The distribution is presented in 1 km-grids, based on vegetation relevés and digitized data from herbarium specimen, photos, literature and field surveys. Releves date back to 1880.
De Freitas, J.A.
Vegetation maps are a primary and essential tool in biodiversity science, conservation, management, and monitoring as well as in land-use management planning. In this study a semi-detailed landscape-based vegetation map (scale: 1: 46,000) is presented for the 34 km2 Dutch half of Lesser Antillean island of St. Martin (St. Maarten). A vegetation map is especially critical in biodiversity context as St. Maarten lies in a key biodiversity hot spot and is habitat to more than 100 regional endemic animal and plant species of which 12 are island endemic species found only on St. Maarten. The map is based on a total of 56 vegetation plots that were sampled in 1999 using a stratified random sampling design and analysed using TWINSPAN cluster analysis. Two hundred and twenty (220) plant species, representing 40 % of the total known flora (544 species), were recorded in the sample plots.
A total of four main and eleven different sub-landscape types were distinguished based on geology, geomorphology and the eleven distinguished vegetation types. The most dominant landscape type was the hilly landscape type for which seven sub-landscapes were distinguished. The 11 vegetation units we describe represent an important decline from the 16 vegetation types distinguished by STOFFERS (1956). Large changes have clearly occurred in the coverage and composition of the vegetation types of the island. Between the early 1950s and 1999 the total coverage of vegetated areas in St. Maarten declined from 67% to 42% representing a loss of 25% of the total vegetated surface of St. Maarten. Five of the vegetation units of STOFFERS (1956) have disappeared beyond recognition. These are: Hippomane woodland, Vegetation of the salt flats, Strand scrub community, Littoral woodland and Vegetation of the rock pavement. While Hippomane woodland has in part likely been lost due to hurricane impacts, most vegetation loss and degradation has been due to massive urbanization and touristic development especially in the lower and coastal parts of the island. As a consequence the vegetation types of the higher and steeper sections of the island have remained among the least disturbed and degraded. Some vegetation units described by STOFFERS (1956) have also disappeared due to actual vegetation regeneration and succession to a more diverse state due to the decline in agriculture and livestock grazing. Goat grazing remains especially high in two of the eleven vegetation types we described (50 – 80 % presence of dung in the study plots). The highest goat presence was recorded in a “new” vegetation unit (type 6) that has developed based on the domination of the invasive plants Leucaena leucocephala (jumbie bean, lead tree) and Antigonon leptopus (coral vine).
The main threats to the vegetation of St. Maarten we discern based on this mapping project are 1) the massive scale of urbanization and touristic development the island has undergone, 2) continued uncontrolled livestock grazing, 3) invasive plant species, and 4) hurricane impacts. Unless actions are taken to stem the loss of and help restore natural vegetations, we predict that the island will continue to lose its plant diversity, and along with it the fauna which depends on that vegetation. Continued loss of natural vegetation will further exacerbate erosion, loss of freshwater, soil quality and 5 environmental resilience to climate change, as well as sedimentation in the marine environment and the concomitant loss of shallow marine habitats like seagrass beds and coral reefs.
To help prevent this scenario from developing further, we recommend several practical measures: 1) implement land-use planning and designate protected areas to preserve the native flora and fauna, 2) limit and control roaming livestock, 3) legally protect endangered and ecologically critical plant species, 4) connect protected areas by means of ecological corridors, 5) implement measures to control and limit invasive species and 6) implement long-term vegetation monitoring
The Jan Thiel lagoon can be considered the most important wetland of Curaçao based on its combined value as a feeding habitat for terns. As is likely the case in general with the other saliñas of Curaçao, Jan Thiel lagoon appears to be of the greatest significance to flamingos during the dry season when the larger wetlands in Venezuela run dry. The lagoon is also an area that has historically provided conditions suitable for massive nesting by rare species of terns. Nesting by terns still occurs but on a much lesser scale and with fewer species. During the rainy season, and because of the presence of many dams which retain fresh water on the eastern half of the lagoon, the area is of persistent value to several waterbirds which showed a preference for feeding in less saline water. These include species such as ducks, sandpipers, and black-winged stilts.
The lagoon is approximately 80 ha and is surrounded by approximately 228 ha of additional scenic conservation area which contain rare tracts of native vegetation and which provide valuable habitat to many other native species such as konènchi, sloke, tapa kaminda, and warawara. The best vegetations are found on the eastern side of the lagoon, particularly the southern quadrant of the eastern half of the lagoon. This quadrant has quite rare vegetation, best described as a Haematoxylon-Coccoloba vegetation in which the dreifi shimaron is found to be abundant on volcanic soil. Such vegetation is also known from areas of Oostpunt, Malpais, and Seru Cocori. Other species remarkably abundant in the Haematoxylon-Coccoloba unit include the mata piska and the palu di pushi while the presence of scattered kibrahacha and mangel di sabana likely indicate species which were once much more abundant but which have somehow survived the intensive use of this area in the past. Rare plant species found in the area include the trees lumbra blanku (Croton niveus), kurahout (Peltophorum acutifolum), mata kombles (Schoepfia schreberi), "fuma machu" (Vitex cymosa). For the latter species, less than 20 trees are known to exist in the Dutch Antilles.
A major limitation to the avifaunal use of the lagoon, particularly the flamingos and tern nesting is the current high level of uncontrolled recreational disturbance. Unintentional recreational disturbance can likely be greatly reduced by a combination of properly informing visitors, by planting vegetation barriers to shelter visitors from the constant sight of the birds and by partially redirecting trails.
The planned Jan Thiel-Amandelweg road is a major threat to the ecological integrity of the conservation area. The road is protected to lie directly in the two most important freshwater areas bordering the lagoon and on top of one of the four locations which support tern breeding. The mere physical presence of the road is in itself a scourge to the vegetation as is cuts through a part of the Haematoxylon-Coccoloba vegetation and lies directly on top of three (fortunately resprouting) very rare Vitex cymosa trees. If this road is ever built it will add a large source of constant disturbance (incl. traffic noise) for much of the eastern half of the lagoon (which is the principal area used by the avifauna), and a major source of littering and contaminants from vehicles.
The abandoned landfill of Koraal Specht has not been sealed to prevent rainwater percolation and several seeps were seen to emanate from the landfill and flow into the lagoon. The landfill likely forms a serious long-term threat to the lagoon and a study is needed with regards to the potential leaching of contaminants.
This report describes a field visit to the Caribbean island of Bonaire aiming at collection of field data on the arid vegetation, which consists largely of dry thorn scrub, cactus scrub and dry tropical forest. Vegetation releves have been amde at 23 sites, among which eight sites that have been surveyed in 1999. Besides 50 short field descriptions have been made as a basis for a land-use map. The report describes how the more than 1000 releves of the Dutch Caribbean islands, which are stored in the vegetation database CACTUS, may be analysed to provide insight in natural processes like vegetation succession and effects of land use, climate change and other factors. Besides, the report contains an advice for the representative Ministry of Agriculture, Nature and Food Quality on the island about the (better) conservation of sites on the limestone terraces with very well developed woodland.
The lands of the former Bolivia Plantation amount to about three-thousand three-hundred (3,300) hectares of wildlands and basically constitute the eastern quadrant of the island of Bonaire, stretching along the central east coast from Lagun to Boka Olivia. A brief biological inventory of Bolivia was conducted 3-6 November 1997, in which semiquantitative data was collected on the terrestrial flora and fauna at 34 different sites and/or transects. With exception of most of the lower limestone terrace, Bolivia was found to be well vegetated in terms of overall vegetation cover, and to possess much in the way of of scenic landscapes.
Whereas Stoffers (1956) indicated most of the Middle (limestone) Terrace areas as constituting dry evergreen vegetation, at present most dry evergreen species are virtually absent. One consequence of this finding is that the (likely) better developed dry evergreen formations on Bonaire (e.g. Colombia, Karpata, Tolo) must now be accorded a much higher conservation priority than could heretofore be realised.
Bolivia shows extensive signs of past agricultural use and strip-mining for coral rubble. At present feral livestock (goats and donkeys) are at clearly detrimental densities, and mining activities form an immediate threat to some very rare coastal rubble vegetation.
Based on this initial assessment, several principal conservation priorities for Bolivia can be identified. These are:
- Nesting habitat for the Bonaire Lora, along the coastal terrace edge
- Ecologically important food sources, especially candelabra cacti concentrated in various areas
- The cave systems of Roshikiri and Spelonk
- Terrace edge area along the length of the coastline
- Coastal rubble vegetation between Spelonk and Boven Bolivia
- Brasía terrace woodland of Beneden Bolivia
- Washikemba woodland in the souther parts of Bolivia.
On the basis of these principal conservation values and the area's greater role as ecological corridor beween the northern and souther halves of the island, an initial scetch of recommended conservation areas is presented. The results indicate that any potential development should be concentrated in the central section of Bolivia.
Sabal antillensis is endemic to the Dutch Caribbean islands of Curagao and Bonaire. Both island populations were thoroughly assessed in 1979, and subsequent management of both sites differed over the last forty years. Resurvey of these palms in 2018 clearly shows the value of exotic herbivore management for palm conservation: exclusion and management of introduced herbivores coincides with a vast increase in palms on Curagao. We recommend a similar program for the much smaller and much more vulnerable population on Bonaire, as well as continued propagation of seeds for outplanting.
Keywords: endemic species, Caribbean, Saba, Saint Eustatius, Saint Marten, Saba Bank
Endemic species and subspecies (or “taxa” for short) having restricted geographic distributions are an extremely important feature of biodiversity and a key criterion to conservation valuation and nature management goal-setting. Saba, St. Eustatius and St. Martin (the Dutch SSS islands) form part of the Caribbean biodiversity hotspot region but up to now no systematic assessment was available on the occurrence of endemic animals and plants on these islands and in the surrounding marine areas (incl. Saba Bank). We here provide such a preliminary assessment as an aid to conservation and nature management, and to help in prioritizing future research. Our assessment shows that the SSS islands and Saba Bank together possess 223 endemic animals and plants (32 subspecies, 191 species), of which 35 are endemic to the SSS islands or Saba Bank, 15 are endemic to the Northern Lesser Antilles (Virgin Islands southwards up to and including Montserrat, including St Kitts Bank and Anguilla Bank endemics), 110 to the Lesser Antilles (Virgin Islands southwards up to and including Grenada) and 58 to the joint Antilles (Lesser and Greater Antilles). Of the 35 island endemics, 8 are marine, 26 are terrestrial and 1 is from brackish water.
The breakdown of the 223 endemic species and subspecies according to larger taxonomic groupings is as follows: Worms (Polychaeta): 1; Spiders, scorpions and pseudoscorpions (Arachnida): 23; Copepods (Hexanauplia): 2; Beetles (Coleoptera): 33; Flies (Diptera): 4; True bugs (Hemiptera):3 ; Sawflies, wasps, bees, and ants (Hymenoptera): 3; Butterflies and moths (Lipidoptera): 12; Dragonflies and damselflies (Odonata): 1; Grasshoppers, locusts and crickets (Orthoptera): 22; Amphipods: 1; Crabs, lobsters and shrimps (Decapoda): 1; Isopoda: 1; Pycnogonida: 1; Bony fish (Actinopterygii): 4; Sharks and rays (Chondrichthyes): 1; Birds: 23; Amphibians: 1; Mammals (bats): 5; Reptiles: 16; Cnidarians: 5; Bivalves: 5; Gastropods: 28; Flatworms (Platyhelminthes) 1; Red Algae: 3; Spermatophyta (Vascular plants): 22.
The breakdown of the 35 taxa that are endemic to the SSS islands or Saba Bank is as follows: Polychaeta: 1; Arachnida: 4; Hexanauplia: 2; Coleoptera: 3; Diptera: 1; Hemiptera: 1; Orthoptera: 10; Bony fish: 2; Reptiles: 3; Bivalves: 1; Gastropods: 3; Red Algae 1; Vascular plants: 3.
The breakdown in numbers of island endemics for the SSS islands and Saba Bank is:
· St. Martin: 12 island endemics (10 animal species and 2 plant species)
· St. Eustatius: 10 island endemics: (8 animals species and 2 plant species)
· Saba: 10 island endemics: (10 animals species, 0 plant species).
· Saba Bank: 3 endemics (3 animal species, 0 plant species)
The number of endemics is probably larger than reported here. Very little marine taxonomic research has been conducted in the SSS islands and many species probably remain to be described. In the past decade many new and potentially endemic species (of algae, fish, corals, sponges, etc.) have been discovered, mainly on the Saba Bank. Furthermore, additional research on specific species groups (e.g. beetles) could result in the discovery of yet more new endemic species. The IUCN assesses the conservation status of plant and animal species worldwide. Most rare and endangered island endemics are not included in the assessments due to lack of information or perceived priority. Therefore, most IUCN-listed threatened species for the SSS islands are species with much wider distributions. Assessments are only available for 42 of the endemic (sub)species of the SSS islands. The only recent endemic ground-dwelling mammal, the Nevis rice rat, is extinct. The endemic bats and bird subspecies have wider dispersal capabilities and currently carry no IUCN threatened listing, eventhough several only survive in tiny, scattered and vulnerable populations. Only
the following six endemic terrestrial reptiles currently carry a IUCN threatened status:
· Critically Endangered: Lesser Antillean Iguana (Iguana delicatissima).
· Endangered: Anguilla Bank Racer (Alsophis rijgersmaei); Spondylurus powelli.
· Vulnerable: Saba Racer (Alsophis rufiventris) and Anguilla Bank Bush Anole (Anolis pogus).
· Near threatened: St. Christopher Ameiva (Pholidoscelis erythrocephalus).
Many of the 223 endemic taxa listed here are restricted to very small populations on one or only a few small islands. This makes them very vulnerable to extinction. Indeed, in the recent past, some species may already have become extinct (e.g. two endemic plants known only from St. Martin). Therefore, assessments of the conservation status of each of the identified endemic taxa are urgently needed for the SSS islands and Saba Bank. In addition, conservation strategies need to be developed to minimize extinction risk for the most endangered endemics.
Five of the largest remaining patches of livestock-inaccessible rock vegetation of Curacao, Netherlands Antilles, were described and compared to rock vegetation which has experienced centuries of livestock grazing. Study rocks (maximum diameters: 20-47 m) were located at two sites differing in rock type and altitude. At the St. Christoffelberg site, study rocks were siliceous and at altitudes of 240-310 m while at the Tafelberg site the rocks were of limestone and at altitudes of 35-150 m. The main vascular species on livestock-inaccessible rocks at both sites was Tillandsia flexuosa. a bromeliad. At the St. Christoffelberg, Tillandsia was principally accompanied by the grass Paspalum secans, the orchid Brassavola nodosa and the herb Portulaca venezuelensis, while at the Tafelberg it was principally accompanied by the vine Serjania curassavica. On livestock-accessible rocks Tillandsia ground cover was reduced to insignificant levels and mature plants were virtually eliminated from the population. Grazed vegetations also showed reduced vascular cover and were principally dominated by the annual grass Aristida adscencionis (St. Christoffelberg site only), the prickly pear Opuntia wentiana and the shrubby tree Acacia tortuosa. None of these weedy species, all of which are widely distributed on the island, were of any significance in ungrazed rock vegetations. It is hypothesized that Tillandsia-dominated ground cover may have been a common feature of the rock vegetation of the island prior to the introduction of livestock.