Meta‐analysis plays a crucial role in syntheses of quantitative evidence in ecology and biodiversity conservation. The reliability of estimates in meta‐analyses strongly depends on unbiased sampling of primary studies. Although earlier studies have explored potential biases in ecological meta‐analyses, biases in reported statistical results and associated study characteristics published in different languages have never been tested in environmental sciences. We address this knowledge gap by systematically searching published meta‐analyses and comparing effect‐size estimates between English‐ and Japanese‐language studies included in existing meta‐analyses. Of the 40 published ecological meta‐analysis articles authored by those affiliated to Japanese institutions, we find that three meta‐analysis articles searched for studies in the two languages and involved sufficient numbers of English‐ and Japanese‐language studies, resulting in four eligible meta‐analyses (i.e., four meta‐analyses conducted in the three meta‐analysis articles). In two of the four, effect sizes differ significantly between the English‐ and Japanese‐language studies included in the meta‐analyses, causing considerable changes in overall mean effect sizes and even their direction when Japanese‐language studies are excluded. The observed differences in effect sizes are likely attributable to systematic differences in reported statistical results and associated study characteristics, particularly taxa and ecosystems, between English‐ and Japanese‐language studies. Despite being based on a small sample size, our findings suggest that ignoring non‐English‐language studies may bias outcomes of ecological meta‐analyses, due to systematic differences in study characteristics and effect‐size estimates between English‐ and non‐English languages. We provide a list of actions that meta‐analysts could take in the future to reduce the risk of language bias.

A B S T R A C TFlooded rice fields can provide habitats for wetland species and ecosystem services similar to those of natural wetlands. During the last three decades, however, farming practices and management systems have been intensified in many rice-producing countries. In addition, more recent socioeconomic changes have caused agricultural abandonment in some parts of East and Southeast Asian countries such as Japan. This study reviewed long-term statistics on rice farming, as well as the impact of agricultural intensification and abandonment on farmland biodiversity at multiple spatial scales in Japan. The impact of pesticide use was greatest in the 1950s-1970s, when the use of highly toxic agents had not yet been prohibited. More recently, different components of agricultural intensification have been the largest threat for various taxa, for example, chemical pesticides for aquatic plants and invertebrates and modern efficient irrigation/ drainage systems for amphibians, fishes, and waterbirds. The negative impacts of agricultural abandonment on farmland species have been rapidly increasing with the expansion of abandoned fields and the subsequent vegetation succession and loss of habitat heterogeneity. We also discuss the effectiveness of environmentally friendly farming practices, including the reduced use of pesticides, winter paddy flooding, and installation of fishways, to reduce the negative impacts of agricultural intensification on farmland species in rice-paddy landscapes.

The importance of landscape heterogeneity to biodiversity may depend on the size of the geographic range of species, which in turn can reflect species traits (such as habitat generalization) and the effects of historical and contemporary land covers. We used nationwide bird survey data from Japan, where heterogeneous landscapes predominate, to test the hypothesis that wide-ranging species are positively associated with landscape heterogeneity in terms of species richness and abundance, whereas narrow-ranging species are positively associated with landscape homogeneity in the form of either open or forest habitats. We used simultaneous autoregressive models to explore the effects of climate, evapotranspiration, and landscape heterogeneity on the richness and abundance of breeding land-bird species. The richness of wide-ranging species and the total species richness were highest in heterogeneous landscapes, where many wide-ranging species showed the highest abundance. In contrast, the richness of narrow-ranging species was not highest in heterogeneous landscapes; most of those species were abundant in either open or forest landscapes. Moreover, in open landscapes, narrow-ranging species increased their species richness with decreasing temperature. These results indicate that heterogeneous landscapes are associated with rich bird diversity but that most narrow-ranging species prefer homogeneous landscapes—particularly open habitats in colder regions, where grasslands have historically predominated. There is a need to reassess the generality of the heterogeneity-biodiversity relationship, with attention to the characteristics of species assemblages determined by environments at large spatiotemporal scales.

Farmland abandonment is increasing worldwide. Concurrently, some conservationists view this as an opportunity for biodiversity restoration (i.e., rewilding). Due to a lack of data, however, it remains unclear whether farmland abandonment increases biodiversity in different farmland types and surrounding environments. Information is particularly scarce for Asia, home to one-third of identified biodiversity hotspots and where dominant farmlands (i.e., rice fields) are often viewed as substitutes for natural wetlands. We conducted the first meta-analysis of the impacts of rice-field abandonment on biodiversity, in which we considered multiscale factors, such as taxon surveyed, landscape context, and climate. Species richness and abundance after abandonment decreased to 56-72%. This reduced biodiversity was unlikely to recover, at least for plant species richness, even after 10-15 years. These results suggest rewilding will not necessarily be achieved by rice-field abandonment. Moreover, there was a pronounced biodiversity decline under dry conditions (e.g., low precipitation), especially for organisms closely associated with aquatic environment, such as amphibians and fish. Biodiversity reduction was least pronounced for birds and mammals. Such context dependency may suggest that impacts of farmland abandonment can be predicted by considering biological features of organisms and their associations with human-modified environments.

1. 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.2. 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 2013-2015.3. 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.4. 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 | 1971 Journal of Applied Ecology KATAYAMA eT Al. Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Katayama N, Osada Y, Mashiko M, et al. Organic farming and associated management practices benefit multiple wildlife taxa: A large-scale field study in rice paddy landscapes.