Distribution of endemic plant species on an oceanic island – a geospatial analysis of La Palma (Canary Islands)

AbstractPlant species distribution on oceanic islands is primarily determined by environmental limitations. Especially endemic species display a strong dependency on climatic conditions as a consequence of their limited distribution. Under such circumstances, environmental changes may cause not only the extinction of local populations, but of whole species. Thus, climate change can be considered a potential threat to island biodiversity. Research objectives involve identifying the main ecological drivers responsible for species distribution on La Palma and giving an outlook on future perspectives. High resolution GIS data and a presence/absence dataset were used for the analysis. Metric data was correlated using simple regressions. The dataset reflects the spatial and ecological distribution of the potential environmental niches very well. In respect to further research, the island of La Palma can be considered to serve as an ideal system for environmental niche modeling

Bos primigenius in Ancient Egyptian art - historical evidence for the continuity of occurrence and ecology of an extinct key species

Knowledge of the habitat requirements and temporal stability of populations of extinct aurochs (Bos primigenius) is surprisingly scarce. Reliable reports of this species, which by its domestication remains tremendously important for humans, are rare. As the species became extinct about 400 years ago and regionally disappeared much earlier, its behaviour and morphology are also under debate. Aurochs is also a crucial component of the mega-herbivore theory in nature conservation, but in fact its natural habitat and behaviour are unknown. Here, I report records of aurochs for the time period of Ancient Egypt. They are found in archaeological sites and literature, and in collections. Records of the species continue through all the periods of Ancient Egypt. In particular, hunting scenes illustrating the merits of high-ranking persons, in their graves (mastabas) and temples, provide insights into the behaviour and ecology of the depicted game. Here, special attention is given to one outstanding hunting scene that is documented in a relief at the mortuary temple of Ramesses III (1175 BC, Medinet Habu, Egypt). Assisted by a group of hunters, the pharaoh kills three specimens of aurochs. The whole scene is stunningly realistic.  The adult specimen is fleeing towards the reed belt of the River Nile, suggesting that the species’ habitat was probably in large valley bottoms, where open grassland is regularly created by flooding. Endemic species of fish and game confirm that this scene took place in Lower Egypt. The regional populations of the North-African subspecies of aurochs probably went extinct shortly after this piece of art was produced. Records of species in ancient art can be very informative in terms of ecology and behaviour of species, especially when extinct species are addressed. In addition, the dating of old pieces of art containing biological information can be very precise, for instance when these refer to a historic personage.

High Recovery of Saplings after Severe Drought in Temperate Deciduous Forests

Drought episodes are predicted to increase their intensity and frequency globally, which will have a particular impact on forest vitality, productivity, and species distribution. However, the impact of tree species interaction on forest vulnerability to drought is not yet clear. This study aims to assess how deciduous saplings react to drought and whether tree species diversity can buffer the impact of drought stress on tree saplings. Based on field measurements of crown defoliation and species diversity, vulnerability, drought recovery, and species interaction were analyzed. Fieldwork was carried out in Central Eastern Germany in 2018 during the vegetation season and repeated in 2019. Ten random saplings were measured in each of the 218 plots (15 × 15 m) with 2051 saplings in total out of 41 tree species. We found that 65% of the saplings experienced defoliation during the drought of 2018, of which up to 13% showed complete defoliation. At the species level, Fagus sylvatica L. and Betula pendula Roth. saplings were less affected (<55%), whereas Carpinus betulus L., Sorbus aucuparia L., and Frangula alnus Mill. saplings were the most affected (≥85%). One year later, in 2019, C. betulus and S. aucuparia had a faster recovery rate than F. sylvatica, B. pendula, Quercus spp., and Crataegus spp. (p < 0.001). Furthermore, we showed that forest stands with high sapling species diversity had a reduced vitality under drought stress (p < 0.001), indicating a higher competition for resources. The study provides evidence that F. sylvatica saplings can withstand and survive to persistent drought. Species-specific responses to drought are essential to be considered for implementing adaptive forest management strategies to mitigate the impact of climate change

Landscape fragmentation of the Natura 2000 network and its surrounding areas

Habitat loss from anthropogenic development has led to an unprecedented decline in global biodiversity. Protected areas (PAs) exist to counteract this degradation of ecosystems. In the European Union, the Natura 2000 (N2k) network is the basis for continent-wide conservation efforts. N2k is the world’s largest coordinated network of protected areas. However, threats to ecosystems do not stop at the borders of PAs. As measured by a landscape fragmentation metric, anthropogenic development can affect the interiors of PAs. To ensure the long-term viability of the N2k network of PAs, this paper attempts to quantify the degree to which N2k sites are insulated from development pressures. We use a comprehensive dataset of effective mesh density (seff) to measure aggregate fragmentation inside and within a 5 km buffer surrounding N2k sites. Our results show a strong correlation (R² = 0.78) between fragmentation (seff) within and around N2k sites. This result applies to all biogeographical regions in Europe. Only a narrow majority (58.5%) of N2k sites are less fragmented than their surroundings. Remote and mountainous regions in northern Europe, the Alps, parts of Spain, and parts of eastern Europe show the lowest levels of fragmentation. These regions tend to hold the largest N2k sites as measured by area. In contrast, central and western Europe show the highest fragmentation levels within and around N2k sites. 24.5% of all N2k sites are classified as highly to very-highly fragmented. N2k PA age since initial protection does not correlate with the difference in exterior and interior fragmentation of N2k PAs. These results indicate that PAs in Europe are not sheltered from anthropogenic pressures leading to fragmentation. Hence, we argue that there is a high potential for improving PA efficacy by taking pre-emptive action against encroaching anthropogenic fragmentation and by targeting scarce financial resources where fragmentation pressures can be mitigated through enforced construction bans inside PAs