Global ETD Search

1	Användning av markfuktighetskartor för ståndortsanpassad plantering / Use of Depth-to-Water maps for site adapted planting Jakobsson, Malin January 2015 (has links) Digital depth-to-water maps can be produced from a digital elevation model (DEM). Then GIS- based algorithms are used to calculate water flows and the depth-to-water index classes dry, fresh, moist and wet. The purpose of this study was to investigate the possibility to use depth- to-water maps for site adapted planting. The results showed that use of depth-to-water maps for site adapted planting, roughly halved the proportion of improperly planted surfaces from an average of 9 % to 4 %. The variation in the values of proper surface decreased and the result became more even.. In addition, more pine than spruce was incorrectly planted. Without soil moisture maps, the proportion of improper pine and spruce was 66 % and 34 % respectively, and with soil moisture maps, the proportion of improper pine and spruce was 55 % and 45 % respectively. This shows that for regenerations planted without the depth-to-water maps, mostly pine was incorrectly planted, but for the regenerations planted with the depth-to-water maps, the proportions were similar for spruce and pine. The conclusion from the results indicated that depth-to-water-maps can improve site adapted planting. By using the maps it is possible to get a good overview of the conditions and terrain variations of the planting sites. Digital depth-to-water maps Depth-to-Water Index GIS Planting Regeneration.
2	Kvantifiering av förändrad grundvattennivå vid simulerad dikesrensning / Quantifying change of water table when simulating ditch network maintenance Fastrup, Elsa January 2024 (has links) Dikesrensning är en etablerad åtgärd inom skogproduktion i Sverige för att bevara dikenas förmåga att leda vatten, och den sänkta grundvattennivån som ökat trädens tillväxt. I denna studie skapades och testades ett verktyg för att prognostisera förändringen av grundvattennivån vid simulerad dikesrensning för att förstå dikesrensningens påverkan på trädens tillväxt och negativa miljöeffekter. Verktyget applicerar Depth-to-Water (DTW) metoden för att skatta grundvattendjupet som lägsta summerade höjdskillnad till härlett ytvattensystem, med topografin från en digital markmodell. För att skatta grundvattennivån efter dikesrensning, så applicerades DTW på en markmodell med simulerad dikesrensning. Den simulerade dikesrensningen redigerade höjdvärdet längs dikesbotten i markmodellen till att representera dikesdjupet bättre men inte tillräckligt för att efterlikna en dikesrensning. DTW-metoden testades med olika hydrologiska bearbetningsmetoder av markmodellen för härledning av ytvattensystem och med höjdskillnaden beräknad från markmodellen respektive den hydrologiskt bearbetade markmodellen. Hydrologiska bearbetningsmetoden med samtliga funktioner, fylla och gräva kopplingar mellan sänkor, och utjämna markytan, härledde det mest realistiska ytvattensystemet och skattade grundvattennivån med generellt lägst medelavvikelsejämfört med fältmätningar och andra hydrologiska bearbetningsmetoder. När höjdskillnaden beräknades från den hydrologiskt bearbetade markmodellen skattades grundvattennivån markant bättre. Verktygets metod för skattade grundvattennivå med lägst medelavvikelse var på 0,28 m och bias på 0,10 m, vilket inte är tillräckligt för att använda verktyget för beslutsunderlag. Fortsatta studier skulle behövas för en bättre skattad grundvattennivå och med utvecklad metod för att kunna använda verktyget som beslutsunderlag vid dikesrensning. / Ditch network maintenance (DNM) is an established forestry practice in Sweden to keep ditches ability to convey water, which lower the water table to increase tree growth. In this study, a tool was created and tested to forecast the change in groundwater table during DNM to understand the impact from DNM on tree growth and negative environmental effects. The tool applied the Depth-to-Water (DTW) method to estimate groundwater table depth as the lowest summed elevation difference to surface flow channels, with respect to the topography in a digital terrain model (DTM). To estimate the groundwater table after DNM, DTW was applied to a DTM with simulated DNM. Compared to field measures the DTM with simulated DNM had an improved representation of ditch depth than the DTM without, but not sufficiently to mimic a DNM. The DTW method was tested with different hydrological processing on the DTM for derivation of surface flow channels and with the elevation difference calculated from the DTM versus hydrologically processed DTM. The hydrological preprocessing method with all functions, filling and breaching sinks, and smoothing the ground surface, derived the most realistic surface flow channels and estimated the groundwater table with generally the lowest root mean standard deviation (RMSE) compared to field measurements and other hydrological processing methods. When the elevation difference is calculated from the hydrologically processed DTM it improved the estimated groundwater table. The tool's estimated groundwater table had the lowest RMSE of 0.28 m and a bias of 0.10 m, which is not enough to use the tool for decision support. Further studies would be needed for better estimated groundwater table and developed methods to be able to use the tool as decision support for DNM. Depth-to-Water DTW dikesrensning grundvattennivå ytvattensystem hydrologisk bearbetning markmodell GIS DTM
3	Kan digitala hjälpmedel användas förmer ståndortsanpassade föryngringar? / Could digital tools be used for more site adapted regenerations? Danielsson, Joakim, Emilie, Björkman January 2019 (has links) The aim of this study was to investigate if SI from HPR-data from harvesters and soil moisture classes from digital depth to water maps could be used to support site adaption of regenerations within stands. The study was made on pine and spruce stands in central Sweden. The number of plants/ha, plant height, growth and damage were measured at plot level and for these plots also soil moisture classes and SI were derived from digital maps and HPR. The study shows a potential using SI from HPR and depth to water maps for site adaption of regenerations and to vary tree species within stands. Variations of SI and soil moisture are important within stands regarding different tree species establishment, growth and damage. But also, for sites with medium SI were the choice between pine and spruce is not obvious and in stands with a high spread in SI. Site index growth depth to water maps soil moisture HPR pine spruce birch regenerations site adaption Engineering and Technology Teknik och teknologier Forest Science Skogsvetenskap
4	Predictive modeling of migratory waterfowl Kreakie, Betty Jane 20 October 2011 (has links) Several factors have contributed to impeding the progress of migratory waterfowl spatial modeling, such as (1) waterfowl’s reliance on wetlands, (2) lack of understanding about shifts in distributions through time, and (3) large-scale seasonal migration. This doctoral dissertation provides an array of tools to address each of these concerns in order to better understand and conserve this group of species. The second chapter of this dissertation addresses issues of modeling species dependent on wetlands, a dynamic and often ephemeral habitat type. Correlation models of the relationships between climatic variables and species occurrence will not capture the full habitat constraints of waterfowl. This study introduces a novel data source that explicitly models the depth to water table, which is a simulated long-term measure of the point where climate and geological/topographic water fluxes balance. The inclusion of the depth to water table data contributes significantly to the ability to predict species probability of occurrence. Furthermore, this data source provides advantages over traditional proxies for wetland habitat, because it is not a static measure of wetland location, and is not biased by sampling method. Utilizing the long-term banding bird data again, the third chapter examines the behavior of waterfowl niche selection through time. By using the methods developed in chapter two, probability of occurrence models for the 1950s and the 1990s were developed. It was then possible to detect movements in geographic and environmental space, and how movements in these two spaces are related. This type of analysis provides insight into how different bird species might respond to environment changes and potentially improve climate change forecasts. The final chapter presents a new method for predicting the migratory movement of waterfowl. The method incorporates not only the environmental constraints of stopover habitat, but also includes likely distance and bearing traveled from a source point. This approach uses the USGS’ banding bird database; more specifically, it relies on banding locations, which have multiple recoveries within short time periods. Models made from these banding locations create a framework of migration movement, and allow for predictions to be made from locations where no banding/recovery data are available. / text American black duck Blue-winged teal Canada goose Depth to water tables Mallard Migration Migratory waterfowl Niche Northern pintail North America Species distribution modeling Wetland Wood duck
5	Multispectral imaging of Sphagnum canopies: measuring the spectral response of three indicator species to a fluctuating water table at Burns Bog Elves, Andrew 02 May 2022 (has links) Northern Canadian peatlands contain vast deposits of carbon. It is with growing urgency that we seek a better understanding of their assimilative capacity. Assimilative capacity and peat accumulation in raised bogs are linked to primary productivity of resident Sphagnum species. Understanding moisture-mediated photosynthesis of Sphagnum spp. is central to understanding peat production rates. The relationship between depth to water table fluctuation and spectral reflectance of Sphagnum moss was investigated using multispectral imaging at a recovering raised bog on the southwest coast of British Columbia, Canada. Burns Bog is a temperate oceanic ombrotrophic bog. Three ecohydrological indicator species of moss were chosen for monitoring: S. capillifolium, S. papillosum, and S. cuspidatum. Three spectral vegetation indices (SVIs) were used to characterize Sphagnum productivity: the normalized difference vegetation index 660, the chlorophyll index, and the photochemical reflectance index. In terms of spectral sensitivity and the appropriateness of SVIs to species and field setting, we found better performance for the normalized difference vegetation index 660 in the discrimination of moisture mediated species-specific reflectance signals. The role that spatiotemporal scale and spectral mixing can have on reflectance signal fidelity was tested. We were specifically interested in the relationship between changes in the local water table and Sphagnum reflectance response, and whether shifting between close spatial scales can affect the statistical strength of this relationship. We found a loss of statistical significance when shifting from the species-specific cm2 scale to the spectrally mixed dm2 scale. This spatiospectral uncoupling of the moisture mediated reflectance signal has implications for the accuracy and reliability of upscaling from plot based measurements. In terms of species-specific moisture mediated reflectance signals, we were able to effectively discriminate between the three indicator species of Sphagnum along the hummock-to-hollow gradient. We were also able to confirm Sphagnum productivity and growth outside of the vascular growing season, establishing clear patterns of reflectance correlated with changes in the local moisture regime. The strongest relationships for moisture mediated Sphagnum productivity were found in the hummock forming species S. capillifolium. Each indicator Sphagnum spp. of peat has distinct functional traits adapted to its preferred position along the ecohydrological gradient. We also discovered moisture mediated and species-specific reflectance phenologies. These phenospectral characteristics of Sphagnum can inform future monitoring work, including the creation of a regionally specific phenospectral library. It’s recommended that further close scale multispectral monitoring be carried out incorporating more species of moss, as well as invasive and upland species of concern. Pervasive vascular reflectance bias in remote sensing products has implications for the reliability of peatland modelling. Avoiding vascular bias, targeted spectral monitoring of Sphagnum indicator species provides a more reliable measure for the modelling of peatland productivity and carbon assimilation estimates. / Graduate peatland peatland restoration peatland monitoring peatland modelling peat peat moss multispectral multispectral imaging multicamera array multitemporal multiple linear regression linear mixed effects Sphagnum sphagna Sphagnum capillifolium Sphagnum papillosum Sphagnum cuspidatum spatiospectral uncoupling near-sensing remote sensing phenospectral phenology phenologies phenospectral bias phenospectral libraries carbon assimilation carbon dioxide carbon dynamics carbon emissions carbon geographies carbon mineralization carbon sequestration carbon source carbon sink carbon storage irrecoverable carbon climate forcing methane Ecological Restoration restoration ecology ecohydrology ecohydrological restoration hydrology ecohydrological gradients ecological integrity reflectance nature based solutions ombrotrophic moss raised peatland mires mires photochemical reflectance index normalized difference vegetation index chlorophyll index climate change climate forcing climate envelope climatope nonvascular vascular bias plant functional type plant functional types structure equation models spectral vegetation indices hummock hollow acrotelm catotelm diplotelmic biocrusts organic soil periodicity moisture deficit senescence rejuvenescence productivity photosynthesis light use efficiency photosynthetic function photosynthetically active radiation water table hydrology rewetting depth to water table landscape change landscape degradation peat subsidence Burns Bog

1

Page generated in 0.1521 seconds