Coupling experimental data with individual‐based modelling reveals differential effects of root herbivory on grassland plant co‐existence along a resource gradient. (19th November 2015)

• Record Type: Journal Article
• Authors: Pfestorf, Hans; Körner, Katrin; Sonnemann, Ilja; Wurst, Susanne; Jeltsch, Florian
• Is Part Of: Journal of vegetation science. Volume 27:Number 2(2016:Mar.)
• Page Start: 269
• Page End: 282
• Publication Date: 2015-11-19
• Subjects: Above‐/below‐ground interactions -- Below‐ground resources -- Competitive hierarchies -- Grassland -- Greenhouse experiment -- Simulation experiment -- Species co‐existence -- Wireworms; Plant ecology -- Periodicals; Plant communities -- Periodicals; Plant populations -- Periodicals; 581.7
• DOI: 10.1111/jvs.12357
• Languages: English
• ISSNs: 1100-9233

Abstract

Abstract: Question: The empirical evidence of root herbivory effects on plant community composition and co‐existence is contradictory. This originates from difficulties connected to below‐ground research and confinement of experimental studies to a small range of environmental conditions. Here we suggest coupling experimental data with an individual‐based model to overcome the limitations inherent in either approach. To demonstrate this, we investigated the consequences of root herbivory, as experimentally observed on individual plants, on plant competition and co‐existence in a population and community context under different root herbivory intensities (RHI), fluctuating and constant root herbivore activity and grazing along a resource gradient. Location: Berlin, Germany, glasshouse; Potsdam, Germany, high performance cluster computer. Methods: The well‐established community model IBC‐Grass was adapted to allow for a flexible species parameterization and to include annual species. Experimentally observed root herbivory effects on performance of eight common grassland plant species were incorporated into the model by altering plant growth rates. We then determined root herbivore effects on plant populations, competitive hierarchy and consequences for co‐existence and community diversity. Results: Root herbivory reduced individual biomass, but temporal fluctuation allowed for compensation of herbivore effects. Reducing resource availability strongly shifted competitive hierarchies, with, however, more similar hierarchies along the gradient under root herbivory, pointing to reduced ecological species differences. Consequently, negative effects on co‐existence and diversity prevailed, with the exception of a few positive effects on co‐existence of selected species pairs. Temporal fluctuation alleviated but did not remove negative root herbivore effects, despite of the stronger influence of intra‐ compared to interspecific competition. Grazing in general augmented co‐existence. Most interestingly, grazing interacted with RHI and resource availability by promoting positive effects of root herbivory. Conclusions: Through integrating experimental data on the scale of individual plants with a simulation model we verified that root herbivory could affect plant competition with consequences for species co‐existence. Our approach demonstrates the benefit that accrues when empirical and modelling approaches are brought more closely together, and that gathering data on distinct processes and under specific conditions, combined with appropriate models, can be used to answer challenging research questions in a more general way. Abstract : Our study combines empirical work and simulation experiments to predict community level consequences of root herbivore feeding observed for individual plants. We establish a competitive hierarchy of the investigated species and show that mainly negative effects of root herbivory on coexistence result from reduced ecological species differences and a stronger interaction of root herbivory with inter‐ than with intra‐specific competition.