Soil moisture controls the partitioning of carbon stocks across a managed boreal forest landscape

Abstract

Boreal forests sequester and store vast carbon (C) pools that may be subject to significant feedback effects induced by climatic warming. The boreal landscape consists of a mosaic of forests and peatlands with wide variation in total C stocks, making it important to understand the factors controlling C pool sizes in different ecosystems. We therefore quantified the total C stocks in the organic layer, mineral soil, and tree biomass in 430 plots across a 68 km2 boreal catchment. The organic layer held the largest C pool, accounting for 39% of the total C storage; tree and mineral C pools accounted for 38% and 23%, respectively. The size of the soil C pool was positively related to modelled soil moisture conditions, especially in the organic soil layer (R2 = 0.50). Conversely, the tree C pool exhibited a unimodal relationship: storage was highest under intermediate wetness conditions. The magnitude and variation in the total soil C stocks observed in this work were comparable to those found at the national level in Sweden, suggesting that C accumulation in boreal landscapes is more sensitive to local variation resulting primarily from differences in soil moisture conditions than to regional differences in climate, nitrogen deposition, and parent material.

Multi-scale soil moisture data and process-based modeling reveal the importance of lateral groundwater flow in a subarctic catchment

“…. It is also a key variable controlling soil microbial activity and consequent greenhouse gas emissions (Bonan, 1990;Karhu et al, 2014;Lohila et al, 2016;Makhnykina et al, 2020), and soil carbon balance (Larson et al, 2023). In the boreal and subarctic region, the climate change is predicted to amplify seasonal variability of soil moisture due to longer and more frequent summer droughts, increased autumn and winter precipitation (Holmberg et al, 2014;Ruosteenoja et al, 2018), and changes in snow accumulation and melt (Räisänen, 2021).…”

Unraveling boreal forest composition and drivers across scales in eastern Siberia

“…Topographical variables, which can be used as proxies for hydrological processes and incoming radiation at the local scale, are a key control of plant community distribution [16][17][18][19][20] and possibly of the abundance of Siberian larch (Larix) [21]. Furthermore, topographic factors significantly affect soil moisture and nutrient availability impacting the productivity and carbon storage of boreal forests [22], and influence the recovery and succession of boreal forests following disturbances like wildfires [23]. A gap exists in understanding how various factors such as climate and topography influence forest-type distribution across spatial scales, ranging from local (meters) to regional (kilometers) scale.…”

“…International programs provide global landcover maps [41,42] of multiple forest types at a spatial resolution ranging from 100 to 300 m [41,43]. Despite these advances, many applications in forest ecology demand finer detail than the currently available maps offer, particularly when attempting to elucidate the intricate drivers of forest types in boreal ecosystems, or estimating forest growing stock volumes [22,[44][45][46]. Currently, there is no high-resolution map focusing on mixed evergreen-summergreen boreal forests in eastern Siberia [47] which would highlight the overlapping niches between forest types.…”