Soil water excess,as well as deficit,leads to vegetation stress,i.e.,photosynthesis decline,stomata closure,growth reduction,decrease in respiration and biomass production.Therefore,vegetation response can be used as ...Soil water excess,as well as deficit,leads to vegetation stress,i.e.,photosynthesis decline,stomata closure,growth reduction,decrease in respiration and biomass production.Therefore,vegetation response can be used as indicator of changing in soil conditions,which corresponds to such phenomena as drought or soil waterlogging and associated natural disasters.During last 20 years,National Oceanic and Atmosphere Administration,National Environmental Satellite Data and Information Services(NOAA/NESDIS)satellite-based vegetation health indices(VHI)were successfully used for monitoring environmentally-based vegetation stress,including droughts,fire risk,soil saturation and other natural hazards around the world.In this study,the VHI were applied to verify the possibility their utilization for detection landslide risk areas in Madeira Island.Vegetation condition index(VCI)and registered precipitation were analyzed together with information on landslide occurrence in recent years.展开更多
Forest fires occur in Portugal every year during late spring, summer and fall. However, the beginning and end of the most severe season of forest fires are very variable, as is their intensity, the area and the number...Forest fires occur in Portugal every year during late spring, summer and fall. However, the beginning and end of the most severe season of forest fires are very variable, as is their intensity, the area and the number of occurrences. It is obvious, that vegetation stress and droughts are strongly linked to the occurrence of forest fires and burned area, showing a strong response to the drought. The vegetation health index (VHI), retrieved from the NOAA/NESDIS, shows good results in the detection of droughts, monitoring vegetation conditions in different countries. VHI is computed combining two terms: vegetation condition index (VCI), and temperature condition index (TCI) reflecting moisture and thermal vegetation conditions. The main objective of this study was to investigate the potential of VHI-method to monitor environmental conditions, favourable to forest fires in Portugal. Results of the study show that 88% of forest fires with burned area higher than 1,000 ha in a week, are well related with vegetation stress or drought conditions, detected with VHI-method. The results also show that the monitoring of the evolution of the VHI indexes is important for prevention burnt areas, especially in the spring, since it can indicate conditions for vegetation growth, which increases the fuel availability and the fire risk in the summer.展开更多
文摘Soil water excess,as well as deficit,leads to vegetation stress,i.e.,photosynthesis decline,stomata closure,growth reduction,decrease in respiration and biomass production.Therefore,vegetation response can be used as indicator of changing in soil conditions,which corresponds to such phenomena as drought or soil waterlogging and associated natural disasters.During last 20 years,National Oceanic and Atmosphere Administration,National Environmental Satellite Data and Information Services(NOAA/NESDIS)satellite-based vegetation health indices(VHI)were successfully used for monitoring environmentally-based vegetation stress,including droughts,fire risk,soil saturation and other natural hazards around the world.In this study,the VHI were applied to verify the possibility their utilization for detection landslide risk areas in Madeira Island.Vegetation condition index(VCI)and registered precipitation were analyzed together with information on landslide occurrence in recent years.
文摘Forest fires occur in Portugal every year during late spring, summer and fall. However, the beginning and end of the most severe season of forest fires are very variable, as is their intensity, the area and the number of occurrences. It is obvious, that vegetation stress and droughts are strongly linked to the occurrence of forest fires and burned area, showing a strong response to the drought. The vegetation health index (VHI), retrieved from the NOAA/NESDIS, shows good results in the detection of droughts, monitoring vegetation conditions in different countries. VHI is computed combining two terms: vegetation condition index (VCI), and temperature condition index (TCI) reflecting moisture and thermal vegetation conditions. The main objective of this study was to investigate the potential of VHI-method to monitor environmental conditions, favourable to forest fires in Portugal. Results of the study show that 88% of forest fires with burned area higher than 1,000 ha in a week, are well related with vegetation stress or drought conditions, detected with VHI-method. The results also show that the monitoring of the evolution of the VHI indexes is important for prevention burnt areas, especially in the spring, since it can indicate conditions for vegetation growth, which increases the fuel availability and the fire risk in the summer.
