2011 International Year of Forests – Forests: natural areas at risk

This post is also available in: Dutch.

Aerial view of the Lovejoy project in Manau, Brazil.

Forests are at risk. Everywhere in the world. Also on Curacao. Television and newspapers often talk about impacts on forests, they are cut down, burned away, bulldozered, they are robbed of their plant and animal species and so forth. Terms such as loss of biodiversity, habitat destruction, degradation and erosion are all used when the threats to forests are illustrated. But what does this all mean? What does actually happen when a piece of forest is removed while many pieces still remain? And how does this influence our island?

One system

Forests are more than a collection of trees and plants. The intimate entanglement of trees, plants, epiphytes, parasites, soil organisms, humus, fungi, predators, prey, leaf eaters, fruit eaters, carnivores, and all the other relationships make a forest a ‘living organism’ which has a vital force, which breathes, reproduces and maintains itself. Take one element away or restrict the ‘super-organism’ and the system will slowly but surely start to collapse until nothing is left. Most people don’t realize that this is the main problem that nature has to face. The various dangers that impact a forest are certainly a problem for certain forest species or specific areas, but the biggest problem is the fact that the well-oiled system can no longer function.

Tom Lovejoy’s project

This first became evident because of a scientific environmental project designed by the biologist Tom Lovejoy as part of his studies of the driving forces behind the tropical rain forest in the Amazon. Lovejoy moved to Brazil in the sixties of the 20th century and has done pioneering work in unraveling  the ecology of tropical forests. What he wanted to know was what would happen in areas that became  isolated because of advancing forest destruction. Large pieces of Amazon were, and still are stripped of vegetation for agriculture. Here and there small pieces of rain forest were spared in between the various farms.  In here the animals that were driven out of the exploited forest found some sort of sanctuary. Lovejoy and his team of scientists set up a system of study plots in areas that were scheduled to be deforested. The plots were of different sizes ranging from areas of only one acre to areas of 1000 acres. All carefully protected and well studied since the early eighties. The main questions that Lovejoy wanted to answer with his experiment were: what is the limit of reversible decline of the rain forest?; what is the lowest limit for a working system?; what is the minimum critical size of an area of Amazonian rain forest? Valuable questions for conservationists around the world who were cracking their brains over what the minimum size of nature reserves should be. It is well enough to label a piece of nature as a nature reserve, but how big should the area be to ensure that the systems within such an  area can continue to function sustainably instead of slowly dying out? Is it better to protect a large piece of nature or should we protect lots of scattered little pieces instead?

Small areas are too small

During the experiment it quickly became clear that the small nature reserves, of one and 10 acres, completely lost their value. The major predators were the first animals to disappear, followed by other large vegetarian mammals. The amount of food was simply not enough to survive. Soon the monkeys left. The birds did things differently. Initially, the number of birds in the forest plots increased, due to the fact that birds originally occupying the now bare, deforested areas sought shelter in the reserves. But because of lack of food, and changing conditions in the small reserves, they soon left. Because of direct solar radiation and greater influence of the wind, humidity went down, it became hotter and drier. The trees located at the edges of the small reserves lost their leaves because of sunburn, the soil dried out so the roots could not keep a foothold and the trees fell down. Epiphytes disappeared and over time there was nothing left but an area of dead forest, where grass and other exotic plants coming from the agricultural areas flourished in between the dead stumps.

Aerial photograph of a section of the Amazon

But relatively large areas also …

But also within the larger reserves things began to change over time. The main observation was a steady decline in biodiversity. Simply put, species vanished. The reason is the fact that within a healthy  ecology there is a constant, albeit very slow, shift of species. Certain species go extinct, others take their place by traveling to the region in question from other areas. It may even happen that subsets of existing species will fill the gap left by the extinct species by adapting. These may, over time, turn into subspecies or, given enough time, even new species. This mechanism is caused by the accidental occurence of ‘errors’ in the genetic code of such species, called mutations, which very occasionally result into a beneficial change. The result of this process within a healthy piece of nature is a stable biodiversity, or even an increase in biodiversity. However, in the isolated areas which were part of Lovejoy’s  experiment extinction began to prevail, because substitute species no longer had the ability to populate the area. The emergence of new subspecies was also negatively affected because the areas were too small to effectively continue the mutation mechanism.

Although on Curaçao we do not have big predators, there are predators that must be taken into account. The birds of prey are our 'big' predators and usually require a large habitat to survive. Surviving is becoming increasingly difficult for the white-tailed hawk.

Small islands: sensitive to disturbance

The Lovejoy experiment is of great relevance to nature on islands like Curacao. In fact, the experiment was primarily designed to study how nature operates on small islands. Small islands are inherently sensitive to disturbance. The small surface area of these islands creates intimate relationships between flora and fauna and their environment, although precisely because of the small size the species richness and size of the populations is much lower than on the continents. This implies that the natural processes of extinction, restocking, and the emergence of new species and subspecies must be able to proceed as undisturbed as possible. However, humans have the tendency to decrease the already limited natural space to make room for what is seen as development, which will only accelerate species extinction. The natural resupply of substitutes is disturbed, while humans also introduce exotic species on a regular basis that will just cause chaos. Think of the red palm weevil, the lionfish, the pal’i lechi, the list is already quite long. If we want to keep our forests healthy then the conclusion can only be, that we should keep them as large as possible. To define a series of small nature reserves is pointless. Nature dies of setting boundaries.

About Michelle da Costa Gomez