Permafrost degradation at two monitored palsa mires in north-west Finland

Palsas and peat plateaus are expected to disappear from many regions, including Finnish Lapland. However, detailed long-term monitoring data of the degradation process on palsas are scarce. Here, we present the results of the aerial photography time series analysis (1959–2021), annual real-time kinematic (RTK) GNSS and active layer monitoring (2007–2021), and annual unoccupied aerial system surveys (2016–2021) at two palsa sites (Peera and Laassaniemi, 68∘ N) located in north-west Finland. We analysed temporal trends of palsa degradation and their relation to climate using linear regression. At both sites, the decrease in palsa area by −77 % to −90 % since 1959 and height by −16 % to −49 % since 2007 indicate substantial permafrost degradation throughout the study periods. The area loss rates are mainly connected to winter air temperature changes at Peera and winter precipitation changes at Laassaniemi. The active layer thickness (ALT) has varied annually between 2007 and 2021 with no significant trend and is related mainly to the number of very warm days during summer, autumn rainfall of previous year, and snow depths at Peera. At Laassaniemi, the ALT is weakly related to climate and has been decreasing in the middle part of the palsa during the past 8 years despite the continuous decrease in palsa volume. Our findings imply that the ALT in the inner parts of palsas do not necessarily reflect the overall permafrost conditions and underline the importance of surface position monitoring alongside the active layer measurements. The results also showed a negative relationship between the ALT and snow cover onset, indicating the complexity of climate–permafrost feedbacks in palsa mires

Exploring shoulder season greenhouse gas production along a permafrost thaw transect in sub-arctic Finnish Palsas

The future of terrestrial carbon found in permafrost is not yet well understood, but this soil carbon may be a potential significant contributor to positive-feedback loop of climatic warming. In the (sub)arctic, the annual freeze-thaw cycles and thick peat accumulation harbor ideal conditions for palsa formation. Although, a recent study at our site in Arctic Lapland found that the area of the carbon-rich palsa mounds have already decreased by -77 % to -90 % since 1960. Here, we investigate potential greenhouse gas (CO2, CH4, N2O) production from a palsa sampled along a transect with 60+ years of documented thaw. During the annual cycle of freeze-thaw, one of the largest unknowns in the life cycle of a palsa mound is the biogeochemical cycles during the shoulder season. This transition time between growing, and non-growing seasons that have previously been assumed to be times of relative dormancy for GHG flux in high-latitude wetlands. However, recent studies find that there is in fact a significant amount of GHG flux during this time. We aim to isolate shoulder season variables (increased N from plant senescence, temperature change) and explore how they each affect the potential CO2 and CH4 production using ex-situ incubations, coupled with microbial community cell counts sampled in tandem. Here, we test whether N addendums increase the GHG, as n-poor habitat has been shown to respond with increased microbial activity to the release of this metabolic bottleneck. In addition to the N-treatments, the samples will also be separated into three incubation temperature groups (4 , 15, 20C) to be able to link increasing temperatures with the N response. Overall, we aim to fill knowledge gaps on these habitats response to changing climatic conditions, and use our findings to better earth system models permafrost carbon predictions

The Permafrost-Agroecosystem Action Group: first results and future goals

Permafrost-agroecosystems encompass northern social-ecological systems which include both cultivation of arable permafrost-affected soils, and animal husbandry practices. These heterogeneous food and cultural systems are being affected by a warming climate. Examples include increasing opportunities for growing crops through longer growing seasons, as well as impacts on animals’ local and long-distance migratory movements and their food sources. Furthermore, climate change driven permafrost thaw and thaw accelerated by land clearance is rapidly changing the biophysical and socioeconomic aspects of these systems. Therefore, an international collaboration encompassing experts from North America, Europe and Asia is working on increasing our understanding of permafrost-agroecosystems and contributing to the adaptation, resilience, and sustainability strategy of these rapidly evolving systems. The International Permafrost Association Permafrost-Agroecosystem Action Group is composed of ~30 members from 7 countries. The objectives of our action group are to share knowledge and build networking capacities through meetings and webinar presentation as well as to collaborate on publications and produce the first geospatial dataset of permafrost-agroecosystems. Our poster presentation provides an overview of the group’s activities including providing case studies from a range of high-latitude and high-altitude areas as part of a group manuscript in preparation and an update on our mapping activities

Socioecological dynamics of diverse global permafrost-agroecosystems under environmental change

Permafrost-agroecosystems include all cultivation and pastoral activities in areas underlain by permafrost. These systems support local livelihoods and food production and are rarely considered in global agricultural studies but may become more relevant as climate change is increasing opportunities for food production in high latitude and mountainous areas. The exact locations and amount of agricultural production in areas containing permafrost are currently unknown, therefore we provide an overview of countries where both permafrost and agricultural activities are present. We highlight the socioecological diversity and complexities of permafrostagroecosystems through seven case studies: (1) crop cultivation in Alaska, USA; (2) Indigenous food systems and crop cultivation in the Northwest Territories, Canada; (3) horse and cattle husbandry and Indigenous hay production in the Sakha Republic, Russia; (4) mobile pastoralism and husbandry in Mongolia; (5) yak pastoralism in the Central Himalaya, Nepal; (6) berry picking and reindeer herding in northern Fennoscandia; and (7) reindeer herding in northwest Russia. We discuss regional knowledge gaps associated with permafrost and make recommendations to policy makers and land users for adapting to changing permafrost environments. A better understanding of permafrost-agroecosystems is needed to help sustainably manage and develop these systems considering rapidly changing climate, environments, economies, and industries

Reindeer use of low Arctic tundra correlates with landscape structure

Rapid climate change in Arctic regions is linked to the expansion of woody taxa (shrubification), and an increase in biomass as tundra becomes greener. Reindeer and caribou (Rangifer tarandus) are considered able to suppress vegetative greening through grazing and trampling. Quantifying reindeer use of different land cover types can help us understand their impact on the growth and recruitment of deciduous shrubs, many of which serve as fodder (e.g. Salix spp.), in favourable habitats, such as naturally denuded landslides in permafrost areas. Understanding the spatial distribution of reindeer pressure on vegetation is important to project future patterns of greening, albedo, snow capture, active layer development, and the overall resilience of tundra rangelands under ongoing climate change. Here we quantify reindeer habitat use within the low Arctic tundra zone of Yamal, West Siberia estimated from pellet-group counts, and also how active layer thickness (ALT) relates to reindeer use. Our results confirm intensive use by reindeer of terrain with high June-July time integrated normalised difference vegetation index, steeper slopes, ridges, upper slopes and valleys, and a preference for low erect shrub tundra. These sites also seem to have a shallower ALT compared to sites less used by reindeer, although we did not find any direct relationship between ALT and reindeer use. Low use of tall Salix habitats indicated that reindeer are unlikely to suppress the growth of already tall-erect woody taxa, while they exert maximum pressure in areas where shrubs are already low in stature, e.g. ridgetops. Reindeer ability to suppress the regrowth and expansion of woody taxa in landslide areas (i.e. concavities) seems limited, as these types were less used. Our results suggest that reindeer use of the landscape and hence their effects on the landscape correlates with the landscape structure. Future research is needed to evaluate the role and efficiency of reindeer as ecosystem engineers capable of mediating the effects of climate change

Permafrost degradation at two monitored palsa mires in north-west Finland

Funding Information: This research has been supported by the Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish Academy of Science and Letters, EU Horizon 2020 Research and Innovation Programme (grant no. 869471), the Academy of Finland (grant no. 330319, 338480, and 346602), and the Erasmus+ staff mobility programme. Publisher Copyright: © Author(s) 2023.Palsas and peat plateaus are expected to disappear from many regions, including Finnish Lapland. However, detailed long-Term monitoring data of the degradation process on palsas are scarce. Here, we present the results of the aerial photography time series analysis (1959-2021), annual real-Time kinematic (RTK) GNSS and active layer monitoring (2007-2021), and annual unoccupied aerial system surveys (2016-2021) at two palsa sites (Peera and Laassaniemi, 68gN) located in north-west Finland. We analysed temporal trends of palsa degradation and their relation to climate using linear regression. At both sites, the decrease in palsa area by-77g€¯% to-90g€¯% since 1959 and height by-16g€¯% to-49g€¯% since 2007 indicate substantial permafrost degradation throughout the study periods. The area loss rates are mainly connected to winter air temperature changes at Peera and winter precipitation changes at Laassaniemi. The active layer thickness (ALT) has varied annually between 2007 and 2021 with no significant trend andis related mainly to the number of very warm days during summer, autumn rainfall of previous year, and snow depths at Peera. At Laassaniemi, the ALT is weakly related to climate and has been decreasing in the middle part of the palsa during the past 8 years despite the continuous decrease in palsa volume. Our findings imply that the ALT in the inner parts of palsas do not necessarily reflect the overall permafrost conditions and underline the importance of surface position monitoring alongside the active layer measurements. The results also showed a negative relationship between the ALT and snow cover onset, indicating the complexity of climate-permafrost feedbacks in palsa mires.Peer reviewe