The effect of tree species diversity on phosphorus availability and cycling

通过物种多样性森林保持土壤肥力，可能是热带地区大面积种植林的重要生态系统服务。在中国生物多样性论坛比较研究区的初步调查表明，土壤磷含量很低，大部分有效磷以有机形式存在，许多物种的叶和凋落物磷含量显示出磷限制。然而，磷组织浓度的高变化指向各种物种特异性的机制，以采取有限的磷供应。鉴于大范围的生物可利用的土壤磷化合物，和各种机制，植物可以访问P，我们假设共存的植物物种分区土壤有机磷，以减少竞争。在此基础上，我们假设：（a）土壤P在有效态中所占比例随样地树种多样性的增加而增加;（B）相邻树种多样性影响土壤P的形态和单株养分;（c）树种多样性对生产力的影响随土壤有机P源多样性的降低而降低（互补性降低）。此外，我们将探讨是否可以区分不同的土壤磷组分的基础上，他们的光谱特性，这将大大减少分析工作。

The maintenance of soil fertility through species diverse forests might be an important ecosystem service in tropical regions with their large areas of forest plantations. Preliminary investigations at the Comparative Study Plots of BEF China have shown, that soil P concentrations are very low, a large proportion of available P is in organic from, and that many of the species show of leaf and litter P concentrations that are indicative P limitation. However, the high variation of P tissue concentrations points to a variety of species-specific mechanisms to adopt to limited P supply. Given the large range of biologically available soil P compounds, and the variety of mechanisms by which plants can access P, we assume that co-existing plant species partition soil organic P to reduce competition. Based on this we hypothesize that (a) the proportion of soil P in available fractions increases with increasing tree species diversity of plots, (b) neighbourhood tree species diversity affects soil P fractions and nutrition of individual trees, and (c) effects of tree species diversity on productivity decline (complementarity reduction) with decreasing diversity of soil organic P sources. In addition, we will explore whether the different soil P fractions can be distinguished on the basis of their spectral properties, which would greatly reduce analytical efforts.