2025-07-04 オックスフォード大学
Trees and hedges on farmland significantly boost butterfly numbers, study finds. Credit: Andrew Cooper.
オックスフォード大学とButterfly Conservation、Woodland Trustの研究により、農地にある生垣や孤立樹、小規模林が蝶の個体数を大幅に増加させることが判明した。イングランドの1,154地点における10年間の蝶の観察データと環境情報を分析し、特にアワノメイガやゲートキーパーなどで顕著な効果が見られた。一方、集中的に管理された草地では蝶の数が少なかった。農家の調査では、生垣の維持にコストがかかるとの声があり、研究者は支援の必要性を訴えている。
＜関連情報＞
- https://www.ox.ac.uk/news/2025-07-04-trees-and-hedges-farmland-significantly-boost-butterfly-numbers-study-finds
- https://besjournals.onlinelibrary.wiley.com/doi/10.1002/2688-8319.70042
農地における生物多様性を促進するための林外の樹木の価値の定量化 Quantifying the value of trees outside woods for promoting biodiversity on farmland
Ruth E. Feber, Paul J. Johnson, Nigel A. D. Bourn
Ecological Solutions and Evidence Published: 03 July 2025
DOI:https://doi.org/10.1002/2688-8319.70042
Abstract
- Within the farmed landscape, trees outside woods (TOWs), such as hedgerows, copses and scattered trees, provide a variety of benefits for wildlife and people, but these are not well understood or recognised. Many TOWs continue to be lost from the landscape.
- We used butterflies as a model group and explored patterns in their abundance and species richness in relation to the extent and type of TOWs, using data from the UK’s Wider Countryside Butterfly Survey. We explored farmers’ views of TOWs using an online survey.
- In general, the predictive power of the statistical models was not high, but some clear patterns emerged. Small woodlands were positively associated with overall butterfly abundance and species richness, especially in more arable landscapes. Higher numbers of ancient trees were associated with higher butterfly species richness. Hedgerows and woody strips had a positive effect on five of seven common species studied. As woodland increased in the landscape, up to a certain level, so did the abundance of meadow brown Maniola jurtina, speckled wood Parare aegeria, ringlet Aphantopus hyperantus and comma Polygonia c-album. More ancient woodland in the landscape was associated with more P. aegeria and A. hyperantus butterflies.
- Farmers viewed TOWs as having a range of benefits, including value for wildlife and the landscape, helping combat climate change, improving soil health and reducing flooding. Time, expense and long-term commitment dominated farmer concerns around TOWs. Management knowledge and practice tended to be more consistent for hedgerows than for other types of TOWs. Most respondents indicated they would like more information on managing TOWs.
- Practical implication. Heterogeneous farmed landscapes rich in hedgerows, small woodlands and ancient trees were associated with more abundant and species-rich butterfly communities than landscapes with few of these features. There was clear recognition by farmers of the benefits of TOWs for farming and the environment. Farmers should be better supported to help deliver these benefits, financially and through knowledge exchange. The protection and restoration of TOWs on farmland should be an essential part of efforts to address the biodiversity and climate crises and at the forefront of farm-scale and landscape-scale initiatives.
