State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Xiangshan, Beijing, China.
PLoS One. 2012;7(2):e32088. doi: 10.1371/journal.pone.0032088. Epub 2012 Feb 16.
The longer growing season under climate warming has served as a crucial mechanism for the enhancement of terrestrial carbon (C) sink over the past decades. A better understanding of this mechanism is critical for projection of changes in C cycling of terrestrial ecosystems.
METHODOLOGY/PRINCIPAL FINDINGS: A 4-year field experiment with day and night warming was conducted to examine the responses of plant phenology and their influences on plant coverage and ecosystem C cycling in a temperate steppe in northern China. Greater phenological responses were observed under night than day warming. Both day and night warming prolonged the growing season by advancing phenology of early-blooming species but without changing that of late-blooming species. However, no warming response of vegetation coverage was found for any of the eight species. The variances in species-level coverage and ecosystem C fluxes under different treatments were positively dependent upon the accumulated precipitation within phenological duration but not the length of phenological duration.
CONCLUSIONS/SIGNIFICANCE: These plants' phenology is more sensitive to night than day warming, and the warming effects on ecosystem C exchange via shifting plant phenology could be mediated by precipitation patterns in semi-arid grasslands.
在过去几十年中，气候变暖导致的生长季延长是增强陆地碳（C）汇的关键机制。更好地理解这一机制对于预测陆地生态系统的碳循环变化至关重要。
方法/主要发现：本研究在中国北方的温带草原进行了为期 4 年的日夜间增温野外实验，以检验植物物候对植物覆盖度和生态系统 C 循环的影响。夜间增温比日间增温引起更大的物候响应。日夜间增温都通过提前早期开花物种的物候来延长生长季，但不改变晚期开花物种的物候。然而，在八种物种中，没有发现任何一种植被覆盖度有增温响应。不同处理下物种水平覆盖度和生态系统 C 通量的方差与物候持续时间内的累积降水量呈正相关，而与物候持续时间的长度无关。
结论/意义：这些植物的物候对夜间增温比对日间增温更敏感，通过改变植物物候来影响生态系统 C 交换的增温效应可能受到半干旱草原降水模式的调节。
