摘要
The soil conservation strategies adopted in the catchments of Shiwaliks,the most fragile region in the Himalayan ecosystem,failed to serve their purpose after a few years of their execution.A study was carried out in four differentially-treated catchments to monitor the variation in runoff and soil loss.The treatments imposed during 1988 included fencing,planting native vegetation and engineering structures in catchment I;planting native vegetation and fencing in catchment II;fencing alone in catchment III in addition to an untreated catchment IV.The soil loss during the initial years(1989–1995)of imposition of the treatments was lowest(25.2 t ha^(-1))in catchment I,treated to the maximum extent and highest(43.3 t ha^(-1))in untreated catchment IV.During the later period(1996–2006)the trends reversed,i.e.,catchment IV recorded the lowest(14.1 t ha^(-1))soil loss whereas catchment I recorded the highest(23.4 t ha^(-1))soil loss despite the fact that there was no change in the status of soil conservation or the characteristics of the catchments.The runoff was 71%higher in untreated catchment than in treated catchments initially and this difference decreased to 27%during the later period.
