Vascular plant diversity and climate change in the alpine zone of the Lefka Ori,Crete

The aim of this study is to analyse the vascular flora and the local climate along an altitudinal gradient in the Lefka Ori massif Crete and to evaluate the potential effects of climate change on the plant diversity of the sub-alpine and alpine zones. It provides a quantitative/qualitative analysis of vegetation-environment relationships for four summits along an altitude gradient on the Lefka Ori massif Crete (1664–2339 m). The GLORIA multi-summit approach was used to provide vegetation and floristic data together with temperature records for every summit. Species richness and species turnover was calculated together with floristic similarity between the summits. 70 species were recorded, 20 of which were endemic, belonging to 23 different families. Cretan endemics dominate at these high altitudes. Species richness and turnover decreased with altitude. The two highest summits showed greater floristic similarity. Only 20% of the total flora recorded reaches the highest summit while 10% is common among summits. Overall there was a 4.96°C decrease in temperature along the 675 m gradient. Given a scenario of temperature increase the ecotone between the sub-alpine and alpine zone would be likely to have the greatest species turnover. Southern exposures are likely to be invaded first by thermophilous species while northern exposures are likely to be more resistant to changes. Species distribution shifts will also depend on habitat availability. Many, already threatened, local endemic species will be affected first.     

Vascular plant diversity and climate change in the alpine zone of the Snowy Mountains,Australia

This study examines vascular plant species richness along an altitudinal gradient in alpine Australia. Vascular plant composition and soil temperature records were obtained for five summits (from 1729 m to 2114 m a.s.l.) using sampling protocols from the Global Observation Research Initiative in Alpine Environments program. Species richness was examined against altitude, aspect and climatic variables at different spatial scales (10 × 10 cm quadrats, 1 m² quadrats, clusters of 4 * 1 m² quadrats, for the summit area above a line 5 m altitudinally below the summit (the −5 m isoline), for the extended summit down to the −10 m isoline). About 75 taxa (70 species, 5 graminoid genera) were recorded, 9 of which are endemic to the small alpine area of ∼100 km². There were significant linear relationships between species richness and altitude and climatic variables for the top to −5 isolines on the summits. However, there was no consistent pattern for species richness at other spatial scales, altitude, aspect or climatic variables. The proportion of species for the whole summits with localised distributions (local endemics) increased with altitude. Predicted increasing temperatures and reduced snowcover is likely to result in an increase in species richness as shrubs, herbs and introduced weeds become more common at higher altitude. Because Australian alpine areas occur in narrow altitudinal bands with no nival zone, there are no higher altitudinal refuges available for alpine species. Therefore many of these species are likely to be at risk of extinction from climate change.     

Short-term signals of climate change along an altitudinal gradient in the South Alps

Short-term changes in plant species number, frequency and composition were studied along an altitudinal gradient crossing four summits from the treeline ecotone to the subnival zone in the South Alps (Dolomites, Italy). Large-scale (summit areas) and small-scale patterns (16 plots of 1 m2/summit) were monitored. After 5 years, a re-visitation of the summit areas revealed a considerable increase of species richness at the upper alpine and subnival zone (10% and 9%, respectively) and relatively modest increases at the lower alpine zone and the treeline ecotone (3% and 1%, respectively). At the small scale, the results were partly different, with species richness decreasing at the lower summits and increasing at the higher summits. The changes can most likely be attributed to climate warming effects and to competitive interactions. The main newcomers at the lower three summits were species from the treeline and the lower altitudinal zones. Only at the highest summit, the newcomers came from the alpine species pool. At the treeline ecotone, the abundance of Pinus cembra, of dwarf shrubs and clonal graminoid species increased. Here, displacements of alpine species may be predicted for the near future. At the higher summits, expansions of the established alpine species and further invasions of species from lower altitudes are forecasted.     

Signals of range expansions and contractions of vascular plants in the high Alps: observations (1994–2004) at the GLORIA* master site Schrankogel,Tyrol, Austria

High mountain ecosystems are defined by low temperatures and are therefore considered to react sensitively to climate warming. Responding to observed changes in plant species richness on high peaks of the European Alps, an extensive setup of 1 m × 1 m permanent plots was established at the alpine‐nival ecotone (between 2900 and 3450 m) on Mount Schrankogel, a GLORIA master site in the central Tyrolean Alps, Austria, in 1994. Recording was repeated in a representative selection of 362 quadrats in 2004. Ten years after the first recording, we observed an average change in vascular plant species richness from 11.4 to 12.7 species per plot, an increase of 11.8% (or of at least 10.6% at a 95% confidence level). The increase in species richness involved 23 species (about 43% of all taxa found at the ecotone), comprising both alpine and nival species and was pronouncedly higher in plots with subnival/nival vegetation than in plots with alpine grassland vegetation. Only three species showed a decrease in plot occupancy: one was an annual species, one was rare, and one a common nival plant that decreased in one part of the area but increased in the uppermost part. Species cover changed in relation to altitudinal preferences of species, showing significant declines of all subnival to nival plants, whereas alpine pioneer species increased in cover. Recent climate warming in the Alps, which has been twice as high as the global average, is considered to be the primary driver of the observed differential changes in species cover. Our results indicate an ongoing range contraction of subnival to nival species at their rear (i.e. lower) edge and a concurrent expansion of alpine pioneer species at their leading edge. Although this was expected from predictive distribution models and different temperature‐related habitat preferences of alpine and nival species, we provide first evidence on – most likely – warming‐induced species declines in the high European Alps. The projected acceleration of climate warming raises concerns that this phenomenon could become the major threat to biodiversity in high mountains.     

Shift in soil–plant nitrogen dynamics of an alpine–nival ecotone

We investigated the nitrogen (N) dynamics of an alpine–nival ecotone on Mt. Schrankogel, Tyrol, Austria, in relation to temperature. Natural abundance of ¹⁵N was used as a tool to elucidate differences in N cycling along an altitudinal transect ranging from 2,906 to 3,079 m, corresponding to a gradient in mean annual temperature of 2.4 °C. The amount of total soil N, of plant available N and soil C/N ratio decreased significantly with increasing altitude, whereas soil pH increased. Soil δ ¹⁵N decreased with increasing altitude from +2.2 to −2.1‰ and δ ¹⁵N of plant tissues (roots and leaves) decreased from −3.7 to −5.5‰. The large shift in soil δ ¹⁵N of 4.3‰ from the lowest to the highest site suggested substantial differences in N cycling in alpine and nival ecosystems in the alpine nival ecotone investigated. We concluded that N cycling at the alpine–nival ecotone is likely to be controlled by various factors: temperature, soil age and development, atmospheric N deposition and plant competition. Our results furthermore demonstrate that the alpine–nival ecotone may serve as a sensitive indicator of global change.     

Changes in the Altitudinal Distribution of Alpine Plants in Katunskiy Biosphere Reserve (Central Altai) Revealed on the Basis of Multiyear Monitoring Data

In order to reveal climate-related changes in the plant diversity of alpine ecosystems in recent decades, a target region of the GLORIA (Global Observation Research Initiative in Alpine Environments) worldwide network consisting of four mountain summits representing an elevation gradient from the subalpine to the upper part of alpine ecotone (2181, 2231, 2358, and 2475 m above sea level) has been established in Katunskiy Biosphere Reserve (Russia, Central Altai). In the course of the observation period (2005–2015), species in the target region have shifted towards higher altitudes by 5.3 m on average. The plant species richness has increased on the three higher summits and decreased on the lowest summit.     

Diaspore traits discriminate good from weak colonisers on high-elevation summits

The richness of plant species in Swiss alpine-nival summits increased during the climate warming of the 20th century. Thirty-seven summits (2797–3418 m a.s.l.) with both old (～1900–1920) and recent (～2000) plant inventories were used to test whether biological species traits can explain the observed rates of summit colonisation. Species were classified into two groups: good colonisers (colonising five or more summits) and weak colonisers (fewer than five new summits). We compared species traits related to growth, reproduction and dispersal between these two groups and between the good colonisers and a group of high alpine grassland species. The observed colonisation pattern was subsequently compared with a simulated random colonisation pattern.The distribution of new species on the summits was not random, and 16 species exhibited a colonisation rate higher than expected by chance. Taraxacum alpinum aggr. and Cardamine resedifolia were the best colonisers. Results showed that diaspore traits enhancing long-distance dispersal were more frequent among good colonisers than among weak colonisers. Good colonisers were mostly characterised by pappi or narrow wings on their diaspores. Both groups were able to grow on soils more bare and rocky than species from the alpine grasslands. All other biological traits that we considered were similar among the three alpine species groups. These results are important for improving predictive models of species distribution under climate change.     

Upward migration of vascular plants following a climate warming trend in the Alps

The aim of this study was to understand (1) whether warmer climatic conditions affected the vascular plant species composition, (2) the magnitude and rate of altitudinal changes in species distributions, and (3) whether an upward migration of alpine plants is connected to wind dispersal of diaspores. We compared historical records (1954–1958) with results from recent plant surveys (2003–2005) from alpine to nival ecosystems in the Rhaetian Alps, N-Italy. The presence of all vascular plant species and their maximum altitude were recorded along a continuous altitudinal transect of 730 m. An increase in species richness from 153 to 166 species was observed. Moreover, 52 species were recorded from altitudes 30–430 m higher than their 1950s limits, which corresponds to a median migration rate of 23.9 m/decade. In order to explain the observed migrations, the species wind-dispersal ability (diaspore weight and morphology) and the air temperature variation from 1926 to 2003 were considered. Species with more pronounced altitudinal shifts possess lighter diaspores. The highest increase in species richness was found between 2800 and 3100 m a.s.l.; this appears to be related to an estimated shift of the permafrost limit by +240 m during the last 50 years. The mean air temperature in the region rose by +1.6 °C in summer and by +1.1 °C in winter within this period. Climate warming is therefore considered as a primary cause of the observed upward migration of high mountain plants. Calculated altitudinal migration rates, however, varied remarkably among species. This would imply differential abilities of species to persist in an increasingly warmer climate. Species-specific conservation measures, including ex situ conservation, may therefore be required.     

Vascular plant diversity and climate change in the upper zone of Sierra Nevada,Spain

Abstract

This study examines the effects of altitudinal, temperature and aspect gradients on vascular plant species richness on mountain tops in Sierra Nevada (Spain) at different spatial scales (1 m² quadrats, plot clusters of 4 m², upper summit area down to the 5-m contour line, entire summit down to the 10-m contour line). The methodology follows the Global Observation Research Initiative in Alpine Environments (GLORIA) programme. Floristic and soil temperature data of eight summits sites in two neighbouring regions of the high part of Sierra Nevada (from 2668 m to 3327 m a.s.l.) were used in this study. In total, 102 taxa were recorded (84 genera; 29 families). The species richness decreased, whereas the proportion of endemic taxa increased with elevation. There were significant linear relationships between species richness and altitude and average soil temperature at each spatial scale. However, there was no significant relationship between species richness and aspect variables. Facing continued climate change, the high-altitude flora of Sierra Nevada is expected to be particularly vulnerable and prone to warming-induced biodiversity losses due to the high proportion of endemic taxa, ranging from 23% at lower elevations up to 67% at higher ones.     

Upward shift of alpine plants increases floristic similarity of mountain summits

Question: Does the upward shift of species and accompanied increase in species richness, induced by climate change, lead to homogenization of Alpine summit vegetation? Location: Bernina region of the Swiss Alps. Methods: Based on a data set from previous literature we expand the analysis from species richness to beta‐diversity and spatial heterogeneity. Species compositions of mountain summits are compared using a two‐component heterogeneity concept including the mean and the variance of Sørensen similarities calculated between the summits. Non‐metric multidimensional scaling is applied to explore developments of single summits in detail. Results: Both heterogeneity components (mean dissimilarity and variance) decrease over time, indicating a trend towards more homogeneous vegetation among Alpine summits. However, the development on single summits is not strictly unidirectional. Conclusions: The upward shift of plant species leads to homogenization of alpine summit regions. Thus, increasing alpha‐diversity is accompanied by decreasing beta‐diversity. Beta‐diversity demands higher recognition by scientists as well as nature conservationists as it detects changes which cannot be described using species richness alone.     

Vascular plant diversity and climate change in the alpine belt of the central Apennines (Italy)

The aim of this study is to analyse the vascular flora and the local climate along the altitude gradient in the largest alpine belt of the central Apennines (Majella National Park), and to contribute to the evaluation of the possible effects of global climate changes on the biodiversity of the alpine ecosystem. For this purpose floristic-quantitative analyses and temperature records on three different summits have been carried out by using the methodological protocol of the UE-GLORIA project (2001 2003); the project aims toward a standardised monitoring of flora and temperature in the alpine environment of the main European chains. From the analysis of the changes in species richness along the altitude gradient (2405 m versus 2730 m a.s.l.), it emerged that 70% of species do not reach the highest summit and only 11% of the overall flora is shared by all of the summits examined; a drop in mean temperature has been observed at soil level, along the same gradient from 3.11 to 0.03 °C. Floristic-quantitative and climatic analyses have been carried out even along the horizontal gradient (principal exposures), highlighting a great species richness and vegetation cover in eastward aspects. We singled out some endangered rare species and we proved that the slopes facing east will be the first to be affected by the coming of subalpine species from below, whereas northward exposures will be the most conservative, showing greater inertia toward the invasive process caused by the climate warming.     

Latitudinal and altitudinal patterns of plant community diversity on mountain summits across the tropical Andes

The high tropical Andes host one of the richest alpine floras of the world, with exceptionally high levels of endemism and turnover rates. Yet, little is known about the patterns and processes that structure altitudinal and latitudinal variation in plant community diversity. Herein we present the first continental‐scale comparative study of plant community diversity on summits of the tropical Andes. Data were obtained from 792 permanent vegetation plots (1 m²) within 50 summits, distributed along a 4200 km transect; summit elevations ranged between 3220 and 5498 m a.s.l. We analyzed the plant community data to assess: 1) differences in species abundance patterns in summits across the region, 2) the role of geographic distance in explaining floristic similarity and 3) the importance of altitudinal and latitudinal environmental gradients in explaining plant community composition and richness. On the basis of species abundance patterns, our summit communities were separated into two major groups: Puna and Páramo. Floristic similarity declined with increasing geographic distance between study‐sites, the correlation being stronger in the more insular Páramo than in the Puna (corresponding to higher species turnover rates within the Páramo). Ordination analysis (CCA) showed that precipitation, maximum temperature and rock cover were the strongest predictors of community similarity across all summits. Generalized linear model (GLM) quasi‐Poisson regression indicated that across all summits species richness increased with maximum air temperature and above‐ground necromass and decreased on summits where scree was the dominant substrate. Our results point to different environmental variables as key factors for explaining vertical and latitudinal species turnover and species richness patterns on high Andean summits, offering a powerful tool to detect contrasting latitudinal and altitudinal effects of climate change across the tropical Andes.     

Establishing a baseline of plant diversity and endemism on a neotropical mountain summit for future comparative studies assessing upward migration: an approach from biogeography and nature conservation

Climate change is forcing many plant species to shift their range in search of adequate environmental conditions, being localized endemic species particularly at risk on mountain summits. The Pantepui biogeographic province, a set of flat-topped mountain summits (called tepuis) of northern South America, contains both high plant diversity and a high degree of endemism. Previous studies based on warming projections for the area suggested that half of the Pantepui endemic flora would disappear due to habitat loss by 2100. In this study, we selected one of the best-explored tepuis, Roraima-tepui, to establish the baseline of diversity and endemism for comparisons with historical data and future monitoring surveys, aimed at testing the hypothesis of upward migration of plants in response to global warming. We also analysed floristic and physiognomic features of the Eastern Tepui Chain (ETC, the mountain range where Roraima is located), and the phytogeographic patterns of both the ETC and Pantepui. The Roraima summit contains 227 species, including 44 new records, 13 exotic species (some of them with high invasive potential), and at least one species new to science. At the ETC level, Roraima is the tepui with highest species richness and degree of endemism, and shows a relatively high floristic similarity with Kukenán and Ilú. Herbaceous species dominate over shrubs on these tepuis, Tramen and Maringma, whereas on Yuruaní, Karaurín and Uei, they reach similar abundances. At the Pantepui level, endemic species have highly localized distribution patterns (17% local endemics). Conservation opportunities are evaluated in light of these results.     

The subnival–nival vascular plant species of Iran: a unique high-mountain flora and its threat from climate warming

This study provides a first country-wide overview of the vertical distribution patterns and the chorology of vascular plant species that occur in the uppermost elevation zones in Iran. The current distribution patterns are discussed with respect to potential warming-induced species losses. Iran’s subnival and nival vegetation zones are found at elevations above 3600–3900 m in a highly fragmented distribution across Alborz, Zagros, and NW-Iran. Based on literature research and on field observations, all vascular plant species living in the subnival–nival zone of Iranian mountains were identified (151 species) and classified into three altitudinal groups: Group A comprises species that occur mainly in subnival–nival habitats (51 species). Group B are species being common in subnival–nival areas but are equally present in the alpine zone (56 species). Group C are species that can reach to subnival areas but also grow in alpine, subalpine and sometimes lower altitudes (44 species). The chorological patterns differ among the three groups. The percentage of species being endemic to Iran decreases from group A, to B and C, with 68, 53 and 20%, respectively. A narrow altitudinal distribution at high elevations is clearly related to a small-scaled geographical distribution range. The outstanding rate of high-altitude endemism appears to result mainly from orographic isolation of the country’s highly scattered cold areas and by the absence of extensive Pleistocene glaciations. The narrow distribution of most of Iran’s cold-adapted mountain flora and the low potential of alternative cold habitats render it highly vulnerable to climate change.     

Traditional Knowledge and Useful Plant Richness in the Tehuacán–Cuicatlán Valley,Mexico

Traditional Knowledge and Useful Plant Richness in the Tehuacán–Cuicatlán Valley, Mexico. This study systematizes ethnobotanical information about the interactions between people and plants, ethnofloristic richness, the relative importance of useful species richness in relation to general species richness, and plant management in the Tehuacán–Cuicatlán Valley of central Mexico. The study recorded a total of 1,605 useful vascular plant species (61.2% of the total species richness of the regional vascular flora), this being the region with the highest absolute richness of useful plant species in Mexico. The null hypothesis that plant families with a higher number of useful species would be those having a higher general species richness was analyzed through residuals method. The plant families richest in useful species were Poaceae, Asteraceae, Cactaceae, Cyperaceae, Mimosaceae, and Solanaceae, most of which also have the highest general floristic richness. However, analyses of use categories did not generally corroborate our hypothesis. About 1,335 of the useful species are wild, more than 500 species are submitted to some type of management (62 species are tolerated, 34 protected, 50 enhanced, and 358 cultivated), but only a few have been studied to document their process of domestication. This information can be useful for developing regional strategies of sustainable management of plant resources.     

Short-term variation in species richness across an altitudinal gradient of alpine summits

In response to climate warming, high altitude alpine vegetation may be replaced by typically lower altitude species, as species re-assemble and migrate to new areas. However, empirical evidence showing vegetation change in response to climate warming is largely unavailable for Australian alpine areas. Here, we examine changes in species richness with respect to climate and altitude over a 7?year period at a range of spatial scales in a re-survey of five alpine summits that are part of the Global Observation Research Initiative in Alpine Environments monitoring network. Eighty species were recorded in 2011 across all summits, an increase of 6 species since 2004. Mean species richness increased at the whole-of-summit scale from 45 to 50 species (about 12?%). At this scale, the rate of species richness increase was almost one new species per year, with 15 new species recorded at one summit. Here, shrub and graminoid species showed the largest increases. At the smaller spatial scales, changes in species richness were less pronounced. Turnover at the species and community level was typically moderate at all spatial scales and on all summits. The strength and direction of species richness change (the difference in species richness between the two sample periods, +/?) was not related to altitude nor variation in climate. Future re-surveys of the summits will confirm whether these short-term variations in species richness, particularly increases in shrubs, are indeed signals of longer-term trends and interactions with a changing climate.     

Does cross-taxon analysis show similarity in diversity patterns between vascular plants and bryophytes? Some answers from a literature review

The objective of this study was to clarify the taxon surrogacy hypothesis relative to vascular plants and bryophytes. A literature review was conducted to obtain papers that met the following criteria: (i) they examined species richness values; or (ii) they evaluated the species richness within the same study sites, or under the same spatial variation conditions. Twenty-seven papers were accessed. The richness of the two taxa, compared in 32 cases, positively co-varied in about half of the comparisons. The response to the spatial variation in environmental or human-induced factors of the two taxa in terms of species richness was rather variable. Based on current knowledge, the main documented findings regard forest habitats and nival gradients. In forest habitats, co-variation in species richness is likely when similar environments are analysed and seems to be strengthened for boreal forests. Along the nival gradient, a different response in terms of richness of the two taxa suggests that vascular plants cannot be considered good surrogates for bryophytes.     

Reproducibility of species lists,visual cover estimates and frequency methods for recording high‐mountain vegetation

Question: When multiple observers record the same spatial units of alpine vegetation, how much variation is there in the records and what are the consequences of this variation for monitoring schemes to detect changes? Location: One test summit in Switzerland (Alps) and one test summit in Scotland (Cairngorm Mountains). Method: Eight observers used the GLORIA protocols for species composition and visual cover estimates in percentages on large summit sections (>100 m²) and species composition and frequency in nested quadrats (1 m²). Results: The multiple records from the same spatial unit for species composition and species cover showed considerable variation in the two countries. Estimates of pseudo‐turnover of composition and coefficients of variation of cover estimates for vascular plant species in 1 m × 1‐m quadrats showed less variation than in previously published reports, whereas our results in larger sections were broadly in line with previous reports. In Scotland, estimates for bryophytes and lichens were more variable than for vascular plants. Conclusions: Statistical power calculations indicated that unless large numbers of plots were used, changes in cover or frequency were only likely to be detected for abundant species (exceeding 10% cover) or if relative changes were large (50% or more). Lower variation could be reached with the point method and with larger numbers of small plots. However, as summits often strongly differ from each other, supplementary summits cannot be considered as a way of increasing statistical power without introducing a supplementary component of variance into the analysis and hence into the power calculations.     

Vegetation composition,structure and soil properties across coastal forest–barren ecotones

Coastal barrens support rare plant species but may be threatened by forest encroachment. We determined whether trees spread into coastal barren habitat from forest patches and assessed plant species composition and soil properties across the forest–barren ecotone. We quantified tree age and height, soil properties, and vascular plant, bryophyte and lichen species composition along transects perpendicular to the edges of tree patches within the forest–barren ecotone in coastal Nova Scotia. Randomization tests assessed whether the vegetation and environmental characteristics were significantly different in the transition zone compared to one or both adjoining ecosystems. We used ordination to examine trends in species composition across the ecotone and the relationship to environmental variables. Tree age and height decreased continuously from the forest towards the edge of the forest patches. There were also trends in vegetation composition and structure from the forest into the open barrens. Many species were most abundant within the transition zone, although not always significantly. Soil properties were relatively uniform across the ecotone. The structure and vegetation of the forest–barren ecotone suggests that forest patches act as nuclei for forest expansion on barrens with a typical successional pathway where coastal barren vegetation is gradually replaced by forest species. This encroachment may pose a threat to rare barrens communities. While landscape factors such as salt spray and wind exposure may determine the general locations where forest can establish, biotic processes of growth and dispersal appear to govern the fine-scale expansion of tree patches.     

Species richness of vascular plants,bryophytes, and lichens along an altitudinal gradient in western Norway

Species richness patterns of ground-dwelling vascular plants, bryophytes, and lichens were compared along an altitudinal gradient (310–1135 m a.s.l.), in western Norway. Total species richness peaked at intermediate altitudes, vascular plant species richness peaked immediately above the forest limit (at 600–700 m a.s.l.), bryophyte species richness had no statistically significant trend, whereas lichen richness increased from the lowest point and up to the forest limit, with no trend above. It is proposed that the pattern in vascular plant species richness is enhanced by an ecotone effect. Bryophyte species richness responds to local scale factors whereas the lichen species richness may be responding to the shading from the forest trees.