Temperate Mountain Research Articles

Behavioural thermoregulation prevents thermal stress in lizard sperm fertility

Global warming is threatening ectotherms, with strong repercussions on their population dynamics. Body temperature in ectotherm reptiles is crucial to perform all their biological functions, which are maximized within a narrow interval. When faced with new or adverse thermal conditions, reptiles will respond with distributional changes, behavioural adjustments to maintain their internal temperature, or by adapting to the new environment, otherwise, extinctions will occur. Higher temperatures may have negative repercussions, for example, shortening periods of activity, affecting embryo development during gestation or decreasing viability of sperm cells in males. Through behavioural thermoregulation, reptiles can compensate for environmental variations (Bogert effect). Furthermore, according to Janzen’s hypothesis, the physiological cost of responding to adverse thermal conditions will be low in species exposed to higher thermal overlap. Here, we analysed the effect of a change in the thermal regime on sperm cell viability in Sceloporus megalepidurus, a small viviparous lizard from central Mexico. We hypothesized that an active thermoregulator inhabiting temperate mountains is able to prevent the effects of thermal change on sperm cell viability. We found that the change in thermal regime did not modify sperm cell viability, nor does it affect the maturation of sperm cells in the epididymis. Our results support the Bogert effect and suggest that, despite the high temperatures and low thermal quality, S. megalepidurus can maintain its body temperature within an optimal range for sperm cell viability.

Differences in Soil CO2 Efflux and Microbial Community Composition among Slope Aspects in a Mountain Oak Forest

As one of the main terrain factors, the slope aspect generally shows remarkable effects on microclimate and vegetation distribution. The purpose of this study was to determine the potential effects of the slope aspect on soil respiration and the soil microbial community in a temperate mountain forest. A field investigation was carried out in a mountain oak forest located at different slope aspects (northeast, northwest, southeast, and southwest), and soil respiration was continuously measured for 12 months. The soil’s bacterial and fungal taxa were analyzed during the growing season. Our results showed that average soil respiration on the southwest and southeast slope aspects was 72.9% higher than the average on the northeast and northwest slope aspects. The coefficient of variation of soil respiration had the highest value on the northwest aspect (20.9%) and the lowest value on the southeast aspect (6.9%). The southeast slope had significantly higher soil respiration and temperature sensitivity compared to the other three slope aspects. The slope aspect substantially affected the soil’s bacterial and fungal r/K strategy, showing the lowest values on the northwest aspect and the highest values on the southeast aspect. Differences in bacterial r/K, the ratio of microbial biomass carbon (MBC) to soil organic carbon (SOC), and SOC among slope aspects contributed to a 43%, 38%, and 32% variation in soil respiration, respectively. The variation of soil temperature across slope aspects showed an indirect effect on soil respiration through changing bacterial r/K and MBC/SOC. Our findings highlight that terrain plays a critical role in regulating the spatial heterogeneity of soil respiration in mountain forests, which could be explained by the differences in SOC and microbial community composition across slope aspects.

Methane concentration in the heartwood of living trees in a cold temperate mountain forest: variation, transport and emission.

Forest soils are the largest terrestrial sink of methane (CH4), but CH4 produced in tree trunks by methanogenic archaea and emitted into the atmosphere can significantly offset CH4 oxidation in the soil. However, our mechanistic understanding of CH4 accumulation in tree trunks, in relation to CH4 emission from the trunk surface, is still limited. We characterized temporal variations in the molar fraction of CH4 in the heartwood of trees ([CH4]HW) of four different species in a mountain forest and addressed the relationship between [CH4]HW and emission from the surface of the trunk (${F}_{CH_4}$), in connection with the characteristics of the wood. [CH4]HW measurements were made monthly for 15 months using gas-porous tubes permanently inserted into the trunk. [CH4]HW were above ambient CH4 molar fraction for all trees, lower than 100p.p.m. for seven trees, higher for the nine other trees and greater than 200,000p.p.m. (>20%) for two of these nine trees. [CH4]HW varied monthly but were not primarily determined by trunk temperature. Heartwood diffusive resistance for CH4 was variable between trees, not only due to heartwood characteristics but probably also related to source location. ${F}_{CH_4}$were weakly correlated with [CH4]HW measured a few days after. The resulting apparent diffusion coefficient was also variable between trees suggesting variations in the size and location of the CH4 production sites as well as resistance to gas transport within the trunk. Our results highlight the challenges that must be overcome before CH4 emissions can be simulated at the tree level.

Habitat Loss in the IUCN Extent: Climate Change-Induced Threat on the Red Goral (Naemorhedus baileyi) in the Temperate Mountains of South Asia.

Climate change has severely impacted many species, causing rapid declines or extinctions within their essential ecological niches. This deterioration is expected to worsen, particularly in remote high-altitude regions like the Himalayas, which are home to diverse flora and fauna, including many mountainous ungulates. Unfortunately, many of these species lack adaptive strategies to cope with novel climatic conditions. The Red Goral (Naemorhedus baileyi) is a cliff-dwelling species classified as "Vulnerable" by the IUCN due to its small population and restricted range extent. This species has the most restricted range of all goral species, residing in the temperate mountains of northeastern India, northern Myanmar, and China. Given its restricted range and small population, this species is highly threatened by climate change and habitat disruptions, making habitat mapping and modeling crucial for effective conservation. This study employs an ensemble approach (BRT, GLM, MARS, and MaxEnt) in species distribution modeling to assess the distribution, habitat suitability, and connectivity of this species, addressing critical gaps in its understanding. The findings reveal deeply concerning trends, as the model identified only 21,363 km2 (13.01%) of the total IUCN extent as suitable habitat under current conditions. This limited extent is alarming, as it leaves the species with very little refuge to thrive. Furthermore, this situation is compounded by the fact that only around 22.29% of this identified suitable habitat falls within protected areas (PAs), further constraining the species' ability to survive in a protected landscape. The future projections paint even degraded scenarios, with a predicted decline of over 34% and excessive fragmentation in suitable habitat extent. In addition, the present study identifies precipitation seasonality and elevation as the primary contributing predictors to the distribution of this species. Furthermore, the study identifies nine designated transboundary PAs within the IUCN extent of the Red Goral and the connectivity among them to highlight the crucial role in supporting the species' survival over time. Moreover, the Dibang Wildlife Sanctuary (DWLS) and Hkakaborazi National Park are revealed as the PAs with the largest extent of suitable habitat in the present scenario. Furthermore, the highest mean connectivity was found between DWLS and Mehao Wildlife Sanctuary (0.0583), while the lowest connectivity was observed between Kamlang Wildlife Sanctuary and Namdapha National Park (0.0172). The study also suggests strategic management planning that is a vital foundation for future research and conservation initiatives, aiming to ensure the long-term survival of the species in its natural habitat.

I funghi della foresta dei Bagni di Masino (Sondrio, Italia). Osservazioni micofloristiche, fenologiche ed ecologiche

The results of the three-year survey (2019−2021) of the macromycetes of the “Val Masino - Bagni” Regional Forest, located in the eastern Rhaetian Alps, Bernina Alps subsection, are presented. The geographical, geological, geomorphological, pedological and vegetational characteristics are briefly illustrated. The local weather-climatic conditions were processed on the basis of daily temperature, precipitation and relative humidity data measured in the three-year period 2019-2021 from the nearest ARPA station (Val Masino - San Martino). The survey area, between 1100 and about 1300 m a.s.l., was divided into 11 homogeneous stations for geographical and vegetational characteristics, of which one in beech forest (Habitat EUNIS T18 - Fagus forest on acid soils), four in spruce forests (Habitat EUNIS T31 - Temperate mountain Picea forest), one in pastured clearing (Habitat EUNIS R57 - Herbaceous forest clearing vegetation), four in secondary pastures (Habitat EUNIS R21 - Mesic permanent pasture of lowlands and mountains) and one in anthropized area (dirt road, flowerbeds, parking lots). The survey led to the identification of 354 ma-cromycetes, to which a further 43 must be added, found in previous years by the members of the Mycological Group Cantù and Como. In total 397 macromycetes are currently known for the investigated area, of which 94.4% belong to the phylum Basidiomycota (375 species/varieties, 155 genera) and 5.6% to the phylum Ascomycota (22 species, 17 genera). 57 species/varieties (54 Basidiomycota and 3 Ascomycota) are reported for the first time for the province of Sondrio: Aleurodiscus amorphus, Ama-nita brunneofuliginea, A. spadicea, Amylostereum chailletii, Buchwaldoboletus lignicola, Connopus acervatus, Corticium meridioroseum, Cortinarius cinnabarinus, C. livido-ochraceus, C. torvus, Cylindrobasi-dium evolvens, Cystoderma jasonis, Cystodermella terryi, Faerberia carbonaria, Ganoderma resinaceum, Gymnopus hariolorum, Helvella bicolor, Homophron cernuum, Hydnotrya cerebriformis, Hygrophorocybe nivea, Hygrophorus unicolor, Hypholoma epixanthum, Lachnellula subtilissima, Lactarius albocarneus, L. subdulcis, Laxitextum bicolor, Lentinus substrictus, Lycoperdon echinatum, Mycena fagetorum, M. pelianthina, M. renati, Neoantrodia serialis, Neofavolus suavissimus, Panaeolus olivaceus, Panellus violaceofulvus, Phlebiopsis gigantea, Phylloporus pelletieri, Picipes melanopus, Pluteus salicinus, Polyporus tuberaster, Porostereum spadiceum, Postia tephroleuca, Psathyrella fagetophila, P. spintrigeroides, P. tephrophylla, Pycnoporellus fulgens, Ramaria stricta, Rhizocybe pruinosa, Rigidoporus sanguinolentus, Russula cavipes, R. farinipes, R. olivacea, Steccherinum fimbriatum, Stereum gausapatum, Tricholoma album, T. ustale, Xerocomellus pruinatus. A comparison with the Red List of threatened macromycetes in Switzerland shows that 31 species considered threatened were found in the survey area, equal to 7.8% of the total, of which one (Mycena fagetorum) belonging to the CR category (Critically Endangered), 3 to category EN (Endangered), 18 to category VU (Vulnerable) and 9 to category NT (Nearly Threatened). The phenological analysis, conducted excluding the 50 li-gnicolous taxa (Polyporaceae s.l. and Corticiaceae s.l.) whose fruiting bodies can persist in the environment from a few months to a few years and therefore alter the results, reveals that the month with the greatest mycological diversity is September with 237 taxa out of 347, equal to 68.3%, followed by October (145, 41.8%), July (99, 28.4%) and August (94, 26.9%). According to the season of discovery, the exclusively autumnal macromycetes (September, October and November) are 170, the exclusively estival ones (June, July and August) are 44 and those exclusively vernal (March, April and May) are 11. The evaluation of the ecosystemic health status of the forest habitats of the investigated area (stations 1−5), based on the spectra of trophic groups (biotrophic, ectomycorrhizal, mycoparasite, parasite, saprotrophic, sapro-ectomycorrhizal and sapro-parasite), shows that only station 4 (outside the borders of the Regional Forest) presents a percentage value of ectomycorrhizal species indicating a phase of acute disturbance (36.9%), while all the others show a good state of health with values between 49.6% (station 1) and 54% (station 5). In the investigated area, some species indicating degradation processes already underway (Megacollybia platyphylla, Clitocybe phaeophthalma and Apioperdon pyriforme) and future (Mycena amicta, M. galericulata, M. pelianthina and M. pura) were found. In addition, the comparison of the percentage of ectomycorrhizal macromycetes surveyed within the two fenced areas located within the station 2 (73.8%) with that of the station 2 as a whole (51.2%) shows how the anthropic disturbance, resulting from the high tourist attendance (many thousands of people every year, mostly concentrated in the months from May to September), has consequences not only on the vegetation, but also on the growth and distribution of the mycoflora. Finally, lignicolous, beech forest and grassland habitats ma-cromycetes are taken into consideration, with some observations on taxa considered of particular interest or rarity. In particular, the mycoflora of the beech forest is analyzed in detail, given that this habitat constitutes the most valuable element of the investigated area. Of the 354 taxa surveyed in the three-year period 2019−2021, those that, on the basis of the literature consulted, can be considered more or less closely associated with beech are 40, of which 13 exclusive and 27 preferential.

How does tourist development influence traditional mountain landscapes? A case study from the Western Beskids, Poland

In many mountainous regions, ongoing reforestation leads to the permanent shrinkage of traditional landscapes connected with past human activity. Tourism is often perceived as a measure for the protection of traditional landscapes. Nevertheless, there is still a lack of in-depth studies exploring the connection between mountain glade conservation and tourism development. This paper aimed to determine whether tourism development can prevent the reforestation of temperate mountain glades and to assess the extent of its influence on traditional glade landscapes. Based on the example of the Western Beskids (Poland), we investigated the change in the range of glades in relation to tourist development, which has not been analysed until now. Cartographic analyses were used to examine how the landscape has changed since 1983. To determine the influence of tourist development on the landscape, the tourism landscape footprint (TLF) index was calculated. Two trends were detected: reforestation in glades that are touristically utilized and the gradual tourist development of the remnants of traditional landscapes within preserved non-forested areas. The study reveals that despite tourism, reforestation within glades is continuing, and simultaneously, the share of tourist elements in the shrinking glades is increasing. In the case of areas intensively used for tourism, the traditional landscape is disappearing as it is transformed into a tourist landscape. Further studies are necessary to assess the level of tourism development that will provide traditional landscape conservation in accordance with the principles of sustainable development.

Temporal-Spatial Fluctuations of a Phytoplankton Community and Their Association with Environmental Variables Based on Classification and Regression Tree in a Shallow Temperate Mountain River.

The effects of environmental factors on phytoplankton are not simply positive or negative but complex and dependent on the combination of their concentrations in a fluctuating environment. Traditional statistical methods may miss some of the complex interactions between the environment and phytoplankton. In this study, the temporal-spatial fluctuations of phytoplankton diversity and abundance were investigated in a shallow temperate mountain river. The machine learning method classification and regression tree (CART) was used to explore the effects of environmental variables on the phytoplankton community. The results showed that both phytoplankton species diversity and abundance varied fiercely due to environmental fluctuation. Microcystis aeruginosa, Amphiprora sp., Anabaena oscillarioides, and Gymnodinium sp. were the dominant species. The CART analysis indicated that dissolved oxygen, oxidation-reduction potential, total nitrogen (TN), total phosphorus (TP), and water temperature (WT) explained 36.00%, 13.81%, 11.35%, 9.96%, and 8.80%, respectively, of phytoplankton diversity variance. Phytoplankton abundance was mainly affected by TN, WT, and TP, with variance explanations of 39.40%, 15.70%, and 14.09%, respectively. Most environmental factors had a complex influence on phytoplankton diversity and abundance: their effects were positive under some conditions but negative under other combinations. The results and methodology in this study are important in quantitatively understanding and exploring aquatic ecosystems.

Near-Complete Sampling of Forest Structure from High-Density Drone Lidar Demonstrated by Ray Tracing

Drone lidar has the potential to provide detailed measurements of vertical forest structure throughout large areas, but a systematic evaluation of unsampled forest structure in comparison to independent reference data has not been performed. Here, we used ray tracing on a high-resolution voxel grid to quantify sampling variation in a temperate mountain forest in the southwest Czech Republic. We decoupled the impact of pulse density and scan-angle range on the likelihood of generating a return using spatially and temporally coincident TLS data. We show three ways that a return can fail to be generated in the presence of vegetation: first, voxels could be searched without producing a return, even when vegetation is present; second, voxels could be shadowed (occluded) by other material in the beam path, preventing a pulse from searching a given voxel; and third, some voxels were unsearched because no pulse was fired in that direction. We found that all three types existed, and that the proportion of each of them varied with pulse density and scan-angle range throughout the canopy height profile. Across the entire data set, 98.1% of voxels known to contain vegetation from a combination of coincident drone lidar and TLS data were searched by high-density drone lidar, and 81.8% of voxels that were occupied by vegetation generated at least one return. By decoupling the impacts of pulse density and scan angle range, we found that sampling completeness was more sensitive to pulse density than to scan-angle range. There are important differences in the causes of sampling variation that change with pulse density, scan-angle range, and canopy height. Our findings demonstrate the value of ray tracing to quantifying sampling completeness in drone lidar.

Ubiquity of methanogenic archaea in the trunk of coniferous and broadleaved tree species in a mountain forest.

Wetwood of living trees is a habitat of methanogenic archaea, but the ubiquity of methanogenic archaea in the trunk of various trees has not been revealed. The present study analysed methanogenic archaeal communities inside coniferous and broadleaved trees in a cold temperate mountain forest by culture-dependent or independent techniques. Heartwood and sapwood segments were obtained from the trunk of seven tree species, Cryptomeria japonica, Quercus crispula, Fraxinus mandshurica, Acer pictum, Aesculus turbinata, Magnolia obovata, and Populus tremula. Amplicon sequencing analysis of 16S rRNA genes showed that Methanobacteriaceae predominated the archaeal communities and Methanomassiliicoccaceae also inhabited some trees. Real-time PCR analysis detected methanogenic archaeal mcrA genes from all the tree species, with a maximum of 107copiesg-1 dry wood. Digital PCR analysis also detected mcrA genes derived from Methanobacterium spp. and Methanobrevibacter spp. from several samples, with a maximum of 105 and 104copiesg-1 dry wood. The enumeration by the most probable number method demonstrated the inhabitation of viable methanogenic archaea inside the trees; 106cellsg-1 dry wood was enumerated from a heartwood sample of C. japonica. Methanogenic archaea related to Methanobacterium beijingense were cultivated from a heartwood sample of Q. crispula and F. mandshurica. The present study demonstrated that the inside of various trees is a common habitat for methanogenic archaeal communities and a potential source of methane in forest ecosystems.

Dispersal limitations and ecological adaptions shape phylogenetic diversity patterns of angiosperm woody plant communities along latitudinal and elevational gradients in East Asian islands

For centuries, ecologists have been captivated by the assembly of local communities from regional species pools, which gives rise to spatial diversity patterns. This study focused on hierarchical filtering process, which involves dispersal limitation and climatic constraint across regional to local scale, that underpins plant biodiversity patterns in East Asian islands, as one of the biodiversity hotspots with high endemicity. We used vegetation and species pool datasets of angiosperm woody plant communities collected from seven mountains across Japan to Taiwan to explore the relative contributions of local factors of individual plots, islands, latitude, elevation, and climatic variables related to the pattern of phylogenetic community assembly. Using linear regression and variation partitioning, we found that the island factor had the strongest filtering effect followed by latitude. Elevation and local factors (slope, aspect) accounted for a very small proportion of the variance in phylogenetic dispersion and community clade age between member species. Geographical factors involving islands, distance, and elevation had overriding filtering effects over climatic factors (minimum temperature of the coldest month, precipitation of the driest month) in shaping woody plant assembly patterns at the regional scale across East Asia islands. Tropical niche conservatism contributed to shaping woody plant communities in temperate region and high elevational regions on subtropical mountains as young and closely related species coexisted in those regions due to their adaptation to cold climates. This also explained the minor climate effects on species sorting in temperate mountains characterized by temperate-specific species pool which had already been filtered by cold climates. Inconsistent elevational phylogenetic diversity patterns in East Asia islands suggest a mountain-specific process that governs community assembly along elevational gradients, likely attributed to the location and climate of the mountain. These results suggest that historical factors (geohistorical isolation) related to islands and mountains contribute to in situ diversification that shaped plant diversity gradient from subtropical to temperate forests.

Same, but different: similar states of forest structure in temperate mountain regions of Europe despite different social-ecological forest disturbance regimes

ContextEcosystem services provided by mountain forests are critically linked to forest structure. Social-ecological disturbance regimes (i.e., the rate, frequency, and patch size distribution of disturbances driven by interacting natural and anthropogenic processes) and land use affect forest structure, but their specific impacts are not fully understood.ObjectivesWe examine how differences in disturbance regimes affect patterns of forest structure across three European mountain ranges with similar vegetation types but different land-use histories: the European Alps, the Carpathians, and the Caucasus.MethodsWe related data on horizontal and vertical forest structure, measured by spaceborne lidar (GEDI), with Landsat-derived information on forest disturbances (1986–2020) and topographic, climatic, and anthropogenic predictors.ResultsWe found similar social-ecological disturbance regimes in the Alps and Carpathians (average annual disturbance rates of 0.34% and 0.39%, respectively, and median patch size < 0.5 ha), yet much lower disturbance rates and patch sizes in the Caucasus (0.08% yr−1 and < 0.2 ha). Despite different disturbance regimes, we found similar patterns of forest structure. Two alternative states emerged consistently across all mountain ranges: a tall and closed-canopy state in 74–80% of forests and a low and open-canopy state (< 50% canopy cover) in the rest. While forest structure responded consistently to abiotic drivers such as topography and climate, its association with anthropogenic pressures differed between mountain ranges. Stand-replacing disturbances played an important role in the Carpathians, while forest structure in the Caucasus was related to proximity to settlements, reflecting local forest use.ConclusionsDifferent social-ecological contexts in mountain regions can produce markedly different forest disturbance regimes. Despite these differences, similar states of forest structures emerge, suggesting strong attractors of structure in temperate mountain forests.

Gap expansion is the dominant driver of canopy openings in a temperate mountain forest landscape

Abstract Natural disturbances are important drivers of forest dynamics, and canopy gaps are their fingerprints in forest ecosystems. Gaps form and persist because of the interplay of tree mortality and regeneration. They can have long‐lasting impacts on ecosystems, yet the temporal dynamics of gap formation and closure remains poorly quantified. We analysed 11,331 canopy gaps and their changes through time across 3999 ha of unmanaged temperate mountain forests at Berchtesgaden National Park (Germany). We assessed gap formation and closure using three repeat lidar acquisitions between 2009 and 2021, analysing canopy height changes at 1 m horizontal resolution. Our objective was to determine the dominant mode of gap formation, distinguishing the creation of new gaps from the expansion of existing ones. Additionally, we studied the rate of gap closure, considering closure from tree regeneration and lateral crown expansion. Gap formation was primarily driven by gap expansion rather than the initiation of new gaps. Gap expansion accounted for 81.3% of gap formation, although new gaps were on average twice as large as gap expansions. Only 1.4% of gaps did not expand over the 12‐year study period, and Norway spruce forests had the highest rate of gap expansion. Overall, gap closure rate (0.74 ha 100 ha−1 year−1) was higher than gap formation (0.58 ha 100 ha−1 year−1) in our study system. Ingrowth of the regenerating tree cohort was the primary mode of gap closure, with lateral crown expansion accounting for 20% of all gap area closed. Mixed‐species stands had the highest rate of gap closure, and gaps &lt;0.1 ha closed faster than larger gaps. Synthesis. While canopy openings are generally small in the European Alps, we show that they keep growing over multiple years, underlining that gap expansion is an important driver of temperate forest dynamics. Canopy gaps closed faster than they were created, highlighting the resilience of European mountain forests to natural disturbances. However, as disturbances are projected to increase under climate change, this resilience might be challenged in the future, requiring a continuous monitoring of gap dynamics as an important early warning indicator of forest change.

Changes in temperature sensitivity of forest litter during decomposition along an altitudinal gradient in temperate mountains – A reciprocal litter transplantation study

The aim of this study was to assess the effects of the factors controlling the temperature sensitivity of litter decomposition, which is essential for predicting the rate of soil carbon loss in in the context of global climate changes. It based on the translocation of forest litter in a field experiment conducted in the Western Carpathians. Litterbags were used to expose litter originating from different altitudes (i.e., 600, 900, and 1200 m a.s.l.) at the altitude where it was collected and at two other altitudes on five different mountains. Litterbags were collected after 6, 10, and 24 months of exposure. The respiration rate of litter was measured in the laboratory, and Q10 coefficients were evaluated for two temperature ranges: lower (Q10L; 5 °C–15 °C) and higher (Q10H; 15 °C–25 °C). We tested whether litter Q10 values correlated with experimental factors, as well as soil and microbial community properties. After 24 months of exposure, the litter mass decreased to half of its initial mass. The general linear model (GLM) constructed for Q10 (R2adj = 77.3 %; p < 0.0001) indicated, that Q10L values were higher than Q10H values (2.19 ± 0.58 and 1.52 ± 0.31, respectively) and increased strongly with time (1.56 ± 0.36, 1.73 ± 0.45, and 2.36 ± 0.60, consecutively). There was a significant interaction between the temperature range and time, indicating that Q10L increased more over time than Q10H. Other interaction between temperature range and litter origin indicated that Q10L increased with the altitude of the litter origin, whereas Q10H did not change. The proportion of fungi in the microbial biomass correlated positively with Q10. Our results were consistent with the kinetic theory of higher temperature sensitivity for more decomposed organic matter. The conclusion that litter Q10L is more responsive to environmental conditions than Q10H has important implications for estimating soil carbon emissions.

The interior climate and its microclimatic variation of temperate forests in Northern Patagonia, Argentina

Knowledge on mesoclimatic zonation and microclimatic variations within mountain forest ecosystems is crucial for understanding regional species turnover and effects of climate change on these systems. The temperate mountain forests in the Andean region of South America are among the largest and contiguous natural deciduous forest areas in the world. Due to their pronounced disturbance regime and different successional stages, a climatic zonation combined with the characterisation of its microclimatic variation is important to identify thresholds of species occurrences.We used micro-loggers to measure air temperature and relative humidity for one year at 40 measurement locations along longitudinal and elevation gradients in mountain forests in Northern Patagonia, Argentina. Our results unveil mesoclimatic patterns within these forests characterised by variations in temperature and vapour pressure deficit along the elevational gradient in general, but also at different times of the year. For example, Austrocedrus chilensis and Nothofagus dombeyi forests differed mainly by temperature and its diurnal range in the warmest months of the year. Also, differences between forest stands and gaps were more pronounced in the warmest months of the year and at lower elevations, with up to 2.5 K higher temperatures in the second half of the day in gaps. We found clear indications that shrubland of Nothofagus antarctica representing a successional stage after disturbances alters the mesoclimatic pattern, favouring forest fire ignition. Such mesoclimatic variations have a major influence on tree species turnover and ecological processes within these forest ecosystems.The findings contribute to our understanding of the complex interplay between topography, climate, and vegetation in shaping the spatial patterns of species occurrences.

Tree structure and diversity shape the biomass of primary temperate mountain forests

Primary forests are spatially diverse terrestrial ecosystems with unique characteristics, being naturally regenerative and heterogeneous, which supports the stability of their carbon storage through the accumulation of live and dead biomass. Yet, little is known about the interactions between biomass stocks, tree genus diversity and structure across a temperate montane primary forest. Here, we investigated the relationship between tree structure (variability in basal area and tree size), genus-level diversity (abundance, tree diversity) and biomass stocks in temperate primary mountain forests across Central and Eastern Europe. We used inventory data from 726 permanent sample plots from mixed beech and spruce across the Carpathian Mountains. We used nonlinear regression to analyse the spatial variability in forest biomass, structure, and genus-level diversity and how they interact with plot-level tree age, disturbances, temperature and altitude. We found that the combined effects of genus and structural indices were important for addressing the variability in biomass across different spatial scales. Local processes in disturbance regimes and uneven tree age support forest heterogeneity and the accumulation of live and dead biomass through the natural regeneration, growth and decay of the forest ecosystem. Structural complexities in basal area index, supported by genus-level abundance, positively influence total biomass stocks, which was modulated by tree age and disturbances. Spruce forests showed higher tree density and basal area than mixed beech forests, though mixed beech still contributes significantly to biomass across landscapes. Forest heterogeneity was strongly influenced by complexities in forest composition (tree genus diversity, structure). We addressed the importance of primary forests as stable carbon stores, achieved through structure and diversity. Safeguarding such ecosystems is critical for ensuring the stability of the primary forest, carbon store and biodiversity into the future.

Microbial carbon and nitrogen limitation in Larix gmelinii forests along an altitudinal gradient: Evidence from ecoenzymatic stoichiometry and vector analysis

Mountain ecosystems have obvious variations in environmental factors at small spatial scales and thus provide a natural platform for investigating climate change. To investigate the characteristics of extracellular enzymes and microbial metabolic limitations in the hostile environmental conditions of cold temperate mountain ecosystems, soil physicochemical properties and enzyme activities were measured in the 0–10 cm and 10–20 cm soil layers of Larix gmelinii forests at elevations of 830 m, 950 m, 1100 m, and 1300 m. Our results showed that altitude and soil depth had a significant effect on 1,4-β-glucosidase, 1,4-β-N-acetyl-glucosaminidase, leucine aminopeptidase, and acid phosphatase activities. Extracellular enzyme activities decreased with increasing altitude and soil depth. The stoichiometric ratio of soil C-, N-, and P-acquiring enzymes after logarithmic transformation was 1:1.27:0.72 across all altitudes and soil depths. The metabolism of the microorganisms was mainly limited by C and N, and a high C limitation was observed at higher-altitude sites. With increased soil depth, the N limitation gradually weakened. Moreover, soil bulk density and pH were the main factors affecting extracellular enzyme activities and microbial nutrient constraints. Our study revealed that the carbon and nitrogen limitation of soil microbes was induced by the variation in soil factors in a cold temperate mountain forest ecosystem. This finding provides important insights into the mechanism of microbial metabolic limitation in the face of climate change.

Positive and negative plant−plant interactions influence seedling establishment at both high and low elevations

Deciphering how plants interact with each other across environmental gradients is important to understand plant community assembly, as well as potential future plant responses to environmental change. Plant−plant interactions are expected to shift from predominantly negative (i.e. competition) to predominantly positive (i.e. facilitation) along gradients of environmental severity. However, most experiments examine the net effects of interactions by growing plants in either the presence or absence of neighbours, thereby neglecting the interplay of both negative and positive effects acting simultaneously within communities. To partially unravel these effects, we tested how the seedling establishment of 10 mountain grassland plants varied in the presence versus absence of plant communities at two sites along an elevation gradient. We created a third experimental treatment (using plastic plant mats to mimic surrounding vegetation) that retained the main hypothesised benefits of plant neighbours (microsite amelioration), while reducing a key negative effect (competition for soil resources). In contrast to our expectations, we found evidence for net positive effects of vegetation at the low elevation site, and net negative effects at the high elevation site. Interestingly, the negative effects of plant neighbours at high elevation were driven by high establishment rates of low elevation grasses in bare soil plots. At both sites, establishment rates were highest in artificial vegetation (after excluding two low elevation grasses at the high elevation site), indicating that positive effects of above-ground vegetation are partially offset by their negative effects. Our results demonstrate that both competition and facilitation act jointly to affect community structure across environmental gradients, while emphasising that competition can be strong also at higher elevations in temperate mountain regions. Consequently, plant−plant interactions are likely to influence the establishment of new, and persistence of resident, species in mountain plant communities as environments change.

Ecological responses of epigaeic beetle composition to a volcanic eruption across temperate mountains featuring a forest‐steppe transition

Abstract Monitoring changes in species composition near active volcanoes is important to identify environmental factors that maintain biological diversity after major disturbances. We investigated the taxonomic composition of epigaeic beetles' assemblages in five mountains in north‐western Patagonia (Argentina) in the aftermath of the 2011 Puyehue Cordón‐Caulle Volcanic Complex eruption. The associations of beetle composition with the thermal environment, vegetation structure and soil characteristics were analysed using 10 m × 10 m plots with nine pitfall traps each, established 100 m apart in altitude on each mountain in 2005, 2006 (pre‐eruption) and 2012, 2015 and 2016 (post‐eruption). We found significant differences in beetle composition between forests and high‐Andean steppes before and after the eruption. The beetle composition of forests and high‐Andean steppes differed due to higher plant cover and lower pH and herb richness in forests. Six months after the eruption, the herbs almost disappeared and forests showed high ash accumulation and lower temperature than the high‐Andean steppes. In the medium term, plant cover, temperature and soil conditions—but not ash accumulation—remained as important correlates of beetle composition. Before the eruption, forest assemblages showed higher beetle diversity and Leiodidae indicator species, but Curculionidae predominated post‐eruption. Tenebrionidae and Carabidae were high Andean steppes indicators. Post‐eruption, the beetle composition in high‐Andean steppes did not change significantly except for an increase in Tenebrionidae indicator species. We concluded that the conservation of landscape diversity and environmental gradients maintaining the differentiation between ecoregions is essential to protect epigaeic beetle composition and for species survival after volcanic disturbances.

Mapping subcanopy light regimes in temperate mountain forests from Airborne Laser Scanning, Sentinel-1 and Sentinel-2

Sunlight is the primary source of energy in forest ecosystems and subcanopy light regimes largely determine the establishment, growth and dispersal of plants and thus forest floor plant communities. Subcanopy light regimes are highly variable in both space and time, which makes monitoring them challenging. In this study, we assess the potential of Sentinel-1 and Sentinel-2 time series for predicting subcanopy light regimes in temperate mountain forests. We trained different random forest regression models predicting field-measured total site factor (TSF, proportion of potential direct and diffuse solar radiation reaching the forest floor, here defined as the transition zone between belowground and aboveground biomass) from a set of metrics derived from Sentinel-1 and Sentinel-2 time series. Model performance was benchmarked against a model based on structural metrics derived from Airborne Laser Scanning (ALS) data, serving as an empirical gold-standard in modelling subcanopy light regimes. We found that Sentinel-1 and Sentinel-2 time series performed nearly as good as the model based on high-resolution ALS data (R2/RMSE of 0.80/0.11 for Sentinel-1/2 compared to R2/RMSE of 0.90/0.08 for ALS). We furthermore tested the generalizability of the trained models to two new sites not used for training for which field data was available for validation. Prediction accuracy for the ALS model decreased substantially for the two independent test sites due to variable ALS data quality and acquisition date (ΔR2/ΔRMSE of 0.29/0.05 and 0.11/0.03 for both independent test sites). The prediction accuracy of the Sentinel-1/2 model, however, remained more stable (ΔR2/ΔRMSE of 0.13/0.02 and 0.13/0.04). We therefore conclude that a combination of Sentinel-1 and Sentinel-2 time series has the potential to map subcanopy light conditions spatially and temporally independent of the availability of high-resolution ALS data. This has important implications for the operational monitoring of forest ecosystems across large scales, which is often limited by the challenges related to acquiring airborne datasets.

A glacier in transition: Surface elevation change, ELA and geomorphic evolution of a very small glacier in the Dolomites (S-E Alps)

Small glaciers of temperate mountain regions are suffering significant reduction, with ice mass losses reaching unprecedented melt rates in the very last years. On the other hand, several glacial bodies experienced increasing debris inputs since the end of the Little Ice Age, transitioning from rather clean ice to debris-covered and, sometimes, to rock glaciers. Here we present the recent surface elevation change (2006–2022) of the Popera Alto glacier, a very small debris-covered glacier in the Sesto Dolomites (S-E European Alps), retrieved from a combination of airborne LiDAR and Structure from Motion surveys. We analyse the glacier evolution in terms of surface cover and geomorphic processes, reconstructing its palaeo-volume and -extent from geomorphological evidence. The environmental Equilibrium Line Altitude (envELA) based on climatic data is compared to the effective ELA (effELA), discussing the role of local topography in the evolution of small debris-covered glaciers. Popera Alto glacier lost 0.35 m w.e. yr−1 in the last 16 years, with its surface cover actively modified by geomorphic processes. Debris and local topography feedback allowed the resilience of the glacier, with marked difference between the current envELA of the area, 3480 m a.s.l., and the effELA of the glacier, 2550 m a.s.l. As such, Popera Alto glacier shows evidence of transitioning from a glacial to a periglacial landform.