Climate Change and Biodiversity in Temperate Montane Forests - Patterns, Processes and Predictions
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Climate Change and Biodiversity in Temperate Montane Forests - Patterns, Processes and Predictions vorgelegt von Diplom-Umweltwissenschaftler Claus Bässler aus Hohenau Von der Fakultät VI - Planen Bauen Umwelt der Technischen Universität Berlin zur Erlangung des akademischen Grades Doktor der Naturwissenschaften Dr. rer. nat. genehmigte Dissertation Promotionsausschuss: Vorsitzender: Prof. Dr. Joachim Erber Berichter: Prof. Dr. Frank Dziock Berichter: Prof. Dr. Ingo Kowarik Tag der wissenschaftlichen Aussprache: 18.07.2008 Berlin 2008 D 83 Contents Preface iii Abstract v Zusammenfassung ix Part A: Synthesis 1 1. Aims of the Study 1 1.1 Postulates 1 1.2 Specific objectives 1 2. Material and Methods 3 2.1 Study sites 3 2.3 Methods used to test the postulates 3 3. Trend of air temperature for the Bavarian Forest 6 4. Conceptual Framework of Climate Change Research 8 4.1 Study design 8 4.2 Environmental data 10 4.3 Biological data 12 4.4 Worldwide climate change research - a comparison 13 5. The surrogate factor altitude and its influence on community compositions 14 6. Distribution patterns along the altitudinal gradient 16 7. Effects of climate among habitat predictors along the altitudinal gradient 18 8. High montane species as climate change indicators 20 9. Extinction risk for high montane species due to global warming 21 10. Conclusions and recommendations for monitoring of climate change 24 References i Part B: Research Papers 34 I Bässler, C. 35 Klimawandel - Trend der Lufttemperatur im Inneren Bayerischen Wald (Böhmerwald) Climate Change - trend of air temperature in the Innerer Bayerischer Wald (Bohemian Forest) Manuscript in press (Silva Gabreta 2008 vol. 14 (1) p. 1-8)) II Bässler, C., Förster, B., Moning, C. , Müller, J. 58 The BIOKLIM Project: Biodiversity Research between Climate Change and Wilding in a temperate montane forest – The conceptual framework. Manuscript under revision III Bässler, C., Müller, J., Dziock, F. 85 Identification of climate sensitive zones for plants in montane forests. Manuscript under revision IV Bässler, C., Müller, J., Dziock, F. 103 Effects of climate, forest structure and habitat continuity on wood-inhabiting fungi in Low Mountain range forests. Submitted manuscript V Bässler, C., Müller, J., Kneib, T., Hothorn, T., Dziock, F. 125 Estimation of the extinction risk of high montane species after global warming and comparison of their suitability as cross-taxon indicators Manuscript VI Müller, J., Bässler, C., Strätz, C., Klöcking, B., Brandl, R. 164 Molluscs and climate warming in forest of a low mountain range. Submitted manuscript ii Preface In 2007 the Intergovernmental Panel on Climate Change (IPCC) published its fourth Assessment Report summarizing the current scientific understanding of impacts of climate change on natural, managed and human systems, the capacity of these systems to adapt and their vulnerability (Ipcc 2007a). According to this report, observational evidence from all continents and most oceans shows that many natural systems are being affected by regional climate changes, particularly temperature increases. The resilience of many ecosystems is likely to be overpowered this century by an unprecedented combination of climate change, associated disturbances (e.g., flooding, drought, wildfire, insects, ocean acidification), and other drivers of global change (e.g. land use change, pollution, overexploitation of resources) (Sala et al. 2000, Travis 2002, Hooper et al. 2005). Approximately 20-30% of plant and animal species assessed so far are likely to be at greater risk of extinction if increases in global average temperature exceed 1.5-2.5 °C. For increases in global average temperature exceeding 1.5-2.5°C and for concomitant atmospheric carbon dioxide concentrations, major changes are projected to occur in ecosystem structure and function as well as species’ ecological interactions and geographic ranges, with predominantly negative consequences for biodiversity (Ipcc 2007a). As a result of this rapid rate of change there is a growing need to record and analyse the present state of ecosystems, to establish relationships of species to the environment, and to use this data for assessing and predicting further changes caused by anthropogenic influence (land use and climate change) (Loreau et al. 2001, Sutherland et al. 2006). It is difficult to measure the impacts of increasing air temperature on biodiversity. But ecological changes in the phenology and distribution of plants and animals are occurring in all well studied marine, freshwater, and terrestrial groups. These observed changes are heavily biased in the directions predicted for global warming and have been linked to local or regional climate change through correlations between climate and biological variation, field and laboratory experiments, and physiological research (Walther et al. 2002, Parmesan 2006) but the potential effect on complex communities is little understood. We need significantly improved models of the effects of climate change on the distribution of species and habitats. To achieve this, ecological research on climatic tolerances of species and habitats must be intensified (Sutherland et al. 2006). Furthermore, according to the latter study there is an urgent need to find out which species are the best indicators of the effects of climate change on natural communities, which habitats and species might be lost completely because of climate change, what time lags can be expected between climate change and ecological iii change, and what the likely relationship will be between the extent of climate change and the pattern of species extinction. Despite much discussion and a high level of research activity in various disciplines on assessing the impact of global change caused by temperature increase on biodiversity and natural systems, there is still a major lack of knowledge at relevant temporal and spatial scales (Sutherland et al. 2006). Currently, the most relevant physical and temporal scale of ecological investigations is a local one (Walther et al. 2002). As a response to mainly the expected increase in temperature, a powerful effect on biological systems is very likely and the most significant effects of climate change will occur on regional scales in the next 50 years. Current climate change predictions for the study area at a regional scale show increasing temperatures until the end of the 21st century (Spekat et al. 2007). More than half of Central Europe consists of mountain areas and most of these are low ranges covered by forest (CIPRA 2007). The aim of this study is to contribute to the knowledge of expected effects of climate change on these low mountain range forest ecosystems in Central Europe. The thesis is based on six manuscripts. The first concerns the magnitude of the physical change (air temperature) related to the study area and discusses the necessity of climate change research efforts. Building on this, the second manuscript relates the climate change research framework to the regional scale, thus creating a broad basis for analyses. The third paper deals with the dependency of vascular plants on altitude and examines the character of changes (continuous/discrete), in order to reveal unknown species distribution patterns in low mountain ranges and identify climate sensitive zones for future climate change monitoring. The confounding environmental effects occurring along the altitudinal gradient for forest structure dependent species (wood inhabiting fungi and molluscs) are examined in the fourth and six papers, by revealing the effect of climate under consideration of forest structure factors, both co-varying along the altitudinal gradient. The fifth paper determines the extinction risk for high montane species, expected to be very vulnerable to climate change, and their suitability for use as indicators and cross-taxon indicators in further monitoring. iv Abstract Globally detected temperature change varies strongly on a regional scale; sometimes trend values are negative. Thus, the first aim of this study is to analyse the trend of air temperature for the study area based on data from selected meteorological stations and to reveal regional patterns of climate change. Mean air temperature; mean daily minimum and maximum temperatures were considered. After data preparation, checking of data by time series analysis (trend and cutpoint analysis) and examination of spatial and time representation was carried out. To investigate orographic differences, data from two meteorological stations representative for hillside or valley locations were analysed for the time frame 1948-2002. Predominantly positive trends were noticeable for the period under consideration. The highest trend of mean air temperature change was calculated for May (0.04 K a-1 for hillside locations and 0.03 K for valley locations) and August (0.02 K a-1 for hillside locations and 0,03 K for valley locations). Thus, there was a trend of 0.02 K a-1 (hillside) and 0.01 K a-1 (valley) increase for the growing season (May-August). More distinct were the trends of the mean monthly minimum temperature, where almost all trends were positive. In contrast, the mean maximum temperature showed a much more moderate reaction. There is a common cutpoint for the mean annual air temperature time series under study (1948-2002) in 1988. Hence, the detected overall trend is mostly a result of the increasing temperature since this point in time. To summarize: climate change is taking place in our low mountain range study