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Fish Distributions And Nutrient Cycling In Streams: Can Fish Create Biogeochemical Hotspots, Peter B. Mcintyre, Alexander S. Flecker, Michael J. Vanni, James M. Hood, Brad W. Taylor, Steven A. Thomas Aug 2008

Fish Distributions And Nutrient Cycling In Streams: Can Fish Create Biogeochemical Hotspots, Peter B. Mcintyre, Alexander S. Flecker, Michael J. Vanni, James M. Hood, Brad W. Taylor, Steven A. Thomas

Dartmouth Scholarship

Rates of biogeochemical processes often vary widely in space and time, and characterizing this variation is critical for understanding ecosystem functioning. In streams, spatial hotspots of nutrient transformations are generally attributed to physical and microbial processes. Here we examine the potential for heterogeneous distributions of fish to generate hotspots of nutrient recycling. We measured nitrogen (N) and phosphorus (P) excretion rates of 47 species of fish in an N-limited Neotropical stream, and we combined these data with population densities in each of 49 stream channel units to estimate unit- and reach-scale nutrient recycling. Species varied widely in rates of N …


New And Current Microbiological Tools For Ecosystem Ecologists: Towards A Goal Of Linking Structure And Function, Rebecca E. Drenovsky, Kevin P. Ferris, Katharine M. Batten, Krassimira Hristova Jan 2008

New And Current Microbiological Tools For Ecosystem Ecologists: Towards A Goal Of Linking Structure And Function, Rebecca E. Drenovsky, Kevin P. Ferris, Katharine M. Batten, Krassimira Hristova

Biology

Interest in the relationships between soil microbial communities and ecosystem functions is growing with increasing recognition of the key roles microorganisms play in a variety of ecosystems. With a wealth of microbial methods now available, selecting the most appropriate method can be daunting, especially to those new to the field of microbial ecology. In this review, we highlight those methods currently used and most applicable to ecological studies, including assays to study various aspects of the carbon and nitrogen cycles (e.g., pool dilution, acetylene reduction, enzyme analyses, among others), methods to assess microbial community composition (e.g., phospholipid fatty acid analysis …


Influence Of Pocket Gopher Mounds On Nonnative Plant Establishment In A Shrubsteppe Ecosystem, G. P. Kyle, Andrew Kulmatiski, Karen H. Beard Jan 2008

Influence Of Pocket Gopher Mounds On Nonnative Plant Establishment In A Shrubsteppe Ecosystem, G. P. Kyle, Andrew Kulmatiski, Karen H. Beard

Wildland Resources Faculty Publications

Soil disturbances across a wide range of spatial scales have been found to promote the establishment of invasive plant species. This study addresses whether mounds built by northern pocket gophers (Thomomys talpoides) in the shrubsteppe environment of north central Washington are facilitating plant invasions into native-dominated fields. Research was conducted in native-dominated plant communities adjacent to ex-arable, nonnative-dominated fields. To determine the effect of mounds on plant growth, we recorded new establishment and persistence of all plant species over 2 growing seasons on 10–19 mound and intermound areas in 10 fields. Nonnative plant establishment was not affected by mounds, but …