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凋落物是森林生态系统的有机质和养分储藏库,是土壤和植物间物质交换的枢纽,是森林土壤肥力的主要来源之一。本文选取弄岗喀斯特季节性雨林15 ha森林动态监测样地中布设的90个凋落物收集器自2014年3月至2015年2月收集的6个常见种的凋落叶,结合2014年7月沿海拔梯度(185–368 m)采集的50个土壤样品,研究了土壤和凋落物的C、N、P化学计量学特征及其沿海拔梯度的变化趋势。结果表明,除P含量在高坡位及峰顶较低外,土壤中的C、N、P含量均达到了全国第二次土壤普查分类标准中的一级水平;土壤的C、N含量及C:P和N:P与海拔呈正比,P含量和C:N与海拔呈反比。因本文采样的海拔差异较小,推测上述土壤养分含量与海拔的关系主要是由于微地形引起的土壤差异而不是海拔差引起的气象因子差异所致。与其他森林生态系统相比,这6个常见种凋落叶的C、N、P含量的平均值呈现出高C和N、低P的格局;而不同海拔凋落叶的C、N、P并未表现出类似土壤中的变化规律;6个常见种凋落叶均表现出春季较高的C含量和夏季较高的N、P含量。虽然桂西南喀斯特季节性雨林中土壤的C、N、P含量总体水平较高,但其单位面积内的胸高断面积之和却远低于其他森林生态系统,表现为生物承载量较低;受个体生长环境差异的影响,同种凋落叶的C、N、P化学计量学特征可能会存在个体间差异。研究结果将为我国西南地区典型喀斯特生态脆弱区的生态功能恢复与植被重建提供科学依据。
Litter is the organic matter and nutrient reservoir of forest ecosystem. It is the hub of soil and plant matter exchange and is one of the main sources of forest soil fertility. In this paper, we selected six litter of common litter collected from 90 litter collectors in the 15 ha forest dynamic monitoring plots of the Nonggang Karst seasonal rainforest from March 2014 to February 2015, Fifty soil samples collected from the gradient (185-368 m) were used to study the C, N and P stoichiometry of soil and litter, and the trend of elevation along the gradient. The results showed that the content of C, N and P in soils reached the first level in the second national classification standard of soil survey except for the high content of P and the low peak. The content of C, N and C: P and N: P are proportional to altitude, P content and C: N are inversely proportional to altitude. It is speculated that the relationship between soil nutrient content above sea level and altitude above sea level is mainly due to the soil difference caused by microtopography instead of the difference of meteorological factors caused by altitude difference. Compared with other forest ecosystems, the average C, N, P contents of these six common litter showed the pattern of high C and N and low P, while C, N and P of litter at different altitudes were not Which showed a similar pattern of changes in soil. The six common litter showed the higher C content in spring and the higher N and P content in summer. Although the overall C, N and P contents of soils in the Karst seasonal rainforest in Southwest Guangxi are higher, the sum of the areas of the thoracic and pachydermatic areas within the unit area is much lower than those of other forest ecosystems, showing a low biocapacity. Individual differences in the growth of the environment, the same litter of C, N, P stoichiometric characteristics may exist in the individual differences. The results will provide a scientific basis for ecological restoration and vegetation reconstruction of the typical karst ecologically fragile areas in southwestern China.