June 28, 2006

6-26 Bye-bye toads. And birds. And ...

Toad, Costa Rica, 6-26-06. Ė natashaSay youíre a bird. Or a toad. Maybe this toad. Sure, this one. You rely on the forest floor to provide your food and offer the sort of protection youíve come to expect from your coloring. If you stay still, predators and lumbering visitors may not see you at all. Your prey might not see you. You can have a pretty good life, for a toad, what with having a better chance of eating than getting eaten.

Youíd prefer a full grown forest. The best is a thick canopy with loads of decaying organic matter and treefall to hide in and provide habitat for your food. However, you might be all right on a coffee farm, particularly where the coffee is grown under shade. Itís not ideal, but itís livable. Then the coffee farm (la cafť finca) where you live runs into the recent and ongoing Coffee Crisis, as itís known wherever coffee is grown. The farmer that owns the land you live on is only getting $0.33/lb for coffee that sells for ten or twenty times as much in northern markets if itís sold by the pound, or maybe a hundred times more if itís sold in pre-brewed individual servings.

Toad hiding in plain sight, Costa Rica, 6-26-06. Ė natasha

If the farmer canít find some other source of income, a better market or a diversification plan, even the shelter of the coffee trees may be cut down. Most often, theyíre replaced by pasture for growing cattle. Even with the heavy rain and verdant growth, the land that used to hide and feed you, along with many birds, small mammals, insects and opportunistic plants, has been replaced with a pasture of non-native grasses that can only feed about one cow per hectare. If you were a toad or a bird, this pasture would look frightening and inhospitable:

Cow pasture, Costa Rica, 6-26-06. Ė natasha

You would much rather find somewhere to live or feed under a canopy more like the hills in the distance. Unfortunately, youíre going to be displaced, possibly without recourse, for one of these:

Costa Rican cow, 6-26-06. Ė natasha

Over the last 50 years, Costa Rica has gone from 80% rainforest cover to 27%, even with a 2% increase in forest over the last couple years due to reforestation and farm abandonment. Considering that about a quarter of the country is now held in some kind of national park or conservation arrangement, as well as the fact that more forest is intact in Costa Rica than in any other Central American country, that might not sound so bad. However, Costa Rica depends on hydropower and it hurts the country in the pocketbook when erosion fills a dam with silt. There are numerous social consequences, which Iíll probably elaborate on later, to whatís also an ecologically significant amount of forest damage.

Most of the cleared land goes for cattle grazing, even though Iím told that the land only supports about one cow per hectare (about 2.2 acres) without supplemental feed. Coffee takes about a year of nursing as a bagged seedling and another two years after planting in order to be productive though, so itīs a big investment of time and resources for increasingly uncertain returns. If youíre a farmer deciding how best to keep the family in food and clothes, the beef might not seem like a bad option. For local biodiversity, however, itís a disaster.

As Prof. Karen Holl and graduate researcher Rebecca Cole were explaining Monday, there are many problems with reforesting from pasture. First, you donít have a lot of seed dormancy in the wet tropics because the climate is usually about the same all year. This is in contrast to, say, an apple tree. If apple seeds didnít require a period of cold followed by warming and abrasion to germinate, an apple tree might drop fruit in the fall and have all the resulting seeds germinate just before the winter frost, which would pretty much be an evolutionary dead end.

Also, you have a lot of seeds in these forests that are dispersed by animals or birds that depend on diverse stands of forest for food and shelter. Seed dispersal of these plants and trees, usually those with larger seeds, drops off to practically nothing over open, grassy areas. A large part of restoring forest in this region is just to get some structure into the landscape. For one thing, itís cost-prohibitive to restore the 200 plus tree species that might be represented in a smallish patch of native forest. For another, once thereís tree cover present, the seed-dispersing animals are more likely to venture forth. This is even more important because the loss of large predators means that populations of smaller seed predators have expanded.

Tree cover of almost any kind also corrects the other major problem with reforesting pasture, which is that trees will shade out the sun-loving grass. The grasses in question are imported African grasses that present stiff competition for soil nutrients and grow tall enough to overtop native plant seedlings.

Still, both Holl and Cole recognize that for reforestation to progress, part of the equation is finding ways for local people to support themselves. Whether itís planning sustainable hardwood harvests, farm diversification or just restoring damaged land so that it can be passed on to the next generation, there are a number of ways for interested local farmers to earn a living and bring the forest back.

It seems to me that a common perception of the environmental science field is that people working in it would just like all the humans to go away. While some sensitive areas may require special protection and other areas may be unsuitable for certain uses, the people Iíve met and whose work Iíve read seem to agree that itís as important for a landscape to support humans as to support animals. Environmental scientists may not always write about these social considerations, but they sure seem to talk about them a great deal in person. Even groups like the Nature Conservancy expend a lot of their efforts looking at ways to provide for edible landscapes and sustainable economic development.

While there is a strain of popular environmentalism that seems to hold human extinction as an ideal, from all Iíve read and heard, itís a fringe thatís unconnected to the consensus of mainstream environmental science.

Posted by natasha at June 28, 2006 05:26 PM | Costa Rica | Technorati links |
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