Vegetation productivity responses to drought on tribal lands in the four corners region of the Southwest USA

• Published in: Frontiers of earth science Vol. 12; no. 1; pp. 37 - 51
• Main Authors: EL-VILALY, Mohamed Abd Salam, DIDAN, Kamel, MARSH, Stuart E., VAN LEEUWEN, Willem J.D., CRIMMINS, Michael A., MUNOZ, Armando Barreto
• Format: Journal Article
• Language: English
• Published: Beijing Higher Education Press 01-03-2018; Springer Nature B.V
• Subjects: Agricultural ecosystems; Agriculture; Climate; Climate and vegetation; Climate change; Climate variability; Corners; Data; Data processing; Drought; Drought conditions; Earth and Environmental Science; Earth Sciences; Ecosystem services; Ecosystems; Erosion; Hopi; Hypersensitivity; Livestock; Monitoring systems; Navajo Nation; Normalized difference vegetative index; Precipitation; Productivity; Regression analysis; Remote monitoring; Remote sensing; Research Article; Soil; Soil erosion; Soil water; Time series; Vegetation; Vegetation index; Water resources; United States > US; remote sensing; Hopi; Navajo Nation; drought
• ISSN: 2095-0195; 2095-0209
• DOI: 10.1007/s11707-017-0646-z

For more than a decade, the Four Corners Region has faced extensive and persistent drought conditions that have impacted vegetation communities and local water resources while exacerbating soil erosion. These persistent droughts threaten ecosystem services, agriculture, and livestock activities, and expose the hypersensitivity of this region to inter-annual climate variability and change. Much of the intermountain Western United States has sparse climate and vegetation monitoring stations, making fine-scale drought assessments difficult. Remote sensing data offers the opportunity to assess the impacts of the recent droughts on vegetation productivity across these areas. Here, we propose a drought assessment approach that integrates climate and topographical data with remote sensing vegetation index time series. Multi-sensor Normalized Difference Vegetation Index (NDVI) time series data from 1989 to 2010 at 5.6 km were analyzed to characterize the vegetation productivity changes and responses to the ongoing drought. A multi-linear regression was applied to metrics of vegetation productivity derived from the NDVI time series to detect vegetation productivity, an ecosystem service proxy, and changes. The results show that around 60.13% of the study area is observing a general decline of greenness ( p<0.05), while 3.87% show an unexpected green up, with the remaining areas showing no consistent change. Vegetation in the area show a significant positive correlation with elevation and precipitation gradients. These results, while, confirming the region's vegetation decline due to drought, shed further light on the future directions and challenges to the region's already stressed ecosystems. Whereas the results provide additional insights into this isolated and vulnerable region, the drought assessment approach used in this study may be adapted for application in other regions where surface-based climate and vegetation monitoring record is spatially and temporally limited.