Cover Image
close this bookDiversity, Globalization, and the Ways of Nature (IDRC, 1995, 234 p.)
close this folder5. Grasslands
View the documentSavannas
View the documentThe temperate grasslands
View the documentModifying grassland ecosystems
View the documentEnvironmental balance in grassland ecosystems

Environmental balance in grassland ecosystems

The balance of the effects (actual and potential) of globalization in the grasslands is unfavourable. Most savannas are the result of the degradation of forests. Although their soils are fertile, the fertility is often inherited from the former ecosystem and is substantially lower than it would be for a climatic savanna. Continuous farming on savannas gradually reduces fertility and, unless fertilizers are applied, agriculture becomes unproductive. In many cases, the use of fertilizers makes farming uneconomical and savanna lands are abandoned for other uses, usually raising cattle or planting with exotic trees, further unbalancing the ecosystem. Where slopes are steeper, the soft, highly friable savanna soils are easily eroded, further reducing their productivity.

These ecological changes bring about important geomorphologic and hydrologic changes. Gullies and ravines are formed by erosion, and stream-flow patterns become irregular (more severe droughts, increased frequency and intensity of floods). Navigation canals may be blocked by sediments, dams and reservoirs may become useless (or their life span may be considerably reduced), water intakes may became clogged, water-treatment plants become more difficult and costly to operate, and so on.

Envionmental degradation of prairies is also frequently the result of increased runoff, soil erosion, and related geodynamic phenomena. In addition, there is a growing risk of soil deterioration as a result of care’ less forestation.

The belief that “planting trees is good” does not necessarily hold in grassland areas, where forestation may bring about an ecological imbalance that may end in a substantial reduction not only in productivity, but also in the system’s biodiversity. As in other ecosystems, the sustainability of grasslands depends on recognizing the value of their diversity. It is through its resource base that the system can maintain the flexibility it needs and the potential for sustained use in the future.