Environmental Studies Program, Department of Geography, Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA; Departamento de Engenharia Florestal, Universidade de Brasília, Brasília, DF, Brazil.
Environmental Studies Program, Department of Geography, Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA.
Sci Total Environ. 2020 Apr 20;714:136780. doi: 10.1016/j.scitotenv.2020.136780. Epub 2020 Jan 20.
One-fourth of Brazilian Amazonia is managed for timber production, but only a small portion of active logging sites follow sustainable forest management plans (SFMPs). Amazon forests without SFMPs are susceptible to deforestation because such plans integrate the use of forest products and conservation goals by allowing selective wood extraction following regulations aimed at reducing the long-term impact of logging. However, it remains uncertain whether reduced-impact selective logging typical of SFMPs (17-20 m ha yr of 38-70 species) changes forest regeneration, carbon (C) stocks, and nutrient cycling. Here, we tested the hypothesis that litter and soil biogeochemical parameters serve as indicators of sustainable logging as forest regeneration, C stocks, and C-to-nutrient ratios in soil and litter become progressively similar to those of primary forests as time elapses after logging. We used a chronosequence spanning nine years since logging to relate litter and soil (at 0-10, 10-30, 30-50 cm depth) C stocks and 12 and 15 biogeochemical parameters, respectively, as well as canopy cover and tree seedling density (10-150 cm tall) in upland evergreen Amazon forests. In one unlogged and four logged stands sampled three, five, seven, and nine years after logging, we compared 15 permanent plots (three replicated 0.5 ha plots per time-since-logging category). We found that five parameters explained >80% of the variation in soil and litter properties among logged and unlogged stands. Litter parameters were more sensitive to logging than soil parameters, as litter C stocks and C-to-nutrient ratios increased systematically after logging. Canopy cover decreased over time and was ~14% lower nine years after logging. Total seedling density did not change consistently over time but was ~54% higher seven years after logging. Our data suggest that the SFMP guidelines have served the purpose of maintaining soil quality and forest regeneration. Litter and soil parameters can be useful indicators of sustainable forest management in upland evergreen forests in Central Amazonia.
巴西亚马孙地区的四分之一用于木材生产，但只有一小部分活跃的伐木区遵循可持续森林管理计划 (SFMP)。没有 SFMP 的亚马孙森林容易受到森林砍伐的影响，因为这些计划通过允许在遵守旨在减少伐木长期影响的规定下选择性地采伐木材，将森林产品的使用和保护目标结合起来。然而，目前尚不确定 SFMP 中典型的低影响选择性伐木（17-20 m ha yr 的 38-70 个物种）是否会改变森林再生、碳 (C) 储量和养分循环。在这里，我们检验了这样一个假设，即凋落物和土壤生物地球化学参数可用作可持续伐木的指标，因为随着时间的推移，森林再生、土壤和凋落物中的 C 储量以及 C 与养分的比率逐渐与原始森林相似。我们使用了一个从伐木开始到现在已经九年的时间序列，将凋落物和土壤（0-10、10-30、30-50 cm 深度）的 C 储量以及 12 和 15 个生物地球化学参数分别与林冠覆盖和树木幼苗密度（10-150 cm 高）相关联。在一个未砍伐和四个砍伐的林分中，在砍伐后 3、5、7 和 9 年分别进行了采样，我们比较了 15 个永久性样地（每个时间尺度重复 3 个 0.5 ha 的样地）。我们发现，五个参数解释了 >80%的采伐和未采伐林分之间土壤和凋落物特性的差异。与土壤参数相比，凋落物参数对伐木更为敏感，因为伐木后凋落物 C 储量和 C 与养分的比率系统增加。林冠覆盖随着时间的推移而减少，在伐木后 9 年减少了约 14%。总的幼苗密度随着时间的推移没有一致的变化，但在伐木后 7 年增加了约 54%。我们的数据表明，SFMP 指南的目的是维持土壤质量和森林再生。凋落物和土壤参数可以成为亚马孙中部旱地常绿林可持续森林管理的有用指标。
