Perbandingan Sifat Fisik Tanah Lintasan Sepeda Gunung Dan Tanah Hutan Di Hutan Pendidikan Gunung Walat, Kabupaten Sukabumi, Provinsi Jawa Barat

Abstract

Mountain bike track as along as 7.2 km was developed in Gunung Walat University Forest (GWUF) It was a part of development stragies of GWUF through sport-eco-tourism. Contruction and intensive utilization of mountain bike track in GWUF possibly cause changes in soil physical properties due to soil compaction, and increase the rate and amount of surface run-off and erosion. The objectives of this research are to analyze the physical properties of mountain bike track and forest soils, and to know the rate and amount surface run-off and erosion on mountain bike track in GWUF. Data collection and analysis were conducted from October 2010 until March 2011. The collected data consists of mountain bike tracks location, length, wide, area and slope steepness, types of land cover, soil physical properties, rainfall, surface run-off amount and rate, and sediment load. The location, length, wide, area, and slope steepness of mountain bike track were analyzed from mountain bike track mapping, overlaying with contour, land cover types, and soil types maps of GWUF using Geographic Information System software. Soil physical properties were analyzed through analysis of soil samples in the laboratory, except for the soil compactness was measured directly in the field using penetrometer. Soil samples were taken using the ring samples from mountain track bike track as well as forest soil at difference slope steepness, namely 8—15%, 15—25%, 25—40%, and >40%. Daily rainfall were measured using an automatic rain gauge. Amount of surface run-off and sediment loads were measured using erosion plot size of 1 m x 0.6 m. Rainfall, surface run-off and sediment load data are collected every day, during 30 days of rain events. The results of this research showed that the physical properties of soils of mountain bike track and forest were not different significantly. Surface run-off and erosion on mountain bike track were in the level of ”very low” hazard class. It means the rate of erosion was in the threshold of safe criteria. The highest surface run-off and erosion occures on the slope of 15-25%, those are 143.228,88 m³/ha/year and 206,74 ton/ha/year, respectively. Surface run-off and erosion are 187.424,42 m³/ha/year and 302,59 302,59 ton/ha/