Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Dr., Peterborough, ON K9J 7B8, Canada.
Trent School of the Environment, Trent University, 1600 West Bank Dr., Peterborough, ON K9J 7B8, Canada.
Sci Total Environ. 2023 Dec 15;904:166734. doi: 10.1016/j.scitotenv.2023.166734. Epub 2023 Sep 4.
Increasing forest cover by regreening mining and smelting degraded landscapes provides an opportunity for global carbon (C) sequestration, however, the reported effects of regreening on soil C processes are mixed. One of the world's largest regreening programs is in the City of Greater Sudbury, Canada and has been ongoing since 1978. Prior to regreening, soils in the City of Greater Sudbury area were highly eroded, acidic, rich in metals, and poor in nutrients. This study used a chronosequence approach to investigate how forest soil C pools and fluxes have changed with stand age in highly "eroded" sites with minimal soil cover (n = 6) and "stable" sites covered by soil (n = 6). Encouragingly, the relationship between stand age and soil C processes (litterfall, litter decomposition, soil respiration, fine root growth) at both stable and eroded sites were comparable to observations reported for jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Ait.) plantations that have not been subject to over a century of industrial impacts. There was a strong "home-field advantage" for local decomposers, where litter decomposition rates were higher using a site-specific pine litter compared with a common pine litter. Higher soil respiration at eroded sites was linked to higher soil temperature, likely because of a more open tree canopy. Forest floor C pools increased with stand age while mineral soil C and aggregate C concentrations decreased with stand age. This loss of soil C is small relative to the substantial increases in aboveground tree and forest floor C pools, leading to a sizeable increase in total ecosystem C pools following regreening.
通过重新造林来增加森林覆盖率，从而为全球碳 (C) 封存提供了机会，然而，重新造林对土壤 C 过程的影响却存在差异。世界上最大的重新造林计划之一是在加拿大萨德伯里市进行的，该计划自 1978 年以来一直在进行。在重新造林之前，萨德伯里市地区的土壤受到严重侵蚀、呈酸性、富含金属且养分贫缺。本研究采用时间序列方法，研究了在高度“侵蚀”的无土壤覆盖（n = 6）和土壤覆盖稳定（n = 6）的地点，森林土壤 C 库和通量如何随林龄变化。令人鼓舞的是，稳定和侵蚀地点的林龄与土壤 C 过程（凋落物、凋落物分解、土壤呼吸、细根生长）之间的关系与未受到一个多世纪工业影响的黑云杉（Pinus banksiana Lamb.）和湿地松（Pinus resinosa Ait.）人工林的观测结果相似。当地分解者具有很强的“主场优势”，使用特定地点的松树凋落物比使用普通松树凋落物时，凋落物分解率更高。侵蚀地点的土壤呼吸率较高与土壤温度较高有关，可能是由于树冠更开阔。林下地被层 C 库随林龄增加而增加，而矿质土壤 C 和团聚体 C 浓度随林龄增加而降低。与地上树木和林下地被层 C 库的大量增加相比，土壤 C 的损失相对较小，这导致了重新造林后总生态系统 C 库的大量增加。
