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Pak. J. Bot., 44(3): 939-948, 2012. |
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Updated: 05-05-12 | ||||
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EFFECTS OF SLOPE ASPECTS AND STAND AGE ON THE PHOTOSYNTHETIC AND PHYSIOLOGICAL CHARACTERISTICS OF THE BLACK LOCUST (ROBINIA PSEUDOACACIA L.) ON THE LOESS PLATEAU
YUAN ZHENG1, 2, ZHONG ZHAO2*, HUI ZHOU2 AND JING-JING ZHOU2
Abstract: To investigate the effects of slope aspects and stand age on the photosynthetic and physiological characteristics of black locusts on the Loess Plateau, the responses of photosynthesis and physiology to light radiation and CO2 concentration between juvenile (6-year-old) and mature (18-year-old) black locusts located on the sunny (southeast-facing) and shady (northwest-facing) slopes were compared and analyzed. Mature black locusts on the shady slopes present significantly higher Amax, Vcmax, AQY, ACE, Rd, Rp, Rubisco, LSP but lower Jmax/Vcmax, LCP, CSP than those on the sunny slopes, and the responses of E and WUE to PAR and [Ci] show considerable discrepancies at different slope aspects, which is mainly due to the variations in the microclimatic conditions between the sunny and shady slope aspects. Juvenile black locusts have significantly greater Amax, Jmax, Jmax/Vcmax, Rd, LCP, CCP, CSP, E but lower AQY, WUE compared to mature trees, which is likely associated with age-related differences in physiological activities. It is concluded that the mature and juvenile black locusts perform various effective acclimations of photosynthetic physiology to different slope conditions on the Loess Plateau.
1College of Forestry, Southwest Forestry University, Kunming, Yunnan 650224, P. R. China 2Key Laboratory of Environment and Ecology in Western China of Ministry of Education, College of Forestry, Northwest A & F University, Yangling, Shaanxi 712100, P. R. China *Correspondence: E-mail: zhaozh@nwsuaf.edu.cn; Tel: +86 29 87082801 |
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