Impacts of enhanced nitrogen deposition and soil acidification on biomass production and nitrogen leaching in Chinese fir plantations

Abstract

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 (Cunninghamia lanceolata (Lamb.) Hook.) plantations managed for three consecutive 20-year rotations in southeastern China. A factorial experiment combined four rain pH levels (2.5, 4.0, 5.6, and 7.0), four N deposition rates (1, 7.5, 15, and 30 kg N·ha -1 ·year -1 ), and two site qualities (poor and rich). Results indicate that atmospheric pollution effects are not immediate, but after one to two 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 ·year -1 could offset some of the negative effects of soil acidification and lead to more ecosystem C (19 and 28 Mg C·ha -1 more in poor and rich sites, respectively, than in low N deposition). However, at high N deposition rates (>15 kg N·ha -1 ·year -1 ), N leaching losses could greatly increase, reaching 75 kg N·ha -1 ·year -1 . Moderate N deposition could increase tree biomass production and soil organic mass, resulting in increased ecosystem C, but these gains could be associated with 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.Résumé : Les niveaux de pollution atmosphérique augmentent rapidement en Chine. L'expérience d'autres régions aux prises avec la pollution montre que la croissance des arbres pourrait être ralentie mais les effets à long terme des dépôts azotés (N) et de l'acidification des sols dans les forêts chinoises sont pratiquement inconnus. L'acidification du sol et les dépôts de N ont été simulés dans des plantations de sapin de Chine (Cunninghamia lanceolata (Lamb.) Hook.) aménagées pendant trois rotations consécutives d'une durée de 20 ans dans le sud-est de la Chine. Une expérience factorielle a combiné quatre niveaux de pluie acide (pH 2,5, 4,0, 5,6 et 7,0), quatre taux de déposition de N (1, 7,5, 15 et 30 kg N·ha -1 ·an -1 ) et deux qualités de station (pauvre et riche). Les résultats montrent que les effets de la pollution atmosphérique ne sont pas immé-diats, mais qu'après une à deux rotations, les effets de l'acidification du sol pouvaient réduire de façon significative les ré-serves de carbone (C) de l'écosystème (-25 et -11 % respectivement dans les stations pauvres et riches). Les taux de déposition de N plus élevés que 15 kg N·ha -1 ·an -1 pouvaient atténuer certains des effets négatifs de l'acidification du sol et ont mené à plus de C de l'écosystème (19 et 28 Mg C·ha -1 de plus respectivement dans les stations pauvres et riches qu'avec un faible taux de déposition de N). Cependant, les pertes de N par lessivage pouvaient augmenter de façon importante, ju...

Resilience Assessment of Lowland Plantations Using an Ecosystem Modeling Approach

“…This situation benefits camphor laurels as it reduces N losses from the ecosystem, particularly at the beginning of the rotation when camphor laurels are small and do not capture and use most of the available N. Later, when ash declines and leaf and woody litter decompose, such nutrients are released and can be used by camphor laurel trees. Similar mechanisms to reduce nutrient losses from the ecosystems have been reported before for Chinese sub-tropical forests [28,[31][32][33]. In addition, stand litter production increases in mixed forests, a phenomenon reported before [63].…”

“…Among them, the model FORECAST [20] stands out, as it has been used as a management evaluation tool in many types of forest ecosystems around the world [21][22][23][24][25][26][27], including tropical and sub-tropical forests [28][29][30][31][32][33]. The model is specially designed to examine the impacts of different management strategies at the ecosystem level, accounting for resource competition (intra-and inter-specific) when several species (trees and understory) are present in the same stand, including natural and planted mixedwoods [34,35].…”

Ectomycorrhizal fungi inoculation alleviates simulated acid rain effects on soil ammonia oxidizers and denitrifiers in Masson pine forest

“…As for nitrogen in the soil, nitrate leaching could contribute to the loss of total nitrogen under the simulated acid rain. Previous studies have demonstrated that the high concentrations of base cations or H + in throughfall may result in the loss of soil nitrogen through leaching (Blanco et al, 2012;Xu et al, 2015). Additionally, it was reported that acid rain could inhibit nitrogen mineralization, and thus reduce NH + 4 -N supply (Ouyang et al, 2008).…”

Evaluation of the effects of forest management strategies on carbon sequestration in evergreen broad-leaved (Phoebe bournei) plantation forests using FORECAST ecosystem model

“…The mean annual frost-free period is 270 days, with average annual sunshine time of 1860 h. Soils are predomin antly red earths and yellow-red soils (lateritic clay-domina ted Ferrisoils) with textures ranging from light to medium loam and pH from 4.7 to 5.2. In this warm and humid subtropical monsoon climate with nutrient-poor soils, N is usually the growth-l imiting factor Blanco et al, 2012 ).…”

“…Among them, the model FORECAST (Kimmins et al, 1999 ) stands out. It has been used as a management evaluation tool in many types of forest ecosystems around the world (Sachs and Sollins, 1986;Wang et al, 1995;Morris et al, 1997;Wei et al, 2000Wei et al, , 2003Blanco et al, 2007;Seely et al, 2010 ), including tropical and subtropical forests (Bi et al, 2007;Blanco and González, 2010a,b;Xin et al, 2011;Blanco et al, 2012;Wei et al, 2012 ). The model was specifically designed to examine the impacts of different managemen t strategie s or natural disturbance regimes on long-term site productivity and forest carbon sequestratio n. A detailed description of the FORECAST model can be found in Kimmins et al (1999Kimmins et al ( , 2010 and a brief description of the algorithms simulating C sequestra tion will be presented in the next section.…”