Local-regional similarity in drylands increases during multiyear periods and in response to extreme events

Authors: PETRIE, MATTHEW - New Mexico State University; Peters, Debra; BURRUSS, N. DYLAN - New Mexico State University; JI, WENJIE - New Mexico State University; SAVOY, HEATHER - New Mexico State University

Submitted to: Ecosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2019
Publication Date: 12/5/2019
Citation: Petrie, M., Peters, D.C., Burruss, N., Ji, W., Savoy, H. 2019. Local-regional similarity in drylands increases during multiyear periods and in response to extreme events. Ecosphere. 10(12):e02939. https://doi.org/10.1002/ecs2.2939.
DOI: https://doi.org/10.1002/ecs2.2939

Interpretive Summary: In the Chihuahuan Desert, multiyear wet and dry periods and extreme PPT pulses are the most influential climatic events for vegetation. Vegetation responses are most frequently studied locally, and regional responses are often unclear. We present an observational teleconnections approach to quantify correlation between PPT and vegetation responses (as Normalized Difference Vegetation Index, NDVI) at the Jornada ARS-LTER site (JRN; 550 km2 area) with the surrounding dryland region (from 0-500 km distance; 400,000 km2 study area) as a way to understand regional similarity to locally-observed patterns. We focused on fluctuating wet and dry years (average conditions), multi-year wet or dry periods of 3-4 years, and multiyear periods that contained one or more extreme PPT pulses. Results show that spatial heterogeneity in PPT and vegetation responses is reduced in both multiyear wet and dry periods, with the largest changes during multiyear wet periods. We conclude that site-based research during multiyear periods can be extended to larger regional responses.

Technical Abstract: Climate change is predicted to impact ecosystems through altered precipitation (PPT) regimes. In the Chihuahuan Desert, multiyear wet and dry periods and extreme PPT pulses are the most influential climatic events for vegetation. Vegetation responses are most frequently studied locally, and regional responses are often unclear. We present an observational teleconnections approach to quantify correlation between PPT and vegetation responses (as Normalized Difference Vegetation Index, NDVI) at the Jornada ARS-LTER site (JRN; 550 km2 area) with the surrounding dryland region (from 0-500 km distance; 400,000 km2 study area) as a way to understand regional similarity to locally-observed patterns. We focused on fluctuating wet and dry years (average conditions), multi-year wet or dry periods of 3-4 years, and multiyear periods that contained one or more extreme PPT pulses. In all periods except those with extreme wet years, JRN PPT was highly correlated with regional PPT. Site-level correlations were with 10th - 90th percentiles in PPT at distances from 0-200 km, and from 25th - 75th percentiles from 0-500 km. In contrast, JRN NDVI was correlated with regional NDVI on average with lower percentiles than for PPT; from 10th - 65th percentiles from 0-200 km, and from 10th - 35th percentiles from 0-500 km. Local to regional NDVI correlations increased during multiyear periods to a maximum of 10th - 90th percentiles in a number of individual years. Thus, spatial heterogeneity in PPT and vegetation responses is reduced in both multiyear wet and dry periods, with the largest changes in climatic forcing and responses during multiyear wet periods. These events support greater landscape connectedness both locally and regionally, and greater correlation between local to regional PPT and vegetation response patterns. We conclude that site-based research during multiyear periods can be extended to larger regional responses, and illustrate the opportunity to enhance understanding of future PPT change through increased focus on multiyear periods.