Ecoagriculture by Future Harvest & Sara J. Scherr

Author:Future Harvest & Sara J. Scherr [McNeely, Jeffrey A.]
Language: eng
Format: epub
ISBN: 9781610910620
Publisher: Island Press
Published: 2012-08-28T00:00:00+00:00

EXAMPLE 28. TREES IN COSTA RICAN PASTURES FEED FOREST BIRDS

Central America has more than 9 million hectares of land in silvipastoral systems (pastures with scattered trees). Depending on farm size and where a particular plot of land is in the fallow cycle, dispersed trees on farms may be established from an improved fallow, through strategic clearing of a mature fallow, or (where no fallow is used) through direct planting or protection of naturally regenerated trees (Kowal 1999). Farmers keep the trees intentionally in their pastures because of significant benefits to associated livestock, subsistence needs, and income benefits. It is estimated that in Central America as a whole, trees in pastures could produce 18.4 million cubic meters of timber per year, given adequate support for timber marketing and assistance to farmers in tree management (Beer, Ibrahim, and Schlonvoigt 2000). Research has begun to show that such isolated trees also play a critical role in maintaining wild biodiversity, by serving as nesting, feeding, and roosting sites for a variety of bird and bat species, many of which are forest species, and by providing transient habitats for many neotropical migratory birds. Remnant trees in pastures often retain rich communities of epiphytic plants that would not otherwise be present in the agricultural landscape. They assist in forest regeneration, both because they produce seed locally and because the birds and bats that visit their canopies regurgitate or defecate seeds of forest plants while perched in the trees. In addition, the microclimatic conditions (for example, low light levels and high humidity) beneath tree crowns help facilitate the germination, survival, and growth of forest plants.

A survey of twenty-four small-scale dairy farms near Monteverde, Costa Rica, found a mean density of 25 trees per hectare; primary forest trees accounted for 57 percent of all species and a third of all individuals. Many of the tree species are important locally for humans as sources of timber (37 percent), firewood (36 percent), or fence posts (20 percent). Timber, shade for cattle, fruits for birds, and fence posts were the most commonly cited of nineteen reasons for keeping the trees. More than half the farmers interviewed thought that the presence of trees in their pastures improved their farm productivity, whereas 32 percent felt the trees had a beneficial effect in the dry season (conserving moisture) but could be negative in the wet season if they produced too much shade. The remaining 13 percent thought the trees had no effect on productivity. The biodiversity impacts were significant. More than 90 percent of the species are known to provide food for forest birds, bats, and other animals. Their presence is especially important for forest birds (such as three-wattled bellbirds, resplendent quetzals, and keel-billed toucans) that seasonally move from the Monteverde Reserve Complex down to the Pacific lowlands. Since most of the landscape surrounding the Monteverde Reserve Complex is highly deforested, isolated trees in pastures provide essential food sources at various elevations along the birds’ migratory path (Harvey and Haber 1999).

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