Context Functional responses to landscape heterogeneity are context-dependent, hampering the transferability of landscape-scale conservation initiatives. Japan provides a unique opportunity to test for regional modification of landscape effects due to its broad temperature gradient, coincident with a gradient of historical disturbance intensity. Objectives To quantify and understand how regional contexts modify forest bird community responses to landscape heterogeneity across Japan. Methods We characterised the functional trait composition and diversity of breeding bird communities from 297 forest sites, and applied a cross-scale analytical framework to explain regional variation in community responses. Results The effects of landscape diversity, coincident with forest loss, varied in strength and even direction across the temperature gradient. Cool regions of Japan with highly forested, homogeneous landscapes supported bird communities dominated by forest specialists: those with narrow habitat breadths and insectivorous diets. Warmer regions comprised communities dominated by generalists with wider habitat breadths, even in contiguous, highly forested landscapes. Heterogeneous landscapes selected for generalists, and only promoted functional trait diversity in cool regions where both specialists and generalists can be supplied by a diverse regional pool. Conclusions Our results provide evidence that regional variation in trait responses to landscape heterogeneity—driven by past environmental filtering and broad-scale climates—leads to differential community responses across Japan. Future research that seeks a nuanced understanding of the regional modification of landscape variables will better serve to inform and target real-world conservation efforts.

中文翻译：

---

景观对森林鸟类群落影响的区域变异性

环境对景观异质性的功能响应是依赖于环境的，阻碍了景观尺度保护举措的可转移性。由于其广泛的温度梯度，与历史干扰强度梯度相一致，日本提供了一个独特的机会来测试景观效应的区域变化。目标 量化和了解区域环境如何改变森林鸟类群落对日本各地景观异质性的反应。方法我们表征了来自 297 个森林地点的繁殖鸟类群落的功能性状组成和多样性，并应用跨尺度分析框架来解释群落响应的区域差异。结果 景观多样性的影响与森林丧失同时发生，在温度梯度上的强度和方向各不相同。日本凉爽地区拥有高度森林化、均质的景观，支持以森林专家为主的鸟类群落：栖息地范围狭窄且食虫的鸟类。温暖地区包括由栖息地范围更广的通才主导的社区，即使在连续的、高度森林化的景观中也是如此。为通才选择的异质景观，只在凉爽的地区促进功能特征的多样性，在那里，专家和通才都可以由多样化的区域库提供。结论我们的研究结果提供了证据，表明对景观异质性的特征响应的区域差异 - 由过去的环境过滤和大尺度气候驱动 - 导致日本各地的不同社区响应。