Browsing by Subject "Conservation"

Now showing 1 - 2 of 2

Impact of rubber tree dominated land-use on biodiversity and ecosystem services in the Greater Mekong Subregion
(2017) Häuser, Inga; Sauerborn, Joachim
The present dissertation analyzes the impact of rubber tree (Hevea brasiliensis) dominated land-use on biodiversity and ecosystem services (ESS) in the Greater Mekong Subregion (GMS). Although originating from South-America natural rubber is mainly cultivated in South-East Asia. This expansion of rubber plantations affects different ESS such as carbon storage, availability and quality of water and threatens biodiversity in this highly biodiverse region. In order to analyze these impacts the first task was to give a comprehensive overview about publications concerning ESS and biodiversity in rubber cultivation systems. A thorough literature review showed that the majority of publications concentrated on single or few ESS, which does not match the demands of decision-makers. In order to make sound decisions for land-use planning or developing Payments for Ecosystem Services Schemes a holistic view including multiple services. In order to fill this knowledge gap, the second task was to analyze the impacts of rubber on the ESS carbon storage, soil erosion, water availability and water quality and economically and socially related ESS, such as income and livelihood security. Although there are still great uncertainties about carbon storage in different land-use systems there are hints that the carbon storage in rubber plantations is lower than in natural forests. Concerning erodibility, rubber plantations increase the soil erosion risk compared to natural forests. Rubber cultivation also affects the local and regional water balance. Since rubber production in monocultures requires the use of huge amounts of pesticides and chemical fertilizers which enter the aquatic system by rainfall-induced run-off, water quality for humans and aquatic organisms is as well threatened. Undoubtedly, from an economic point of view the introduction of rubber resulted in significant increases in household income and is hence a possibility to move households and communities out of poverty. However, by deciding to grow rubber, farmers are committing themselves for decades to come and are thus dependent on a single product, which exposes them to further risks. In addition, there are ecological hazards due to crop diseases, pests, unfavorable weather conditions or changes in climate. The review of studies clearly indicates that increasing rubber cultivation in the GMS is accompanied by various problems and threats to farmers and the environment. Therefore, the development of more sustainable land-use concepts is required. Concordantly, suggestions for land-use change are based on system diversification and forest restoration, which both require economic incentives for farmers. The next part of this dissertation deals with the development of a biodiversity indicator (based on selected flora and fauna species) that can be included in existing biodiversity models to show the impact that different rubber cultivation scenarios will have on various species groups. A combination of multi-species data supplemented with literature data was used and included flora, vertebrates and invertebrates. The resulting indicator was used as input into an established ESS assessment framework. Finally, a current land-use map from 2007 was compared with two scenarios. In order to get a more detailed picture, sub-groups of biodiversity were analyzed as well. First, a sub-group of “human use species” category was assessed which included only species which are directly used by humans. Second, the sub-group “red list species”, consisting of red list plants and mammals was analyzed separately to include the conservational aspect. The results showed that when considering the indices from the category “human use species” there is less of an impact between the scenarios, because medicinal plants for example are still commonly distributed within rubber plantations, albeit with different species (generalists, ruderal flora). This leads to an important conclusion: not only the decision on “what” is analyzed (biodiversity), but also “how” it is analyzed (groups of different species) considerably influences the results. To complete this dissertation the transferability of this place-based research to other regions of the world was tested to assess the relevance beyond the study area. To do this the system of land archetypes was used, which utilizes a wide range of land-use intensity metrics and incorporates simultaneously environmental and socio-economic conditions. In a first step, the ‘project archetype’ was defined, based on a synthesis of global land system indicators. For the project Sustainable Rubber Cultivation in the Mekong Region, only few of the 32 global indicators did not closely match the local reality. The transferability potential for the GMS was quite high and therefore emphasizes the importance of the project results for this huge region.
Parasites, depredators, and limited resources as potential drivers of winter mortality of feral honeybee colonies in German forests
(2023) Kohl, Patrick L.; Rutschmann, Benjamin; Sikora, Luis G.; Wimmer, Norbert; Zahner, Volker; D’Alvise, Paul; Hasselmann, Martin; Steffan-Dewenter, Ingolf; Kohl, Patrick L.; Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Würzburg, Germany; Rutschmann, Benjamin; Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Würzburg, Germany; Sikora, Luis G.; NaturKonzept, Pfullingen, Germany; Wimmer, Norbert; Bayerische Landesanstalt Für Wald Und Forstwirtschaft, Freising, Germany; Zahner, Volker; Forest Ecology and Management, University of Applied Sciences Weihenstephan-Triesdorf, Freising, Germany; D’Alvise, Paul; Institute for Medical Microbiology and Hygiene, University Hospital Tübingen, Tübingen, Germany; Hasselmann, Martin; Department of Livestock Population Genomics, Institute of Animal Science, University of Hohenheim, Stuttgart, Germany; Steffan-Dewenter, Ingolf; Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Würzburg, Germany
Wild honeybees ( Apis mellifera ) are considered extinct in most parts of Europe. The likely causes of their decline include increased parasite burden, lack of high-quality nesting sites and associated depredation pressure, and food scarcity. In Germany, feral honeybees still colonize managed forests, but their survival rate is too low to maintain viable populations. Based on colony observations collected during a monitoring study, data on parasite prevalence, experiments on nest depredation, and analyses of land cover maps, we explored whether parasite pressure, depredation or expected landscape-level food availability explain feral colony winter mortality. Considering the colony-level occurrence of 18 microparasites in the previous summer, colonies that died did not have a higher parasite burden than colonies that survived. Camera traps installed at cavity trees revealed that four woodpecker species, great tits, and pine martens act as nest depredators. In a depredator exclusion experiment, the winter survival rate of colonies in cavities with protected entrances was 50% higher than that of colonies with unmanipulated entrances. Landscapes surrounding surviving colonies contained on average 6.4 percentage points more cropland than landscapes surrounding dying colonies, with cropland being known to disproportionately provide forage for bees in our study system. We conclude that the lack of spacious but well-protected nesting cavities and the shortage of food are currently more important than parasites in limiting populations of wild-living honeybees in German forests. Increasing the density and diversity of large tree cavities and promoting bee forage plants in forests will probably promote wild-living honeybees despite parasite pressure.