Warming diminishes the stability of primary productivity in global grass- and forb-dominated ecosystems

Global warming has induced increases in productivity in open, grass- and forb-dominated (OGFD) ecosystems. However, little attention has been given to the temporal stability of productivity responses to global warming. We show that the stability of productivity in OGFD ecosystems decreased significantly over the past 40 years. Using the satellite-derived normalized difference vegetation index (NDVI) data from the Global Inventory Modelling and Mapping Studies (GIMMS) group, we analyzed global patterns of the stability in productivity among OGFD ecosystems. We found that the global mean stability of NDVI-based productivity estimates significantly decreased from 1982 to 2015. Comparing different trends, we found that stability decreased by 36%, and increased by 27% of the total area of OGFD ecosystems. The stability of productivity in OGFD ecosystems decreased in the northern hemisphere, especially in the Mongolian plateau and Eurasian steppe. In contrast, stability increased significantly in the southern hemisphere. Increases in both mean annual temperature and annual temperature variability were correlated with decreases in the stability of productivity in the northern hemisphere. Although the productivity of OGFD ecosystems has generally increased with warming, the stability of production has decreased. OGFD ecosystems, particularly northern hemisphere systems with low baseline productivity may be vulnerable to the loss of grazing potential and grazing consistency in the warmer future. These observations highlight the need for adaptation strategies for animal husbandry to respond to variability in productivity and reduce the negative impact of climate change on grazed ecosystems. © 2022 The Author(s). Published by IOP Publishing Ltd.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Complex responses of spring vegetation growth to climate in a moisture-limited alpine meadow

Since 2000, the phenology has advanced in some years and at some locations on the Qinghai-Tibetan Plateau, whereas it has been delayed in others. To understand the variations in spring vegetation growth in response to climate, we conducted both regional and experimental studies on the central Qinghai-Tibetan Plateau. We used the normalized difference vegetation index to identify correlations between climate and phenological greening, and found that greening correlated negatively with winter-spring time precipitation, but not with temperature. We used open top chambers to induce warming in an alpine meadow ecosystem from 2012 to 2014. Our results showed that in the early growing season, plant growth (represented by the net ecosystem CO(2) exchange, NEE) was lower in the warmed plots than in the control plots. Late-season plant growth increased with warming relative to that under control conditions. These data suggest that the response of plant growth to warming is complex and non-intuitive in this system. Our results are consistent with the hypothesis that moisture limitation increases in early spring as temperature increases. The effects of moisture limitation on plant growth with increasing temperatures will have important ramifications for grazers in this system