Rising air temperatures, intensifying wildfire activity, and human disturbance are driving rapid permafrost thaw across the subarctic, particularly for thaw-sensitive discontinuous permafrost. The Taiga Plains and Taiga Shield ecozones of northwestern Canada have experienced rapid and widespread permafrost thaw over recent decades, creating significant community concerns and knowledge gaps. In direct response, this review: (1) outlines the observed thaw-induced changes in landcover, hydrology, and water quality; (2) discusses the underlying drivers and mechanisms of these changes; and (3) identifies knowledge gaps to guide future research in the discontinuous permafrost zone of the Taiga Plains and Shield (study region). In the Taiga Plains, permafrost is mainly associated with peatlands where its thaw increases the extent of thermokarst wetlands at the expense of treed peatlands underlain by permafrost. This thaw-induced landcover change enhances the hydrologic connectivity of the landscape, which increases basin-scale runoff and annual streamflow, and enables wetland drainage such that permafrost-free treed wetlands develop. Thaw-induced landcover changes in the lake- and bedrock-dominated Taiga Shield are not well known but are expected to occur as limited or minor thermokarst pond development and changing lake extent due to the low (<5%) peatland coverage of this ecozone. Permafrost thaw also increases the connectivity between surface water and groundwater, leading to increasing winter baseflows and possibly icing (aufeis) development. Such increases in hydrologic connectivity can enhance the mobilization of parameters of concern for water quality, both in the Taiga Plains and Shield. The thawing of peatlands will likely increase the transport and concentrations of dissolved organic carbon and metals bound to organic compounds, including methylmercury. Further work is needed to fully understand the biogeochemical processes operating in these systems and the degree to which thawing peatlands will impact water quality and quantity at the larger basin scale. The greatest knowledge gaps across the study region surround the evolution of thaw-activated groundwater flow systems and the consequences for wetland biogeochemistry, the rates and patterns of permafrost thaw, contaminant transport, and streamflow of larger river systems. This synthesis not only informs future research directions in the study region but extends to similar subarctic peatland and Shield environments common throughout the circumpolar north.

气温上升、野火活动加剧和人为干扰正在推动整个亚北极地区的永久冻土快速融化，特别是对于解冻敏感的不连续永久冻土。针叶林平原和针叶林地盾生态区近几十年来，加拿大西北部经历了快速和广泛的永久冻土融化，造成了严重的社区问题和知识差距。作为直接回应，本综述： (1) 概述了观察到的解冻引起的土地覆盖、水文和水质变化；(2) 讨论这些变化的潜在驱动因素和机制；(3) 确定知识差距以指导未来在针叶林平原和地盾（研究区域）的不连续永久冻土带的研究。在针叶林平原，永久冻土主要与泥炭地有关，其解冻增加了热岩溶湿地的范围，但以永久冻土下的树木泥炭地为代价。这种解冻引起的土地覆盖变化增强了景观的水文连通性，从而增加了流域规模的径流和年径流量，并实现湿地排水，从而发展无多年冻土的树木湿地。在以湖泊和基岩为主的针叶林地盾中，解冻引起的土地覆盖变化并不为人所知，但由于该生态区的泥炭地覆盖率低（<5%），预计会随着热岩溶池塘的有限或轻微的发展以及湖泊范围的变化而发生。永久冻土融化还增加了地表水和地下水之间的连通性，导致冬季基流增加，并可能导致结冰（aufeis）的发展。这种水文连通性的提高可以加强对泰加平原和地盾水质参数的调动。泥炭地的融化可能会增加溶解的有机碳和与有机化合物（包括甲基汞）结合的金属的迁移和浓度. 需要进一步的工作来充分了解在这些系统中运行的生物地球化学过程以及解冻泥炭地将在多大程度上影响更大流域范围内的水质和水量。整个研究区域最大的知识差距围绕着解冻激活的地下水流动系统的演变以及对湿地生物地球化学的影响、永久冻土融化的速率和模式、污染物迁移和较大河流系统的流量。这种综合不仅为研究区域的未来研究方向提供了信息，而且还扩展到了整个极地北部常见的类似亚北极泥炭地和地盾环境。