No abstract

China is one of the most species‐rich countries in the world, harboring many rare gymnosperms. Following recent human‐led loss of forests, China is now experiencing increases in forest cover resulting from efforts of reforestation schemes. As anthropogenic activities have previously been found to interact with topography in shaping forest cover in China and considering the large human population and the ongoing population increase of the country, it is important to understand the role of anthropogenic pressures relative to environmental drivers for shaping species distributions here. Based on the well‐established relationship between human population density and topography, we propose a hypothesis for explaining species distributions in a country dominated by human activities, predicting that species are more likely to occur in areas of steep topography under medium human population densities compared to low and high human population densities. Using species occurrence data from the Chinese Vascular Plant Distribution Database along with a common SDM method (maximum entropy modeling), we tested this hypothesis. Our results show that steep topography has the highest importance for predicting Chinese gymnosperm species occurrences in general, and threatened species specifically, in areas of medium human population densities. Consequently, these species are more often found in areas of steep terrain, supporting the proposed hypothesis. Results from this study highlight the need to include topographically heterogeneous habitats when planning new protected areas for species conservation.

There is increasing focus on reforestation, but the efforts still often include limited subsets of species despite evidence that tree diversity promote biodiversity and ecological resilience. In addition to these benefits, greater inclusion of rare native species in reforestation efforts would also help conserve these species in an uncertain future. Here, we investigate the population ecology and dynamics of the only remaining historical population of the shade-adapted under-and mid-story tree European yew Taxus baccata in Denmark to inform its potential usage in reforestation. The species has been widely extirpated from European landscapes, and while much used in horticulture, is hardly used in reforestation, so there is limited experience with its requirements and performance. We collected data on all individuals in 2015 and compared them with results from a previous census in 1999. Furthermore, we used boosted regression trees (BRT) modelling to investigate the ecological drivers of the distributions of its different life stages. Our results show a stable T. baccata population, with much regeneration in areas of more open-canopy conditions that also support high survival between lifestages. The BRT results show that moss-dominated microhabitats under moderately shaded conditions are important for T. baccata seedling establishment, while higher light availability is important for survival from sapling to adult life-stages. For use in reforestation, we recommend providing moderately shaded microhabitats to allow the seedlings and small saplings to escape competition while also acting as protection from herbivores. Through their long-lived nature, low stature and evergreen foliage, T. baccata would increase the structural complexity of young woodlands, likely enhancing their value for biodiversity, their ecological resilience, as well as their amenity value. Inclusion of T. baccata in reforestation efforts would also aid its spontaneous recolonization of woodland areas, helping it to build larger, more widespread populations with greater resilience to future pressures.