Vegetation Responses to 2012–2016 Drought in Northern and Southern California

Abstract

The prolonged 2012–2016 California drought has raised many issues including concerns over reduced vegetation health. Drought impacts are complicated by geographical differences in hydroclimatic variability due to a climatic dipole influenced by the Pacific. Analysis of MODIS‐derived Normalized Difference Vegetation Index and self‐calibrated Palmer Drought Severity Index from 2000 to 2018 reveals differences in drought and vegetation responses in Northern versus Southern California (NorCal vs SoCal, see definition in section ). The greatest declines in Normalized Difference Vegetation Index were focused in the SoCal, while NorCal appears not severely affected thus far. It appears that both the strength of drought and the sensitivity of the vegetation to drought are larger in SoCal. The exacerbated aridity in SoCal is a trend extending throughout the past and present century. The spatial differences in hydroclimatology and vegetation responses are important considerations for statewide climate change adaptation—with SoCal potentially facing greater challenges.

Revisiting assessments of ecosystem drought recovery

“…Reliable ecosystem production data are required in future analysis. Results in regions with rugged topography could be biased, because aggregating data sets to the coarser spatial resolution can mask some information in these regions (Dong et al 2019). Our estimates of drought recovery time can be biased by anthropogenic activities and the possible shifts in species composition (Engelbrecht et al 2007, Tong et al 2018.…”

“…The generally higher temperature and solar radiation during drought periods can even increase NDVI in temperature-and/or radiation limited regions. For instance, Dong et al (2019) found NDVI increase at high latitudes and high elevations of California during the 2012-2016 drought. Similarly, the negative GPP-DSI correlations were found in the tropics and high latitudes ( figure S2(a)).…”

“…Similarly, the negative GPP-DSI correlations were found in the tropics and high latitudes ( figure S2(a)). NDVI may also not be able to capture drought-induced tree mortality if the mortality events event exposes a green understory (Dong et al 2019). Further, in the tropics and high latitudes or elevations, satellite-based vegetation greenness are affected by cloud, aerosol contamination and snow (Beck et al 2006, Hilker et al 2014, Zhou et al 2014.…”

A New Coupled Modeling Approach to Simulate Terrestrial Water Storage in Southern California

“…The year 2012 signaled the start of a steady decline in TWS for both aquifer systems, which continued until the end of the simulation. This decline was associated with a long drought observed in Southern California [24,25]. During those years, precipitation is well below the climatological averages throughout the region (Figures 3b and 4b).…”

Quantifying Drought Sensitivity of Mediterranean Climate Vegetation to Recent Warming: A Case Study in Southern California

“…An analysis of the role of elevated temperatures associated with greenhouse gases in contributing to the severity of the drought concluded that there has been a significant imprint of anthropogenic climate change in producing drought [16]. The recent Californian drought cannot be viewed in isolation but, instead, as occurring in the context of a longer-term trajectory towards warmer and more arid conditions over the U.S. Southwest and Southern California over the past century [17][18][19][20]. Since entering the 21st century, Southern California has experienced three prolonged droughts (i.e., 2002-2003, 2007-2009, and 2012-2016).…”