Palsas and peat plateaus occur in various environmental conditions, but their driving environmental factors have not been examined across the Northern Hemisphere with harmonized datasets. Such comparisons can deepen our understanding of these landforms and their response to climate change. We conducted a comparative study between four regions: Hudson Bay, Iceland, Northern Fennoscandia, and Western Siberia by integrating landform observations and geospatial data into a MaxEnt model. Climate and hydrological conditions were identified as primary, yet regionally divergent, factors affecting palsa and peat plateau occurrence. Suitable conditions for these landforms entail specific temperature ranges (500-1500 thawing degree days, 500-4000 freezing degree days), around 300 mm of rainfall, and high soil moisture accumulation potential. Iceland's conditions, in particular, differ due to higher precipitation, a narrower temperature range, and the significance of soil organic carbon content. The annual thermal balance is a critical factor in understanding the occurrence of permafrost peatlands and should be considered when comparing different regions. We conclude that palsas and peat plateaus share similar topographic conditions but occupy varying soil conditions and climatic niches across the Northern Hemisphere. These findings have implications for understanding the climatic sensitivity of permafrost peatlands and identifying potential greenhouse gas emitters.

Snow amounts and duration are susceptible to climate change and may significantly affect plant diversity and biomass in grassland ecosystems. Yet, the combined effects of grassland use (type and intensity) and snow depth on plant diversity and productivity remain poorly understood. We established two complementary field experiments to explore the mechanisms driving the effects of grassland use (type and intensity) and snow manipulation on plant diversity and productivity in the meadow steppe. An experiment on grassland use type and snow manipulation showed that lower snow cover in winter reduced soil moisture in the snowmelt period, significantly increased the abundance of ammonia-oxidizing archaea and ammonia-oxidizing bacteria, and initiated nitrification earlier, resulting in the loss of soil available nitrogen, and then reduced the aboveground biomass of early grasses. An experiment on grassland mowing intensity and snow manipulation showed that moderate mowing intensity can restrain the loss of grass biomass and soil nutrients and maintain grassland sustainability in winters with less snow. Stochasticity has played a more important role in plant community assembly in higher intensity of grassland use. Based on our results, we recommend that optimal defoliation height can restrain the loss of grass biomass and soil nutrients and maintain grassland sustainability in winters with less snow. This study has potential benefits for optimizing sustainable production and maintaining ecosystem function under winter snowfall changes in the future across large regions of arid and semiarid grasslands. (c) 2024 The Society for Range Management. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The burrowing activity of plateau pikas (Ochotona curzoniae; hereafter, pikas) may profoundly influence vegetation species composition on the Qinghai-Tibetan Plateau (QTP). Although significant efforts have been made to examine the relationship between vegetation species composition and pikas disturbance, our knowledge regarding the direct influence of pikas activity on vegetation species diversity is still limited. We conducted field observations on pikas burrows and surrounding vegetation patches at 23 alpine grassland sites to investigate this effect. When compared to vegetation patches, pikas burrowing activity decreased soil hardness, thus improving water infiltration, while caused the less reduction of soil nutrition and soil moisture when compared to adjacent vegetation patches. Vegetation species composition on pikas burrows significantly differed from that on vegetation patches. Common plant species between pikas burrows and vegetation patches were fewer than three in all types of grasslands, and ten species were found exclusively on pikas burrows. The total species richness, including both pikas burrows and vegetation patches, was approximately 1.3-2.5 times higher than that on each single patch type (pikas burrows or vegetation patches). A conceptual framework was proposed to synthesize the evolution of vegetation species composition under a disturbance regime resulting from pika's burrowing. Overall, we concluded that pika's burrowing activity enhanced vegetation species richness by loosening the soil, creating safe sites for seed settling and germination, which provided a novel habitat for vegetation invasion.

The active layer is the portion of soil overlaying the permafrost that freezes and thaws seasonally. It is a harsh habitat in which a varied and vigorous microbial population thrives. The high-altitude active layer soil in northern India is a unique and important cryo-ecosystem. However, its microbiology remains largely unexplored. It represents a unique reservoir for microbial communities with adaptability to harsh environmental conditions. In the Changthang region of Ladakh, the Tsokar area is a high-altitude permafrost-affected area situated in the southern part of Ladakh, at a height of 4530 m above sea level. Results of the comparison study with the QTP, Himalayan, Alaskan, Russian, Canadian and Polar active layers showed that the alpha diversity was significantly higher in the Ladakh and QTP active layers as the environmental condition of both the sites were similar. Moreover, the sampling site in the Ladakh region was in a thawing condition at the time of sampling which possibly provided nutrients and access to alternative nitrogen and carbon sources to the microorganisms thriving in it. Analysis of the samples suggested that the geochemical parameters and environmental conditions shape the microbial alpha diversity and community composition. Further analysis revealed that the cold-adapted methanogens were present in the Ladakh, Himalayan, Polar and Alaskan samples and absent in QTP, Russian and Canadian active layer samples. These methanogens could produce methane at slow rates in the active layer soils that could increase the atmospheric temperature owing to climate change.

Global warming leads to the melting of permafrost, affects changes in soil microbial community structures and related functions, and contributes to the soil carbon cycle in permafrost areas. Located at the southern edge of Eurasia's permafrost region, the Greater Khingan Mountains are very sensitive to climate change. Therefore, by analyzing the bacterial community structure, diversity characteristics, and driving factors of soil profiles (active surface layer, active deep layer, transition layer, and permafrost layer) in this discontinuous permafrost region, this research provides support for the study of the carbon cycling process in permafrost regions. The results show that the microbial diversity (Shannon index (4.81)) was the highest at 0-20 cm, and the Shannon index of the surface soil of the active layer was significantly higher than that of the other soil layers. Acidobacteria and Proteobacteria were the dominant bacteria in the active layer soil of the permafrost area, and Chloroflexi, Actinobacteria, and Firmicutes were the dominant bacteria in the permafrost layer. Chloroflexi made the greatest contribution to the bacterial community in the permafrost soil, and Bacteroidota made the greatest contribution to the bacterial community in the active surface soil. The structure, richness, and diversity of the soil bacterial community significantly differed between the active layer and the permafrost layer. The number of bacterial species was the highest in the active layer surface soil and the active layer bottom soil. The difference in the structure of the bacterial community in the permafrost soil was mainly caused by changes in electrical conductivity and soil-water content, while that in the active layer soil was mainly affected by pH and soil nutrient indices. Soil temperature, NO3--N, and pH had significant effects on the structure of the bacterial community. The active layer and permafrost soils were susceptible to environmental information processing and genetic information processing. Infectious disease: the number of bacterial species was significantly higher in the surface and permafrost layers than in the other layers of the soil. In conclusion, changes in the microbial community structure in soil profiles in discontinuous permafrost areas sensitive to climate change are the key to soil carbon cycle research.

Ongoing climate change threatens the biodiversity of glacier-fed river ecosystems worldwide through shifts in water availability and timing, temperature, chemistry, and channel stability. However, tropical glacier-fed rivers have received little attention compared to those in temperate and Arctic biomes, despite their unique biodiversity potentially responding differently due to additional stress from higher altitude locations thus lower oxygen availability, diurnal freeze-thaw cycles, and annual monsoon rainfall disturbances. However, tropical glacier-fed rivers have received little attention compared to those in temperate and Arctic biomes, despite their unique biodiversity potentially responding differently due to additional stress from higher altitude locations thus lower oxygen availability, diurnal freeze-thaw cycles, and annual monsoon rainfall disturbances. This study quantified aquatic biodiversity responses to decreasing glacier cover in the Cordillera Blanca range of the Peruvian Andes. Ten rivers were studied along a gradient of decreasing glacier cover in the Par & oacute;n, Huaytapallana, and Llanganuco basins, with a specific focus on macroinvertebrates and physicochemical parameters in both the dry and wet seasons. We found higher temperatures, more stable and lower turbidity rivers as glacier cover decreased, which were related significantly to higher local diversity and lower beta-diversity. Analysis of similarity revealed significant differences in the macroinvertebrate community among rivers with high, medium, or low glacier cover, illustrating turnover from specialists to generalists as glacial influence decreased. Redundancy analysis demonstrated that there were more species found to prefer stable beds and water temperatures in medium and low glacier cover in a catchment rivers. However, certain taxa in groups such as Paraheptagyia, Orthocladiinae, Anomalocosmoecus, and Limonia may be adapted to high glacial influence habitats and at risk of glacier retreat. Although species composition was different to other biomes, the Cordillera Blanca rivers showed similar benthic macroinvertebrate biodiversity responses to glacier retreat, supporting the hypothesis that climate change will have predictable effects on aquatic biodiversity in mountain ranges worldwide. Ongoing climate change threatens glacier-fed river ecosystems globally, impacting biodiversity through shifts in water availability, temperature, and chemistry. Tropical glacier-fed rivers, like those in the Peruvian Andes, are understudied despite unique stressors. This study examined biodiversity in 10 rivers along a glacier cover gradient. Results showed higher temperatures and stability as glacier cover decreased, correlating with increased local diversity. Analysis revealed turnover in macroinvertebrate communities with reduced glacial influence. Certain taxa may be vulnerable to glacier retreat. Despite differences from other regions, findings support predictable biodiversity responses to climate change in mountainous areas.image

The stability and effectiveness of the anaerobic digestion (AD) system are significantly influenced by temperature. While majority research has focused on the composition of the microbial community in the AD process, the relationships between functional gene profile deduced from gene expression at different temperatures have received less attention. The current study investigates the AD process of potato peel waste and explores the association between biogas production and microbial gene expression at 15, 25, and 35 degrees C through metatranscriptomic analysis. The production of total biogas decreased with temperature at 15 degrees C (19.94 mL/g VS), however, it increased at 35 degrees C (269.50 mL/g VS). The relative abundance of Petrimonas, Clostridium, Aminobacterium, Methanobacterium, Methanothrix, and Methanosarcina were most dominant in the AD system at different temperatures. At the functional pathways level 3, alpha-diversity indices, including Evenness (Y = 5.85x + 8.85; R-2 = 0.56), Simpson (Y = 2.20x + 2.09; R-2 = 0.33), and Shannon index (Y = 1.11x + 4.64; R-2 = 0.59), revealed a linear and negative correlation with biogas production. Based on KEGG level 3, several dominant functional pathways associated with Oxidative phosphorylation (ko00190) (25.09, 24.25, 24.04%), methane metabolism (ko00680) (30.58, 32.13, and 32.89%), and Carbon fixation pathways in prokaryotes (ko00720) (27.07, 26.47, and 26.29%), were identified at 15 degrees C, 25 degrees C and 35 degrees C. The regulation of biogas production by temperature possibly occurs through enhancement of central function pathways while decreasing the diversity of functional pathways. Therefore, the methanogenesis and associated processes received the majority of cellular resources and activities, thereby improving the effectiveness of substrate conversion to biogas. The findings of this study illustrated the crucial role of central function pathways in the effective functioning of these systems.

The seasonal movement of the zero-degree isotherm across the Southern Ocean and Antarctic Peninsula drives major changes in the physical and biological processes around maritime Antarctica. These include spatial and temporal shifts in precipitation phase, snow accumulation and melt, thawing and freezing of the active layer of the permafrost, glacier mass balance variations, sea ice mass balance and changes in physiological processes of biodiversity. Here, we characterize the historical seasonal southward movement of the monthly near-surface zero-degree isotherm latitude (ZIL), and quantify the velocity of migration in the context of climate change using climate reanalyses and projections. From 1957 to 2020, the ZIL exhibited a significant southward shift of 16.8 km decade(-1) around Antarctica and of 23.8 km decade(-1) in the Antarctic Peninsula, substantially faster than the global mean velocity of temperature change of 4.2 km decade(-1), with only a small fraction being attributed to the Southern Annular Mode (SAM). CMIP6 models reproduce the trends observed from 1957 to 2014 and predict a further southward migration around Antarctica of 24 +/- 12 km decade(-1) and 50 +/- 19 km decade(-1) under the SSP2-4.5 and SSP5-8.5 scenarios, respectively. The southward migration of the ZIL is expected to have major impacts on the cryosphere, especially on the precipitation phase, snow accumulation and in peripheral glaciers of the Antarctic Peninsula, with more uncertain changes on permafrost, ice sheets and shelves, and sea ice. Longer periods of temperatures above 0 degrees C threshold will extend active biological periods in terrestrial ecosystems and will reduce the extent of oceanic ice cover, changing phenologies as well as areas of productivity in marine ecosystems, especially those located on the sea ice edge.

All ecosystems face ecological challenges in this century. Therefore, it is becoming increasingly important to understand the ecology and degree of local adaptation of functionally important Arctic-alpine biomes by looking at the most diverse taxon of metazoans: the Arthropoda. This is the first study to utilize metabarcoding in the Alpine tundra, providing insights into the effects of micro-environmental parameters on alpha- and beta-diversity of arthropods in such unique environments. To characterize arthropod diversity, pitfall traps were set at three middle-alpine sampling sites in the Scandinavian mountain range in Norway during the snow-free season in 2015. A metabarcoding approach was then used to determine the small-scale biodiversity patterns of arthropods in the Alpine tundra. All DNA was extracted directly from the preservative EtOH from 27 pitfall traps. In order to identify the controlling environmental conditions, all sampling locations were equipped with automatic data loggers for permanent measurement of the microenvironmental conditions. The variables measured were: air temperature [degrees C] at 15 cm height, soil temperature [degrees C] at 15 cm depth, and soil moisture [vol.%] at 15 cm depth. A total of 233 Arthropoda OTUs were identified. The number of unique OTUs found per sampling location (ridge, south-facing slope, and depression) was generally higher than the OTUs shared between the sampling locations, demonstrating that niche features greatly impact arthropod community structure. Our findings emphasize the fine-scale heterogeneity of arctic-alpine ecosystems and provide evidence for trait-based and niche-driven adaptation. The spatial and temporal differences in arthropod diversity were best explained by soil moisture and soil temperature at the respective locations. Furthermore, our results show that arthropod diversity is underestimated in alpine-tundra ecosystems using classical approaches and highlight the importance of integrating long-term functional environmental data and modern taxonomic techniques into biodiversity research to expand our ecological understanding of fine- and meso-scale biogeographical patterns. Our study examines the alpha- and beta-diversity of arthropods in the Arctic-alpine biomes of the Scandes using environmental DNA (eDNA)/metabarcoding. We found that micro-climatological parameters such as air/soil temperature and soil moisture significantly influence the arthropod community structure, highlighting the fine-scale heterogeneity of these ecosystems. Our study emphasizes the importance of integrating long-term functional environmental data and modern taxonomic techniques to accurately assess arthropod diversity and broaden our understanding of biogeographical patterns in alpine-tundra ecosystems.image

The retreat of glaciers in Antarctica has increased in the last decades due to global climate change, influencing vegetation expansion, and soil physico-chemical and biological attributes. However, little is known about soil microbiology diversity in these periglacial landscapes. This study characterized and compared bacterial and fungal diversity using metabarcoding of soil samples from the Byers Peninsula, Maritime Antarctica. We identified bacterial and fungal communities by amplification of bacterial 16 S rRNA region V3-V4 and fungal internal transcribed spacer 1 (ITS1). We also applied 14C dating on soil organic matter (SOM) from six profiles. Physicochemical analyses and attributes associated with SOM were evaluated. A total of 14,048 bacterial ASVs were obtained, and almost all samples had 50% of their sequences assigned to Actinobacteriota and Proteobacteria. Regarding the fungal community, Mortierellomycota, Ascomycota and Basidiomycota were the main phyla from 1619 ASVs. We found that soil age was more relevant than the distance from the glacier, with the oldest soil profile (late Holocene soil profile) hosting the highest bacterial and fungal diversity. The microbial indices of the fungal community were correlated with nutrient availability, soil reactivity and SOM composition, whereas the bacterial community was not correlated with any soil attribute. The bacterial diversity, richness, and evenness varied according to presence of permafrost and moisture regime. The fungal community richness in the surface horizon was not related to altitude, permafrost, or moisture regime. The soil moisture regime was crucial for the structure, high diversity and richness of the microbial community, specially to the bacterial community. Further studies should examine the relationship between microbial communities and environmental factors to better predict changes in this terrestrial ecosystem.