Supervisors: John Cussans (Rothamsted Research), Frank van den Bosch (Rothamsted Research), Ken Norris
SUMMARY
Over the last 40 years farmland bird populations have experienced dramatic declines in abundance and reversing these trends is a key conservation objective in the UK. Many of these species are granivorous (seed-eating) during the non-breeding season, and it is now widely accepted that declines in food resources (including weed seeds) due to various management changes in arable farming have contributed to the population declines. Meeting conservation targets requires, therefore, management changes that provide both food resources in arable landscapes for birds and that meet the weed control needs of farmers. Our proposed studentship project aims to develop the ecological models required to design appropriate management, and thereby contribute to the development of more sustainable arable farming systems. To do this, we propose a novel approach that involves developing and integrating existing mechanistic models of weed and bird populations that would allow us to explore trophic interactions between arable plants and birds, and examine their consequences. This work will have important implications for addressing issues of scale in ecology, as well as being of practical importance for management policy and decision-making concerning arable farming systems.
AIMS AND OBJECTIVES
The overall aim of our project is to develop a framework to predict the implications of changing weed and crop management within fields on arable plant and bird populations at a landscape scale. To do this, we will:
- Develop existing arable weed population models to incorporate spatial and temporal stochasticity in population dynamics.
- Develop an existing mechanistic model of seed-eating bird populations to incorporate a wider range of processes important in competition for food e.g. interference.
- Integrate the plant and seed-eating bird models within a landscape model that describes field-scale management.
- Use the integrated model to explore how the spatial and temporal scaling of field-scale management and key ecological processes affects weed population dynamics and bird distribution, mortality and abundance.
- Apply the integrated model to investigate issues relating to agri-environment management.
The end of the last century witnessed a dramatic increase in agricultural intensification that resulted in widespread declines in farmland biodiversity, including birds. Recognition of these wider impacts has led to calls for farming to become more sustainable, moving away from primarily maximizing production to a situation in which farming is considered within a broader framework that includes issues such as animal welfare, human health and the wider environment. Our project proposal falls within this framework in that it is attempting to link field-scale arable management to bird populations via trophic interactions with plant (seed) populations by building on previous work being conducted at Rothamsted and Reading.
Current DEFRA funded work at Rothamsted is focusing on improving our ability to predict the impact of crop management on weed fecundity in the short-term and the dynamics of both species and communities of plants through crop rotations. Model frameworks have been developed to predict the impact of cropping, herbicide and cultivation strategies on a wide range of arable plant species. Previous work at Reading has been aimed at understanding mechanistically how seed-eating birds interact with each other and their food resources (crop and weed seeds) in order to explore population-level consequences (demography, abundance). The work has been used to develop a model that is now being used to examine how management changes at the field-scale within arable landscapes might impact on bird populations at the landscape level, using ecological theory.
Our project will bring these two modelling approaches together in order to build links between field-scale management, plant populations/communities and bird populations. Our aim is to produce a model of an arable landscape that provides a predictive framework for exploring how management at field-scales impacts on plant and dependent bird populations at landscape scales. To do this we will develop and integrate our existing models to incorporate spatial and temporal heterogeneity in plant populations and different mechanisms of competitive interactions between foraging birds. We will then be able to explore how spatial and temporal scaling of management at the field-scale interacts with the scaling of key ecological processes acting in plant populations/communities and seed-eating birds at larger scales (e.g. farm or landscape). Heterogeneity in agricultural landscapes is crucially important for biodiversity, but is rarely examined at farm and landscape scales within the context of agri-environmental management. Our project will provide the ecological tools required to do this. To explore the importance of scale within this context we will develop the landscape model to examine two applied problems. First, we will link in-field management and margin management to ask whether margin management is potentially capable of delivering the kind of changes needed to reverse the degradation in food supplies seen within fields, and explore how this might be affected by scale. Secondly, we will explore how the impact of existing management within fields might be modified, particularly by the timing of farming operations, to reduce its impact on seed-eating bird populations.
The study is funded by ...
