Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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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 Using successional theory to guide restoration of invasive plant dominated rangeland(Montana State University - Bozeman, College of Agriculture, 2003) Anderson, Jennifer Lisa; Chairperson, Graduate Committee: Douglas J. Dollhopf.Item Directing succession by altering nutrient availability(Montana State University - Bozeman, College of Agriculture, 1999) Herron, Gretchen J.Item Using ecological theory to guide the implementation of augmentative restoration(Montana State University - Bozeman, College of Agriculture, 2004) Bard, Erin Christina; Co-chairs, Graduate Committee: Roger L. Sheley and Jeff JacobsenInvasive organisms are now considered the second worst threat to native biological biodiversity, behind habitat loss and fragmentation. Successful control of invasive plants can have unexpected impacts on native plants and wildland systems. Therefore, it is important for managers of invasive species to become increasingly concerned with more than target invaders, but also ecological mechanisms and processes like invasion resistance, environmental heterogeneity, and succession that direct plant community dynamics. Augmentative restoration is a management approach that augments existing ecological processes by selectively repairing and replacing those processes that are damaged or missing thereby directing plant communities in a desirable direction. Our overall objective was to test the concept of augmentative restoration. Our overall hypothesis was that successional processes occurring at high levels could be augmented by selectively repairing or replacing successional processes that occur at low levels to increase desired species composition. In a split plot design with 4 replications at 3 sites, 8 factorial treatment combinations from 3 factors (shallow tilling, watering, and seeding) were applied to whole plots, and 2,4-D was applied to sub plots. Cover and density of seeded species, Centaurea maculosa, and Potentilla recta as well as existing native and exotic forbs and grasses were sampled in 2002 and 2003 to produce pretreatment and post-treatment data. ANCOVA was used to analyze cover and density data using pre-treatment data as a baseline covariate. Data indicated that areas with high percent bare ground required seeding and watering to increase seeded species and native forbs, while seeding and tilling increased seeded species and native forbs in areas of high soil moisture. C. maculosa, P. recta, and exotic forbs decreased in response to tilling and 2,4-D. Exotic and native grasses increased in response to tilling and 2,4-D indicating that grasses may have reproduced primarily vegetatively. This data provided evidence that augmentative restoration could provide managers with an ecological framework to develop restoration procedures that address invasion resistance, environmental heterogeneity, and succession in order to enhance native forbs and grasses as well as improve the emergence of seeded species to increase desired plant composition in wildlands damaged by invasive plants.