Functional-structural modelling as a potential tool to assess the impact of resource competition on arable communities

Sustainable farming systems that maintain the diversity of arable plant communities and associated invertebrates are a key objective for European agriculture. Plant structure-function analysis and modelling are potentially important tools for studying these arable communities, and for understanding the impact of crop-weed interactions on crop productivity and on diversity in arable food webs. To understand the role of plant structure in trophic interactions and community composition, we need knowledge of the 'rules' governing plant structure, and how variation in structure affects the way that plants compete for and acquire resources, both above- and belowground. As a first step to a structural-modelling approach, we have used a sonic digitizer to capture basic information on aboveground plant architecture for several weed species common to UK arable systems. The structural patterns that occurred in plants grown without resource limitation are presented and analysed for Chenopodium album, Polygonum aviculare and Tripleurospermum inodorum. For each species, the importance of these architectural rules for plant response to resource competition is inferred from plant growth habit in the field. The plant structural data gathered here will be used to construct models to explore the interaction between plant architecture and environmental variables, including the impact of resource availability (e.g., due to light competition) on growth and resource partitioning. This study is the initial stage of future work to model the interactions between adjacent plants of differing architectures and resource utilization strategies. The utility of a structure-function approach to observe the evolution of communities of interacting plants under different levels of resource competition is discussed.