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Bulletin of Botanical Research ›› 2019, Vol. 39 ›› Issue (3): 407-420.doi: 10.7525/j.issn.1673-5102.2019.03.011

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Response of Ecological Stoichiometric Characteristics and Photosynthetic Characteristics of Plant Leaves to Long-term N Deposition in Natural Secondary Forest

WAN Xue-Bing, WANG Qing-Gui, YAN Guo-Yong, XING Ya-Juan   

  1. College of Agricultural Resource and Environment, Heilongjiang University, Harbin 150080
  • Received:2018-10-16 Online:2019-05-05 Published:2019-05-11
  • Supported by:
    Natural Science Foundation of China(41773075,41575137,31370494,31170421)

Abstract: Three nitrogen(N) concentration gradients were set up in Experimental Forest Farm of Lushuihe Forestry Bureau in Fusong County, Jilin Province, including control(CK 0 g·N·m-2·a-1), low nitrogen(LN 2.5 g·N·m-2·a-1) and high nitrogen(HN 5.0 g·N·m-2·a-1), to study the effects of N deposition on the stoichiometric characteristics, nutrient reuptake and changes of photosynthetic characteristics of leaves of birch(Betula platyphylla) and poplar(Populus davidiana), a pioneer tree in natural secondary forest, and the relationship between the characters. The results showed that:(1)Under the simulated N deposition, the C content of the fresh leaves of birch and poplar showed no significant influence compared with that of the control group, and the N and P contents of the fresh leaves of poplar were significantly reduced by LN treatment(P<0.05), and C:N, C:P and N:P were significantly increased(P<0.05). HN treatment significantly increased N content and N:P in birch leaf and significantly decreased C:N(P<0.05). (2)The resorption efficiency of leaves N and P of birch and poplar decreased significantly in the treatment of LN(P<0.05) and were all negative. There was a significant positive correlation between N and P resorption efficiency(P<0.05), and a significant negative correlation between C:N and N resorption efficiency(P<0.05). (3)N addition can improve the nitrogen photosynthetic efficiency(PNUE) and net photosynthetic rate(Pn) of two kinds of trees(P<0.05), leaf dry matter to leaf area(LMA) of birch and poplar showed a significant negative correlation with N content(P<0.05), and there was significant positive correlation between Pn and PNUE(P<0.05). The N content of birch leaf was significantly positively correlated with Pn and PNUE(P<0.05). The results showed that N and P in birch and poplar leaves were enriched in the growing season, and soil nutrient and exogenous N could be used to absorb and promote the growth of trees quickly, without the need to absorb nutrients from litters leaves. N addition can enhance the photosynthetic performance of the leaves of birch and poplar, thus promoting the plant nutrient absorption and leaf development. HN deposition can promote the growth of natural secondary forest in Changbai Mountains.

Key words: nitrogen deposition, characteristics of ecological stoichiometry, nutrient resorption efficiency, photosynthetic characteristics, natural secondary forest

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