Evolutionary resistance: Does adaptation stabilise plant community structure and function under climate change?

Globally, we depend on grasslands to support biodiversity and agricultural productivity, offer recreational areas, and provide a wide range of other valuable ecosystem services. For example, the UK dairy industry, which is worth ~£4.27 billion per year, depends entirely on grasslands. At the same time, grasslands are among the most altered and least protected ecosystems, and they are now being to the imminent effects of climate change: warming, drought, flooding.

Grassland organisms may ultimately cope with climate change by adapting, via evolution, where environmental change selects for individuals of a species that have advantageous characteristics (specific 'phenotypes'). This adaptive response stems from both changes in phenotype, and changes in the way organisms express their characteristics in a new environment (called 'phenotypic plasticity). Both aspects increase the likelihood that organisms will thrive in the new environment. Both of these components of evolution can buffer populations against the adverse effects of climate change. However, we do not know how evolutionary change will alter communities of coexisting species or the important ecosystem processes that underpin the important benefits of grasslands to our society.

This study focuses on species-rich grasslands, which have a high conservation value, and are an iconic feature of UK landscapes. They can contain more than 40 plant species per square metre and any of these coexisting species may evolve when exposed to climate change. Nobody knows how these adaptive changes in component species could influence grassland plant communities and the ecosystem as a whole, and whether they will allow grasslands to remain relatively unchanged ("resistant") during climate change. This is because, to date, most scientists have studied climate-driven evolution in single isolated species, which does not allow us to assess how adaptation could influence interactions among co-existing species.

Our research will address this by studying climate-driven evolutionary change in plant communities in a natural grassland. For over two decades, we have exposed a species-rich grassland near Buxton, UK, to simulated climate change (warming, increased rainfall, and drought). Our research has shown very little change in the diversity and abundance of grassland plant species subjected to different climate treatments, meaning that the plant community is resistant to change. However, we have also shown that some of the plant species are adapting to the climate treatments, raising the possibility that evolution itself is the source of resistance to climate change and could explain the stability of the plant community in this species-rich grassland.

Building on our previous work, our overarching goal is to use the Buxton climate experiment as a model to understand how evolutionary changes allow grassland plants to resist climate change at the community and ecosystem levels. In doing so, we aim to determine how species diversity contributes to the services that grasslands provide, and to better understand (and predict) threats to grasslands under climate change.

We have designed a set of experiments to examine how evolutionary adaptation to climate changes in individual plants influences the stability of plant communities and important ecosystem processes. Over three years, we will measure i) the strength and direction of evolution in 16 coexisting plant species, ii) use mathematical modelling to predict climate impacts on grasslands and iii) test for these impacts using targeted experiments at Buxton. This will involve constructing model ecosystems, and measuring species responses, plant phenotypes, and ecosystem processes in the climate treatments. Our research will provide a unique, evolutionary view of how plants, and their phenotypes, contribute to the stability of grasslands and ecosystem processes during climate change.

Our proposed research will provide an integrated view of evolutionary and ecological responses to climate change. Results from this study will reveal how evolution within coexisting plant species can confer stability in grassland structure and ecosystem process rates under climate change. We will gain novel insights into i) the prevalence of evolutionary adaptation within a community of coexisting plants (including effects on plasticity), ii) the importance of evolution for the accurate prediction of species responses to climate change from plant functional traits, and iii) the importance of evolutionary changes in stabilising plant community structure and ecosystem process rates. Our study focuses on calcareous, species-rich grasslands, which support many rare plant species and a rich insect fauna.

Who might benefit from this research? We have identified three key non-academic stakeholder groups:
1. Conservation practitioners, statutory conservation agencies (including Project Partner, Natural England), and other conservation trusts and charities (e.g., the Peak Park Authority, Wildlife Trusts, RSPB, the National Trust) and UK policy-makers such as the Department of Energy and Climate Change, Department of Environment, Food and Rural Affairs.
2. Horticultural businesses and others involved in the production and sale of native seed. This market (£3-6 million value in 2011) is dominated by the production and sale of grassland wildflower mixes and is expected to grow strongly, likely doubling by 2020.
3. The general public, who demonstrate a keen awareness of climate change issues and conservation of species-rich UK habitats.

How might they benefit from this research?
1: Practitioners and policy-makers will benefit through an improved understanding of how adaptive genetic variation contributes to ecosystem resilience during climate change. Our results will provide an evidence base to support policy decisions to optimise landscape management strategies and anticipate threats to grasslands and ecosystem services. Our research will also facilitate the modelling of both the current and the future capacity of grassland landscape to resist climate change by incorporating the effects of evolution. By engaging these organisations in knowledge exchange throughout the programme of research, we will ensure that our work can create impacts with real-world value.
2: Horticultural businesses that supply native seed and seed mixes for habitat restoration could benefit from our project through an improved understanding of climatic impacts on seed restoration success. Our results have the potential to provide the knowledge-base for determining optimal approaches to seed sourcing and choosing species mixtures for wildflower mixes, providing businesses with increased capacity to develop marketable stress-resistant seed mixtures.
3: The general public stand to gain educational and environmental knowledge benefits from our project, through (i) enhanced awareness of potential climatic impacts on biodiversity and the ecological supply chain that provides ecosystem services, and (ii) an improved understanding of the potential for genetic resilience within natural populations and ecosystems. Public engagement through a variety of media will provide many opportunities to promote the research, increase public interest in climate change adaptation, and enhance educational activities to promote field-based learning, ultimately creating a legacy that will outlast the project.
All of the stakeholders are likely to derive long-term benefits from our maintenance of the long-term climate treatments at Buxton. It is difficult to predict the precise nature of these future impacts, but we expect them to accrue through continuing gains in our understanding of grassland ecosystems and their value to man.