Tingey D T, Lee E H, Waschmann R, Johnson M G, Rygiewicz P T
US Environmental Protection Agency, Western Ecology Division, 200 SW 35th Street, Corvallis, OR 97333, USA.
New Phytol. 2006;170(1):107-18. doi: 10.1111/j.1469-8137.2006.01646.x.
We investigated the effects of elevated soil temperature and atmospheric CO2 on soil CO2 efflux (SCE) during the third and fourth years of study. We hypothesized that elevated temperature would stimulate SCE, and elevated CO2 would also stimulate SCE with the stimulation being greater at higher temperatures. The study was conducted in sun-lit controlled-environment chambers using Douglas-fir (Pseudotsuga menziesii) seedlings grown in reconstructed litter-soil systems. We used a randomized design with two soil temperature and two atmospheric CO2 treatments. The SCE was measured every 4 wk for 18 months. Neither elevated temperature nor CO2 stimulated SCE. Elevated CO2 increased the temperature sensitivity of SCE. During the winter, the relationship between SCE and soil moisture was negative but it was positive during the summer. The seasonal patterns in SCE were associated with seasonal changes in photosynthesis and above-ground plant growth. SCE acclimatized in the high-temperature treatment, probably because of a loss of labile soil carbon. Elevated CO2 treatment increased the temperature sensitivity of SCE, probably through an increase in substrate availability.
在研究的第三年和第四年，我们调查了土壤温度升高和大气二氧化碳浓度升高对土壤二氧化碳排放（SCE）的影响。我们假设温度升高会刺激SCE，二氧化碳浓度升高也会刺激SCE，且在较高温度下刺激作用更强。该研究在阳光充足的可控环境舱中进行，使用在重建的凋落物-土壤系统中生长的花旗松（Pseudotsuga menziesii）幼苗。我们采用随机设计，设置了两种土壤温度和两种大气二氧化碳处理。在18个月的时间里，每4周测量一次SCE。温度升高和二氧化碳浓度升高均未刺激SCE。二氧化碳浓度升高增加了SCE的温度敏感性。在冬季，SCE与土壤湿度呈负相关，但在夏季呈正相关。SCE的季节模式与光合作用和地上植物生长的季节变化有关。在高温处理中SCE出现了适应性变化，可能是由于不稳定土壤碳的损失。二氧化碳浓度升高处理可能通过增加底物可用性提高了SCE的温度敏感性。
