Factors controlling phosphorous availability and their relevance for phosphorous nutrition of forest stands

控制磷有效性的因素及其与林分磷营养的相关性

• 批准号: 241239807
• 负责人: Professor Dr. Jürgen Bauhus
• 金额: --
• 依托单位: Forstliche Versuchs- und Forschungsanstalt Baden-Württemberg (FVA)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/241239807?language=en
• 关键词: Factors; controlling; phosphorous; availability; their

1. RationaleDuring the development of forest soils phosphorus (P) commonly declines in both abundance and availability and thus becomes limiting for biological activity. Forest ecosystems adapt to this process by developing efficient P recycling mechanisms, including the formation of stable P-stores and optimized P uptake by trees. In Central Europe, this sensitive evolution is disturbed by an accelerated soil acidification driven by anthropogenic deposition. The fast decrease in P nutrition observed in various forests supports this hypothesis.2. ObjectivesThe project examines for Norway spruce and European Beech, how P uptake and mobilization efficiency increase along a soil ecological gradient ranging from “young” soils with high plant availability of P in primary minerals to “aged soils” with reduced availability of mineral P. We are further interested in i) the influence of physical and chemical boundary conditions on the efficiency of P-recycling, i.e. maintaining P availability for trees while minimizing P-leaching, and ii) how artificially accelerated acidification through nitrogen (N) fertilization or enhanced acid buffering through experimental liming will vary, or possibly disturb P uptake and mobilization efficiency. We want to assess the following competing processes i) storage / fixation of P in the soil, ii) P export with the seepage water and iii) mining of the soil P resources by the tree through interactions between roots and mycorrhizal hyphae with the mycorrhizosphere soil. All three processes display pronounced spatial heterogeneity in natural forest soils, which we aim to maintain in our experiments to such an extent that their relevance at ecosystem level can be assessed.3. Material and MethodsMesocosm experiments with soil from SPP core sites and 1 to 2 year old spruce and beech seedlings will be carried out in the greenhouse: i) changes in plant uptake and percolation loss in relation to total and labile P pools along a P depletion gradient will be assessed in naturally structured soil columns, by measuring composition and distribution of P-species in the soil, Pfluxes in the soil water, and plant P uptake. Separate treatments with and without inclusion of an organic surface layer aim at assessing the relative role of organic and mineral soil for P nutrition. The disturbance by liming and N fertilization is studied for the two extreme sites of the acid P depletion gradient. ii) The impact of aggregate structure and aeration in mineral soils on P uptake and mobilization efficiency is studied by comparing naturally structured soil from the B horizon of one acidic site with sieved soil at different matric potentials. iii) Experiments with sieved soil from the main rooting zone are carried out in rhizoboxes in order to study plant induced heterogeneity in the mycorrhizosphere in terms of acidification/alkalinisation, the occurrence of potentially P mobilizing substances, P mobilization and microbial community composition.

1.在森林土壤发育过程中，磷的丰度和有效性通常下降，从而限制了生物活性。森林生态系统通过发展有效的磷循环机制来适应这一过程，包括形成稳定的磷库和优化树木对磷的吸收。在中欧，这种敏感的演变受到人为沉积导致的土壤酸化加速的干扰。在各种森林中观察到的磷营养的快速下降支持了这一假设。目的本项目研究了挪威云杉和欧洲山毛榉的磷吸收和活化效率是如何沿着土壤生态梯度增加的，从初级矿物中磷的植物有效性高的“年轻”土壤到矿物磷的有效性降低的“老化土壤”。即保持树木的磷可用性，同时最大限度地减少磷浸出，以及ii）如何通过氮（N）施肥或通过实验石灰增强酸缓冲的人工加速酸化将发生变化，或可能干扰磷的吸收和动员效率。我们要评估以下竞争过程i）存储/固定的P在土壤中，ii）P出口与渗漏水和iii）采矿的土壤P资源的树通过根和菌根菌丝与菌根土壤之间的相互作用。这三个过程在天然森林土壤中都表现出明显的空间异质性，我们的目标是在我们的实验中保持这种异质性，以便在生态系统水平上评估它们的相关性。材料和方法将在温室中用来自SPP核心地点的土壤和1至2年生云杉和山毛榉幼苗进行围隔实验：i）在自然结构的土柱中，通过测量土壤中P-物种的组成和分布，土壤水中的P通量，和植物对磷的吸收。单独的治疗和不包括有机表面层的目的是评估有机和无机土壤的磷营养的相对作用。在酸性磷耗竭梯度的两个极端位置，研究了石灰和氮肥的干扰作用。ii）通过比较来自一个酸性位点的B层的自然结构土壤与不同基质势的筛分土壤，研究了矿质土壤团聚体结构和通气性对P吸收和活化效率的影响。iii）在根箱中用来自主要生根区的筛分土壤进行实验，以研究植物诱导的菌根圈在酸化/碱化、潜在P动员物质的发生、P动员和微生物群落组成方面的异质性。