While most conservation planners focus on preserving certain areas, new research shows that an area's surroundings may be just as important. Specifically, ant diversity near forest fragments is higher in shade than in sun coffee farms, and salamander abundance is higher in disturbed streams that are confluent with undisturbed streams.
The need to include the "outside" in conservation planning is highlighted in a pair of papers in the February issue of Conservation Biology.
"We propose that the matrix within which habitat fragments occur is of equal importance," say Ivette Perfecto and John Vandemeer of the University of Michigan in Ann Arbor in the first paper.
The researchers determined the diversity of ground-foraging ants in and around La Montanita, a 37-acre tropical mountain forest reserve in southern Chiapas, Mexico. They used ants as an indicator of biodiversity because insects are the most diverse group of species and ants comprise most of the insect mass in the tropics. The reserve is a forest fragment that lies between two types of coffee farms: a shady, organic farm overplanted primarily with native trees, and a sunnier, conventional farm that uses pesticides and herbicides.
After petroleum, coffee is the most-traded commodity in the world and coffee plantations have replaced much of the tropical mountain forest, fragmenting what remains into small patches. One of the keys to conserving broken-up habitats is making sure that species can still travel from fragment to fragment. The ants, for instance, need to fly among forest fragments to establish new colonies.
Perfecto and Vandemeer found that while the number of ant species was
similar in the forest fragment and the shady, organic farm (23 vs. 16),
it was much lower in the conventional farm (7). They also found that
while ant diversity on the farms decreased with distance from the forest
fragment, this dropoff was