The hydrological implications of discontinuous permafrost thaw in peatland-dominated basins are not well understood. While there is evidence suggesting that permafrost-thaw-driven land cover change increases annual runoff and the runoff ratio in the Taiga Plains of northwestern Canada, few studies have evaluated the impact on small to medium sized basins (<105 km2) outside this ecoregion. Here, we assess runoff, runoff ratio, and precipitation trends for 34 peatland-dominated basins, of which 28 are in the discontinuous and sporadic permafrost zones and 6 in adjacent permafrost-free environments. We calculated annual and monthly trends between 1970 and 2016 using the Mann-Kendall test and found that annual runoff, runoff ratio, and precipitation increased significantly in 25%, 16%, and 13% of basins respectively, at a 5% significance level, and decreased significantly in 3%, 19%, and 9% of basins, respectively. Increased annual runoff ratios occurred exclusively in basins overlying permafrost, while increases and decreases in annual runoff and precipitation were found in both permafrost and permafrost-free basins. Increases of annual runoff and runoff ratio occurred independently of precipitation changes in only the Taiga Plains and in the Western Siberian Plain. Runoff during winter increased significantly in all ecoregions and occurred independently of the areal extent of permafrost, although the magnitude of these increases was small compared with those of April and May.

&lt;p&gt;Thawing discontinuous permafrost in subarctic peatland-dominated landscapes is increasingly recognized as an indicator of a warming climate and potentially shifting these landscapes from atmospheric carbon store to source. Furthermore, in certain discontinuous permafrost landscapes (e.g., northwest Canada) the thaw of permafrost peatlands leads to a reorganization of near-surface flow paths as permafrost-free peatlands expand, connect, merge, and drain. Collectively, these permafrost-thaw-driven landcover and hydrological changes have increased runoff and altered biogeochemical cycles threatening natural resources and critical infrastructure in Indigenous peoples&amp;#8217; traditional territories along with aquatic and terrestrial wildlife habitat. Owing to the region&amp;#8217;s remote position and vast scale, comparatively less is known about the landcover and hydrological impacts of permafrost thaw in the Hudson Plains, the world&amp;#8217;s third largest peatland region (370,000 km&lt;sup&gt;2&lt;/sup&gt;) and southern most extent continental permafrost. For this study, we assign specific hydrological functions to individual peatland types based on their form, to then infer hydrological flux and storage processes within and between peatlands un a circuitry analog, at the scale of the peatland complexes and peatland complex regions. We analyze several remotely sensed data, including high-resolution lidar, historical air photographs, and recent panchromatic and multispectral satellite imagery along a latitudinal transect to evaluate peatland form, complex, and regional patterns. We then summarise these results and interpretation to present an initial vulnerability map of peatland complexes in the Hudson Plains to permafrost-thaw-driven hydrological change. &amp;#160;&lt;/p&gt;

The Hudson Plains, Canada, is one of the largest, undisturbed peatland regions (370,000 km2) in the world. Air temperature in the Hudson Plains is increasing rapidly leading to unprecedented permafrost thaw. The region's remoteness has hindered our knowledge of how permafrost thaw alters peatland land cover and hydrological response at multiple scales. To assess which landscapes in the Hudson Plains are vulnerable to such disturbances, we analysed latitudinal distributions of land cover over a 300‐km transect spanning the sporadic (<30% areal) to continuous (>80% areal) permafrost zone in northern Ontario and quantified land cover changes over 40 years using multiple remote sensing datasets (lidar, air photographs, and high‐resolution satellite imagery). We then evaluated these landscapes at a fundamental hydrological unit, the peatland complex, identified five peatland complex types, and conceptualized their potential hydrological response using circuitry analogues. Over four decades, we found that permafrost peatlands declined by 4%, 8.5%, and 2% areal in the sporadic, discontinuous, and continuous permafrost zones, respectively. Circuitry analogues partitioned peatland complexes into their component peatland forms (e.g., permafrost peatland, bog, and fen) and represented each component's hydrological function using an electrical equivalent (e.g., generator, switch, and conductor). When interpreted at the landscape scale, circuitry analogues demonstrated latitudinal patterns in landscape structure (i.e., circuitry wiring) and indicated where permafrost thaw will have the greatest impact on landscape structure (i.e., rewiring) and therefore hydrological response. Based on these analyses, we suggest a 60‐km latitudinal segment (54.5°N to 54.9°N) where peatland complexes are most vulnerable to permafrost‐thaw‐induced land cover and hydrological change and should therefore be the focus of future research and monitoring efforts.