Spatial distribution patterns of vegetation and soil carbon density in fenced and grazing grassland.
2011, 30(12):
2739-2744.
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Taking a 13-year enclosed and grazing alpine Kobresia humilis meadow as test object, an investigation was conducted on the vegetation and soil carbon density at different distances from the entrance to the inside of the pasture. From the entrance to the inside 50 m, at inside 60-180 m, and at 200-300 m, the carbon density of existing vegetation was averagely 1298.0 g C·m-2, 997.3 g C·m-2, and 1285.5 g C·m-2, respectively, and the carbon density of net primary production had the same variation trend, i.e., averagely 742.5 g C·m-2 at 0-50 m, 571.0 g C·m-2 at 60-180 m, and 745.7 g C·m-2 at 200-300 m, which was related to the foraging frequency and grazing intensity of sheep. Generally, in the central zone of the pasture, the grazing pressure was stronger, and the foraging time of sheep was longer. In contrast, owing to the effects of fencing or of the environmental factors outside the fence, the grazing intensity near the fence was relatively weaker, which,to some extent,played a protective role on the vegetation growth in the enclosed pasture, and eventually, led the vegetation carbon density to increase. From the entrance to the inside of the pasture, soil carbon density showed a complex pattern, i.e., increased from the entrance to the inside 100 m, decreased at 100-170 m, and increased slightly at >170 m, with the maximum value (15.42 g C·m-2) at 95 m and the minimum value (14.12 g C·m-2) at 170 m. It remained unclear why this pattern occurred, but one of the reasons could be that the dynamic transformation process of soil organic matter was affected by many factors, and compared with vegetation carbon density, this process would have a certain hysteresis, which should be further studied.
