Farmland abandonment can be a significant driver of biodiversity change in many parts of the world. Knowledge of the ecological impact of farmland abandonment at the landscape scale is particularly limited in Asia. We investigated how rice-field abandonment impacts bird diversity (i.e., species richness and composition) during the breeding and wintering seasons. Birds were surveyed in 31 grids (1 × 1 km) in rice ecosystems in central Japan, 16 of which were dominated by farmland while the others were surrounded by woodland. In each landscape type, survey grids were selected to ensure a broad range of abandonment rates, from fully cultivated to largely abandoned sites. Multi-species occupancy models showed that occupancy probabilities were associated with linear and quadratic terms of the abandonment rate, resulting in the highest predicted community-level occupancies and species richness at moderate abandonment rates (51.5–71%, depending on the season and surrounding landscapes, with the highest percentage in woodland landscapes in winter). Community composition was most associated with surrounding landscapes (i.e., woodland or farmland), followed by the abandonment rate. These results indicate the importance of habitat heterogeneity, related to moderate levels of farmland abandonment, in enhancing bird diversity in both farmland and woodland landscapes. Our findings illustrate the necessity for quantitative measures of farmland abandonment at landscape scales for understanding their nonlinear effects on farmland biodiversity. We suggest that agri-environmental schemes should consider the benefits of enhancing farmland mosaics at landscape scales, especially for small-scale farming in areas where farmland abandonment is increasing.

在世界许多地方，农田遗弃可能是生物多样性变化的重要驱动因素。在景观尺度上，关于农田废弃对生态影响的知识在亚洲尤其有限。我们调查了稻田遗弃如何在繁殖和越冬季节影响鸟类多样性（即物种丰富度和组成）。在日本中部的水稻生态系统中，在 31 个网格（1×1 公里）中对鸟类进行了调查，其中 16 个以农田为主，而其他则为林地。在每种景观类型中，都选择了调查网格，以确保广泛的废弃率，从完全种植到大部分废弃的地点。多物种占用模型表明，占用概率与放弃率的线性和二次项相关，导致最高预测的社区级占有率和物种丰富度，废弃率适中（51.5-71%，取决于季节和周围景观，冬季林地景观的百分比最高）。群落组成与周围景观（即林地或农田）最相关，其次是废弃率。这些结果表明栖息地异质性与中等程度的农田废弃有关，在增强农田和林地景观中的鸟类多样性方面的重要性。我们的研究结果说明了在景观尺度上定量测量农田放弃的必要性，以了解它们对农田生物多样性的非线性影响。我们建议农业环境计划应考虑在景观尺度上增强农田马赛克的好处，