Changing tropical hydrologic regimes have been attributed to conversion from tropical forest to agricultural use and are a threat to many tropical upland ecosystems. A series of experiments were conducted in headwater catchments of Matalom, Leyte, Philippines, to quantify the effect on the near-surface hydrology of land uses common to the steep slopes and thin, calcareous soils. Overland and subsurface runoff were collected to compare the surface hydrologic response of forested, tilled,slash/mulch, and pasture catchments. The forest site demonstrated the lowest annual runoff response, at less than 3 of rainfall, and the highest rainfall threshold which initiated runoff Conversely, the pasture site demonstrated the greatest annualrunoff response (76) with the lowest thresholds. A pasture with contour-hedgerows demonstrated greater infiltration than the pasture without this conservation practice, generating runoff at 31 of annual rainfall. The plowed and slash/mulch sites hadsimilar annual runoff responses, at 17 and 13 of rainfall, although the predominant flow pathway differed between these sites. Surface runoff accounted for the majority of runoff at the plowed and pasture fallow sites; whereas, interflow provided thelargest contribution to runoff at the slash/mulch and forest sites.
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