Elevation Gradient Research Articles

Influences of elevational gradient on flower size and number of Gentiana lawrencei var. farreri.

Plants can adapt to environmental changes by adjusting their functional traits and biomass allocation. The size and number of flowers are functional traits related to plant reproduction. Life history theory predicts that there is a trade-off between flower size and number, and the trade-off can potentially explain the adaptability of plants. Elevation gradients in mountains provide a unique opportunity to test how plants will respond to climate change. In this study, we tried to better explain the adaptability of the alpine plant Gentiana lawrencei var. farreri in response to climate change. We measured the flower size and number, individual size, and reproductive allocation of G. lawrencei var. farreri during the flowering period along an elevation gradient from 3200 to 4000 m, and explored their relationships using linear mixed-effect models and the structural equation model. We found that with elevation increasing, individual size and flower number decreased and flower size increased, while reproductive allocation remained unchanged. Individual size positively affected flower number, but was not related to flower size; reproductive allocation positively affected flower size, but was not related to flower number; there is a clear trade-off between flower size and number. We also found that elevation decreased flower number indirectly via directly reducing individual size. In sum, this study suggests that G. lawrencei var. farreri can adapt to alpine environments by the synergies or trade-offs among individual size, reproductive allocation, flower size, and flower number. This study increases our understanding of the adaptation mechanisms of alpine plants to climate change in alpine environments.

Elevation differentially shapes functional diversity patterns in understorey forest communities when considering intraspecific and interspecific trait variability

AbstractQuestionsWhat is the relative importance of interspecific and intraspecific trait variation and their covariation in the herb layer of European temperate beech forests, and how do they vary with elevation? Is there evidence of interspecific trait convergence at higher elevations, as postulated by the habitat‐filtering hypothesis, and is this convergence enhanced or counteracted by intraspecific variation?LocationNational Park “Foreste Casentinesi, Monte Falterona and Campigna”, Italy.MethodsWe measured four functional traits – plant height, specific leaf area (SLA), leaf dry matter content (LDMC) and leaf area – across 775 individuals from 60 herb‐layer species in 28 forest plots (10 m × 10 m) spanning an 800 m elevation gradient. For each trait in each plot, we computed community‐weighted means (CWMs) and the standardized effect size of functional diversity (SES‐FD). We decomposed total trait variation into its interspecific and intraspecific components, and their covariation. We run linear regression models to assess the impact of elevation on these three components of functional variation. Lastly, we investigated whether higher elevation communities exhibited lower SES‐FD, indicating functional convergence that could hint to a stronger habitat filtering.ResultsInterspecific trait variation was more important than the intraspecific counterpart both for CWMs and SES‐FD. Only CWMs calculated for plant height and LDMC showed a significant relationship with elevation. Low‐elevation communities featured taller, more‐conservative species, whereas shorter, faster‐growing species were more common at higher elevations. SES‐FD remained consistently negative for species turnover and total variation, suggesting stable functional convergence across the gradient.ConclusionsOur findings suggest that interspecific and intraspecific trait variability can be decoupled along an elevation gradient, stressing the importance of individually considering each component of trait variation when studying community composition. Elevation significantly influenced various components of plant community trait variation, with habitat filtering playing a substantial role in selecting plants with specific traits across elevations.

Reorganization of bird communities along a rainforest elevation gradient during a strong El Niño event in Papua New Guinea.

The El Niño 2015 event, most extreme since 1997, led to severe droughts in tropical wet Papua New Guinea (PNG), reducing May to October dry season rainfall by 75% in the lowlands and 25% in the highlands. Such droughts are likely to have significant effects on terrestrial ecosystems, but they have been poorly explored in Papua New Guinea. Here, we report changes in bird community composition prior to, during, and after the 2015 El Niño event along the elevational gradient ranging from 200 m to 2700 m a.s.l. at the Mt. Wilhelm rainforest in PNG. The abundance of birds in the lowlands dropped by 60% but increased by 40% at elevations above 1700 m during El Niño year. In the following year, the individual bird species reached mean population sizes similar to pre-El Niño years but did not fully recover. Species richness roughly followed the pattern of observed abundance and quickly and fully re-established after the event to the pre- El Niño values. Thus, at least some terrestrial birds seem to react quickly to the extreme droughts in lowlands and shift to less affected mountain habitats. We recorded upper elevational range limits to shifts by more than 500 m a.s.l. in 22 bird species (out of 237 recorded in total) during El Niño year, in contrast to their typical ranges. Our study suggests that a strong El Niño event can have strong but reversible effects on bird communities as long as they have an opportunity to move to more favorable sites through undisturbed habitats.

Biophysical Modeling of Mangrove Seedling Establishment and Survival Across an Elevation Gradient With Forest Zones

AbstractMangrove forest development critically depends on the establishment and survival of seedlings. Mechanistic insights into how water levels, waves and bed level dynamics influence the establishment process of individual mangrove seedlings are increasing. However, little is known about how spatial and temporal changes in water levels, waves and bed level dynamics across elevation gradients in mangrove forests facilitate/limit seedling dynamics. For this study, a new seedling establishment and growth model was integrated into a process‐based hydrodynamic and morphodynamic numerical model. This biophysical model was applied to a fringing mangrove forest located in the southern Firth of Thames, Aotearoa, New Zealand. This study quantifies the increasing establishment density and survival probability of mangrove seedlings from the lower‐elevated unvegetated intertidal flat toward the higher‐elevated mature mangrove forest. Three cross‐shore zones with distinctive seedling dynamics were identified: (a) a zone with daily tidal inundation where seedling dynamics are episodic and limited by the dispersal of individual propagules that rapidly anchor to the substrate by root growth, (b) a zone with daily to bi‐weekly tidal inundation where seedling dynamics respond to variations in spring‐neap tidal cycles and, (c) a zone with less than bi‐weekly inundation where seedling dynamics are governed by high propagule supply and seedling survival probability. The seedling establishment density and survival probability are dominated by annual extremes in tidal hydroperiod and bed shear stresses, respectively. The obtained parameterizations can be used to incorporate seedling dynamics in decadal‐timescale mangrove forest development models that are instrumental for mangrove management and restoration.

Diversity and distribution of chironomids in Central European ponds.

Ponds are common freshwater habitats in the European landscape that substantially contribute to local and regional biodiversity. Chironomids often dominate invertebrate communities in ponds but are usually disregarded in ecological studies due to relatively complicated taxonomy and identification issues. We present a comprehensive overview of the chironomid diversity in 246 ponds spanning a wide range of conditions extending from the Pannonian Plain to the Carpathians. Altogether, we recorded 225 taxa including 192 species from six subfamilies (Podonominae, Tanypodinae, Diamesinae, Prodiamesinae, Orthocladiinae and Chironominae). However, the chironomid taxa inventory is far from complete and about 16% of the total diversity of pond-dwelling chironomids remains undetected. Chironomid alpha diversity showed a significant unimodal pattern along the elevation gradient with the highest number of taxa per pond expected around 790 m a.s.l. Gamma diversity also peaked in mid-elevations (600-800 m), and the common chironomid taxa partitioned the 2100-m long altitudinal gradient relatively evenly. The heterogeneity of chironomid communities among ponds measured as beta diversity was significantly higher in elevations below 800 m. Temperature and the proportion of surrounding forests significantly influenced alpha diversity of chironomid communities, while urban land cover and pond size had no significant effect. Ponds with a mean annual air temperature of approximately 4.8°C and a low proportion of surrounding forests are expected to harbour the most diverse chironomid communities. Our study showed that chironomids represent a very diverse and often exceptionally rich group of pond-dwelling macroinvertebrates. Given the high diversity and broad range of occupied niches, chironomids should not be overlooked in pond ecology studies. On the contrary, they should be considered a potential model group.

Most High Mountainous Areas Around the World Present Elevation‐Dependent Aridification After the 1970s

AbstractThe research on the trends of mountainous aridity and the issue of elevation‐dependent aridity (EDA) has long been hindered by limitations in data validity. In this study, we present global monthly merged data sets of Vapor Pressure Deficit and Aridity Index (AI) from 1960 to 2020, aiming to detect and attribute elevation‐dependent patterns of atmospheric and soil aridity in six representative high mountainous areas worldwide. Our findings reveal that most of the mountainous regions experienced significant aridification after the 1970s (p < 0.05). The Rocky Mountains and Ethiopian Highlands are identified as the most vulnerable areas, with both atmospheric and soil aridity increasing by 13% across all elevation gradients. Significant humidification has been observed only in High Asian Regions at 4,000 m above sea level with an approximate decrease of 11% in soil AI. In both temporal and spatial patterns, soil aridity exhibits stronger heterogeneity compared to atmospheric aridity, with certain regions and seasons showing humidification, despite the overall aridification trend. Elevation‐dependent aridity is observed in two‐thirds of the mountains, but whether high altitude alleviates or amplifies aridity depends on the pattern of precipitation changes at different elevations. The rise in air temperature is the primary driving factor for soil and atmospheric aridification, contributing to over 50% of each. In two‐thirds of the regions, changes in precipitation exacerbate soil aridity. Simulations show that human activities are closely related to the ongoing prolonged atmospheric aridification. This study contributes to a comprehensive understanding of global mountainous aridity evolution projected under climate change.

CLINICAL ASSOCIATIONS AND ON-TREATMENT CHANGES OF CENTRAL SYSTOLIC BLOOD PRESSURE AND AR TERIAL STIFFNESS IN PATIENTS WITH DECOMPENSATED HEART FAILURE

Objective: Heart failure (HF) remains one of the major causes of cardiovascular mortality worldwide. The results of studies on arterial stiffness (AS) and central blood pressure (cBP) in HF are contradictory. The aim of this study was to evaluate clinical associations of cBP and parameters of AS and their on-treatment changes after 6 months of stable guideline-directed medical therapy (GDMT) in patients with acute decompensated HF (ADHF). Design and method: In 54 patients (61% males, 69.6±10 years, HTN 100%, median (med) EF 51% (IQR 38;55%), NTproBNP 623 (500;1842)pg/ml; HFrEF 37%, HFmrEF 13%, HFpEF 50%), apart from routine tests (including congestion assessment by bioimpedance vector analysis, lung ultrasound, liver density by FibroScan, and venous excess ultrasound) we assessed cBP and AS with applanation tonometry (SphygmoCor) within 3-4 days after admission and after 6 months. cSBP>/=individual reference values, carotid-femoral pulse wave velocity (cfPWV)>10 m/s and >individual reference values, AS gradient (cfPWV/carotid-radial PWV) >/=1 were considered abnormal. p<0.05 was considered significant. Results: At admission and after 6 months med brachial (b)BP was 117(106;130)/70 (68;80) mmHg 116 (108;130) mmHg, bPP 47 (37;56) mmHg and 47 (39;55) mmHg (p>0.05); cBP 109.5(96;120.5)/71.5 (68;80) mmHg and 106.5(95;113)/73 (65;79) mmHg (p=0.02 for cSBP), cPP 35 (25;43) mmHg and 32.5 (24;38) mmHg (p>0.05), cfPWV 9.9 (6.8;13) m/s and 11.4 (8.5,14.4), m/s (p=0.04), augmentation index (AI@HR75) 20% (13;33%) and 24.5% (18;29%), (p=0.05), PP amplification 129 (120;146) mmHg and 126 (121;136) mmHg, (p=0.02), AS gradient 1.2 (0.9;1.8) and 1 (0.8;1.4) (p>0.05), respectively. Elevated cSBP at admission was observed in 33%, at 6 months – in 38.1%, PWV>10 m/s-in 48.1% and 61.9% respectively, cfPWV>individual reference values–in 33.3% and 66.7% respectively, AS gradient>/=1–in 70.3% and 95.2% respectively. There were no differences in parameters of AS and cSBP and frequencies of their elevation across EF phenotypes and no differences between groups with normal and elevated AS by characteristics of congestion. Conclusions: Patients admitted with ADHF had high frequency of CBP elevation and abnormal AS gradient. The significant increase in cSBP, cfPWV and decrease in PP amplification on stable GDMT needs further evaluation.

Cushions serve as conservation refuges for the Himalayan alpine plant diversity: Implications for nature-based environmental management

Globally, rapid climate and land-use changes in alpine environments are posing severe risks to their bountiful biodiversity and ecosystem services. Currently, nature-based solutions are fast-emerging as the preferred approach to address the challenges of environmental sustainability. In alpine environments, cushion plants owing to their unique architecture and adaptability offer a potential nature-based system to plan biodiversity conservation and habitat restoration strategies. Here, we employed an analytical framework to test whether and how the cushion plants facilitate the sustenance of alpine plant diversity in Kashmir Himalaya. We specifically aimed to answer: what are the effects of the cushion plants on the patterns of alpine species richness and phylogenetic diversity, and whether these effects vary across spatial scales (local versus landscape), cushion types, and changing elevation. We randomly selected pairs of cushion and neighbouring non-cushion plots (size 100 m2) across 34 different alpine sites in the study region. Within each plot, we randomly laid three 5 m2 quadrats for vegetation sampling, and sampled a total of 204 quadrats in 68 plots with seven cushion types along elevation ranging from 3100 to 3850 m. Our results revealed positive effects of the cushions by supporting a higher community species richness (SR) and phylogenetic diversity (PD). The effects were consistent both at the local (i.e., quadrat) and landscape (i.e., plot) scales, but varied significantly with the cushion type. Interestingly, SR and PD showed an increasing trend with increase in elevation in cushion communities, thereby supporting stress gradient hypothesis. Along the elevational gradient, the cushion communities showed phylogenetic overdispersion, but clustering by non-cushions. Overall, our study provides empirical evidence to reinforce the role of the cushions as conservation refugia for an imperilled alpine plant diversity in the Himalaya. Looking ahead, we highlight the far-reaching implications of our findings in guiding the nature-based environmental management of alpine ecosystems worldwide.

Dynamics of Soil Physical and Chemical Properties under Different Current Land Use Types and Elevation Gradients in the Sala Watershed of Ari Zone, South Ethiopia

The dynamics of soil physical and chemical properties have been increasing due to inappropriate land use and unsustainable land management practices in Ethiopia. This study aims to assess the dynamics of selected soil physical and chemical properties under different current land use types and altitudinal gradients in the Sala watershed of Ari Zone in South Ethiopia. In the study area, analyzing and understanding the dynamics of soil physicochemical properties under different land use types play a vital role in sustainable soil productivity. Before collecting a soil sample, land use types and altitudinal variations were surveyed in the study watershed. Three random strata were selected from the watershed, and the major adjacent land use types in each stratum were identified across elevation gradients. A total of 30 composite soil samples were collected from different land uses and elevations using a zigzag sampling technique at 0–20 cm soil depth from upland (12), midland (9), and lowland (9). Laboratory results showed that most soil physical and chemical properties had poor ratings in the watershed area. All soil properties were significantly affected by land use types and elevation factors (P<0.05), except for soil texture, TN, and CEC. Soil texture is highest in the upper and lower elevations of grazing land (61.3%) and shrubland (55.4%), while lowest in cultivated land (11.3%) and barren land (11.6%) at higher altitudes. The highest mean of soil texture was dominated by clay soil (55%) in shrubland followed by sand soil (50.30%) in the barren land and silt soil (20.06%) in cultivated land. Chemical soil properties (pH, SOM, TN, Av. P, Av. K, and CEC) were significantly varied under each land use type across altitudes. The results of this study showed that inappropriate land use and unsustainable agricultural practices had more significantly influenced the soil fertility status. Therefore, appropriate soil and water conservation measures should be implemented in the studied watershed to improve soil fertility and crop productivity.

Searching for nature-based solutions: Molecular ecology of an endangered Himalayan medicinal herb shows roadmap for conservation and sustainable utilization

In recent times, to meet the surging demand of the herbal industry, overharvesting of medicinal herbs from their natural habitats has accelerated. This has posed severe extinction risks to plant species worldwide and therefore requires urgent conservation efforts and long-term sustainable solutions. By employing a molecular ecology approach, here we showcase a sustainable solution model for an endemic Himalayan medicinal herb, Trillium govanianum. The herb, being a rich source of diosgenin, is currently overharvested for its rhizome by extraction of the whole plant from the wild, leading to a drastic decline in its natural populations, and now declared Endangered. In the present study, we investigated whether there is an alternative sustainable source of diosgenin (i.e. leaves) other than rhizome in T. govanianum. We studied the spatial dynamics of diosgenin biosynthesis and accumulation using qRT-PCR-based targeted gene expression and High-Performance Liquid Chromatography-based diosgenin quantification in the leaf and rhizome samples of T. govanianum collected along the elevation gradients in Kashmir Himalaya. Our results revealed a higher diosgenin content in the leaf than in rhizome samples of T. govanianum. Expression analysis showed that, compared to the rhizome, the leaf samples exhibit relatively higher expression of all the seven genes of the diosgenin biosynthesis pathway. We also found a strong positive correlation between the expression of the targeted genes and diosgenin content in the leaf and rhizome samples. Overall, our findings offer a nature-based solution for the conservation and sustainable utilization of this imperiled endemic Himalayan herb, with lessons for elsewhere in the world.

Development of a temperate rainforest zonation on the Pacific slopes of the North Patagonian Andes since ∼18 ka

Few studies along the western slopes of the Andes in Northwestern Patagonia (NWP: 40°-44°S) allow examining vegetation development through environmental gradients in latitude and elevation along a time continuum since the Last Glacial Termination (T1, ∼18-11 ka). This complete biostratigraphic context is necessary for assessing the sequence, timing, rates, and direction of compositional/structural changes of the former vegetation, and for deciphering their environmental drivers. Here we report palynological results from two NWP sites spaced ∼22 km apart on the western Andean slopes, Caleta Puelche roadside section located near sea level and Lago Reflejos at mid elevations (∼800 m a.s.l.) and assess their continuous records since local ice-free conditions against other NWP sites. We find that cold-tolerant early successional trees dominated the initial stages of vegetation development in the Seno Reloncaví lowlands (∼18-17 ka), followed by thermophilous shade-tolerant North Patagonian rainforest (NPRF) trees, which achieved their maxima between ∼17 and 15 ka at low-elevations. A spread of cold- and shade-tolerant hygrophilous NPRF conifers ensued (∼14.8-13 ka) reaching similar magnitude at low- and mid-elevations, interrupted by increases in trees favored by canopy fragmentation linked to fire and explosive volcanism (∼13-11 ka). Thermophilous, shade-intolerant, summer-drought tolerant Valdivian rainforest (VRF) trees increased and achieved maxima between ∼10 and 8 ka, most notably in the lowlands, coeval with peak abundance of the NPRF conifers Fitzroya/Pilgerodendron and Podocarpus nubigena in mid-elevation Lago Reflejos, contemporaneous with their virtual disappearance near sea level. Widespread increases in cold-tolerant hygrophilous NPRF trees occurred after ∼8 ka, followed by mixing of NPRF and VRF elements in the lowlands after ∼6.3 ka with centennial-scale alternations. Inter-site and regional coherences of our findings suggest that variations in Southern Westerly Wind influence, along with disturbance regimes of natural and human origin, have driven the composition, structure, dynamics, and zonation of temperate rainforests in NWP since T1. We observe that Lago Reflejos features the highest abundance of Fitzroya cupressoides at regional scale since ∼12 ka, attesting to the importance of mid-elevation Andean environments for the persistence of these highly valued trees in the context of postglacial climate evolution, shifts in fire regimes, volcanic, and human disturbance in NWP.

Interannual precipitation variability dominates the growth of alpine grassland above-ground biomass at high elevations on the Tibetan Plateau

The impact of global climate change on mountainous regions with significant elevational gaps is complex and often unpredictable. In particular, alpine grassland ecosystems, are experiencing changes in their spatial patterns along elevational gradients, which increases their vulnerability to degradation. Therefore, a more detailed understanding of spatiotemporal changes in alpine grassland productivity along elevational gradients and an elevation-dependent characterization of the effects of climatic variables on grassland productivity dynamics are essential. Thus, we conducted a study in the Tibetan Plateau, where we collected 2251 above-ground biomass (AGB) observations collected from 1986 to 2020. Mean annual temperature (TMP), annual precipitation (PRE), interannual precipitation variability (CVP), and snowmelt (SNMM) were chosen as influential variables. Using the Random Forest algorithm, we generated an AGB raster dataset covering the period 1989–2020 based on earth observation data at 30 m resolution to examine the dynamics of alpine grasslands and their response to climate change with respect to elevation. The results showed that the AGB of alpine grassland on the Tibetan Plateau was 49.17 g/m2. We observed an increasing trend in grassland AGB at high elevations, with a growth rate of about 0.28 g/m2 per year within the interval of 3100–4800 m. However, above the elevation of approximately 4400–4600 m, we observed a decoupling trend between grassland AGB and TMP. Moreover, at most elevations, the proportion of maximum partial correlation coefficients for CVP, PRE, and SNMM surpassed that of TMP. We found the dominant role of precipitation variability on grassland AGB dynamics, with 22.80 % and 18.86 % for CVP+ and CVP-, respectively. The proportion of CVP+ did not vary much at different elevations, whereas the proportion of CVP- increased with elevation, varying between 12.85 and 30.25 %. In the future, precipitation on the Tibetan plateau is expected to increase, potentially reversing its original positive impact.

Pain control and neonatal outcomes in 211 women under epidural anesthesia during childbirth at high altitude in Qinghai, China.

High altitudes are characterized by low-pressure oxygen deprivation. This is further exacerbated with increasing altitude. High altitudes can be associated with reduced oxygenation, which in turn, can affect labor, as well as maternal and fetal outcomes. Epidural anesthesia can significantly relieve labor pain. This study aimed to assess the effects of elevation gradient changes at high altitude on the analgesic effect of epidural anesthesia, labor duration, and neonatal outcomes. We divided 211 women who received epidural anesthesia into groups according to varying elevation of their residence (76 in Xining City, mean altitude 2,200 m; 63 in Haibei Prefecture, mean altitude 3,655 m; and 72 in Yushu Prefecture, mean altitude 4,493 m). The analgesic effect was assessed using a visual analog scale (VAS). Labor duration was objectively recorded. The neonatal outcome was assessed using Apgar scores and fetal umbilical artery blood pH. VAS scores among the three groups did not differ significantly (p > 0.05). The neonatal Apgar scores in descending order were: Xining group > Haibei group > Yushu group (p < 0.05). The stage of labor was similar among the three groups (p > 0.05). Fetal umbilical artery blood pH in descending order were: Xining group > Haibei group > Yushu group (p < 0.05). Elevation gradient changes in highland areas did not affect the efficacy of epidural anesthesia or labor duration. However, neonatal outcomes were affected.

Transect walks and malaise traps differ in temperature sensitivity but reveal consistent drivers of pollinator richness

Abstract While transect walks have long been the preferred monitoring method for many flying insect taxa, malaise traps combined with DNA metabarcoding have gained growing prominence. However, it remains unclear whether both methods reveal comparable species richness and the same ecological drivers along environmental gradients. We selected three groups of pollinators (wild bees, hoverflies and butterflies) and one group of herbivores (grasshoppers) as functionally important and conservation‐relevant model groups, comparing results of both methods along an elevational gradient in the German Alps. Across the study region, both methods detected a similarly high species richness of pollinators with ~50% overlap of species pools, but transect walks revealed more species per site, especially in higher elevations and under low temperatures. Body size spectra differed between methods, with on average more large butterfly and more small bee species in transect walks. Nevertheless, temperature and flower richness were consistent drivers of pollinator richness, independent of the sampling method. Grasshopper richness from transect walks was considerably higher than from malaise traps. Both methods identified temperature and only malaise traps also identified management as drivers of grasshopper richness. We conclude that malaise traps are principally suitable substitutes for the more time‐consuming pollinator transect walks. However, the effectiveness of these passive traps is more susceptible to changes in sampling temperature, and in some pollinator groups, body size classes are presented differently, which is important to consider during analyses. For grasshoppers, transect walks appear to be more suitable to assess species richness, as considerably more species can be monitored.

Elevated [CO2] and temperature augment gas exchange and shift the fitness landscape in a montane forb.

Climate change is simultaneously increasing carbon dioxide concentrations ([CO2]) and temperature. These factors could interact to influence plant physiology and performance. Alternatively, increased [CO2] may offset costs associated with elevated temperatures. Furthermore, the interaction between elevated temperature and [CO2] may differentially affect populations from along an elevational gradient and disrupt local adaptation. We conducted a multifactorial growth chamber experiment to examine the interactive effects of temperature and [CO2] on fitness and ecophysiology of diverse accessions of Boechera stricta (Brassicaceae) sourced from a broad elevational gradient in Colorado. We tested whether increased [CO2] would enhance photosynthesis across accessions, andwhether warmer conditions would depress the fitness of high-elevation accessions owing to steep reductions in temperature with increasing elevation in this system. Elevational clines in [CO2] are not as evident, making it challenging to predict how locally adapted ecotypes will respond to elevated [CO2]. This experiment revealed that elevated [CO2] increased photosynthesis and intrinsic water use efficiency across all accessions. However, these instantaneous responses to treatments did not translate to changes in fitness. Instead, increased temperatures reduced the probability of reproduction for all accessions. Elevated [CO2] and increased temperatures interacted to shift the adaptive landscape, favoring lower elevation accessions for the probability of survival and fecundity. Our results suggest that elevated temperatures and [CO2] associated with climate change could have severe negative consequences, especially for high-elevation populations.

Topographical gradient of the structure and diversity of a woody plant community in a seasonally dry tropical forest in northwestern Madagascar

AbstractFew studies have evaluated the structure and dynamics of forests in Madagascar with high levels of endemism. Ankarafantsika National Park holds the largest of the remaining primary dry forests in northwestern Madagascar, where most of the forests have been lost or degraded by fire and other human activities. In this primary forest, we established a 15‐ha forest dynamics monitoring plot and mapped and identified all woody stems with a diameter at breast height (DBH) ≥5 cm. The forest stand was characterized by small‐sized individuals (75% of stems with DBH &lt;10 cm, with 99% of trees with height &lt;15 m), encompassing 35,758 tree and 513 liana individuals belonging to 160 species in 53 families (including 20 species of lianas accounting for 1.4% of the stems). Most species‐rich families were Rubiaceae, Fabaceae, Lamiaceae, and Malvaceae, which together encompassed 43 tree species and 23% of all tree individuals. The plot was located on a hill consisting of white sand at elevations from 150 to 200 m, with a gentle slope down from southwest to northeast. Over this elevation gradient, stem density and species diversity increased with elevation, while tree height and diameter decreased. The most abundant two species, Drypetes perrieri (Putranjivaceae) and Noronhia alleizettei (Oleaceae) are evergreen, suggesting the importance of a nutrient conservation strategy. These results provide the foundational knowledge necessary for the conservation and restoration of natural semi‐deciduous dry forests that used to cover large areas in northwestern Madagascar until recently.

Leaf traits and leaf‐to‐air temperature differences in tropical plants suggest variability in thermoregulatory capacities across elevations

AbstractPlant thermoregulation is essential for understanding the potential effects of climate change on terrestrial ecosystems. This study provides evidence indicating variation of leaf functional traits and leaf‐to‐air temperature across the elevation gradient. These results support the existence of distinct plant adaptations for thermoregulation across different elevation zones.Abstract in Spanish is available with online material.

Correction to Bromeliad populations perform distinct ecological strategies across a tropical elevation gradient

Correction to Bromeliad populations perform distinct ecological strategies across a tropical elevation gradient

Pleistocene glaciation advances the cryptic speciation of Stellera chamaejasme L. in a major biodiversity hotspot.

The mountains of Southwest China comprise a significant large mountain range and biodiversity hotspot imperiled by global climate change. The high species diversity in this mountain system has long been attributed to a complex set of factors, and recent large-scale macroevolutionary investigations have placed a broad timeline on plant diversification that stretches from 10 million years ago (Mya) to the present. Despite our increasing understanding of the temporal mode of speciation, finer-scale population-level investigations are lacking to better refine these temporal trends and illuminate the abiotic and biotic influences of cryptic speciation. This is largely due to the dearth of organismal sampling among closely related species and populations, spanning the incredible size and topological heterogeneity of this region. Our study dives into these evolutionary dynamics of speciation using genomic and eco-morphological data of Stellera chamaejasme L. We identified four previously unrecognized cryptic species having indistinct morphological traits and large metapopulation of evolving lineages, suggesting a more recent diversification (~2.67-0.90 Mya), largely influenced by Pleistocene glaciation and biotic factors. These factors likely influenced allopatric speciation and advocated cyclical warming-cooling episodes along elevational gradients during the Pleistocene. The study refines the evolutionary timeline to be much younger than previously implicated and raises the concern that projected future warming may influence the alpine species diversity, necessitating increased conservation efforts.

Contraction and expansion: global geographical variation in reproductive systems of Primula is driven by different mechanisms

AbstractAimReproductive systems strongly influence plants' evolution and adaption, and the biogeographic pattern of its variation has intrigued biologists and ecologists. Here, to test the impacts of paleoglaciation on plants' reproductive system variation, we compared the geographical pattern and environmental drivers in the proportions of different reproductive systems in Primula in regions affected and unaffected by paleoglaciation.LocationGlobal.Time PeriodSince the Last Glacial Maximum (LGM).Major Taxa Studied Primula. MethodsUsing data on reproductive systems and distributions of 604 Primula taxa around the world and 221 along the elevational gradient of the Himalayas, we demonstrated the global pattern and the elevational pattern in the proportions of homostylous taxa. We employed general linear models to establish the relationship between the proportion of homostylous taxa and environmental variables and hierarchical partitioning to assess the relative contributions of these variables in both regions affected and unaffected by paleoglaciation, respectively.ResultsWe found a higher proportion of homostylous taxa in regions glaciated during the LGM than those unglaciated, with different latitudinal patterns and climate drivers. The proportion of homostylous taxa showed varying trends across different regions: increasing with latitude and temperature anomaly in glaciated regions while concentrating at lower latitudes with higher winter temperatures in unglaciated regions. Additionally, homostylous taxa were more prevalent at lower elevations in the Himalayas.Main ConclusionsOur study provides the first quantitative evidence for the hypothesis that selfers are more prevailing in regions affected by paleoglaciation facilitated by recolonization via comparing the geographic pattern and drivers in regions affected and unaffected by paleoglaciation. Our findings also reveal the concentrated distribution of homostylous taxa in Primula at low latitudes, which may be the result of population shrinkage caused by heat stress, facing a more severe survival crisis under the circumstances of global warming and increasing human activities.