The spatial effects of the NDVI reconstruction in the Greater Yellowstone Ecosystem derived from the tree-ring

Authors: Hang Li*, Indiana State University, James H. Speer , Indiana State University
Topics: Biogeography, Paleoenvironmental Change, Temporal GIS
Keywords: NDVI, Tree- ring chronology, Greater Yellowstone Ecosystem Area, Temporal reconstruction
Session Type: Virtual Paper
Day: 4/9/2021
Start / End Time: 6:15 PM / 7:30 PM
Room: Virtual 30
Presentation File: No File Uploaded

Climate change is likely to cause vegetation regime shifts. The conventional research combined tree-ring width (TRW) and the normalized difference vegetation index (NDVI) using coarse resolution images to reconstruct NDVI and ignore spatial effects. Our study intended to build up an integrated model for the Greater Yellowstone Ecosystem with three sub-models, map the annual NDVI spatial distributions since 1906, and explore the spatial effects of the relationship between TRW and NDVI by using 622 Landsat satellite images and tree cores from 15 plots. The overall NDVI in 1906, 1930, and 2015 were 0.3, 0.1, and 0.25 respectively, which indicated regime shifts that could be attributed to multiple disturbance factors such as increased browsing intensity by elk along with drought. Our model performed well in our study area with alpha values less than 0.05 and less than 0.1 took up 53.97% and 71.14% of the whole area, respectively. The NDVI for the whole area and the forest both showed significant negative correlations with the annual maximum temperature (R_whole = -0.200; R_forest = -0.215). The low P values and the gap between NDVI for the whole area and forest land is because water and barren lands degrade the NDVI reconstruction. We believe that the coupling between NDVI and TRW should be a result of the single and persistent threat, which leads to the synchronous and similar reactions between the vegetation and the cambium.

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