Seeds in farmland food-webs: Resource importance, distribution and the impacts of farm management

• Published in: Biological conservation 2011-12, Vol.144 (12), p.2941-2950
• Main Authors: Evans, Darren M., Pocock, Michael J.O., Brooks, Joanna, Memmott, Jane
• Format: Article
• Language: English
• Subjects: agricultural land; Agro-ecosystems; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Applied ecology; bioenergy; Biological and medical sciences; biomass; birds; Conservation, protection and management of environment and wildlife; Ecological networks; ecosystem services; energy; energy crops; farm management; farms; food webs; foods; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; Habitat modification; habitats; insect rearing; insects; invertebrates; mammals; organic production; parasitoids; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; pest control; seeds; small fruits; soil; Spatial temporal distributions; summer; weeds; woodlands
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2011.08.013

► We estimate seed and berry animal food resources on a whole farm. ► We examine farm management impacts on seed biomass, energy and a tripartite food-web. ► Animal food resources of up to 33tons of biomass and 560GJ of energy are available. ► Management intensity affects the food-web and can lead to a 19% decline in resources. Whilst considerable research effort in Europe has linked agricultural intensification with dramatic declines of seed-feeding birds, surprisingly little is known about the wider importance of seeds in animal food-webs. Moreover, understanding the dynamics of farmland seed food resources for species of conservation concern is of considerable research interest. We examined the distribution of berries and soil-surface seeds in the managed and unmanaged habitats of a 125ha organic farm. We took soil suction-samples over a year, counted and identified all seeds, and compared abundances and species-richness between habitats. We constructed ecological networks from literature records and by rearing insects to investigate the importance of these seeds for insects, birds and mammals. We predicted the impacts of management on seed biomass, energy and the ecosystem service of pest control across the whole farm. We estimated seed and berry food resources of up to 33metric tons of biomass and 560GJ of energy on the farm. Potentially, more than 330 species use the seeds as a food resource, the overwhelming majority of which are invertebrates (82%) relying predominantly on non-crop and weed species. Generally, uncultivated semi-natural habitats such as woodland and mature hedgerows were more species-rich and had higher seed biomass and energy than crop habitats throughout the year, but fallow land was disproportionately important for seeds during the summer. Models of increased management intensity revealed declines of up to 19% in seed biomass and energy and cascades through the network that resulted in a substantial decrease in potentially pest-controlling parasitoids.