Physical Sciences and Mathematics Commons^™

Nitrogen Fixation Rates In Forested Mountain Streams: Are Sediment Microbes More Important Than Previously Thought?, Erica A. H. Bakker, Carmella Vizza, Clay Arango, Sarah S. Roley

Biology Faculty Scholarship

1. Biological nitrogen (N) fixation, the microbial conversion of N₂ gas to ammonia, makes N available to food webs. Low-N streams often have a high relative abundance of N-fixing taxa, suggesting that N fixation is an important N source in these systems. Despite this potential, stream N fixation has not been well-characterised, particularly compared to lakes and marine environments. One unknown is the relative contributions of various N-fixing organisms, particularly heterotrophic microbes.
2. In low-N streams in the Cascade Mountains (Washington, USA), three groups of N-fixers predominate: cyanobacteria (Nostoc paramelioides) colonies that house a midge symbiont (Cricotopus spp.), …

Habitat Characteristics Or Protected Area Size: What Is More Important For The Composition And Diversity Of Mammals In Nonprotected Areas?, Wenbo Li, Jinhua Li, Peipei Yang, Bowen Li, Chao Liu, Lixing Sun

Biology Faculty Scholarship

The margins of protected areas are usually considered to have greater forest degradation, and given that most mammals live outside protected areas, researchers and conservation practitioners are increasingly recognizing that nonprotected areas must be incorporated into conservation strategy. However, the strategy used to manage these areas still involves increasing the size of protected areas, while not considering the habitat characteristics and requirements of the species. In this study, during a 3-year period, camera trap and habitat characteristic surveys were used to estimate composition, diversity, and habitat characteristics of mammals to determine habitat characteristics or increase the size of protected areas …

Dynamic Microclimate Boundaries Across A Sharp Tropical Rainforest–Clearing Edge, Eric A. Graham, Mark Hansen, William J. Kaiser, Yeung Lam, Eric Yuen, Philip W. Rundel

Biology Faculty Scholarship

As landscapes become increasingly fragmented, research into impacts from disturbance and how edges affect vegetation and community structure has become more important. Descriptive studies on how microclimate changes across sharp transition zones have long existed in the literature and recently more attention has been focused on understanding the dynamic patterns of microclimate associated with forest edges. Increasing concern about forest fragmentation has led to new technologies for modeling forest microclimates. However, forest boundaries pose important challenges to not only microclimate modeling but also sampling regimes in order to capture the diurnal and seasonal dynamic aspects of microclimate along forest edges. …

Complex Interactive Effects Of Water Mold, Herbicide, And The Fungus Batrachochytrium Dendrobatidis On Pacific Treefrog Hyliola Regilla Hosts, John M. Romansic, James E. Johnson, R. Steven Wagner, Rebecca H. Hill, Christopher A. Gaulke, Vance T. Vredenburg, Andrew R. Blaustein

Biology Faculty Scholarship

Infectious diseases pose a serious threat to global biodiversity. However, their ecological impacts are not independent of environmental conditions. For example, the pathogenic fungus Batrachochytrium dendrobatidis (Bd), which has contributed to population declines and extinctions in many amphibian species, interacts with several environmental factors to influence its hosts, but potential interactions with other pathogens and environmental contaminants are understudied. We examined the combined effects of Bd, a water mold (Achlya sp.), and the herbicide Roundup® Regular (hereafter, Roundup®) on larval Pacific treefrog Hyliola regilla hosts. We employed a 2 wk, fully factorial laboratory experiment with 3 …

Continuous Monitoring Reveals Multiple Controls On Ecosystem Metabolism In A Suburban Stream, Jake J. Beaulieu, Clay P. Arango, David A. Balz, William D. Shuster

Biology Faculty Scholarship

1. Primary production and respiration in streams, collectively referred to as stream ecosystem metabolism, are fundamental processes that determine trophic structure, biomass and nutrient cycling. Few studies have used high‐frequency measurements of gross primary production (GPP) and ecosystem respiration (ER) over extended periods to characterise the factors that control stream ecosystem metabolism at hourly, daily, seasonal and annual scales.

2. We measured ecosystem metabolism at 5‐min intervals for 23 months in Shepherd Creek, a small suburban stream in Cincinnati, Ohio (U.S.A.).

3. Daily GPP was best predicted by a model containing light and its synergistic interaction with water temperature. Water …

Seed Invasion Filters And Forest Fire Severity, Tom R. Cottrell, Paul F. Hessburg, Jonathan A. Betz

Biology Faculty Scholarship

Forest seed dispersal is altered after fire. Using seed traps, we studied impacts of fire severity on timing of seed dispersal, total seed rain, and seed rain richness in patches of high and low severity fire and unburned Douglas-fir (Pseudotsuga menziesii) forests in the Fischer and Tyee fire complexes in the eastern Washington Cascades. Unburned plots had the lowest average seed production. The high severity fire patches in the Fischer Fire Complex had a higher total seed production than low severity fire patches of the same complex. At the Tyee Fire Complex, the total seed production for each …