Spectral Reflections and Biological Integrity of the Land-Water Interface
Investigators (most current known information)
Proposal Abstract
The objectives of the project were to:
- quantify differences in seasonal wetland attributes along an arid to semi-humid environmental gradient,define relationships between ground and satellite measurements of seasonal wetland basins, and
- link spectral landscape signatures to changes in seasonal wetland conditions as projected under a global climate change scenario.
Fifteen seasonal wetland basins were sampled in South Dakota and Israel along existing precipitation gradients. Field measurements were performed within each basin to describe physical, chemical and biological attributes. In addition, satellite measurements of reflectance from each basin were estimated using LANDSAT Thematic Mapper imagery (Brightness, Greenness, NDVI, Wetness). Correlation and regression analyses were performed to define relationships between field measurements and remote indices of landscape condition.
Wetland basins extended across a precipitation gradient of 50 mm to 720 mm per year, ranging in size from 0.09 to 26.9 ha and 2.0 to 100 cm in depth. Substrate was composed mostly of clay size material in arid basins and sand in wetter basins of South Dakota. Benthic organic matter ranged fro 0.01% in arid basins of Israel to 21.3% in wetter basins of South Dakota. Ammonium was the dominant form of inorganic nitrogen in Israel (avg. 0.235 mg/L) and South Dakota (avg. 0.232 mg/L). Nitrate and nitrite nitrogen concentrations were undetectable or present in very low concentrations. A large pool of total phosphorus was evident in both regions. Total phosphorus concentrations in South Dakota averaged 0.73 mg/L while soluble reactive phosphorus in Israel averaged 16.84 mg/L. Specific conductance values averaged 170 uS/cm in Israel and 240 uS/cm in South Dakota increasing exponentially across combined precipitation gradients. Dissolved oxygen concentrations averaged 9.9 mg/L in Israel and 3.0 mg/L in South Dakota.
Vegetation samples included 17 species from Israel basins and 24 from South Dakota Basins. Stem densities ranged from 0 to 13, 930 per square meter and dry weight biomass ranged from 0 to 360 g DW per square meter. Greatest densities and biomass were observed from seasonal basins in South Dakota. Several species exhibited regional occurrence though emergent forms were prevalent in most basins. Greater abundance of low growing emergent vegetation occurred in drier basins of South Dakota with increasing prevalence of large growth forms along the precipitation gradient.
Forty-nine invertebrate taxa were observed from South Dakota basins, including representatives from 5 phyla, 7 classes, 11 orders, and 40 families. Annelida, Crustacea, and Insecta contributed most to total abundance with Diptera and Coleoptera (Insecta) contributing the greatest number of families. Total invertebrate densities ranged from 1,967 to 64,590 per square meter and biomass ranged from 0.1 to 204 g DW per square meter in South Dakota basins. Detritivorous collector gatherers and filters were numerically most abundant.
Normalized vegetation index (NDVI) values for wetland basins ranged from 0.053 to 0.560. Range and average values were higher from South Dakota than Israel basins. Significant correlations were observed between several field attributes and spectral signature of landscape condition. Brightness values were significantly correlated with ground measurements of mean annual precipitation, basin depth, substrate texture, conductance, nitrite-nitrogen, vegetation stem density and invertebrate density and biomass in South Dakota. NDVI values were found to be significantly correlated with vegetation biomass across precipitation gradients of both regions (Israel and South Dakota). Seventy five percent of the variability in NDVI values could be explained through multiple regression analysis using data for plant biomass, mean annual precipitation and basin depth.
Our results demonstrate difference in seasonal wetland systems along naturally occurring precipitation gradients. Wetland attributes along these two gradients are similar to those which may occur under a global climate change scenario. Climate is a major factor governing the distribution and characteristics of wetland basins. Mean global temperatures have increased 0.5 degrees C over the past 100 years and are expected to increase an additional 1-3 degrees C by the year 2100. Higher evapotranspiration, lower soil moisture, reduced snow cover, higher albedo, shorter growing season and reduced wetland hydroperiod are expected to accompany changes in mean global temperatures. Should these changes in climate occur, seasonal wetland systems may experience physical, chemical, and biological changes toward characteristics expected from a drier climate. Basin depths may decrease and hydroperiod shorten under drier conditions. Periods of dessication will likely increase, leading to shifts in vegetation community structure and greater prevalence of generalist, detritivore invertebrates. Many of these changes could be detected using remotely sensed signatures of landscape condition. Direct measurements of basin extent in combination with statistical relationships between basin attributes and reflectance signatures would facilitate long-term monitoring of wetland basins.
Three major contributions have been generated from this effort. First, seasonal wetland basins exhibit different physical, chemical and biological characteristics along natural precipitation gradients. Second, observed differences along these gradients are similar to those predicted under a global climate change scenario. Third, observed differences in wetland attributes can be detected using remotely sensed signatures of landscape condition. These conclusions and their supporting data may serve as a framework for future global change monitoring.
- quantify differences in seasonal wetland attributes along an arid to semi-humid environmental gradient,
- define relationships between ground and satellite measurements of seasonal wetland basins, and
- link spectral landscape signatures to changes in seasonal wetland conditions as projected under a global climate change scenario.
Fifteen seasonal wetland basins were sampled in South Dakota and Israel along existing precipitation gradients. Field measurements were performed within each basin to describe physical, chemical and biological attributes. In addition, satellite measurements of reflectance from each basin were estimated using LANDSAT Thematic Mapper imagery (Brightness, Greenness, NDVI, Wetness). Correlation and regression analyses were performed to define relationships between field measurements and remote indices of landscape condition.
Wetland basins extended across a precipitation gradient of 50 mm to 720 mm per year, ranging in size from 0.09 to 26.9 ha and 2.0 to 100 cm in depth. Substrate was composed mostly of clay size material in arid basins and sand in wetter basins of South Dakota. Benthic organic matter ranged fro 0.01% in arid basins of Israel to 21.3% in wetter basins of South Dakota. Ammonium was the dominant form of inorganic nitrogen in Israel (avg. 0.235 mg/L) and South Dakota (avg. 0.232 mg/L). Nitrate and nitrite nitrogen concentrations were undetectable or present in very low concentrations. A large pool of total phosphorus was evident in both regions. Total phosphorus concentrations in South Dakota averaged 0.73 mg/L while soluble reactive phosphorus in Israel averaged 16.84 mg/L. Specific conductance values averaged 170 uS/cm in Israel and 240 uS/cm in South Dakota increasing exponentially across combined precipitation gradients. Dissolved oxygen concentrations averaged 9.9 mg/L in Israel and 3.0 mg/L in South Dakota.
Vegetation samples included 17 species from Israel basins and 24 from South Dakota Basins. Stem densities ranged from 0 to 13, 930 per square meter and dry weight biomass ranged from 0 to 360 g DW per square meter. Greatest densities and biomass were observed from seasonal basins in South Dakota. Several species exhibited regional occurrence though emergent forms were prevalent in most basins. Greater abundance of low growing emergent vegetation occurred in drier basins of South Dakota with increasing prevalence of large growth forms along the precipitation gradient.
Forty-nine invertebrate taxa were observed from South Dakota basins, including representatives from 5 phyla, 7 classes, 11 orders, and 40 families. Annelida, Crustacea, and Insecta contributed most to total abundance with Diptera and Coleoptera (Insecta) contributing the greatest number of families. Total invertebrate densities ranged from 1,967 to 64,590 per square meter and biomass ranged from 0.1 to 204 g DW per square meter in South Dakota basins. Detritivorous collector gatherers and filters were numerically most abundant.
Normalized vegetation index (NDVI) values for wetland basins ranged from 0.053 to 0.560. Range and average values were higher from South Dakota than Israel basins. Significant correlations were observed between several field attributes and spectral signature of landscape condition. Brightness values were significantly correlated with ground measurements of mean annual precipitation, basin depth, substrate texture, conductance, nitrite-nitrogen, vegetation stem density and invertebrate density and biomass in South Dakota. NDVI values were found to be significantly correlated with vegetation biomass across precipitation gradients of both regions (Israel and South Dakota). Seventy five percent of the variability in NDVI values could be explained through multiple regression analysis using data for plant biomass, mean annual precipitation and basin depth.
Our results demonstrate difference in seasonal wetland systems along naturally occurring precipitation gradients. Wetland attributes along these two gradients are similar to those which may occur under a global climate change scenario. Climate is a major factor governing the distribution and characteristics of wetland basins. Mean global temperatures have increased 0.5 degrees C over the past 100 years and are expected to increase an additional 1-3 degrees C by the year 2100. Higher evapotranspiration, lower soil moisture, reduced snow cover, higher albedo, shorter growing season and reduced wetland hydroperiod are expected to accompany changes in mean global temperatures. Should these changes in climate occur, seasonal wetland systems may experience physical, chemical, and biological changes toward characteristics expected from a drier climate. Basin depths may decrease and hydroperiod shorten under drier conditions. Periods of dessication will likely increase, leading to shifts in vegetation community structure and greater prevalence of generalist, detritivore invertebrates. Many of these changes could be detected using remotely sensed signatures of landscape condition. Direct measurements of basin extent in combination with statistical relationships between basin attributes and reflectance signatures would facilitate long-term monitoring of wetland basins.
Three major contributions have been generated from this effort. First, seasonal wetland basins exhibit different physical, chemical and biological characteristics along natural precipitation gradients. Second, observed differences along these gradients are similar to those predicted under a global climate change scenario. Third, observed differences in wetland attributes can be detected using remotely sensed signatures of landscape condition. These conclusions and their supporting data may serve as a framework for future global change monitoring.
Outcome
No outcomes reported