Warming and disturbances threaten Arctic-boreal vegetation resilience
Yue Zhang, The Ohio State University, zhang.12439@buckeyemail.osu.edu
Jonathan Wang, University of Utah, jon.wang@utah.edu
Logan Berner, Northern Arizona University, logan.berner@nau.edu
Scott J. Goetz, Northern Arizona University, scott.goetz@nau.edu
Yanlan Liu, The Ohio State University, liu.9367@osu.edu (Presenter)
Arctic-boreal ecosystems have experienced extensive vegetation change over the recent decades. Rapid warming and more frequent disturbances cause large uncertainties in future vegetation distribution and carbon sink strength. A major challenge for accurately predicting Arctic-boreal vegetation change is to characterize vegetation resilience, i.e., when and where vegetation becomes vulnerable to climate fluctuations and how fast it recovers after disturbances. However, besides previous studies focusing on post-fire recovery at limited field sites, the response of resilience to climate trends and disturbances has not been systematically characterized at large scales in Arctic-boreal ecosystems. Here, we map vegetation resilience using temporal autocorrelation of greenness, a metric quantifying vegetation recovery from climate perturbations and disturbances, across the core domain of NASA Arctic-Boreal Vulnerability Experiment (ABoVE). We use a Bayesian dynamic linear model to estimate time-varying autocorrelation using submonthly Enhanced Vegetation Index from MODIS at a 250 m resolution. The results show that vegetation resilience has reduced in half of the domain, primarily in boreal forests. Notably, greenness trends did not explain resilience changes, suggesting that greening does not always enhance resilience. Instead, reduced resilience is primarily detected at locations with high summer temperatures, deep active layer, and high elevation. We further categorize resilience change before and after different land cover changes and fire disturbances. We found resilience pervasively reduced--as an early warning signal--one to five years prior to climate-induced forest losses and remained low within five years afterward. In addition, vegetation also resilience remained low in most fire-disturbed areas even five years later, suggesting limited postfire recovery. Our findings highlight warming and disturbance have been undermining vegetation resilience, especially in boreal forests, which could in turn threaten ecosystem carbon sink strength under projected climates. The derived resilience maps and the identified control factors will provide a benchmark facilitating further observational and modeling research for better prediction of Arctic-boreal vegetation dynamics.
Poster: Poster_Zhang_3-33_219_35.pdf
Associated Project(s):
Poster Location ID: 3-33
Presentation Type: Poster
Session: Poster Session 3
Session Date: Thu (May 11) 3:00-5:00 PM
CCE Program: TE