Browsing by Subject "Wood"
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Item Assessing the woody biomass supply chain in the Pacific Northwest and Great Lakes regions: Investigating policy as drivers of change(2015-08) Kudrna, JordanWith the ever-increasing need for clean and accessible energy sources, woody biomass has long been entertained as a potential prospect. As energy markets and business operations are influenced by political decisions, it is essential to know the relationship between policy impacts on business innovation and investment decisions. This study looks at significant changes woody biomass business owners have implemented over the course of their operations, and how state and federal policies have affected those changes. A survey of 175 woody biomass business owners in the upper Midwest Lake States and Pacific Northwest was conducted in 2014 to gain insight into the bioenergy investment decisions of logging and transport businesses, utility companies, pellet and densified fuel producers, and institutional heat users. Failing to understand policy influence on business innovation risks investment in ineffective strategies and business uncertainty. The results of this study will help arm policy makers and energy professionals with knowledge about how current renewable energy policies are influencing business investment decisions along the wood-energy supply chain in hopes of more effective policy planning and implementation.Item Channel, Riparian and Catchment Features as Predictors of Wood Abundance in Low Gradient, Agricultural Streams(University of Minnesota Duluth, 2002) Johnson, Lucinda B; Host, George E; Richards, CarlWood is an important component of small to medium streams in forested regions, but has been little studied in agricultural areas. Although wood habitat has been shown to be an important factor controlling macroinvertebrate biodiversity in agricultural regions of the Midwestern U.S., there is little information on how much wood is available and what factors control its abundance and distribution. The goals of this study were to: 1) characterize the abundance, size, and distribution of wood in low gradient streams in a predominantly agricultural region, and 2) quantify the relative influence of reach- and catchment-scale factors on the abundance and distribution of wood in these streams. Standing stocks of wood were quantified in 49 stream reaches in the Saginaw Basin of central Michigan, USA. An array of stream channel, riparian zone, and catchment features were quantified. Multiple regressions were conducted to predict standing stocks from explanatory variables at three spatial scales. Features at the local scale (e.g., bank-full width, % open canopy) had a large influence on the density and size of accumulations, and a moderate influence on wood abundance. In contrast, riparian and catchment features including riparian vegetation type, link number, % urban land use in the catchment, and topographic heterogeneity exerted greater control over wood abundance and the mean size of wood accumulations. The differences in the factors predicting wood standing stocks versus accumulation density are probably related to the presence of structures that entrain wood into accumulations. In contrast, wood standing stocks reflect current and past land use practices, as well as underlying processes (e.g., hydrologic regime) controlled by landforms. Patterns in wood standing stock and distribution differ from those observed in high gradient regions, and low gradient streams in forested regions. This has important implications for ecosystem processes and management of headwater streams in agricultural regions.Item Fungi in Antarctica: a circumpolar study of biodiversity in soils and historic structures.(2010-07) Arenz, Brett EvanAntarctica is the most remote and isolated continent on Earth and is generally thought to have low biodiversity due to environmental extremes. These relatively simple ecosystems are important to study because they can be used to improve understanding of more complex systems world-wide that are difficult to analyze directly. The isolation of the continent, extreme environmental conditions and the lack of functional redundancy in ecosystem processes make it particularly vulnerable to human disturbance and require improved understanding. The results of this research support the hypothesis that fungal abundance and distribution are generally linked to the presence of primary producers and their effect on carbon and nitrogen quantities in the soil. Experiments introducing sterile plant-derived nutrient sources (wood and cellulose) to soils resulted in increased fungal abundance up to three to four orders of magnitude greater than background soil levels. This suggests that the extremes of the Antarctic environment (low moisture, high salinity, cold temperatures) are primarily affecting fungi by limiting the distribution of flora and direct effects on the fungi are relatively less important as these indigenous soil fungi appear well adapted to Antarctic environment. A survey of fungal diversity near historic sites and areas where materials were introduced to the Antarctic Peninsula reveals a very similar composition to those affecting historic sites on Ross Island. The fungi found in greatest abundance were species of Geomyces and Cadophora. These two genera also formed a large percentage of the fungal colonization of buried nutrient substrates. The frequent reports of these fungi from many areas in Antarctica and the large diversity of species found indicates they are well adapted to their environment and suggests they are indigenous to Antarctica. The dominance of these fungi on human-introduced material indicates direct human influences may be of more benefit to generalist indigenous decomposer fungi which are pre-adapted to the environmental extremes rather than human-introduced fungi which may be better adapted to utilizing these substrates but not well adapted to the Antarctic environment. It also supports the hypothesis of indigenous Antarctic fungi being primarily limited by nutrient availability.Item Instream wood transport, and effects of forest harvest on geomorphology and fish, in northern Minnesota streams.(2009-06) Merten, Eric ChristopherTrees provide critical functions to the ecology of streams. Trees affect hydrology, mitigate sediment inputs, and buffer water temperatures by providing shade. Watersheds with a higher proportion of mature forest tend to have less variable hydrographs, and older trees provide larger pieces of wood to streams. Instream wood itself affects nearly every process in stream ecology. Despite their ecological importance, trees and instream wood have been greatly modified by humans. The studies described in this dissertation advance current knowledge as follows: We demonstrate that headwater streams in northern forests can require ten years to recover from a large input of fine sediment, depending on the occurrence of stormflows. Our analyses suggest that, at the basin scale, warmer air temperatures in summer are more important to the abundances of some headwater fish species than instream habitat or spring precipitation. The analyses also lend support to previous findings that riparian forest harvest can cause local stream warming. Wood transport in streams is a dynamic process. Forty-one percent of over 800 wood pieces were mobilized (at least 10m) during a study period by a single high flow event. Thirty-two percent of the mobilized pieces became entrapped again before leaving their study reach. Mobilization of wood in streams is a complex function of both mechanical and hydraulic factors. Eleven potential predictor variables were studied, and seven were identified as significant to wood mobilization using multiple logistic regression. The seven predictors were burial, effective depth, length ratio, bracing, rootwad presence, downstream force ratio, and draft ratio. Entrapment of wood in streams is related primarily to the length ratio and weight of the wood pieces. The mechanisms for entrapment are not always clear; wood pieces may simply be entrapped wherever they are located when high water recedes. Together, this dissertation suggests that forest harvest should avoid excess sediment inputs (due to persistence) and stream warming (due to effects on fish). It also develops models that can be used for more informed management of instream wood. Stream managers and restorers can apply the results presented to reverse the impacts of historic logging and wood removal on streams.