Alpine Plant Research Articles

Early signals of climate change impacts on alpine plant diversity in Indian Himalaya

Early signals of climate change impacts on alpine plant diversity in Indian Himalaya

Foliar flavonoids across an elevation gradient: Plasticity in response to UV, and links with floral pigmentation patterning

Metabolites produced in the flavonoid biosynthetic pathway (FBP) mitigate abiotic stress caused by factors such as ultraviolet (UV) light. Testing whether constitutive flavonoid production or flavonoid plasticity differ between populations spanning ecological gradients can reveal whether geographic patterns are consistent with local adaptation. Abiotic induction of flavonoids can occur in leaves as well as flowers where flavonoids influence UV color patterns perceived by pollinators. Assessing how foliar flavonoids are associated with floral color phenotypes can shed light on how pleiotropy affects biochemical phenotypes across tissues. We exposed Argentina anserina (Rosaceae) plants from alpine and lower elevation populations to low and high levels of UV and measured foliar and petal flavonoid production using UHPLC coupled mass spectrometry. We associated foliar flavonoid abundance with petal flavonoid abundance, and the size of the UV absorbing petal area (‘UV bullseye’). We found that total foliar flavonoids increased in response to UV due to flavonol upregulation, but only one class of flavonols, fisetin, exhibited stronger plasticity in alpine populations. Alpine populations tended to increase the quercetin-kaempferol ratio more than low elevation populations when exposed to higher UV, a signature of photoprotection and radical scavenging. Relationships between foliar flavonoids and the floral UV bullseye differed between alpine and low elevation populations. Previous work showed kaempferol glycosides contributed to variation in UV bullseye size at high elevation, while non-kaempferols spanning multiple FBP branches were associated with bullseye size at low elevation. Here, we found that alpine plants with less foliar kaempferol and greater kaempferol allocation to petals than leaves had larger floral UV-bullseyes, suggesting that floral UV patterning may be shaped by a biochemical tradeoff between tissues. Overall, nuanced elevational differences in flavonoid plasticity revealed by detailed metabolite classification provided support for local adaptation. Additionally, our study highlights that flavonoid production in leaves could influence the evolution of flavonoid-based floral phenotypes.

Phylogeography of Pleurospermum foetens (Apiaceae) From the Sky Islands of Southwest China.

Sky islands provide insights on how glacial-interglacial cycles have shaped species distribution and help for predicting species' responses to climate warming. The alpine subnival belt of southwest China, especially in the Hengduan Mountains and adjacent areas, is sky island-like. Among them, the Yunnan-Kweichow Plateau harbors several isolated mountains with well-developed alpine subnival vegetation, sharing a similar species composition with the Hengduan Mountains. However, the relationship between the sky islands of the Hengduan Mountains and the Yunnan-Kweichow Plateau remains insufficiently explored. Pleurospermum foetens (Apiaceae) is a species endemic to the alpine screes of the Yunnan-Kweichow Plateau and the Hengduan Mountains. We used DNA sequence data from 59 individuals across 9 populations, combined with ecological niche modeling, to investigate the evolution history and future distribution of P. foetens within this sky island region. The results indicate the following: (1) P. foetens exhibits a significant phylogeographic structure and can be classified into three nrDNA clades and two cpDNA clades, respectively, (2) a nuclear-plastid discordance observed in P. foetens and its relatives based on phylogenetic analysis. P. foetens is monophyletic in the nrDNA phylogeny, while two major clades (HDM and YGP) are present in the cpDNA phylogeny, each forming a clade with other congeneric species. (3) Ecological niche modeling of P. foetens indicated that the species had the most extensive suitable habitat during the last glacial maximum (LGM). However, anticipated climate warming in the coming decades is expected to reduce the suitable range of P. foetens, posing a significant threat to isolated marginal populations (e.g., Shizi Mountain) with restricted alpine scree habitats. In conclusion, our study highlights the substantial effect of sky island and glacial-interglacial cycles on the population divergence of P. foetens. Conservation efforts for marginal populations of alpine plants in the Yunnan-Kweichow Plateau require increased attention and prioritization.

Genome-wide identification of a MADS-box transcription factor family and their expression during floral development in Coptis teeta wall

BackgroundMADS-box transcription factors have been shown to be involved in multiple developmental processes, including the regulation of floral organ formation and pollen maturation. However, the role of the MADS-box gene family in floral development of the alpine plant species Coptis teeta Wall, which is widely used in Traditional Chinese Medicine (TCM), is unknown.ResultsSixty-six MADS-box genes were identified in the C. teeta genome. These genes were shown to be unevenly distributed throughout the genome of C. teeta. The majority of which (49) were classified as type I MADS-box genes and were further subdivided into four groups (Mα, Mβ, Mγ and Mδ). The remainder were identified as belonging to the type II MADS-box gene category. It was observed that four pairs of segmental and tandem duplication had occurred in the C. teeta MADS-box gene family, and that the ratios of Ka/Ks were less than 1, suggesting that these genes may have experienced purifying selection during evolution. Gene expression profiling analysis revealed that 38 MADS-box genes displayed differential expression patterns between the M and F floral phenotypes. Sixteen of these MADS-box genes were further verified by RT-qPCR. The 3D structure of each subfamily gene was predicted, further indicating that MADS-box genes of the same type possess structural similarities to the known template.ConclusionsThese data provide new insights into the molecular mechanism of dichogamy and herkogamy formation in C. teeta and establish a solid foundation for future studies of the MADS-box genes family in this medicinal plant species.

Temporal variability and predictability predict alpine plant community composition and distribution patterns.

One of the most reliable features of natural systems is that they change through time. Theory predicts that temporally fluctuating conditions shape community composition, species distribution patterns, and life history variation, yet features of temporal variability are rarely incorporated into studies of species-environment associations. In this study, we evaluated how two components of temporal environmental variation-variability and predictability-impact plant community composition and species distribution patterns in the alpine tundra of the Southern Rocky Mountains in Colorado (USA). Using the Sensor Network Array at the Niwot Ridge Long-Term Ecological Research site, we used in situ, high-resolution temporal measurements of soil moisture and temperature from 13 locations ("nodes") distributed throughout an alpine catchment to characterize the annual mean, variability, and predictability in these variables in each of four consecutive years. We combined these data with annual vegetation surveys at each node to evaluate whether variability over short (within-day) and seasonal (2- to 4-month) timescales could predict patterns in plant community composition, species distributions, and species abundances better than models that considered average annual conditions alone. We found that metrics for variability and predictability in soil moisture and soil temperature, at both daily and seasonal timescales, improved our ability to explain spatial variation in alpine plant community composition. Daily variability in soil moisture and temperature, along with seasonal predictability in soil moisture, was particularly important in predicting community composition and species occurrences. These results indicate that the magnitude and patterns of fluctuations in soil moisture and temperature are important predictors of community composition and plant distribution patterns in alpine plant communities. More broadly, these results highlight that components of temporal change provide important niche axes that can partition species with different growth and life history strategies along environmental gradients in heterogeneous landscapes.

Mitochondrial Genome Assembly and Structural Characteristics Analysis of Gentiana rigescens.

Gentiana rigescens, an alpine plant with significant medicinal value, possesses a complex genetic background. However, comprehensive genomic research on G. rigescens is still lacking, particularly concerning its organelle genome. In this study, G. rigescens was studied to sequence the mitochondrial genome (mitogenome) and ascertain the assembly, informational content, and developmental expression of the mitogenome. The mitogenome of G. rigescens was 393,595 bp in length and comprised four circular chromosomes ranging in size from 6646 bp to 362,358 bp. The GC content was 43.73%. The mitogenome featured 30 distinct protein-coding genes, 26 tRNA genes, and 3 rRNA genes. The mitogenome of G. rigescens also revealed 70 SSRs, which were mostly tetra-nucleotides. In addition, 48 homologous fragments were found between the mitogenome and the chloroplast genome, with the longest measuring 23,330 bp. The documentation of the mitochondrial genome of G. rigescens is instrumental in advancing the understanding of its physiological development. Decoding the G. rigescens mitogenome will offer valuable genetic material for phylogenetic research on Gentianaceae and enhance the use of species germplasm resources.

Persistence Over Millennia Through Extreme Clonal Longevity: Phylogenomic Insight Into History of One of the World's Rarest Plant Species

ABSTRACTAimThe evolutionary history of European alpine plant species with medium to large geographical ranges is relatively well explored. Here, we investigate the genetic structure and diversity of an extremely narrow endemic and one of the world's rarest plants.LocationEastern Carpathians, Romania.TaxonAndryala laevitomentosa (Asteraceae), an evolutionarily isolated herb species with a worldwide range limited to five micropopulations distributed along a 1.8 km long mountain ridge.MethodsWe used three plastid loci, nuclear ribosomal ITS and genome‐wide, mostly nuclear 26,272 Single‐Nucleotide Polymorphism (SNPs) obtained from RAD‐seq data. We assessed haplotype and genotype diversity, dated the resulting phylogeographic structure, quantified seed production and inferred vegetative propagation.ResultsMaternally inherited plastid markers and nuclear genomic data revealed a concordant pattern: (i) limited genetic diversity, with seven cpDNA haplotypes and 11 RAD‐seq multilocus genotypes; (ii) a strong geographic structure corresponding to spatially isolated genets (clones). The species is likely of early Pleistocene origin (c. 2 Mya), and the estimated age of individual clones varied from c. 24 to 64 Kya. The average seed set assessed over 3 years was only 0.4%. However, the species reproduces veg by axillary and adventitious rosettes formed on rhizomes and roots, respectively.Main ConclusionsThe strong trade‐off between sexual and vegetative reproduction explains not only a deep and ancient phylogeographic structure but also the rarity of the species. Its survival depends almost entirely on vegetative reproduction. The genets of A. laevitomentosa are amongst the oldest clones ever documented in angiosperms. The persistence of these clones in situ for tens of thousands of years suggests an exceptional ability of this species to adapt to major climatic oscillations throughout the Pleistocene and Holocene and challenge our perception of the extent of resilience in plants.

The third dimension of alpine plant leaf traits is related to cold-tolerance

Alpine plants possess unique traits to adapt alpine environments. Whether leaf trait relationships of alpine plants can be captured by the two trait dimensions of organ size and resource economics is unknown. We hypothesized that, beyond the trait dimensions of leaf size and resource economics, non-structured carbohydrates (NSC) would reflect a dimension of cold-tolerance in alpine plants. To test this hypothesis, we measured 12 leaf traits critical to leaf construction and growth in 143 species across 7 sites ranging from alpine steppes to alpine meadows along an environmental gradient on the Tibetan Plateau. Furthermore, a cold resistance experiment was conducted at one of these sites to estimate the lethal temperature causing 50% frost damage (LT50) of 11 alpine species. The majority of variations in 12 leaf traits of alpine plants were captured by three trait axes, in which leaf carbon (LCC) and NSC (including starch, LSC and soluble sugars, LSS) were clustered in a new dimension (PC3) beyond leaf size and structure, and resource economics. Although LCC, LSC and LSS all showed negative correlations with MAT, a significant negative correlation was only found between LSS and LT50. It indicated that PC3 was able to reflect the cold-tolerance of alpine plants to some extent, in which LSS was the most critical trait. The storage and transformation of NSC under stressful conditions could reflect a dimension of long-term metabolic adaptation and cold-tolerance, which is an extension of the resource-utilization strategy beyond construction cost and growth.

Long-Term Alpine Plant Responses to Global Change Drivers Depend on Functional Traits.

Forecasting plant responses under global change is a critical but challenging endeavour. Despite seemingly idiosyncratic responses of species to global change, greater generalisation of 'winners' and 'losers' may emerge from considering how species functional traits influence responses and how these responses scale to the community level. Here, we synthesised six long-term global change experiments combined with locally measured functional traits. We quantified the change in abundance and probability of establishment through time for 70 alpine plant species and then assessed if leaf and stature traits were predictive of species and community responses across nitrogen addition, snow addition and warming treatments. Overall, we found that plants with more resource-acquisitive trait strategies increased in abundance but each global change factor was related to different functional strategies. Nitrogen addition favoured species with lower leaf nitrogen, snow addition favoured species with cheaply constructed leaves and warming showed few consistent trends. Community-weighted mean changes in trait values in response to nitrogen addition, snow addition and warming were often different from species-specific trait effects on abundance and establishment, reflecting in part the responses and traits of dominant species. Together, these results highlight that the effects of traits can differ by scale and response of interest.

Early Life History Divergence Mediates Elevational Adaptation in a Perennial Alpine Plant

ABSTRACTSpatially divergent natural selection can drive adaptation to contrasting environments and thus the evolution of ecotypes. In perennial plants, selection shapes life history traits by acting on subsequent life stages, each contributing to fitness. While evidence of adaptation in perennial plants is common, the expression of life history traits is rarely characterized, limiting our understanding of their role in adaptive evolution. We conducted a multi‐year reciprocal transplant experiment with seedlings from low and high elevation populations of the alpine carnation Dianthus carthusianorum to test for adaptation linked to contrasting climates and inferred specific contributions of early life stages to fitness. We assessed genotype by environment interactions in single fitness components, applied matrix population models to achieve an integrated estimate of fitness through population growth rates, and performed trade‐off analyses to investigate the advantage of alternate life history traits across environments. We found evidence of genotype by environment interactions consistent with elevational adaptation at multiple stages of the early life cycle. Estimates of population growth rates corroborated a strong advantage of the local genotype. Early reproduction and survival are alternate major contributors to adaptation at low and high elevation, respectively, and are linked by trade‐offs that underlie the evolution of divergent life history traits across environments. While these traits have a strong genetic basis, foreign populations express co‐gradient plasticity, reflecting the adaptive strategy of the local populations. Our study reveals that selection associated to climate has driven the evolution of divergent life histories and the formation of elevational ecotypes. While the high energy environment and strong competition favor investment in early reproduction at low elevation, limiting resources favor a more conservative strategy relying on self‐maintenance at high elevation. The co‐gradient plasticity expressed by high‐elevation populations may facilitate their persistence under warming climatic conditions.

Effect of Climate Change on Alpine Flowers

Global warming results in climate change that increases the intensity of rainfall, drought, dry spell, heat waves. This condition have profound impact on alpine plant ecology and induce migration or range shifts of spe¬cies in search for their optimal growth conditions. These shifts subsequently lead to change in local species composition, often resulting in a relative increase of warm demanding species and a decreasing number of cold demanding species. The result of this change may cause habitat loss and disastrous extinction in those alpine environments. An alpine flower has been serving as source of genetic material for ornamental flower industry. Improvement of commercial cultivars through interspecific hybridization with wild relatives has also been the major way forward for transfer of important traits such as disease resistance. However, as a result of global warming, heat stress has become the major challenge for alpine ecosystem that is estimated to be 3% of terrestrial habitats. Here, I review literature regarding impacts of climate change on alpine flowers by using specific commercially important flowers as an example: <i>Dianthus</i>, <i>Primula</i> and <i>Rhododendron</i>. Then, I discuss ways to enhance <i>Rhododendron</i> breeding efficiency for heat stress using invitro growth conditions. Finally, I summarize with indicating future areas of research that should be undertaken.

Altitude-Dependent Morphophysiological, Anatomical, and Metabolomic Adaptations in Rhodiola linearifolia Boriss.

Rhodiola linearifolia Boriss., a perennial alpine plant from the Crassulaceae family, is renowned for its unique medicinal properties. However, existing research on this species is limited, particularly regarding the impact of altitude on its physiological and medicinal compounds. The current study employed morphophysiological and anatomical methods to explore the adaptive mechanisms of R. linearifolia across different altitudinal gradients, while also examining photosynthetic pigments and metabolomic changes. Our results indicate that despite the simultaneous effects of various mountain abiotic factors, significant correlations can be identified between altitude and trait variation. An optimal growth altitude of 2687 m above sea level was identified, which is pivotal for sustainable ecosystem management and potential species introduction strategies. It is noted that increasing altitude stress enhances the synthesis of secondary antioxidant metabolites in R. linearifolia, enhancing its pharmaceutical potential.

Hydroclimatic change and vegetation response in Tropical African alpine environments over the Holocene

Future precipitation is highly uncertain, particularly in East Africa where model projections contradict modern observational trends. Climate changes in East Africa's mountains are even less well understood, yet these mountains are threatened by warming, extreme flooding, fires, and the rapid disappearance of glaciers. Paleoclimatic and paleoenvironmental records can contextualize ongoing and future changes; however, proxy records from East African mountains disagree with each other and, in some cases, differ from nearby lowland sites. It is unclear if these discrepancies are due to geographic or altitudinal gradients in climate or processes that impact the fidelity of climate proxies in these mountains. To better understand past mountain precipitation and vegetation change, we produced three new records of the hydrogen and carbon isotopic composition of terrestrial leaf waxes (δ2Hwax and δ13Cwax) spanning the Holocene using lake sediment cores collected from Lake Mahoma (2990 m asl), Lake Africa (3895 m asl), and Lake Kopello (4017 m asl) in the Rwenzori Mountains, Uganda-Democratic Republic of Congo. We find similar trends at all three sites in reconstructed precipitation hydrogen isotopic composition (δ2Hprecip), which we interpret to reflect precipitation amount. Our records show drying occurred during the Younger Dryas (∼12 cal ka BP), enhanced precipitation during the African Humid Period (∼10-5 cal ka BP) and drying in the mid to late Holocene (∼5-0 cal ka BP), similar to adjacent lowland sites. We observe a gradual termination of the African Humid Period in the Rwenzori, consistent with many regional records. We also observe distinct patterns of Holocene precipitation change in Eastern and Western Africa, indicating differences in the delivery of moisture from the Atlantic and Indian Oceans. Despite changes in precipitation over the Holocene, the carbon isotopic composition of the waxes in Rwenzori lakes indicates constant C3 vegetation and eco-hydrological stability, in contrast to sites from lower elevations. This likely indicates climate remained humid and cool enough throughout the Holocene to maintain forest and alpine plant communities at these high-elevation mountain sites.

Spatial-Temporal Analysis of the Effects of Frost and Temperature on Vegetation in the Third Pole Based on Remote Sensing

Frost events during the growing season can significantly impact vegetation function and structure. Solar-induced chlorophyll fluorescence (SIF) and the normalized difference vegetation index (NDVI) are two widely used proxies for measuring vegetation growth. However, the extent to which NDVI and SIF respond to frost events and how the responses vary under different temperature, precipitation, and shortwave radiation conditions are still unclear. In this study, spatially gridded meteorological data were employed to identify frost events during the growing season in the Third Pole. Subsequently, vegetation responses to the frost events were examined using remotely sensed SIF and NDVI data in different seasons in the Third Pole. During the growing season, the number of frost events declined faster from 2001 to 2009 than from 2010 to 2018. From 2001 to 2009, most alpine vegetation areas in the Third Pole exhibited greening trends. SIF exhibited a strong correlation with environmental factors and showed higher sensitivity to environmental factors compared to the NDVI. Over the past two decades, the impact of temperature and frost days on alpine vegetation has decreased while the impact of precipitation and radiation has increased. This suggests that the control mechanisms governing alpine vegetation are gradually shifting in response to ongoing climate change in the Third Pole. This study enhances our comprehension of frost changes in alpine regions during the growing season and enriches our understanding of how alpine vegetation responds to climate change.

Reproductive Performance of the Alpine Plant Species Ranunculus kuepferi in a Climatic Elevation Gradient: Apomictic Tetraploids Do Not Show a General Fitness Advantage over Sexual Diploids.

Previous studies on the mountain plant Ranunculus kuepferi concluded that apomictic self-compatible tetraploids have experienced a niche shift toward a colder climate during the Holocene, which suggests a fitness advantage over the sexual, self-sterile diploid parents under cold and stressful high-mountain conditions. However, there is still a lack of information on whether reproductive development would be advantageous for tetraploids. Here, we report on microsporogenesis, megagametogenesis, the dynamics of flower and seed development, and the consequences for reproductive success in a common garden experiment along a 1000 m climatic elevation gradient and in natural populations. Flower buds were initiated in the year preceding anthesis and passed winter in a pre-meiotic stage. Flower morphology differed in the known cytotype-specific way in that tetraploid flowers produced about twice as many carpels and fewer petals, stamens, and pollen grains than diploid flowers. Tetraploids developed precociously aposporous embryo sacs and showed a high rate of developmental disturbances. Sexual seed formation prevailed in diploids and pseudogamous apomixis in tetraploids. Along the elevation gradient, stigma pollen load, pollen performance, and seed output decreased. Combinations of reproductive traits, namely, bypass of meiosis irregularities and uniparental reproduction, might have promoted the vast expansion of apomictic R. kuepferi lines across the European Alps.

Nocturnal moth pollination in an alpine orchid, Platanthera tipuloides

AbstractPollination success of alpine plants is often restricted by low and unpredictable pollinator activity because of harsh and unstable weather conditions, where nocturnal pollination is rare. The alpine orchid, Platanthera tipuloides (Orchidaceae), has inconspicuous greenish yellow flowers with a sweet scent and a long spur that contains nectar. These floral traits are expected to be related to nocturnal moth pollination. To elucidate the pollination mode and reproductive characteristics of this species, we measured floral traits (spur length, nectar content in the spur, floral scent), documented flower visitors using camera traps, and quantified self‐compatibility and the degree of pollen limitation through controlled pollinations at two study plots in the Taisetsu Mountains, northern Japan. It was revealed that P. tipuloides is self‐incompatible and pollen limitation was absent at one of the study plots. The flowers emitted more volatile substances during the night, including lilac aldehyde isomers, which are known to attract moths. A nocturnal moth, Entephria amplicosta, was observed foraging nectar from the flowers, while no diurnal visitors were observed. The proboscis of E. amplicosta was shorter than the spur length, but it was long enough to access the accumulated nectar in the spurs. These results suggest that nocturnal pollination by moths is possible and can be efficient even in an alpine ecosystem with harsh environmental conditions.

Shifting alpine plant distributions with global change: Testing the environmental matching hypothesis

ABSTRACT Species facing novel temperature, precipitation, and nitrogen (N) deposition regimes must move or adapt to persist. For long-lived plants, a primary form of climate acclimation is through shifting geographic range limits or establishing in favorable microclimates. One commonly assumed but rarely tested hypothesis is that these shifts can be predicted by environmental matching: that the environmental characteristics that define a current distribution should predict how a population will shift with environmental changes. To test this hypothesis, we transplanted four alpine and two subalpine plant species into environments with experimentally increased temperature, snow, and N. We predicted that species would perform best when environmental change matched their geographic distributional characteristics: increased temperature, snow, and N (two subalpine species), increased temperature (two dry meadow specialists), and increased snow (two snowbed specialists). Our results provided limited support for the environmental matching hypothesis. Snowbed specialists did not benefit from increased snow, dry meadow specialists' performance did not consistently differ among the treatments, and subalpine plants' survival was not affected by treatments while their growth response was variable among species. Our results suggest that global change effects will vary among species and distributional shifts are not easily predicted by species environmental preference.

Exploring botanical varieties in alpine landscape of Himalayas: A study of vegetation and species composition in Madhmaheshwar Valley, Western Himalaya, India

Alpine meadows emerged as the hallmark vegetation type, embodying the essence of botanical richness. In this research endeavor, the focus was on exploring the intricate tapestry of alpine flora nestled within the Madhmaheshwar Valley, spanning elevations ranging from 3200 to 4950 meters above sea level. This comprehensive study yielded a trove of botanical insights, documenting an impressive assemblage of 462 distinct plant species. These species were carefully cataloged across 237 genera, encompassing a rich diversity represented by 61 distinct families. In the study area, the family Asteraceae was the dominant family with 58 species and 30 genera followed by Rosaceae with 33 species and 16 genera, and Ranunculaceae with 27 species across 15 genera. Among the genera Carex L., with 10 species, was the dominant, followed by Saxifraga Tourn. ex L., Gentiana Tourn. ex L., Pedicularis L., and Primula L. followed closely behind with nine species each. Additionally, Rhodiola L., Bistorta (L.) Scop., and Epilobium Dill. ex L. displayed their vitality with seven species each. The study used meticulous research methodology to categorize forest types based on floral diversity and altitude distribution. Rigorous verification processes ensured the reliability of findings, with specimens identified using up-to-date references and cross-referenced with authentic herbarium samples. Fieldwork occurred between early May and late October, aligning with seasonal accessibility due to heavy snowfall the rest of the year. Alpine meadows and scrubs dominated the study area, highlighting their resilience. Alpine plants showcased various adaptive morphologies, such as cushion-forming and mat-forming structures, with thick cuticles defending against desiccation. Despite harsh conditions, these plants displayed modified structures enabling growth and blossoming. Many were highly specialized, emphasizing unique adaptations to their habitats.

Predicting the potential habitat suitability of Saussurea species in China under future climate scenarios using the optimized Maximum Entropy (MaxEnt) model

The Saussurea species, renowned for its biodiversity and medicinal significance in high-elevation regions, faces endangerment due to climate change and human activities. Despite this, conservation research on Saussurea has been limited. To fill the knowledge gap, this study employed the optimized MaxEnt model to simulate Saussurea's habitat suitability and analyze key environmental factors influencing its distribution. Additionally, considering the sensitivity of Saussurea habitats to climate change, this research also simulated the changes in suitable habitat and distribution centroid shifts of Saussurea under different climate scenarios (SSP126, SSP245, SSP370, and SSP585) for the periods 2040s, 2060s, 2080s and 2100s. Findings indicated that Saussurea's suitable habitat was primarily located in the Qinghai-Tibet Plateau, notably within the Himalayas and Hengduan Mountains. The areas of extremely and moderately suitable habitats were 1.106 × 10⁵ km2 and 3.436 × 10⁵ km2, respectively. Elevation, Isothermality (Bio3), and Temperature Annual Range (Bio7) were identified as the main environmental factors. Future projections suggest severe habitat fragmentation and a decrease in suitable habitat areas. By 2100, the total area of suitable Saussurea habitat will decrease under the SSP126, SSP245, SSP370, and SSP585 scenarios to 8.658 × 10⁵ km2, 6.971 × 10⁵ km2, 5.811 × 10⁵ km2, and 5.979 × 10⁵ km2, respectively. Additionally, a slight southeastward shift in the distribution centroid was observed. This study is expected to provide guidance for the conservation of Saussurea and alpine plant biodiversity.

Geographic distribution and impacts of climate change on the suitable habitats of two alpine Rhododendron in Southwest China

Mountains of Southwest China (MSC) serve as a prominent geographical distribution center for Rhododendron delavayi and Rhododendron irroratum (Ericaceae). These mountains are currently experiencing an unparalleled warming trend, which poses severe challenges to the survival of these keystone alpine Rhododendron species. However, the geographical distribution responses of these species to climate change remain incompletely understood and are often overlooked. Here, we constructed ensemble models (EMs) using ten models of five algorithms to calibrate ecological niche models and predict suitable habitat areas for the two Rhododendron species across four climate emission scenarios over three distinct periods. Our analysis indicated the higher importance of elevation than temperature and precipitation in shaping the spatial distribution of the two alpine Rhododendron species. The current suitable habitats of R. delavayi and R. irroratum have areas spanning 14.85 × 104 and 11.01 × 104 km2, respectively, which are mostly distributed in the western and central regions of MSC. The suitable habitat of R. delavayi is projected to decrease by 15.09–75.31 %, but the potential habitat of R. irroratum is expected to shrink by12.71 % to 76.8 % in different future climate scenarios. The suitable habitats of these species may become confined in a “summit trap” within relatively low-altitude regions, whereas habitats distributed at high altitudes may serve as “biological refuges.” The future distribution of the two alpine Rhododendron species will shift to high altitudes in westward and northward regions, with substantial thermal and hydrothermal changes as the primary drivers of habitat alteration and migration patterns. The losses or benefits for species under climate warming depend on their ecological niches and geographical location, which provide a geographical guidance for the long-term conservation and sustainable use of species and essential insights into the spatial conservation assessment of alpine plant groups in biodiversity hotspots in the future.