Impacts of enhanced nitrogen deposition and soil acidification on biomass production and nitrogen leaching in Chinese fir plantations
2012
Blanco Vaca, Juan Antonio | Wei, Xiaohua | Jiang, Hong | Jie, Cheng-Yue | Xin, Zan-Hong | Ciencias del Medio Natural | Natura Ingurunearen Zientziak
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Afficher plus [+] Moins [-]Atmospheric pollution levels in China are increasing quickly. Experience from other polluted regions shows that tree growth could be affected, but long-term effects of N deposition and soil acidification on Chinese forests remain mostly unknown. Soil acidification and N deposition were simulated for Chinese fir plantations in Southeast China. A factorial experiment combined four levels of rain pHs (2.5, 4.0, 5.6 and 7.0), four N deposition rates (1, 7.5, 15 and 30 kg N ha-1 y-1) and two site qualities (poor and rich sites), managed for 3 consecutive 20-year rotations. Results indicate atmospheric pollution effects are not immediate, but after 1 to 2 rotations soil acidification effects could reduce ecosystem C pools significantly (-25% and -11% in poor and rich sites, respectively). N deposition rates above 15 kg N ha-1 y-1 could offset some of the negative effects of soil acidification and led to more ecosystem C (19 and 28 Mg C ha-1 more in poor and rich sites than in low N deposition). However, at high N deposition rates (>15 kg N ha-1 y-1), N leaching losses could greatly increase, reaching 75 kg N ha-1 y-1. Moderate N deposition could increase tree biomass production and soil organic mass, resulting in increased ecosystem C, but these gains could be associated to important N leaching. Atmospheric pollution could also result in the long-term in nutrient imbalances and additional ecological issues (i.e. biodiversity loss, eutrophication, etc.) not studied here.
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