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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Restoration of Degraded Land: A comparison of Structural and Functional Measurements of Recovery

Heckman, John Richard 08 April 1997 (has links)
The main goals of this study were to document the structural and functional recovery of differently restored areas, to understand better the relationship between the two, and to determine which types of measurements are best for assessing restoration success. To address these questions, an experimental system was created through topsoil removal and subsequent restoration in a blocked, completely randomized design using two levels of soil amendment (with or without 10 kg of leaf mulch per m2) and three levels of seeding treatment (no seed, a standard reclamation mix, and an alternative, wildflower dominated reclamation mix). All measurements were designed to document responses due to restoration treatment in comparison to adjacent, undisturbed, reference sites. Vegetation structure in amended sites, as measured by total vegetation cover and species richness, recovered to levels similar to references within the two years of the study. Plant community composition did not develop similarity to references in any experimental treatments. Both soil amendment and seeding type affected cellulose decomposition rates, with amended plots showing higher decomposition rates than unamended, and seeded plots exhibiting higher rates than unseeded. Enzyme activities were largely determined by soil amendment, but the reference plots consistently had higher enzymatic activity. Amended sites exhibited significant increases over time in soil respiration, reaching or surpassing the rates observed in reference areas. Methane oxidation rates were generally increased in disturbed plots compared to undisturbed references due to increased atmospheric diffusion into the soil. Amended areas exhibited depressed rates relative to unamended, and seeding level had no significant effect on methane oxidation. Over all measurements, restoration of ecosystem function was most facilitated by the addition of the soil amendment. Seeding treatment significantly altered the resultant plant community, which may have substantial, long-term consequences for succession. The inclusion of functional parameters into restoration assessment provides for better overall information concerning ecosystem performance and may add to the ability to predict long-term success of restoration efforts. / Ph. D.
2

The Role of Geographic Information Systems in Post-Disaster Neighborhood Recovery: Lessons from Hurricanes Katrina and Rita

Baldwin, Brian 14 May 2010 (has links)
Through partnerships and collaborations with universities, non-profits, local government, and private foundations, neighborhood associations and residents have been using Public Participation Geographic Information Systems (PPGIS) as a tool for neighborhood recovery in post-Katrina and Rita New Orleans. The landfall of Hurricanes Katrina and Rita along the Gulf Coast Region changed the way that Geographic Information Systems (GIS) are used for Emergency Management and Response, PPGIS, and community recovery. This research explores GIS and PPGIS best practices through an evaluation of New Orleans, LA case studies and seeks to present solutions for the development of a post-disaster PPGIS for community recovery.
3

Invertebrate community reassembly and altered ecosystem process rates following experimental habitat restoration in a mined peat bog in New Zealand

Watts, Corinne Hannah January 2006 (has links)
I investigated the effects ofhabitat loss and subsequent restoration on invertebrate community structure and ecosystem functioning in a mined peat bog in the North Island, New Zealand. In an experimental trial, the impact of peat bog habitat loss and isolation on the invertebrate community associated with Sporadanthus ferrugineus (Restionaceae) was investigated. Potted S. ferrugineus plants were exposed to invertebrates at various distances up to 800 m from an intact habitat (the presumed source population) over 18 weeks. Invertebrates rapidly colonised the experimental plants, with all major Orders and trophic groups present on Sc ferrugineus within 6 weeks. However. with increasing distance away from the undisturbed habitat, there was a significant decrease in total richness and abundance of invertebrates associated with the potted plants. Additional tests showed that even a moderate degree of isolation (i.e. greater than 400 m) from the intact habitat caused an almost complete failure of 'Batrachedra' sp. to colonise its host plant, at least in the short-term, The density of eggs and larvae, and the average larval size of 'Batrachedra' sp. (Lepidoptera: Coleophoridae) colonising Si ferrugineus plants, as well as the proportion of Si ferrugineus stems damaged by 'Batrachedra' sp. herbivory, all decreased logarithmically with increasing distance from the intact habitat. Surprisingly, though, the rate of recovery of the insect-plant interaction following experimental habitat restoration was remarkably rapid (i.e. between 3Y2 and 6 years). After just 6 years there was no significant difference in insect-plant interactions between the intact peat bog sites and any of the experimentally restored sites up to 800 m away. These results suggest that the degree of isolation from undisturbed habitat has a major impact on the rate and patterns of restoration recovery in the invertebrate community and that some insect-plant interactions can recover rapidly from habitat loss with restoration management. Restoration of mined peat bogs in northern New Zealand is initiated by establishing a native vegetation cover to minimize further peat degradation. The effects of various restoration techniques on litter decomposition, microbial community activity and beetle community composition were investigated within an experimental trial, These treatments included translocation ofpeat bog habitat (direct transfer of islands), milled peat islands with no seed and milled peat islands with seed, and were compared with an unrestored mined site and an undisturbed peat bog. In all the response variables measured, the undisturbed peat bog sites had significantly higher decomposition rates and microbial respiration rates, and significantly higher abundance and species richness of beetles than any of the restoration treatments. Inaddition, the technique used to restore mined peatlands had a significant effect on the beetle community composition and litter decomposition processes. Despite a rapid initial change in the beetle community following habitat translocation, the direct transfer islands were still the most similar in beetle species composition to the undisturbed peat bog. Microbial activity and decomposition rates were higher in the direct transfer and mined peat surface after 6 months. However, even after 12 months, decomposition rates in the restored habitats were still far from reaching the levels recorded in the undisturbed peat bog. The results suggest that beetle community structure and ecosystem processes such as decomposition and microbial activity rates may be able to recover faster with certain restoration techniques, such as direct transfer of intact habitat islands. Subsequently, I examined long-term beetle community reassembly on islands that had been restored by creating raised areas ofprocessed peat with the addition of Leptospermum scoparium seed. Monitoring of different-aged restored islands representing the full range of restoration ages (up to 6 years) available at the peat mine, indicated that as the peat islands became older and the vegetation structure became more complex, the abundance, species richness and composition of the beetle community became increasingly similar to the community in the undisturbed peat bog. Despite this, distinct differences between the intact peat bog and older restored peat islands still persisted, even after 6 years, particularly at an individual species level. However, it is predicted that within 12 years the restored peat islands will share 100% ofbeetle species in common with the undisturbed peat bog. Taken together, these results indicate that restoration is effective in initiating the recovery of beetle assemblages and ecosystem processes (such as litter decomposition and microbial community activity) in cut-over peat bogs. However, it is estimated to take at least 12 years before pre-mining communities and functions are attained, and ongoing monitoring to develop an understanding of the longer-term dynamics of such ecosystems and processes is clearly required.
4

Invertebrate community reassembly and altered ecosystem process rates following experimental habitat restoration in a mined peat bog in New Zealand

Watts, Corinne Hannah January 2006 (has links)
I investigated the effects ofhabitat loss and subsequent restoration on invertebrate community structure and ecosystem functioning in a mined peat bog in the North Island, New Zealand. In an experimental trial, the impact of peat bog habitat loss and isolation on the invertebrate community associated with Sporadanthus ferrugineus (Restionaceae) was investigated. Potted S. ferrugineus plants were exposed to invertebrates at various distances up to 800 m from an intact habitat (the presumed source population) over 18 weeks. Invertebrates rapidly colonised the experimental plants, with all major Orders and trophic groups present on Sc ferrugineus within 6 weeks. However. with increasing distance away from the undisturbed habitat, there was a significant decrease in total richness and abundance of invertebrates associated with the potted plants. Additional tests showed that even a moderate degree of isolation (i.e. greater than 400 m) from the intact habitat caused an almost complete failure of 'Batrachedra' sp. to colonise its host plant, at least in the short-term, The density of eggs and larvae, and the average larval size of 'Batrachedra' sp. (Lepidoptera: Coleophoridae) colonising Si ferrugineus plants, as well as the proportion of Si ferrugineus stems damaged by 'Batrachedra' sp. herbivory, all decreased logarithmically with increasing distance from the intact habitat. Surprisingly, though, the rate of recovery of the insect-plant interaction following experimental habitat restoration was remarkably rapid (i.e. between 3Y2 and 6 years). After just 6 years there was no significant difference in insect-plant interactions between the intact peat bog sites and any of the experimentally restored sites up to 800 m away. These results suggest that the degree of isolation from undisturbed habitat has a major impact on the rate and patterns of restoration recovery in the invertebrate community and that some insect-plant interactions can recover rapidly from habitat loss with restoration management. Restoration of mined peat bogs in northern New Zealand is initiated by establishing a native vegetation cover to minimize further peat degradation. The effects of various restoration techniques on litter decomposition, microbial community activity and beetle community composition were investigated within an experimental trial, These treatments included translocation ofpeat bog habitat (direct transfer of islands), milled peat islands with no seed and milled peat islands with seed, and were compared with an unrestored mined site and an undisturbed peat bog. In all the response variables measured, the undisturbed peat bog sites had significantly higher decomposition rates and microbial respiration rates, and significantly higher abundance and species richness of beetles than any of the restoration treatments. Inaddition, the technique used to restore mined peatlands had a significant effect on the beetle community composition and litter decomposition processes. Despite a rapid initial change in the beetle community following habitat translocation, the direct transfer islands were still the most similar in beetle species composition to the undisturbed peat bog. Microbial activity and decomposition rates were higher in the direct transfer and mined peat surface after 6 months. However, even after 12 months, decomposition rates in the restored habitats were still far from reaching the levels recorded in the undisturbed peat bog. The results suggest that beetle community structure and ecosystem processes such as decomposition and microbial activity rates may be able to recover faster with certain restoration techniques, such as direct transfer of intact habitat islands. Subsequently, I examined long-term beetle community reassembly on islands that had been restored by creating raised areas ofprocessed peat with the addition of Leptospermum scoparium seed. Monitoring of different-aged restored islands representing the full range of restoration ages (up to 6 years) available at the peat mine, indicated that as the peat islands became older and the vegetation structure became more complex, the abundance, species richness and composition of the beetle community became increasingly similar to the community in the undisturbed peat bog. Despite this, distinct differences between the intact peat bog and older restored peat islands still persisted, even after 6 years, particularly at an individual species level. However, it is predicted that within 12 years the restored peat islands will share 100% ofbeetle species in common with the undisturbed peat bog. Taken together, these results indicate that restoration is effective in initiating the recovery of beetle assemblages and ecosystem processes (such as litter decomposition and microbial community activity) in cut-over peat bogs. However, it is estimated to take at least 12 years before pre-mining communities and functions are attained, and ongoing monitoring to develop an understanding of the longer-term dynamics of such ecosystems and processes is clearly required.

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