Biodiversity, Conservation and Cultural History
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Sycamore maple wooded pastures in the Northern Alps: Biodiversity, conservation and cultural history Inauguraldissertation der Philosophisch-naturwissenschaftlichen Fakultät der Universität Bern vorgelegt von Thomas Kiebacher von Brixen (Italien) Leiter der Arbeit: Prof. Dr. Christoph Scheidegger Dr. Ariel Bergamini PD Dr. Matthias Bürgi WSL Swiss Federal Research Institute, Birmensdorf Sycamore maple wooded pastures in the Northern Alps: Biodiversity, conservation and cultural history Inauguraldissertation der Philosophisch-naturwissenschaftlichen Fakultät der Universität Bern vorgelegt von Thomas Kiebacher von Brixen (Italien) Leiter der Arbeit: Prof. Dr. Christoph Scheidegger Dr. Ariel Bergamini PD Dr. Matthias Bürgi WSL Swiss Federal Research Institute, Birmensdorf Von der Philosophisch-naturwissenschaftlichen Fakultät angenommen. Bern, 13. September 2016 Der Dekan: Prof. Dr. Gilberto Colangelo Meinen Eltern, Frieda und Rudolf Contents Abstract ................................................................................................................................................... 9 Introduction ........................................................................................................................................... 11 Context and aims ............................................................................................................................... 13 The study system: Sycamore maple wooded pastures ..................................................................... 13 Biodiversity ........................................................................................................................................ 15 Conservation ..................................................................................................................................... 17 Cultural history .................................................................................................................................. 20 ReFerences ............................................................................................................................................. 22 Chapter 1 ............................................................................................................................................... 33 Hidden crown jewels: The role oF tree crowns For bryophyte and lichen species richness in sycamore maple wooded pastures Chapter 2 ............................................................................................................................................... 79 Epiphyte species richness in a sylvo-pastoral system: Contrasting eFFects oF connectivity, tree structure and environmental conditions on bryophytes and lichens Chapter 3 ............................................................................................................................................. 127 Solitary trees increase the diversity oF vascular plants and bryophytes on pastures Chapter 4 ............................................................................................................................................. 167 Die Kulturgeschichte der Bergahornweiden (The cultural history oF sycamore maple wooded pastures) Chapter 5 ............................................................................................................................................. 231 Knowledge transFer and sensitisation activities Conclusions and outlook ..................................................................................................................... 245 Acknowledgements ............................................................................................................................. 247 Erklärung ............................................................................................................................................. 251 Curriculum vitae .................................................................................................................................. 253 Abstract Sycamore maple wooded pastures are a traditional land management system in the montane region oF the northern European Alps. So Far they have hardly been recognized as a distinct cultural landscape and they have been neglected from biodiversity research and from a conservation perspective. At six sites along the main area of occurrence oF sycamore maple wooded pastures in the montane region oF the northern Alps I assessed (1) the biodiversity of epiphytic bryophytes and lichens on the sycamore maple (Acer pseudoplatanus) trees; (2) the eFFects oF a range oF variables on species richness oF these organisms considering various Functional subgroups; (3) driving factors For the occurrence oF three focal species of major conservation concern (Tayloria rudolphiana, Orthotrichum rogeri, Lobaria pulmonaria); (4) the eFFects oF the trees on the ground vegetation (vascular plants and bryophytes); and, (5) the cultural and historical background oF the system, i.e. its spatial and structural evolution, management practices, usage oF the trees, and how sycamore maple wooded pastures are perceived and appraised by the local communities. Sycamore maple wooded pastures were Found to be characterized by an outstandingly high biodiversity, including many red-listed species. A total number oF 899 species on the trees and pastures surveyed were Found. On a single tree up to 60 bryophyte or 67 lichen species may occur. Bryophytes and lichens as well as their functional subgroups were differently and sometimes contrastingly aFFected by tree parameters, environmental variables and connectivity measures. Most strikingly, connectivity to neighbouring trees was crucial For lichens but not For bryophytes. However, the occurrence oF the bryophyte species T. rudolphiana was also Found to depend on connectivity at small spatial scales whereas the lichen L. pulmonaria did not. In contrast to most other species the pioneer bryophyte species O. rogeri was more Frequent on younger trees. The ground vegetation was also very species rich with up to 60 bryophyte species and 74 vascular plant species per plot (30 m2). The sycamore maple trees had a strong positive eFFect on alpha- and beta-diversity oF the ground vegetation, even on intensively managed pastures. Within the last 100 years the area occupied by sycamore maple wooded pastures generally decreased and at many sites young trees are scarce today. In historical times the main function of the trees was to provide shelter For grazing animals and the leaves were economically important as they were used as litter. Although nowadays the sycamore maple trees lost most oF their economic importance, Farmers and local communities generally still have a positive attitude towards them. Sycamore maple wooded pastures are a unique sylvo-pastoral ecosystem where the trees are keystone structures For biodiversity because they Foster high species richness at small spatial scales. For the conservation oF high overall species richness and oF threatened species it is crucial to sustain a wide range oF tree sizes and ages in suFFicient densities. Specific conservation policies need to be established For a sustainable long-term preservation oF sycamore maple wooded pastures. These policies may consist in creating financial incentives for the plantation of trees and the process of creating public awareness, which has successfully been initiated in the course oF this PhD project, should be advanced. 9 10 INTRODUCTION Introduction Context and aims In the course oF the Neolithic revolution which started about 12'500 years ago (Barker 2009) man’s impact on nature drastically changed (Simmons 2011). BeFore, man as a hunter and gatherer, similar to animals, merely reduced the abundance oF species which served his uses (Marsh 1864, Foley et al. 2013) and extirpated probably some large mammals at the end oF the Pleistocene (e.g. Alroy 2001). Then, the shiFt to the systematic production oF Food in settled agriculture considerably disturbed the natural (without human inFluence) turnover oF species, i.e. natural rate oF extinction and emergence oF new species. The transition to settled agriculture drastically reduced and even extirpated some species but also promoted the evolution of new taxa (Marsh 1864, Goudie 2013), which was driven primarily by the creation oF new habitats and the destruction oF natural ones (Goudie 2013). The invention oF agricultural practises allowed a strong expansion oF the human population (Gupta 2004). Nowadays in large areas oF the world’s land surFace, like For example in central Europe, hardly any patch of land can be Found which is not directly inFluenced by human activities (Ellenberg and Leuschner 1996). Compared to the natural state, man-made habitats host diFferent assemblages of species and the species richness of these communities can be either strongly reduced or increased (Bazzaz 1983) depending on a range oF Factors oF which management intensity (e.g. in terms oF nutrient input) is among the most important (Klimek et al. 2007). Man-made sylvo-pastoral systems, For instance, are among the most species-rich habitats in Europe (Kull and Zobel 1991, BeauFoy 1998, Sammul et al. 2008, Miklín and Čížek 2014). The high species richness of these systems can be explained by a generally low management intensity in combination with disturbances of intermediate Frequency and intensity (see Huston 1979, 1994) by the grazing animals and a high structural heterogeneity at small spatial scales leading to high small scale variations