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

Pingree Melissa R, Seattle WA

Investigators

Abstract

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.