Journal of Plant Ecology ›› 2021, Vol. 14 ›› Issue (4): 591-604.DOI: 10.1093/jpe/rtab015

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  • 收稿日期:2020-08-18 修回日期:2020-10-21 接受日期:2021-01-18 出版日期:2021-08-01 发布日期:2021-04-13

Nutrient resorption and stoichiometric responses of poplar (Populus deltoids) plantations to N addition in a coastal region of eastern China

Dalong Jiang1, Qian Li2, Qinghong Geng1, Menghua Zhang1, Chonghua Xu1, Guoqing Hu3, Caiqin Shen4, Honghua Ruan1 and Xia Xu1, *   

  1. 1 Department of Ecology, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China, 2 Advanced Analysis and Testing Center, Nanjing Forestry University, Nanjing 210037, China, 3 College of Resources and Environment, Shandong Agricultural University, Tai’an 271018, China, 4 Dongtai Forest Farm, Yancheng 224200, China

    *Corresponding author. E-mail: xuxia.1982@yahoo.com
  • Received:2020-08-18 Revised:2020-10-21 Accepted:2021-01-18 Online:2021-08-01 Published:2021-04-13

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摘要： 中国东部沿海杨树人工林养分重吸收和化学计量对氮添加的响应
叶片养分重吸收对土壤养分的变化很敏感。然而，我们尚不清楚氮沉降如何影响植物大量元素重吸收率。杨树(Populus deltoids)是世界上栽培最广泛的阔叶树种之一。本文研究了在氮添加条件下，杨树重吸收率及其化学计量比的规律和主要驱动因素。通过一个4年的氮添加实验，我们探究中国东部沿海两个林分(8和12年)杨树人工林重吸收率及其化学计量比对氮添加的响应。我们测定了在一系列氮添加浓度水平(0、50、100、150、300 kg N ha−1 yr−1)下，土壤和叶片(包括绿叶和落叶)中氮、磷、钾、钙、镁的浓度。研究结果表明，除钙元素重吸收率和钙、镁元素重吸收率化学计量比外，氮添加对两个林分大量元素重吸收率及其化学计量比都没有显著影响。氮、磷重吸收率尺度斜率在不同氮添加水平下均小于1，表明氮添加条件下，氮、磷元素重吸收率解耦。养分重吸收率与绿叶中养分含量显著正相关，表明重吸收主要受到绿叶养分调控。我们的研究结果为中国东部沿海地区12年生杨树人工林的生长受氮限制提供了直接证据。

关键词: 养分重吸收, 氮添加, 化学计量, 大量元素, 绿叶养分, 杨树人工林

Abstract:

Aims

Leaf nutrient resorption is sensitive to changes in soil nutrients. However, the effects of N deposition on nutrient resorption efficiency (NuRE) in plant macro-nutrients remain unclear. Poplar (Populus deltoids) is one of the most extensively cultivated hardwood species worldwide. We explored general patterns and dominant drivers of NuRE and stoichiometry of poplar plantations in response to N addition.

Methods

We conducted a 4-year N-addition experiment to explore NuRE and stoichiometric responses to N addition in two poplar (P. deltoids) plantations (8- and 12-year-old stands) in a coastal region of eastern China. We measured soil and foliar (green and senesced leaves) concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) for a series of N addition treatments including N0 (0 kg N ha−1 yr−1), N1 (50 kg N ha−1 yr−1), N2 (100 kg N ha−1 yr−1), N3 (150 kg N ha−1 yr−1) and N4 (300 kg N ha−1 yr−1).

Important Findings

Consistent for (both) 8- and 12-year-old stands, N addition did not affect the NuRE and stoichiometry (with the exception of CaRE and CaRE:MgRE ratio). N resorption efficiency–P resorption efficiency (NRE–PRE) scaling slopes were consistently less than 1.0 under N addition. These results suggest that NRE generally decouples from PRE within each N treatment. Moreover, these results point to robust control of green leaf nutritional status on nutrient resorption processes as indicated by the positive relationships between NuRE and green leaf nutrient concentrations. Our findings provided a direct evidence that growth in 12-year-old poplar plantations was N-limited in the coastal region of eastern China.

Key words: nutrient resorption efficiency, N addition, stoichiometry, macro-nutrient, green leaf nutrients, poplar plantation

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