QuESSA - the benefits of nature
Blow fly larvae sentinel with cage to exclude rodents. © John Holland/GWCT
BACKGROUND
European farming landscapes contain various types of semi- natural habitats (hedgerows, woodland and flower-rich grassland) and these can benefit farming by supporting benefi- cial invertebrates that pollinate crops or contribute to natural pest control leading to improved crop yields. They may also prevent soil erosion, store soil carbon and define landscapes that make them more attractive than crop monocultures. These are all classified as ecosystem services and have become the focus for much research in the last decade. Farmers can obtain funding through Agri-environment Schemes (AES) or as Ecological Focus Areas (EFAs) for the estab- lishment or management of many habitat types, predominantly to encourage biodiversity and preserve historic landscapes, yet the value they provide for farming is relatively unknown.
In 2013 we started work on a four-year project called QuESSA (Quantification of Ecological Services for Sustainable Agriculture), funded by the European Union, with the remit to quantify the contribution of semi-natural habitats (SNH) to ecosystem services, but especially pest control and pollination for a range of crops and farming systems. Working with our 13 partners we developed a range of common methodologies and used these simultaneously in 16 case studies in eight European countries (England, the Netherlands, Estonia, Germany, Hungary, Switzerland, Italy and France) that included seven crops (wheat, oilseed rape, sunflowers, pumpkins, pears, olives and vines).
Overall approach We first identified the key SNH in each country and assessed the vegetation structure and composition, along with the beneficial invertebrates in these habitats. From this we calculated a predictive score for each habitat for pollinators and pest control. Next we measured the actual levels of ecosystem services in our case studies in Hampshire and Dorset, each of which comprised 18 landscape sectors of 314 hectares (ha) of arable farmland centred around a focal field in which the studies were conducted. The landscape sectors were selected to ensure that the proportion of SNH varied from low to high for the region. The focal fields were selected so that they were adjacent to one of three types of SNH, with six replicate fields of each. In the UK the SNH studied were herbaceous linear strips, woody areas such as hedgerows and woodland while grass-only strips served as controls. In most case studies, we measured levels of pollination and pest control, alongside other ecosystem services including soil erosion, soil carbon storage and aesthetic value of the landscape. In the UK we focused on pollination of oilseed rape, pest control in wheat, carbon storage and aesthetics. The data were analysed using standard statistical methods and by approaches developed at Wägeningen University that took into account the type, proportion and distance of each SNH from the focal field. In this way we could identify not only the most important SNH, but the range over which they can have an impact. This approach was also used by the European Commission’s Joint Research Centre in Ispra, Italy along with existing landscape-scale data to generate maps for the whole of Europe that predicted the abundance of pollinators and likely levels of pest control. A selection of our findings for the UK are presented here.
Pollination Oilseed rape is both wind- and insect-pollinated but if pollinators are not sufficiently abundant there may be a pollination deficit and a subsequent yield loss. We measured this by comparing the weight of seed produced for flowers with natural levels of insect visitation to those in which seed set was maximised by additional hand pollina- tion. This was conducted in each focal field and along single transects extending up to 70 metres from the SNH. In two of the six countries testing this (two of which
58 | GAME & WILDLIFE REVIEW 2016
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