2011 International Year of Forests – a forest through a magnifying glass

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Seru Gracia, evergreen vegetation

Forests come in all shapes and sizes. On every continent except Antarctica, there are forests. But – logically – the types of forests and their associated characteristics and appearance differ in various parts of the world. Rain forest is found in tropical Central and South America, deciduous forest in Europe and coniferous forests in the colder regions of the world. Nothing is what it seems, though. Especially in the case of forests you will often see differences between patches of what initially appears to be the same forest type within one country. This all depends on the various micro-climates within a country. If we assume that the Curacao ‘mondi’ is characterized by a type of forest that usually contains few large trees and is dominated by thorny plants, are there then different forests on our island? The answer is: absolutely!

Rocks and vegetation

Biologically, a distinction is made between different types of vegetation on our island, and thus between different types of forests. The distinction is closely related to the geological composition of the soil on our little island. Most people are convinced that only limestone and what is known as diabase can be found on Curacao, but that is not true. The geological history of the island is much more complicated. The rocks found on the island are classified within four geological formations: the rock formation that is popularly known as diabase, a submarine erupted volcanic rock we should officially refer to as basalt. This is the oldest rock package on our island. A little younger is the Knip-formation, a very distinct package of layered rock that occurs only at and around the Christoffel mountain and Knip.  The next package is the Middle Curacao formation, comprising of redeposited erosion remnants of older rocks. Last but not least there is the youngest formation, the limestone rocks, including the beautiful limestone terraces along the north coast, which consist of the fossilized remains of ancient coral reefs.

The mechanisms of formation of these rocks will be described in another series. What is important now is that all these rocks have different chemical compositions and physiology. This fact is one of the reasons that there are many different conditions on our little island of only 444km² surface area, in spite of the fact that the mean levels of rain are basically identical for all areas, as well as the air temperature.

Limestone vegetation near the Spanish Water

The vegetation groups on Curacao

Within the “Concept Nature Policy plan for Curacao”, a plan which has been prepared by various government agencies and other organizations more than 10 years ago (unfortunately without being implemented yet), in order to establish a framework for managing and preserving natural areas, the local forests are divided, on the basis of mainly geological data, into the following four groups: Diabase seasonal vegetation group, Knip formation evergreen vegetation group, Limestone evergreen vegetation group, and mangrove forests. The names indicate more or less what the characteristics of these groups are.

Diabase seasonal vegetation group

This group, which is found mostly in the central parts of the Banda’bou and Banda’riba regions, is the  group most “burdened” by the climate on the island. During hot and dry periods, the vegetation within this group will turn gray and brown and looks as if it’s dead. But once the rains come, even if only a few droplets, the ‘dead’ vegetation instantly transforms into rich green vegetation, and in no time flowers and fruits will be produced.

Knip formation evergreen vegetation group

This group, which occurs in and around the Christoffel Park, will always look green. Whenever you go there, even during times of severe drought, the vegetation within this group will never look as barren and dry as elsewhere on the island. The reason for this is, that Knip-rocks are efficient water storage reservoirs. Rainwater is absorbed and collected in those water reservoirs that will supply the vegetation with the necessary water even when the rainy season has passed for some time. Knip-rocks are also resistant to erosion because of a high relative hardness, hence the Knip hills will stay higher in elevation than other areas. The highest mountain on the island, the Christoffel Mountain, is proof of this mechanism. Because of the altitude, the humidity in this region is higher than elsewhere on the island, which again facilitates the survival of plants. Where high humidity is present, the environment is also more humid. There you’ll encounter plant species specially adapted to collect a maximum of moisture from the air.

Melocacti (Turk's cap cactus) grow mainly on limestone. The roots of the plant will dig and swarm around in search of moisture. Often the plants are removed to be placed in gardens. A bad idea. It is impossible to extract all the roots and this damages the root system of the plant beyond repair. After a year or two the plant will die all the same.

The Limestone evergreen vegetation group

This group is located around the edge of the island where the limestone terraces are located. Limestone is not only highly susceptible to erosion, the character of limestone is such that gaps and fissures between the diversity of fossil corals and other animal are part of the structure of such rocks. Erosion will increase the size of the cavities. During a downpour these rocks will suck up water like a sponge. There will always be at least partly filled water reservoirs present within these rocks. Plants growing on top of these rocks will therefore always find water somewhere, and they will remain fairly green throughout the year. The root system of these plants is very extensive. That is the main reason why plants living on limestone rocks are almost impossible to transplant.

The mangrove forests

The last group consists of mangrove forests, plants very well adapted to the difficult circumstances of salty shores that sometimes even thrive while directly positioned with their roots in salt water. On the island only a few places are home to mangroves, and there they will only occur in narrow fringes.

If you take a good look at all the different vegetation groups, you will notice some tree species that will grow at almost all locations. A good example is the Wayaka. The tree can thrive anywhere except, naturally, within the salty mangrove forests. You’ll find them from the jagged limestone terraces on to the slopes of the Christoffel mountain. They only will look different in every location.

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