ESTIMATING TRAIL-RELATED SOIL-EROSION IN THE HUMID TROPICS - JATUN-SACHA, ECUADOR, AND LA-SELVA, COSTA-RICA

Using McQueen-type portable rainfall simulators, we simulated rainfall on trail surfaces and adjacent, off-trail forest sites at two reserve s in the humid neotropics. Our results confirm that rates of runoff ge neration and soil particle detachment are significantly higher on trai ls and that runoff occurs frequently on trails, but only rarely off-tr ail. We estimate that 15 mm of rain falling in 30 minutes would detach 3186 kg . km(-2) of soil from trails at Jatun Sacha (11 . 10(4) kg . km(-2)) and 4716 kg on trails at La Selva (6.0 . 10(4) . kg . km(-2)). Off-trail, the same rain would detach 0.075-1.1 . 10(4) kg . km(-2) a t Jatun Sacha and 0-1.1 . 10(4) kg . km(-2) at La Selva. The high eros ional potential of rainforest trails underscores the need for careful management of ecotourism and other trail-dependent rainforest activiti es.