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- United States National Aeronautics and Space Administration: Publications (5)
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Articles 1 - 18 of 18
Full-Text Articles in Physical Sciences and Mathematics
Aboveground Carbon Responses To Experimental And Natural Hurricane Impacts In A Subtropical Wet Forest In Puerto Rico, Hervé Chevalier, Nicholas V.L. Brokaw, Sheila E. Ward, Jess K. Zimmerman, Aaron B. Shiels, John Bithorn, Samuel Matta Carmona
Aboveground Carbon Responses To Experimental And Natural Hurricane Impacts In A Subtropical Wet Forest In Puerto Rico, Hervé Chevalier, Nicholas V.L. Brokaw, Sheila E. Ward, Jess K. Zimmerman, Aaron B. Shiels, John Bithorn, Samuel Matta Carmona
USDA Wildlife Services: Staff Publications
Climate change and disturbance make it difficult to project long-term patterns of carbon sequestration in tropical forests, but large ecosystem experiments in these forests can inform predictions. The Canopy Trimming Experiment (CTE) manipulates two key components of hurricane disturbance, canopy openness and detritus deposition, in a tropical forest in Puerto Rico. We documented how the CTE and a real hurricane affected tree recruitment, biomass, and aboveground carbon storage over 15 years. In the CTE treatments, we trimmed branches, but we did not fell trees. We expected that during the 14-year period after initial canopy trimming, regrowth of branches and stems …
Ecophysio-Optical Traits Of Semiarid Nebraska Grasslands Under Different Juniperus Virginiana And Pinus Ponderosa Canopy Covers, Anastasios Mazis, Julie A. Fowler, Jeremy Hiller, Yuzhen Zhou, Brian Wardlow, David A. Wedin, Tala Awada
Ecophysio-Optical Traits Of Semiarid Nebraska Grasslands Under Different Juniperus Virginiana And Pinus Ponderosa Canopy Covers, Anastasios Mazis, Julie A. Fowler, Jeremy Hiller, Yuzhen Zhou, Brian Wardlow, David A. Wedin, Tala Awada
School of Natural Resources: Faculty Publications
Despite conservation efforts in the U.S. Great Plains, woody species have continued to expand at an unprecedented rate, threatening key ecosystem services and resilience. Cross-scale monitoring of these grasslands is key to successful integrative management strategies. In this study we measured plant optical traits derived from hyperspectral proximal sensing techniques with a field spectrometer, coupled with field-based measurements, including fluorescence and chlorophyll content, to determine the impacts of Juniperus virginiana and Pinus ponderosa expansion on grasslands health in Nebraska Sandhills, and investigated the use of optical-based approaches as indicators of successful monitoring of grasslands. Our results showed that higher woody …
Integrated Analysis Of Productivity And Biodiversity In A Southern Alberta Prairie, Ran Wang, John A. Gamon, Craig A. Emmerton, Haitao Li, Enrica Nestola, Gilberto Z. Pastorello, Olaf Menzer
Integrated Analysis Of Productivity And Biodiversity In A Southern Alberta Prairie, Ran Wang, John A. Gamon, Craig A. Emmerton, Haitao Li, Enrica Nestola, Gilberto Z. Pastorello, Olaf Menzer
School of Natural Resources: Faculty Publications
Grasslands play important roles in ecosystem production and support a large farming and grazing industry. An accurate and efficient way is needed to estimate grassland health and production for monitoring and adjusting management to get sustainable products and other ecosystem services. Previous studies of grasslands have shown varying relationships between productivity and biodiversity, with most showing either a positive or a hump-shaped relationship where productivity peaks at intermediate diversity. In this study, we used airborne imaging spectrometry combined with ground sampling and eddy covariance measurements to estimate the spatial pattern of production and biodiversity for two sites of contrasting productivity …
Interannual Variability In Dry Mixed-Grass Prairie Yield: A Comparison Of Modis, Spot, And Field Measurements, Donald C. Wehlage, John A. Gamon, Donnette Thayer, David V. Hildebrand
Interannual Variability In Dry Mixed-Grass Prairie Yield: A Comparison Of Modis, Spot, And Field Measurements, Donald C. Wehlage, John A. Gamon, Donnette Thayer, David V. Hildebrand
School of Natural Resources: Faculty Publications
Remote sensing is often used to assess rangeland condition and biophysical parameters across large areas. In particular, the relationship between the Normalized Difference Vegetation Index (NDVI) and above-ground biomass can be used to assess rangeland primary productivity (seasonal carbon gain or above-ground biomass “yield”). We evaluated the NDVI–yield relationship for a southern Alberta prairie rangeland, using seasonal trends in NDVI and biomass during the 2009 and 2010 growing seasons, two years with contrasting rainfall regimes. The study compared harvested biomass and NDVI from field spectrometry to NDVI from three satellite platforms: the Aqua and Terra Moderate Resolution Imaging Spectroradiometer (MODIS) …
Estimating Herbaceous Biomass Of Grassland Vegetation Using The Reference Unit Method, Eric D. Boyda, Jack L. Bulter, Lan Xu
Estimating Herbaceous Biomass Of Grassland Vegetation Using The Reference Unit Method, Eric D. Boyda, Jack L. Bulter, Lan Xu
The Prairie Naturalist
Aboveground net primary production provides valuable information on wildlife habitat, fire fuel loads, and forage availability. Aboveground net primary production in herbaceous plant communities is typically measured by clipping aboveground biomass. However, the high costs associated with physically harvesting plant biomass may prevent collecting sufficient data to account for natural spatial and temporal variability of vegetation at a landscape scale. Various double-sampling techniques have been developed to increase sample size while reducing cost. We applied a biomass estimation technique previously developed for estimating shrub biomass using representative samples or “reference units” to estimate herbaceous grassland biomass. Our reference units consisted …
Assessment Of A Rotenone Application Event At Mormon Island West Lake In Central Nebraska, Keith D. Koupal, Brian C. Peterson, Casey W. Schoenebeck
Assessment Of A Rotenone Application Event At Mormon Island West Lake In Central Nebraska, Keith D. Koupal, Brian C. Peterson, Casey W. Schoenebeck
Transactions of the Nebraska Academy of Sciences and Affiliated Societies
Fisheries managers applied rotenone to Mormon Island West in August of 2010 to renovate a fish community that was hypothesized to be unbalanced (i.e., dominated with gizzard shad and common carp) based on standardized survey results. We estimated species-specific biomass following the lake renovation to provide a baseline biomass estimate for a sand pit lake and to evaluate the effectiveness of standardized sampling gears. Gizzard shad (Dorosoma cepedianum) were abundant in all sampling gears, but mostly stock-size (>175 mm total length) and larger individuals were caught in gill and trap nets and sub-stock (≤175 mm total length) …
The Feasibility Of Producing Adequate Feedstock For Year-Round Cellulosic Ethanol Production In An Intensive Agricultural Fuelshed, Daniel R. Uden, Robert B. Mitchell, Craig R. Allen, Qingfeng Guan, Tim D. Mccoy
The Feasibility Of Producing Adequate Feedstock For Year-Round Cellulosic Ethanol Production In An Intensive Agricultural Fuelshed, Daniel R. Uden, Robert B. Mitchell, Craig R. Allen, Qingfeng Guan, Tim D. Mccoy
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
To date, cellulosic ethanol production has not been commercialized in the United States. However, government mandates aimed at increasing second-generation biofuel production could spur exploratory development in the cellulosic ethanol industry. We conducted an in-depth analysis of the fuelshed surrounding a starch-based ethanol plant near York, Nebraska that has the potential for cellulosic ethanol production. To assess the feasibility of supplying adequate biomass for year-round cellulosic ethanol production from residual maize (Zea mays) stover and bioenergy switchgrass (Panicum virgatum) within a 40-km road network service area of the existing ethanol plant, we identified ∼14,000 ha of marginally productive cropland within …
Grass And Canada Goldenrod (Solidago Canadensis) Competition And Implications For Management In The Northern Tallgrass Prairie, Alexander J. Smart, Gary E. Larson, Peter J. Bauman
Grass And Canada Goldenrod (Solidago Canadensis) Competition And Implications For Management In The Northern Tallgrass Prairie, Alexander J. Smart, Gary E. Larson, Peter J. Bauman
The Prairie Naturalist
Canada goldenrod (Solidago canadensis L.) is a native perennial forb that can form dense clonal patches and become weedy in pastures of the Northern Tallgrass Prairie Ecoregion. Our objectives were to determine 1) the competitive effects between Canada goldenrod and grass, 2) the relationship between Canada goldenrod stem density and grass biomass, and 3) the distribution of Canada goldenrod stem density at the pasture scale. We used regression analysis to develop a relationship between Canada goldenrod stem density and grass biomass. Additionally, we estimated the frequency distribution of Canada goldenrod stem density categories using three evenly distributed 100 × 100-m …
Effects Of Species, Water, And Nitrogen On Competition Among Three Prairie Grasses, Jerry L. Weatherford, Randall W. Myster
Effects Of Species, Water, And Nitrogen On Competition Among Three Prairie Grasses, Jerry L. Weatherford, Randall W. Myster
The Prairie Naturalist
We conducted an experiment to investigate effects of species, water (W), and nitrogen (N) on competition among little bluestem (Schizachyrium scoparium), sideoats grama (Bouteloua curtipendula), and indiangrass (Sorghastrum nutans). All biomass parameters and the root:shoot ratio of little bluestem were reduced by the presence off 1 of 2 other species, and its shoot biomass and total biomass were both increased by addition of N. Root and shoot biomass of sideoats grama were reduced by the presence of indiangrass and its total biomass was reduced by the presence of itself, whereas its shoot biomass was increased by addition of W at …
Forest Structure And Aboveground Biomass In The Southwestern United States From Modis And Misr, Mark Chopping, Crystal B. Schaaf, Feng Zhao, Anne W. Nolin, Gretchen G. Moisen, John V. Martonchik, Michael Bull
Forest Structure And Aboveground Biomass In The Southwestern United States From Modis And Misr, Mark Chopping, Crystal B. Schaaf, Feng Zhao, Anne W. Nolin, Gretchen G. Moisen, John V. Martonchik, Michael Bull
United States National Aeronautics and Space Administration: Publications
Red band bidirectional reflectance factor data from the NASA MODerate resolution Imaging Spectroradiometer (MODIS) acquired over the southwestern United States were interpreted through a simple geometric–optical (GO) canopy reflectance model to provide maps of fractional crown cover (dimensionless), mean canopy height (m), and aboveground woody biomass (Mg ha−1) on a 250 m grid. Model adjustment was performed after dynamic injection of a background contribution predicted via the kernel weights of a bidirectional reflectance distribution function (BRDF) model. Accuracy was assessed with respect to similar maps obtained with data from the NASA Multiangle Imaging Spectroradiometer (MISR) and to contemporaneous …
Characterizing 3d Vegetation Structure From Space: Mission Requirements, Forrest G. Hall, Kathleen Bergen, James B. Blair, Ralph Dubayah, Richard Houghton, George Hurtt, Josef Kellndorfer, Michael Lefsky, Jon Ranson, Sassan Saatchi, H.H. Shugart, Diane Wickland
Characterizing 3d Vegetation Structure From Space: Mission Requirements, Forrest G. Hall, Kathleen Bergen, James B. Blair, Ralph Dubayah, Richard Houghton, George Hurtt, Josef Kellndorfer, Michael Lefsky, Jon Ranson, Sassan Saatchi, H.H. Shugart, Diane Wickland
United States National Aeronautics and Space Administration: Publications
Human and natural forces are rapidly modifying the global distribution and structure of terrestrial ecosystems on which all of life depends, altering the global carbon cycle, affecting our climate now and for the foreseeable future, causing steep reductions in species diversity, and endangering Earth's sustainability. To understand changes and trends in terrestrial ecosystems and their functioning as carbon sources and sinks, and to characterize the impact of their changes on climate, habitat and biodiversity, new space assets are urgently needed to produce high spatial resolution global maps of the three-dimensional (3D) structure of vegetation, its biomass above ground, the carbon …
Mapping Biomass And Stress In The Sierra Nevada Using Lidar And Hyperspectral Data Fusion, Anu Swatantran, Ralph Dubayah, Dar A. Roberts, Michelle Hofton, J. Bryan Blair
Mapping Biomass And Stress In The Sierra Nevada Using Lidar And Hyperspectral Data Fusion, Anu Swatantran, Ralph Dubayah, Dar A. Roberts, Michelle Hofton, J. Bryan Blair
United States National Aeronautics and Space Administration: Publications
In this paper, we explored fusion of structural metrics from the Laser Vegetation Imaging Sensor (LVIS) and spectral characteristics from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) for biomass estimation in the Sierra Nevada. In addition, we combined the two sensors to map species-specific biomass and stress at landscape scale. Multiple endmember spectral mixture analysis (MESMA) was used to classify vegetation from AVIRIS images and obtain sub-pixel fractions of green vegetation, non-photosynthetic vegetation, soil, and shade. LVIS metrics, AVIRIS spectral indices, and MESMA fractions were compared with field measures of biomass using linear and stepwise regressions at stand (1 ha) …
Retrieval Of Canopy Height Using Moderate-Resolution Imaging Spectroradiometer (Modis) Data, Zhuosen Wang, Crystal B. Schaaf, Philip Lewis, Yuri Knyazikhin, Mitchell A. Schull, Alan H. Strahler, Tian Yao, Ranga B. Myneni, Mark J. Chopping, Bryan J. Blair
Retrieval Of Canopy Height Using Moderate-Resolution Imaging Spectroradiometer (Modis) Data, Zhuosen Wang, Crystal B. Schaaf, Philip Lewis, Yuri Knyazikhin, Mitchell A. Schull, Alan H. Strahler, Tian Yao, Ranga B. Myneni, Mark J. Chopping, Bryan J. Blair
United States National Aeronautics and Space Administration: Publications
In this study we use the 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF) product to develop multivariate linear regression models that estimate canopy heights over study sites at Howland Forest, Maine, Harvard Forest, Massachusetts and La Selva Forest, Costa Rica using (1) directional escape probabilities that are spectrally independent and (2) the directional spectral reflectances used to derive the directional escape probabilities. These measures of canopy architecture are compared with canopy height information retrieved from the airborne Laser Vegetation Imaging Sensor (LVIS). Both the escape probability and the directional reflectance approaches achieve good results, with …
Forest Canopy Height From The Multiangle Imaging Spectroradiometer (Misr) Assessed With High Resolution Discrete Return Lidar, Mark Chopping, Anne Nolin, Gretchen G. Moisen, John V. Martonchik, Michael Bull
Forest Canopy Height From The Multiangle Imaging Spectroradiometer (Misr) Assessed With High Resolution Discrete Return Lidar, Mark Chopping, Anne Nolin, Gretchen G. Moisen, John V. Martonchik, Michael Bull
United States National Aeronautics and Space Administration: Publications
In this study retrievals of forest canopy height were obtained through adjustment of a simple geometricoptical (GO) model against red band surface bidirectional reflectance estimates from NASA's Multiangle Imaging SpectroRadiometer (MISR), mapped to a 250 m grid. The soil-understory background contribution was partly isolated prior to inversion using regression relationships with the isotropic, geometric, and volume scattering kernel weights of a Li-Ross kernel-driven bidirectional reflectance distribution function (BRDF) model. The height retrievals were assessed using discrete return lidar data acquired over sites in Colorado as part of the Cold Land Processes Experiment (CLPX) and used with fractional crown cover retrievals …
Winterkill And Biomass Of The Painted Turtle In A South Dakota Wetland, Steven G. Platt, Zannita Fast Horse, Warren Cross, Sylvio Mannel, Thomas R. Rainwater
Winterkill And Biomass Of The Painted Turtle In A South Dakota Wetland, Steven G. Platt, Zannita Fast Horse, Warren Cross, Sylvio Mannel, Thomas R. Rainwater
The Prairie Naturalist
Winterkill occurs when drought conditions expose hibernating turtles to desiccation and lethaly cold temperatures. Winterkill is thought to represent a major source of mortality in northern populations of the painted turtle (Chrysemys picta), but few field observations are available. We herein reported on catastrophic winterkill among western painted turtle (C. pieta bellii) at Limestone Butte Lake (LBL) in western South Dakota during the winter of 2003-2004. Additionally, we used the carcasses of winterkilled turtles (n = 86) to estimate the standing crop biomass of the painted turtle at LBL (0.6 kg/ha). This was the only estimate …
Cross-Scale Morphology, Craig R. Allen, C.S. Holling
Cross-Scale Morphology, Craig R. Allen, C.S. Holling
Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications
The scaling of physical, biological, ecological and social phenomena has become a major focus of efforts to develop simple representations of complex systems. Much of the attention has been on discovering universal scaling laws that emerge from simple physical and geometric processes. But there are regular patterns of departures both from those scaling laws and from continuous distributions of attributes of systems; these departures often demonstrate the development of self-organized interactions between living systems and physical processes over narrower ranges of scale. Cross-scale morphology refers to morphological attributes of animals that are influenced by interaction with ecological structures and patterns …
Do Species And Functional Groups Differ In Acquisition And Use Of C, N And Water Under Varying Atmospheric Co2 And N Availability Regimes? A Field Test With 16 Grassland Species, Peter B. Reich, David Tilman, Joseph Craine, David Ellsworth, Mark G. Tjoelker, Johannes M. H. Knops, David A. Wedin, Shahid Naeem, Dan Bahauddin, Jenny Goth, Wendy Bengtson, Tali D. Lee
Do Species And Functional Groups Differ In Acquisition And Use Of C, N And Water Under Varying Atmospheric Co2 And N Availability Regimes? A Field Test With 16 Grassland Species, Peter B. Reich, David Tilman, Joseph Craine, David Ellsworth, Mark G. Tjoelker, Johannes M. H. Knops, David A. Wedin, Shahid Naeem, Dan Bahauddin, Jenny Goth, Wendy Bengtson, Tali D. Lee
School of Natural Resources: Faculty Publications
Summary:
• To evaluate whether functional groups have a similar response to global change, the responses to CO2 concentration and N availability of grassland species from several functional groups are reported here.
• Sixteen perennial grassland species from four trait-based functional groups (C3 grasses, C4 grasses, non-leguminous forbs, legumes) were grown in field mono-cultures under ambient or elevated (560 μmol mol-1) CO2using free-air CO2enrichment (FACE), in low N (unamended field soil) or high N (field soil + 4 g N m-2 years-1) treatments.
• There were no CO …
Changes In The Freshwater Mussel Community Of Lake St. Clair: From Unionidae To Dreissena Polymorpha In Eight Years, Thomas F. Nalepa, David J. Hartson, Gerald W. Gostenik, David L. Fanslow, Gregory A. Lang
Changes In The Freshwater Mussel Community Of Lake St. Clair: From Unionidae To Dreissena Polymorpha In Eight Years, Thomas F. Nalepa, David J. Hartson, Gerald W. Gostenik, David L. Fanslow, Gregory A. Lang
United States Department of Commerce: Staff Publications
To determine density changes in both the zebra mussel, Dreissena polymorpha, and native mussels, Unionidae, in Lake St. Clair, surveys were conducted in 1990, 1992, and 1994 and compared to a similar survey in 1986 when no D. polymorpha was found. Collection methods were the same each year; divers used the quadrat method to collect 10 replicate samples at 29 sites located throughout the lake. The total number of unionids collected declined from 281 in 1986, to 248 in 1990, 99 in 1992, and 6 in 1994, while the number of species collected in each of the four respective …