State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing 100093, China.
Sci Total Environ. 2010 Jun 15;408(14):2807-16. doi: 10.1016/j.scitotenv.2010.03.016. Epub 2010 Apr 20.
One feature of climate warming is that increases in daily minimum temperature are greater than those in daily maximum temperature. Changes in soil microclimate in response to the asymmetrically diurnal warming scenarios can help to explain responses of ecosystem processes. In the present study, we examined the impacts of day, night, and continuous warming on soil microclimate in a temperate steppe in northern China. Our results showed that day, night, and continuous warming (approximately 13Wm(-2) with constant power mode) significantly increased daily mean soil temperature at 10cm depth by 0.71, 0.78, and 1.71 degrees C, respectively. Night warming caused greater increases in nighttime mean and daily minimum soil temperatures (0.74 and 0.99 degrees C) than day warming did (0.60 and 0.66 degrees C). However, there were no differences in the increases in daytime mean and daily maximum soil temperature between day (0.81 and 1.13 degrees C) and night (0.81 and 1.10 degrees C) warming. The differential effects of day and night warming on soil temperature varied with environmental factors, including photosynthetic active radiation, vapor-pressure deficit, and wind speed. When compared with the effect of continuous warming on soil temperature, the summed effects of day and night warming were lower during daytime, but greater at night, thus leading to equality at daily scale. Mean volumetric soil moisture at the depth of 0-40cm significantly decreased under continuous warming in both 2006 (1.44 V/V%) and 2007 (0.76 V/V%). Day warming significantly reduced volumetric soil moisture only in 2006, whereas night warming had no effect on volumetric soil moisture in both 2006 and 2007. Given the different diurnal warming patterns and variability of environmental factors among ecosystems, these results highlight the importance of incorporating the differential impacts of day and night warming on soil microclimate into the predictions of terrestrial ecosystem responses to climate warming.
气候变暖的一个特点是，日最低温度的上升幅度大于日最高温度。土壤微气候对非对称日升温情景的响应变化可以帮助解释生态系统过程的响应。本研究考察了日、夜和连续升温对中国北方温带草原土壤微气候的影响。结果表明，日、夜和连续升温（以恒定功率模式约为 13Wm(-2)）分别显著增加了 10cm 深度日平均土壤温度 0.71、0.78 和 1.71°C。夜间升温导致夜间平均和日最低土壤温度的增加大于白天升温（分别为 0.74 和 0.99°C）。然而，日（0.81 和 1.13°C）和夜（0.81 和 1.10°C）升温对白天平均和日最高土壤温度的增加没有差异。日和夜升温对土壤温度的差异影响随环境因素而变化，包括光合有效辐射、水汽压亏缺和风速。与连续升温对土壤温度的影响相比，日和夜升温的总和效应在白天较低，但在夜间较高，因此在日尺度上达到平衡。2006 年（1.44 V/V%）和 2007 年（0.76 V/V%），连续升温下 0-40cm 深度的平均体积土壤湿度显著降低。日升温仅在 2006 年显著降低了土壤体积湿度，而夜升温在 2006 年和 2007 年对土壤体积湿度均无影响。鉴于不同的日升温模式和生态系统中环境因素的可变性，这些结果强调了将日和夜升温对土壤微气候的不同影响纳入陆地生态系统对气候变暖响应预测的重要性。
