Climate-growth relationships of Pinus tabuliformis along an altitudinal gradient on Baiyunshan Mountain,Central China

A set of standard chronologies for tree-ring width(TRW),earlywood width(EWW)and latewood width(LWW)in Pinus tabuliformis Carr.along an altitudi-nal gradient(1450,1400,and 1350 m a.s.l.)on Baiyunshan Mountain,Central China to analyze the effect of varying temperature and precipitation on growth along the gradi-ent.Correlation analyses showed that at all three altitudes and the TRW and EWW chronologies generally had signifi-cant negative correlations with mean and maximum tem-peratures in the current April and May and with minimum temperatures in the prior July and August,but significant positive correlations with precipitation in the current May.Correlations were generally significantly negative between LWW chronologies and all temperatures in the prior July and August,indicating that the prior summer temperature had a strong lag effect on the growth of P.tabuliformis that increased with altitude.The correlation with the standard-ized precipitation evapotranspiration index(SPEI)confirmed that wet conditions in the current May promoted growth of TR and EW at all altitudes.Significant altitudinal differences were also found;at 1400 m,there were significant positive correlations between EWW chronologies and SPEI in the current April and significant negative correlations between LWW chronologies and SPEI in the current September,but these correlations were not significant at 1450 m.At 1350 m,there were also significant negative correlations between the TRW and the EWW chronologies and SPEI in the prior October and the current July and between LWW chronology and SPEI in the current August,but these cor-relations were not significant at 1400 m.Moving correlation results showed a stable response of EWW in relation to the SPEI in the current May at all three altitudes and of LWW to maximum temperature in the prior July-August at 1400 m from 2002 to 2018.The EWW chronology at 1400 m and the LWW chronology at 1450 m were identified as more suitable for climate reconstruction.These results provide a strong scientific basis for forest management decisions and climate reconstructions in Central China.

Climate Variability and Soil Nutrients Status along Altitudinal Gradient in Kigezi Highlands, Southwestern Uganda

Kigezi highlands currently experiences changes in precipitation and temperature which modify the evaporation and soil moisture storage leading to alterations in runoff and other components of hydrological systems. Extreme events, like floods and droughts, are more intense and frequent. Furthermore heavy unpredictable rainfall has become frequent in the area, causing soil erosion and floods that destroy crops. Soil erosion is particularly a pressing challenge due to steep-sided hills leading to deterioration of soil nutrients including soil fertility. The unpredictable rains and droughts are attributed to climate change and variability. Consequently, climate change and variability have caused a significant impact on soil nutrients which have affected the agricultural productivity in the area. This paper presents findings of empirical study which explored the climate variability and soil nutrient status along altitudinal gradient. The paper particularly addresses key questions of: land management practices in the study area, nutrient availability and their effects on productivity of selected crops along altitudinal gradient in changing climate and variability. Independent variables such as topographic sequence along altitudinal gradient were evaluated against dependent variables such as yield harvests of selected grown crops and soil nutrients. Samples for crop yields were collected along transect of 0.5 kilometer using a quadrant of 4 × 4 m2 along attitudinal gradient. Soil samples were taken from selected plots at 0-20cm soil depth for nutrient analysis. Analysis of physical and chemical soil parameters was carried out on soil samples and these include: soil pH, soil organic content, total nitrogen, available soil phosphorous and exchangeable bases (Ca, Mg, K and Na). The study showed that middle parts of the transects had the highest concentration of most soil nutrients, probably because the middle parts could have been a deposition centre for some organic matter from the upper parts of the hills, and lower lying areas were being affected by floods that affects the decomposition of organic matter which is the main source of nutrients. Similarly, the middle parts of the study were the most fertile due to the high concentration of soil nutrient compositions. This indicates that crop yields were significantly affected by availability of soil nutrients along same gradient, attributable to the severity in soil erosion, nutrients leaching and farming practices.

Variation and Sexual Dimorphism of Body Size in the Plateau Brown Frog along an Altitudinal Gradient

Variation in body size and sexual size dimorphism（SSD） can have important consequences for animal ecology, behavior, population dynamics and the evolution of life-history traits. Organisms are expected to be larger in colder climate（i.e., Bergmann＇s rule） and SSD varies with body size（i.e., Rensch＇s rule）. However, the underlying mechanisms are still elusive. The plateau brown frog（Rana kukunoris）, a medium-sized anuran species with femalebiased SSD, is endemic to the Qinghai-Tibetan Plateau（QTP）. From 1797 m（Maoxiang＇ping） to 3453 m（Heihe＇qiao） in the eastern margin of the QTP, we surveyed 10 populations of R. kukunoris and collected phalanges and snout vent length（SVL） data for 258 adult individuals（199 males versus 59 females）. Based on these data, we explored how body size and SSD varying along the altitudinal gradient and examined the corresponding effects of temperature. We found body size to be larger at higher altitude for males but not for females, with likely effects from the temperature on the variation in male body size. Sex differences in growth rates may be the main cause of the variation in SSD. Our results suggested that only males follow the Bergmann＇s rule and variation in SSD of R. kukunoris do not support the Rensch＇s rule and its inverse. Therefore, the variations of body size can be different between sexes and the applicability of both Bergmann＇s rule and Rensch＇s rule should depend on species and environment where they live.

Seedling potential of trees species along the elevational gradient in temperate hill forest of central Nepal

Regeneration status of tree species along elevation gradient in temperate hill forest was not understood greatly.Present research examined the tree diversity and its regeneration patterns along an elevation gradient in temperate hill forest,central Nepal.Data were collected from 300 sample plots within vertical elevation bands of 10,ranging from 1365 to 2450 m asl.A random sampling method was used for data collection in three seasons,winter,pre-monsoon and post monsoon seasons.Diameter at breast height(DBH)was used to broadly categorize the plant individual into trees,saplings and seedlings.The tree species richness ranged from 12 to 25 with density of 350 to 1200 individuals per hectare.Species richness of tree and sapling showed statistically significant unimodal pattern,which peaked at mid-elevation.Elevation showed a strong and positive linear correlation with the seedling density(Deviance=0.99,p<0.001)and a significant hump-shaped relationship with sapling density(Deviance=0.95,p<0.001).Similarly,elevations showed a statistically significant negative hump-shaped relationship with all trees,saplings and seedling stages(Deviances=0.89,0.87 and 0.57).The highest values of the Shannon-Wiener index and the lowest value of the Simpson index were found at mid-elevation for all growth forms.Nearly 92%of tree species were found at regenerating stage;49%in a good renewal regeneration status,32%in fair renewal regeneration,and 11%at a poor regenerating condition.Nevertheless,4%of tree species were reported as non-regenerating stages and 4%were newly introduced species.Hence,the regeneration status of the study area was considered fairly well since sapling(78.5%)>seedling(10.6%)≤mature(10.9%).Among tested environmental variables,elevation and annual mean rainfall were the most influential factors in the regeneration of tree species.

Woody plant taxonomic,functional,and phylogenetic diversity decrease along elevational gradients in Andean tropical montane forests:Environmental filtering and arrival of temperate taxa

Mountains are paramount for exploring biodiversity patterns due to the mosaic of topographies and climates encompassed over short distances.Biodiversity research has traditionally focused on taxonomic diversity when investigating changes along elevational gradients,but other facets should be considered.For first time,we simultaneously assessed elevational trends in taxonomic,functional,and phylogenetic diversity of woody plants in Andean tropical montane forests and explored their underlying ecological and evolutionary causes.This investigation covered four transects(traversing ca.2200 m a.s.l.) encompassing 114 plots of 0.1 ha across a broad latitudinal range(ca.10°).Using Hill numbers to quantify abundance-based diversity among 37,869 individuals we observed a consistent decrease in taxonomic,functional,and phylogenetic diversity as elevation increased,although the decrease was less pronounced for higher Hill orders.The exception was a slight increase in phylogenetic diversity when dominant species were over-weighted.The decrease in taxonomic and functional diversity might be attributed to an environmental filtering process towards highlands,where the increasingly harsher conditions exclude species and functional strategies.Besides,the differences in steepness decrease between Hill orders suggest that rare species disproportionately contribute to functional diversity.For phylogenetic diversity the shifting elevational trend between Hill orders indicates a greater than previously considered influence in central Andean highlands of tropical lowlands originated species with strong niche conservatism relative to distantly related temperate lineages.This could be explained by a decreasing presence and abundance of temperate,extratropical taxa towards the central Andes relative to northern or southern Andes,where they are more prevalent.

Vegetation distribution pattern along altitudinal gradient in subtropical mountainous and hilly river basin, China

Knowledge of vegetation distribution patterns is very important. Their relationships with topography and climate were explored through a geographically weighted regression （GWR） framework in a subtropical mountainous and hilly region, Minjiang River Basin of Fujian in China. The HJ-1 satellite image acquired on December 9, 2010 was utilized and NDVI index was calculated representing the range of vegetation greenness. Proper analysis units were achieved through segregation based on small sub-basins and altitudinal bands. Results indicated that the GWR model was more powerful than ordinary linear least square （OLS） regression in interpreting vegetation-environmental relationship, indicated by higher adjusted R2 and lower Akaike information criterion values. On one side, the OLS analysis revealed dominant positive influence from parameters of elevation and slope on vegetation distribution. On the other side, GWR analysis indicated that spatially, the parameters of topography had a very complex relationship with the vegetation distribution, as results of the various combinations of environmental factors, vegetation composition and also anthropogenic impact. The influences of elevation and slope generally decreased, from strongly positive to nearly zero, with increasing altitude and slope. Specially, most rapid changes of coefficients between NDVI and elevation or slope were observed in relatively flat and low-lying areas. This paper confirmed that the non-stationary analysis through the framework of GWR could lead to a better understanding of vegetation distribution in subtropical mountainous and hilly region. It was hoped that the proposed scale selection method combined with GWR framework would provide some guidelines on dealing with both spatial （horizontal） and altitudinal （vertical） non-stationarity in the dataset, and it could easily be applied in characterizing vegetation distribution patterns in other mountainous and hilly river basins and related research.

A test of BIOME-BGC with dendrochronology for forests along the altitudinal gradient of Mt. Changbai in northeast China

Aims Process-based models are basic tools for predicting the response of forest carbon to future climate change.The models have commonly been tested for their predictions of spatial variation in forest produc-tivity,but much less for their ability to predict temporal variation.Here,we explored methods to test the models with tree rings,using BIOME-BGC as an example.Methods We used net primary productivity(NPP)data and tree rings col-lected from five major forest types along the altitudinal gradient of Mt.Changbai,northeast China,to test local-parameterized BIOME-BGC model.We first test the model’s predictions of both spatial(Test 1)and temporal changes(Test 2)in productivity.Then we test if the model can detect the climatic factors limiting forest productiv-ity during historical climate change,as revealed by dendroclimatic analyses(Test 3).Important Findings Our results showed that BIOME-BGC could well simulate NPP of five forest types on Mt.Changbai,with an r^(2) of 0.69 between mod-eled and observed NPP for 17 plots along the altitudinal gradient(Test 1).Meanwhile,modeled NPP and ring-width indices were cor-related and showed similar temporal trends for each forest type(Test 2).While these tests suggest that the model’s predictions on spatial and temporal variation of NPP were acceptable,a further test that relate the correlations of modeled NPP with climate variables to the correlations of ring widths with climate(Test 3)showed that the model did not well identify the climatic factors limiting historical productivity dynamics for some forest types,and thus cannot reli-ably predict their future.Both dendrochronology and BIOME-BGC showed that forest types differed markedly in the climate factors limiting productivity because of differences in tree species and cli-mate condition,and thus differed in responses to climate change.Our results showed that a successful prediction of spatial NPP pat-terns cannot assure that BIOME-BGC can well simulate histori-cal NPP dynamics.Further,a correlation between modeled NPP and tree-ring series cannot assure that the limiting climatic factors for productivity have been correctly identified by the model.Our results suggest the necessity to test the temporal predictions of pro-cess-based models in a more robust way,and further integration of dendrochronology and biogeochemistry modeling may be helpful for this purpose.

Impacts of ontogenetic and altitudinal changes on morphological traits and biomass allocation patterns of Fritillaria unibracteata

Environmental variations and ontogeny may affect plant morphological traits and biomass allocation patterns that are related to the adjustments of plant ecological strategies. We selected 2-, 3-and 4-year-old Fritillaria unibracteata plants to explore the ontogenetic and altitudinal changes that impact their morphological traits(i.e., plant height, single leaf area,and specific leaf area) and biomass allocations [i.e.,biomass allocations of roots, bulbs, leaves, stems, and flowers] at relatively low altitudinal ranges(3400 m to 3600 m asl) and high altitudinal ranges(3600 m to4000 m asl). Our results indicated that plant height,root biomass allocation, and stem biomass allocation significantly increased during the process of individual growth and development, but single leaf area, specific leaf area, bulb biomass allocation, and leaf biomass allocation showed opposite trends.Furthermore, the impacts of altitudinal changes on morphological traits and biomass allocations had no significant differences at low altitude, except for single leaf area of 2-year-old plants. At high altitude,significantly reduced plant height, single leaf area and leaf biomass allocation for the 2-year-old plants,specific leaf area for the 2-and 4-year-old plants, and stem biomass allocation were found along altitudinal gradients. Significantly increased sexual reproductive allocation and relatively stable single leaf area and leaf biomass allocation were also observed for the 3-and 4-year-old plants. In addition, stable specific leaf area for the 3-year-old plants and root biomass allocation were recorded. These results suggested that the adaptive adjustments of alpine plants, in particular F. unibracteata were simultaneously influenced by altitudinal gradients and ontogeny.

Diversity and distribution of soil micro-fungi along an elevation gradient on the north slope of Changbai Mountain

Elevational changes in patterns of diversity are important to understanding of the influence of global changes, yet few studies have addressed the distribution of microorganisms, e.g. soil micro-fungi. We studied the diversity of the forest soil micro-fungi in four vegetation belts along an elevation gradient on the north slope of Changbai Mountain in Changbai National Nature Reserve. The four belts were characterized as coniferous-deciduous mixed forest, coniferous forest, Erman's birch forest, and alpine tundra. We estimated the quantity and distribution of the fungal species in each belt and calculated three indices, viz. Shannon-Wiener diversity (H'), Pielou's evenness (J'), and Margalef's abundance (E), to depict fungal species diversity. A total of 932 strains were recorded and identified, representing 53 genera, and 108 species. Among these, Penicillium, Aspergillus, Trichoderma, Mucor, Rhizopus and Fusarium were the dominant genera. With increasing elevation, the quantity of fungi and values of H', E, and J' gradually declined.

Altitudinal Variation in Digestive Tract Length in Yunnan Pond Frog (Pelophylax pleuraden)

The digestive tract plays an important role in digestion and the acquisition of food energy. Understanding the impact of abiotic environments on digestive tract morphology is especially important for evolution of digestive tract across different environments. Here, we investigated altitudinal variation in digestive tract length in the Yunnan Pond Frog （Pelophylaxpleuraden） across five populations ranging from 1413 m to 1935 m a.s.1, in Ningnan County, Sichuan province in western China. Frogs were collected during the breeding season, from 1-5 June 2012. Our results revealed that females had longer digestive tract and relative digestive tract （i.e. digestive tract length / body size） lengths in com- parison to males, on average, but the differences between them decreased with increasing altitude. Digestive tract and relative digestive tract lengths increased with increasing altitude suggesting that a higher proportion of indigestible ma- terials may be consumed at high-altitude sites and result in a relative increase in digestive tract dimensions.

Altitude pattern of carbon stocks in desert grasslands of an arid land region

For estimating the altitude-distribution pattern of carbon stocks in desert grasslands and analyzing the possible mechanism for this distribution, a detailed study was performed through a series of field vegetation surveys and soil samplings from 90 vegetation plots and 45 soil profiles at 9 sites of the Hexi Corridor region, Northwestern China. Aboveground, belowground, and litter-fall biomass-carbon stocks ranged from 43 to 109, 23 to 64, and 5 to 20 g/m2, with mean values of 80.82,44.91, and 12.15 g/m2, respectively. Soil-carbon stocks varied between 2.88 and 3.98 kg/m2, with a mean value of 3.43 kg/m2 in the 0–100-cm soil layer. Both biomass-and soil-carbon stocks had an increasing tendency corresponding to the altitudinal gradient. A significantly negative correlation was found between soil-carbon stock and mean annual temperature, with further better correlations between soil-and biomass-carbon stocks, and mean annual precipitation. Furthermore, soil carbon was found to be positively correlated with soil-silt and-clay content, and negatively correlated with soil bulk density and the volume percent of gravel. It can be concluded that variations in soil texture and climate condition were the key factors influencing the altitudinal pattern of carbon stocks in this desert-grassland ecosystem. Thus, by using the linear-regression functions between altitude and carbon stocks, approximately 4.18 Tg carbon were predicted from the 1,260 km2 of desert grasslands in the study area.

Plant communities and reproductive phenology in mountainous regions of northern Libya

Within the semi-desert landscape of northern Libya, two sub-humid escarpments occur: Al-Akhdar in the east and Nafusa (Jabal Al-Gharbi) in the west. This study compares plant communities in the two regions, which are along an elevation gradient, in terms of species composition and diversity, frequency of different Raunkiaer life forms, and reproductive phenology. The two regions differed in species composition and life-form frequency between regions and between elevation zones within each region. Patterns were associated with the lower rainfall and lower moisture-holding capacity of soils at Nafusa, resulting in more xeric conditions. Only 13% of species were shared between the two regional landscapes. Species diversity, life-form frequency, and duration of the flowering-fruiting phenophase were all affected by elevation above sea level. The duration of flowering and fruiting in spring and fall was associated with environmental conditions, although there were different thresholds in the two regions. There was both a spring and fall episode of flowering at Nafusa, but only spring flowering at Al-Akhdar. It is anticipated that there will be a gradual shift of plant communities to higher elevations and loss of certain sensitive species in response to ongoing climate change.

C,N,and P Ecological Stoichiometric Characteristics of Two Dominant Mosses in Baotianman Nature Reserve

In order to investigate ecological adaptation mechanism of bryophyte,two dominant mosses Thuidium cymbifolium and Mnium immarginatum in Baotianman Nature Reserve were measured the content of C,N,P and their ratio in bryophyte and soil,and analyzed the relationships of plant and soil ecological stoichiometric characteristics along altitudinal gradients.Results indicate that the content of C,N and P in green tissues of T.cymbifolium and M.immarginatum in Baotianman Nature Reserve was 46.81%-49.09%,0.21%-0.25%,and0.02%-0.08%.Among the different altitudinal gradients,C,N and P displayed significant differences: the significantly different content of C and N were showed in T.cymbifolium,and the content of N and P differed significantly in M.immarginatum.However,only N declined obviously as increasing altitude.In soil,the C,N,N/P and C/P showed an increasing trend with increasing elevation,while the P and C/N along altitudinal gradients exhibited no unified trend.With the increasing in the content C,N of soil,the content C and N of T.cymbifolium raised,while the content C and N of M.immarginatum declined.With the rise in P element of soil,N/P showed different trends between two bryophyte species,the N/P in T.cymbifolium significantly decreased,while N/P in M.immarginatum significantly increased.In addition,mean value of leaf N/P was 8.51,ranking 14-16.These results suggested that the growth of the bryophyte plants in Baotianman Nature Reserve were restricted by N element,and different utilization strategies in soil P element in different bryophyte plants led to differences in ecological stoichiometric characteristics.

Structure and regeneration status of woody species in the Munessa Forest,Southern Ethiopia

This study evaluates the structure and regeneration status of woody species in the Munessa Forest,a dry Afromontane forest in southern Ethiopia.Vegetation data were collected using a systematic sampling method.Density and distribution of seedlings,saplings and mature trees were assessed along an altitudinal gradient using quadrats of different sizes.The number of individuals,frequencies,heights and DBH of species>1 m and DBH>2.5 cm were recorded in altitudinal bands of 100 m.Analysis of the vegetation structure shows that the density of woody species decreases as DBH and height class increases.Basal area of stems with DBH>2.5 cm was 53.4 m^(2)ha^(−1).Population structure and regeneration patterns indicate a significant degradation of the forest due to anthropogenic disturbances.Regeneration was better for less valuable woody species than for species with economic and ecological value.This suggests a discontinuous recruitment of these species due to selective cutting of middle and higher diameter classes.Therefore,enrichment planting of high value,endangered species is necessary to maintain them as part of this forest.There is a need to develop and implement an effective forest management plan for sustainable use of these forest resources.

Altitudinal variation in life-history features of a Qinghai-Tibetan Plateau lizard

Environmental changes along an altitudinal gradient can facilitate the differentiation of life-history features in ectothermic species,but little attention has been devoted to the reciprocal influence of altitude and alpine slope directionality on life-history variation.According to life-history theory,increased environmental stress causes a change in reproductive allocation from number to quality of offspring,as well as a stronger trade-off between size and number of offspring.To clarify the influence of environmental pressures on the life-history features of the Qinghai toad-headed lizard Phrynocephalus vlangalii along an altitudinal cline,we surveyed late pregnant females from 3 populations of low(2,600 m),middle(3,400 m),and high(3,600 m)elevations in the Dangjin Mountain of Gansu,China from July to October 2019,and compared their inter-population differences in maternal body size,reproductive characteristics,offspring growth,and locomotor performance.Because of lower temperatures,higher humidity,and lower light intensity caused by slope aspect and altitude,the middle-altitude region experienced stronger environmental stress than the high-and low-altitude regions.Our results showed that females were larger at middle-and high-altitude sites and smaller at the low-altitude site,following Bergmann’s rule.We also found that females from low-altitude population gave birth earlier than those from the middle and high altitudes.Our results showed a shift in the offspring size-number trade-off of P.vlangalii in response to colder and harsher environments,with lizards from the alpine steppe(i.e.the middle-and high-altitude habitats)producing fewer but larger offspring than those from the warm steppe(i.e.the low-altitude habitat).Low-altitude juveniles grew faster than high-altitude ones,but at the same rates as middle-altitude juveniles.This result demonstrates that the growth of P.vlangalii was associated with temperature and light intensity.Our findings contribute to enhancing our understanding of the altitudinal variation in life-history features of plateau ectotherms and their phenotypic plasticity or local adaptation.

Mountain invasions on the way:are there climatic constraints for the expansion of alien woody species along an elevation gradient in Argentina?

Aims Increasing evidence worldwide indicates that high mountain regions are not immune to invasion by alien plants.Here,we aimed to address whether three major woody invaders of low-mountain areas are constrained to lower altitudes due to climatic restrictions or just by low propagule pressure.We hypothesize that the increasing climatic harshness towards higher altitudes restricts seedling establishment and survival of these woody invaders and thus their potential for altitudinal expansion.Methods The study was carried out in the Sierras Grandes Mountains,Córdoba,central Argentina(32°50′S,64°90′W).We addressed the hypothesis with an experimental approach,dissociating the effect of the environmental gradient from that of propagule pressure,by discarding the influence of seed sources.We translocated seeds of Gleditsia triacanthos L.,Ligustrum lucidum W.T.Aiton.and Pyracantha angustifolia(Franch.)C.K.Schneid.along the altitudinal gradient(from 900 to 2700 m asl).Seven sites were selected along the altitudinal gradient,spaced every 200-400 m.Three plots(4×4 m)were selected within each altitudinal site and excluded from livestock;100 seeds of each species were sown within each plot(6300 seeds in total).Seedling emergence and survival was monitored during two growing seasons and soil temperature and moisture was recorded as well.The field experiment was complemented with lab assays.Important Findings Climate along this altitudinal gradient might be least restrictive at mid elevations,as a result of the intersection between opposite soil temperature and moisture gradients.Sown seeds germinated along the whole altitudinal gradient and seedlings successfully established and over-wintered well above their current altitudinal distribution(up to 2200 m for Ligustrum and 2400 m for Gleditsia and Pyracantha).Additional lab assays confirmed field patterns and gave some insights into contrasting regeneration strategies between these invaders that might help to overcome stochastic environmental constraints in the germination stage.Overall,seedlings of three major woody invaders of low-mountain woodlands can establish and survive at higher elevations than their current distribution.In contrast to natives,they seem to be broad climate tolerators,rather than specialized stress tolerators,capable of germinating and growing across a wide elevational range.While long-term experiments might be necessary to fully address the potentials for altitudinal expansion,out results on early lifecycle stage suggest that the invaders studied here would have mostly a dispersal barrier rather than a climate barrier to establish in the upper belt of the Sierras Grandes.

Relationship between clade age and temperature for angiosperm tree species in forest communities along an elevational gradient in tropical Asia

Aims The tropical conservatism hypothesis(TCH)links environmental tolerance,diversification,dispersal and evolutionary history in explaining why warm,wet tropical regions harbor more species than colder,drier regions.The TCH is considered as a dominant explanation for broad-scale patterns of species richness across the globe,such as the latitudinal diversity gradient.At its core,the TCH predicts a positive relationship between clade age and tempera-ture.Here,I test this prediction using a data set of angiosperm tree assemblages from Malesia.Methods I assembled an altitudinal gradient of 15 communities of angio-sperm trees.I calculated the mean family age(MFA)of tree species for each community.I used ordinary regression analysis and spatial autoregression analysis to determine the relationships of species richness and MFA with elevation,temperature and precipitation.I used correlation analysis to assess relationships between paired variables.Important Findings MFA is negatively correlated with tree species richness,and increases with elevation and decreases with temperature for the alti-tudinal gradient.MFA remains significantly increasing with decreas-ing temperature along the altitudinal gradient after accounting for spatial autocorrelation in a species-ordination space.The negative relationship between clade age and temperature along the altitudi-nal gradient in Malesia is contrary to the TCH.

祁连山中部不同海拔青海云杉径向生长对升温的响应分异

Understanding the radial growth trends of trees and their response to recent warming along elevation gradients is crucial for assessing how forests will be impacted by future climate change.Here,we collected 242 tree-ring cores from five plots across the Qinghai spruce(Picea crassifolia Kom.)forest belt(2600–3350 m a.s.l.)in the central Qilian Mountains,Northwest China,to study trends in the radial growth of trees and their response to climate factors with variable elevation.All the sampled P.crassifolia chronologies showed an increasing trend in the radial growth of trees at higher altitudes(3000–3350 m),whereas the radial growth of trees at lower altitudes(2600–2800 m)has decreased in recent decades.The radial growth of trees was limited by precipitation at lower elevations(L,ML),but mainly by temperature at higher elevation sites(MH,H,TL).Climate warming has caused an unprecedented increase in the radial growth of P.crassifolia at higher elevations.Our results suggest that ongoing climate warming is beneficial to forest ecosystems at high elevations but restricts the growth of forest ecosystems at low elevations.

Changes in reproductive investment with altitude in an alpine plant

Aims In perennial species,the allocation of resources to reproduction results in a reduction of allocation to vegetative growth and,therefore,impacts future reproductive success.As a consequence,variation in this trade-off is among the most important driving forces in the life-history evolution of perennial plants and can lead to locally adapted genotypes.In addition to genetic variation,phenotypic plasticity might also contribute to local adaptation of plants to local conditions by mediating changes in reproductive allocation.Knowledge on the importance of genetic and environmental effects on the tradeoff between reproduction and vegetative growth is therefore essential to understand how plants may respond to environmental changes.Methods We conducted a transplant experiment along an altitudinal gradient from 425to1921 min the frontrange of the Western Alps of Switzerland to assess the influence of both altitudinal origin of populations and altitude of growing site on growth,reproductive investment and local adaptation in Poa alpina.Important findings In our study,the investment in reproduction increased with plant size.Plant growth and the relative importance of reproductive investment decreased in populations originating from higher altitudes compared to populations originating from lower altitudes.The changes in reproductive investment were mainly explained by differences in plant size.In contrast to genetic effects,phenotypic plasticity of all traits measured was low and not related to altitude.As a result,the population from the lowest altitude of origin performed best at all sites.Our results indicate that in P.alpina genetic differences in growth and reproductive investment are related to local conditions affecting growth,i.e.interspecific competition and soil moisture content.

Patterns of plant diversity at high altitudes on the Qinghai-Tibetan Plateau

To describe the biodiversity patterns of plants along an altitudinal gradient on the Qinghai-Tibetan Plateau and to clarify the bias in plant specimen records at high altitude.Methods We conducted a large-scale investigation of vegetation at a wide range of altitudes,focusing on a high-altitudinal range(3200-5200 m)at different locations on the Qinghai-Tibetan Plateau.We then compared the altitudinal distribution of plant species obtained from our field investigation with that in plant specimen records from published sources and an online database.Important Findings Our data provide evidence that altitude plays a large role in regulating species composition on the Qinghai-Tibetan Plateau.We could not,however,detect a clear relationship between altitude and species richness,although a weak monotonically increasing trend of richness was detected with increasing altitude.According to specimen records,most species have been sampled at a wide range of altitudes,and the average range of 145 species is>2000 m.Despite this wide range,more than half of the species we observed were at higher altitudes than the specimen records indicate.High-altitude areas have probably been so poorly sampled that only a small fraction of the resident species has been recorded.This study clearly shows the regional bias of specimen records in the Qinghai-Tibetan Plateau.