EAPSI: Ecological Context for Bioavailable Phosphorus in Sub-Boreal Forest Soils of Northern Japan

火是生态系统过程的重要驱动因素，但对其对磷(P)的影响知之甚少，P是植物和动物生命必需的营养物质，在日本北部土壤中有限。土壤微生物和动物，如蚯蚓，在森林生态系统中发挥着重要作用，它们消化有机物，为植物提供磷和其他营养物质，否则植物就无法获得这些营养物质。同时，植物用化学方法改变其直接根区，以提高土壤中磷的有效性和吸收量。土壤磷的常用测量方法不能解释根区获取技术的多样性，而且蚯蚓对土壤磷有效性的改变也知之甚少。这个研究项目将用一种先进的方法来测量日本北部不同土壤类型的土壤磷，这种方法模仿了各种植物磷获取技术。在一个实验室实验中，我们将把土壤与一种常见的蚯蚓物种和野火中的木炭结合起来，以便为可能改变土壤磷有效性的生物活动和森林干扰提供一个背景。该项目将与北海道大学助理教授Kobayashi Makoto博士和副教授Kentaro Takagi博士合作，在日本北海道北部被广泛研究的Teshio实验森林进行。Teshio实验森林是一个理想的实地研究中心，它提供了22,550公顷未受干扰的亚北方森林。日本北部独特的森林代表了从遥远的北方，寒冷的北方森林到温暖的，生物多样性的温带森林的过渡。日本北部亚寒带森林可以为未来的寒带森林提供借鉴。此前在特尾实验林进行的研究为植物-土壤相互作用、养分循环、森林生态和火灾历史提供了有价值的基线。该地区还包含独特的土壤类型汇编，可以外推到不同的地区和环境条件。日本北部蛇纹土和沉积土全磷含量均较低；因此，植物和土壤微生物可能会迅速吸收。Makoto博士进行的研究表明，植物和微生物都采用特殊的机制，在木炭（一种无处不在的野火残留物）存在的情况下获取磷。此外，日本北部森林土壤中蚯蚓的高密度和高活性可能诱发了直接或间接缓解土壤磷限制的过程。通过这次合作，我们将在北海道大学之前的研究基础上，澄清对森林生态系统中植物-土壤和植物-土壤动物相互作用对磷有效性的理解。该奖项隶属于东亚和太平洋暑期研究所项目，由美国国家科学基金会和日本科学促进会共同资助，支持一名美国研究生进行暑期研究。

Fire is an important driver of ecosystem processes yet very little is known about its effects on phosphorus (P), which is an essential nutrient for plant and animal life and limited in northern Japanese soils. Soil microbes and fauna, such as earthworms, provide an essential function in forest ecosystems by digesting organic matter to make P and other nutrients available for plants that otherwise exist in unavailable forms. At the same time, plants chemically alter their immediate root zones to enhance the availability and uptake of P from soils. The common measurement of soil P does not account for the variety of root-zone acquisition techniques and very little is known about earthworm alteration of soil P availability. This research project will measure soil P in contrasting soil types of northern Japan with an advanced method that mimics the variety of plant P acquisition techniques. In a laboratory experiment, we will combine soils with a common earthworm species and charcoal from wildfires in order to provide a context for biological activity and forest disturbance that is likely to alter soil P availability. The project will be conducted in the extensively studied Teshio Experimental Forest located in northern Hokkaido, Japan, in collaboration with Assistant Professor Dr. Kobayashi Makoto and Associate Professor Dr. Kentaro Takagi of Hokkaido University. The Teshio Experimental Forest is an ideal field research center that provides 22,550 hectares of undisturbed sub-boreal forests. The unique forests of northern Japan represent a transition from the far northern, cold boreal forests to warmer, biologically diverse temperate forests. The sub-boreal forests of northern Japan can provide an example for the future forests in the boreal zone. Previous research conducted in the Teshio Experimental Forest provides a valuable baseline for plant-soil interactions, nutrient cycling, forest ecology, and fire history. The area also contains a unique compilation of soil types and that can be extrapolated to different regions and environmental conditions. Total soil P concentrations are low in both serpentine and sedimentary soils of northern Japan; thus, rapid uptake by plants and soil microbes is likely. Research conducted by Dr. Makoto suggests that both plants and microbes employ specialized mechanisms to acquire P in the presence of charcoal, a ubiquitous residue of wildfires. Furthermore, the high earthworm density and activity in northern Japan forest soils may induce processes that have the capacity to directly or indirectly alleviate soil P limitations. With this collaboration, we will build on previous research from Hokkaido University to clarify the understanding of plant-soil and plant-soil fauna interactions in the availability of P in forest ecosystems.This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science.