干湿度梯度及植物生活型对土壤氮磷空间特征的影响

Effects of Humidity/Aridity Gradient and Vegetation Form on Spatial Characteristics of Soil Nitrogen and Phosphorus in China

通过对我国土壤氮磷含量及化学计量比值的分布特征研究,探讨了湿度梯度与植物生活型对土壤氮磷空间分布的影响。研究结果表明:中国陆地系统自然土壤氮、磷含量及氮磷比分别在0.02~8.78 g/kg,0.05~1.73 g/kg和0.06~9.85范围内变化,地形和气候因素对其空间变异性的影响均较为显著。干湿度梯度分带对土壤氮含量和氮磷比值的影响较磷含量更为明显,氮含量与氮磷比呈现出明显的梯度变化特征,表现出湿润区>半湿润区>干旱区>半干旱区的规律,而磷含量变化不显著。在不同生活型植被土壤中,森林土壤氮磷的变化规律较灌木和草本土壤更为复杂;其植物磷平均含量低于全国平均值,说明森林生态系统植物受磷元素的限制作用与其较低的土壤磷含量供给有关。土壤氮磷含量和氮磷比与年均降水量和年均温度的相关性及逐步回归分析表明,土壤氮磷及其化学计量的变异性主要是受降水的影响。

In this paper, the impact of humidity/aridity gradient and vegetation form on the spatial distribution on soilnitrogen （N） and phosphorus （P） contents and N ： P ratio in China were discussed. The results showed that N and P contents andN ： P ratio of natural soil of terrestrial ecosystems in China were 0.02-8.78 g/kg, 0.05-1.73 g/kg and 0.06--9.85, respectively. Thespatial variabilities of N and P contents and N ： P ratio were further significantly influenced by topography and climate.Humidity/ aridity gradient had greater effect on N content and N ： P than on P content. N content and N ： P showed obviousgradient change characteristics with an order of humid region 〉 semi-humid region 〉 arid region 〉 semi-arid region, while Pcontent change was not significant. The variations of N and P in forest soil were more complex than those in shrub and herb. Theaverage content of plant phosphorus was lower than the national average, may indicating forest ecosystem limited by P isattributed to low soil P content. Correlation and stepwise regression analyses proved precipitation controls the variation of N andP contents and N ： P ratios.