Assessing Conservation Action for Substitution of Missing Dynamics on Former Military Training Areas in Central Europe

Disproportionately large numbers of threatened and endangered species and unusually high biodiversity have been documented on former military training areas. However, throughout the world, nature protection areas on former military grounds are faced with the dilemma of preserving ecosystems that must change. In central Europe, many of these areas are characterized by dry acidic grasslands on sandy soils. However, these resource-limited ecosystems are faced with two interacting threats: missing disturbance dynamics and increasing atmospheric nitrogen deposition from urban agglomerations. The goal of this study was to assess the effectiveness of conservation action for substitution of missing dynamics. Impacts on plant species assembly, performance of functional groups, soil nutrient availability, and successional trajectory are analyzed. Of particular concern is mimicking beneficial effects of military maneuver on pioneer species such as Corynephorus canescens , which is endangered in many countries. In a controlled field experiment, we manipulated mechanical disturbances representing conservation measures—harrowing, topsoil removal, tilling, and tank driving. Our findings suggest that only topsoil removal and tank driving effectively remove organic material and create self-sustaining vegetation dynamics. Topsoil removal affects both filters in community assembly: the abiotic filter related to soil resources and the biotic filter related to competition between species. We further demonstrate that plant functional groups based on growth form show different rates of recruitment after disturbance with graminoids-dominating initial dynamics. This study provides basic information on effective conservation strategies for dry acidic grasslands on former military training areas.