75% of the coastal wetland acreage has already been destroyed, where wetland-dependent species have become endangered with extinction, and where coastal development pressures rank highest in the nation. This chapter reviews several restoration plans and implementation projects and suggests measures needed to reverse the trend of declining diversity.


Several large development projects in southern California wetlands have recently been approved by the California Coastal Commission (see Figure 36&ndash1). Three federally endangered species are affected by such projects: the California least tern (Sterna albifrons browni), light-footed clapper rail (Rallus longirostris levipes), and salt marsh bird&rsquos beak (Cordylanthus maritimus spp. maritimus see Figure 36&ndash2).

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