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

Abstract

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 CO2 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.

Grassland Phenology Response to Drought in the Canadian Prairies

“…However, there are two significant advanced subtrends (1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990) (r = −0.86, p = 0.003), and 1991-2001 (r = −0.71, p = 0.014)) within this period ( Figure A3). Similar phenology variability over a long period was documented recently from the grassland ecosystems in The Ordos [74], and on the Tibetan Plateau [75], where the moisture conditions in relation to precipitation (rainfall and snowfall) played noticeable roles in governing the interannual variation in grassland phenology. Climate change has been widely accepted as the main force for shifts in vegetation phenology, and this research all suggests that moisture condition has a critical impact on vegetation growth in water-limited ecosystems [73][74][75].…”

“…Similar phenology variability over a long period was documented recently from the grassland ecosystems in The Ordos [74], and on the Tibetan Plateau [75], where the moisture conditions in relation to precipitation (rainfall and snowfall) played noticeable roles in governing the interannual variation in grassland phenology. Climate change has been widely accepted as the main force for shifts in vegetation phenology, and this research all suggests that moisture condition has a critical impact on vegetation growth in water-limited ecosystems [73][74][75]. Therefore, it is worth considering environmental factors such as water deficit in addition to temperature, when evaluating the climate-induced change in grassland phenology and predicting the future phenology of semi-arid-to-arid grassland ecosystems (e.g., the grasslands in the prairie ecozone) in relation to climate change and variability under global warming.…”

Quantifying influences of physiographic factors on temperate dryland vegetation, Northwest China

“…A possible explanation was that increased temperature triggered vegetation growth. Moreover, increased temperature also caused the decline of soil moisture, which adversely affected vegetation growth29. Furthermore, we found that the combined effects of MAP and MAT significantly enhanced the effects of temperature on greenness change ( i.e., PD (MAP ∩ MAT) >  PD (MAT)).…”

Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai–Tibetan Plateau

“…However, we found that warming had no significant effect on NEE in 2013. This result may be attributed to delayed vegetation growth in 2013 compared with 2012 and 2014, because of lower spring soil water content in 2013 (Ganjurjav, Gao, Schwartz et al., ). Coners et al.…”

“…Studies investigating warming impacts on the plateau have shown a positive effect on ecosystem C exchange in alpine meadow regions (Peng et al., ; Ganjurjav et al., ; Chen et al., ). However, our previous studies showed that drought in the growing season resulted in a periodic decrease in NEE under warming conditions in meadow regions (Ganjurjav, Gao, Schwartz et al., ). Although many studies have examined the response of this type of grassland to warming on the plateau, no warming experiments have comprehensively considered the different grassland types.…”