Altitudinal gradients in Magellanic sub-Antarctic lagoons: the effect of elevation on freshwater macroinvertebrate diversity and distribution

Species richness patterns along altitudinal gradients are well-documented ecological phenomena, yet very little data are available on how environmental filtering processes influence the composition and traits of butterfly assemblages at high altitudes. We have studied the diversity patterns of butterfly species at 34 sites along an altitudinal gradient ranging from 600 to 2,000 m a.s.l. in the National Park Berchtesgaden (Germany) and analysed traits of butterfly assemblages associated with dispersal capacity, reproductive strategies and developmental time from lowlands to highlands, including phylogenetic analyses. We found a linear decline in butterfly species richness along the altitudinal gradient, but the phylogenetic relatedness of the butterfly assemblages did not increase with altitude. Compared to butterfly assemblages at lower altitudes, those at higher altitudes were composed of species with larger wings (on average 9%) which laid an average of 68% more eggs. In contrast, egg maturation time in butterfly assemblages decreased by about 22% along the altitudinal gradient. Further, butterfly assemblages at higher altitudes were increasingly dominated by less widespread species. Based on our abundance data, but not on data in the literature, population density increased with altitude, suggesting a reversed density-distribution relationship, with higher population densities of habitat specialists in harsh environments. In conclusion, our data provide evidence for significant shifts in the composition of butterfly assemblages and for the dominance of different traits along the altitudinal gradient. In our study, these changes were mainly driven by environmental factors, whereas phylogenetic filtering played a minor role along the studied altitudinal range.

Knowledge about the phylogeny and ecology of communities along environmental gradients helps to disentangle the role of competition-driven processes and environmental filtering for community assembly. In this study, we evaluated patterns in species richness, phylogenetic structure and life-history traits of bee communities along altitudinal gradients in the Alps, Germany. We found a linear decline in species richness and abundance but increasing phylogenetic clustering in communities with increasing altitude. The proportion of social- and ground-nesting species, as well as mean body size and altitudinal range of bee communities, increased with increasing altitude, whereas the mean geographical distribution decreased. Our results suggest that community assembly at high altitudes is dominated by environmental filtering effects, whereas the relative importance of competition increases at low altitudes. We conclude that inherent phylogenetic and ecological species attributes at high altitudes pose a threat for less competitive alpine specialists with ongoing climate change.

Species composition, cover, diversity, and temporal dynamics of the three main plant communities in the channelized Kissimmee River floodplain were evaluated to provide a baseline for tracking the success of an ongoing restoration project. Much of the drained floodplain supports an upland herbaceous community with cover dominated by the planted pasture grasses Paspalum notatum and Axonopus fissifolius. Mesophytic woody communities are comprised primarily of Myrica cerifera, Baccharis halimifolia, Ludwigia peruviana, and understory ferns, while Sagittaria lancifolia, Pontederia cordata, and Panicum hemitomon are dominant species in remnant wetland communities. Community composition and the associated gradient of weighted averages of wetland indicator species reflect prevailing hydroperiods and land uses on the drained floodplain. Managed hydrologic regimes have promoted temporal stability, with seasonal variability of plant community characteristics limited to a decline in live plant cover and species richness during winter months. Lower live vegetation cover during winter resulted from senescence of dominant herbaceous species, while the winter decline in species richness was due primarily to sampling error resulting from seasonal phenology of taxonomic characteristics and obscured growth of rare or diminutive species. The limited variability of plant community characteristics in the channelized floodplain reduces the potential for confounding uncertainty in evaluating successful restoration. Results indicate that functional assessment of plant community characteristics in this subtropical floodplain is most accurately measured in spring and summer.

In this study we investigate the impact of nitrogen (N) deposition on the diversity of three different vegetation functional groups – forbs, grasses and mosses – using a field survey of acid grasslands across Great Britain. Our aim is to identify the vegetation types that are most vulnerable to enhanced N deposition, and to shed light on the mechanisms that may be driving N‐initiated species changes in the UK. Sixty‐eight randomly selected grasslands belonging to the UK National Vegetation Classification group U4 (Festuca ovina–Agrostis capillaris–Galium saxatile grassland) were studied along a gradient of atmospheric N deposition ranging from 6 to 36 kg N ha−1 yr−1. At each site, vegetation was surveyed and samples were taken from the topsoil and subsoil. Aboveground plant material was collected from three species: a forb, grass and moss. Both the species richness and cover of forbs declined strongly with increasing N deposition, from greater than eight species/20% cover per m2 quadrat at low levels of N to fewer than two species/5% cover at the highest N deposition levels. Grasses showed a weak but significant decline in species richness, and a trend toward increasing cover with increasing N input. Mosses showed no trends in either species richness or cover. Most of the decline in plant species richness could be accounted for by the level of ammonium deposition. Soil KCl‐extractable ammonium concentration showed a significant positive correlation with N input, but there was no relationship between N deposition and extractable nitrate. In the soil O/A horizon, there was no relationship between N deposition and %N, and only a very weak positive relationship between the level of N deposition and the C : N ratio. Finally, in the vegetation, there was no relationship between N deposition and either shoot tissue N concentration or N : P ratio for any of the three reference species. Combining our regional survey with the results of published N‐addition experiments provides compelling evidence that there has been a significant decline in the species richness and cover of forbs across Great Britain, and that the primary cause is competition due to an increase in the cover of grasses in response to enhanced deposition of reactive N, primarily NH4+.

It is generally accepted that current and forecast rates of climate change will have a substantial effect on terrestrial biota, especially at high southern latitudes. This thesis investigated trends in 50 years of climate data (1948-1998) and the microclimate at sites along an altitudinal gradient on subantarctic Macquarie Island. Seasonal patterns in the foliar morphology, production, photosynthesis and reproduction of six widely distributed and ecologically important vascular plant species were also examined at these sites. The six species investigated were Poa foliosa (Hook f.) Hook. F. (Poaceae), Agrostis magellanica Lam. (Poaceae), Luzula crinita Hook. F. (Juncaceae), Acaena magellanica (Lam.) Vahl (Rosaceae), Acaena minor (Hook. F.) Allan, and Stilbocarpa polaris (Hombr. & Jacquinot ex Hook. f. A. Gray (Araliaceae). The potential impact of climate change on the productivity and reproduction of each species was assessed based on an altitudinal temperature gradient analogy. This analogy proposes that low altitude sites (i.e. comparatively warm) are potential forecasts of high altitude sites (i.e. comparatively cool) under a climate-warming scenario. Climate change trends for meteorological parameters and biologically relevant climatic indices were investigated using univariate ARIMA time series analysis and forecasts were made to the year 2030. These analyses forecast continued increases in air temperature, wind speed, precipitation and evapotranspiration and decreases in air moisture content and sunshine. The microclimate of sites at 10, 200, 365 and 370 metres above sea level (masl) along an East facing coastal slope was recorded for ca. 12 months (September 1996 to October 1997) using automatic weather stations. With increasing site altitude, the climate became cooler, windier and wetter, consistent with the proposed climate change analogy and forecast patterns of climate change. Foliar morphology and productivity estimates decreased with increasing site altitude for most species, similar to that documented by other studies conducted on Macquarie Island, other subantarctic islands and elsewhere in high latitude and alpine ecosystems. It appears that the productivity gradient that exists on the coastal slopes of Macquarie Island could be the largest documented over such a short horizontal distance and altitudinal range in the world. At low altitude sites, dry matter production was high and comparable to estimates for tropical rainforests for some species (ca. 39 t/ha/yr). At high altitudes, productivity estimates were low and comparable to estimates for tropical and polar deserts (ca. 1 t/ha/yr). The acquisition, utilisation and cycling of nutrients by most species appeared to be pulsed. Patterns of photosynthetic capacity were typical of plants acclimatised to low to medium light levels and there were strong correlations between measurements made using fluorescence and gas exchange techniques that indicated photosynthesis was limited by light-induced photoinhibition and temperature.There was a delay in reproductive development with increasing site altitude and breeding systems of high and low altitude populations for most species were separated temporally. All species showed signs of reduced reproductive output with increasing site altitude. Agrostis magellanica and L. crinita were the only species that displayed significant ecotypic differentiation in common garden experiments. Other species showed a high level of phenotypic variability between populations, and weak indications of ecotypic differentiation.Deterministic models that predicted production from several environmental variables were developed and forecasts made to 2030 for sites along an altitudinal gradient, integrating climate change trends, climate variation over the altitudinal gradient and patterns of production. Models suggest populations at high altitudes are at a greater risk of change relative to low altitude populations and that each species will respond differently. This implies species composition and abundance in some communities may also change. Model outputs support some observations of long-term vegetation change on the island, which have previously been related to a reduction in rabbit grazing. Deterministic reproductive development models from reproductive seasons differing climatically showed reproductive performance in most species was related to climatic conditions in the season prior to reproduction. This suggests that with the ameliorating conditions forecast with climate change, rates of reproductive development will increase, and may result in decreased temporal separation in reproduction and increased gene flow between populations separated by altitude. The likely implication of this is reduced ecotypic differentiation, which could be important in maintaining genetic diversity in some species on Macquarie Island. Other potential impacts of climate change, applications of findings to management, and suggestions for further research are also discussed.

The present study investigates the altitudinal variation in floristic composition and phytosociological attributes of temperate forests in the Langate Forest Division of the Kashmir Himalayas, with a particular focus on habitats of Arnebia benthamii, a critically rare and medicinally important alpine species. The study area, located between 1590 and 4308 m a.m.s.l., is characterized by a temperate continental climate and diverse vegetation types along its altitudinal gradient. Vegetation sampling was conducted across three distinct elevations—3000 m, 3300 m, and 3600 m—using the quadrat method for trees (10×10 m), shrubs (5×5 m), and herbs (1×1 m). Species frequency, density, and Importance Value Index (IVI) were calculated to assess community structure and species dominance. A cumulative total of 6 tree, 10 shrub, and 52 herbaceous species were recorded. Species composition and structure showed marked altitudinal variation. At 3000 m, Acer caesium, Viburnum grandiflorum, and Sibbaldia cuneata were dominant among trees, shrubs, and herbs respectively. At 3300 m, dominance shifted to Betula utilis, Salix denticulata, and again Sibbaldia cuneata among respective layers. At the highest altitude (3600 m), Betula utilis, Berberis jaeschkeana, and Bergenia ciliata showed maximum IVI among trees, shrubs, and herbs respectively. Notably, Arnebia benthamii was restricted solely to the 3600 m elevation, underscoring its narrow ecological amplitude and highlighting its vulnerability to climatic and ecological shifts. A gradual decline in species richness and density was observed with increasing altitude, likely due to lower temperatures, reduced soil fertility, and shorter growing seasons. High-altitude medicinal species like Aconitum heterophyllum and Saussurea costus exhibited low IVI values, raising serious conservation concerns under projected climate change scenarios.

Davidia involucrata has an ancient origin, representing a remnant from the paleotropical flora that thrived during the Tertiary period. Altitudinal gradient acts as a natural testing ground for studying climate change, and research on the distribution patterns of microorganisms along altitudinal gradients is crucial in understanding the adaptability of D. involucrata to climate change. In our study, we examined sample sites ranging from 1600 to 2200 m in elevation, which are part of the primary habitat zone for Davidia involucrata within the Xuebaoding National Nature Reserve. In 2021, field surveys were conducted across four altitudinal gradients (1600 m, 1800 m, 2000 m and 2200 m) of the D. involucrata distribution in the nature reserve. The sampling plots were set in each altitudinal gradient, and three representative and healthy mature trees were selected as sample trees for each plot. Rhizosphere soils were used to test the soil stoichiometry characteristics and root zone microbial communities. Our findings indicated pronounced differences in soil total carbon (TC) and total phosphorus (TP) content and C:P and N:P ratios between the four altitude sites (p < 0.05). Analysis of the bacterial communities revealed higher richness (PD and Chao1 indexes) at ASL2000 and ASL2200 (high altitude) compared to ASL1600 and ASL2000 (low altitude) (p < 0.05). Non-metric multidimensional scaling analysis demonstrated a distinct clustering of bacterial communities between the high and low altitudes (p < 0.01). At the phylum level, Proteobacteria and Acidobacteria were predominant at high altitudes, while Actinobacteria and Chloroflexi dominated at low altitudes. The core microbiome, shared among all altitudes, comprised 377 genes. The analysis of differential abundance revealed notable disparities in the prevalence of certain bacterial genera with altitude, with Arthrobacter and Acidothermus experiencing the most pronounced shifts (p < 0.05). This confirmed that environmental factors significantly influenced bacterial community structure and abundance. Spearman’s rank correlations revealed that both Chao1 and PD indices were positively correlated with elevation, TC, and TN, with Chao1 showing stronger relationships. Both indices were negatively correlated with MAT, while only Chao1 exhibited a significant negative correlation with pH. Linear regression analysis further confirmed the significant associations between Chao1 index and elevation, TN, MAT, and pH. Furthermore, redundancy analysis demonstrated that altitude (ASL) and TN were the primary factors shaping soil bacterial community composition, explaining 21.32% and 30.70% of the variance, respectively. Altitude significantly influenced microbial community structure (p = 0.003). Distinct microbial taxa showed specific associations with environmental gradients, suggesting niche specialization in response to soil conditions. These findings suggest that altitude influences soil nutrient characteristics and microbial community composition in the D. involucrata habitat, offering insights into the ecological factors affecting this endangered species.

The effect of urbanization on freshwater macroinvertebrates – Knowledge gaps and future research directions

Metabarcoding of environmental samples is nowadays an established method in biodiversity research. When it comes to studying fungal populations in various ecotypes, fruit body inventories are the traditional method to assess the diversity of fungal communities. In this study, both methods-metabarcoding of soil samples and a traditional fruit body inventory-were conducted on 144 sample plots in an altitudinal gradient in the Bavarian Forest (Germany) and the results were compared. Metabarcoding detected significantly more species than the traditional fruit body inventory. The majority of taxa recorded in the fruit body inventory belonged to the Basidiomycota, whereas in the metabarcoding data, the distribution of species between Basidiomycota and Ascomycota was approximately balanced. Species of several orders forming inconspicuous or hypogeous fruit bodies were detected only by metabarcoding, while several wood decomposers were recorded only in the fruit body inventory. The proportion of detected wood-colonising species with melanized spores was considerably higher with metabarcoding than with the fruit body inventory, where more than 70% of recorded wood-colonisers had hyaline spores. Based on the metabarcoding data, a decline of species richness with increasing altitude was evident, but this was not visible in the fruit body inventory data. Detrended correspondence analyses yielded similar results for relative species community similarities with both survey methods.

Entre os mamíferos que ocorrem ao longo de todo gradiente altitudinal em montanhas no sudeste do Brasil (i.e. Mata Atlântica), os morcegos podem ser um excelente modelo de análise, porque são abundantes e apresentam todas as guildas. Nas cadeias de montanhas ao redor do mundo, a comunidade de morcegos pode apresentar dois padrões de riqueza e diversidade de espécies: 1) declínio progressivo na riqueza e diversidade de espécies à medida que a altitude aumenta; ou 2) um pico de riqueza e diversidade no nível altitudinal intermediário. Nesse contexto, o presente estudo teve como objetivo realizar um levantamento das espécies de morcegos ocorrentes nos fragmentos localizados na bacia do rio Itabapoana verificando a influência do gradiente altitudinal nas taxas de capturas dos morcegos. Para a captura dos morcegos, utilizamos redes de neblina, armadas no nível do solo, totalizando um esforço amostral de 1.500 m2/ha para cada localidade. A região do rio Itabapoana apresentou uma elevada riqueza de espécies de morcegos (26 espécies), abrigando 44% das espécies já registradas no Espírito Santo. Nosso estudo mostrou que existe uma variação nas taxas de captura de morcegos e riqueza de espécies, com uma reposição de algumas espécies, ao longo do gradiente altitudinal na região do rio Itabapoana. As mudanças na heterogeneidade do habitat ao longo desse gradiente são provavelmente um dos fatores ecológicos fortes que afetam esses parâmetros. Além disso, os dados desse estudo permitem a expansão do conhecimento das espécies de morcegos que ocorrem na região do Itabapoana. A diversidade de espécies encontrada, juntamente com a ocorrência de espécies raras, destaca a importância da região para a conservação ajudando a entender os padrões de distribuição das espécies.

Aim To study the altitudinal variation of ground spiders (Araneae, Gnaphosidae) of Crete, Greece, as far as species composition, species richness, activity and range of distribution are concerned.Location Altitudinal zones (0–2400 m) along the three main mountain massifs of the island of Crete.Methods Thirty‐three sampling sites were located from 0 to 2400 m a.s.l. on Crete, and sampled using pitfall traps. Material from the high‐activity period of Gnaphosidae (mid‐spring to mid‐autumn) was analysed. Sampling sites were divided into five altitudinal zones of 500 m each. Statistical analysis involved univariate statistics (anova) and multivariate statistics, such as multidimensional scaling (MDS) and cluster analysis (UPGMA) using binomial data of species presence or absence.Results Species richness declines with altitude and follows a hump‐shaped pattern. The activity pattern of the family, as a whole, is not correlated with altitude and is highly species‐specific. In the highest zone, both species richness and activity decline dramatically. The altitudinal range of species distribution increases with altitude. On the Cretan summits live highly tolerant lowland species and isolated residents of the high mountains of Crete. Two different patterns of community structure are recorded.Main conclusions Communities of Gnaphosidae on Crete present two distinct structures following the altitudinal gradient, these being separated by a transitional zone between 1600 and 2000 m. This study supports previous results which show a hump‐shaped decline in species richness of Gnaphosidae along altitudinal gradients, leading to a peak at 400–700 m, where an optimum of environmental factors exists. This makes this zone the meeting point of the often opportunistic lowland species with the older and most permanent residents of the island. Rapoport's rule on the positive correlation of the altitudinal range of species distributions with altitude is also supported. The high activity recorded for the species that persist on the high mountains of Crete is indicative of a tolerant arachnofauna, and is considered to result from relaxation of competitive interactions with other species. This is related to a reduction in species numbers, shortening of the activity period on high mountains and the unique presence of high mountain species that thrive only there. As shown in our study, strategies to cope with altitude are species‐specific. Therefore, there cannot exist one single model to describe how animals react to the change in altitude, even under the same environmental conditions.

Climate and geochemistry at different altitudes influence soil fungal community aggregation patterns in alpine grasslands

We studied the altitudinal distribution of 426 bird species in the Serra dos Orgaos, a mountainous region in southeastern Brazil. Thirty-four localities were visited between 1991 and 2009. Our study revealed a decline in bird species richness with elevation, although a smaller number of species was recorded at lower altitudes (below 300 m) possibly due to local extinctions caused by the intense human occupation of the region. A less diverse avifauna was found above 2,000 m, with only one species (Caprimulgus longirostris) recorded exclusively in this altitudinal range. Most endemic species were found between 300 and 1,200 m, but the endemism was more significant at higher altitudes. Nearly half of the birds found above 1,400 m were endemic species. Most of the threatened species from the state of Rio de Janeiro recorded in our study were found below 1,200 m, but no significant difference was found between the proportions of threatened species among different altitudinal ranges. Species of seventeen genera have exhibited some replacement (sometimes with partial overlap) along altitudinal gradients.

Widespread plants may provide natural models for how population processes change with temperature and other environmental variables and how they may respond to global change. Similar changes in temperature can occur along altitudinal and latitudinal gradients, but hardly any study has compared the effects of the two types of gradients. We studied populations of Anthyllis vulneraria along a latitudinal gradient from Central Europe to the range limit in the North and an altitudinal gradient in the Alps from 500 m to the altitudinal limit at 2500 m, both encompassing a change in annual mean temperature of c. 11.5 °C. Plant size and reproduction decreased, but plant density increased along both gradients, indicating higher recruitment and demographic compensation among vital rates. Our results support the view that demographic compensation may be common in widespread species in contrast to the predictions of the abundant centre model of biogeography. Variation in temperature along the gradients had the strongest effects on most population characteristics, followed by that in precipitation, solar radiation, and soil nutrients. The proportion of plants flowering, seed set and seed mass declined with latitude, while the large variation in these traits along the altitudinal gradient was not related to elevation and covarying environmental variables like annual mean temperature. This suggests that it will be more difficult to draw conclusions about the potential impacts of future climate warming on plant populations in mountains, because of the importance of small-scale variation in environmental conditions.

Agricultural activity associated with habitat conversion is a major driver of biodiversity loss across the tropics. The decline of species richness is a common outcome of conversion to agricultural land use, but the associated changes in functional and phylogenetic diversities, and spatial patterns of beta diversity, are not well understood. These patterns may shed light on underlying ecological processes that are of both basic and applied interest; for example the relative roles of stochastic assembly, ecological filtering, and competition in structuring ecological communities as well as broader consequences for ecological functioning in agroecosystems. Here we investigate the effects of conversion to rubber plantation (Hevea brasiliensis), a rapidly spreading agroecosystem in Southeast Asia, on leaf‐litter ant taxonomic, functional, and phylogenetic diversities at local and among‐sites scales in Xishuangbanna, Southeast China. We found a sharp decline of ant species richness in rubber plantations compared with nearby forest habitat, with low beta diversity indicating spatial homogeneity of communities in rubber plantations. In addition, patterns of both functional alpha and beta diversities suggested the emergence of a functionally distinct ant community in the agroecosystem compared to the forest habitats. These results support a role of ecological filtering in structuring the taxonomic and functional composition of both rubber and forest habitats. In contrast, changes in phylogenetic diversity were modest and not significantly different from random expectations despite strong phylogenetic signal of functional traits. This study highlights the need for a pluralistic approach to characterizing the loss of biodiversity in agroecosystems, as well as understanding the underlying mechanisms of community assembly driving this biodiversity loss.