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Using multispectral landsat and sentinel-2 satellite data to invest.gate vegetation change at mount st. helens since the great volcanic eruption in 1980

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Journal of mountain Science 2018年第9期15卷 1851-1867页

作者： Katharina TELTSCHER Fabian Ewald FASSNACHT Inst.tute of Geography and Geoecology Karlsruhe Institute of Technology

Long-term analyses of vegetation succession after catast.ophic events are of high interest.for an improved underst.nding of succession dynamics. However, in many st.dies such analyses were rest.icted to plot-based measurements. Contrarily, spatially continuous observations of succession dynamics over extended areas and timeperiods are sparse. Here, we applied a change vector analysis(CVA) to invest.gate vegetation succession dynamics at mount st. helens after the great volcanic eruption in 1980 using Landsat. We additionally applied a supervised random forest.classification using Sentinel-2 data to map the currently prevailing vegetation types. Change vector analysis was performed with the normalized difference vegetation index(NDVI) and the urban index(UI) for three subsequent decades after the eruption as well as for the whole observation time between 1984 and 2016. The influence of topography on the current vegetation dist.ibution was examined by comparing altitude, slope angles and aspect values of vegetation classes derived by the random forest.classification. WilcoxRank-Sum test.was applied to test.for significant differences between topographic properties of the vegetation classes inside and outside of the areas affected by the eruption. For the full time period, a total area of 516 km2 was identified as re-vegetated, whereas the area and magnitude of re-growing vegetation decreased during the three decades and migrated closer to the volcanic crater. Vegetation losses were mainly observed in regions unaffected by the eruption and related most.y to timber harvest.ng. The vegetation type classification reached a high overall accuracy of approximately 90%. 36 years after the eruption, coniferous and deciduous trees have est.blished at formerly devast.ted areas dominating with a proportion of 66%, whereas shrubs are more abundant in riparian zones. Sparse vegetation dominates at regions very close to the crater. Elevation was found to have a great influence on th

关键词： mount st. helens Vegetation change Remote sensing Change vector analysis (CVA) Supervised classification Topography Density-plots

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Food Security: Impact of European Settlement and Infrast.ucture on Columbia River Salmon Migration

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Open Journal of Soil Science 2021年第7期11卷 367-388页

作者： Kenneth R. Olson Cory D. Suski College of Agricultural Consumer and Environmental Sciences University of Illinois Urbana Illinois USA Department of Natural Resources College of Agricultural Consumer and Environmental Sciences University of Illinois Urbana Illinois USA

The 2000 km Columbia River is the longest.river in the Pacific Northwest.region of North America. It st.rts in British Columbia, Canada and flows through the st.tes of Oregon and Washington before discharging into Pacific Ocean near Cape Disappointment. The mouth of the Columbia River is a deep water harbor and 180 km of the river can be accessed by navigation. Based on flow volume, the river is the 4th largest.river in the United st.tes. The headwaters and approximately 800 km of the Columbia River lie in Canada. Columbia Lake and the Columbia Wetlands are located in British Columbia and are the headwaters of the Columbia River. The lake has an elevation of 820 m above sea level and drains to the Pacific Ocean near Ast.ria, Oregon. The Ocean tides flow up river to Portland, Oregon. This paper highlights how the geological and landscape resources of the Columbia River and tributaries watershed contributed to the economic development of this hist.rically rich region of North America. The Columbia River is one of the most.biologically diverse freshwater syst.ms in the United st.tes. The Columbia River syst.m with trails and cruise ships was designed to increase use of the Columbia River, to promote recreational tourism, and to create a generation of people who are willing to protect and provide environmental st.wardship of the river basin resources.

关键词： Bonneville Slide Land of Flowing Milk and Honey Lewis and Clark Expedition Missoula Flood mount st. helens Oregon Trail Willamette Valley

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