Mountain Tree Research Articles

Elevational differentiation in metabolic cold stress responses of an endemic mountain tree

The decline of mountain forests under global change is alarming and conservation is challenged by the need to assemble populations able to deal with the predicted environmental shifts. Assessing intraspecific differentiation in stress susceptibility of tree species along elevational gradients is crucial to identify adequate genetic sources for mountain forest restoration. Here, we assessed injury and metabolic responses across cold stress intensity gradients in low and high elevation populations of the endangered mountain tree Polylepis australis. We hypothesized that populations from high elevational origins will show weaker increases of injury and more pronounced metabolic responses with rising cold stress intensity than low elevation populations. The expected differentiation among elevational origins was not observed for cold stress injury, but for metabolic stress responses. Plants responded to cold with enhanced concentrations of sugars, organic acids, amines and specialized metabolites with freezing point depressing, cryo-protective and anti-oxidative properties. As predicted, these responses were more pronounced and partially increased more strongly with stress intensity in high than low elevation populations, indicating local adaptation to a higher frequency and intensity of cold events at high elevations. We discuss the power of metabolomics approaches in unravelling intraspecific differentiation in tree stress resistance across small geographic scales as well as implications for future research on the evolution of cross-resistance to multiple stressors and for forest restoration.

Effects of altitude, land use and microsites on early life performance of a high mountain tree: Insights from an in situ sowing experiment

AbstractAimUnderstanding the forces that drive range shifts in forest landscapes is imperative for predicting species distributions under anthropogenic climate and land use change. However, empirical studies exploring how these components jointly influence critical early life stages of mountain tree species across environmental gradients are scarce. We used the high mountain tree Polylepis australis as model species to investigate the relative importance of altitude and associated climatic conditions, land use for livestock and microsite characteristics on early life performance.LocationCórdoba Sierras, central Argentina.MethodsWe set up an extensive in situ sowing experiment with a robust split‐plot design that integrated spatial scales ranging from 0.4 m2 subplots at the microsite level (associated with vegetative and microtopographic structures), to livestock exclosure and enclosure plots of several hectares, to an altitudinal gradient of 1,000 m. Components of early life performance were monitored across two subsequent growing seasons.ResultsMicrosite characteristics played a fundamental role in P. australis establishment, whereby interactions with altitude and/or land use suggested alternate mechanisms: facilitation (likely reduced desiccation) dominated at low altitude while at high altitude, abiotic stress (likely intensive frost and radiation) overruled any microsite effects. At mid‐altitude, benefits of competition release prevailed over facilitation and microsite effects gained importance under livestock presence. Inconsistencies between pre‐ and post‐emergence responses illustrated potential trade‐offs between beneficial and detrimental effects of microsite conditions upon performance throughout early life: a favourable location for seeds may abruptly turn adverse for seedlings.Main conclusionsWe unravel how changes in altitude, anthropogenic disturbances and microsite characteristics jointly modulate P. australis performance across stages of early establishment. Such information is fundamental when categorizing specific microhabitats as “safe sites” for tree regeneration especially in mountain environments with high spatio‐temporal heterogeneity.

Accelerating upward treeline shift in the Altai Mountains under last-century climate change

Treeline shift and tree growth often respond to climatic changes and it is critical to identify and quantify their dynamics. Some regions are particularly sensitive to climate change and the Altai Mountains, located in Central and East Asia, are showing unequivocal signs. The mean annual temperature in the area has increased by 1.3–1.7 °C in the last century. As this mountain range has ancient and protected forests on alpine slopes, we focus on determining the treeline structure and dynamics. We integrated in situ fine-scale allometric data with analyses from dendrochronological samples, high-resolution 3D drone photos and new satellite images to study the dynamics and underlying causal mechanisms of any treeline movement and growth changes in a remote preserved forest at the Aktru Research Station in the Altai Mountain. We show that temperature increase has a negative effect on mountain tree growth. In contrast, only younger trees grow at higher altitudes and we document a relatively fast upward shift of the treeline. During the last 52 years, treeline moved about 150 m upward and the rate of movement accelerated until recently. Before the 1950s, it never shifted over 2150–2200 m a.s.l. We suggest that a continuous upward expansion of the treeline would be at the expense of meadow and shrub species and radically change this high-mountain ecosystem with its endemic flora. This documented treeline shift represents clear evidence of the increased velocity of climate change during the last century.

Past plant diversity changes and mountain tree species conservation

Past plant diversity changes and mountain tree species conservation

Elevation modulates the phenotypic responses to light of four co-occurring Pyrenean forest tree species

Elevation markedly modified the species-specific phenotypic responses of trees to light. The effects from elevation mostly occurred at organ level (SLA) for the montane species, but at whole-plant level (allocation traits) for the subalpine ones. The subalpine species allocate more carbon to roots under closed canopies at low elevation. Contrary to expectations, most species displayed smaller specific leaf area at high elevation. The most drought-intolerant species was more severely affected by drought under shade than in open microsites. Understanding the phenotypic responses of mountain tree species to different levels of local irradiance can be of critical importance for elucidating their capacity to relocate above their current distributional limit in response to environmental changes. To evaluate whether the response of different co-occurring forest tree species to local irradiance varies when they are growing at various elevations or beyond their current distributional limit. Seedlings of four tree species (Betula pendula Roth., Pinus sylvestris L., Abies alba Mill., and Pinus uncinata Ram. ex DC.) were planted under different irradiance levels (forest understory vs natural gaps) and at various elevation (montane–subalpine ecotone and subalpine belt). After four growing seasons, 48 plants per species were excavated to assess allocational (biomass distribution) and morphological (specific leaf area) traits. Midday leaf water potential was recorded during a period of intense drought. The subalpine species (A. alba and P. uncinata) increased their allocation to the root system at low elevation and under dense canopy. We observed constant or higher SLA in all species when they develop in the subalpine belt. B. pendula was affected more severely by drought at low elevations and under shade than in open microsites. We found marked species-specific phenotypic variability of tree seedlings to increasing irradiance, with these responses modulated by the elevation at which the trees were growing.

Aridity and competition drive fire resistance trait covariation in mountain trees

AbstractFire resistance traits drive tree species composition in surface‐fire ecosystems, but how they covary at different scales of variation and with the environment is not well documented. We assessed the covariation of bark thickness (BT), tree height, and crown base‐to‐height ratio across Alpine forests, after accounting for the effects of tree diameter and competition for light on individual trait variation. Traits consistently correlated across individuals and communities, although the variance of BT mainly occurred among species, whereas crown elevation traits varied mainly within species. Aridity, temperature, and competition contributed to explain the variation of fire resistance traits among and within species, driving a trade‐off between fire resistance and the ability to compete for light. Thick‐barked species (fire‐tolerant) that self‐prune their lower branches (flame‐avoiders) dominated the most fire‐prone and flammable communities in sub‐Mediterranean southern Alps, whereas thin‐barked tree species that grow tall (competition for light) dominated the least fire‐prone communities in the northern Alps. Our findings suggest a long‐term interaction between mountain tree species and fire regime. Higher allocation to trunk elongation occurs in moist and shade environments, while higher allocation to thicken the bark and distancing the crown base from surface fuels occurs in open‐canopy, dry forests where fire spreads with higher intensity.

Comparison of budburst phenology trends and precision among participants in a citizen science program.

Quantifying shifts in plant phenology in response to climate change represents an ongoing challenge, particularly in mountain ecosystems. Because climate change and phenological responses vary in space and time, we need long-term observations collected at a broad spatial scale. While data collection by volunteers is a promising approach to achieve this goal, one major concern with citizen science programs is the quality and reliability of data. Using a citizen science program (Phenoclim) carried out in the western European Alps, the goals of this study were to analyze (1) factors influencing participant retention rates, (2) the efficacy of a citizen science program for detecting temporal changes in the phenology of mountain trees, (3) differences in budburst date trends among different observer categories, and (4) the precision of trends quantified by different categories of participants. We used 12years of annual tree phenology measurements recorded by volunteers (schools and private individuals) and professionals within the Phenoclim program. We found decadal-scale shifts in budburst date consistent with the results from other studies, including significant advances in budburst date for the common birch and European ash (- 4.0 and - 6.5days per decade respectively). In addition, for three of six species, volunteers and professionals detected consistent directional trends. Finally, we show how differences in precision among the categories of participants are determined by the number of years of participation in the program, the number of sites surveyed, and the variability in trends among sites. Overall, our results suggest that participants with a wide range of backgrounds are capable of collecting data that can significantly contribute to the study of the impacts of climate change on mountain plant phenology.

Performance Evaluation of Carbon Black Nano-Particle Reinforced Asphalt Mixture

Applications of nanotechnology in the pavement industry have increased rapidly during the last decade in order to enhance a pavement’s sustainability and durability. Conventional asphalt binder generally does not provide sufficient resistance against rutting at high temperatures. Carbon black nano-particles (CBNPs, produced by perennial mountain trees’ carbonization) were mixed into the performance grade (PG) 58 asphalt binder in this study. Conventional asphalt binder tests (penetration, ductility and softening point), frequency sweep, performance grading, and bitumen bond strength tests were conducted to study the enhancement in the properties of asphalt binder. Dynamic modulus and wheel tracking tests were also performed to investigate the effect of CBNPs on asphalt mixture properties. Experimental results demonstrated that preferred dosage of CBNPs in asphalt is 10% by weight of the bitumen. Results of scanning electron microscopy (SEM) and storage stability tests validated homogenous and stable dispersion of CBNPs in the asphalt binder. Asphalt mixtures became stiffer and resistant to rutting at high temperatures by addition of CBNPs in asphalt binder. Significant improvement in bitumen aggregate bond strength was also observed by incorporating CBNPs. It is concluded that CBNPs can be used to effectively enhance the high-temperature performance and consequently the sustainability of flexible pavements.

Higher potential fire intensity at the dry range margins of European mountain trees

AbstractAimPotential fire intensity (PFI) is among the main drivers of fire–vegetation interactions, but how it varies across species ranges is unknown. We test whether PFI and crown fire likelihood (CFL) increase preferentially towards the warm/dry range margins of mountain trees.LocationThe western Alps.MethodsWe analysed PFI and CFL patterns across the environmental niches of major mountain forest tree species, using field observation data of surface fuels with fire simulations. Empirical relationships between PFI and climate and vegetation structure were identified in communities sampled for surface fuels, and then used to predict PFI in national forest inventory plots.ResultsSimulations indicate that autumn drought, spring precipitation, tree cover and tree basal area drove the variation in understorey fuels among communities, leading to different PFI among and within the environmental ranges of mountain tree species. PFI was consistently higher in the open‐canopy, dry margins of dominant tree species. The highest PFI values were found in the sub‐Mediterranean and subalpine forests in conjunction with higher CFL.Main conclusionsMountain trees are exposed to higher PFI and CFL at their dry range margins, suggesting higher potential fire impacts at their rear distribution edges. Moist montane species (Fagus sylvatica, Abies alba, Picea abies) are exposed to surface fires of lower intensities than sub‐Mediterranean (Quercus pubescens, Pinus nigra, P. sylvestris) and subalpine species (Larix decidua, P. uncinata, P. cembra) which may both experience higher likelihood of crown fires at their dry and flammable margins.

Geographic patterns and environmental drivers of seed traits of a relict tree species

Seed traits related to recruitment can directly affect plant fitness and persistence. Phenotypic variability in seed traits among populations could increase species resilience and reduce the risk of extinction under climate change. However, seed trait variations along geographic gradients of relict mountain tree species remain poorly explored despite their vulnerability to environmental changes. Here, we collected seeds of Euptelea pleiospermum from 18 populations across its natural distribution in China, measured seed morphology and seed nutrients, and performed a germination test. We investigated geographic patterns of seed traits and analyzed the relationships between environmental factors and seed traits. We also analyzed the relationships between seed intrinsic attributes and seed germination percentage. In addition, we explored the direct and indirect effects of climatic and edaphic variables on seed germination percentage. We found substantial variation in seed traits of this species among populations. Seed mass decreased from low to high latitude, and seed size (length and width) decreased with longitude from west to east. Seed germination timing increased from low to high altitude. Temperature and soil phosphorus determined the geographic variation of seed traits. Seed mass and seed nitrogen had positive effects on seed germination percentage. Seed intrinsic attributes, rather than maternal environmental factors, were the dominant drivers of the variability in seed germination percentage. However, maternal environmental variables could indirectly affect the seed germination percentage through their effects on seed morphology and nutrients. These results demonstrate that among-population seed trait variations are mainly driven by climatic variables and soil nutrients, and indicate that climate warming is likely to alter seed germination patterns by shifting seed intrinsic attributes. Our study provides insight into how mountain tree species regulate seed traits and germination time to adapt to heterogeneous environments and improves our power to predict how relict plants may respond to climate change.

Onomatopoeia, Interiority, and Incorporation

Onomatopoeia, Interiority, and Incorporation1 Matthew Rowlinson (bio) 1 A largely unnoticed volume published in 1832 appears to have TV been the first work on birds to include nonce-transcriptions of their calls as an aid to identification. This adaptation of an ancient poetic technique for the purposes of natural history and pedagogy remains familiar today in birders’ field guides and in stories and verse for children.2 As well as seeing the first syllabic representation of birdsong in a work of natural history, the first half of the nineteenth century was also the period when teaching animal sounds became a function of children’s literature.3 The 1832 volume was titled The Minstrelsy of the Woods, or Sketches and Songs Connected with the Natural History of . . . British and Foreign Birds; it combines [End Page 429] the two genres, since it is explicitly addressed to young readers, both in its dedication to the anonymous author’s “beloved young relatives” and in the introductory poem “To my Brother’s Children.” The book’s introduction states its debt to Thomas Bewick’s History of British Birds (1797–1804) and to Georges Cuvier’s The Animal Kingdom (published 1807 as Le Règne Animal). Cuvier and Bewick are indeed major sources for the Minstrelsy’s descriptions of birds’ appearance and habit; it also draws from them fundamental principles of organization. The basic object of study in the Minstrelsy, as in Bewick and Cuvier, is the species, and the work’s aim is to teach its readers to identify the species of birds they encounter in the wild. Its organization is thus modeled on that which Bewick made standard for field guides to this day, with the work being divided into sections grouping birds by families, and within these sections a chapter devoted to each species. To the taxonomic markers of habit, plumage, and so forth that it adopts from Bewick and Cuvier, the Minstrelsy adds phonetic transcriptions of birdcalls. In some cases these transcriptions are traditional, as when the cry of the tawny owl is described as “well imitated by the syllables tee-whit or too-whit, and the hollow shuddering kind of note too-whoo.”4 The book’s title points two ways; as well as a handbook on identifying birds by their song, it is also a miscellany of poetry about birds. While it includes long passages from other poets including James Thomson and Charlotte Smith, much of the Minstrelsy’s poetry is original. Each of the birds it treats has a poem dedicated to it, in many of which the birds speak for themselves, with the syllabic transcription of their songs making a refrain. Thus, “The Song of the Wood-Grouse”: You must look for meOn my mountain tree,Where the hardy pine uncultured grows,Where the foaming torrent wildly flows,There look for me,On my mountain tree,With my clarion note he-de-he-de-he.5 There may be earlier texts to use phonetic transcriptions of birdcalls as species markers, though I have not found any; I suggest in any case that in its assumption that animals of a given species always say the same thing, and its setting of their utterance in verse, Minstrelsy is an artifact of its historical moment. [End Page 430] 2 We know the poetic technique employed by the Minstrelsy as onomatopoeia, and this essay will consider two different kinds of animal onomatopoeia in Romantic poetry. In the examples to be discussed, I will argue that onomatopoeia is treated as a poetic error, incorporating animal utterance in the poem only to reject it, or to make the animal itself an object of sacrifice. Onomatopoeia’s foundational theorist was Quintilian, in whose late first century Institutio Oratoria the term refers—as its etymology implies—to any new creation of a word. The examples Quintilian gives, however, are all of what would be termed onomatopoeias in our time, words coined to refer to a sound while also mimicking it: they are “mugitus, lowing, sibilus, a hiss, and murmur.”6 For the Elizabethan rhetorician George Puttenham, onomatopoeia is “the New namer”;7 Puttenham is explicit that the newly-minted word should be “consonant” to...

Species interactions weakly modify climate‐induced tree co‐occurrence patterns

AbstractAimsSpecies distributions are hypothesized to be underlain by a complex association of processes that span multiple spatial scales including biotic interactions, dispersal limitation, fine‐scale resource gradients and climate. Species disequilibrium with climate may reflect the effects of non‐climatic processes on species distributions, yet distribution models have rarely directly considered non‐climatic processes. Here, we use a Joint Species Distribution Model (JSDM) to investigate the influence of non‐climatic factors on species co‐occurrence patterns and to directly quantify the relative influences of climate and alternative processes that may generate correlated responses in species distributions, such as species interactions, on tree co‐occurrence patterns.LocationUS Rocky Mountains.MethodsWe apply a Bayesian JSDM to simultaneously model the co‐occurrence patterns of ten dominant tree species across the Rocky Mountains, and evaluate climatic and residual correlations from the fitted model to determine the relative contribution of each component to observed co‐occurrence patterns. We also evaluate predictions generated from the fitted model relative to a single‐species modelling approach.ResultsFor most species, correlation due to climate covariates exceeded residual correlation, indicating an overriding influence of broad‐scale climate on co‐occurrence patterns. Accounting for covariance among species did not significantly improve predictions relative to a single‐species approach, providing limited evidence for a strong independent influence of species interactions on distribution patterns.ConclusionsOverall, our findings indicate that climate is an important driver of regional biodiversity patterns and that interactions between dominant tree species contribute little to explain species co‐occurrence patterns among Rocky Mountain trees.

A Study on Awareness of Mind and Heart(心) in Ox mountain's tree(牛山之木) of Sim-Gyung-Bu-Ju(心經附註)

A Study on Awareness of Mind and Heart(心) in Ox mountain's tree(牛山之木) of Sim-Gyung-Bu-Ju(心經附註)

The Ideas and Methods: Realization of Modern Artists of Kazakhstan in Creative Works through Colour Distribution of Paintings - Muratbayev

The article features color combination and painting techniques of the Kazakh artists, such as Muratbayev, Muratbayev, Bube Belly, Akzhan Fbdieva and Nartay Zhardemov. Realization of color combinations can be accomplished through the following way: all of creative works/images, which come together in tone and color correlations, are proportional to visual image; the main integrity of fine art works is only the image in the soul of the artist - “work in soul”. The main part of Art works/paintings is being in harmony within themselves. Hence, the artists of modern era in Kazakhstan have been able to use harmony techniques in their art works. A person is in harmony with nature. It can be seen from mountain shapes, valleys, trees and grasses, animals and birds, which are perceptive to human brain and human eyes. Crucial factors have been rhythm and symmetry, the eternal harmony of creators. The universal manifestation of rhythm and symmetry leads to single order of all that are present in nature. 21st century’s Art of Independent Kazakhstan is expressed through аesthetics, language, implements of the high visual art. Art of Independent Kazakhstan is covering continuity of cultural, political, historical signs of the modern art. Therefore, paintings of Independent Kazakhstan are unique in their structure. They have been developed for 25 years in correlation with other art forms, improving the new directions, as well as forms and genres. The art works and paintings of Independent Kazakhstan form their own aesthetic language, specific modern methods, national traditions and particular art language of the graphic works, as well as the new directions of Kazakhstan’s paintings that have resulted from certain specific factors. That is why it is important to understand the main directions of Visual Art of Independent Kazakhstan’s artists, along with the color combination and painting techniques that they have used. Hence, that is what this paper is addressing.

Genetic evidence for central‐marginal hypothesis in a Cenozoic relict tree species across its distribution in China

AbstractAimThis study tests predictions of the central‐marginal (C‐M) hypothesis using geographical patterns of genetic variation in a Cenozoic relict tree species Euptelea pleiospermum. Additionally, we explore the extent to which post‐glacial recolonization and landscape barriers created by topographical heterogeneity shape spatial genetic variation.LocationSouth‐west and central subtropical China.MethodsUsing microsatellite data of 678 individuals from 21 populations, we documented geographical patterns of genetic diversity and population genetic structure, supplemented with current and past (Last Glacial Maximum, LGM) distributions based on species distribution models (SDMs). Genetic structure was determined by non‐spatial and spatially sensitive Bayesian clustering, analysis of molecular variance, barrier analysis and a multivariate population graphing approach. We also examined both historical and contemporary gene flow.ResultsGenetic diversity significantly declined with distance from centre and showed unimodal patterns along both latitude and longitude. The C‐M pattern of genetic diversity along latitudinal gradient is high‐latitude‐skewed, with the peak at higher portion of the species' latitudinal extent. The Sichuan Basin divided individuals into south and north clusters, whereas the Qinba Mountains did not. The general shape of the predicted distribution during the LGM is strongly similar with that of current distribution, except the Sichuan Basin.Main conclusionsOur study provides genetic evidence for the C‐M hypothesis in a Cenozoic relict tree species across its distribution in China. The Sichuan Basin, rather than the Qinba Mountains, acts as dispersal barrier for a mountain tree species. Our results suggest that in situ refugia were maintained across southwest and central China during the LGM. The slight post‐glacial northward expansion and asymmetrical south–north historical‐gene flow did not result in a low‐latitude‐skewed C‐M pattern of genetic diversity. Instead, complex topography in combination with the C‐M dispersal dynamics shaped the latitudinal pattern of genetic diversity.

Effect of the Aegean Sea barrier between Europe and Asia on differentiation inJuniperus drupacea(Cupressaceae)

Juniperus drupacea is an eastern Mediterranean mountain tree with a disjunct geographical range. We hypothesized that this disjunct occurrence (the Peloponnese in Europe and the Taurus and Lebanon Mountains in Asia) should be reflected in the patterns of genetic and morphological diversity and differentiation. Nuclear microsatellite markers (nSSR) and biometric variables of the cones and seeds were examined on material sampled from four populations in Europe and eight in Asia. The Asian populations were characterized by a higher level of genetic diversity than the European populations. The genetic differentiation among populations was moderate but significant (FST = 0.101, P < 0.001). According to the clustering performed with BAPS, six genetically and geographically groups of populations were found: I and II from the Peloponnese; III from the Taurus Mountains; IV and V from the Anti-Taurus Mountains; and VI from the Lebanon Mountains. The level of genetic differentiation among these six groups (4.30%, P = 0.012) probably reflects long-lasting genetic isolation during the Pleistocene, as limited genetic admixture was found. In accordance with genetic analysis, the biometric investigations indicated a high level of morphological divergence between the European and Asian populations of the species, with further differentiation between the populations from the Taurus and Lebanon Mountains.

Land‐use legacies rather than climate change are driving the recent upward shift of the mountain tree line in the Pyrenees

AbstractAimTo assess the effects of climate change, past land uses and physiography on the current position of the tree line in the Catalan Pyrenees and its dynamics between 1956 and 2006.LocationMore than 1000 linear kilometres of sub‐alpine tree line in the Catalan Pyrenees (north‐east Spain)MethodsUsing aerial photographs and supervised classification, we reclassified the images into a binary raster with ‘tree’ and ‘non‐tree’ values, and determined canopy cover in 1956 and 2006. We then determined the change in position of the tree line between 1956 and 2006 based on changes in forest cover. We used the distance from the position of the tree line in 1956 to the theoretical potential tree line – determined from interpretation of aerial photographs, identifying the highest old remnants of forest for homogeneous areas of the landscape in terms of bioclimatic conditions, bedrock, landform and exposure – as a surrogate of intensity of past land uses.ResultsOur analyses showed that the Pyrenean tree line has moved upwards on average almost 40 m (mean advance ± SE: 35.3 ± 0.5 m, P &lt; 0.001), although in most cases it has remained unchanged (61.8%) or advanced moderately, i.e. between 25 and 100 m (23.7%); only 9.2% of the locations have advanced more than 100 m. Upward shifts of the tree line were significantly larger in locations heavily modified in the past by anthropogenic disturbance (mean advance 50.8 ± 1.1 m) compared with near natural tree line locations (19.7 ± 0.8 m, P &lt; 0.001), where the mean displacement was much lower than expected and was not related to changes in temperature along the study period.Main conclusionsOur results stress the impact of the cessation of human activity in driving forest dynamics at the tree line in the Catalan Pyrenees, and reveal a very low or even negligible signal of climate change in the study area.

Використання діелектричних показників для визначення життєвого стану дерев в’яза шорсткого

Встановлено, що важливими критеріями відбору здорових, не уражених голландською хворобою (Graphium ulmi Schwarz) особин в'яза, поряд з морфологічними ознаками, є діелектричні показники – імпеданс і поляризаційна ємність. Між категоріями життєвого стану дерев в'яза та діелектричними показниками виявлено тісний кореляційний зв'язок (r2=0,88-0,98). Із погіршенням життєвого стану дерев в’яза величина поляризаційної ємності знижується, а величина імпедансу зростає. Загалом потрібний комплексний підхід до визначення життєвого стану дерев в'яза, який грунтується на використанні як морфологічних, так і діелектричних показників.

Facilitation and edge effects influence vegetation regeneration in old‐fields at the tropical Andean forest line

AbstractQuestionsDo local plant–plant interactions and facilitation play an important role in vegetation dynamics after disturbance in the high tropical Andes? In particular, does the dominant shrub Baccharis prunifolia have an effect on microclimate and local vegetation structure within old‐fields at the upper forest line? Does distance from the border of the surrounding forests also influence community structure within fallow plots? Is there an interaction between facilitation and edge effects on vegetation regeneration?LocationGavidia Valley, Sierra Nevada de Mérida, Venezuela.MethodsPlant cover, species richness and community structure were compared in circular micro‐plots placed under the canopy of B. prunifolia shrubs and in open areas (12 micro‐plots in each case) both near and far from the forest border within two 10–12 yr successional plots at 3400 m a.s.l. (a total of 96 micro‐plots). Additionally, topsoil temperature was monitored for 1 mo in the four situations under study.ResultsAverage and maximum temperature and temperature amplitudes were lower under the canopy of B. prunifolia shrubs than in open areas; this effect being more marked far from the forest edge. Species richness, vegetation cover and the density of dominant forest trees were higher under the shrubs’ canopy than in the inter‐shrub spaces. The proximity to the edge of the surrounding forest also had a positive effect on species richness, with no significant interaction with the local sampling situation (under shrub vs outside).ConclusionsOur results suggest that both facilitation and edge effects influence the effectiveness of vegetation regeneration within old‐fields in the high tropical Andes. Consequently, these processes should be considered for interpreting vegetation dynamics in environmental change scenarios at the tropical mountain tree line and for the design of ecological restoration strategies in these high‐diversity ecotones, which have been subjected to large‐scale anthropogenic transformations in recent decades.

Survival vs. growth trade-off in early recruitment challenges global warming impacts on Mediterranean mountain trees

Climate change is expected to alter the geographic distribution of many plant species worldwide. However, there is still no clear evidence showing a generalised direction and magnitude of these distribution shifts. Here, we have surveyed, in nine mountainous regions in Spain, an array of tree species along entire elevational ranges, as surrogates of their global climatic ranges, to test for elevational shifts towards cooler locations. We analysed the distribution recruitment patterns of five dominant tree species, recording the abundance and measuring the primary growth of juveniles in 306 plots. Three of the species have a temperate-boreal distribution with populations at their southern edge in the Mediterranean mountain ranges: Pinus sylvestris, Pinus uncinata and Fagus sylvatica; and the other two species have a Mediterranean distribution: Quercus ilex and Pinus nigra. Despite the contrasting phylogenies and biogeographies, we identified a similar pattern in recruitment abundance across species, with an asymmetric distribution of juveniles (more recruits in the middle-upper elevation of their range), but higher annual growths at lower elevations. This survival-growth trade-off at the early recruitment stage may potentially counterbalance at population level the negative effect of global warming on recruit survival at the lower edge of species ranges. These findings suggest a demographic stabilisation process at the early recruitment stage of these tree species, and highlight the importance of considering the different demographic stages across the whole climatic range to understand the effects that climate change may exert on species distributions and population dynamics.