Table7_Biodiversity changes in abandoned military training areas: relationships to different management approaches in multiple taxa.docx

Introduction: Abandoned military training areas are biodiversity strongholds, and this is particularly true for open-habitat and threatened species in Central Europe. Such species benefited from a specific disturbance regime created by military activities that maintained small-grained environmental heterogeneity. However, the disturbance regime no longer occurs after abandonment and the biodiversity is at risk due to forest and shrub encroachment if the areas are left unmanaged. To combat these adverse changes, several management options are used. As these options are not always applied for conservation purposes and substantially differ in their implementation, it is essential to assess their impacts on biodiversity.
Methods: We performed repeated standardized surveys (first in 2009–2010, second in 2020–2022) of vascular plants, grasshoppers, butterflies and birds in 42 abandoned military training areas in Czechia, a Central European country. We calculated changes of species richness and abundance between periods for each taxon and related these changes to six different management types (woody plant cutting, mowing for conservation, mowing for agriculture, grazing for conservation, grazing for agriculture, vehicle movement) performed in these areas between periods.
Results: Vascular plants and grasshoppers showed generally positive changes, whereas the reverse was true for butterflies, and birds experienced mixed changes. Although beta-diversity increased between periods in plants, grasshoppers and butterflies, this increase was driven by extirpation of common species. Management impacts greatly different between respective types and between taxa. Woody plant cutting showed solely positive impacts (on plants and grasshoppers), while the impacts of both types of grazing were mixed (positive on plants and birds, negative on butterflies, mixed on grasshoppers). Mowing for agriculture supported plants and birds but had negative effects on grasshoppers. Mowing for conservation and vehicle movement were linked solely to negative biodiversity changes (former in plants, latter in butterflies).
Discussion: Some components of biodiversity, i.e. plants and grasshoppers, indicate that abandoned military training areas still serve as their strongholds and the management most likely contributes to this favourable state. In contrast, the pattern found for butterflies is worrying since the management performed up to now apparently does not meet their requirements, likely because they are based on smaller-scale habitat mosaic than currently occurs in the areas. Our results may serve as a guide for future prioritization of environmental management, and we urge for development of more nuanced approaches to save the butterflies.

引言：废弃军事训练区是生物多样性庇护所，这一点在中欧的开阔生境物种与受胁物种中尤为凸显。军事活动所形成的特定干扰体系（disturbance regime），维持了细粒度的环境异质性（small-grained environmental heterogeneity）。然而，区域废弃后该干扰体系不复存在，若无人为管理，森林与灌丛入侵将危及区域内的生物多样性。为应对这些不利变化，相关方已采用多种管理方案。由于这些方案并非均以物种保护为核心目标，且实施方式差异显著，评估其对生物多样性的影响便显得至关重要。

方法：我们在中欧国家捷克的42处废弃军事训练区内，针对维管植物（vascular plants）、蝗虫、蝴蝶与鸟类开展了重复标准化调查：首次调查于2009—2010年开展，第二次调查于2020—2022年完成。我们计算了各物种类群在两次调查周期内的物种丰富度与个体丰度变化，并将这些变化与调查周期内区域内实施的6种不同管理类型——木本植物砍伐、保护型刈割、农业型刈割、保护型放牧、农业型放牧、车辆通行——进行关联分析。

结果：维管植物与蝗虫的物种多样性整体呈现正向变化趋势，而蝴蝶则呈现相反的变化模式，鸟类的多样性变化则兼具正反两种特征。尽管植物、蝗虫与蝴蝶的β多样性（beta-diversity）在调查周期内有所提升，但该提升主要由常见物种的局部灭绝所驱动。不同管理类型之间、以及不同物种类群之间的管理影响差异显著。木本植物砍伐仅表现出正向影响（对植物与蝗虫类群），而两种放牧类型的影响则呈混合特征：对植物与鸟类为正向，对蝴蝶为负向，对蝗虫则存在混合变化。农业型刈割对植物与鸟类有利，但会对蝗虫产生负面影响。保护型刈割与车辆通行则仅与生物多样性的负面变化相关：前者影响植物类群，后者影响蝴蝶类群。

讨论：部分生物多样性组分，即维管植物与蝗虫，表明废弃军事训练区仍可作为它们的优质庇护所，而现有管理措施大概率有助于维持这一良好状态。与之形成鲜明对比的是，蝴蝶类群所呈现的变化模式令人担忧——截至目前实施的管理措施显然未能满足它们的生存需求，这可能是因为当前管理方案所依托的生境斑块尺度，小于区域内现有生境的实际分布尺度。本研究结果可为未来环境管理的优先级排序提供科学参考，我们同时呼吁开发更为精细的管理方案以拯救蝴蝶类群。