Assessing the impact of climate change on the assembly and function of arable plant communities

Diverse plant communities are an important component of the fabric of the countryside. As well as having intrinsic cultural and aesthetic value, they provide the resources that support wildlife. It is likely that global warming will alter the distribution of individual plant species and the composition of communities. For example, increasing temperatures will affect the time plants flower and changing rainfall patterns may increase drought stress in the summer. Climate change may even allow invasive plant species (for example, ones that are currently adapted to a Mediterranean climate) to establish in the UK. One way that has been used to predict how the distribution of species may vary in response to climate change is to determine the climatic range of the areas where a species is currently found now and then to predict how that range may shift. However, this approach is limited and is only useful on a continental scale, because it doesn't take into account all the other factors that might determine whether a plant can survive in a locality such as land management or competition from other plants. For many years, scientists have been studying how plants adapted to cropped fields (weeds) respond to these factors in order to advice farmers how to manage them. This proposal will use the information available on weeds to help develop a general understanding of the impact of climate change on plant communities at a regional scale. We will do this by combining computer models that are able to predict the response of plants to the environment and management with simulations of what the weather might be like in the future. The work will help us to decide what is most important in controlling which plants grow where if the climate changes - is it the weather or the way land is managed? We will also be able to predict whether, for a farm in a given location, the plants that are able to grow in the crops will be broadly similar to now under climate change or if there will be changes. This may have consequences for the way weeds are controlled and the biodiversity they can support.

There is concern about the potential impact of climate change on the diversity of the UK flora and the fauna it supports. It is likely that the increasing temperatures, changing rainfall patterns and increased likelihood of extreme events predicted by Global Climate Models (GCMs) will alter the current distribution of indigenous plant species and may provide opportunities for non-indigenous plants to invade. The conventional approach to predicting these changes has been to combine species distribution models (based on current habitat range) with GCMs to model the shift in the bioclimatic envelope. However, the species assembly that ultimately occupies a locality will also depend on local conditions, land management and biotic interactions. All of these drivers are likely to respond to climate change and, if the resulting shift in plant functional diversity is to be predicted, they all need to be included in the analysis within a simulation framework based on climate change scenarios predicted for a selected region. Because an extensive literature on the eco-physiology of weeds and their response to the environment and management already exists, arable plant communities are an ideal model system for addressing this fundamental research challenge. We will combine a process based eco-physiological model of weed population dynamics and competition with a stochastic weather generator to predict the shift in the realised niche of indigenous UK arable plants and the potential for non-indigenous species to invade on a regional scale. In addition, the ability of species to adapt and the potential shift in plant functional diversity will be predicted using data on intra and inter specific variability in plant functional traits. The approaches and principles developed in the proposal will be instrumental in improving the predictive understanding and manipulation of plant communities in a range of habitats under climate change including grassland systems.