Journal Article

Organic farming and associated management practices benefit multiple wildlife taxa

Katayama, Naoki, Kusumoto, Yoshinobu, Mashiko, Miyuki, Tanaka, Koichi, Natuhara, Yosihiro, Osada, Yutaka, Baba, Yuki G., Okubo, Satoru, Ikeda, Hiroaki

2019

Overview

Organic farming has potential for the conservation of global biodiversity and associated ecosystem services. Despite this, knowledge of the effects of organic farming systems on farmland biodiversity is limited in Asia, the worldwide leader in rice production. We conducted the first national‐scale study to investigate the effects of three different rice farming systems (conventional, low‐input and organic) and specific management practices (e.g. herbicide and insecticide applications, crop rotation and levee‐vegetation management) on species richness and abundance of multiple taxonomic groups (plants, invertebrates, Pelophylax and Hyla japonica frogs, cobitid loaches and birds) in Japan during 2013–2015. Organic fields supported the highest richness and abundance of several taxonomic groups (native/Red List plants, Tetragnatha spiders, Sympetrum dragonflies and Pelophylax frogs), followed by low‐input and conventional fields. We also found taxon‐specific responses to specific management practices. For instance, plant richness and Tetragnatha and Sympetrum abundance increased with reduced herbicide and/or insecticide applications. Sympetrum and cobitid loach abundance increased in the absence of crop rotation, whereas H. japonica abundance increased with crop rotation. Pelophylax abundance increased with an increased height of levee vegetation. At spatial scales larger than single fields, waterbird richness and abundance were positively correlated with the proportion of organic rice fields, presumably due to increased prey abundance. Meanwhile, landbird richness and abundance were positively associated with annual precipitation and annual mean temperature, suggesting that such climate increases food availability. Synthesis and applications. We highlight the positive effects of organic and low‐input farming for biodiversity relative to conventional farming in rice paddies. We also provide the scientific basis of the current agri‐environmental schemes in Japan, subsidising organic and low‐input farming for biodiversity. The taxon‐specific associations with management practices indicate that avoiding crop rotation, maintaining levee vegetation and organic farming at large spatial scales can also be wildlife friendly. These practices may thus be incorporated into agri‐environment schemes for effective biodiversity conservation. 要旨 有機農業は、生物多様性と、それに関連する生態系サービスの保全に重要な役割を果たすと考えられている。しかし、有機農業が農地の生物多様性にもたらす影響は十分にわかっておらず、特に水稲の主要な生産地であるアジアにおいて知見が非常に少ない。 私たちは、日本の水田では初となる全国規模の野外調査を2013–2015年に行い、慣行、減農薬および有機栽培の3つの農法の違い、および、除草剤・殺虫剤の施用、輪作の有無、畦畔の植生管理等の管理手法の違いが複数の生物種群（植物、無脊椎動物、トノサマガエル属、ニホンアマガエル、ドジョウ科および鳥類）に与える影響を評価した。 在来／レッドリスト植物種数、アシナガグモ属、アカネ属およびトノサマガエル属の個体数は有機栽培の水田で最も多く、次いで減農薬栽培田、慣行栽培田となった。また、管理手法の違いに対する応答は分類群毎に異なることが明らかとなった。具体的には、植物種数、およびアシナガグモ属とアカネ属の個体数は除草剤もしくは殺虫剤施用の少ない水田に多かった。アカネ属とドジョウ科の個体数は輪作を実施しない水田に多かったが、一方でニホンアマガエルの個体数は輪作を実施する水田に多かった。トノサマガエル属の個体数は畦畔の植生高に比例して増加した。 水田団地のスケールでみると、水鳥類の種数・個体数は有機栽培田の面積率と正の相関を示しており、これは食物量の増加によるものと考えられた。一方、陸鳥類の種数・個体数は年降水量および年平均気温と正に相関しており、こうした気候が食物量を増加させる結果と示唆された。 総括および応用　慣行栽培と比較して、有機栽培および減農薬栽培が農地の生物多様性に正の影響をもたらすことが明らかになった。これにより、現在、日本で実施される農業環境政策（有機・減農薬栽培等に対する交付金制度）の効果について科学的な評価基盤を提供することができた。さらに、輪作を回避すること、畦畔植生を適当な高さに維持すること、および有機栽培を行う水田を空間的にまとめることも、特定の分類群の保全に有効であることがわかり、こうした取組の推進が望まれる。 We highlight the positive effects of organic and low‐input farming for biodiversity relative to conventional farming in rice paddies. We also provide the scientific basis of the current agri‐environmental schemes in Japan, subsidising organic and low‐input farming for biodiversity. The taxon‐specific associations with management practices indicate that avoiding crop rotation, maintaining levee vegetation and organic farming at large spatial scales can also be wildlife friendly. These practices may thus be incorporated into agri‐environment schemes for effective biodiversity conservation.

• Publisher: Wiley,Blackwell Publishing Ltd
• Subject: Abundance / agri-environmental policy / agricultural intensification / Agricultural land / Agricultural practices / agri‐environmental scheme / Amphibians / Annual precipitation / Aquatic birds / atmospheric precipitation / Biodiversity / Biodiversity conservation / climate / Cobitidae / Conservation / conventional farming / Crop production / Crop rotation / Dragonflies / Ecosystem services / Farming / Farming systems / farmland biodiversity / Food availability / Frogs / Herbicides / Hyla / Insecticides / Invertebrates / Japan / landscapes / Levees / low input agriculture / low‐input farming / Organic farming / organic foods / organic production / Oryza / paddies / Pelophylax / pesticide application / Prey / RESEARCH ARTICLE / Rice / rice field / Rice fields / Species richness / Spiders / Sympetrum / Taxa / Taxonomy / temperature / Tetragnatha / Vegetation / water birds / Waterfowl / Wildlife / Wildlife conservation / Wildlife management / wildlife‐friendly farming