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Time Series Analysis of Phenometrics for the U.S. Great Plains Ecoregion using Satellite-derived Vegetation Indices

Authors: Hilda U. Onuoha*, Department of Geography and Geospatial Sciences, Kansas State University, Manhattan, Kansas, USA, J.M. Shawn Hutchinson, Department of Geography and Geospatial Sciences, Kansas State University, Manhattan, Kansas, USA
Topics: Environment, Land Use, Spatial Analysis & Modeling
Keywords: Great Plains, MODIS, time series, Phenology, NDVI, grasslands
Session Type: Paper
Day: 4/6/2020
Start / End Time: 4:40 PM / 5:55 PM
Room: Virtual Track 1
Presentation File: No File Uploaded


Grasslands are one of the largest terrestrial ecosystems in the world. They are one of the most biodiverse and productive terrestrial biomes but receive very low levels of protection. The temperate grasslands in the United States are one of the most threatened grassland ecosystems with almost 96% of the historical extent lost. In the bid to understand the dynamics of grassland in the Great Plains ecoregion of the United States, I performed a time-series analysis of Moderate Resolution Imaging Spectrometer (MODIS) 16-day maximum value composite normalized difference vegetation index (NDVI) (MOD13Q1 Collection 6) to explore differences in vegetation phenology and to assess long-term trends in grassland vegetation greenness across the region. Using the program TIMESAT to extract key measures of vegetation phenological development from 2001 to 2017. Phenometrics of interest included (1) season length, (2) start of growing season, (3) end of growing season, (4) middle of growing season, (5) maximum NDVI value, (6) small integral, (7) left derivative, and (8) right derivative. I also carried out analyses to determine the significance of spatiotemporal differences in grassland phenology across the Great Plains. This is a prerequisite step for future analyses seeking to quantify the influence of climate and soils, along with key regional anthropogenic factors such as fire, on shaping long-term vegetation dynamics and the role of grasslands in providing essential ecosystem services.

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