杨树—小麦复合系统对作物冠层CO_2含量的影响

Effects of Poplar-wheat Multiplex System on the Atmospheric CO_2 Concentration above the Crop Canopy

以单作小麦系统(GK)为对照，试验研究中国黄淮海平原农区杨树一小麦(简称“复合系统”)对作物冠层GO2含量的影响作用，旨在为进一步补充与完善农林复合系统生态效应内容，以期能为农区发展农林复合系统提供一定的理论依据。结果表明：小麦拔节～乳熟期间，间作系统内小麦冠层上方0．5m处晴天白天GO2含量比GK约低7．53％，这种差异程度随日期的延续呈逐渐增大趋势，拔节期时仅为4．47％，到扬花期和乳熟期时，分别增至7．48％、11．87％。白天日内各时刻间作系统GO2含量均低于GK，且中午前后的差异程度高于早、晚时刻，但日变化规律二者间基本一致。作物冠层附近的GO2含量随距林带距离的变化呈W型分布趋势，即靠近林带处CO2含量要高于间作系统中心处。

Aiming at further supplying and perfecting the contents of ecological effect for agroforest ecosystem and providing a theoretical basis for farm production in d eveloping agroforest ecosystem, experiments were conducted in Huanghe, Huaihe and Haihe plain in China to study the effects of poplar-wheat multiplex system o n the atmospheric CO_2 concentrations by using the wheat monoculture system as control (CK). The results are as follows: during the period from wheat jointing to ripening stage, the daytime CO_2 concentration at 0.5m above the wheat ca nopy in the intercropping system in a clear day was about 7.53% lower than that in the CK; the difference tended to increase with the prolonging of time, from 4.47% during the jointing stage to 7.48% and 11.87% during flowering and ripenin g stage respectively; the daytime CO_2 concentration was always lower in the in tercropping system than in the CK and the difference was larger at noon than in the morning and the evening, however the diurnal variational patterns of CO_2 concentration were almost the same in the two systems. The CO_2 concentration n ear wheat canopy changed with the distance to the tree belts in a W shape, refl ecting that the CO_2 concentration was higher near tree belts than in the cente r of the intercropping system.