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Key message <p>N addition positively affected the growth of <i>C</i>.<i> pachystachya</i> (shade-intolerant) in the sun but not in the shade, while the growth of <i>C</i>. <i>estrellensis</i> (shade-tolerant) wasn’t affected.</p> Abstract <p>The Brazilian Atlantic Forest is a highly biodiverse and threatened ecosystem, subjected to intense deforestation and N deposition levels that may exceed the critical N load supported by this ecosystem. The objective of this study was to evaluate in green house conditions how 10 weekly applications of N (28&#xa0;kg N&#xa0;ha<sup>−</sup>) affects the gas exchange, the amino acid and protein concentrations in the tissues, and the growth of seedlings two tree species: <i>Cecropia pachystachya</i> (Urticaceae; shade-intolerant) and <i>Cariniana estrellensis</i> (Lecythidaceae; shade-tolerant). Plant responses to N addition were compared on sun and on shade. While <i>Cecropia pachystachya</i> improved the total plant dry mass and the relative growth rate with N addition in the sun, but not in the shade, <i>C. estrellensis</i> increased the stomatal conductance, net photosynthesis, and instantaneous carboxylation efficiency in the shade, although without any change on the plant total biomass. The results of the study indicate that the deposition of n can have differential effects on different species.</p>

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N deposition and light availability impact on the growth and physiology of seedlings of a shade-intolerant and a shade-tolerant tropical forest tree species

  • 期刊论文

  • 发表日期：

    2025年7月10日

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  • João Pedro Batista Fernandes Cunha,
  • José Antonio Pimenta,
  • José Marcelo Domingues Torezan,
  • Halley Caixeta de Oliveira,
  • Renata Stolf-Moreira

摘要

Key message

N addition positively affected the growth of C. pachystachya (shade-intolerant) in the sun but not in the shade, while the growth of C. estrellensis (shade-tolerant) wasn’t affected.

Abstract

The Brazilian Atlantic Forest is a highly biodiverse and threatened ecosystem, subjected to intense deforestation and N deposition levels that may exceed the critical N load supported by this ecosystem. The objective of this study was to evaluate in green house conditions how 10 weekly applications of N (28 kg N ha−) affects the gas exchange, the amino acid and protein concentrations in the tissues, and the growth of seedlings two tree species: Cecropia pachystachya (Urticaceae; shade-intolerant) and Cariniana estrellensis (Lecythidaceae; shade-tolerant). Plant responses to N addition were compared on sun and on shade. While Cecropia pachystachya improved the total plant dry mass and the relative growth rate with N addition in the sun, but not in the shade, C. estrellensis increased the stomatal conductance, net photosynthesis, and instantaneous carboxylation efficiency in the shade, although without any change on the plant total biomass. The results of the study indicate that the deposition of n can have differential effects on different species.