Alpine Botany最新文献

We describe the distribution and diversity of vascular plants at high elevations (3980–4570 m above sea level) in the Rwenzori Mountains and Mount Elgon National Parks in Uganda. These were the first target regions of the “Global Observation Research Initiative in Alpine Environments” (“GLORIA”) on the African continent. In each target region, four summits spanning elevations from the treeline ecotone up to the limits of vascular plant life were selected and assessed in July and August 2011 using the standardised GLORIA protocol. Few vascular plant species were present on high elevation summits, particularly in Rwenzori, where many sub-plots had little or no vascular plant cover. Observations from Rwenzori include 26 vascular plant species, and from Mount Elgon 47, of which 10 and 15 species, respectively, were endemic. In contrast, non-vascular plant cover greatly increased with elevation. The lowest sites showed considerable diversity and were floristically dissimilar to the highest summits. Subsequent resurveys, repeating the GLORIA protocol, will be critical in the assessment of ongoing dynamics and change.

In their recent article in Alpine Botany (133:63-67, 2023a), Körner et al. revisit the outcome of an interesting experiment from 2009 (Lenz et al., Plant Ecolog Divers 6:365–375, 2013). Although I appreciate the new focus on cell wall lignification, I disagree with their main conclusion. Rather than questioning the role cold temperatures play in cell wall lignification, the authors provide experimental evidence for a thermal threshold under which the secondary cell walls of mountain pines (Pinus uncinata) at the upper treeline in the Swiss Alps exhibit a reduced lignin content.

Campos de altitude are high-altitude grasslands found in the mountain ranges of southeastern and southern Brazil, which are characterized by high species richness and endemism. Because of the difficulty in delimiting this vegetation type, measuring biodiversity patterns is challenging. Here, we compared the application of two methods using spatial data to estimate angiosperm diversity in campos de altitude: (1) filtering occurrence data by elevation, canopy height, location and keywords and; (2) the same as the first, however, adding a filter of “campos de altitude” in the vegetation type of the Flora e Funga do Brasil database. Also, we discuss conservation status, plant collections, endemism, vegetation data and similarity among 14 sites harboring campos de altitude. Our two resulting lists indicated between 1087 and 2398 angiosperm species and infraspecific taxa in campos de altitude, mostly belonging to Asteraceae and Poaceae and endemic to Brazil. Extrapolations of species richness suggest a potential number of up to 4000 species. Of the taxa assessed for conservation status, 53–65% are threatened or near threatened. The flora of campos de altitude is more similar on closely located mountains rather than on mountains with similar geological characteristics and origin. We provide an editable list online destined to seek help from taxonomists to generate a more accurate species list, to support advances in knowledge on this unique tropical montane ecosystem.

Although the Balkan Peninsula belongs to the most mountainous regions of Europe, phylogeographic structure of its alpine flora remains insufficiently understood, especially for species distributed both in the western and eastern parts of the Peninsula. We analyzed Campanula orbelica, a Balkan endemic typical of high-mountain siliceous grasslands, based on the population genetic structure, climatic niche modeling at the species- and intraspecific level, and niche hindcasting back to the Last Glacial Maximum (LGM; 20 kya). Our data reveal a clear phylogeographic pattern with three geographically coherent genetic groups: (i) the most divergent and spatially restricted lineage of the Pirin mountains (east), (ii) neighboring Rila mountains and other eastern Balkan massifs (Rhodopes, Stara Planina, Vitoša), and (iii) the most geographically disjunct mountains of the Scardo-Pindhic range (Šar Planina and Korab) in the west. This pattern indicates multiple refugia and isolated evolutionary centers within the Balkan Peninsula mountains, with the eastern part of the range as likely ancestral area, and an early dispersion into the western region, which formed the main geographical disjunction. The genetic divergence was only partly correlated with geographical isolation, clear dispersal barriers, or climatic niche shifts, suggesting contrasting isolation/dispersal dynamics in various parts of the range. Climatic niche overlap was low among eastern vs. western groups, which correlates with the longest spatial distance and significant genetic divergence, while niche characteristic of the Pirin lineage was a subset of the adjacent Rila lineage niche. High genetic divergence of the Pirin populations was also not correlated with persistent gaps in potential distributions but hypothetically may have been triggered by diversified (limestone/silicate) bedrock conditions. Our results highlight the need for high-mountain phylogeographic surveys in the eastern part of the Balkan Peninsula, to assess the biogeographical relevance of isolation patterns and definition of evolutionarily important units in the high-mountain flora.

The growing evidence for the role of introgression in evolution is challenging for species delimitation, taxonomy, and conservation. Here, we examine the isolation of Saxifraga delphinensis, a south-west alpine narrow endemic, from its sympatric congeners Saxifraga exarata and Saxifraga moschata. Our analyses, based on morphological, molecular and genome-wide data, were extended to taxa from Jura, Massif Central, north-east Iberian mountains and Pyrenees to broaden the phylogenetic scope of the study. Phylogenetic results support the close relationship between (i) S. delphinensis, Saxifraga cebennensis and one population of S. exarata from Queyras and (ii) between S. lamottei, S. giziana and S. moschata. Saxifraga exarata, which was extensively sampled, is composed of several clades and is paraphyletic to other taxa. While morphological and genetic data support the evolutionary distinctiveness of S. delphinensis, introgression with S. exarata is shown by various data and analyses. In addition, ABBA-BABA analyses and plastome phylogeny reveal a possible contribution of the north-east Iberian endemic Saxifraga vayredana into the history of S. delphinensis. Overall, the results show a complex evolutionary history with frequent hybridization and spanning several mountain ranges in Europe.

In the Bale Mountains, the ericaceous belt ranges between 3200 and 3800 m asl. Studies indicate an expansion on the Sanetti Plateau at the end of the Late Glacial and during the early Holocene. Currently, only patches of Erica growing between boulders are found on the Plateau, while most of the landscape above 3800 m asl is covered by afro-alpine plants. Driving factors for Erica patches above the upper ericaceous ecotone is a matter of debate. This study evaluates site variables and biogeochemical properties of soils under Erica patches and nearby Erica-free control to understand the environmental conditions responsible for the patchy occurrence of Erica on the Sanetti Plateau. Except for the boulder richness, Erica and control plots have comparable topography, soil texture, and electrical conductivity. However, soils below Erica patches have higher total organic carbon, nitrogen, carbon-to-nitrogen ratios, and black carbon contents than the control plots indicating fresh organic matter input and availability of combustible fuel. This implies that Erica did not fully cover the control plots in former times. Carbon and nitrogen stocks were slightly higher in control plots due to the lower stone contents of the profiles. In addition, soils of the Erica plots showed more positive δ¹³C values than the control soils, possibly attributed to water stress. In general, the relief and soil conditions of control plots may support the growth of Erica. However, Erica growing between boulders seems to benefit from the favorable microclimate and physical protection against grazing and fire.

Mountains represent ‘experiments by nature’ that permit testing ecological theory. Using herbarium samples of 92 Rhododendron species collected between 800 and 4500 m a.sl. in the Himalaya-Hengduan Mountains region, SW China, we explored congeneric elevational trends in key plant traits at the among- and at the within-species level. We aimed at identifying the contributing factors to phenotypic trait expression across a climatic gradient, distinguishing effects in response to elevation from those due to phylogenetic relatedness, non-phylogenetic species effect, and within-species trait variability. We found that a substantial fraction of the trait variation (up to 88%) is deeply rooted in phylogeny, with species elevation also revealing a strong phylogenetic signal. While accounting for these phylogenetic influences, we still found consistent associations with elevation of anatomical (increasing leaf thickness and decreasing specific leaf area), morphological (decreasing plant and leaf size, annual length increment), physiological (less negative foliage δ¹³C signal), and reproductive traits (flower size largely conserved, while leaf size declines, hence relative investment in flowers increases). Our findings support a combined action of phylogenetic inertia and phenotypic adjustments of plants to life conditions at high elevation. Given that our samples come from one genus and a natural climatic gradient (rather than botanical gardens) with temperature the dominant variable, such patterns represent a robust and representative signature of the multiple causes of trait-environment associations in woody species.

In their 2013 paper, Lenz et al. illustrated how trees growing at the low-temperature limit respond to a chronic in situ warming or cooling by 3 K, by employing Peltier-thermostated branch collars that tracked ambient temperatures. The micro-coring-based analysis of seasonal tree ring formation included double-staining microtome cross sections for lignification, but these data had not been included in the publication. In this short communication, we complement these data, collected in 2009 at the Swiss treeline, and we show that a 3 K cooling that corresponds to a 500–600 m higher elevation, had no influence on lignification. However, when a frost event occurred during the early part of ring formation, the 3 K cooling produced a blue (non-lignified) layer of cells, followed by normally lignified cells for the rest of the season. Hence, the event did not affect the cambium, but interrupted cell wall maturation in cells that were in a critical developmental stage. We conclude, that chronic cooling does not affect lignification at treeline, but it increases the risk of frost damage in premature xylem tissue.

Here, we quantified the dieback of Silene acaulis subsp. bryoides along a 500 m elevational transect from 1900 to 2400 m a.s.l. in the Sibillini Group (Apennines). We also investigated the role of the 2022 summer heat wave that affected the Apennines as a putative cause. The intensity of the dieback was not uniformly distributed across the elevational gradient, but was widespread at 1900 and 2000 m a.s.l. and decreased with increasing elevation. Specifically, 40.7% and 38.4% of plants were affected by dieback at 1900 and 2000 m a.s.l., respectively, but less than 1% at elevations above 2300 m a.s.l. Regarding climate, the maximum air temperature in 2022 was 3.7, 4.5, and 3.4 °C above the respective long-term average in May, June, and July. A similar trend was observed for the minimum temperature. The monthly maximum (21.5 °C) and minimum (14.6 °C) temperatures in July were the highest ever recorded since the monitoring station was commissioned in 2005. In terms of daily maximum temperatures, three consecutive days with temperatures above 25 °C were recorded in July 2022, an upper limit that has only been reached on four days in the last 17 years. Regarding precipitation, 180 mm of precipitation fell during the May–August growing season compared to the long-term average of 255 mm, a decrease of 30%. More importantly, only 15.2 mm of rain fell in July 2022, compared to a long-term average of 54.3 mm. The sudden dieback of Silene highlights the vulnerability of high elevation vegetation to climate change. Moreover, the loss of Silene cushions is alarming for the survival of the species, which is long lived but very slow growing.

The major response of organisms to the climatic oscillations of the Quaternary was migration. Considering alpine plants, migration into low elevation cold-stage refugia took place in glacial periods, and re-migration into high elevation areas in interglacial periods and the Holocene. The present review examines the possibility that populations at the rear edge of re-migrating species persisted and evolved in the area of cold-stage refugia. Here, they would be faced with increasingly warm conditions and strong competition from other species re-migrating into the cold-stage refugial area. For the flora of the European Alps, I identified 13 species or subspecies pairs in which one taxon of a pair may represent an evolutionary derivative of persisting rear-edge populations, whereas the other represents populations which tracked their niche and re-migrated into high elevation areas. If confirmed by further analyses, these taxon pairs would illustrate that adaptive evolutionary divergence in Quaternary interglacials and the Holocene is possible, and most likely can persist through one or several much longer glacial periods.