My main research interest is on how interactions between belowground and aboveground species influence community dynamics and ecosystem processes.
I apply this so-called aboveground-belowground interactions approach to a number of ecological concepts, such as succession and land use change, invasions, climate change-induced range shifts, biodiversity-ecosystem functioning, and land use intensification in a bio-based economy. My key aim is to unravel the contribution of aboveground-belowground biotic interactions relative to other drivers of community change. I use these insights in order to determine consequences of (human-induced) environmental changes for ecosystem functioning and the sustainable provisioning of ecosystem services.
Primary and secondary succession, and land use change
Aboveground-belowground interactions can influence the rate and course of primary and secondary succession. These factors work in addition to abiotic factors, such as soil moisture, pH, organic matter, etc. Both aboveground and belowground biotic interactions may enhance or slow down the rate of succession and these influences can differ along successional gradients. Currently, in secondary succession chronosequences we study interactions between soil food web development, plant, and aboveground community development. These studies are performed in combination with EU-projects, such as the work of Elly Morriën in EcoFinders, and Sanne de Smet in the Wageningen University Systems Biology Program.
Biodiversity and ecosystem functioning
Recent work has shown that the classic positive relationship between plant biodiversity and productivity can be due to soil-borne pathogens that have disproportionate negative effects on plant species in monocultures or in low-diverse plant species mixtures. In the Jena experiment, Roeland Cortois studies plant-soil feedback interactions and soil microbial community dynamics in relation to plant species and trait diversity.
Enemy release is one of the key explanations for the invasiveness of exotic species in their new habitats. There is increased awareness that release from specialized soil-borne pathogens could make plants invasive in the new range. We study enemy release from soil-borne pathogens using various model systems and we have a number of active collaborations. We have studied how soil-borne pathogens may contribute to disproportional abundance in the new range using Ammophila arenaria (marram grass) that has been introduced in coastal foredunes of the USA, South Africa, Australia and New Zealand. Other systems that we work on are Prunus serotina (black cherry) in the USA with Keith Clay and Kurt Reinhart, and a Marsden project on invasive leguminous species in New Zealand with Richard Duncan, Phil Hulme, Tasha Shelby and Kevin McGinn.
Climate change/induced range shifts
Climate warming may disrupt aboveground-belowground multitrophic interactions in a variety of ways. We study consequences of climate warming-induced range shifts on dis-assemblage and re-assemblage of multitrophic communities of plants, soil and aboveground biota. In a recent review in Annual Review of Ecology, Evolution and Systematics the framework for this research has been outlined. Other studies in this area are on effects of long distance dispersal for evolution of plant traits under climate warming, with Katrin Meyer and Janina Radny from Göttingen University and on the role of epigenetics during deglaciation with Koen Verhoeven and Veronica Preite.
In the BE-Basic project, Maarten Schrama studies how the production of bioenergy crops may influence soil biodiversity, ecosystem services, and Sabrina Carvalho examines how this may be detected in an early stage by analyzing hyperspectral reflectance patterns of the crops. In a previous study by Sabrina Carvalho in cooperation with Andrew Skidmore from ITC, Enschede, we have tested how plant exposure to soil-borne pathogens may change light reflectance by the plant canopy. In the BE-Basic project, we will use this approach to detect if plants are placed under stressed soil biotic conditions.