6708 PB Wageningen
Trained as an ecologist I performed my PhD at the NIOO-KNAW but graduated at the Nematology department at the Wageningen University on range-expanding plant species and their belowground interactions with microbes and nematodes. After my graduation I did a postdoc at NIOO-KNAW on grassland restoration and how this changed biogeochemical cycling, soil biodiversity and soil networks in a European project EcoFINDERS. Here I combined field measurements with greenhouse experiments using stable isotope probing to trace the flow of carbon and nitrogen through the members of the soil food web. The ideas sprouted from this postdoc let to a NWO-veni grant which I performed at the University of Amsterdam. Experimentally, the collaboration with NIOO was heavy during this research-fellowship as my experiments were centered around carbon tracing through the soil food web with gut content analyses, root exudates steering soil microbial composition and functioning and soil transplantation experiments for which NIOO-KNAW has excellent facilities. Since 2019 I am a tenure tracker at the University of Amsterdam, but because of my close affinity with the topical research at NIOO-KNAW, I remained a guest researcher at this institute.
Increasing nitrogen (N) deposition severely impacts terrestrial biogeochemical cycles by altering the stoichiometry of ecological components. Although microbes are known to play an important role in biogeochemical cycles, the mechanisms how soil microbes drive nutrient cycling remain elusive under N deposition. Therefore, we investigated changes in microbial community diversity, composition, and interactions, and elucidated the relationship among microbial community responses, soil available nutrients, and ecological stoichiometry resulting from two years of N addition to a Pinus tabuliformis plantation on the Loess Plateau at four rates of N addition (0 (N0), 3.0 (N3), 6.0 (N6), and 9.0 (N9) g N m−2 y−1). N addition significantly influenced microbial composition, decreasing the relative abundance of Acidobacteria and Basidiomycota along N addition gradients and increasing the relative abundance of Ascomycota from N3 to N9. Along N addition gradients except N3, bacterial interactions increased from 62.70% to 73.38%, whereas interactions between bacterial and fungal communities decreased from 34.44% to 24.43%. Among all microbial interactions, the positive ones accounted for a larger proportion (over 55%), indicating a predominance of mutualism under all N addition treatments. Changes in the microbial composition were correlated with soil resource stoichiometry factors, including soil organic carbon: soil total N (SOC:TN) and SOC: soil total phosphorus (SOC:TP), whereas the topological network features were correlated with ammonium N (NH4+-N), nitrate N (NO3−-N), β-1,4-N-acetylglucosaminidase (NAG), alkaline phosphatase (AP), and eco-enzymatic stoichiometry. Therefore, the soil variables that caused changes to microbial composition and interactions were different. In this sense, microbial community compositions were more easily affected by soil resource stoichiometry, whereas microbial interactions were more easily affected by soil available nutrients. In addition, changes to microbial interactions could mediate microbial metabolism via eco-enzyme expression.
Soils are hotspots of diversity and sustain many globally important functions. Here we focus on the most burning issue: how to keep soils as carbon sinks while maintaining their productivity. Evidence shows that life in soils plays a crucial role in improving soil health yet soil ecological processes are often ignored in soil sciences. In this review, we highlight the potential of fungi to increase soil carbon sequestration while maintaining crop yield, functions needed to sustain human population on Earth and at same time keep the Earth livable. We propose management strategies that steer towards more fungal activity but also high functional diversity of fungi which will lead to more stable carbon sources in soil but also affects the structure of the soil food web up to ecosystem level. We list knowledge gaps that limit our ability to steer soil fungal communities such that stabilising carbon in top soils becomes more effective. Using the natural capacity of a biodiverse soil community to sequester carbon delivers double benefit: reduction of atmospheric carbon dioxide by storing photosynthesized carbon in soil and increasing agricultural yields by restoring organic matter content of degraded soils.
Global change frequently disrupts the connections among species, as well as among species and their environment, before the most obvious impacts can be detected. Therefore, we need to develop a unified conceptual framework that allows us to predict early ecological impacts under changing environments. The concept of coupling, defined as the multiple ways in which the biotic and abiotic components of ecosystems are orderly connected across space and/or time, may provide such a framework. Here, we operationally define the coupling of ecosystems based on a combination of correlational matrices and a null modeling approach. Compared with null models, ecosystems can be (1) coupled; (2) decoupled; and (3) anticoupled. Given that more tightly coupled ecosystems displaying higher levels of internal order may be characterized by a more efficient capture, transfer, and storage of energy and matter (i.e., of functioning), understanding the links between coupling and functioning may help us to accelerate the transition to planetary-scale sustainability. This may be achieved by promoting self-organized order.