Knut Kaiser

Status and dynamics of the Kobresia pygmaea ecosystem on the Tibetan plateau.

Abstract This paper provides information about the distribution, structure, and ecology of the worlds largest alpine ecosystem, the Kobresia pygmaea pastures in the southeastern Tibetan plateau. The environmental importance of these Cyperaceae mats derives from the extremely firm turf, which protects large surfaces against erosion, including the headwaters of the Huang He, Yangtze, Mekong, Salween, and Brahmaputra. The emphasis of the present article is on the climate-driven evolution and recent dynamics of these mats under the grazing impact of small mammals and livestock. Considering pedological analyses, radiocarbon datings, and results from exclosure experiments, we hypothesize that the majority of K. pygmaea mats are human-induced and replace forests, scrub, and taller grasslands. At present, the carrying capacity is increasingly exceeded, and reinforced settlement of nomads threatens this ecosystem especially in its drier part, where small mammals become strong competitors with livestock and the removal of the turf is irreversible. Examples of rehabilitation measures are given.

A Lateglacial palaeosol cover in the Altdarss area, southern Baltic Sea coast (northeast Germany): investigations on pedology, geochronology and botany

A new site with Lateglacial palaeosols covered by 0.8 - 2.4 m thick aeolian sands is presented. The buried soils were subjected to multidisciplinary analyses (pedology, micromorphology, geochronology, dendrology, palynology, macrofossils). The buried soil cover comprises a catena from relatively dry (’Nano’-Podzol, Arenosol) via moist (Histic Gleysol, Gleysol) to wet conditions (Histosol). Dry soils are similar to the so-called Usselo soil, as described from sites in NW Europe and central Poland. The buried soil surface covers ca. 3.4 km 2 . Pollen analyses date this surface into the late Allerod. Due to a possible contamination by younger carbon, radiocarbon dates are too young. OSL dates indicate that the covering by aeolian sands most probably occurred during the Younger Dryas. Botanical analyses enables the reconstruction of a vegetation pattern typical for the late Allerod. Large wooden remains of pine and birch were recorded.

Potential of palaeosols, sediments and archaeological features to reconstruct Late Glacial fire regimes in northern Central Europe – case study Grabow site and overview

Late Glacial fires in Northern Germany are well known from different geoarchives such as palaeosols, (limnic) sediments and archaeological sites. This has evoked the question if the fire regime during the Allerod and Younger Dryas was driven exclusively by natural agents (temperature, precipitation, vegetation pattern) or was – at least to some extent – a result of anthropogenic burning. We contribute to this question by examining on-site and off-site archives in the Jeetzel valley at the Late Palaeolithic site Grabow 15 (N-Germany). The spatial analysis of the charcoal distribution and biomarkers (“black carbon”) in an on-site test area enabled a detailed reconstruction of human burning activities during the early Allerod. A determination of the charred wood taxa allowed a reconstruction of the local vegetation pattern during the time of human occupation. The evidence of man-made fire was compared to the general occurrence of charcoal particles in two palaeochannels that provided archives for palynological and sedimentological analysis for the time span from the Allerod to the early Holocene. Based on the reconstructed local vegetation patterns, human occupation phases and water levels we conclude that human presence during the early Allerod must have increased the input of charcoal and biomarkers into the local sediments. During the Younger Dryas no human contribution to the local charcoal influx was detected. We concluded that future studies must considerate the very local impact of man-made fires in much greater detail.

Klimawandel und Wasserhaushalt

Die kostengunstige Deckung des Wasserbedarfs der Nutzer bei gleichzeitiger Erhaltung der Okosystemfunktionen von Gewassern stellt eine stetig zu erfullende Aufgabe der Wasserwirtschaft dar. Eine nachhaltige Bewirtschaftung hoch beanspruchter Wasserressourcen-Systeme ist dabei nur mOglich, wenn fortlaufend solche Methoden und Verfahren evaluiert und weiterentwickelt werden, die Veranderungen und Anpassungen des Wasserwirtschaftssystems erlauben. Es gilt, Wasserdargebot und Wasserbedarf durch dargebotsund/ oder bedarfsorientierte Einflussnahmen unter minimalen Kosten bzw. bei maximaler Nachhaltigkeit in ubereinstimmung zu bringen (Grunewald 2008a; Abb. 2-1).

A submerged pine forest from the early Holocene in the Mecklenburg Lake District, northern Germany

(1) GFZ German Research Centre for Geosciences, Potsdam, Germany (kaiserk@gfz-potsdam.de), (2) Nature Park Stechlin-Ruppiner Land, Menz, Germany, (3) University of Potsdam, Institute of Earthand Environmental Science, Potsdam, Germany, (4) University of Greifswald, Institute of Geography and Geology, Greifswald, Germany, (5) University of Greifswald, Institute of Botany and Landscape Ecology, Greifswald, Germany, (6) Müritzeum, Waren (Müritz), Germany, (7) Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany, (8) Nature and Biodiversity Conservation Union (NABU), Berlin, Germany

Can We Use Tree Rings of Black Alder to Reconstruct Lake Levels? A Case Study for the Mecklenburg Lake District, Northeastern Germany

In this study, we explore the potential to reconstruct lake-level (and groundwater) fluctuations from tree-ring chronologies of black alder (Alnus glutinosa L.) for three study lakes in the Mecklenburg Lake District, northeastern Germany. As gauging records for lakes in this region are generally short, long-term reconstructions of lake-level fluctuations could provide valuable information on past hydrological conditions, which, in turn, are useful to assess dynamics of climate and landscape evolution. We selected black alder as our study species as alder typically thrives as riparian vegetation along lakeshores. For the study lakes, we tested whether a regional signal in lake-level fluctuations and in the growth of alder exists that could be used for long-term regional hydrological reconstructions, but found that local (i.e. site-specific) signals in lake level and tree-ring chronologies prevailed. Hence, we built lake/groundwater-level reconstruction models for the three study lakes individually. Two sets of models were considered based on (1) local tree-ring series of black alder, and (2) site-specific Standardized Precipitation Evapotranspiration Indices (SPEI). Although the SPEI-based models performed statistically well, we critically reflect on the reliability of these reconstructions, as SPEI cannot account for human influence. Tree-ring based reconstruction models, on the other hand, performed poor. Combined, our results suggest that, for our study area, long-term regional reconstructions of lake-level fluctuations that consider both recent and ancient (e.g., archaeological) wood of black alder seem extremely challenging, if not impossible.