Scaling-up knowledge of growing-season net ecosystem exchange for long-term assessment of North Dakota grasslands under the Conservation Reserve Program
نویسنده
چکیده
Scaling-up knowledge of land-atmosphere net ecosystem exchange (NEE) from a single experimental site to numerous perennial grass fields in the Northern Great Plains (NGP) requires appropriate scaling protocols. We addressed this problem using synoptic data available from the Landsat sensor for 10 growing seasons (April 15 to September 30) over a North Dakota field-site, where we continuously measured CO2 exchange using a Bowen Ratio Energy Balance (BREB) system. NEE observed during the growing season at our fieldsite from 1997 to 2006 vacillated with drought and deluge, with net carbon (C) losses to the atmosphere in 2006. We used stepwise linear regression with 10 years of Landsat and NEE data to construct and validate a model for estimating grassland growing-season NEE from field to landscape scales. Eighty-nine percent of the variability in NEE was explained by year, live biomass, carbon : nitrogen ratio, day of image acquisition, and annual precipitation. We then applied this model on 20 620 ha of North Dakota perennial grass fields enrolled in the Conservation Reserve Program (CRP), including 1272 fields east of the Missouri River and 165 fields west-river. Growing-season NEE for individual CRP fields was highly variable from 1997 to 2006, ranging from 366 to 692 g C m 2 growing season . Mean annual growing-season fluxes over 10 years for CRP fields located east-river and west-river were 317 g C m 2 growing season 1 and 239 g C m 2 growing season , respectively. Average cumulative growing-season NEE modeled for fields eastand west-river diverged from one another in 2002–2006, when west-river fields received o70% of the long-term annual average precipitation during these years. Results indicate assessment of conservation practices on grassland CO2 exchange during the growing season can be remotely estimated at field and landscape scales under variable environmental conditions and should be followed up with similar, spatially explicit investigations of NEE during the dormant season.
منابع مشابه
Nebraska Sand Hills: The Last Prairie
Although North American grasslands are diverse and biotically rich, their conservation has never received high priority. As a result, the prairie landscape has all but disappeared. However, one prairie region has retained its essential pre-Columbian features. This is the Nebraska Sand Hills Prairie, a 4.8 million ha stabilized dune region of Holocene origin. Because the Sand Hills lie at the he...
متن کاملGrazing and Haying Effects on Runoff and Erosion From a Former Conservation Reserve Program Site
Grazing and haying effects on runoff and erosion from a former Conservation Reserve Program (CRP) site near Streeter, North Dakota, were determined. Treatments included undisturbed CRP, twice-over rotational grazing, season-long grazing, haying, and burning. Runoff and erosion were measured from simulated rainfall which was applied to 3.7 x 10.7 m (12.0 X 35.1 ft) plots. Following an initial st...
متن کاملA new 2D block ordering system for wavelet-based multi-resolution up-scaling
A complete and accurate analysis of the complex spatial structure of heterogeneous hydrocarbon reservoirs requires detailed geological models, i.e. fine resolution models. Due to the high computational cost of simulating such models, single resolution up-scaling techniques are commonly used to reduce the volume of the simulated models at the expense of losing the precision. Several multi-scale ...
متن کاملSeasonal and Inter-Annual Variations in Carbon Dioxide Exchange over an Alpine Grassland in the Eastern Qinghai-Tibetan Plateau
This work analyzed carbon dioxide exchange and its controlling factors over an alpine grassland on the eastern Qinghai-Tibetan Plateau. The main results show that air temperature and photosynthetically active radiation are two dominant factors controlling daily gross primary production. Soil temperature and soil water content are the main factors controlling ecosystem respiration. Canopy photos...
متن کاملSoil Carbon Dioxide Emission as Influenced by Irrigation, Tillage, Cropping System, and Nitrogen Fertilization
Soil and crop management practices can influence CO2 emission from crop and grasslands and therefore on global warming. We examined the effects of two irrigation systems (irrigated vs. non-irrigated) and six management practices [no-till malt barley (Hordeum vulgaris L.) with 67 or 134 kg N ha (NTBFN), notill malt-barley with 0 kg N ha (NTBON), conventional-till malt barley with 67 or 134 kg N ...
متن کامل