Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of t...Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of this research was to study two northern California wild-land fires: Butte Humboldt Complex and Butte Lightning Complex of 2008 and assessment of vegetation recovery after the fires via ground based measurements and utilization of Landsat 5 imagery and analysis software to assess landscape change. Multi-temporal and burn severity dynamics and assessment through satellite imagery were used to visually ascertain levels of landscape change, under two temporal scales. Visual interpretation indicated noticeable levels of landscape change and relevant insight into the magnitude and impact of both wild-land fires. Normalized Burn Ratio (NBR) and delta NBR (DNBR) data allowed for quantitative analysis of burn severity levels. DNBR results indicate low severity and low re-growth for Butte Humboldt Complex “burned center” subplots. In contrast, DNBR values for Butte Lightning Complex “burned center” subplots indicated low-moderate burn severity levels.展开更多
Natural geological, chronic and acute release of volcanic gases can have a dramatic impact on vegetative ecosystems and potential impact on regional agriculture and human health. This research incorporates a series of...Natural geological, chronic and acute release of volcanic gases can have a dramatic impact on vegetative ecosystems and potential impact on regional agriculture and human health. This research incorporates a series of observations using leaf level gas exchange, chlorophyll fluorescence and remotely sensed reflectance measurements of vegetation experiencing chronic exposure to volcanic gas emissions;to develop techniques for monitoring the relative health of vegetation along the edge of an acute vegetative kill zone of a natural disaster and potential preeruption vegetation physiology. Experiments were conducted along an elevation gradient that corresponds to the SO2 gradient on vegetation along the south flank of Volcán Turrialba, Costa Rica. This study site is a natural environment with high volcanic degassing activity with significant SO2 emissions (n/d-0.281 ppm). Corresponding to an SO2 gradient, a substantial increase in CO2 concentration of (430-517 ppm) was identified. We further show the physiological interactions of SO2 and CO2 have on vegetation along the kill zone of this natural disaster can be assessed by examining the SO2/CO2 ratios. The physiological indices tested and relationships among measurements emphasized in this research will add to the assessment of the impact atmospheric volcanic gas emissions have on the physiology of surrounding vegetation as well as advance the capability of remotely sensed environmental stress in natural settings.展开更多
文摘Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of this research was to study two northern California wild-land fires: Butte Humboldt Complex and Butte Lightning Complex of 2008 and assessment of vegetation recovery after the fires via ground based measurements and utilization of Landsat 5 imagery and analysis software to assess landscape change. Multi-temporal and burn severity dynamics and assessment through satellite imagery were used to visually ascertain levels of landscape change, under two temporal scales. Visual interpretation indicated noticeable levels of landscape change and relevant insight into the magnitude and impact of both wild-land fires. Normalized Burn Ratio (NBR) and delta NBR (DNBR) data allowed for quantitative analysis of burn severity levels. DNBR results indicate low severity and low re-growth for Butte Humboldt Complex “burned center” subplots. In contrast, DNBR values for Butte Lightning Complex “burned center” subplots indicated low-moderate burn severity levels.
文摘Natural geological, chronic and acute release of volcanic gases can have a dramatic impact on vegetative ecosystems and potential impact on regional agriculture and human health. This research incorporates a series of observations using leaf level gas exchange, chlorophyll fluorescence and remotely sensed reflectance measurements of vegetation experiencing chronic exposure to volcanic gas emissions;to develop techniques for monitoring the relative health of vegetation along the edge of an acute vegetative kill zone of a natural disaster and potential preeruption vegetation physiology. Experiments were conducted along an elevation gradient that corresponds to the SO2 gradient on vegetation along the south flank of Volcán Turrialba, Costa Rica. This study site is a natural environment with high volcanic degassing activity with significant SO2 emissions (n/d-0.281 ppm). Corresponding to an SO2 gradient, a substantial increase in CO2 concentration of (430-517 ppm) was identified. We further show the physiological interactions of SO2 and CO2 have on vegetation along the kill zone of this natural disaster can be assessed by examining the SO2/CO2 ratios. The physiological indices tested and relationships among measurements emphasized in this research will add to the assessment of the impact atmospheric volcanic gas emissions have on the physiology of surrounding vegetation as well as advance the capability of remotely sensed environmental stress in natural settings.
