Indigenous Crops or Colonoss Cattle? Soil Organic Carbon of Forest-to-Crop versus Forest-to-Pasture Land Conversions in Eastern Panama
Heger, Martin Philip
The forest of Eastern Panama is converted to agricultural land predominantly for two purposes: cultivating crops and ranching cattle. This article studies the relative soil quality impacts of indigenous forest-to-crop conversion versus non-indigenous forest-topasture conversion. Soil organic carbon (SOC) concentration levels are measured in forest, crop, and pasture sites to allow for comparative evaluation of land use change impacts. The preponderance of evidence in the literature points to a substantial decrease of SOC following forest-to-crop conversion, but no change in forest-to-pasture scenarios. Studying indigenous crop cultivation techniques, and smallholding colonist cattle ranching activities, this article finds the opposite trend. Indigenous rice and maize fields are shown to not store significantly less SOC than forest sites. Non-indigenous colonist pasture sites on the other hand do store significantly less Carbon. The results vary substantially with topography. Deforestation on plateaus has particularly adverse effects on SOC, whereas the effects on other slope positions are minor and statistically negligible. The older the pasture sites get, the more SOC they lose, up to almost half of the original Carbon concentration 20 years after conversion. By the same token however the paper finds evidence that this is reversible and that if allowed to re-grow, secondary forests will revert back to original SOC levels.
Event: Annual World Bank Conference on Land and Poverty 2015
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