Ecosystems

An ecosystem is the functional unit and suite formed by all species which inhabit a place (community), the non-living elements which surround these species (biotope), and the relations established between all of these components, creating an interdependency between organisms and their habitat.

Ecosystems are important because they are the natural refuges of species, and harbor great value for conservation and biodiversity. However, since for humans the greatest significance of ecosystems resides in the benefits which can be derived from them, it is important to better know and conserve them. For example, the quantity and quality of the water which we use in our homes depends on ecological and biophysical processes which occur our in the ecosystems which harbor our watersheds.

Ecosystems of the Dominican Republic

Texts extracted and adapted from official information provided by the Ministry of Environment and Natural Resources of the Dominican Republic and the Atlas of Biodiversity of the Dominican Republic, Santillana

Marine Ecosystems

Mangrove:

These are a group of haliophile plants which possess adaptations to tolerate salinity in the substratum and in water. Because of this, their presence is only noted in marine and coastal areas.

In the Dominican Republic there are around 258 km2 of red mangroves (Rizophorae mangle), black mangroves (Avicennia germinans), white mangroves (Laguncularia racemose) and button mangroves (Conocarpus erectus).

Within the Dominican Republic the mangrove is economically important as it represents a source of food for the majority of estuarine and marine organisms living in their vicinity. These ecosystems are characterized by their high productive capacity and production of organic material. They not only form a natural barrier against coastal erosion, upstream salinity, and waves, but also help to improve water quality and act as a potent carbon sink in the fight against climate change.

It is estimated that two-thirds of worldwide fish species depend on the mangrove in one or more of its life-cycles. Mangroves are also nesting and feeding areas for many species of birds and reptiles, and their roots are the perfect substrate for all sorts of commercial uses.

Seagrasses:

Prairies of seagrasses are ecosystems which exist in shallow waters and serve as a habitat for both ecologically important species (such as the West Indian manatee and tortoise) and economically important species (such as the conch and lobster). Their existence is decisive for water quality in coastal zones and they protect marine sediment against erosion. The main species which form marine prairies in the bays and inlets of the Dominican Republic are: Thalassia testudinum, Syringodium filiforme, Halodule wrigthii, and Halophila decipiens.

Coral Reefs:

These are one of the most productive ecosystems, and harbor a great variety of fish, crustaceans and mollusks. They are highly complex communities which host great biological diversity. It is estimated that the island of Hispaniola hosts approximately 57 different species of coral in reefs which make up 5.3% (1,060 km2) of the total area of coral reefs in the Caribbean.

The most common species of coral are: Acropora palmata, Diploria clivosa, Porites porites, Porites asteroides, Millepora complanata, Gorgonias ventalina, Plexaura homomalla.

The Dominican Republic contains various types of coral formations, including ocean banks (Banco de la Plata and Banco de la Navidad), barrier reefs, fringing reefs, and atoll reefs.

Beaches:

These are coastal ecosystems in which unconsolidated sediments such as sand, stones, and pebbles of different make-up and composition accumulate and are cycled around by the wind, currents, and surf. The coastline of a beach is the highest level that waves can reach, and is marked by some combination of an abrupt change in ground slope, dunes or sandbars, and the beginning of coastal vegetation. The shoreline of a beach begins where waves can no longer exert their influence.

Beaches are dynamic ecosystems which give way to natural periods of gain and loss of sediments through coastal dynamics of marine currents and tidal movements. Each beach represents an equilibrium in the free movement of unconsolidated materials, and should remain free of human intervention so that its unique profile may be preserved.

Beaches are a very valuable natural resource for the development of tourism; they are shock-absorbing zones which protect the land from the constant battering of waves and make up a unique habitat for the spawning of endangered species, such as sea turtles. These ecosystems are under threats stemming from extraction of sands, misuse and mismanagement, fragmentation, contamination, and the destruction of original terrestrial vegetation and subsequent introduction of exotic species. Over 200 beaches (link in Spanish) with a total length of 408.1 kilometers have been inventoried in the Dominican Republic.

For the Dominican Republic, beaches are a very valuable natural resource because they serve as the setting for development of recreational activities which support the principal economic activity of the country: tourism.

Rocky Coasts:

Steep rocky shores comprise coastal zones with solid substrate and high erosion. In being exposed to the constant action of waves, winds, the tide, and the sun, these assure a fresh environment with abundant light and ample distribution of nutrients.

The majority of rocky costs in the Dominican Republic are coastal terraces. They occupy 46.18% (770.4 kilometers) of Dominican coastline and are distributed in 41 zones. These can be considered a tourist attraction owing to their geomorphic characteristics. The principal threat to rocky coasts is contamination from urban and industrial waste.

(Map of coastal marine ecosystems. Source: Atlas of Biodiversity and Natural Resources, Ministry of Environment and Natural Resources)

Terrestrial Ecosystems

Halophytic Vegetation:

Halophytic vegetation is defined by the salinity of its soils and the effects of winds. It is characterized by short, salt-tolerant trees, molded by constant winds. Typical halophytic vegetal species are the seagrape (Coccoloba uvifera) and the four species of mangrove: the red mangrove (Rizophorae mangle), black

mangrove (Avicennia germinans), white mangrove (Laguncularia racemose) and button mangrove (Conocarpus erectus). Among halophytic vegetation one can observe fauna such as amphibians, reptiles, and birds such as the flamingo (Phoeniopterus ruber) and the American yellow warbler (Dendroica petechia), in addition to many others.

Tropical Dry Forests:

Scarcity of water, water retention capacity of soils, and high temperatures determine the types of vegetation found in tropical dry forests. Many species of cactus such as the guasábara (Cylindropuntia caribaea), the alpargata (Consolea moniliformis) as well as trees such as the bayahonda (Prosopis juliflora), the guaiacwood (guaiacum offcinalis), the candelón (Acacia scleroxyla) and the cambrón (Acacia macracantha) are found in these zones. The vegetation in tropical dry forests generally possesses broad leaves with spines which assist with water retention. Among the commonly-observed birds in these areas are the flat-billed vireo (Vireo nanus), the yellow-billed cuckoo (Coccyzus americanus) and the black-crowned tanager (Phaenicophilus palmarum). As for land animals, one can find toads, lizards, and the Hispaniolan ground iguana (Cyclura ricordii).

Semi-Deciduous Forests:

Very prolonged periods of drought characterize the vegetation of semi-deciduous forests; that is to say that they will lose their leaves when it is necessary to prevent themselves from drying out. Vegetation in these zones is characterized by forests of medium height which grow on calcareous rock originating from coral as well as forests with very large trees in swamp-like zones and accumulation of organic material. Some examples of this type of ecosystem are found in grasslands, rocky coastal regions, and marshlands.

The most typical trees in semi-deciduous forests are the: copperwood (Bursera simaruba), gregorywood (Bucida buceras), Hispaniola palmetto (Sabal domingensis), West Indian mahogany (Swietenia mahgoni), kapok tree (Ceiba pentandra), and the Haitian catalpa (Catalpa longissimi). Some examples of epiphytes found in these areas are bromelias and orchids. Observable fauna includes frogs, lizards, and snakes such as Cope’s Antilles snake (Antillophis parvifrons), the Hispaniolan boa (Epicrates striatus), and the pointed snake (Uromacer oxyrhynchus). Some birds which make semi-deciduous forests their home are the broad-billed tody (Todus subulatus), the vervain hummingbird (Mellisuga minima), and the common ground dove (Columbina passerine).

Evergreen Broadleaf Forests:

This type of forest is divided into two groups: rainforests and cloud forests. In rainforests, trees of up to 35 meters dominate much of the landscape. They occur in humid tropical conditions characterized by high levels of rainfall. Cloud forests on the other hand are found in mountainous areas and are defined by their highly persistent cloud cover, which leads to high humidity and low temperatures. In both of these types of forests there exists a great abundance of ferns, orchids, and bromelias.

Insofar as plants, evergreen broadleaf forests have the richest diversity of flora in all of the island. Among the most representative trees of these forests are the copey (Clusia rosea), the palo de cruz (Podocarpus hispanoliensis), the chicharrón (Sloanea ilicifolia), the Manacla palm (Prestoea montana), the green ebony tree (Magnolia pallescens), and the Caimoní or Baoruco ebony (Magnolia hamorii). As for some of the types of fauna found in these forests, one can note the Hispaniolan amazon (Amazona ventralis), Hispaniolan parakeet (Aratinga chloroptera) and the Antillean piculet (Nesoctites micromegas).

Pine Forests:

As their name suggests, this type of forest is marked by a predominance of pines, especially the endemic species Pinus occidentalis. They are mainly found in high altitude regions of the Cordillera Central and in the ranges of Baoruco, however they also can be found in low altitude regions which have been geologically altered, especially by fire. Since they suffer disadvantages due to altitude, climate, and scarcity of soil substrate, pine forests do not tend to boast very rich biodiversity in flora. The Hispaniolan pine (Pinus occidentalis) is the most common tree in pine forests, but also found there are the agave (Agave antillanum), the palo de reina (Lyonia heptamera) and the pajón (Danthonia domingensis). Like the flora, fauna found in pine forests has been conditioned to the environment’s harsh nature and general lack of vegetation. The most representative birds in this type of ecosystem are the narrow-billed tody (Todus angustirostris), rufous-collared sparrow (Zonotrichia capensis), and the Hispaniolan trogon (Priotelus roseigaster).

Freshwater Wetlands:

These zones are characterized by the presence or absence of water during wet and dry times, respectively, and their proximity or distance from water. Freshwater wetlands and their vegetation are found in proximity to rivers, streams, ravines, and lagoons across Hispaniola. Within freshwater wetland ecosystems two types of woodlands are found: submerged aquatic vegetation and riparian forests. Indeed, freshwater wetland vegetation is the same as the vegetation found in areas surrounding bodies of water, except in dry forest communities. Plant species such as the gregorywood (Bucida bucera), sandbox tree (Hura crepitans), amacey (Tetragastris balsamifera), and the palo de viento (Didymopanax tremulus) are common here. Fauna found in these regions is typified by its relationship to the water. Commonly found freshwater wetland birds are various species of duck and heron, such as the pied-billed grebe (Podilymbus podiceps) and the great egret (Egretta alba). Some freshwater wetland reptiles are the Hispaniolan slider (Trachemys decorate) and the Central Antillean slider (Trachemys stejnegeri).

(Habitats of at-risk endemic mammals. Source: Atlas of Biodiversity and Natural Resources)

Services Provided by Ecosystems

Ecosystems directly or indirectly provide many benefits which humans harness to assure their sole and collective well-being. They are fundamental in the provision of goods and primary materials for our life, security, health, and social relations.

(What types of benefits do ecosystems provide? Source: Global Environment Facility project on re-engineering protected areas)

Services provided by ecosystems are classified in the following exhibits:

Provisioning Services

These consist of goods and services which can be obtained from ecosystems to satisfy individual and collective needs such as nourishment, primary materials for industry, the provisioning of water, and recreation.

(Ecosystem Provisioning Services. Source: Global Environment Facility project on re-engineering protected areas)

Cultural Services

Ecosystems generate innumerable benefits which are not easily quantified in monetary terms. For one example, they connect individuals and communities to which they pertain and mold community relations and their members’ perceptions about their surroundings.

(Ecosystem Cultural Services. Source: Global Environment Facility project on re-engineering protected areas)

Regulating Services

Ecosystems’ regulating services guarantee the ecosystem’s continuing ability to generate human-benefitting services. Self-regulation is essential for the stability of ecosystems.

(Ecosystem Regulating Services. Source: Global Environment Facility project on re-engineering protected areas)

Supporting Services

Known as basic support systems, these are fundamental to the ecosystems themselves as well as all other services which the ecosystem provides.

(Ecosystem Supporting Services. Source: Global Environment Facility project on re-engineering protected areas)

Legacy Services

These deal with conservation of an ecosystem in its peak state with the objective to have it pass from one generation to another. Their main benefit is in their non-use.