Alpine Botany最新文献

Patterns of flowering phenology, i.e. first and last flowering day (FFD and LFD) and flowering duration (FD) govern plant pollination and reproduction. Most research has focused on FFD whereas LFD, FD and second flowering events were neglected although they are crucial events. To assess whether flowering patterns change species-specifically with changing abiotic conditions and whether these are related to leaf persistence, reproduction and pollination syndrome, we monitored flowering phenology (including also second flowering events) of 29 herbaceous species along two elevational gradients ranging from 700 to 1800 m a.s.l. in two consecutive years. FFD was delayed with increasing elevation. LFD followed two alternative strategies: species which ceased flowering early in the season delayed LFD with increasing elevation, species which ceased flowering late did not change LFD. FD decreased with increasing elevation in most species. The timing of flowering phenology had strong influences on the intensity of change along the elevational gradient and other stages of flowering phenology. Many species showed a second flowering event which occurred irrespective of elevation, suggesting a link to unsuccessful pollination rather than temperature. Life history strategies helped explain patterns of flowering phenology and a species’ ability to track changes in abiotic conditions, e.g. evergreen species started to flower earlier than summer green species and insect-pollinated species were able to expand FD most. These findings give insight into species-specific changes in phenological patterns and thus plant performance with changing environment. They should be considered when assessing the consequences of environmental change at both the community and ecosystem level.

The largest alpine–nival vegetation permanent plot site in the Alps, the GLORIA mastersite Schrankogel (Tirol, Austria), provided evidence of warming-driven vegetation changes already 10 years after its establishment in 1994. Another decade later, in 2014, substantial compositional changes with increasing ratios of warmth-demanding to cold-adapted species have been found. The current study deals with species-specific responses involved in an ongoing vegetation transformation across the alpine–nival ecotone on Schrankogel by using presence/absence as well as cover data from permanent plots, situated between 2900 and 3400 masl. The number of occupied plots per species remained constant or even increased during the first decade, whereas disappearance events became more frequent during the second one, especially for cold-adapted specialists (subnival–nival species). Remarkably, the latter was accompanied by continued strong losses in cover of all subnival–nival species. These losses were more frequent in plots with a more thermophilous species composition, suggesting an increasing maladaptation of subnival–nival species to warmer habitat conditions and a successive trailing-edge decline. Several species with a distribution centre at lower elevations (alpine–subnival) markedly increased in cover, comparatively more so in colder plots, indicating a leading-edge expansion. Moreover, our findings show an increase in occupied plots and cover of almost all snowbed species, suggesting that areas previously with a too long snowpack period are now becoming suitable snowbed habitats. Vegetation gaps arising from population dieback of cold-adapted species, however, could only be partly filled by advancing species, indicating that species declines have occurred already before the onset of strong competition pressure.

Diversity patterns of tropical alpine vegetation is poorly studied. We estimated vascular plant floristic richness for two typical afro-alpine communities in Mount Kenya using a series of nested plots sized from 25 to 100 m². The α-diversity was low for all plot sizes (4.8–7.8 and 12.8 species per one and 100 m², respectively). Comparative analysis of α-, β- and γ-diversity across 22 plant communities from five Mountain regions (Mount Kenya, European Alps, Caucasus, Tibet, New Zealand Alps) revealed that area of mountain system was the only significant variable shaping the local richness; this effect became stronger with increasing spatial scale. Beta-diversity, by contrast, showed neither latitudinal trends nor significant correlation with other geographical or climatic variables. We conclude that the total area of mountain system is one of the main factors determining the regional species pool and, ultimately, the local diversity of alpine plant communities (the “echo-effect”). Small area and isolation of Mt. Kenya are considered as the main reasons for low local richness of its afro-alpine vegetation.

Climate change has resulted in shorter periods of snow cover in alpine meadows, increasing the duration of UV exposure. We established the relationship between increased exposure to UV light and anthocyanin pigment levels in host plant Sedum lanceolatum and tested whether increased exposure changed the feeding behavior of its herbivore Parnassius smintheus. Anthocyanin concentrations were significantly greater in plants exposed to UV. Under field conditions, we found a preference of P. smintheus caterpillars for plants with slightly above average levels of anthocyanin; however, no-choice feeding experiments in which larvae ranging from 1 to 3 days old were placed on UV-rich and UV-low plants showed no difference in feeding. These results indicate that the reduction of snow cover in alpine meadows will change the pigment profile of plants, but these changes may have little effect on herbivory.

Leaf shape variations and developmental instability were examined for the first time in natural populations of Prunus avium (L.) L. in the central Balkan region (Bosnia and Herzegovina) at different elevational points, from 230 to 1177 m. above sea level. Geometric morphometric tools were applied to assess the variability of leaf shapes and sizes, while a fluctuating asymmetry leaf index was used as a measure of leaf developmental instability. According to the results of canonical variate analysis for the symmetric component of shape variation and hierarchical analysis of variance for centroid size, the studied populations could be partially differentiated into three groups. The co-variation between leaf form (shape and size) and climate variables was significant, estimated by two-block partial least square analysis. Climate variables (the sum of precipitation in May and the De Martonne aridity index) mostly influenced leaf shape and size. A population situated at the highest elevation had the highest value for fluctuating asymmetry leaf index, which was an indication of developmental instability. High natural variability and interpopulation differences were observed for all studied leaf traits (leaf shape, centroid size, fluctuating asymmetry leaf index, leaf area, leaf length and width, petiole length). For well-known traditional morphometric measures (leaf area, leaf length, leaf width, and petiole length) in accordance with previous studies, intrapopulation variability was greater than interpopulation variability. For centroid size and the fluctuating asymmetry leaf index (measures used in geometric morphometrics) variability was higher among populations than within them. This indicates that geometric morphometrics could give new insights into infra-specific variability.

The impacts of climate change on alpine summit floras have been widely investigated. However, only few studies included alpine grasslands and generally concluded that snowbeds, with a long snow cover duration and a short growing season, and windy ridges, with a short snow cover duration and strong winter frosts, are the most sensitive alpine grasslands. However, these habitats were mostly investigated in different regions, where local factors (e.g. nitrogen deposition, grazing) can co-vary with climate changes, potentially obscuring differences between habitats. Here, we focused on the Zermatt region (Swiss Alps) to investigate the impacts of climate change on snowbeds and windy ridges. Forty-three exhaustive historical plant inventories on windy ridges (acidophilic or basophilic) and 31 inventories in snowbeds (typical or wet) were repeated in quasi-permanent plots after approximately 23 years. Historical and recent records were compared with the Simpson index, Bray–Curtis dissimilarity, a PCA, ecological indicator values and the frequency and cover changes of species. There was a general increase in α-diversity and a decrease in β-diversity (homogenisation). Most of the new species in the plots were generalists from surrounding grasslands. The plant composition tended to be more thermophilous on acidophilic windy ridges and in typical snowbeds. The flora of acidophilic windy ridges became more similar to that of basophilic windy ridges and more eutrophic. We interpreted this as possibly arising from fertilisation by the aeolian dust deposition coming from the expanding glacial moraine in the valley. In snowbeds, the species indicated increasingly drier conditions, especially in wet snowbeds. Warming climate induces lower snowfall and earlier snowmelt, leading to a shorter snow cover duration. Hence, wet snowbeds are certainly among the most threatened plant communities by climate change in the Alps.

Climate refugia are locations where plants are able to survive periods of regionally adverse climate. Such refugia may affect evolutionary processes and the maintenance of biodiversity. Numerous refugia have been identified in the context of Quaternary climate oscillations. With climate warming, there is an increasing need to apply insights from the past to characterize potential future refugia. Mountainous regions, due to the provision of spatially heterogeneous habitats, may contain high biodiversity, particularly important during climate oscillations. Here, we highlight the importance of mountaintops as climate refugia, using the example of high-mountain oaks which are distributed on the ranges of the Himalaya–Hengduan Mountains, and at high elevations in tropical rainforests. The occurrences of cold-adapted high-mountain oaks on mountaintops amidst tropical rainforest indicate that such locations are and will be climate refugia as global warming continues. We examine factors that predict the occurrence of future climate refugia on mountaintops using recognized historical refugia. Future research is needed to elucidate the fine-scale processes and particular geographic locations that buffer species against the rapidly changing climate to guide biodiversity conservation efforts under global warming scenarios.

Pleistocene climatic changes affected the current distribution and genetic structure of alpine plants. Some refugial areas for the high elevation species have been proposed in the Alps, but whether they could survive on nunataks, is still controversial. Here, the spatial genetic structure in Salix serpillifolia revealed by chloroplast (cpSSR) and nuclear (nSSR) microsatellites was compared with the MaxEnt-modelled geographic distributions under current and past (Last Glacial Maximum) climate conditions. Our results suggest that the genetic pattern of differentiation detected in S. serpillifolia may be explained by the existence of Pleistocene refugia, including nunataks. The geographical patterns of variation obtained from the chloroplast and nuclear markers were not fully congruent. The spatial genetic structure that was based on nSSRs was more homogenous, while the cpSSR-based pattern pointed at strong genetic structure along the Alps. Five populations from the Central Alps had a combination of local and unique cpSSR clusters and admixture of those occurring in the Western and Eastern Alps. These findings may indicate the local survival of small populations of S. serpillifolia that were subsequently populated by new colonists in the postglacial period.

Plants growing along steep elevational gradients experience variations in abiotic conditions. The elevational gradient also affects the diversity and abundance of pollinators associated with these plants. As a result, plants may have locally adapted floral traits. However, detailed assessments of multiple floral traits along elevational gradients are often neglected despite the traits being important for plant sexual reproduction. We tested the association of floral traits with pollinators in response to elevation by identifying pollinators and measuring morphological and biochemical floral traits as well as studying the breeding systems of ten aggregated Rhododendron species in the Sikkim Himalaya. Corolla length, nectar volume and distance between stamen and stigma significantly decreased with elevation. In contrast, nectar concentrations were positively associated with elevation. Birds, bumblebees and flies were the three dominant pollinator groups. Bird visits showed a strong negative association with elevation while visits by bumblebees and flies increased with elevation. Species with longer corollas and higher nectar volumes showed higher rates of bird visits, while bumblebees were associated with species that had higher nectar concentrations. Fruit set following cross-pollination was high compared to self-pollination, and higher pollen limitation and auto-fertility were observed among species in higher elevations. These observed patterns in the association between floral traits and pollinator groups in response to elevation may help generate testable hypotheses on alpine plant–pollinator responses to climate warming.

The central Chilean Andes are located in a Mediterranean-type climate zone, characterized by dry summers and high irradiance. This creates a contrasting elevational gradient because higher elevations get more solid precipitation and lower temperatures, resulting in higher soil humidity along the growing season compared with severe drought at lower elevations. Therefore, species with wide elevational distributions, such as Phacelia secunda, must have developed specific adaptations to cope with contrasting severity of drought stress-induced photoinhibition at different elevations. We hypothesize that P. secunda from lower elevation, is more tolerant to drought stress-induced photo-damage than plants from high elevation. This higher tolerance will be associated to a higher diversity of photoprotective strategies in plants that naturally suffers severe drought every growing season. To test this hypothesis, plants from 2700 and 3600 m in the central Chilean Andes were grown under the common garden and then subjected to water restriction. We measured stress indicators, photochemistry of PSII and PSI and estimate alternative electron sinks. Drought affected P. secunda photosynthetic performance differentially depending on the elevation of provenance. Plants from lower elevation exhibited higher drought tolerance than higher elevation ones. This was related to higher levels of heat dissipation and alternative electron sinks exhibited by plants from lower elevation under drought stress. We concluded that plants naturally subjected to recurrent drought are better adapted to respond to drought stress using additional photochemical photoprotective mechanisms and confirm the role of alternative electron sinks ameliorating photodamage.