喀斯特季节性雨林木本植物胸高断面积分布格局及其对地形因子的响应 / Responses of spatial pattern of woody plants’ basal area to topographic factors in a tropical karst seasonal rainforest in Nonggang, Guangxi, southern China
森林生态系统地上生物量的分布格局是物种分布格局的重要内容。局域尺度内因地形差异引起的生境异质性是地上生物量分布格局形成的环境基础。本文以弄岗北热带喀斯特季节性雨林15 ha动态监测样地2011年第一次普查数据中每木个体为研究对象, 尝试以每20 m × 20 m样方内所有个体及不同径级类群的胸高断面积之和为木本植物地上生物量的衡量指标, 利用广义可加模型对喀斯特季节性雨林中胸高断面积之和的空间分布格局进行研究, 定量分析了其对7个地形因子的响应。结果表明, 洼地、山坡和山脊3种生境类型中, 所有个体的胸高断面积之和山坡最高、山脊最低, 且山脊与山坡、洼地的差异均显著; 广义可加模型结果显示, 不同地形因子对胸高断面积之和的解释偏差差异明显, 其中海拔、坡向、凹凸度、岩石裸露率对胸高断面积之和的解释偏差依次降低, 而干旱度指数、坡度和地形湿润指数解释偏差相对较小。喀斯特季节性雨林木本植物胸高断面积之和空间分布的异质性及其与地形因子之间的关系, 反映了胸高断面积之和在地形因子对土壤、水分和光照等条件重分配影响下的多重响应机制及生长策略。
Spatial patterns of aboveground biomass are important aspect of species distribution patterns, whereas the environmental heterogeneity caused by the topographical differences in the scope of local scales is the environmental basis for the formation and evolution of this pattern in natural forest systems. In this study, we examined the spatial patterns of total basal area of woody plants, to quantitatively analyze the response mechanisms of the spatial patterns of total basal area to the seven topographic factors using a generalized additive model in a fully mapped 15 ha permanent plot in a northern tropical seasonal rainforest in a karst landscape in southern China. We used the total basal area of all the individuals and each DBH class in each 20 m × 20 m quadrat as a standard to measure the value of aboveground biomass of woody plants. Results showed that the hillside had the highest total basal area but the lowest was found at the ridge of the three habitat types. The total basal area of the ridge was significantly different between the hillside and the depression. Topographic factors had definite effects on the total basal area of woody plants, with the following sequence: elevation > aspect > convexity > rock-bareness rate (RBR) > altitude above channel (ACH) > slope > topographic wetness index (TWI). All topographical factors were statistically significant with the exception of the TWI and slope showing marginally significant. The relationships between the spatial variation of total basal area of woody plants and topographic factors reflected the response mechanisms and growth strategies of woody plants in a tropical seasonal rainforest under the effects of the redistribution of soil, water and light conditions.
Abstract in Chinese and English; article on Chinese only.