Relationships among vegetation,climatic zonation,soil,and bedrock in the central White-Inyo Range,eastern California:A ground-based and remote-sensing study

摘要

To assess the effects of regional climate change using remote-sensing methods,we conducted integrated geologic,botanical,and field-radometer baseline studies on the ground in the central White-Inyo Mountains.Vegetation on contrasting geologic substrates in 58,50 X 50 m sites was studied annually in early July and in late September 1997-2001.We quantified areal abundances of plant species by using field inventories and ground-based values of te normalized-difference vegetation index (NDVI).Distributions and abundances of speciew are complex functions of microcilmate (elevation,slope,and facing direction),seasonality,soil development,bedrock lithologies,and albedo.X-ray diffraction studies demonstrate that the soils consist chiefly of in situ weathering components such as illite,montmorillonite,chlorite,quartz,carbonates,and feldspars.Soils along higher ridges contain modest amounts of wind-blown grains derived from glaciated granodioritic plutons and volcanic roof pendants of the Sierra Nevada.Light-colored limestone and dolomite support only sparse amounts of Sagebrush at any altitude,whereas this drought-tolerant species is widespread on dark argillite,quartzite,phyllite,and granitic rocks.Grasses grow luxuriantly on dark granite and quartzite,but poorly on carbonate bedrock.Trees are numerous on carbonate rocks,but are uncommon on dark granite and quartzite.higher-albedo rocks and soils retain moisture better than darker substrates and in general support greater vegetative cover and biomass.These studies provided ground control for hyperspectral data collected by ER-2 aircraft along three Airborne Visible and InfraRed Imaging Spectrometer (AVIRIS) flight lines.Because of the approx 16 m spatial resolution of the remotely sensed data,only plant communities could be mapped from AVIRIS imagery.On the basis of the dominant species,we identified the following communities:Shadscale/desert scrub;Pin-you-Juniper woodlands;Sagebrush meadows;Mountain Mahogany woodlands;Aspen woodlands;Bristlecone Pine-Limber Pine woodlands;and Alpine fell-fields.When judged by correlatio with the 50 X 50 m ground-based inventoried sites,botanical community assignments for the June 2000 flight lines achieved an accuracy of 81%;in contrast,October 1996 assignments were only 65% correct,reflecting low sun angle and senesced vegetation.