Southern boundary areas of high-latitude permafrost regions may represent the future permafrost temperature regimes; therefore, understanding the carbon stocks and their stability in these systems can shed light on the permafrost carbon cycle under a warming climate. In this study, we sampled soils at three sites representing three differing land covers (forest swamp, dry forest, and shrub swamp) located in the southern boundary area of a high-latitude permafrost region and investigated their carbon fractions and the relationships of these fractions with soil physicochemical parameters in the active and permafrost layers. The results show that the proportion of active carbon is higher in permafrost than in the active layer under forest swamp and dry forest, implying that carbon pools in the permafrost are more decomposable. However, in shrub swamp, the active carbon components in the permafrost layer are lower than in the active layer. Soil pH and water content are the most significant factors associated with soil organic carbon concentration both in the active layers and in the permafrost layers. Our results suggest that, although soil organic carbon concentrations largely decrease with depth, the proportion of the forest swamp, dry forest labile carbon is higher in the permafrost layer than in the active layer and that the vertical distribution of labile carbon proportions is related to land covers.

The majority of European forests are managed and influenced by natural disturbances, with wind being the dominant agent, both of which affect the ecosystem's carbon budget. Therefore, investigating the combined effect of wind damage and different soil preparation practices on forest carbon pools is of great importance. This study examines changes in carbon stocks in the soil and biomass of two 5-year-old Scots pine stands (namely Tlen1 and Tlen2), which were established approximately 2 years after a large-scale wind disturbance in northwestern Poland. These neighboring sites differ in terms of the reforestation methods applied, particularly regarding soil preparation: ploughing disc trenching at Tlen1 and partial preparation through local manual scalping at Tlen2. Using nearby forest soils as the best available reference for the pre-windthrow state, it was estimated that the total carbon stock in the soil (up to 50 cm depth, both organic and mineral) was depleted by approximately 17 % at Tlen1 and 7 % at Tlen2. The between-site differences were around 18 %, which nearly doubled when considering only the top 20 cm of the soil profile. In contrast, the total biomass, as well as the carbon stock in biomass, were significantly higher at the site with soil prepared using moderate ploughing (Tlen1) compared to the area with partial soil preparation (Tlen2). Our findings indicate that ploughing disc trenching, aimed mainly at weed removal and improving soil properties, significantly enhanced Scots pine seedlings' growth, survival, and development during the first four years after planting. Finally, when both carbon stock estimates are pooled together, regardless of the chosen technique, the growing biomass in the investigated stands did not fully compensate for the carbon losses caused by mechanical soil preparation. However, in the short term, the overall change in the ecosystem's carbon balance was only slightly negative and comparable between the two sites.

Maritime Antarctica has a milder climate than the Antarctic continent and is naturally more sensitive to rising global temperature. Therefore, it is necessary to understand the soils, including those with permafrost, as well as the relief and the occurrence of organic carbon at Byers Peninsula. This study aims therefore to investigate soil physical and chemical properties at Byers Peninsula, Maritime Antarctica, in particular, the distribution of organic carbon. Thirteen soil profiles were described, collected, and subjected to a physical, chemical, and spatial analysis. Colonization by avifauna and vegetation is important for inputing soil organic carbon at Byers Peninsula. Cryoturbation and permafrost are crucialforthe redistribution of the C pool. Distribution of organic carbon on the Byers Peninsula have shown that its concentrations are higher and more punctual at the surface, but also that carbon has been redistributed to deeper layers. Gelisols (Cryosols) are important C pools. They are extremely useful from the environmental monitoring perspective as they represent areas sensitive to temperature increases on the Antarctic Peninsula caused by global climate changes. Using geomorphological groups is one way to improve the understanding of these relief forms, soil and rocktypes, vegetation patterns, and the presence of permafrost.

Reduction in snow cover is a prominent aspect of global change. Freeze-thaw cycles (FTCs) of different amplitudes and durations in soil due to insufficient thermal insulation may alter microbial diversity and key ecological functions mediated by microorganisms. These changes could then further alter the cycling of material and energy in the ecosystem. Yet despite many assessments, the impact of FTCs upon microbial diversity remains poorly understood. Here, 546 observations from 61 published studies were collected for a global meta-analysis with the objective to explore how soil microbial diversity and C and N dynamics it drives respond to FTCs. The results showed that: in general, FTCs did not lead to a reduction of microbial alpha-diversity, but they did reduce levels of soil microbial biomass carbon, microbial biomass nitrogen, and phospholipid fatty acid by 7%, 12%, and 11%, respectively; they also significantly changed the microbial community structure. FTCs did not significantly affect the alpha-diversity of bacteria and fungi, but community structures of both were changed significantly, with that of the bacteria more sensitive to FTCs. FTCs were responsible for a 6% decrease in functions related to C, N cycling, which could be explained by the changes found in microbial biomass and community structure. FTCs could also indirectly impact microbial biomass via changed pH and soil water content (SWC). The response of microbial community to FTCs was related to the FTC frequency, freezing temperature and sampling time. FTCs had a large effect on the C and N pool components and fluxes in soil. It is particularly noteworthy that FTCs drove a 137% increase in N2O emission. Further, the changes in pH and SWC directly affected the C and N pool components and fluxes. The results of current meta-analysis deepen the comprehensive understanding of the effects of FTCs on the soil microbial community and C and N dynamics it mediated, and provide a reference for subsequent research in terms of experimental scheme and scientific issues requiring close attention.

Studies on the responses of soil organic carbon (SOC) and nitrogen dynamics to Holocene climate and environment in permafrost peatlands and/or wetlands might serve as analogues for future scenarios, and they can help predict the fate of the frozen SOC and nitrogen under a warming climate. To date, little is known about these issues on the Qinghai -Tibet Plateau (QTP). Here, we investigated the accumulations of SOC and nitrogen in a permafrost wetland on the northeastern QTP, and analyzed their links with Holocene climatic and environmental changes. In order to do so, we studied grain size, soil organic matter, SOC, and nitrogen contents, bulk density, geochemical parameters, and the accelerator mass spectrometry (AMS) 14C dating of the 216-cm-deep wetland profile. SOC and nitrogen contents revealed a general uptrend over last 7300 years. SOC stocks for depths of 0-100 and 0-200 cm were 50.1 and 79.0 kgC m-2, respectively, and nitrogen stocks for the same depths were 4.3 and 6.6 kgN m-2, respectively. Overall, a cooling and drying trend for regional climate over last 7300 years was inferred from the declining chemical weathering and humidity index. Meanwhile, SOC and nitrogen accumulated rapidly in 1110-720 BP, while apparent accumulation rates of SOC and nitrogen were much lower during the other periods of the last 7300 years. Consequently, we proposed a probable conceptual framework for the concordant development of syngenetic permafrost and SOC and nitrogen accumulations in alpine permafrost wetlands. This indicates that, apart from controls of climate, non-climate environmental factors, such as dust deposition and site hydrology, matter to SOC and nitrogen accumulations in permafrost wetlands. We emphasized that environmental changes driven by climate change have important impacts on SOC and nitrogen accumulations in alpine permafrost wetlands. This study could provide data support for regional and global estimates of SOC and nitrogen pools and for global models on carbon -climate interactions that take into account of alpine permafrost wetlands on the northeastern QTP at mid-latitudes.

We investigated total storage and landscape partitioning of soil organic carbon (SOC) in continuous permafrost terrain, central Canadian Arctic. The study is based on soil chemical analyses of pedons sampled to 1-m depth at 35 individual sites along three transects. Radiocarbon dating of cryoturbated soil pockets, basal peat and fossil wood shows that cryoturbation processes have been occurring since the Middle Holocene and that peat deposits started to accumulate in a forest-tundra environment where spruce was present (similar to 6000 cal yrs BP). Detailed partitioning of SOC into surface organic horizons, cryoturbated soil pockets and non-cryoturbated mineral soil horizons is calculated (with storage in active layer and permafrost calculated separately) and explored using principal component analysis. The detailed partitioning and mean storage of SOC in the landscape are estimated from transect vegetation inventories and a land cover classification based on a Landsat satellite image. Mean SOC storage in the 0-100-cm depth interval is 33.8 kg C m(-2), of which 11.8 kg C m(-2) is in permafrost. Fifty-six per cent of the total SOC mass is stored in peatlands (mainly bogs), but cryoturbated soil pockets in Turbic Cryosols also contribute significantly (17%). Elemental C/N ratios indicate that this cryoturbated soil organic matter (SOM) decomposes more slowly than SOM in surface O-horizons. Copyright (C) 2010 John Wiley & Sons, Ltd.