August 1, 2004
"East and Western Forests"
by Laurel Redding

A couple of weeks ago, Sean, Alberto and I decided to take a small side-trip down to the rainforest at the Andasibe-Perinet-Mantadia complex. Andasibe is about a two and a half hour drive east of Tana, and a very different environment from the forests of our research site in Ankarafantsika in the north-west part of the country. While one of the objectives of our trip was to see the famed indri - the largest of the lemurs, whose eerie territorial calls penetrate the forest - our trip was also the perfect opportunity to see a whole new type of forest.

We visited two forests during our trip. The Perinet Indri reserve, which is similar to our JBA (Jardin Botanique A) forest - more secondary forest, more ecotourist-catered with many well-hewn paths and approximately known locations of animals. Mantadia, on the other hand, is the forest less visited by tourists, consists of more primary forest, much less worn - at times, nonexistant - paths, and more closely resembles our primary forest JBB (Jardin Botanique B). Noticeable in both Eastern and Western forests was the presence of invasive species of trees - eucalyptus trees in our Eastern forest, and both eucalyptus and pine in the western rainforests.

There, however, ended the differences between our Eastern forests and the Western forests. The western forests are wet rainforests, while the eastern ones are dry, deciduous forests. They are separated by high plateaus that run in a north-south line in the center of the country. The vegetation in the rainforest was much more dense, more green and much more heterogeneous then the forests in the east which are more openly-spaced, less dense and more homogeneous. The size of vegetation also differed. The rainforest was characterized by enormous ferns, palms, fungi, even enormous orchids, while an eastern forest like JBA has an abundance of smaller plants, such as vines, bushes, and thinner and shorter trees.

The wildlife was reflected in this difference as well. The general rule is that in a more heterogeneous forest, there wil be a larger number of species but found at lower densities. More homogeneous forests are characterized by fewer species, but found at higher densities. Our first day, we hiked for five hours in the morning through the Mantadia complex - the more untouched, pristine of the forests - and saw virtually no animals: a bird or two and some insects (although in the afternoon we saw bamboo lemurs, indri and diademed sifakas). In the Eastern forests, on a typical 1.5-2hr trap check, it is typical to see at the very least, five species of birds, snakes, lizards, insects, lemurs...

Several other differences stood out as well. The forest in Ankarafantsika is not only less dense, but less continous. JBA touches a wide expanse of savannah and is adjacent to a large (and growing!) lavaka - literally a small canyon of erosion. The savannah houses a couple of small fragments of forest as well, but they are, for the most part, islands in the middle of the savannah. The rainforest seemed much more continuous - even on the drive to Andasibe, it was hard to tell where the forest ended, the hills were so covered with trees!

Another blatant difference I noted was the absence of scats in the rainforest. In Ankarafantsika, everywhere we go we see scats on our trails - fossa (when we're lucky!), bush pig, wild cat, a very large number of zebu scats, dog scat, even human scats! The rainforest, perhaps because of its thicker vegetation, afforded no such reserve of scats and certainly no trace of zebu could be seen. These two facts, might, in addition, have a disturbing implication for the quality of management and protection given to each of these protected areas.