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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

The agricultural and forestry land-use of Szechuan basin ...

Hu, Chiao-ju, January 1946 (has links)
Thesis (Ph. D.)--University of Chicago, 1942. / Folded plates and maps in pocket. "A selected bibliography": p. 144-157.
2

Towards a farming systems approach to tree nut research in Malawi /

Hancock, Wayne Mitchell. January 1992 (has links)
Thesis (MSc. (Honours))--University of Western Sydney, Hawkesbury, 1992. / "Thesis submitted for the Award of Master of Science (Hons) from the University of Western Sydney Hawkesbury 1992."
3

Die entwicklung und das verhältnis von wald und kulturboden in der grafschaft Glatz ...

Stache, Günter Willi, January 1937 (has links)
Inaug.-diss.--Greifswald. / Lebenslauf. "Literatur": p. 58-63.
4

Wiregrass the transformation of southeast Alabama, 1880-1930 /

Byrd, William N., Biggs, Lindy, January 2009 (has links)
Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references (p. 231-245).
5

A systematic approach for using lidar intensity to detect forest structure.

Langford, Jaden Orion 12 November 2008 (has links)
Lidar intensity, a quantity analogous to backscatter, has yet to be fully exploited as an information source in the characterization of coniferous forests. Intensity images appear noisy due to (1) dynamic survey geometry, and (2) complex laser interactions in a forested environment. The nature of these issues are explored, and a systematic procedure for processing, visualizing, and normalizing the intensity data is presented. Despite high variability among neighbouring intensity values, the data are inherently spatially structured. Results from an investigation into the spatial pattern of intensity demonstrate that (1) the scale and variability of global estimates of spatial autocorrelation derived from raw intensity (point) data were markedly different between stands of different age, and these differences were driven by the canopy and gap structure within each individual stand, and (2) the magnitude of local estimates of spatial autocorrelation varied with canopy height, and, particularly in old growth stands, these magnitudes are linked to compositional factors such as species.
6

Kvarboende vid vägs ände : människors försörjning i det inre av södra Norrland under svensk efterkrigstid /

Lagerqvist, Christopher, January 2008 (has links)
Thesis (doctoral)--Uppsala University, 2008. / Includes bibliographical references (p. 208-214).
7

Working through conflict: two examples of agreement in community forests

Corrigan, Joselin 26 October 2009 (has links)
Developing a community forest in British Columbia involves multiple stakeholder agreements; negotiating agreement within diverse communities can be especially complicated. In this study I use the constant comparative method from grounded theory to compare data from two case studies and examine the conflict resolution techniques used by community forest developers throughout their development initiatives. Data were collected through interviews with community forest developers with a focus on the process of development, the conflict resolution strategies used, and the successes and failures throughout the process. The findings from this thesis indicate that community forest developers engage in a process that I call Developing a Community Forest. This process includes five categories of action: Building an Idea of Community Forestry, Being Aware of the Box, Coming Toward Conflict, Using Dispute Resolution Strategies, and Practicing Community Forestry. By articulating this process future community forest developers can access the methods of conflict resolution described in this thesis in their attempts to successfully develop community forestry in other local forest areas.
8

Growth and nutrient allocation of Douglas-fir seedlings : response to varying ammonium : nitrate ratios and to different methods of nursery fertilizer application

Everett, Kim 16 November 2009 (has links)
Regeneration of Douglas-fir following harvesting has proven difficult on many sites in British Columbia. As a result, alternative nursery practices are being explored to improve seedling growth. Using two experiments I aimed to identify an improved nutritional program for Douglas-fir seedlings. The objective of the first experiment was to identify the optimum nitrogen (N) source ratio for Douglas-fir between two inorganic sources of N, ammonium (NH4+) and nitrate (NO3-). Seedlings were grown in controlled environments in aeroponic culture with solutions containing 0:100, 20:80, 40:60, 60:40, 80:20 or 100:0 NH4+:NO3- ratios. Growth and nutrient allocation was observed for 45 days. Different NH4+ and NO3-ratios resulted in significant differences in growth and nutrient allocation. Seedlings grown in solutions containing abundant and relatively equal portions of NH4+ and NO3- were characterized by the greatest relative growth rates, greatest biomass and stable internal nitrogen concentrations. Seedlings grown in solutions containing high NH4+ (80:20 and 100:0 NHS+:NO3-) concentrations were characterized by lower relative growth rates, less biomass, lower internal nutrient concentrations and lower rates of photosynthesis and root respiration compared to seedlings with less NH4+ (20:80, 40:60 and 60:40 NH4+:NO3-). Seedlings appeared to take up a greater proportion of NH4+ than NO3- from solution. The objective of the second experiment was to examine the implications of two nursery fertilization regimes for growth and nutrient dynamics. Seedlings were grown in a nursery with nutrients added at a constant rate (conventional fertilization) or at an exponentially increasing rate of 2% day-1 (exponential nutrient loading). At the time of planting, half of the conventionally fertilized seedlings were planted with slow release fertilizer packets. Growth and nutrient allocation was observed for two years following planting. In the field experiment, although exponential nutrient loading applied 25% more N in the nursery compared to the conventional regime, no benefits in growth or nutrient allocation were found. Two years after planting, there were no significant differences in height, root collar diameter or total dry mass between seedlings grown under the different nursery fertilizer regimes. In contrast, seedlings planted with additional fertilizer consistently outperformed seedlings grown with exponential nutrient loading, with greater height, root collar diameter and dry mass. Two growing seasons after planting there were no significant differences among treatments in whole-plant N concentrations.
9

Fine-scale, multidimensional spatial patterns of forest canopy structure derived from remotely sensed and simulated datasets

Frazer, Gordon Wilson 07 April 2010 (has links)
Forests are not simply storehouses of timber or wood fibre for human consumption and economic development. They represent structurally and ecologically rich habitat for an estimated 40 percent of the earth's extant species, and form the functional interface between the biosphere and atmosphere for some 27 percent of the earth's terrestrial surface. Forests, therefore, play a vital role in the maintenance of biodiversity and the regulation of local to global scale ecosystem processes and functions. Present strategies for conserving biodiversity in managed forests are based on the notion that maintaining the full range of structural conditions historically present in natural forests is the best approach for assuring the long-term persistence of a broad range of native species. The overarching goal of this dissertation is to contribute to the development of novel forest measurements that are relevant to organisms and ecosystems, and much needed by forest scientists and managers to recognize and retain the key elements and patterns of forest structure that are crucial for the conservation of forest biodiversity. This study focuses explicitly on fine-spatial-scale, multidimensional patterns of forest canopy structure based on the assumption that the 'canopy' is the primary focal site of complex interactions between vegetation and the physical enviromnent. Two disparate remote sensing technologies-ground-based hemispherical (fisheye) canopy photography and airborne discrete-return LiDAR-are employed to characterize angular, vertical, and horizontal patterns of forest canopy structure. A quantitative technique is developed for precise measurements of gap fraction (P), element clumping (O), mean projection coefficient (G), and leaf area index (L) from sequences (sets) of black and white pixels extracted at specific view angles in digital fisheye photos. Results are compared with three other leading techniques and validated using well-documented simulated and real fisheye photosets. Variables P, O, G, and L control light capture and penetration in forest canopies, and are key input parameters for process-based models of stand productivity, stand dynamics, and material (CO2 and H20) and energy fluxes between the canopy and atmosphere. Findings show that this new technique consistently produced the best estimates of stand LAI in each of the three experimental forest sites. However, further validation work is required to determine the adequacy of these methods in other closed and discontinuous canopies. Finally, a methodological framework is devised for quantifying, classifying, and comparing fine-spatial-scale vertical and horizontal patterns of canopy structure derived from airborne LiDAR data. This methodology is tested with simulated forest canopies and ultimately demonstrated using an airborne LiDAR dataset collected over very young to old, coastal Douglas-fir/western hemlock forests on Vancouver Island, British Columbia. A pseudo 'space-for-time substitution' sampling approach is used to investigate age-related developmental changes in canopy structure at decadal and century time scales. Discrete classes of vertical and horizontal canopy structure are identified by k-means partitioning. The structural differences found among age-classes were consistent with the characteristics, patterns, and dynamics predicted by generalized models of stand development for similar coastal Douglas-fir/western hemlock forests of northwestern North America.
10

Understanding the forest structure: development of tools for identification and delineation of individual trees using LiDAR.

Loos, Rafael 16 November 2010 (has links)
LiDAR (Light Detection and Ranging) is currently being used to extract the biophysical characteristics of forests. LiDAR can provide extensive information about tree canopies; pulses reflected back to the sensor can represent understory vegetation as well as partial tree canopies below the dominant trees. Canopy structure can yield valuable clues about the biodiversity, and processes affecting the ecology of forest stands. In addition, structural information can provide insight into other processes such as fire behaviour and the distribution of fuels. This thesis focuses in developing tools to better understand the forest structure. The tools are computer-based algorithms that use LiDAR data as input and provide output with detailed information about the different layers of vegetation in a forested area. Three main modules are used in this study: (1) treetop identification, (2) delineation of canopies for the dominant layer of vegetation, and (3) delineation of partial canopies underneath this dominant layer. The study area was located in the Greater Victoria Water District, west of Victoria, British Columbia, Canada. Nine plots were chosen to represent the study area. A complete census was conducted in the summer of 2005 to provide information about tree, diameter at breast height (DBH), and tree dominance (based on the criteria: suppressed, intermediate, codominant and dominant). Results show that the algorithm is able to properly identify and delineate the majority of trees in the study areas. The third module, partial canopy delineation, also presents promising results with the dataset used. Newer LiDAR systems, with higher number of returns, will definitely provide better datasets with more information of the different layers within the forest, increasing the identification and delineation of these partial trees. Need of new field data is a must for future work and for further tests with the algorithm.

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