Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
7 results
Search Results
Item Understanding the effects of floodplain shade on hyporheic and stream channel temperature cycles(Montana State University - Bozeman, College of Agriculture, 2024) Fogg, Sarah Kathleen; Chairperson, Graduate Committee: Geoffrey C. Poole; This is a manuscript style paper that includes co-authored chapters.River reaches with coarse-grained alluvial floodplains have a breadth of lateral interaction between the channel and surrounding landscape, yielding extensive riparian zones and high rates of gross water exchange between the channel and substrate (i.e., hyporheic exchange). The lateral hyporheic zone on floodplain rivers is often near the ground surface, allowing for heat exchange between the atmosphere, unsaturated sediments, and hyporheic zone. We hypothesized that floodplain shade overlying lateral hyporheic water influences the conductive heat flux through unsaturated sediments, thus influencing hyporheic temperatures and temperatures in associated stream channels. We conducted simulation modeling experiments to test the potential effects of floodplain shade on hyporheic and stream channel temperatures. We found that scenarios with floodplain shade led to cooler hyporheic and stream temperatures than scenarios lacking floodplain shade under a variety of realistic floodplain conditions. We conclude that floodplain forest shade is a novel consideration for riparian management on floodplain river reaches and may be crucial in managing and maintaining cold-water habitat into the future.Item Scaling nitrogen retention from trees to forests through succession(Montana State University - Bozeman, College of Agriculture, 2016) Scott-Klingborg, Aaron James; Chairperson, Graduate Committee: Jack Brookshire; Jack Brookshire was an author of the article, 'Large trees dominate nitrogen retention across forest succession' submitted to the journal 'Ecology letters' which is contained within this thesis.; Jack Brookshire was an author of the article, 'Expression of sink-driven and transactional nitrogen limitation following stand-replacing disturbance in an inland pacific northwest coniferous forest' submitted to the journal 'Ecosystems' which is contained within this thesis.We seek to understand how the ability of trees to acquire and retain nitrogen (N) changes throughout their lifetimes. This capacity enables trees to act as carbon (C) sinks individually and collectively in forest ecosystems over successional time scales. We evaluate how properties that govern nutrient retention change with tree size and forest age, and how allometric relationships scale up to influence ecosystem-level patterns of N cycling and retention. Most generally, we hypothesized that changes in N uptake and recycling efficiency with increasing tree size would vary with forest age and N availability. Additionally, we evaluated changes in ecosystem-level C and N accumulation throughout secondary forest succession following clear-cut logging disturbances in an effort to understand how N limitation may become expressed over time and interact with forest successional dynamics. Our findings highlight the importance of large trees in ecosystem N cycling and growth. We find that increasing mass growth rates are matched by an increasing capacity to acquire and retain N without necessitating increases in growth efficiency. Research findings indicate that mortality of single trees may hold profound consequences for stand-level N retention in addition to C storage. At the ecosystem scale, we find N accumulation and limitation are dynamic processes that fluctuate in strength and source over forest succession, and that ecosystem accumulation of N was driven predominately by increasing N in plant biomass rather than in soil pools.Item Soil temperature and soil moisture characteristics for several habitat types of Montana and Idaho(Montana State University - Bozeman, College of Agriculture, 1996) Sirucek, DeanItem Influence of lodgepole pine spacing intervals and herbicide treatment on soil characteristics(Montana State University - Bozeman, College of Agriculture, 1997) Hagler, Steven EugeneItem Determinants of fire regime variability in lower elevation forests of the northern Greater Yellowstone Ecosystem(Montana State University - Bozeman, College of Agriculture, 2002) Littell, Jeremy ScottItem Amorphous character in twenty western Montana forest soils with apparent eolian influence(Montana State University - Bozeman, College of Agriculture, 1977) Ottersberg, Robert JosephItem Biological and physical controls of CO 2 flux through snow in a forested ecosystem(Montana State University - Bozeman, College of Agriculture, 2013) Rains, Fredrick Aaron; Chairperson, Graduate Committee: Paul C. Stoy; Cliff Montagne (co-chair)Soil CO 2 efflux is the dominant component of carbon loss in many temperate forests. Wintertime respiration accounts for a significant contribution of the annual carbon loss to the atmosphere from terrestrial ecosystems, but the magnitude of this flux and physical transport mechanisms through snow are unclear. This research examines wintertime CO 2 flux in a lodgepole pine forest in the Upper Stringer Creek catchment at the Tenderfoot Creek Experimental Forest, Montana, USA. I hypothesized that: CO 2 production and efflux during the winter contributes a significant amount (10-20%)of CO 2 efflux to the atmosphere in the Tenderfoot Creek Experimental Forest; 2) Snow properties, i.e. depth and density, and thereby porosity and tortuosity vary during the winter via snow metamorphosis, thus changing the impediment to flux through the snow medium and CO 2 production increases when the snowpack becomes isothermal during melt due to increased soil moisture and soil temperature. A micrometeorological stations was installed to measure soil water content, soil temperature, incoming and outgoing radiation, albedo, snow depth, snow/soil interface CO 2 concentration, atmospheric CO 2 concentration, three-dimensional wind speed, and above snow/sub-canopy CO 2 flux on a half-hourly basis. In addition, throughout the winters of 2010/2011 and 2011/2012 snow pit analyses was performed in triplicate approximately once monthly and snow depth, density, and temperature were measured in 10-centimeter increments. Three methodological approaches were used to analyze CO 2 flux through the snow pack: Chamber on snow, two-point Fick's law based diffusivity modeling, and snow-surface/subcanopy eddy covariance. The results of the comparison show a significant difference in measured and estimated flux between methodologies during early and late winter, while demonstrating the Fick's based model is can accurately estimate up 75% of measured flux during mid-winter. Observations are consistent with advection, in addition to diffusion, as a mechanism of CO 2 transport through snow such that observation strategies that do not account for advection may underestimate wintertime efflux. Furthermore, all three methodologies indicate that wintertime respiration is a major contributor to the annual carbon budget when mean flux rates are compared to growing season flux rates.