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力，但人们对磷(P)的影响知之甚少。磷是动植物生命所必需的营养物质，在日本北部的土壤中有限。土壤微生物和动物，如蚯蚓，通过消化有机物质使磷和其他营养物质可供植物使用，从而在森林生态系统中发挥重要作用，否则植物就无法获得这些养分。同时，植物在化学上改变其直接根区，以提高土壤中磷的有效性和吸收。常用的土壤磷测量方法没有考虑到根区获取技术的多样性，对蚯蚓对土壤磷有效性的影响知之甚少。这项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，这种方法模仿了植物获取磷的各种技术。在实验室实验中，我们将把土壤与一种常见的蚯蚓物种和来自野火的木炭结合起来，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背景。该项目将在日本北海道北部被广泛研究的Teshio实验森林中进行，与北海道大学的助理教授小林博士和副教授Kentaro Takagi博士合作。Teshio实验森林是一个理想的野外研究中心，提供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着从遥远的北方寒冷的北方森林向更温暖的、生物多样性的温带森林的过渡。日本北部的亚北方森林可以为北方地区未来的森林提供范例。之前在Teshio实验森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宝贵的基线。该地区还包含独特的土壤类型汇编，可以根据不同的地区和环境条件进行推断。在日本北部的蛇纹石和沉积土壤中，土壤总磷浓度都很低；因此，植物和土壤微生物可能会迅速吸收磷。Makoto博士进行的研究表明，植物和微生物都使用专门的机制，在木炭存在的情况下获取磷。木炭是野火的一种普遍存在的残留物。此外，日本北部森林土壤的高蚯蚓密度和活动可能会诱导具有直接或间接缓解土壤磷限制的能力的过程。通过这项合作，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磷有效性的植物-土壤和植物-土壤动物相互作用的理解。东亚和太平洋夏季学院计划下的这个奖项支持一名美国研究生的夏季研究，由NSF和日本科学促进会共同资助。

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.