The principles of remotely estimating grassland cover density in an alpine meadow soil from space lie in the synchronous collection of in situ samples with the satellite pass and statistically linking these cover dens...The principles of remotely estimating grassland cover density in an alpine meadow soil from space lie in the synchronous collection of in situ samples with the satellite pass and statistically linking these cover densities to their image properties according to their geographic coordinates. The principles and procedures for quantifying grassland cover density from satellite image data were presented with an example from Qinghai Lake, China demonstrating how quantification could be made more accurate through the integrated use of remote sensing and global positioning systems (GPS). An empirical model was applied to an entire satellite image to convert pixel values into ground cover density. Satellite data based on 68 field samples was used to produce a map of ten cover densities. After calibration a strong linear regression relationship (r2 = 0.745) between pixel values on the satellite image and in situ measured grassland cover density was established with an 89% accuracy level. However, to minimize positional uncertainty of field samples, integrated use of hyperspatial satellite data and GPS could be utilized. This integration could reduce disparity in ground and space sampling intervals, and improve future quantification accuracy even more.展开更多
[Objective] To investigate the relationship between the grassland caterpillar with different grades and the structure of alpine Kobresia meadow or soil feature. [Method] A total of 10 plots （20.00 m × 20.00 m） ...[Objective] To investigate the relationship between the grassland caterpillar with different grades and the structure of alpine Kobresia meadow or soil feature. [Method] A total of 10 plots （20.00 m × 20.00 m） were chosen. In each plot, five smaller plots （5.00 m × 5.00 m） were randomly selected and six sample plots （0.25 m × 0.25 m） were then selected in each smaller plot. The biomass, vegetation height, grasslayer thickness, bare land area, soil moisture and total vegetation cover degree were determined. Data were analyzed statistically by Excel 2003 and SPSS 13.0 software. [ Result] There was a significant difference （P 〈 0.05） between the grassland caterpillars at different hazard grades and the structure of alpine Kobresia meadow or soil properties. [ Conclusion] With the increase of grassland caterpillar density, the plant community structure of alpine Kobresia meadows changes from sedge family-dominant community to the forbs-dominant community.展开更多
The dynamics of plant community and above- and belowground biomass of the different degenerative stages was researched of Kobresia hurnlis meadows of Nakchu prefecture in Tibet Autonomous Region. The results indicated...The dynamics of plant community and above- and belowground biomass of the different degenerative stages was researched of Kobresia hurnlis meadows of Nakchu prefecture in Tibet Autonomous Region. The results indicated that the aggravation of the degree of deterioration of alpine meadow is, the lower the vegetation coverage, percentage of excellent forage, and biodiversity are. The total aboveground biomass is highest in the lightly degraded stages while it is lowest in the extremely degraded stages. With the aggravation of degradation, the aboveground biomass of forbs increases while that of Cyperaceae decreases. We found that the belowground biomass was mostly distributed in the 0-10 cm soil depth in the alpine meadow with a ＂T＂-shape distribution feature, and with the acceleration of deterioration, the numbers of roots becomes less and less. Meanwhile, the above- and belowground biomass of the different degraded communities was significantly correlated（r= 0. 963）. There is an obvious positive correlation with the above- and belowground biomass in different degenerative stages, and their ratio increased with the aggravation of degradation.展开更多
基金supported by the National Basic Research Program of China (No. 2006CB400505) and the National NaturalSciences Foundation of China (Nos. 49971056 and 40171007)
文摘The principles of remotely estimating grassland cover density in an alpine meadow soil from space lie in the synchronous collection of in situ samples with the satellite pass and statistically linking these cover densities to their image properties according to their geographic coordinates. The principles and procedures for quantifying grassland cover density from satellite image data were presented with an example from Qinghai Lake, China demonstrating how quantification could be made more accurate through the integrated use of remote sensing and global positioning systems (GPS). An empirical model was applied to an entire satellite image to convert pixel values into ground cover density. Satellite data based on 68 field samples was used to produce a map of ten cover densities. After calibration a strong linear regression relationship (r2 = 0.745) between pixel values on the satellite image and in situ measured grassland cover density was established with an 89% accuracy level. However, to minimize positional uncertainty of field samples, integrated use of hyperspatial satellite data and GPS could be utilized. This integration could reduce disparity in ground and space sampling intervals, and improve future quantification accuracy even more.
基金funded by the grants from Basic Science and Research Special Fund for the State Level and Public Scientific Research Institute (Grassland Research Institute,Chinese Academy of Agricultural Sciences) and Wild Science Observation Testing Station of Alpine Meadow Grassland Resource and Ecotope of the Ministry of Agriculture
文摘[Objective] To investigate the relationship between the grassland caterpillar with different grades and the structure of alpine Kobresia meadow or soil feature. [Method] A total of 10 plots （20.00 m × 20.00 m） were chosen. In each plot, five smaller plots （5.00 m × 5.00 m） were randomly selected and six sample plots （0.25 m × 0.25 m） were then selected in each smaller plot. The biomass, vegetation height, grasslayer thickness, bare land area, soil moisture and total vegetation cover degree were determined. Data were analyzed statistically by Excel 2003 and SPSS 13.0 software. [ Result] There was a significant difference （P 〈 0.05） between the grassland caterpillars at different hazard grades and the structure of alpine Kobresia meadow or soil properties. [ Conclusion] With the increase of grassland caterpillar density, the plant community structure of alpine Kobresia meadows changes from sedge family-dominant community to the forbs-dominant community.
文摘The dynamics of plant community and above- and belowground biomass of the different degenerative stages was researched of Kobresia hurnlis meadows of Nakchu prefecture in Tibet Autonomous Region. The results indicated that the aggravation of the degree of deterioration of alpine meadow is, the lower the vegetation coverage, percentage of excellent forage, and biodiversity are. The total aboveground biomass is highest in the lightly degraded stages while it is lowest in the extremely degraded stages. With the aggravation of degradation, the aboveground biomass of forbs increases while that of Cyperaceae decreases. We found that the belowground biomass was mostly distributed in the 0-10 cm soil depth in the alpine meadow with a ＂T＂-shape distribution feature, and with the acceleration of deterioration, the numbers of roots becomes less and less. Meanwhile, the above- and belowground biomass of the different degraded communities was significantly correlated（r= 0. 963）. There is an obvious positive correlation with the above- and belowground biomass in different degenerative stages, and their ratio increased with the aggravation of degradation.
