Biodiversity; its benefits to people and the environment
‘Biodiversity’, or biological diversity, refers to the variety of plants, animals and microorganisms that exist, the genes they contain and the ecosystems they live in.
Living in the lowland tropics we are blessed with abundant biodiversity. Tropical areas are known to have more species per unit area than temperate areas and biodiversity decreases with increasing altitudes. Consider, for example, the mixture of species in our forests compared with temperate forests which tend to be dominated by one species, and compare our Main Ridge with, as an extreme, the snow swept Alps.
The status of our biodiversity in Tobago, as elsewhere, has always been dynamic. Over millions of years, under natural conditions, some species have increased in variety or numbers and others have been reduced or lost. Some people wonder why we should be worried about conserving biodiversity now, in particular, when the world has gone on more or less as it is for so long. But natural habitats everywhere are being assaulted as never before and as habitats are lost we are also losing various types of plants and animals. No one would have thought, even a few years ago, that the common house sparrow of Britain could be endangered, but now it is. With the rapid changes we are seeing in Tobago, there are concerns that man-made changes to our environment are leading to too many of our species being lost and our biodiversity becoming seriously depleted.
One of the reasons biodiversity is important is because it helps to keep the environment in a natural balance. An ecosystem which is species-rich is more resilient and adaptable to external stress than one in which the range of species is limited. In a system where species are limited, the loss or temporary reduction of any one could disrupt a complex food chain with serious effects on other species in that same system. Once biodiversity is sufficient, if one nutrient cycling path is affected another pathway can function and the ecosystem - and the biological species it supports - can survive.
Elsewhere, tropical rainforests, in particular, have provided many beneficial products, from natural medicines to biological control agents for agriculture . It is not unrealistic to think that Tobago bush medicines, which are often treated as weeds, may have the potential to benefit the world one day so it would be irresponsible to allow this, as yet undefined, potential to be destroyed.
We also need a wide variety of plant species, in particular, to continue to feed us. Today, relatively few cultivated crops feed most of the world’s population; rice corn and wheat are the three main staples - a surprisingly small number. Scientists need to use the "wild" gene pool, and are concerned that it is diminishing, to improve or expand on the limited number of food species by breeding in factors such as disease resistance, drought tolerence or productivity. Once we have access to a wide variety of species and genes within those species , we have an invaluable resource that can be used to meet the changing needs of the worlds population in many ways, by using techniques such as selective breeding crossbreeding or even genetic manipulation, but we must keep our options open by conserving as big a gene pool as possible.
We need to preserve as many individual species as we can and we also need to preserve as many different types of ecosystem as we can, because each one serves a different and important function.
Wetlands, for example, are a spawning ground for many of our fish, they act as feeding and breeding grounds for many spectacular birds and they serve as a natural filter for pollutants. Our forests provide natural vegetation cover which helps to create water catchments, regulates excessive water run off and protects us from the extremes of droughts or floods. If we lose our natural cover, water yield and quality would be reduced , the soil would be leached of nutrients and our precious topsoil lost as silt in the sea. Tobago’s marine envionments and ecosystems are as diverse as those on land and must also be preserved to ensure that our marine environment stays clean and attractive, as well as feed us and generate income for fishermen and divers. We must ensure they all survive the onslaught of development because we need them all.
We should also not underestimate the importance of the simple aesthetics of conserving biodiversity. A biologically diverse environment is usually very beautiful, and endlessly fascinating. Preserving Tobago’s natural environment and all the wonderful variety of species within it will benefit our economy because visitors who enjoy the unspoiled nature of Tobago, the birdwatching and the wildlife, will keep coming back - but isn’t it even more important to preserve it for our own benefit and for our children’s enjoyment?
To be able to monitor what we are losing, or are in danger of losing, we should inventory, as far as possible, what we have. Environment Tobago is working with the University of the West Indies and other researchers on a pilot project, which involves a census, itemising every species encountered, of plants, birds and insects on Little Tobago. This work should eventually be extended to the rest of Tobago, giving us hard data on what our biological resources are and where our strengths and weaknesses lie.
David Hardy, of the USA, has tried to bring together all the scientific work ever published on the biology on Tobago’s diverse species. This is a tremendous contribution, but there is still a lot more work to be done on identifying species found here to know whether they are native to Tobago, whether they are unique to Tobago and what is the status of their populations.
The conservation of biodiversity is a very pertinent issue at this time when concerns about preserving Tobago’s environment and biodiversity appear to conflict with pressing economic and social concerns.
· Will hotel development destroy our wetlands, which in turn would deplete our rich marine environment?
· Will destroying the birds which are agricultural pests eventually eliminate them altogether?
· Hunters need to make a living, but are they decimating the very animals they need to hunt?
· Housing, industries and recreational facilities are needed but which habitats will be sacrificed in the process of providing these?
· Are unchecked sediments and effluents from development projects already affecting the quality and quantity of our marine species ?
· There is worldwide concern that fish stocks have become depleted. Do we know what the status of our fisheries resources are and how long they will last?
There may be no easy answers, but these, and other issues, must be addressed with wisdom and concern, not just for the fast dollar today, but also for Tobago’s natural biological wealth that we should leave for others tomorrow.
Dr. Pamela Collins