Data from: Disturbance intensity is a stronger driver of biomass recovery than remaining tree-community attributes in a managed Amazonian forest

1.Forest recovery following management interventions is important to maintain ecosystem functioning and the provision of ecosystem services. It remains, however, largely unclear how aboveground biomass (AGB) recovery of species-rich tropical forests is affected by disturbance intensity and post-disturbance (remaining) tree-community attributes, following logging and thinning interventions.

2.We investigated whether annual AGB increment (∆AGB) decreases with management-related disturbance intensity (disturbance hypothesis), and increases with the diversity (niche-complementarity hypothesis) and the community-weighted mean (CWM) of acquisitive traits of dominant species (biomass-ratio hypothesis) in the remaining tree community.

3.We analysed data from a long-term forest-management experiment in the Brazilian Amazon over two recovery periods: post-logging (1983-1989) and post-thinning (1995-2012). We computed the ∆AGB of surviving trees, recruit trees and of the total tree community. Disturbance intensity was quantified as basal area reduction and basal area remaining. Remaining diversity (taxonomic, functional and structural) and CWM of five functional traits linked to biomass productivity (specific leaf area, leaf nitrogen and phosphorous concentration, leaf toughness and wood density) were calculated for the post-intervention inventories. Predictors were related to response variables using multiple linear regressions and structural equation modelling.

4.We found support for the disturbance hypothesis in both recovery periods. AGB increment of survivors and of the total tree community increased with basal area remaining, indicating the importance of remaining growing stock for biomass recovery. Conversely, AGB increment of recruit trees increased with basal area reduction because changes in forest structure increased resource availability for young trees. We did not find consistent support for the niche-complementarity and biomass-ratio hypotheses, possibly because of a high redundancy in these extremely species-rich forests.

5.Synthesis and applications. The intensity of disturbance through management, expressed as basal area reduction and basal area remaining, was consistently more important for explaining forest biomass recovery following harvesting and thinning than remaining diversity or trait composition. This points to the importance of controlling logging and thinning intensity in forests of the eastern Amazon. Low to moderate harvesting intensities permitted by the current legislation for the Brazilian Amazon (30 m³ ha−1) will likely not impair biomass recovery in these forests.

1. 经人为经营干预后的森林恢复，对维持生态系统功能与生态系统服务供给至关重要。然而，在采伐与疏伐干预后，物种丰富的热带森林的地上生物量（aboveground biomass, AGB）恢复受干扰强度及干扰后留存林木群落特征的影响机制，目前仍在很大程度上不明晰。
2. 本研究旨在探究：在留存林木群落中，年地上生物量增量（annual AGB increment, ∆AGB）是否随经营相关干扰强度升高而降低（即干扰假说），并随物种多样性（即生态位互补假说）及优势种获取型功能性状的群落加权平均（community-weighted mean, CWM）升高而增加（即生物量比假说）。
3. 本研究分析了巴西亚马逊（Brazilian Amazon）地区一项长期森林经营试验在两个恢复周期内的数据：采伐后恢复期（1983-1989年）与疏伐后恢复期（1995-2012年）。研究计算了存活林木、新招募林木及全部林木群落的年地上生物量增量（∆AGB）。干扰强度以胸高断面积减少量与留存胸高断面积进行量化。针对干预后的森林调查数据，研究人员计算了留存群落的多样性（分类、功能及结构多样性）以及与生物量生产力相关的5种功能性状的群落加权平均（CWM），这5种性状分别为比叶面积、叶片氮磷浓度、叶片韧性与木材密度。本研究采用多元线性回归与结构方程模型，将预测变量与响应变量进行关联分析。
4. 本研究在两个恢复周期中均得到了支持干扰假说的证据。存活林木及全部林木群落的年地上生物量增量随留存胸高断面积升高而增加，这表明留存立木蓄积量对生物量恢复具有重要意义。与之相反，新招募林木的年地上生物量增量随胸高断面积减少量升高而增加，这是因为森林结构变化提升了幼树可获取的资源量。本研究未得到支持生态位互补假说与生物量比假说的一致性证据，这可能是由于这些极度物种丰富的森林中存在较高的功能冗余。
5. 综合与应用。经经营产生的干扰强度（以胸高断面积减少量与留存胸高断面积表征），在解释采伐与疏伐后森林生物量恢复方面，始终比留存群落多样性或性状组成更为关键。这表明在东部亚马逊地区的森林中，控制采伐与疏伐强度具有重要意义。巴西亚马逊现行立法允许的低至中等采伐强度（30 m³ ha−1），大概率不会损害此类森林的生物量恢复能力。