NDVI, C₃AND C₄PRODUCTION, AND DISTRIBUTIONS IN GREAT PLAINS GRASSLAND LAND COVER CLASSES

Abstract

The distributions of C3 and C4 grasses were used to interpret the distribution, seasonal performance, and potential production of grasslands in the Great Plains of North America. Thirteen major grassland seasonal land cover classes were studied with data from three distinct sources. Normalized Difference Vegetation Index (NDVI) data derived from the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) sensor were collected for each pixel over a 5‐yr period (1989–1993), analyzed for quantitative attributes and seasonal relationships, and then aggregated by land cover class. Data from the State Soil Geographic (STATSGO) database were used to identify dominant plant species contributing to the potential production in each map unit. These species were identified as C3 or C4, and contributions to production were aggregated to provide estimates of the percentage of C3 and C4 production for each intersection of the STATSGO map units and the seasonal land cover classes. Carbon isotope values were obtained at specific sites from the soil organic matter of the upper horizon of soil cores and were related to STATSGO estimates of potential production. The grassland classes were distributed with broad northwest‐to‐southeast orientations. Some classes had large variations in C3 and C4 composition with high proportions of C4 species in the south and low proportions in the north. This diversity of photosynthetic types within land cover classes that cross regions of different temperature and precipitation results in similar seasonal patterns and magnitudes of NDVI. The easternmost class, 65, containing tallgrass prairie components, bluestem, Indiangrass, and switchgrass, possessed the highest maximum NDVI and time‐integrated NDVI values each year. Grassland classes varied over 5 yr from a high integrated NDVI mean of 4.9 in class 65 in the east to a low of 1.2 in class 76 (sand sage, blue grama, wheatgrass, and buffalograss) in the southwest. Although environmental conditions varied widely during the 5 yr, the rankings of class performance were consistent across years for these NDVI metrics. Land cover classes were less consistent in time of onset, which was often earlier in areas in the north dominated by C3 grasses than in areas to the south dominated by C4 grasses. At the level of seasonal land cover classes, no significant relationship was found between the proportions of C3 and C4 species and estimates of potential production derived from the STATSGO database or inferred from the seasonal patterns of NDVI. The isotopic data from specific sites and the potential production data from STATSGO suggest similar patterns of high proportional production by C4 species throughout the south and a decline in proportional production north of the central Great Plains. The land cover classes integrate ecosystem units that encompass a wide diversity of species and C3 and C4 proportions and provide a classification that consistently captures significant ecosystem parameters for the Great Plains.

Global and Regional Ecosystem Modeling: Databases of Model Drivers and Validation Measurements

“…The State Soil Geographic (STATSGO) database was used to estimate mean potential ANPP for map units related to soil surveys at each site (Tieszen et al 1997). These, or the more detailed county soil and range survey data, were mapped for each cell and used to display ANPP across the cell.…”

“…The NPP values (1921, 1922 were derived from land cover stratification and NPP values for all the other 920 cells of Tieszen were based on the STATSGO database to estimate mean potential aboveground production (ANPP) for map units related to soil surveys at each site (Tieszen et al 1997). 4) For Prince data, the total NPP values for cells with ID# 9001-9155 were for Midwest states in 1992, while the total NPP values for cells with ID# 9156-9220 were the mean from 1982 through 1996 for the state of Iowa.…”

Large regional-scale variation in C3/C4 distribution pattern of Inner Mongolia steppe is revealed by grazer wool carbon isotope composition

“…In grassland, the 13 C signal can vary considerably, which is primarily related to the presence of variable proportions of C3 and C4 photosynthetic types (Tieszen et al, 1997;Bird and Pousai, 1997;Collatz et al, 1998) and the large difference in carbon isotope discrimination ( 13 ) between them (Farquhar et al, 1989). Variation in the C3/C4 ratio has wide biogeochemical and land use implications: it affects the magnitude and seasonal distribution of biomass production, soil carbon storage, water use and nutrient cycling (Tieszen et al, 1997;Bird and Pousai, 1997;Epstein et al, 1998;Sage and Kubien, 2003;Semmartin et al, 2004). Hence, as it indicates the C3/C4 ratio, δ 13 C is a useful proxy of vital functions of grassland.…”

Grassland and Cropland Net Ecosystem Production of the U.S. Great Plains: Regression Tree Model Development and Comparative Analysis

“…Rangeland (grass) biomass strata or "classes" were derived from STATSGO estimates for a "normal year" from STATSGO estimates of rangeland production on a "normal" year [62] using an unsupervised clustering approach. Eight rangeland biomass strata were produced that captured the productivity and precipitation gradients of the central and western portions of the Great Plains ( Figure 2).…”