Coordinating lead authors: Julia A. Jones and Xiaohua (Adam) Wei Lead authors: Meine van Noordwij... more Coordinating lead authors: Julia A. Jones and Xiaohua (Adam) Wei Lead authors: Meine van Noordwijk, Irena F. Creed, Mark Gush, David Ellison, Juan A. Blanco, Kevin Bishop, Steven G. McNulty and Emma Archer Contributing authors: Aida Bargués Tobella, Leendert A. (Sampurno) Bruijnzeel, Peter Duinker, David Foster, Aster Gebrekirstos, Krysta Giles-Hansen, Andrew Hacket-Pain, Richard J. Harper, Ulrik Ilstedt, Qiang Li, Yingchun Liao, Anders Malmer, Hosea Mwangi, Chloé Orland, James Steenberg, Yi Wang, Fiona Worthy, Jianchu Xu and Mingfang Zhang
ABSTRACT On the Boreal Plain, the boreal mixed-wood forest is characterized by complex drainage b... more ABSTRACT On the Boreal Plain, the boreal mixed-wood forest is characterized by complex drainage basins, with hydrologically organized to disorganized drainage networks. Within these drainage basins, surface saturated areas (SSAs) have been shown to be important in regulating nutrient loading to lakes. For example, nutrient loading may be low when SSAs are small and hydrologically disconnected from the drainage network, but nutrient loading may increase when SSAs expand and hydrologically connect to the lake. We sought to derive an INDEX of the hydrological connectedness of SSAs to lakes within Moose Lake, an experimental drainage basin on the Boreal Plain. A hydrologic analysis was conducted to capture hydrologic dynamics at inter-annual (LANDSAT TM, bands 2 and 5, 25 m spatial resolution) and intra-annual (RADARSAT S1, C-band, 5.3 GHz, HH-polarized, 12.5 m spatial resolution) scales. Based on this analysis, remotely sensed images were selected representing conditions ranging from very dry (Antecedent Moisture Index [AMI]=0-10 mm), dry (11-20 mm), moist (21-30 mm), wet (31-40 mm), to very wet (41-50 mm). For LANDSAT analyses, TM band (5) and hybrid bands (5/2, 2/5) were classified to derive maps of the INDEX and change detection techniques were applied to determine the variability in the INDEX under different AMI conditions. For RADARSAT analyses, images were grouped into different AMI categories. Once the radar backscatter was calibrated, a principal component analysis was performed on all images within each AMI category. The SSAs extracted from the principal components were used to generate the INDEX with respect to the size and organization of these areas. For both remote sensing platforms, the results were corroborated using reference data including ground-based observations. Image analyses indicated that during dry periods, SSAs were small and hydrologically disconnected from Moose Lake. As AMI increased, the SSAs expanded, creating a larger area of hydrologically connected SSAs to the lake. The increase in hydrologically connected SSAs corresponded to an increase in the water levels and nutrient status of the lake. Practical significance of this research lies in the creation of maps of the potential susceptibility of drainage basins to disturbances. Drainage basins with SSAs that are permanently or transiently (during wet conditions) connected via surface hydrologic pathways to the lake would be identified as particularly susceptible to disturbance. This emphasizes the need to preserve the forests near these SSAs in order to protect the lakes within these drainage basins.
In northern forests, large amounts of missing N that dominate N balances at scales ranging from s... more In northern forests, large amounts of missing N that dominate N balances at scales ranging from small watersheds to large regional drainage basins may be related to N-gas production by soil microbes. We measured denitrification rates in forest soils in northeastern North America along a N deposition gradient to determine whether N-gas fluxes were a significant fate for atmospheric N inputs and whether denitrification rates were correlated with N availability, soil O2 status, or forest type. We quantified N2 and N2O fluxes in the laboratory with an intact-core method and monitored soil O2, temperature and moisture in three forests differing in natural and anthropogenic N enrichment: Turkey Lakes Watershed, Ontario; Hubbard Brook Experimental Forest, New Hampshire; and Bear Brook Watershed, Maine (fertilized and reference plots in hardwood and softwood stands). Total N-gas flux estimates ranged from <1 in fertilized hardwood uplands at Bear Brook to >100 kg N ha(-1) year(-1) in ...
The application of remote sensing data to empirical models of inland surface water chlorophyll-a ... more The application of remote sensing data to empirical models of inland surface water chlorophyll-a concentrations (chl-a) has been in development since the launch of the Landsat 4 satellite series in 1982. However, establishing an empirical model using a chl-a retrieval algorithm is difficult due to the spatial heterogeneity of inland lake water properties. Classification of optical water types (OWTs; i.e., differentially observed water spectra due to differences in water properties) has grown in favour in recent years over traditional non-turbid vs. turbid classifications. This study examined whether top-of-atmosphere reflectance observations in visible to near-infrared bands from Landsat 4, 5, 7, and 8 sensors can be used to identify unique OWTs using a guided unsupervised classification approach in which OWTs are defined through both remotely sensed reflectance and surface water chemistry data taken from samples in North American and Swedish lakes. Linear regressions of algorithms ...
Coordinating lead authors: Julia A. Jones and Xiaohua (Adam) Wei Lead authors: Meine van Noordwij... more Coordinating lead authors: Julia A. Jones and Xiaohua (Adam) Wei Lead authors: Meine van Noordwijk, Irena F. Creed, Mark Gush, David Ellison, Juan A. Blanco, Kevin Bishop, Steven G. McNulty and Emma Archer Contributing authors: Aida Bargués Tobella, Leendert A. (Sampurno) Bruijnzeel, Peter Duinker, David Foster, Aster Gebrekirstos, Krysta Giles-Hansen, Andrew Hacket-Pain, Richard J. Harper, Ulrik Ilstedt, Qiang Li, Yingchun Liao, Anders Malmer, Hosea Mwangi, Chloé Orland, James Steenberg, Yi Wang, Fiona Worthy, Jianchu Xu and Mingfang Zhang
ABSTRACT On the Boreal Plain, the boreal mixed-wood forest is characterized by complex drainage b... more ABSTRACT On the Boreal Plain, the boreal mixed-wood forest is characterized by complex drainage basins, with hydrologically organized to disorganized drainage networks. Within these drainage basins, surface saturated areas (SSAs) have been shown to be important in regulating nutrient loading to lakes. For example, nutrient loading may be low when SSAs are small and hydrologically disconnected from the drainage network, but nutrient loading may increase when SSAs expand and hydrologically connect to the lake. We sought to derive an INDEX of the hydrological connectedness of SSAs to lakes within Moose Lake, an experimental drainage basin on the Boreal Plain. A hydrologic analysis was conducted to capture hydrologic dynamics at inter-annual (LANDSAT TM, bands 2 and 5, 25 m spatial resolution) and intra-annual (RADARSAT S1, C-band, 5.3 GHz, HH-polarized, 12.5 m spatial resolution) scales. Based on this analysis, remotely sensed images were selected representing conditions ranging from very dry (Antecedent Moisture Index [AMI]=0-10 mm), dry (11-20 mm), moist (21-30 mm), wet (31-40 mm), to very wet (41-50 mm). For LANDSAT analyses, TM band (5) and hybrid bands (5/2, 2/5) were classified to derive maps of the INDEX and change detection techniques were applied to determine the variability in the INDEX under different AMI conditions. For RADARSAT analyses, images were grouped into different AMI categories. Once the radar backscatter was calibrated, a principal component analysis was performed on all images within each AMI category. The SSAs extracted from the principal components were used to generate the INDEX with respect to the size and organization of these areas. For both remote sensing platforms, the results were corroborated using reference data including ground-based observations. Image analyses indicated that during dry periods, SSAs were small and hydrologically disconnected from Moose Lake. As AMI increased, the SSAs expanded, creating a larger area of hydrologically connected SSAs to the lake. The increase in hydrologically connected SSAs corresponded to an increase in the water levels and nutrient status of the lake. Practical significance of this research lies in the creation of maps of the potential susceptibility of drainage basins to disturbances. Drainage basins with SSAs that are permanently or transiently (during wet conditions) connected via surface hydrologic pathways to the lake would be identified as particularly susceptible to disturbance. This emphasizes the need to preserve the forests near these SSAs in order to protect the lakes within these drainage basins.
In northern forests, large amounts of missing N that dominate N balances at scales ranging from s... more In northern forests, large amounts of missing N that dominate N balances at scales ranging from small watersheds to large regional drainage basins may be related to N-gas production by soil microbes. We measured denitrification rates in forest soils in northeastern North America along a N deposition gradient to determine whether N-gas fluxes were a significant fate for atmospheric N inputs and whether denitrification rates were correlated with N availability, soil O2 status, or forest type. We quantified N2 and N2O fluxes in the laboratory with an intact-core method and monitored soil O2, temperature and moisture in three forests differing in natural and anthropogenic N enrichment: Turkey Lakes Watershed, Ontario; Hubbard Brook Experimental Forest, New Hampshire; and Bear Brook Watershed, Maine (fertilized and reference plots in hardwood and softwood stands). Total N-gas flux estimates ranged from <1 in fertilized hardwood uplands at Bear Brook to >100 kg N ha(-1) year(-1) in ...
The application of remote sensing data to empirical models of inland surface water chlorophyll-a ... more The application of remote sensing data to empirical models of inland surface water chlorophyll-a concentrations (chl-a) has been in development since the launch of the Landsat 4 satellite series in 1982. However, establishing an empirical model using a chl-a retrieval algorithm is difficult due to the spatial heterogeneity of inland lake water properties. Classification of optical water types (OWTs; i.e., differentially observed water spectra due to differences in water properties) has grown in favour in recent years over traditional non-turbid vs. turbid classifications. This study examined whether top-of-atmosphere reflectance observations in visible to near-infrared bands from Landsat 4, 5, 7, and 8 sensors can be used to identify unique OWTs using a guided unsupervised classification approach in which OWTs are defined through both remotely sensed reflectance and surface water chemistry data taken from samples in North American and Swedish lakes. Linear regressions of algorithms ...
Uploads
Papers