SP05: Soil nutrient dynamics

点击翻译按钮获取中文摘要

With ongoing climate change, the frequency of extreme events is increasing. Extreme events such as floods or droughts affect the availability of water and, thus, inevitably impact nutrient cycling in soils. The majority of grassland studies reported a nutrient flush in soil upon rewetting after drought which is eventually followed by nutrient leaching losses compromising water quality after droughts. The nutrient flush is linked to nutrient dynamics of plants and soil microorganisms and is determined by opposing processes during the drought (= resistance) and after the subsequent rewetting (= recovery).In this context, the objectives of our subproject (SP05) are (i) to assess the resistance and recovery of soil microbial nutrient dynamics during and after a drought, respectively, (ii) to test the effect of plant diversity on the resistance and recovery of microbial nutrient dynamics in soil and link this to other organisms (plants, soil fauna), and (iii) to test the long-term effect of plant diversity on soil nutrient dynamics under extreme events. We hypothesize that the soil microbial community reduces nutrient uptake and is prone to nutrient release during drought but rapidly takes up nutrients after a drought. In other words, microbial nutrient pools in soil quickly recover after drought and furthermore, faster at high as compared to low plant diversity. Particularly at high plant diversity, the nutrient dynamics of soil microorganisms and other organisms are complementary, i.e. temporally asynchronous. Consequently, plant diversity stabilizes nutrient dynamics in spite of frequent extreme events in the long run.To test these hypotheses, our research will be based on the common research platforms (ResCUE Experiment; Main Experiment). Furthermore, we will rely on data of different temporal resolutions to assess nutrient dynamics related to resistance, recovery and stability. We will use state-of-the-art methods (soil microbial nutrient concentrations), stable isotope labeling and natural abundance levels of stable isotopes. Our SP will benefit from synergies arising from cooperation with the other SPs involved in the Research Unit. Overall, SP05 will contribute facets of multifunctional stability to test the central hypothesis that multifunctional stability is highest in high-diversity plots due to a variety of forms of ecological complementarity. Ultimately, stabilizing effects of plant diversity by ecological complementarity are expected to minimize drought-induced nutrient flushes and thus, to maintain tight nutrient cycles. In view of contemporary climate change, plant diversity could mitigate the risk of detrimental effects on water bodies that accompany extreme events.