Zha T S, Kellomaki S, Wang K Y
Faculty of Forestry, University of Joensuu, FIN-80101 Joensuu, Finland.
Ann Bot. 2003 Jul;92(1):89-96. doi: 10.1093/aob/mcg118. Epub 2003 May 21.
Sixteen 20-year-old Scots pine (Pinus sylvestris L.) trees growing in the field were enclosed for 4 years in environment-controlled chambers that maintained: (1) ambient conditions (CON); (2) elevated atmospheric CO2 concentration (ambient + 350 micro mol mol-1; EC); (3) elevated temperature (ambient +2-6 degrees C; ET); or (4) elevated CO2 and elevated temperature (ECT). The dark respiration rates of 1-year-old shoots, from which needles had been partly removed, were measured over the growing season in the fourth year. In all treatments, the temperature coefficient of respiration, Q10, changed with season, being smaller during the growing season than at other times. Respiration rate varied diurnally and seasonally with temperature, being highest around mid-summer and declining gradually thereafter. When measurements were made at the temperature of the chamber, respiration rates were reduced by the EC treatment relative to CON, but were increased by ET and ECT treatments. However, respiration rates at a reference temperature of 15 degrees C were reduced by ET and ECT treatments, reflecting a decreased capacity for respiration at warmer temperatures (negative acclimation). The interaction between season and treatment was not significant. Growth respiration did not differ between treatments, but maintenance respiration did, and the differences in mean daily respiration rate between the treatments were attributable to the maintenance component. We conclude that maintenance respiration should be considered when modelling respiratory responses to elevated CO2 and elevated temperature, and that increased atmospheric temperature is more important than increasing CO2 when assessing the carbon budget of pine forests under conditions of climate change.
16棵生长在野外的20年生欧洲赤松（Pinus sylvestris L.）被置于环境控制室内4年，这些室内维持着以下条件：（1）环境条件（CON）；（2）大气CO₂浓度升高（环境浓度 + 350微摩尔/摩尔；EC）；（3）温度升高（环境温度 +2 - 6摄氏度；ET）；或（4）CO₂浓度升高和温度升高（ECT）。在第四年的生长季节，测量了部分去除针叶的1年生嫩枝的暗呼吸速率。在所有处理中，呼吸作用的温度系数Q₁₀随季节变化，在生长季节比其他时期小。呼吸速率随温度呈昼夜变化和季节变化，在仲夏左右最高，此后逐渐下降。当在室内温度下进行测量时，相对于CON，EC处理降低了呼吸速率，但ET和ECT处理提高了呼吸速率。然而，在15摄氏度的参考温度下，ET和ECT处理降低了呼吸速率，这反映了在较高温度下呼吸能力的下降（负驯化）。季节与处理之间的相互作用不显著。生长呼吸在各处理间没有差异，但维持呼吸有差异，各处理间平均每日呼吸速率的差异归因于维持部分。我们得出结论，在模拟对CO₂浓度升高和温度升高的呼吸响应时应考虑维持呼吸，并且在评估气候变化条件下松林的碳收支时，大气温度升高比CO₂浓度升高更重要。
