Arctic environments are subject to acute nitrogen deposition events, in which 40% or more of annual atmospheric N input can be deposited as acidic rainfall in less than one week. The overall aim of this research was to investigate the impact of acute N deposition events upon soil microbial communities in High Arctic tundra. A plot scale field experiment, established on the High Arctic tundra (Ny-Ålesund, Svalbard), and a microcosm experiment, were used to simulate acute N deposition over the summer by the application of NH4NO3 solution at ~pH 4, at rates of 0.4, 4 and 12 kg N ha-1 yr-1. Changes in soil characteristics were measured on soil samples from the organic and mineral horizons. Variation in the structure and abundance of bacterial, archaeal, and fungal communities and in the presence and abundance of N-cycling functional guilds were investigated using molecular (DNA)-based approaches such as Terminal Restriction Fragment Polymorphism (T-RFLP) and quantitative-PCR. T-RFLP analysis revealed significant (P
The cryosphere stands for environments where water appears in a frozen form. It includes permafrost, glaciers, ice sheets, and sea ice and is currently more affected by Global Change than most other regions of the Earth. In the cryosphere, limited water availability and subzero temperatures cause extreme conditions for all kind of life which microorganisms can cope with extremely well. The cryosphere’s microbiota displays an unexpectedly large genetic potential, and taxonomic as well as functional diversity which, however, we still only begin to map. Also, microbial communities influence reaction patterns of the cryosphere towards Global Change. Altered patterns of seasonal temperature fluctuations and precipitation are expected in the Arctic and will affect the microbial turnover of soil organic matter (SOM). Activation of nutrients by thawing and increased active layer thickness as well as erosion renders nutrient stocks accessible to microbial activities. Also, glacier melt and retreat stimulate microbial life in turn influencing albedo and surface temperatures. In this context, the functional resilience of microbial communities in the cryosphere is of major interest. Particularly important is the ability of microorganisms and microbial communities to respond to changes in their surroundings by intracellular regulation and population shifts within functional niches, respectively. Research on microbial life exposed to permanent freeze or seasonal freeze-thaw cycles has led to astonishing findings about microbial versatility, adaptation, and diversity. Microorganisms thrive in cold habitats and new sequencing techniques have produced large amounts of genomic, metagenomic, and metatranscriptomic data that allow insights into the fascinating microbial ecology and physiology at low and subzero temperatures. Moreover, some of the frozen ecosystems such as permafrost constitute major global carbon and nitrogen storages, but can also act as sources of the greenhouse gases methane and nitrous oxide. In this book we summarize state of the art knowledge on whether environmental changes are met by a flexible microbial community retaining its function, or if the altered conditions also render the community in a state of altered properties that affect the Earth’s element cycles and climate. This book brings together research on the cryosphere’s microbiota including permafrost, glaciers, and sea ice in Arctic and Antarctic regions. Different spatial scales and levels of complexity are considered, spanning from ecosystem level to pure culture studies of model microbes in the laboratory. It aims to attract a wide range of parties with interest in the effect of climate change and/or low temperatures on microbial nutrient cycling and physiology.
In the past century, anthropogenic activities have increased N input drastically to terrestrial ecosystems and influenced the global N cycle. Especially temperate forest ecosystems are affected in their productivity, species composition, soil chemistry and water quality. N input to forest ecosystems is retained in trees and soil. Excessive N is leached out or released as gases. The retention of N input in soils is mainly influenced by the stability of soil organic matter (SOM). Many forests in central Europe and North America have been subjected to N saturation, i.e. excessive N appeared as nitrate in the leachate below the rooting zone. Reduction of atmospheric N emission and consequent atmospheric N deposition is proposed to be the only practical long-term solution to improve N-saturated forest ecosystems. However, responses of N-saturated forest ecosystems to reduced atmospheric N deposition have been seldom investigated. In the present study, atmospheric deposition was manipulated through roof constructions below the canopy of a mature Norway spruce forest on the Solling plateau in central Germany. A £^(5)N tracer field and a density fractionation laboratory experiment were conducted in the present study to investigate the influence of long-term reduced atmospheric N deposition on the partitioning of atmospheric N in different forest ecosystem compartments as well as on the partitioning of atmospheric N retained in the soil in different SOM pools.
We examined the influence of snow regime on subalpine ecosystem C and N cycling at Mount Rainier under ambient conditions and in climate change scenarios. Timing of snow release influenced ecosystem C and N storage and loss. Climate change may reduce snow accumulation by up to 80% at Mount Rainier by 2050. Snowpack loss may enhance ecosystem C and N accumulation during the growing season and increase winter N leaching.
Cold adaptation includes a complex range of structural and functional adaptations at the level of all cellular constituents, and these adaptations render cold-adapted organisms particularly useful for biotechnological applications. This book presents the most recent knowledge of (i) boundary conditions for microbial life in the cold, (ii) microbial diversity in various cold ecosystems, (iii) molecular cold adaptation mechanisms and (iv) the resulting biotechnological perspectives.
This book will provide a complete overview of an alpine ecosystem, based on the long-term research conducted at the Niwot Ridge LTER. There is, at present, no general book on alpine ecology. The alpine ecosystem features conditions near the limits of biological existence, and is a useful laboratory for asking more general ecological questions, because it offers large environmental change over relatively short distances. Factors such as macroclimate, microclimate, soil conditions, biota, and various biological factors change on differing scales, allowing insight into the relative contributions of the different factors on ecological outcomes.
Tundra ecosystems are seriously affected by global climate change. Understanding tundra history and post-glacial development may enhance the ability of biologists to anticipate biotic responses to current environmental changes. In this book, the authors analyse changes which have occurred in a vegetative cover and aboveground fauna of vertebrates at Yamal peninsula, one of the greatest plains on the globe. The authors also evaluate pedogenetic processes, soil nutrient status and plant distribution along an elevation gradient in the alpine tundra in the western Italian Alps. In addition, treeline ecotone is a belt of transition from forest vegetation to a non-forest one, which allow the monitoring of climate change. In this book, carbon deposition on the forests of two treeline ecotones is studied. Some of the current emerging theories, models and recent empirical evidence for the dynamics of these reciprocal interactions between climate and terrestrial microbial communities are also reviewed, with particular attention to biogeochemical and ecological perspectives.
