Tree Age Structure Research Articles

Shifts in taxonomical and functional structure of ectomycorrhizal fungal community of Scots pine (Pinus sylvestris L.) underpinned by partner tree ageing

Ectomycorrhizal (ECM) fungi are crucial in the functioning of most forest ecosystems. Increased understanding of ECM symbiosis has led to numerous advancements in environment protection and forestry. The ECM fungi are a diverse group, both phylogenetically and functionally. Research covering their community structure on distinct sites shows that the presence of certain taxa depends on particular stand traits, such as tree species and age structure. Disturbances to the local habitat, ranging from forest fires to planned management, have also been shown to impact which fungal species are present. This study focuses on the dynamics of changes within the taxonomic and functional structure of the ECM fungal community as a response to host tree (Scots pines (Pinus sylvestris L.)) aging and how this dynamic is affected by forest management. While no explicit difference in ECM fungal species diversity between stands of different age was observed, the present taxa contributing to this diversity varied. Along the pine age gradient, some ECM fungal taxa were gradually being replaced with others. Additionally, a shift in functionality (i.e. exploration type community structure) was observed. In older forests, ECM fungal species of shorter distance exploration types became more prevalent. While forest management via thinning affected this process, the effect was not persistent.

Street Trees in a Chinese Forest City: Structure, Benefits and Costs

Street trees provide critical ecosystem services and economic benefits that are often disregarded, due to their unknown monetary value. This study analyzed the structural characteristics of Dalian’s street trees and estimated the monetary value of structural and functional benefits by i-Tree Streets. Dalian’s street trees encompassed 28 species and were dominated by Ginkgo biloba, Platanus acerifolia and Sophora japonica, comprising 64.1% of a total of 57,699 trees. The age structure of street trees was distributed somewhat unevenly, with 18% young trees, 56% maturing trees, 25% mature trees and 1% old trees. These trees provide annual functional benefits valued at US$4.9 million and delivered a benefit-cost ratio of 3.2:1. The largest values associated with energy savings and property value were $1.7 million ($29/tree) and $1.5 million ($25/tree), respectively. The net carbon reduction benefits were valued at $935,205 ($16/tree). Smaller benefits resulted from air quality improvement ($381,088 or $7/tree) and stormwater runoff ($459,457 or $8/tree). The structural benefits were valued at $130 million, with the value of $4.5 million for carbon storage. These findings suggested that the benefits produced by street trees were worth the management costs. Our results provide a thorough understanding of the benefits produced by street trees to policy-makers and managers, and help them make informed policies to maximize and sustain the flow of benefits.

Warming-induced upward migration of the alpine treeline in the Changbai Mountains, northeast China.

Treeline responses to environmental changes describe an important phenomenon in global change research. Often conflicting results and generally too short observations are, however, still challenging our understanding of climate-induced treeline dynamics. Here, we use a state-of-the-art dendroecological approach to reconstruct long-term changes in the position of the alpine treeline in relation to air temperature at two sides in the Changbai Mountains in northeast China. Over the past 160years, the treeline increased by around 80m, a process that can be divided into three phases of different rates and drives. The first phase was mainly influenced by vegetation recovery after an eruption of the Tianchi volcano in 1702. The slowly upward shift in the second phase was consistent with the slowly increasing temperature. The last phase coincided with rapid warming since 1985, and shows with 33m per 1°C, the most intense upward shift. The spatial distribution and age structure of trees beyond the current treeline confirm the latest, warming-induced upward shift. Our results suggest that the alpine treeline will continue to rise, and that the alpine tundra may disappear if temperatures will increase further. This study not only enhances mechanistic understanding of long-term treeline dynamics, but also highlights the effects of rising temperatures on high-elevation vegetation dynamics.

Участь деревних інвазійних видів рослин у формуванні насаджень паркової зони міста Дніпро

A comparative analysis of the green plantation state in Volodya Dubinin Park and Pisarzhevsky Park is carried out. The species composition, age structure and health status of trees have been studied. The taxonomic diversity of of the Dibinin Park is rather poor and has 27 species and 2 cultivars. The Conifers are not presented. Dominating species are Acer platanoides L, Populus deltoides Marsh.and also invasive species Morus alba L., Acer negundo L., Robinia pseudoacacia L. Dendroflora of Pisarzhevsky Park is more multifarious and totals 40 species and 1 cultivar. There are many conifers. Dominating species are Pinus nigra Arnold. The number of invasive species is small. Almost half of all trees in Volodya Dubinin Park are young plants. However, such high indicator is provided by numerous self-sown plants of Morus alba, Acer negundo, Acer platanoides and Sambucus nigra L. The middle-aged, senescent and old specimens prevail in Pisarzhevsky Park. Health condition of the tree majority in both parks is right enough. It is revealed that 18% of trees in Volodya Dubinin Park and 21% in Pisarzhevsky Park are defective. Trees damaged by horse-chestnut leaf miner, Dutch elm disease and polypore are found. The order of actions for the recovery of urban parklands is determined. For improvement and recovery of both parks it is necessary to fulfill territory clearing, remove defective and dead trees, conduct sanitary and rejuvenating pruning. To replace low-value and invasive tree species it is recommended a range of new resistant ornamental types including exotic and indigenous. Keywords: urban parkland , dendroflora, monitoring, species structure, age, health, renovation

Long-term transformation of submontane spruce-beech forests in the Jizerské hory Mts.: dynamics of natural regeneration

AbstractThe paper deals with development of the natural regeneration of even-aged spruce-beech forests during their transformation to uneven-aged stands with diversified structure at the Jedlový důl area in the Protected Landscape Area Jizerské hory Mts., Czech Republic. Shelterwood management system and free felling policy based on selection principles has been applied there since 1979 with the support of admixed tree species of the natural species composition, especially silver fir (Abies alba Mill.). The research was focuses on structure and development of natural regeneration with the emphasis on ungulate damage and interaction with tree layer from 1979 to 2015. In the course of 36 years, the regeneration structure was diversified towards the close-to-nature tree species composition, spatial and age structure. The number of regeneration recruits increased in average from 941 to 41,669 ind ha-1. During this period share of European beech (Fagus sylvatica L.) significantly (p < 0.01) increased (by 53.6%), while the share of Norway spruce (Picea abies [L.] Karst.) decreased (by 51.5%), such as damage caused by ungulate (by 61.4%) with the highest loses on sycamore maple (Acer pseudoplatanus L.), rowan (Sorbus aucuparia L.) and silver fir. Moreover, the parent trees had a significant negative influence on natural regeneration at smaller spacing (within a 1 - 5 m radius from the stem). Both, regeneration potential and effective role of the tree layer during the forest transformation has been confirmed as important prerequisites for ongoing forest transformation.

Effects of projected climate change on vegetation in the Blue Mountains ecoregion, USA

We used autecological, paleoecological, and modeling information to explore the potential effects of climate change on vegetation in the Blue Mountains ecoregion, Oregon (USA). Although uncertainty exists about the exact nature of future vegetation change, we infer that the following are likely to occur by the end of the century: (1) dominance of ponderosa pine and sagebrush will increase in many locations, (2) the forest-steppe ecotone will move upward in latitude and elevation, (3) ponderosa pine will be distributed at higher elevations, (4) subalpine and alpine systems will be replaced by grass species, pine, and Douglas-fir, (5) moist forest types may increase under wetter scenarios, (6) the distribution and abundance of juniper woodlands may decrease if the frequency and extent of wildfire increase, and (7) grasslands and shrublands will increase at lower elevations. Tree growth in energy-limited landscapes (high elevations, north aspects) will increase as the climate warms and snowpack decreases, whereas tree growth in water-limited landscapes (low elevations, south aspects) will decrease. Ecological disturbances, including wildfire, insect outbreaks, and non-native species, which are expected to increase in a warmer climate, will affect species distribution, tree age, and vegetation structure, facilitating transitions to new combinations of species and vegetation patterns. In dry forests where fire has not occurred for several decades, crown fires may result in high tree mortality, and the interaction of multiple disturbances and stressors will probably exacerbate stress complexes. Increased disturbance will favor species with physiological and phenological traits that allow them to tolerate frequent disturbance.

Shift in fungal communities and associated enzyme activities along an age gradient of managed Pinus sylvestris stands.

Forestry reshapes ecosystems with respect to tree age structure, soil properties and vegetation composition. These changes are likely to be paralleled by shifts in microbial community composition with potential feedbacks on ecosystem functioning. Here, we assessed fungal communities across a chronosequence of managed Pinus sylvestris stands and investigated correlations between taxonomic composition and extracellular enzyme activities. Not surprisingly, clear-cutting had a negative effect on ectomycorrhizal fungal abundance and diversity. In contrast, clear-cutting favoured proliferation of saprotrophic fungi correlated with enzymes involved in holocellulose decomposition. During stand development, the re-establishing ectomycorrhizal fungal community shifted in composition from dominance by Atheliaceae in younger stands to Cortinarius and Russula species in older stands. Late successional ectomycorrhizal taxa correlated with enzymes involved in mobilisation of nutrients from organic matter, indicating intensified nutrient limitation. Our results suggest that maintenance of functional diversity in the ectomycorrhizal fungal community may sustain long-term forest production by retaining a capacity for symbiosis-driven recycling of organic nutrient pools.

Communities of tree vegetation and wood-destroying fungi in parks of the Kyiv city, Ukraine

Abstract Selected forestry parameters were investigated in the system of tree vegetation and wood-destroying fungi in parks of the Kyiv city along a gradient of recreational transformation. We investigated vitality, age structure and health conditions of woody plants (Acer platanoides L., Aesculus hippocastanum L., Carpinus betulus L., Frangula alnus Mill., Pinus sylvestris L., Quercus robur L., Q. rubra L., Sambucus nigra L., Tilia cordata Mill.), and species, systematic, trophic and spatial compositions of xylotrophic fungi (27 species of xylotrophs representing 22 genera, 16 families, 6 orders of divisions Basidiomycota; class Agaricomycetes). The results showed that the communities of tree vegetation and xylotrophic fungi in parks depend on the degree of recreational transformation of the environment. Vitality, age structure and health conditions of trees altered species composition of xylotrophs.

Determination of Growth Rate and Age Structure of <i>Boswellia papyrifera</i> from Tree Ring Analysis: Implications for Sustainable Harvest Scheduling

Boswellia papyrifera is a multipurpose deciduous species that grows in Combretum – Terminalia deciduous woodlands of Ethiopia. It is widely known for its commercial frankincense production. The B. papyrifera woodland is under a problematic state of population decline due to heavy encroachment and unsustainable tapping. To sustainably manage such a sensitive ecosystem needs exact knowledge of growth rates and age structure of trees where such information on tropical trees under natural condition is rather poor. In this study growth rate and age of B. papyrifera was determined from tree ring analysis. The study was carried out in Lemlem Terara, Metema district, Ethiopia. The mean annual diameter growth rate of B. papyrifera derived from the mean ring-width is 2.32mm and varies among sample trees. All sampled trees showed a comparable general growth trend which can be divided into three phases – i) good growth in the beginning, ii) phase with depression in middle and iii) increase in ring width. The average age of B. papyrifera trees growing in the study site is estimated to be about 75 years. Although there is strong correlation between diameter of a tree and age, the result from this study highlighted that age-size relations should be used cautiously as the diameter may not reflect the true age. The result from this study is important input to develop strategic plan for the species regarding tapping frequency and intensity as per the annual increment of the species. For further dendrochronological studies of the species, it is recommended to take samples from different size classes and slope gradients for better and reliable results. In future, the use of tree ring analysis as a tool to understand growth dynamics and age structure of trees species, and their response to climate variability should be strengthen in Ethiopian. Keywords: Boswellia papyrifera, Annual growth rings, Diameter growth rate, Age structure, Ethiopia.

Can airborne laser scanning assist in mapping and monitoring natural forests?

Old-growth boreal forests display high within-stand structural variation, with large variation in tree sizes and age structure, a heterogeneous horizontal spatial pattern with gaps of different sizes and multi-layered canopies. Old managed forests, on the other hand, are characterized by more homogeneous structural patterns. In many parts of Europe, no true ‘virgin forests’ remains. Still, in many places forests previously influenced by selective logging have been abandoned, and is now developing towards a more natural forest structure. Such near-natural forest areas can be of special importance for forest biodiversity and related ecosystem services, and it is therefore important to map and monitor such forests. Recently, airborne laser scanning (ALS) has been applied to provide ecologically relevant information on forest structure. The advantage of ALS is that it can characterize three-dimensional forest structure in fine detail across broad areas, replacing more labour-intensive field-based measurements.In this study, we use ALS to compare the structural characteristics of 89 near-natural and 280 managed old forest stands in a 17,000ha boreal forest study site in southeastern Norway. For the study area, both maps of logging history separating old near-natural and old managed forests, and high-resolution ALS data was available.Our aim was to investigate if ALS data could be used to separate vertical and horizontal forest structure in old near natural versus old managed forests. We also wanted to compare different methods for classification, and to describe the potential for use of ALS in classification of forest naturalness for future mapping and monitoring purposes.We found that ALS data had a strong potential in separating stands of old near-natural forests from old managed stands. The most important metrics for classification were those reflecting canopy height, canopy density, variation in canopy height, number of trees per area and gap patterns. This fits well with ecological knowledge of relevant structural differences between forests of different degree of naturalness. Both vertical and horizontal metrics provided useful input to the classification, but the horizontal metrics performed slightly better on accuracy and were easier to interpret. Although the method has a good potential for wider use in boreal forest landscapes, the need for local reference data for calibration as well as the importance of ALS pulse density for precision of classification should be further investigated.Large-scale spatial information on remaining source areas of natural and near-natural forests will be essential in order to manage forests in a way that safeguards biodiversity and ecosystem services. We suggest that classification of forest naturalness based on ALS data can be a helpful tool in future forest mapping and monitoring.

Local-scale and regional climate controls on historical fire regimes in the San Juan Mountains, Colorado

In ponderosa pine and mixed conifer ecosystems of the Southwestern US, regional-scale climate tends to synchronize fire years among study sites and increase fire extent or severity within a forest. At landscape scales (1–100km2), fire frequency and severity may also be influenced by local-scale differences in elevation and aspect, including fire barriers in rugged terrain. This study examines local-scale and regional controls of past fire regimes in three tributary watersheds of the San Juan Mountains of southwestern Colorado. In each watershed, we sampled fire-scarred trees and tree age structure and identified fire years and cohorts of post-fire tree recruitment. Fire frequency varied by aspect, and we observed the largest differences between the north- and south-facing aspects in the two largest basins. Fire severity was also different by aspect, with low-severity fire regimes on south-facing slopes and mixed-severity fire on north-facing slopes. The majority of fire years were unique, single-basin fires, indicating a lack of synchrony of fire years among basins, which we attributed to fire barriers and rugged terrain. We conducted Superposed Epoch Analysis (SEA) on two groups of fire years, to show average climate conditions before and during fire years. The first group were unique single-basin fires (n=27) and the second group included all years when synchronous fire burned in two or three basins (n=15). Both groups had significantly dry Palmer Drought Severity Index (PDSI) values during the fire year (p<0.01), while the second group also showed significantly wet conditions for two years prior to the fire year (p<0.01). Steep topography and fire barriers likely reduced the influence of regional climatic on the frequency and timing of fires for individual basins, though fires still burned during years of regional drought. Rugged terrain also contributed to asynchronous fire years among basins and longer fire return intervals compared with other ponderosa pine and mixed conifer forests in the region.

海南霸王岭陆均松空间分布格局及其与微生境异质性的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 海南霸王岭陆均松空间分布格局及其与微生境异质性的关系 DOI: 10.5846/stxb201406061165 作者: 作者单位: 海南大学农学院,中国热带农业科学院橡胶研究所,中国林业科学研究院资源信息研究所,海南霸王岭国家级自然保护区管理局,海南霸王岭国家级自然保护区管理局,海南霸王岭国家级自然保护区管理局 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31270678) The relationships between microhabitat heterogeneity and the spatial distribution of Dacrydium pectinatum in Bawangling, Hainan Island Author: Affiliation: College of Agriculture Hainan University,Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences,Research Institute of Forest Resource Information Techniques，Chinese Academy of Forestry,Hainan Bawangling National Natural Reserve,Hainan Bawangling National Natural Reserve,Hainan Bawangling National Natural Reserve Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:应用地统计学及限制性排序分析方法,对海南霸王岭陆均松(Dacrydium pectinatum)幼苗、幼树、成树及其微生境因子的空间分布特征进行分析。结果表明:1)陆均松不同生活史阶段空间分布格局存在明显差异,幼苗阶段表现为聚集性分布,具有显著的空间自相关结构,聚集强度随年龄增长呈逐渐减弱趋势;2)RDA分析表明,陆均松空间分布格局与微生境因子的关系在不同生活史阶段存在差异,生境过滤的影响会随着生活史阶段的不同而有所差别;3)微生境变量对陆均松幼苗、幼树、成树空间变异的总解释量分别为78.4%、41.2%、33.6%,微生境因素对陆均松分布的限制作用主要集中在幼苗阶段;4)在大尺度条件下,PCNM变量与微生境变量具有较大的共同解释量(22.2%),存在典型的"诱导空间变差"现象,微生境变量空间变化引起响应变量即陆均松幼苗、幼树、成树的分布产生类似的空间结构。研究结果证实了微生境因子与不同生活史阶段陆均松分布的关联性,为深入理解陆均松种群维持机制、空间分布格局、更新动态与生境的关系提供科学依据。 Abstract:Dacrydium pectinatum is the only Dacrydium genus of Podocarpaceae family in China. It is one of the symbolic species in tropical mountain rain forest in Hainan Island and one of the key species to maintain the natural communities in that region. Its distribution range is very narrow and it can only be found in the forest region of Bawang Mountain, Jianfengling Mountain and Diaoluoshan Mountain. From the beginning of 1960s, the natural forest of D. pectinatum has been severely damaged because of people's massive logging of tropical forests in Hainan. As a result the distribution area of D. pectinatum has become ever smaller, the quality of D. pectinatum forest has gotten ever worse, and it has become ever harder for the D. pectinatum to naturally regenerate themselves. What's worse, there has emerged a decline in tree-age structure. Based on this situation, D. pectinatum was listed in China Rare and Endangered Plants Red Data Book as the third degree of endangered plants in 1992. The paper first defines the three stages of D. pectinatum growth based on its diameter at breast height and tree height. Specifically seedling is defined as the tree with a height under 50 cm, sapling refers to the tree with a DBH lower than 10 cm and a height over 50 cm, and matured trees are those whose DBH are larger than 10 cm. The paper used geostatistics and constrained ordination analysis method to analyze the space distribution characteristics of D. pectinatum in three life stages from the perspective that there is relevance between its space distribution in different life stages and microhabitats factors. Also, the spatial autocorrelation of 11 microhabitats is analyzed. The results showed that: 1) there was an obvious difference in the spatial distribution of D. pectinatum in its different life stages. The seedlings were in aggregating distribution and lived with significant spatial autocorrelation. However, the aggregating intensity gradually weakened with the seedlings growing into sapling and then to matured trees; 2) RDA analysis showed that there were significant differences in the relationship between the distribution patterns and microhabitat factors in different life stages of D. pectinatum, and the effect of habitat filtering varied with the change in its life stages. 3) The effect of microhabitat variables on the spatial variability of the seedling, the sapling, and the mature trees were 78.4%, 41.2%, and 33.6%, respectively. In the whole life stage, the period from the seedling to the sapling is the key to successful plant colonization. And seedlings have got stronger environmental sensitivity than the adult tree. It follows that the restrictive effect of microhabitat factors on D. pectinatum's distribution mainly occurred in its seedling stage; 4) In sound conditions, 22.2% variation can be interpreted by PCNM variables and microhabitat variables in common. And a typical 'induced spatial variation' phenomenon was found, which means that the spatial variation of microhabitat variables can result in the spatial variation of D. pectinatum throughout its seedling, sapling stage and matured stage. The results confirmed the relevance between microhabitats and the distribution of D. pectinatum in different life stages. And the paper provided a scientific foundation for better understanding of the relationship between the mechanisms of population maintenance, the spatial distribution pattern of D. pectinatum, and its regeneration dynamics. If there will be any further research on this topic, it is suggested that the monitoring and the study be carried out during a longer time span, and larger size of sample be studied, for a more accurate analysis of the influence of microhabitat factors on seedling regeneration and its survival pattern. 参考文献 相似文献 引证文献

Structural and Spatial Characteristics of Old-Growth Temperate Deciduous Forests at Their Northern Distribution Limit

Relic old-growth forests are unique witnesses of long-term forest dynamics that can be used as reference conditions for ecosystem-based forest management. In temperate deciduous forests, catastrophic stand-replacing disturbances are rare, and stand dynamics are controlled by endogenous tree-by-tree replacement. Processes might be different at the northern distribution limit of temperate deciduous forests, because of differences in climate and disturbance regimes. We studied tree species composition, diameter, age, and spatial structures of 11 old-growth temperate deciduous stands across an age gradient. Stand characteristics differed from expectation, based on previous studies that were conducted in the central region of the range of temperate deciduous forests. Instead of increasing with age, tree species richness was higher in stands <120 years old because of the presence of relatively short-lived species such as Abies balsamea and Acer rubrum. All diameter distributions followed a two- or three-parameter Weibull model, instead of a rotated sigmoid. Some age structures showed recruitment pulses, contrary to the expectation of constant recruitment, and the spatial distribution of living trees was mostly random with regard to age and species at assessed distances (<14 m). In the context of ecosystem-based forest management, our results suggest that harvest levels should vary across harvesting blocks and selection silviculture should occasionally include larger, multiple-tree gaps in addition to single-tree gaps.

Age structure of aspen forests on the Uncompahgre Plateau, Colorado

Aspen forests are one of the most dynamic forest types in western North America, responding to chronic factors of competition for resources, as well as episodes of intense herbivory, drought, and fires. The interactions of these driving factors lead to varying age structures of aspen across landscapes and through time. We characterized the age structure of aspen trees on the Uncompahgre Plateau in western Colorado, USA, to inform collaborative efforts of landscape-scale forest restoration. Over 1000 cores from 51 locations showed few aspen older than 140 years (&lt;0.5% for aspen numbers, &lt;2.5% of aspen basal area). Heavy recruitment in the late 1800s (following the last major fires) led to cohorts from 100 to 140 years of age that account for 15% of current aspen numbers and 40% of current aspen basal area. Perhaps the most important character of the current age structure is a relatively low number of aspen younger than 50 years; normal rates of tree survivorship in coming decades will lead to a substantial decline in aspen on the Plateau as these cohorts progress into older age classes. Patterns of aspen ages on the Uncompahgre Plateau differ substantially from those on the Kaibab Plateau and in Rocky Mountain National Park, owing the varying importance in space and time of driving factors. Landscape-scale increases in aspen regeneration (from major events such as fire) would be necessary to moderate the long-term decline in aspen on the Uncompahgre Plateau.

Advancing towards novel tree lines? A multispecies approach to recent tree line dynamics in subarctic alpine Labrador, northern Canada

AbstractAimComparisons of how different species respond to changing climatic conditions offer insight into future community composition and the potential formation of novel communities. This study investigated changes at a subarctic forest–tundra ecotone, or ‘tree line’. Our objectives were: (1) to explore species‐specific growth forms; (2) to identify temporal patterns of establishment and stand density; and (3) to explore relationships between climate and recruitment/survival amongst co‐dominant tree species, with the expectation that climate change will affect species differentially.LocationThe Mealy Mountains in the High Subarctic Tundra ecoregion in central Labrador, Canada.MethodsWe examined tree line dynamics for four tree species over the past two centuries. Using ecological and age‐structure data, we compared diameter/height relationships across the tree line and generated static age structures from which changes in stand density through time were compared. In addition, model residuals were used to quantify relationships between multi‐decadal windows of temperature/palaeotemperature/Palmer Drought Severity Index and decadal tree recruitment.ResultsTrees were more stunted as elevation increased, except for white spruce (Picea glauca) for which tree islands became the dominant growth form. The only tree seedlings found at the tree line were of larch (Larix laricina) and to a lesser extent black spruce (Picea mariana). From the age structure of trees (height &gt; 2.0 m), only black spruce showed evidence of an advancing tree line. Larch and balsam fir (Abies balsamea) have become established at the tree line most recently and have undergone greater increases in density over the past few decades. Variability in recruitment increased with elevation: larch recruitment was positively correlated with temperature and negatively correlated with drought at low elevations but negatively correlated with temperature and positively correlated with drought at high elevations, whereas black spruce recruitment was consistently positively correlated with temperature and drought.Main conclusionsThe multispecies approach provides evidence that species are responding differentially to climate. With continued climate change, we expect density increases and advances of larch and black spruce, giving rise to novel tree line communities.

Tree-Line Structure and Dynamics at the Northern Limit of the Larch Forest: Anabar Plateau, Siberia, Russia

The goal of the study was to provide an analysis of climate impact before, during, and after the Little Ice Age (LIA) on the larch (Larix gmelinii) tree line at the northern extreme of Siberian forests. Recent decadal climate change impacts on the tree line, regeneration abundance, and age structure were analyzed.The location of the study area was within the forest-tundra ecotone (elevation range 170–450 m) in the Anabar Plateau, northern Siberia. Field studies were conducted along elevational transects. Tree natality/mortality and radial increment were determined based on dendrochronology analyses. Tree morphology, number of living and subfossil trees, regeneration abundance, and age structure were studied. Locations of pre-LIA, LIA, and post-LIA tree lines and refugia boundaries were established. Long-term climate variables and drought index were included in the analysis.It was found that tree mortality from the 16th century through the beginning of the 19th century caused a downward tree line recession. Sparse larch stands experienced deforestation, transforming into tundra with isolated relict trees. The maximum tree mortality and radial growth decrease were observed to have occurred at the beginning of 18th century. Now larch, at its northern boundary in Siberia, is migrating into tundra areas. Upward tree migration was induced by warming in the middle of the 19th century. Refugia played an important role in repopulation of the forest-tundra ecotone by providing a seed source and shelter for recruitment of larch regeneration. Currently this ecotone is being repopulated mainly by tree cohorts that were established after the 1930s. The last two decades of warming did not result in an acceleration of regeneration recruitment because of increased drought conditions. The regeneration line reached (but did not exceed) the pre-LIA tree line location, although contemporary tree heights and stand densities are comparatively lower than in the pre-LIA period. The mean rate of tree line upward migration has been about 0.35 m yr-1 (with a range of 0.21–0.58), which translates to a tree line response to temperature of about 55 m °C-1.

Лісовий фонд басейну р. Вижівка: сучасний стан та особливості використання

Current state of forest fund of Vyzhivka River basin was described and evaluated. Statistics and dynamics of forest reserves and composition of tree species and age structure of forests were analyzed. Groups of forests by economic importance and the main types of environmental management within forest fund of studied area were allocated. Both negative and positive sides of it were shown. Key words: forest fund, forest species composition, age structure of forests, logging, reforestation.

Land-use legacies: multi-centuries years-old management control of between-stands variability at the landscape scale in Mediterranean mountain forests, France

Traditional land use has shaped the Mediterranean region for a long time and has resulted in present-day complex landscapes. The land abandonment dating from the 19&lt;sup&gt;th&lt;/sup&gt; century at a site located in the southwestern Alps (France) makes it possible to analyse how present-day forest stands inherit from past land uses. Tree composition and tree age structure were analysed in three stands resulting from different former land uses, i.e. ancient coppice, formerly grazed area and formerly tilled area. The ancient coppice contains the densest tree cover and is dominated by Fagus sylvatica, whereas the formerly ploughed and&amp;nbsp; grazed areas are less dense, both dominated by Pinus sylvestris. Forest stand in the ancient coppice is older than in the formerly grazed area, and forest stand is the youngest in the formerly ploughed area. These stand differences are largely explained by former land use and the abandonment process. Albeit strong changes result from the land abandonment, these landscapes inherit aspects of their land use during the 19&lt;sup&gt;th&lt;/sup&gt;century at least and the dynamics does not match the expected pattern of soil fertility. &amp;nbsp;

American chestnut (Castanea dentata) to northern red oak (Quercus rubra): forest dynamics of an old-growth forest in the Blue Ridge Mountains, USA

We analyzed tree species composition and age structure in a rare, old-growth Quercus rubra L. (northern red oak) forest at Bluff Mountain Preserve, North Carolina, to assess potential changes associated with Cryphonectria parasitica (Murrill) M.E. Barr (chestnut blight), selective logging, livestock grazing, ice storms, wind events, and fire history. We established forest inventory plots to determine the forest composition, vertical structure, and age of the high-elevation Q. rubra dominated forest. We developed the longest Q. rubra dendroecological history (1671–2009) in North America. Several living Q. rubra individuals were more than 250 years old. The frequency, magnitude, and spatial extent of canopy disturbance events were shown in radial growth trends in Q. rubra samples. We also examined Q. rubra climate – radial growth relationships to compare high-elevation Q. rubra climate response patterns with results from lower elevation Quercus dendroclimatological studies. Stand-wide release events corresponded with the loss of Castanea dentata (Marsh.) Borkh. (American chestnut) during the 1930s and frequent ice storms or wind events. Although we observed fire scars on living hardwood trees, we did not find fire scars on the remnant logs. The lack of fire scars on the remnant logs indicates that the observed fires likely occurred during the second half of the 20th century. Quercus rubra were most climatically sensitive to cool March temperatures. Quercus rubra sampled at higher elevations were more sensitive to temperature than lower elevation Quercus spp. trees, which may indicate higher sensitivity to March frosts. Quercus rubra has been a dominant species at Bluff Mountain for the past 300 years; however, our data indicate that the forest will transition to support a much stronger Acer saccharum Marsh. (sugar maple) component during the next 50 years. This study provides a multicentury perspective to guide conservation efforts and forest management in high-elevation Quercus spp. forests in the southern Appalachian Mountains.

Response of ground vegetation and epiphyte diversity to natural age dynamics in a Central European mountain spruce forest

AbstractQuestionNatural forest age dynamics is often more or less cyclic, with profound temporal changes in stem density and tree size, tree age structure, deadwood frequency and the abundance of canopy gaps. We investigated the response of ground and epiphyte vegetation to the natural forest age dynamics of an old‐growth spruce forest focussing on (1) the influence of stand age‐related shifts in forest structure and related changes in soil conditions on the diversity and composition of plant communities, (2) differences in the species turnover of cryptogamic epiphytes and ground vegetation in relation to forest age development, and (3) the importance of later (advanced) forest development stages for characteristic epiphyte communities.LocationHigh‐montane old‐growth spruce forest (Picea abies(L.)Karst.) on Mt. Brocken, Harz Mountains, Germany.MethodsFive defined forest development stages (regeneration to decay) were investigated with five 100‐m² plots for each stage, in which we studied forest structure, ground vegetation and the epiphytes of living trees and dead trunks.ResultsThe ground vegetation did not significantly change across the forest development stages. Epiphyte diversity on dead standing trees markedly increased towards later stages, with the highest diversity in the over‐mature and decay stages. Diversity of epiphytes on lying trunks was highest in early development stages. Trees in decay as well as regeneration stage included a set of characteristic epiphytes, being rare or absent in the other stages.ConclusionsDeadwood, i.e. trees and lying trunks and their epiphytes, outlast the oldest individuals of the tree layer and are still present in the early stages of the following forest generation. Epiphyte diversity on lying deadwood was higher in young than late forest development stages. Habitat continuity presents a fundamental difference to managed forests; it promotes species with dispersal limitations, which are common among cryptogamic epiphytes.