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.

Standardized methods and measurements are crucial for ecological research, particularly in long-term ecological studies where the projects are by nature collaborative and where it can be difficult to distinguish signs of environmental change from the effects of differing methodologies. This second volume in the Long-Term Ecological Research (LTER) Network Series addresses these issues directly by providing a comprehensive standardized set of protocols for measuring soil properties. The goal of the volume is to facilitate cross-site synthesis and evaluation of ecosystem processes. Chapters cover methods for studying physical and chemical properties of soils, soil biological properties, and soil organisms, and they include work from many leaders in the field. The book is the first broadly based compendium of standardized soil measurement methods and will be an invaluable resource for ecologists, agronomists, and soil scientists.

The hyporheic zone is the area just below a river where constant mixing of groundwater and river water occurs. At this intersection between two sources of water, with different organic carbon and nutrient contents, complimentary pairing of electron donors and acceptors occurs, causing elevated rates of microbial metabolism. Due to these constant changes in electron acceptor and donor availability and because of microbial oxygen consumption dynamics, redox cycling process are constantly occurring and changing within the hyporheic zone. Iron oxides are theorized to play an important role in protecting sediment organic carbon from microbial metabolism through the formation of organo-metal aggregates. This thesis document outlines three related experiments investigating how different sources and forms of organic carbon found in freshwater river and groundwater systems effects hyporheic zone microbial metabolism rates. These studies revealed that deposition of autochthonous and allochthonous organic carbon to the riverbed sediment matrix (i.e. hyporheic zone) was correlated with release of labile dissolved organic carbon. Photosynthetic periphyton biomass (i.e. autochthonous epilithic biomass) was identified as a key source of organic carbon, which lead to highly elevated rates of aerobic respiration, anaerobic respiration, and methanogenesis. The presence of small pockets of anaerobic respiration and methanogenesis was observed within predominantly aerobic metabolizing sediment batch reactors; this shows that hyporheic zone sediment microbial community structure is highly heterogenous with patches of flexible metabolism occurring, depending on electron donor/acceptor availability. Iron bound organic carbon content was correlated with the presence of reactive iron oxide minerals, and these organo-metal aggregates were not biodegraded due to preferential metabolism of more labile pools of carbon such as fresh periphyton POM and DOC. The increase in microbial activity associated with fresh periphyton biomass deposition shows that in freshwater river systems periphyton biomass is a major contributor to ecosystem respiration as well as gross primary productivity. Understanding how natural and anthropogenic inputs of organic carbon, nitrogen, phosphorous and sulfate cause changes in periphyton growth and hence changes in hyporheic zone microbial metabolism is on ongoing challenge to modeling the global carbon cycle.

In terrestrial ecosystems, soil microorganisms and soil animals are essential for litter degradation, soil formation and the availability of nutrients and trace elements. The measurement of biological soil parameters allows a rapid evaluation of the effects of chemical and physical influences due to pollutants or soil management. This book introduces a number of well proved methods for the analysis of carbon, nitrogen, phosphorus and sulfur cycles. It focuses further on the determination of the number and biomass of microorganisms, algae and animals in the soil. Particular emphasis is placed on the comprehensible and complete description of the experimental procedures.

Understanding the effects climate change will have on the structure and function of global ecosystems is a pressing ecological and social issue. Global change driven changes in atmospheric warming and precipitation régimes have begun to alter the distribution of plants and animals in, as well as the function of, ecosystems. Using two large-scale climate change manipulations, I assessed the effect of changing precipitation and temperature regimes on soil microbial community structure and function. Soil microbial communities regulate decomposition and nutrient cycling rates in ecosystems, thus understanding their response to climatic changes will enable scientists to better predict carbon feedbacks to the atmosphere as well as functional shifts within ecosystems. My first two chapters took advantage of a large-scale precipitation manipulation in a semi-arid woodland. My first chapter aimed to understand how changing precipitation amounts altered the structure and abundance of soil bacteria and fungi; while my second chapter measured how changing precipitation altered soil nitrogen cycling. Overall, I found that soil microbial community composition and function were responsive to changes in precipitation, but these responses were contingent upon seasonal variability in precipitation and the aboveground plant community. My final experiment examined how changing temperature altered soil microbial community structure and function in two temperate forests. Using a large scale warming experiment at two locations, I examined how changes in temperature altered microbial composition, abundance, potential enzyme activity, and decomposition. I found that the effects of warming were contingent upon location; microbial community composition responded to alterations in soil temperature and soil moisture at the warmer site, but not at the cooler site. Unexpectedly, the change in microbial community composition did not result in changes in the rate of decomposition. I conclude that the soil is relatively buffered from atmospheric warming thus changes in microbial community structure and function may take longer than a few years to develop. Taken together, my research demonstrates that understanding the effects of climate change on microbial community structure and function is complex and contingent upon the background abiotic and biotic variability within an ecosystem.

The causes and consequences of differences in microbial community structure, defined here as the relative proportions of rare and abundant organisms within a community, are poorly understood. Articles in “The Causes and Consequences of Microbial Community Structure”, use empirical or modeling approaches as well as literature reviews to enrich our mechanistic understanding of the controls over the relationship between community structure and ecosystem processes. Specifically, authors address the role of trait distributions and tradeoffs, species-species interactions, evolutionary dynamics, community assembly processes and physical controls in affecting ‘who’s there’ and ‘what they are doing.’