Urban or rural fragments: which soil use in forest surroundings induces greater litter deposition?

摘要

The soil use in surroundings of forest remnants, as well as, variations in seasonality and rainfall totals from each year might influence the composition, structure, and ecophysiological responses of vegetation and, thus, cause differences in litter deposition. For this reason, the present study proposes to verify which soil use in the surroundings of forest fragments induces greater litter deposition. Study areas were defined after mapping and quantification of urban and rural occupations around the remnants (buffer up to 3 km), based on satellite images. In each fragment were installed 36 collectors of 0.25 m(2). Litter deposition after 2 years was 434.73 t in the urban fragment and 513.32 t in the rural area. GLM analysis showed that the total litter mass and fractions (leaf, twig, and seed) were significantly higher in the rural fragment and dry season, excepting for the seed fraction in the urban area, which did not present seasonal variation. Simple Linear Regression test showed that leaf deposition in the rural and urban fragments increased with the reduction of water availability, and increasing in seed deposition was also observed with the reduction in precipitation in the urban fragment. Our results suggest that soil use in the rural fragment vicinity may have provided changes in the local abiotic characteristics within the rural fragment which should have induced a greater intensity in litter deposition. Therefore, the sugar cane monoculture surrounding the rural fragment induced the greatest intensity of litter deposition, and possibly reflects the effects of the fire use on sugarcane management.