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Tidal flats represent the transition zone between the terrestrial and marine realm. They are subject to pronounced dynamics due to distinct tidal and seasonal variations of physical, chemical, and biological parameters significantly influencing redox-sensitive element cycles. Thus, redox-sensitive trace metals may be suitable indicators for variations in bioproductivity and microbial activity. Therefore, seasonal and tidal dynamics of manganese, iron, molybdenum, uranium, and vanadium were studied in the water column and sediments of tidal systems of the German Wadden Sea (southern North Sea) in the years 2007 to 2009 involving also previously analysed data from year 2002. To demonstrate the response of the trace metal cycles on phytoplankton blooms and enhanced biological activity time series data of nutrients and phytoplankton dynamics were also involved in this study. Pronounced cycling is seen for pelagic manganese revealing distinctly higher values during low tide. Complex seasonal cycling showing maxima of dissolved manganese in spring and late summer and a depletion period in early summer is caused by benthic-pelagic coupling and reflection of exhaustion and replenishing periods in the surface sediments. Vanadium dynamics are coupled to the manganese cycling due to vanadium scavenging and release during manganese oxide formation and reduction, respectively. Molybdenum and uranium behave almost conservatively following changes in salinity and thus, being slightly enhanced during high tide. Deviations from conservative behaviour are found to occur during breakdowns of summer phytoplankton blooms. In the following, significant enrichments of manganese, molybdenum, iron, and uranium are observed in the shallow pore waters. These coherences are assumed to be caused by a tight coupling of geochemical, biological, and sedimentological processes. Intense release of organic matter during the breakdowns of algae blooms leads together with enhanced bacterial activity in summer to the formation of organic- and trace metal-rich aggregates which are deposited and incorporated into the tidal surface sediments. Microbial decomposition of the aggregates and corresponding shifts in redox-conditions effect a release of dissolved trace metals into the pore water. Subsequently, the trace metals are fixed in the sediment as sulphides, adsorbed to organic compounds or released to the overlying bottom water. Furthermore, two tidal systems, one from the East Frisian and one from the North Frisian Wadden Sea are compared. Although, both areas show different hydrodynamical, sedimentological, and ecological conditions similar manganese dynamics are observed implying that this is a common behaviour in the entire Wadden Sea. However, distinct quantitative differences appear showing a 6-fold higher level of dissolved manganese in the water column of the East Frisian area. This is explained by a higher manganese release from tidal flat sediments and a larger sediment area/water volume ratio compared to the North Frisian area. Detailed time-series data of the nutrients phosphate, silica, and nitrite+nitrate are used to verify model simulations and to calculate nutrient export budgets considering tidal and seasonal variations. The model results imply an export of nutrients from the tidal flats into the open waters of the German Bight which is in the same order of magnitude as the combined discharge of the rivers Elbe, Weser, and Ems. To investigate the importance of the Wadden Sea as a potential manganese source for the North Sea, transects were carried out into several tidal flat areas of the North Frisian Wadden Sea. The results suggest that the North Frisian Wadden Sea is a less important source for dissolved manganese compared to the East Frisian area. In contrary, the export of particulate manganese seems to be more important showing distinctly higher concentrations in the North Frisian study areas in summer. The influence of sediment permeability and bioturbation on trace metal budgets of the pore waters are investigated in natural and experimentally manipulated tidal flat sediments. Advective pore water transport in highly permeable sandy sediments and bioturbation promote exchange processes at the sediment/water interface probably leading to reduced nutrient and trace metal enrichments in the shallow pore waters. Furthermore, the penetration of oxygen into deeper sediment layers induces a release of sulphidic bound molybdenum to the pore water. During laboratory experiments with natural anoxic sediments an effective oxidative molybdenum release is determined during resuspension of the sediments in oxic seawater. Thus, pronounced sediment resuspension during storm events is suggested to cause significant release of molybdate from displaced anoxic sediment components thereby enhancing the molybdate level of the open water column. In addition to the examination of recent biogeochemical processes, the paleo-environmental influence on geochemical and microbiological processes in Holocene and Pleistocene sediments of the East Frisian study area were analysed in an interdisciplinary study. It is found that the microbial abundance and activity are higher in the Holocene than in the Pleistocene sediments. However, this is mainly caused by present environmental conditions. The impact of the paleo-environment on the microbiology is less pronounced. The lithological succession affects hydrological processes which enable the transfer of electron donors and acceptors for present early diagenetic processes into deep sediment layers. The paleo-environmental imprint is still detectable but the modern biogeochemical processes dominate in the sediment-pore water system.
This thesis aims at bridging the gap of deficient understanding of effective buffer zone management. The overall research goal of the thesis is to evaluate buffer zone effectiveness and to identify factors influencing effective buffer zone management in forest biosphere reserves. To address the multi-facetted issue of buffer zone effectiveness an integrative research design was applied. To answer the raised research questions a combination of social science (quantitative and qualitative approaches) and natural science (remote sensing) was chosen. To gain global insights into buffer zone management (research question 1) the quantitative approach of social science research was chosen. As part of a global telephone survey of BR management conducted by the research project in which the thesis was embedded, BR managers were asked to evaluate different management aspects. Between July and December 2006, managers from 225 BRs in 79 countries were interviewed, which corresponds to an overall response rate of 42 %. Answers were statistically analyzed using SPSS 17.0. To obtain detailed information of factors influencing buffer zone management (research question 2) the qualitative social science research approach was applied. A case study was conducted in the Lore Lindu Biosphere Reserve, Sulawesi, Indonesia between March and May 2008. Following the snowball sampling approach 47 semi-structured interviews and seven group discussions were carried out representing the local, sub-national, and national level associated with the BR management. These interviews and discussions provide important insights into the institutional dimensions and their interaction within the context of BR management including e.g. implementation of rules and the distribution of responsibilities for buffer zone management. Interviews were conducted in the national language Bahasa Indonesia, fully recorded, and subsequently transcribed and translated into English. Analysis was carried out with ATLAS.ti to specify categories and to formulate theorems. To evaluate buffer zone effectiveness in terms of reducing deforestation in the core area of Lore Lindu Biosphere Reserve (research question 1), satellite image analysis was performed using a GIS. A time series of LANDSAT scenes from 1972, 1983, 1999, 2002, and 2007 was used to classify homogeneous areas of forest cover to ultimately detect deforestation. Deforestation rate was computed for the periods before and after management establishment in 1998. The combination of all three research methods provided important insights into buffer zone management of BRs. Thus, based on these findings, recommendations to improve buffer zone management (research question 3) could be drawn. Overall, the evaluation of buffer zones depicts their importance for BR management effectiveness. Analysis revealed buffer zone effectiveness as important success factor, while it explicitly depends on both the implementation of the BR concept at the national level and coordination of stakeholders on the local level. As more and more PAs create buffer zones to integrate the local people, they may face similar problems. The case study from Lore Lindu exhibited important preconditions for successful buffer zone management. From a methodological perspective the thesis calls for the need of integrated research approaches across disciplines to adequately assess both buffer zone and PA effectiveness. Generally, it is recommended to pay special attention to pre-Seville BRs in the future, since most of these BRs still lack the three zone scheme. Analysis of the case study area revealed particular weaknesses in implementing central elements for effective BR management, such as the four goals of the Seville Strategy, even 15 years after inauguration. Thus, the thesis shows that not only the quantity of PAs but also the quality of its management and thus effectiveness is an important indicator for global conservation targets. Finally, it can be summarized that the idea of establishing buffer zones within BRs and PAs in general, is the right way forward to enhance PA effectiveness and to achieve global reduction of biodiversity loss. Integrating the people living within and adjacent to PAs, must be given more attention in the future. Establishment of buffer zones, where this integration and cooperation is a necessity, should be the central conservation measure, not only within BRs but also within PAs in general.
The dissertation aims at developing means to integrate conservation and development in biosphere reserves in Madagascar. Despite a multitude of concepts such as UNESCO biosphere reserves, Integrated Conservation and Development Projects and community-based natural resource management, gaps between conservation and development remain to exist. In a qualitative case study in Mananara-Nord and Sahamalaza Iles-Radama Biosphere Reserves in Madagascar data was collected on biosphere reserve management, local use of natural resources and socio-cultural aspects that influence natural resource use. Furthermore, natural values local people associate with the forest were investigated. Analysis revealed that management capacities constitute a limiting factor in biosphere reserve management. Collaboration between management, local people and international organisations fosters the achievement of both conservation and development. However, collaboration is only possible if (i) clear rules are formulated and (ii) partners have a vision in common. Based on the theory of social capital, newly introduced and locally existent rules/institutions having an influence on the use of natural resource were categorized in bonding, linking and bridging social capital. Furthermore, the perception of natural values was classified in instrumental and non-instrumental values and assigned to ecosystem services identifying the importance of nature for human well-being. With the capabilities approach Amartya Sen defined human well-being as the achievement of those capabilities a person considers valuable. This includes aspects that assure livelihoods on the one hand and aspects that are conducive to well-being on the other, thus both being relevant for development. In the dissertation capabilities are based on both instrumental and non-instrumental natural values and consequently offer an opportunity to demonstrate and characterise the relationship between nature and human well-being. Social and natural values provide orientation for a biosphere reserve management. The category bonding social capital (social values) describes local socio-cultural aspects in communities and their importance for collaborative processes. Natural values provide the management with guiding principles to foster nature conservation and to integrate locally existent capabilities. Supporting and furthering these capabilities enables the development of new capabilities of all concerned persons. The dissertation demonstrates various possibilities to build bridges between (i) nature conservation and development, (ii) natural and social sciences, (iii) formal regulations and local socio-cultural aspects and (iv) diverse actors. Implementation of a social monitoring is recommended together with local stewards and Malagasy students to collect information about the perception of natural and social values and use them as guiding principles for biosphere reserves. Collaboration with national and international scientific institutions can foster this process.