Altitudinal Transect Research Articles

Flower surface is warmer in center than at edges in alpine plants: evidence from Qinghai-Tibetan Plateau

Abstract Although flower temperature plays an important role in plant reproduction, how it varies spatially on the flower surface is unclear, especially in alpine plants. To characterize spatial variation in flower surface temperature, we examined thermal images of flowers of 18 species along an altitudinal transect from 3200 to 4000 m on Lenglong Mountain on the north-eastern Qinghai-Tibetan Plateau. The surface temperature varied considerably within a flower or floral unit in all plants under sunlight, and was about 1 °C with a maximum of 11 °C higher in the center than at the edges. Solar radiation and flower shape significantly affected the temperature range and standard deviation and the ratio of flower center to edge temperature. The spatial variability of temperature increased with flower size. Flowers in the Asteraceae had higher surface temperatures, greater spatial variability of temperature, and consistently higher and more stable temperatures in the center than at the edge. The ratio of flower center to edge temperature increased with altitude in most species. Heat buildup at the flower center is likely to be widespread in alpine plants; further studies are needed to explore its ecological and evolutional roles.

Analysis of the Vigor of Pinus hartwegii Lindl. along an Altitudinal Gradient Using UAV Multispectral Images: Evidence of Forest Decline Possibly Associated with Climatic Change

Future climate forecasts predict major changes that will have negative impacts on the distribution, abundance, and dynamics of forest ecosystems. In Mexico, there is evidence of symptoms of massive forest decline; however, there is no consensus in terms of attributing these symptoms to climate change. This study aimed to provide evidence of forest decline possibly associated with climatic change in the highland pine (Pinus hartwegii Lindl.) populations of the Nevado de Toluca Flora and Fauna Protection Area. Using unmanned aerial vehicles (UAV) equipped with multispectral sensors, the study applied digital photogrammetry techniques, automated tree crown detection algorithms, and calculation of the normalized difference vegetation index (NDVI) and leaf chlorophyll index (LCI) to assess forest health across an altitudinal transect (from 3300 m to the timberline at 4040 m elevation). Climate analysis was conducted with TerraClimate data using mean annual temperature (MAT), April temperature, and Palmer Drought Severity Index (PDSI) from the studied altitudinal transect and its xeric limit. We found that lower altitude populations had significantly higher stress levels, indicating forest decline phenomena, while intermediate altitude populations showed greater vigor of the detected trees. Statistically significant differences in the NDVI and LCI values along the altitudinal gradient provided evidence of forest decline in terms of forest vigor and productivity, with the greatest disturbance found at the lower altitude of the examined forest species. The analysis of the climatic data revealed an increase in April temperature +1.4 °C of the xeric limit of the transect (low altitude) when comparing the reference period, 1961–1990 (mean: 12.17 °C), with the decade prior to our study (2011–2020; mean: 13.57 °C). This would be equivalent to an upward shift in elevation of 280 m of the xeric limit. In addition, the PDSI analysis revealed that droughts are becoming increasingly intense at a rate of 0.06 PDSI units per decade, with greater intensity in the last five years. These findings highlight the negative impacts of climate change on forest ecosystems and the urgent need for alternative forest management and conservation practices to increase resilience and adaptation in the temperate forests of Mexico. This study sets a precedent for further research to improve our understanding of the impacts of climate change on forest ecosystems and the development of sustainable management practices.

Establishing the Position and Drivers of the Eastern Andean Treeline with Automated Transect Sampling

The eastern Andean treeline (EATL) is the world’s longest altitudinal ecotone and plays an important role in biodiversity conservation in the context of land use/cover and climate change. The purpose of this study was to assess to what extent the position of the tropical EATL (9°N–18°S) is in near-equilibrium with the climate, which determines its potential to adapt to climate change. On a continental scale, we have used land cover maps (MODIS MCD12) and elevation data (SRTM) to make the first-order assessment of the EATL position and continuity. For the assessment on a local scale and to address the three-dimensional nature of environmental change in mountainous environments, a novel method of automated delineation and assessment of altitudinal transects was devised and applied to Landsat-based forest maps (GLAD) and fine-resolution climatology (CHELSA). The emergence of a consistent longitudinal gradient of the treeline elevation over half of the EATL extent, which increases towards the equator by ~30 m and ~60 m per geographic degree from the south and north, respectively, serves as a first-order validation of the approach, while the local transects reveal a more nuanced aspect-dependent pattern. We conclude that the applied dual-scale approach with automated mass transect sampling allows for an improved understanding of treeline dynamics.

Representation of the Hyrcanian forest (northern Iran) in modern pollen rain revealed by palynological and DNA-metabarcoding data

We studied the modern pollen rain in two different landscapes from Hyrcanian lowland forests up to the slopes of the Alborz Mountains in Gilan province for the first time. Pollen traps were installed for one year and moss samples were collected along two altitudinal transects from 100 to 1800 m and from 100 to 2300 m elevations. The results of pollen counting and environmental DNA barcoding (metabarcoding) of the collected pollen and moss samples were compared from 32 locations. In total, 81 vascular plant species from 36 families were identified by metabarcoding, and 68 taxa belonging to 39 families were identified by pollen counting. The pollen counting results reflect mainly wind-pollinated families, such as Betulaceae and Fagaceae while results from metabarcoding of the rbcL and ITS2 loci were more in line with the vegetation around the pollen traps and the moss samples. Furthermore, this study showed that the rbcL region is able to identify more taxa than the ITS2 region, while applying both markers provides higher confidence. Also using both metabarcoding and pollen data provides a better local and regional vegetation representation.

Altitude patterns of seed C, N, and P concentrations and their stoichiometry in an alpine meadow on the eastern Tibetan Plateau

Understanding the altitudinal patterns of plant stoichiometry in seeds is critical for characterizing important germination and dormancy strategies, soil seed bank composition, seed predation probability, efficiency of seed dispersal and seedling performance, and to predict how biodiversity might be influenced by climate change. However, our understanding of the altitudinal patterns of seed stoichiometry is extremely limited. In this study, we measured the concentrations of carbon (C), nitrogen (N) and phosphorus (P) in the seeds of 253 herbaceous species along an altitudinal transect (2,000–4,200 m) on the eastern Tibetan Plateau, China, and further to characterize seed C:N:P stoichiometry. The geometric means of C, N, and P concentrations were 569.75 mg/g, 34.76 mg/g, and 5.03 mg/g, respectively. The C:N, C:P, and N:P ratios were 16.39, 113.31, and 6.91, respectively. The seed C, N, and P concentrations and C:N:P ratios varied widely among major plant groups and showed significant altitudinal trends. In general, C, N, and P concentrations increased, whereas seed C:N:P ratios decreased with elevation. These results inform our understanding of the altitudinal patterns of seed stoichiometry and how to model ecosystem nutrient cycling.

Predicting Leaf Phenology in Forest Tree Species Using UAVs and Satellite Images: A Case Study for European Beech (Fagus sylvatica L.)

Understanding forest tree phenology is essential for assessing forest ecosystem responses to environmental changes. Observations of phenology using remote sensing devices, such as satellite imagery and Unmanned Aerial Vehicles (UAVs), along with machine learning, are promising techniques. They offer fast, accurate, and unbiased results linked to ground data to enable us to understand ecosystem processes. Here, we focused on European beech, one of Europe’s most common forest tree species, along an altitudinal transect in the Carpathian Mountains. We performed ground observations of leaf phenology and collected aerial images using UAVs and satellite-based biophysical vegetation parameters. We studied the time series correlations between ground data and remote sensing observations (GLI r = 0.86 and FCover r = 0.91) and identified the most suitable vegetation indices (VIs). We trained linear and non-linear (random forest) models to predict the leaf phenology as a percentage of leaf cover on test datasets; the models had reasonable accuracy, RMSE percentages of 8% for individual trees, using UAV, and 12% as an average site value, using the Copernicus biophysical parameters. Our results suggest that the UAVs and satellite images can provide reliable data regarding leaf phenology in the European beech.

Forest stand-by-environment interaction invalidates the use of space-for-time substitution for site index modeling under climate change

Quantification and prediction of forest site productivity potential under climate changes are core issues of growth and yield modelling and crucial for the effective management of forest stands. Climatic factors typically enter these models as long-term baseline data of mean air temperature and sum of precipitation. Such models frequently are parameterized using spatially distributed data, an approach that can be considered as indirect space-for-time substitution (SFTS), which is based on the assumption that the growth response across spatial environmental gradients is equivalent to the dynamic growth response in time when site factors shift in situ due to environmental changes over time. In site index modelling this assumption has never been thoroughly tested. We applied procedures to test the validity of the SFTS approach using altitudinal transect analysis of data from long-term experimental plots with Norway spruce (Picea abies) in southwest Germany. The following procedures were applied 1. Partitioning of spatial and temporal variance components of site index and air temperature; 2. Test of the equivalence of spatial and temporal variation in models predicting site index from air temperature; 3. Bias analysis of the SFTS- and the altitudinal range-specific individual models. The results show that the response of site index to changes in growing season air temperature as estimated by the SFTS-based approach is significantly different from the observed temporal dynamics within the plots. The estimated sensitivity of site index to changes in growing season air temperature is significantly larger in the SFTS-model. Bias trends increase with increasing air temperature in all altitudinal ranges. We found significant effects of stand-by-environment interaction on site index responses to changing growing season air temperature. Possible reasons for the found differences are discussed. Furthermore, based on an independent data set from the German National Forestry Inventory (NFI), a SFTS-based climate-sensitive site index model was compared to a state-space modelling approach (SSM) which considers the dynamics of environmental changes over time. The results show that the SSM is statistically superior to the SFTS approach, corroborating the findings of the altitudinal transect analysis. Finally, future site index dynamics of Norway spruce were simulated on the basis of climate change scenarios using the SSM approach. We recommend for all climate sensitive forest growth and yield models based on spatially and temporally distributed data to properly account for within- and between-group effects to avoid erroneous model predictions under climate change.

Morphological and molecular results from a geographical transect focusing on Quercus pubescens/Q. virgiliana ecological-altitudinal vicariance in peninsular Italy

Quercus pubescens and Q. virgiliana are the most cited taxa in the Italian deciduous oak forests floristic and phytosociological literature. According to some authors, Q. pubescens is typical of inland areas and higher altitudes whereas Q. virgiliana restricted to the coastal plain and the hilly belt. Seven pubescent oak populations distributed along an altitudinal transect in central Italy have been analysed from a coenological, morphological and molecular point of view. The vegetation sampling was carried out using the phytosociological approach. Morphological variation of tree individuals was analysed using 14 leaf traits, while leaf shape variation was investigated using the Procrustes ANOVA. Genetic analyses were carried out through twelve EST-SSRs markers. Results: only the leaf pubescence exhibited discriminating power among all the leaf morphological traits considered. Very low differences in the leaf-shape emerged from geometric morphometric analysis. Genetic analyses did not evidence statistically significant clusters. Bayesian analyses including data from genetically pure populations of Q. pubescens, Q. petraea and Q. frainetto assigned all the seven populations investigated to Q. pubescens. Neither the morphological nor the genetic results allowed to identify specimens attributable to Q. pubescens or Q. virgiliana nor to highlight a possible ecological-altitudinal vicariance between these two species.

Influence of landscape heterogeneity on entomological and parasitological indices of malaria in Kisumu, Western Kenya

BackgroundIdentification and characterization of larval habitats, documentation of Anopheles spp. composition and abundance, and Plasmodium spp. infection burden are critical components of integrated vector management. The present study aimed to investigate the effect of landscape heterogeneity on entomological and parasitological indices of malaria in western Kenya.MethodsA cross-sectional entomological and parasitological survey was conducted along an altitudinal transect in three eco-epidemiological zones: lakeshore along the lakeside, hillside, and highland plateau during the wet and dry seasons in 2020 in Kisumu County, Kenya. Larval habitats for Anopheles mosquitoes were identified and characterized. Adult mosquitoes were sampled using pyrethrum spray catches (PSC). Finger prick blood samples were taken from residents and examined for malaria parasites by real-time PCR (RT-PCR).ResultsIncreased risk of Plasmodium falciparum infection was associated with residency in the lakeshore zone, school-age children, rainy season, and no ITNs (χ2 = 41.201, df = 9, P < 0.0001). Similarly, lakeshore zone and the rainy season significantly increased Anopheles spp. abundance. However, house structures such as wall type and whether the eave spaces were closed or open, as well as the use of ITNs, did not affect Anopheles spp. densities in the homes (χ2 = 38.695, df = 7, P < 0.0001). Anopheles funestus (41.8%) and An. arabiensis (29.1%) were the most abundant vectors in all zones. Sporozoite prevalence was 5.6% and 3.2% in the two species respectively. The lakeshore zone had the highest sporozoite prevalence (4.4%, 7/160) and inoculation rates (135.2 infective bites/person/year). High larval densities were significantly associated with lakeshore zone and hillside zones, animal hoof prints and tire truck larval habitats, wetland and pasture land, and the wet season. The larval habitat types differed significantly across the landscape zones and seasonality (χ2 = 1453.044, df = 298, P < 0.0001).ConclusionThe empirical evidence on the impact of landscape heterogeneity and seasonality on vector densities, parasite transmission, and Plasmodium infections in humans emphasizes the importance of tailoring specific adaptive environmental management interventions to specific landscape attributes to have a significant impact on transmission reduction.Graphical abstract

Variación fitoquímica entre procedencias de oyamel (Abies religiosa [Kunth] Schltdl. &amp; Cham.) en un gradiente altitudinal

Introduction: A species’ populations differ across its distribution due to selection pressure from the climate gradient. Objective: To describe the phytochemical variation among 14 tree provenances in an altitudinal gradient of Abies religiosa (Kunth) Schltdl. &amp; Cham. to determine if there are associations of chemical profiles among populations, expressed under a single environment. Materials and methods: Seeds were collected from 165 trees from an altitudinal transect from 2 850 to 3 540 m in Cerro San Andrés, Municipio Libre de Hidalgo, Michoacán, Mexico. The plant was grown in a common garden trial; at 28 months, mature needles were collected per tree and analyzed by gas-mass chromatography. Data were analyzed with diversity indices, ANOVA and multivariate analysis (principal components, correspondences and cluster). Results and discussion: Thirty-two compounds were identified, most of them terpenes. The populations showed differences in presence/absence of terpenes and in their concentration; above 3 350 m, diversity was lower, but with higher concentration. Three altitude groups were found based on the chemical profile of the populations: low = 2 850 to 3 300 m and 3 400 m; moderate = 3 350, 3 450 and 3 500 m; and high= 3 540 m. Conclusions: The diversity and concentration of terpenes in A. religiosa varied depending on the altitude of populations. There are three chemical profiles that should be considered in the implementation of germplasm collection programs for reforestation and restoration

Repeated genetic adaptation to altitude in two tropical butterflies

Repeated evolution can provide insight into the mechanisms that facilitate adaptation to novel or changing environments. Here we study adaptation to altitude in two tropical butterflies, Heliconius erato and H. melpomene, which have repeatedly and independently adapted to montane habitats on either side of the Andes. We sequenced 518 whole genomes from altitudinal transects and found many regions differentiated between highland (~ 1200 m) and lowland (~ 200 m) populations. We show repeated genetic differentiation across replicate populations within species, including allopatric comparisons. In contrast, there is little molecular parallelism between the two species. By sampling five close relatives, we find that a large proportion of divergent regions identified within species have arisen from standing variation and putative adaptive introgression from high-altitude specialist species. Taken together our study supports a role for both standing genetic variation and gene flow from independently adapted species in promoting parallel local adaptation to the environment.

Hay meadows' overriding effect shapes ground beetle functional diversity in mountainous landscapes

AbstractMountain regions are hotspots of biodiversity, and are particularly sensitive to human activities and global changes. Characterizing biodiversity using trait‐based approaches may improve the understanding of the evolutionary and mechanistic basis of ecological patterns in species distribution. The investigation of trait–environment relationships, however, is challenging, especially when a hierarchical sampling design is used, as this may lead to misidentification of associations. Here, we investigate how functional traits in ground beetles (Coleoptera: Carabidae), a taxon often used as a bioindicator of climate and environmental changes, vary with environmental features in a mountainous landscape. The study was conducted in the Stelvio National Park (Central Italian Alps), collecting individuals with pitfall traps deployed within plots (small spatial scale), located along altitudinal transects (large spatial scale). To investigate the trait–environment association, we used double constrained correspondence analysis, which permits the selection of important traits and environmental variables while accounting for the hierarchical structure of the sampling design. The trait–environment association was largely one‐dimensional, with hay meadow acting as main environmental driver, negatively related to brachypterous wing‐form (indicator of poor dispersal ability) and, to a lesser extent, to specialized diet and (only for the large scale) body length. Secondarily, these traits were related negatively to soil pH and, for the larger spatial scale, positively to canopy cover and elevation. Double constrained correspondence analysis with specialized permutation schemes for statistical testing was effective and robust to analyze the data of the hierarchical sampling.

Modern pollen–vegetation relationships along an altitudinal transect in the Western Higher Himalaya, India: Palaeoclimatic and anthropogenic implications

Palynology is one of the most reliable tools for the reconstruction of past vegetation and climate and modern pollen analogues are important for the calibration of fossil pollen assemblages. The present study analyses the pollen–vegetation relationships along a steep altitudinal gradient (2700–3680 m), in the western Higher Himalayan region. On the basis of altitude, three vegetation zones were demarcated: Zone I (2700–3100 m) is composed of mixed-temperate forest vegetation, dominated by Quercus semecarpifolia and Rhododendron arboreum; Zone II (3100–3250 m) is marked by sub-alpine forest vegetation, characterised by R. campanulatum and R. barbatum, along with Abies spectabilis and Q. semecarpifolia; Zone III (3250–3680 m) is above the tree-line (3250 m) and represented by alpine-scrub and meadows. Thirty-five surface soil samples (twenty, seven and eight from each zone, respectively) were analysed along the altitudinal transect to decode the representation of the extant vegetation in the pollen-rain. The pollen–vegetation relationship is non-linear due to the over-representation of extra-local Pinus pollen in each zone. Nonetheless, the modern pollen assemblages show a general correlation with the local broad-leaved taxa and the herbaceous elements; with the exception of Rhododendron pollen, which is under-represented. Among the non-pollen palynomorphs (NPPs), the presence of coprophilous fungal spores is compatible with the grazing activities in the area. Multivariate statistical analyses performed on the surface pollen data indicate that the dataset can efficiently distinguish the different vegetation zones across the altitudinal gradient. This work provides the modern analogues for pollen-based palaeoclimatic reconstructions for the Western-Higher Himalayan region, and would also help to decipher the inception and intensification of anthropogenic activities in the region.

The elevation gradient of small mammals richness and abundance in the dry Andes of northwestern Argentina

In this research we explore elevation gradient of small mammal diversity on the arid slopes of the Andes in northwestern Argentina. We evaluated the influence of climatic and environmental factors on species richness and abundance across two altitudinal transects between 2700 and 4700 m. We used canonical correspondence analysis, multiple regressions (GLM's), and variation partitioning analysis to evaluate the primary productivity, environmental heterogeneity, and climate as drivers of species diversity. The general trend indicates a greater diversity towards high elevation with an abrupt decrease towards the summit. The most remarkable pattern was the coincident distribution of the maximum values for both, abundance and richness at the same altitude (3700 m). The species richness showed a flattened distribution with the maximum values between 3200 and 3700 m and a small peak at 4200 m. We found that the joint effects of environmental heterogeneity with productivity explained most of the variation for richness and abundance (86.5%, 63.2% respectively). These results highlight the complexity of the mountain environments in desert areas while emphasizing the importance of these habitats for the maintenance of biological diversity. Our results constitute an important tool for the conservation of small mammals diversity in these mountain arid environments.

Permafrost, thermal conditions and vegetation patterns since the mid-20th century: A remote sensing approach applied to Jotunheimen, Norway

Northern high-alpine regions are currently experiencing rapid warming, which often results in the degradation of sub-surface permafrost and the upslope advancement of vegetation. The present study combines remotely sensed MODIS Land Surface Temperatures (LSTs) and the Normalised Difference Vegetation Index (NDVI) with observed air temperatures to model the thermal and vegetational dynamics in NE Jotunheimen (Norway) for the period 1957–2019. An altitudinal transect on the north-facing slope of Galdhøpiggen was used for ground truthing. Results indicate a substantial warming trend since the late 1950s, accompanied by increased NDVI. The spatial and temporal patterns of observed change were not uniform. Winter surface temperatures increased most rapidly, by 2.4–2.8°C at mid- and low altitudes (600–1500 m a.s.l.). The highest increases in NDVI (by ∼0.1) were detected during the growing season (April–September) and over the mid-range altitudes (1050–1500 m a.s.l.), that is, above the tree line on Galdhøpiggen. We attribute this to increased shrubification at these altitudes. Our results confirm that the surface temperatures near the previously estimated lower altitudinal limit of permafrost (∼1450 m a.s.l.) have continued to increase during the past decade, likely facilitating further permafrost degradation. Finally, we demonstrate that mapping remotely sensed mean growing season LSTs below 0°C can be used to identify areas suitable for continuous sub-surface permafrost, and mean June–September LSTs above 7°C can detect areas suitable for tree ( Betula pubescens) growth in NE Jotunheimen.

FACTORS AFFECTING DISTRIBUTION AND HABITAT ASSOCIATION OF RED PANDA IN BHOJPUR DISTRICT, NEPAL

Status and distribution of red panda outside the protected area are poorly explored in Nepal despite of occupying the large share of potential red panda habitat. This study attempted to identify the factors affecting distribution and habitat association of red panda in Bhojpur district, Nepal. Bhalukhola Forest Patch, Kholakharka Forest Patch and Silichung Forest Patches were selected as intensive study sites. Altitudinal line intercepts method and sign surveys were applied to determine the distribution of red panda along different elevations. Quadrate method was implemented to explore the habitat association of the species. Twenty-four altitudinal transects each of 1,000 m on every 100 m altitude were surveyed following contour lines from the elevation of 2,400 m to 3,550 m. All the data were analysed by using Microsoft Excel 2016, ArcGIS 10.4 and Past 3.26 Software. Generalized Linear Model (GLM) was used to assess the influence of elevation and habitat parameters (predictor variables) with presence of red panda i.e. pellet frequency (response variable). Red panda was confirmed in all the surveyed forest patches between 2,700 m to 3,000 m altitude. In addition, 44 tree species were documented from red panda sign plots, out of which most common was Pinus roxburghii (77.39), Rhododendron arboretum (29.35), Tsuga dumosa (28.51) and Rhododendron grande (22.06). Based on the habitat association analysis, GLM revealed that elevation (R2=0.23), bamboo canopy cover (P˂ 0.01), tree canopy cover (P˂ 0.01), bamboo density (P˂ 0.01), and distance to settlement (P˂ 0.01) were positively associated with red panda presence. Likewise, tree height (P˂ 0.01), distance to water source (P˂ 0.01) and DBH of tree (P˂ 0.01) were negatively associated. The most preferred aspect was found to be North-West (31%) with the average slope of 30o. Tree branches were mostly used substrate by the red panda for defecation (56.36%). Mostly used tree species for defecation was Hymenodictylon excelsum (26%). This study has provided vivid information about the presence of red panda in one of the potential regions outside protected area. Further research should be conducted to find out distribution pattern, abundance and association of red panda with different habitat characteristics throughout the Bhojpur district.

Phenological response patterns of forest communities to annual weather variability at long-term ecological monitoring sites in Western Himalaya

This paper presents the periodicity of phenophases in 28 tree species (142 individuals), 58 shrub, and 72 herb species' populations for 23 months (during 2018–2020) vis-a-vis weather variability in four semi-deciduous and evergreen forests along an altitudinal transect (680–1860 m asl) in long-term ecological monitoring (LTEM) sites in Western Himalaya. Across these forests, atmospheric temperature, relative humidity, and annual rainfall declined significantly with increasing elevation. The autumn to winter period (October-February) of 2019 was characterized by higher temperature (0.49 °C), rainfall (48.5 mm), and relative humidity (9%) in comparison to 2018. Vegetative bud-break, leafing and leaf drop occurred predominantly in the spring season (March-April) followed by flowering and fruiting through summer until the onset of the rainy season. All the phenophases occurred in 3–4 episodes of varying magnitudes year-round, except for a few months during the rainy season. The year 2019 was characterized by earliness in bud-break and leafing by over 2 weeks as compared to 2018. This may be attributed to the greater elevation-dependant warming as reflected by the shallow mean annual temperature lapse rate (−0.36 ± 0.2 °C/100 m) observed for the study area than the commonly used value (−0.65 °C/100 m). In the warmer winter of 2019–20 owing to greater temperature and rainfall, the leaf senescence delayed resulting in a lower magnitude of leaf drop by ∼25% than that recorded in winter 2018–19. This shift may have certain structural and functional implications in these forests which need to be investigated for a longer period establishing LTEM sites to understand the impact of climate change.

Altitudinal variation in body size and resistance to stress in Drosophila melanogaster and D. simulans (Diptera: Drosophilidae) in southern Turkey

Tolerance of cold and heat and body size are traits that are important in thermal selection. Latitudinal and altitudinal transects include environments that gradually change in temperature. However, while there are studies on the effects on body size and cold tolerance in natural populations sampled mostly along latitudinal transects, there are few such studies along altitudinal transects. Resistance to starvation and desiccation, which are also thought to be affected by temperature, are the focus of studies on clines. In this study, we measured the variation in tolerance of cold (chill coma recovery time), body size, resistance to starvation and desiccation in isofemale lines of Drosophila melanogaster and D. simulans that originated from four locations (50 m - 1500 m) along an altitudinal transect in the southern part of Turkey. This revealed clines in the tolerance of cold and body size along the altitudinal transect with some degree of difference between these two species, whereas there were no clines in resistance to starvation and desiccation. This study revealed some differences and similarities between the sibling species D. melanogaster and D. simulans.

Low abundance but high land snail diversity in montane rainforest on the western slope of the Andes in Ecuador

ABSTRACT We investigated the land snail fauna along an altitudinal transect in the Los Cedros Biological Reserve on the western slope of the Andes in Ecuador. A total of 510 individuals were collected in 40 plots between c. 1,100 and 2,000 m a.s.l. and assigned to 80 land snail species. The mean iChao1 estimate of species richness was with 109 species (with a 95% confidence interval from 97 to 130 species) much higher because many species were represented only by one or two specimens. On the basis of available data, Los Cedros is the most species-rich locality for land snails in South America. Almost half of the land snail species and 75% of the sampled individuals belong to the carnivorous Scolodontidae, most of which are likely to be new to science. In comparison with an Amazonian rainforest, the proportion of tropical groups such as the Helicinoidea or the Achatinidae is reduced, whereas the proportions of the Labyrinthidae and Charopidae are higher at higher elevations in the Andes than at the margin of the Amazonas basin. Beckianum beckianum, Hirtudiscus sp., Pupisoma mediamericanum, Guppya gundlachii, Eobania vermiculata and Thysanophora plagioptycha are new records for Ecuador. The finding of the Mediterranean Eobania vermiculata in cultivated areas adjacent to the reserve is the first record of this species in South America.

Stand Biomass at Treeline Ecotone in Russian Subarctic Mountains Is Primarily Related to Species Composition but Its Dynamics Driven by Improvement of Climatic Conditions

Climate change effects are strongest in forest ecosystems at the limit of their distributions. Despite the evidence that treelines have shifted upwards by hundreds of meters, knowledge of the associated changes in the stand biomass is limited. In this study, stand biomass and changes to it during the last centuries were estimated along 20 altitudinal transects reaching from the historical (located in the 1950s–1960s) closed forest line up to the current treelines on mountain slopes of three subarctic regions of Russia (Kola Peninsula, Polar Urals, and Putorana Plateau) along a 2200 km long longitudinal gradient. The estimates were based on allometric measurements of 139 trees of five species (Betula pubescens Ehrh. ssp. tortuosa, Pinus sylvestris L., Picea abies Ledeb. ssp. obovata, Larix sibirica Ledeb., and Larix gmelinii Rupr.), stand structure assessments, and the demographic patterns of 9300 trees. During the 20th century, the growth and establishment of trees at the forest–mountain tundra transition (340–500 m width) increased exponentially. Since 1910 forest expansion and densification led to an accumulation of 621–748 tons of aboveground stand biomass per km of treeline length. The accumulation was two times higher below than above the contemporary closed forest line. Data analysis of weather stations showed that the 20th century’s climate had changed in a similar manner in the three study regions, namely vegetation periods became longer (8–10 days) and warmer (0.6–0.9 °C) and more snow fell in the cold period (+10–30%). Our results indicate that regional patterns in stand biomass at the treeline ecotone are primarily related to tree species composition as determined by macroclimatic conditions (e.g., continentality, sunshine hours), snowpack depth, and growing season duration. However, the stand biomass accumulation was driven by increases of early summer temperatures and early winter precipitation during the last century.