Department of Forest Sciences, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Av. Pádua Dias, 11, CP 9, Piracicaba, SP 13418-900, Brazil; Department of Forest & Conservation Sciences, University of British Columbia, 3041-2424 Main Mall, Vancouver, BC V6T1Z4, Canada; Embrapa Amazônia Oriental, Brazilian Agricultural Research Corporation, Trav. Doutor Enéas Pinheiro, s/n, CP 48, Belém, PA 66095-100, Brazil.
Embrapa Amazônia Oriental, Brazilian Agricultural Research Corporation, Trav. Doutor Enéas Pinheiro, s/n, CP 48, Belém, PA 66095-100, Brazil.
Sci Total Environ. 2022 Jul 1;828:154425. doi: 10.1016/j.scitotenv.2022.154425. Epub 2022 Mar 8.
Forest regeneration has increased in many tropical abandoned lands and current restoration commitments in this region aim to restore over 1,400,000 km of degraded land by 2030. Although regenerating forests recover biomass, biodiversity, and processes with time, the recovery trajectories may be uncertain due to past disturbances. Currently, there is a lack of knowledge to sustain the effectiveness of passive regeneration for the recovery of riparian forests and the adjacent waterbodies in the tropics, which may compromise the outcomes of ongoing and future tropical riparian restoration programs. We evaluated the drivers of riparian forest structural recovery and how this relates to stream conditions in 12 abandoned pasturelands in eastern Brazilian Amazonia. These pasturelands range across regeneration age (pasture (PA) - 0 to 4 years; young regeneration (YR) - 8 to 12 years; old regeneration (OR) - 18 to 22 years) and years of past land-use (PA - 23.25 average years of past land-use, YR - 18.25, OR - 7). We compared the conditions of these sites to 4 reference sites with conserved forests (REF, >100 years), where there was no recorded pasture use in the past. Short-term responses of forests and streams to passive regeneration indicated high ecosystem resilience after low to intermediate past land-use intensity, reflected in the improvement of stream ecosystems. Such high resilience is possibly attributable to low- to intermediate-intensity pasture-related disturbances, remaining forest matrix, and residual structures (e.g. roots, sprouts, and in-stream wood) observed in the area. Our results suggest a recovery by 12 to 20 years for riparian forests of this region. However, areas degraded by intensive land-use apparently showed delayed recovery. We conclude that seizing resilience windows (defined here as the period when ecosystems retain high potential resilience) is essential to foster passive recovery of riparian forests and streams more cost-effectively in the tropics.
森林在许多热带废弃土地上得到了再生，目前该地区的恢复承诺旨在到 2030 年恢复超过 140 万平方千米退化土地。虽然再生森林会随着时间的推移恢复生物量、生物多样性和生态系统过程，但由于过去的干扰，恢复轨迹可能是不确定的。目前，对于热带河流边缘森林和相邻水体的被动再生恢复，缺乏维持其有效性的知识，这可能会影响正在进行和未来热带河流边缘恢复计划的结果。我们评估了河流边缘森林结构恢复的驱动因素，以及这些因素与热带东亚马孙河流域 12 个废弃牧场溪流状况之间的关系。这些牧场跨越再生年龄（牧场（PA）-0 至 4 年；幼龄再生（YR）-8 至 12 年；老龄再生（OR）-18 至 22 年）和过去土地利用年限（PA-23.25 年平均过去土地利用年限，YR-18.25 年，OR-7 年）。我们将这些地点的情况与 4 个具有保护森林（REF，>100 年）的参考地点进行了比较，这些参考地点过去没有记录到牧场使用情况。森林和溪流对被动再生的短期响应表明，在过去土地利用强度低至中等的情况下，生态系统具有高度的恢复力，这反映在溪流生态系统的改善上。这种高恢复力可能归因于低至中等强度的与牧场相关的干扰、剩余的森林基质和残留结构（例如，根、芽和溪流中的木材）在该地区的存在。我们的研究结果表明，该地区的河流边缘森林可能在 12 至 20 年内恢复。然而，明显由高强度土地利用退化的地区恢复速度较慢。我们的结论是，抓住恢复弹性窗口（在此定义为生态系统保持高潜在恢复力的时期）对于更具成本效益地促进热带河流边缘森林和溪流的被动恢复至关重要。
