Key challenges and priorities for modelling European grasslands under climate change

Highlights

• Experts identified challenges for European grassland modelling under climate change.

• Fifteen key challenges and associated research priorities were identified.

• Challenges related to specific climate change impacts, adaptation and methodology

• Across challenges, shared resources for stakeholders and researchers were priorities.

Abstract

Grassland-based ruminant production systems are integral to sustainable food production in Europe, converting plant materials indigestible to humans into nutritious food, while providing a range of environmental and cultural benefits. Climate change poses significant challenges for such systems, their productivity and the wider benefits they supply. In this context, grassland models have an important role in predicting and understanding the impacts of climate change on grassland systems, and assessing the efficacy of potential adaptation and mitigation strategies. In order to identify the key challenges for European grassland modelling under climate change, modellers and researchers from across Europe were consulted via workshop and questionnaire. Participants identified fifteen challenges and considered the current state of modelling and priorities for future research in relation to each. A review of literature was undertaken to corroborate and enrich the information provided during the horizon scanning activities. Challenges were in four categories relating to: 1) the direct and indirect effects of climate change on the sward 2) climate change effects on grassland systems outputs 3) mediation of climate change impacts by site, system and management and 4) cross-cutting methodological issues. While research priorities differed between challenges, an underlying theme was the need for accessible, shared inventories of models, approaches and data, as a resource for stakeholders and to stimulate new research. Developing grassland models to effectively support efforts to tackle climate change impacts, while increasing productivity and enhancing ecosystem services, will require engagement with stakeholders and policy-makers, as well as modellers and experimental researchers across many disciplines. The challenges and priorities identified are intended to be a resource 1) for grassland modellers and experimental researchers, to stimulate the development of new research directions and collaborative opportunities, and 2) for policy-makers involved in shaping the research agenda for European grassland modelling under climate change.

Introduction

The agricultural sector is facing unprecedented challenges as it attempts to maintain food security in the context of climate and socio-economic change (Soussana, 2014, Thornton, 2010). The forecasted increase of world population, dietary changes towards increasing meat consumption and the demand for bioenergy suggest a global requirement for agricultural products by 2050 roughly twice that of today (Foley et al., 2011). At the same time as increasing production, the livestock sector will need to improve efficiency (Thornton, 2010) to avoid increasing the 26% of global land area currently used for livestock production, and to reduce its estimated 15% share of total anthropogenic greenhouse gas (GHG) emissions (Ripple et al., 2014). Havlík et al. (2014) suggest that transitions from grass-based to more intensive livestock production systems may represent a cost-effective approach to mitigating GHG emissions from livestock agriculture. However, while grass-based ruminant production systems may be less efficient in terms of GHG emissions and land use than more intensive systems, they provide a range of other benefits; European grasslands store an estimated 5.5 Gt of carbon in the top 30 cm of their soils (Lugato et al., 2014). Covering around 30% of agricultural land in Europe (Huyghe et al., 2014), grasslands also play an important role in the maintenance of biodiversity and the sustenance of rural communities and cultures (Soussana and Lemaire, 2014). Intensification or conversion of grasslands to crop production can lead to the reduction or loss of such benefits (Dusseux et al., 2015). At the same time, ruminants valorise marginal production areas, converting plant materials indigestible to humans into meat and dairy products with high efficiency in terms of the consumption of human-edible food per unit of product (Wheeler and Reynolds, 2013, Wilkinson, 2011). In Europe, around 25% of livestock protein intake comes from grasslands (Leip et al., 2011). Despite these benefits, grasslands have declined in Europe, with an estimated loss of seven million hectares between 1967 and 2007 (Huyghe et al., 2014). Recent predictions suggest that this decline may continue in a climate change future (Leclère et al., 2013). In this context, a better understanding is required of the impacts of climate change on European grassland systems, the efficacy of adaptation strategies to increase their resilience and productivity, and the pathways available to maintain and enhance the essential ecosystem services they provide (Scollan et al., 2010, Smith et al., 2013).

In light of the challenges described, modelling can offer valuable support to farm and policy level decision-makers, by providing tools to explore the performance of biophysical, management and policy systems in the context of future climatic and socio-economic scenarios (Graux et al., 2013, Kipling et al., 2014). A number of high-level strategic assessments of agricultural research priorities (ATF, 2013, ATF, 2014, FACCE-JPI, 2012, Soussana, 2014) present a range of challenges to the agricultural modelling community (Kipling et al., in press). The aim of this paper is to lay out in detail the specific challenges and research priorities that grassland modelling must address, if it is to fulfil its potential role in helping to tackle the global problems faced by the livestock production sector. The focus of the paper is on European grasslands, and covers both permanent grasslands and leys (grasslands established for less than five years). Three broad types of model applied to European grasslands have previously been identified (Bellocchi et al., 2013); specialised grassland models, crop models with grassland options, and vegetation models that can characterise a range of plant communities including grasslands. This paper incorporates challenges relevant for all of these model types, and explores links to other modelling disciplines and approaches.