Woods Hole Research Center, 149 Woods Hole Road, Falmouth, Massachusetts, 02540-1644, USA.
Zambia Forestry Department, Ministry of Lands, Natural Resources and Environmental Protection, P.O. Box 50042, Lusaka, Zambia.
Ecol Appl. 2017 Jul;27(5):1578-1593. doi: 10.1002/eap.1550. Epub 2017 Jun 12.
Understanding the anthropogenic and natural controls that affect the patterns, distribution, and dynamics of terrestrial carbon is crucial to meeting climate change mitigation objectives. We assessed the human and natural controls over aboveground tree biomass density in African dry tropical forests, using Zambia's first nationwide forest inventory. We identified predictors that best explain the variation in biomass density, contrasted anthropogenic and natural sites at different spatial scales, and compared sites with different stand structure characteristics and species composition. In addition, we evaluated the effects of different management and conservation practices on biomass density. Variation in biomass density was mostly determined by biotic processes, linked with both species richness and dominance (evenness), and to a lesser extent, by land use, environmental controls, and spatial structure. Biomass density was negatively associated with tree species evenness and positively associated with species richness for both natural and human-modified sites. Human influence variables (including distance to roads, distance to town, fire occurrence, and the population on site) did not explain substantial variation in biomass density in comparison to biodiversity variables. The relationship of human activities to biomass density in managed sites appears to be mediated by effects on species diversity and stand structure characteristics, with lower values in human-modified sites for all metrics tested. Small contrasts in carbon density between human-modified and natural forest sites signal the potential to maintain carbon in the landscape inside but also outside forestlands in this region. Biodiversity is positively related to biomass density in both human and natural sites, demonstrating potential synergies between biodiversity conservation and climate change mitigation. This is the first evidence of positive outcomes of protected areas and participatory forest management on carbon storage at national scale in Zambia. This research shows that understanding controls over biomass density can provide policy relevant inputs for carbon management and on ecological processes affecting carbon storage.
了解影响陆地碳格局、分布和动态的人为和自然控制因素对于实现气候变化减缓目标至关重要。我们利用赞比亚的首次全国性森林清查，评估了人为和自然因素对非洲干热带森林地上树木生物量密度的控制作用。我们确定了最佳解释生物量密度变化的预测因子，对比了不同空间尺度上的人为和自然地点，并比较了具有不同林分结构特征和物种组成的地点。此外，我们评估了不同管理和保护实践对生物量密度的影响。生物量密度的变化主要由生物过程决定，与物种丰富度和优势度（均匀度）有关，在较小程度上还与土地利用、环境控制和空间结构有关。生物量密度与自然和人为干扰地点的物种均匀度呈负相关，与物种丰富度呈正相关。与生物多样性变量相比，人为影响变量（包括道路距离、城镇距离、火灾发生和站点人口）对生物量密度的变化没有解释力。在管理地点，人类活动与生物量密度的关系似乎是通过对物种多样性和林分结构特征的影响来介导的，所有测试的指标在人为干扰地点的值都较低。人为干扰和自然森林地点之间碳密度的微小差异表明，在该地区的林地内部和外部都有潜力保持碳储量。生物多样性与人为和自然地点的生物量密度呈正相关，这表明在生物多样性保护和气候变化减缓方面存在潜在的协同作用。这是赞比亚首次在国家范围内证明保护区和参与式森林管理对碳储存的积极影响。这项研究表明，了解生物量密度的控制因素可以为碳管理和影响碳储存的生态过程提供具有政策相关性的投入。
