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Scientia Silvae Sinicae ›› 2009, Vol. 12 ›› Issue (6): 45-53.doi: 10.11707/j.1001-7488.20090609

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Leave Gas Exchange Characteristics of Sprout Seedlings of Two PoplarSpecies in the Irtysh River Basin，Xinjiang

Liu Hua1,2,Zang Runguo2,Jiang Xiaoheng3,Ding Yi2,Zhang Weiyin2,Bai Zhiqiang3,Guo Zhongjun3   

  1. (1.School of Forestry & Landscape Architecture，Anhui Agricultural University Hefei 230036；2.Key Laboratory of Forest Ecology and Environment，The State Forestry Administration Institute of Forest Ecology， Environment and Protection，Chinese Academy of Forestry Beijing 100091；3.Institute of Forest Ecology，Xinjiang Academy of Forestry Urumqi 830000)
  • Received:2008-03-18 Revised:1900-01-01 Online:2009-06-25 Published:2009-06-25

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Abstract:

The riparian forest along the Irtysh river watershed, Xinjiang of Northwest China is regarded as an important gene pool for plants in the family Salicaceae. The survival and development of these plants could affect the structure and functions of the natural ecosystems in the river basin. The special environmental characteristics (such as drought, high temperature, and strong light in the growing season) in the river basin area often cause stresses on growth and development of the plants. Our major objectives were: 1) to understand the influence of natural drought stress on ecophysiological characteristics of the natural sprout poplars, 2) to compare the drought resistance of the two natural poplar species in terms of the ecophysiology to explain their distribution difference. We selected three different ages of natural sprout tillers of Populus laurifolia Ledeb. and P. alba Linn. Some stomatal factors such as Gs, Ls, Pn, Tr, and WUE were measured with LI-6400 from June to August in 2006. The results showed that monthly changes of Gs for the two poplar species declined from June to August. The diurnal change curves of G s of the two popular species in three different ages were basically in the form of unimodal or bimodal. The diurnal change curve of Gsfor P. laurifolia was bimodal in June, and was unimodal in July and August. The maximum value of Gs for P. laurifolia all appeared at 11:00 OClock in the day of measurement. The diurnal change curve of Gs for P. alba was bimodal in June and July, and the maximum value of Gs in the day of measurement occurred at 11:00 OClock and 13:00 OClock, respectively. Drought resistance and photosynthesis characteristics of the two popular species were compared by using Ls value at 15:00 OClock when most stomata restriction appeared. Tr of these two species were restricted by Ls in June and July, and the restrictions to P. laurifolia was higher than that to P. alba. Pn and WUE were not affected by Ls in June and July. But in August, when the Ls value of P. laurifoliawas greater than 0.3, Pn was restricted by Ls apparently, while the leaves of P. alba were shed because of the drought stress. This study showed that in general P. laurifolia had stronger adaptability to natural drought stress than P. alba in this region. This may be one of reasons why P. laurifolia has wider distribution areas than P. alba in the Irtysh rive basin areas. We could predict from this study that P. laurifolia will be able to adapt better than P. alba to the further drought caused by both global climate change and anthropogenic water withdraw from the Irtysh river.

Key words: Irtysh river, Poplars, sprouting seedling, photosynthesis, gas exchange