Successful reclamation and revegetation of disturbed sites depends on the availability of sufficient topsoil. Current regulations in western Canada require the replacement of ≥80% of the original topsoil depth (TRD) to restore pre-disturbance productivity. However, salvaged topsoil at many legacy and other disturbed sites is often insufficient to achieve the 80% TRD (TRD80). This 5-year study examined vegetation responses to 50% TRD without organic amendment (TRD50) or amended with either peat (PTRD50) or biochar (BTRD50), relative to the TRD80 treatment, following borrow site reclamation in northeastern Alberta, Canada. Amendments were applied once at rates calculated to bring organic carbon in the topsoil to concentrations approximating those in the TRD80 treatment. Tree and shrub seedling mixes were transplanted following amendment application and vegetation attributes were measured annually thereafter. Results showed that PTRD50 performed as well as TRD80 and outperformed BTRD50 with respect to native species' canopy cover and tree seedling height. Canopy covers of forb and non-native species decreased significantly whereas those of graminoid and native species increased over time for all treatments. Across treatments, native plant species richness increased by 5% per year while non-native species richness decreased by 19% per year. Overall, peat showed a satisfactory rate of recovery and a trajectory toward the natural boreal forest, indicating its potential to improve reclamation success at disturbed boreal sites where salvaged soil is insufficient to attain equivalent land capability. This finding will provide an additional tool for regulators seeking to refine land reclamation guidelines for such sites in boreal forest regions.

中文翻译：

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采用次优表土置换深度和有机改良剂开垦受干扰土地的植被恢复

受干扰地点的成功复垦和重新植被取决于是否有足够的表土。加拿大西部现行法规要求更换 ≥80% 的原始表土深度 (TRD)，以恢复干扰前的生产力。然而，许多遗留和其他受干扰地点的抢救表土通常不足以实现 80% TRD (TRD80)。这项为期 5 年的研究考察了加拿大阿尔伯塔省东北部取土场开垦后，相对于 TRD80 处理，植被对 50% TRD（无有机改良剂 (TRD50) 或用泥炭 (PTRD50) 或生物炭 (BTRD50) 改良）的反应。以计算出的速率应用一次修正，以使表土中的有机碳浓度接近 TRD80 处理中的浓度。施用改良剂后移植乔木和灌木幼苗混合物，此后每年测量植被属性。结果表明，在本地树种的冠层覆盖度和树苗高度方面，PTRD50 的表现与 TRD80 一样，并且优于 BTRD50。对于所有处理，杂草和非本地物种的冠层覆盖显着减少，而禾本科植物和本地物种的冠层覆盖随着时间的推移而增加。在各个处理中，本地植物物种丰富度每年增加 5%，而非本地植物物种丰富度每年下降 19%。总体而言，泥炭显示出令人满意的恢复率和向天然北方森林发展的轨迹，表明其有可能提高受扰动北方地区的开垦成功率，而这些地区的抢救土壤不足以达到同等的土地能力。这一发现将为寻求完善北方森林地区此类地点土地复垦指南的监管机构提供额外的工具。