Today is World Biodiversity Day

Photo courtesy of Namal Kamalgoda

Sri Lanka is home to about 900 species of vertebrates, about 960 species groups of invertebrates (mostly insects), 3,000 species of seed bearing plants and 1,750 species of lower plants. There are many more species to be formally discovered as well. Collectively we call them our biological wealth – the biodiversity of Sri Lanka. This remarkable diversity of animals and plants are found in yet another remarkable 39 major ecosystems, 24 edaphic (soil-related) variants and 30 human made ecosystems such as lowland rainforests, montane cloud forests, savana grasslands, floodplains, swamp forests, sand dunes, tidal mudflats and coral reefs.

Biodiversity matters to all of us

A large percentage of livelihoods had been sustained through this immense diversity as well. For example, there were nearly 1,300 fishing villages, over 180,000 fisheries households and about three million people employed in fisheries related livelihoods. Tourism and related livelihoods is another major aspect of how biodiversity helps our economy. Forests store more than half of the carbon found in terrestrial ecosystems. The blue carbon ecosystems such as mangroves, inter tidal flats, salt marshes and seagrass meadows, sequester carbon at two to four times more than that of tropical forests and are, therefore, critical in climate change mitigation. Montane forests are key for sustain large rivers, which provide water security for agriculture and drinking.

Fragmentation is the main threat

On an island of 65,000 square kilometers with a population of 22 million people, the life other than people must reduce, must shrink, compromise and cling to few oases to sustain. The protected area network that spans across the country provides that service through protecting our biological wealth. However, the protected areas are small, disperse and are increasingly utilized for human needs in the name of residential areas, farmlands, roads, and industry.

The conservation sciences show that the smaller the area the higher the risk of extinction of the inhabitants living in it (Figure 1). Therefore our protected areas, especially the smaller ones, are in danger of losing their diversity.

The reason behind that is that the smaller habitats, say a small forest patch, would harbor a smaller population of individuals for a given animal or plant. The smaller the number of individuals, the higher the risk of extinction. As a result, animals and plant living in such places face a greater risk of extirpation than that of animals or plants living in a larger forest.

Figure 1: The size of the protected area is proportional to the chance of survival of biodiversity (green Line) and it is inversely proportional to the risk of extinction (red line).

Over time the risk get even higher for biodiversity in smaller habitat patches as the conservation science (conservation genetics) show that the smaller populations lose their viability in a much faster rate than that of a larger population through time.

Figure 2: Smaller populations ( populations with 100 individuals) are at much higher risk of extirpation through time than that of medium (say 1,000 individuals) or large ( 10,000 individuals) populations.

When animals and plants became rare they started to lose their fecundity, meaning their reproductive fitness, or their ability to produce viable babies or seeds. As a result, the recruitment of new members to the population starts to drop as they get rarer. Eventually the population disappears. This is the reason that the biodiversity is being lost at a steady pace even in protected areas over the years. There are other contributing factors but the major reason is the extinction of smaller population living in such areas.

How can we stop this happening to our animals and plants? Can we increase the size of the protected areas? Can we increase the number of individuals of animals and plants in these areas? Such methods are possible only in limited situations and the conservation fraternity knows well that how hard it is even to maintain the present areas of the protected areas from encroachment, poaching and exploitation.

Is there a solution? Yes.

Connecting fragments via corridors

By connecting two existing small patches of forests, wetlands, grasslands and reefs through a narrow corridor we could double the size of the area for wildlife. The red curve of extinction in Figure 1 started to reverse as the area of occupancy increases – a magic in conservation planning. Therefore, simply connecting forest patches through corridors slows extinction. If several smaller patches can be connected to a larger patch through series of corridors, then the risk of extinction disappears even at a much greater scale.

How we create corridors of life?

A corridor can be a thin strip of habitat allowing safe passage for animas and plants from one habitat patch to another. It can come as a wildlife bridge over a highway, a simple canopy bridge over a small road (for butterflies, snakes, birds, and monkeys), an undisturbed strip along a tea plantation, an undisturbed bank of a stream or a river connecting habitat patches along its length or even a series of home gardens with suitable fruit trees and a space for safe passage. The width of such corridors can be as narrow as 20 to 30 feet to few hundred meters. The length of the corridor is the length between the two habitat patches that is expected to connect.

Studies have shown that such biodiversity corridors across the world help to preserve plants and animals through increasing their reproductive viability, genetic movement and providing safe passage to find mates, feeding areas and breeding areas.

Corridors reduce human animal conflict and save lives of both animals and people. They reduce crop damage and damage to human infrastructure, such as roofs, roads, vehicles and other commodities.

A national or regional scale programs initiated by either the government agencies responsible for conservation such as the Department of Wildlife Conservation and Forest Department, private sector parties through their CSR programs or environment organizations to created biodiversity corridors could immensely support the vanishing biodiversity of Sri Lanka. The beauty of this plan is that it does not need setting aside large areas as protected areas. It only needs some common sense and a bit of commitment.