Data from: Breeding bird species diversity across gradients of land use from forest to agriculture in Europe

Loss, fragmentation and decreasing quality of habitats have been proposed as major threats to biodiversity world-wide, but relatively little is known about biodiversity responses to multiple pressures, particularly at very large spatial scales. We evaluated the relative contributions of four landscape variables (habitat cover, diversity, fragmentation and productivity) in determining different components of avian diversity across Europe. We sampled breeding birds in multiple 1-km2 landscapes, from high forest cover to intensive agricultural land, in eight countries during 2001−02. We predicted that the total diversity would peak at intermediate levels of forest cover and fragmentation, and respond positively to increasing habitat diversity and productivity; forest and open-habitat specialists would show threshold conditions along gradients of forest cover and fragmentation, and respond positively to increasing habitat diversity and productivity; resident species would be more strongly impacted by forest cover and fragmentation than migratory species; and generalists and urban species would show weak responses. Measures of total diversity did not peak at intermediate levels of forest cover or fragmentation. Rarefaction-standardized species richness decreased marginally and linearly with increasing forest cover and increased non-linearly with productivity, whereas all measures increased linearly with increasing fragmentation and landscape diversity. Forest and open-habitat specialists responded approximately linearly to forest cover and also weakly to habitat diversity, fragmentation and productivity. Generalists and urban species responded weakly to the landscape variables, but some groups responded non-linearly to productivity and marginally to habitat diversity. Resident species were not consistently more sensitive than migratory species to any of the landscape variables. These findings are relevant to landscapes with relatively long histories of human land-use, and they highlight that habitat loss, fragmentation and habitat-type diversity must all be considered in land-use planning and landscape modeling of avian communities.生境丧失、生境破碎化（habitat fragmentation）与生境质量退化已被认定为全球生物多样性（biodiversity）面临的核心威胁，然而学界对生物多样性应对多重环境压力的响应规律仍缺乏足够认知，在超大空间尺度下更是如此。本研究针对欧洲全域的鸟类多样性各维度，评估了四类景观变量：生境覆盖度（habitat cover）、生境多样性（habitat diversity）、生境破碎化与生境生产力（habitat productivity）的相对贡献量。研究于2001至2002年间，在8个国家的多个1平方千米样地景观中开展繁殖鸟类调查，样地覆盖了从高森林覆盖区域到集约化农田的多种生境类型。我们提出如下研究假设：鸟类总多样性会在森林覆盖度与破碎化程度处于中等水平时达到峰值，并随生境多样性与生产力提升呈正向响应；森林依赖型与开阔生境专性物种会沿森林覆盖度与破碎化梯度呈现阈值响应特征，且随生境多样性与生产力提升呈正向响应；留鸟相较候鸟，会受到森林覆盖度与破碎化更强的影响；广适性物种与城市物种则仅表现出微弱的响应。但研究结果显示，鸟类总多样性并未在中等森林覆盖度或破碎化水平下达到峰值。经稀疏法标准化物种丰富度（rarefaction-standardized species richness）随森林覆盖度提升呈微弱线性下降趋势，随生产力提升呈非线性增长；而所有多样性指标均随生境破碎化程度与景观多样性增加呈线性上升。森林依赖型与开阔生境专性物种对森林覆盖度大致呈线性响应，对生境多样性、破碎化与生产力的响应则较为微弱。广适性物种与城市物种对各类景观变量的响应均较弱，但部分类群对生产力呈非线性响应，对生境多样性的响应则较为微弱。留鸟并未在所有景观变量下均表现出比候鸟更强的敏感性。本研究结果适用于具备较长人类土地利用历史的景观系统，同时强调：在鸟类群落的土地利用规划与景观模拟研究中，必须同时考量生境丧失、生境破碎化与生境类型多样性这三类因素。