Data from: Low-intensity agricultural landscapes in Transylvania support high butterfly diversity: implications for conservation

European farmland biodiversity is declining due to land use changes towards agricultural intensification or abandonment. Some Eastern European farming systems have sustained traditional forms of use, resulting in high levels of biodiversity. However, global markets and international policies now imply rapid and major changes to these systems. To effectively protect farmland biodiversity, understanding landscape features which underpin species diversity is crucial. Focusing on butterflies, we addressed this question for a cultural-historic landscape in Southern Transylvania, Romania. Following a natural experiment, we randomly selected 120 survey sites in farmland, 60 each in grassland and arable land. We surveyed butterfly species richness and abundance by walking transects with four repeats in summer 2012. We analysed species composition using Detrended Correspondence Analysis. We modelled species richness, richness of functional groups, and abundance of selected species in response to topography, woody vegetation cover and heterogeneity at three spatial scales, using generalised linear mixed effects models. Species composition widely overlapped in grassland and arable land. Composition changed along gradients of heterogeneity at local and context scales, and of woody vegetation cover at context and landscape scales. The effect of local heterogeneity on species richness was positive in arable land, but negative in grassland. Plant species richness, and structural and topographic conditions at multiple scales explained species richness, richness of functional groups and species abundances. Our study revealed high conservation value of both grassland and arable land in low-intensity Eastern European farmland. Besides grassland, also heterogeneous arable land provides important habitat for butterflies. While butterfly diversity in arable land benefits from heterogeneity by small-scale structures, grasslands should be protected from fragmentation to provide sufficiently large areas for butterflies. These findings have important implications for EU agricultural and conservation policy. Most importantly, conservation management needs to consider entire landscapes, and implement appropriate measures at multiple spatial scales.

欧洲农田生物多样性因土地利用向农业集约化或撂荒转型而持续下降。部分东欧农业系统保留了传统利用模式，因此维持了较高的生物多样性水平。然而，当前全球市场与国际政策正推动这些系统发生快速且深刻的变革。若要有效保护农田生物多样性，明确支撑物种多样性的景观特征至关重要。本研究以罗马尼亚南特兰西瓦尼亚的历史人文景观为研究区域，以蝴蝶为研究对象探讨该问题。本研究遵循自然实验设计，在农田中随机选取120个调查样地，其中草地与耕地各60个。于2012年夏季采用样线法开展四次重复调查，记录蝴蝶的物种丰富度与个体丰度。采用去趋势对应分析（Detrended Correspondence Analysis）解析物种组成。采用广义线性混合效应模型（generalised linear mixed effects models），分析三种空间尺度下地形、木本植被覆盖度及生境异质性对物种丰富度、功能群丰富度及选定物种种群丰度的影响。研究结果显示，草地与耕地的蝴蝶物种组成存在广泛重叠。物种组成随局部尺度与背景尺度的生境异质性梯度，以及背景尺度与景观尺度的木本植被覆盖度梯度发生变化。局部生境异质性对物种丰富度的影响在耕地中呈正向效应，而在草地中则呈负向效应。多尺度下的植物物种丰富度、生境结构与地形条件可解释物种丰富度、功能群丰富度及物种种群丰度的变异。本研究证实，低集约化程度的东欧农田中，草地与耕地均具备较高的保护价值。除草地外，异质性耕地同样可为蝴蝶提供关键栖息地。耕地中的蝴蝶多样性得益于小型尺度的生境异质性，而草地则需避免生境破碎化，以维持足够的种群生存面积。上述研究结果对欧盟农业与保护政策具有重要指导意义。最为关键的是，保护管理需统筹整体景观，并在多空间尺度下落实合理的保护措施。