Chin J Plant Ecol ›› 2018, Vol. 42 ›› Issue (9): 926-937.DOI: 10.17521/cjpe.2018.0167

• Review • Previous Articles     Next Articles

Responses of nitrogen and phosphorus resorption from leaves and branches to long-term nitrogen deposition in a Chinese fir plantation

SHEN Fang-Fang1,2,LI Yan-Yan1,2,LIU Wen-Fei2,DUAN Hong-Lang2,FAN Hou-Bao2,*(),HU Liang2,MENG Qing-Yin3   

  1. 1School of Forestry, Jiangxi Agricultural University, Jiangxi Key Laboratory of Silviculture, Nanchang 330045, China
    2Institute of Ecology and Environmental Science, Nanchang Institute of Technology, Jiangxi Key Laboratory for Restoration of Degraded Ecosystems and Watershed Ecohydrology, Nanchang 330099, China
    3Guanzhuang National Forest Farm of Shaxian, Sha Xian, Fujian 365503, China
  • Received:2018-07-16 Revised:2018-09-10 Online:2018-09-20 Published:2019-01-15
  • Contact: Hou-Bao FAN
  • Supported by:
    Supported by the National Natural Science Foundation of China.(31360175);Supported by the National Natural Science Foundation of China.(31570444);the Gan-Po 555 Talent Project, and the Jiangxi Provincial Fund for Academic and Technical Leadership of Major Disciplines.(20162BCB22021)

Abstract:

Aims Our objectives were to investigate differences in nutrient resorption between different plant organs (leaf and branch), among plants with different life spans (one-year old, two-year old and senesced), and under different duration of nitrogen (N) deposition treatments in a Chinese fir (Cunninghamia lanceolata) plantation.

Methods The long-term N deposition experiment was conducted in a 12-year-old fir plantation of subtropical China. N deposition treatment was initiated in January 2004 until now, up-going 14 years. N deposition were designed at 4 levels of 0, 60, 120, and 240 kg·hm -2·a -1, indicated as N0, N1, N2, and N3, respectively, with 3 replicates for each treatment. The solution of CO(NH2)2was sprayed on the forest floor each month. In the study, we measured N and phosphorus (P) concentrations and analyzed the pattern of nutrient resorption of mature and senescing leaves and branches. The different responses of needles N and P resorption after 7- and 14-year N deposition treatments were also compared.

Important findings After 14 years of N deposition, (1) during the senescing process, leaf and branch C, N, and P content gradually decreased with increasing treatment duration, with higher content in leaf than in branch. N content decreased in the order of one-year old green leaf > two-year old green leaf > senescent leaf > one-year old living branch > two-year old living branch > senescent branch, and N3 > N2 > N1 > N0, with C:N showing the opposite trend. Senescent organs had higher C:N, N:P, and C:P than mature living organs. N deposition increased N, N:P, and C:P of mature living organs (except for the two-year old green leaf), while decreased P and C:N. (2) N resorption efficiency (REN) and P resorption efficiency (REP) of leaves and branches decreased gradually with increasing life span. REP was typically higher in leaf and branch than REN. Leaf had lower REN (28.12%) than branch (30.00%), but higher REP (45.82%) than branch (30.42%). A highly significant linear correlation existed between N:P and REN:REP in leaves and branches. (3) REN decreased but REP increased with the treatment duration of N deposition. The longer experimental duration (14 years) reduced REN by 9.85%, 3.17%, 11.71% under N1, N2, and N3 treatments, respectively, and increased REP by 71.98%, 42.25%, 9.60%, respectively, than the shorter treatment duration (7 years). In summary, the responses of essential nutrients resorption efficiency for different plant organs and life span varied with the levels and duration of N deposition treatment. REN:REP in leaf and branch were mostly driven by N:P of leaf and branch. The results highlight that nutrients resorption is significantly influenced by long-term N deposition.

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Key words: nutrient resorption efficiency, ecological stoichiometry, Cunninghamia lanceolata plantation, long-term nitrogen deposition