Phosphorus cycling in grasslands and forests of differing diversity and land use

随着植物多样性的增加，养分的开发日益有效，导致土壤溶液中的养分浓度较低。这已经在N上表现出来，但对于其他重要的营养物质，如P，则没有。在受管理的生态系统中，多样性与土地利用强度和历史密切相关。要了解土壤中养分浓度的控制，必须将土地利用和生物多样性的影响分开。因此，我们建议研究土地利用和生物多样性对三个生物多样性试验区草原和森林系统磷循环的影响。我们的目标是理清土地利用和植物多样性对1)土壤中的P(总的、无机的和有机的)，2)土壤中P的释放(P矿物的溶解和有机质的矿化)，以及3)植物中P的影响，在所有深入研究的亚区(草地和森林)。此外，我们将利用新的同位素技术，即测定磷酸盐中的d18O，来评估土地利用方式对土壤中磷的影响。我们将测定土壤和植物生物量中的磷库，通过溶解和矿化释放的磷，以及从土壤中提取的磷的同位素特征(D18O)。

Increasingly efficient nutrient exploitation with increasing plant diversity results in lower nutrient concentrations in soil solution. This has been shown for N but not for other important nutrients such as P. In managed ecosystems, diversity is closely linked to land-use intensity and history. To understand the controls of nutrient concentrations in soil the land-use and biodiversity effects must be disentangled. Therefore, we propose to study the effect of land use and biodiversity on P cycling in grassland and forest systems of the three biodiversity exploratories. Our objective is to disentangle the effect of land use and plant diversity on 1) P in soil (total, inorganic, and organic), 2) P release in soil (dissolution of P minerals and mineralization of organic matter), and 3) P in plants in all intensively studied subplots of each exploratory (grasslands and forests). Furthermore, we will assess the influence of land-use practices on P in soil by using novel isotope techniques, i.e. the determination of d18O in phosphates. We will determine P pools in soil and plant biomass, P release by dissolution and mineralization, and the isotopic signature (d18O) in phosphate extracted from soil.