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Managing forests to sustain their diversity and functioning is a major challenge in a changing world. Despite the key role of understory vegetation in driving forest biodiversity, regeneration and functioning, few studies address the functional dimensions of understory vegetation response to silvicultural management.We assessed the influence of the silvicultural regimes on the functional diversity and redundancy of European forest understory. We gathered vascular plant abundance data from more than 2000 plots in European forests, each associated with one out of the five most widespread silvicultural regimes. We used generalized linear mixed models to assess the effect of different silvicultural regimes on understory functional diversity (Rao's quadratic entropy) and functional redundancy, while accounting for climate and soil conditions, and explored the reciprocal relationship between three diversity components (functional diversity, redundancy and dominance) across silvicultural regimes through a ternary diversity diagram.Intensive silvicultural regimes are associated with a decrease in functional diversity and an increase in functional redundancy, compared with unmanaged conditions. This means that although intensive management may buffer communities' functions against species or functional losses, it also limits the range of understory response to environmental changes.Policy implications. Different silvicultural regimes influence different facets of understory functional features. While unmanaged forests can be used as a reference to design silvicultural practices in compliance with biodiversity conservation targets, different silvicultural options should be balanced at landscape scale to sustain the multiple forest functions that human societies are increasingly demanding. [ABSTRACT FROM AUTHOR]

Knowledge of the quantity of woody biomass of poplar short-rotation coppice (SRC) on agricultural land is a basic tool for management decisions like rotation length, volume production and the financial balance sheet of economic activities. The expansion of SRC requires a fast, reliable, easily applicable and cheap method for estimating the biomass yield, but existing methods are based on labour-demanding and lengthy measurements of all shoots per tree. The objective of this study was to verify a novel rapid biomass estimation method that uses averaged attributes of only a few largest shoots as a predictor variable for woody biomass in a poplar SRC, hybrid clone J-105 (Populus nigra × P. maximowiczii). Using data from 39 sample stumps with 187 shoots in total, we modelled shoot biomass as a function of an increasing number of shoots in interaction with different shoot parameters at two poplar SRC plantations. Results showed that the DBH of only three of the largest shoots per stump proved to be accurate estimators of the total shoot biomass of the individual stump. Comparison of biomass estimates at the stand level with a real amount of biomass indicated differences between 6-14%, depending on the site. [ABSTRACT FROM AUTHOR]

Between 2010 and 2011 a field survey dedicated to Dracaena cinnabari (DC) population was conducted in Firmihin, Socotra Island (Yemen). It’s main goal was to collect data that would make it possible to unbiasedly estimate main characteristics of the local DC population. Our motivation was to provide reliable information to support decision-making processes as well as other research activities. At the same time we were not aware of a survey which could provide this kind of statistical-sound estimates for the whole population covering an area of almost 700 ha.

Aim: Natural disturbances influence forest structure, successional dynamics and consequently, the distribution of species through time and space. We quantified the long‐term impacts of natural disturbances on lichen species richness and composition in primary mountain forests, with a particular focus on the occurrence of endangered species. Location: Ten primary mountain spruce forest stands across five mountain chains of the Western Carpathians, a European hotspot of biodiversity. Methods: Living trees, snags and downed logs were surveyed for epiphytic and epixylic lichens in 57 plots. Using reconstructed disturbance history, we tested how lichen species richness and composition was affected by the current forest structure and disturbance regimes in the past 250 years. We also examined differences in community composition among discrete microhabitats. Results: Dead standing trees as biological legacies of natural disturbances promoted lichen species richness and the occurrence of threatened species at the plot scale, suggesting improved growing conditions for rare and common lichens during the early stages of recovery post disturbance. However, high‐severity disturbances compromised plot‐scale species richness. Both species richness and the number of old‐growth specialists increased with time since disturbance (i.e., long‐term uninterrupted succession). No lichen species was strictly dependent on live trees as a habitat, but numerous species showed specificity to logs, standing objects or an admixture of tree species. Conclusions: Lichen species richness was lower in regenerating, young and uniform plots compared with overmature and recently disturbed areas. Natural forest dynamics and its legacies are critical to the diversity and species composition of lichens. Spatio‐temporal consequences of natural dynamics require a sufficient area of protected forests for provisioning continual habitat variability at the landscape scale. Ongoing climatic changes may further accentuate this necessity. Hence, we highlighted the need to protect the last remaining primary forests to ensure the survival of regionally unique species pools of lichens. [ABSTRACT FROM AUTHOR]

• Pre-disturbance tree size increases but sprout competition decreases growth of resprouting trees. • Pre-disturbance tree size and competition affect resprouting success. • Resprouting vigour positively affects long-term sprout growth and survival. • Dominant trees restore their dominance after disturbances due to faster sprout growth. • Early sprout thinning could enhances productivity in coppices. Forest trees of many species are able to recover from logging and other severe disturbances by resprouting. Due to rapid growth, sprouts often form a significant part of forest regeneration and are also a key component of coppice forests. However, there is a large variation in both resprouting success and sprout growth whose drivers are still poorly understood in forest trees. Here, we test the hypothesis that pre-disturbance tree size and competition not only influence resprouting success and initial sprout growth (i.e., resprouting vigour) but also, together with sprout competition and resprouting vigour, drive long-term growth and survival of resprouting trees. To test it, we analysed data on 2236 trees of four common temperate European broadleaved species collected in a fenced 4 ha-experimental plot before and for seven years after harvesting. The plot was divided into 16 subplots with different densities of residual trees left, ranging from 0 to 200 tree per ha. The great majority of the logged trees recovered and were alive at the end of the study. Both pre-harvest tree size and competition affected resprouting success, but the direction of these effects varied with species. In all species, sprout growth increased with pre-harvest tree size and with resprouting vigour but declined with post-harvest competition from nearby resprouting and uncut trees. The overall faster sprout growth in originally larger trees suggests that dominant canopy trees are likely to restore their dominance in the new canopy after disturbances, thus ensuring long-term persistence and seed production. The decline in sprout growth due to intense competition among resprouting trees indicates that early thinning could enhance sprout performance and it could also be used to suppress undesired species. [ABSTRACT FROM AUTHOR]

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In open woodlands and savannas, fire is often the dominant disturbance that shapes and maintains their structure and dynamics. Numerous studies have explored tree-grass coexistence under different fire regimes in these ecosystems; however, there is a lack of research on the tree-tree relationship in the presence or absence of fire. In the present study, we explored the effects of fire regime on tree spatial pattern, mortality and regeneration in the Argentine Caldenal, which is one of the most endangered and least studied open woodlands in the Neotropics. While there was no significant difference in the overall tree density between frequently burned and fire-excluded regimes, we found clear divergences between fire regimes in the within-stand spacing of not only all trees, but also of large and small trees in addition to their spatial interactions. In contrast with previous results from other frequently burned open forests, trees in the Caldenal were randomly distributed in burned plots whereas both mid- and long-term fire exclusion lead to the strong short-scale aggregation of trees. In the absence of fire, both large and small trees were significantly clumped, but in the frequently burned woodlands, large and small trees had a tendency to repulsion and aggregation, respectively. Fire regime also significantly affected tree mortality and regeneration mechanisms in the Caldenal. Our mortality analysis indicated that fire suppression led to the shift from fire-induced to competition-driven mortality of trees. When analysing tree regeneration, we found a lack of seedlings in any of the fire regimes but the presence of vigorous sprouting only in frequently burned plots. The present study thus revealed the key role of frequent fires in the Caldenal open woodlands because recurrent burning not only shaped the spatial arrangement of trees, but fire-induced mortality also triggered an essential tree recruitment mechanism in these ecosystems. [ABSTRACT FROM AUTHOR]

Shrub encroachment is a frequently observed phenomenon in the arid and semi-arid biomes. In the dry forests of the Argentine Chaco ecoregion that are affected by shrub encroachment, the growing demand for grazing areas has led to the creation of a silvopastoral system. Under the Chaco silvopastoral system, a commonly used treatment to disrupt the excessive shrub layer and promote the growth of grasses is roller-chopping by a tractor-pulled iron drum. While previous studies evaluating the effects of roller-chopping on diversity have focused mostly on the herbaceous stratum as the primary source of forage, much less is known about the effects of roller-chopping on woody plants. To fill this gap, we measured woody plants of the shrub layer in a low-intensity roller-chopping experiment in northern Argentina after applying different frequencies of roller-chopping in a semi-arid Chaco forest area with a well-developed shrub layer. Data were collected in an experiment in which 3 different roller-chopping treatments were applied: a single two-pass roller-chopping in the summer of 2006/2007 (RCh1); a one-pass roller-chopping in the summer of 2006/2007, repeated in the summer of 2014/2015 (RCh2); and no treatment (Control). In each treatment, 16 circular, randomly placed plots with a radius of 9 m were sampled, and all woody plants in the shrub layer with a diameter ≥10 mm at the base were recorded. The diversity was analysed using profiles of alpha and beta diversity and by calculating the average distance from an individual circular plot to the treatment group centroid defined in the principal coordinate space. In total, 26 species of woody plants were recorded, of which 24 were found in Control, 22 in RCh1, and 23 in RCh2. Although the alpha diversity differed only slightly among the treatments, the beta diversity of the roller-chopped treatment areas was generally higher than that of the untreated plots. The species composition of the roller-chopped plots differed little from that of the control plots. Our study revealed little overall effect of roller-chopping on the species diversity and composition of woody plants. The transformation of the Chaco forest degraded by shrub encroachment to a silvopastoral system by roller-chopping is changing the structure of the forest but to a large extent has retained the presence and the relative abundance of woody plant species. We conclude that roller-chopping is a good management tool to reduce woody plant encroachment and create a silvopastoral system while preserving ecosystem functions. [ABSTRACT FROM AUTHOR]

Sprouting is a common life history strategy in tree communities and is crucial for coppice management of woodlands. Recently, there has been increasing interest in coppice restoration throughout Europe and several studies have explored the sprouting ability of tree stumps in the restored stands. Though the spatial distribution of trees has been previously found to affect ecological processes in many ecosystems, no study has so far considered the importance of spatial interactions during the process of coppice restoration. The present study attempts to fill this gap by analyzing fine-scale spatial patterns in sprouting and mortality in a newly restored oak coppice with different densities of residual timber trees. Univariate and bivariate point pattern analyses were used to quantify the observed spatial patterns. While no significant spatial associations were found between residual trees and dead (post-harvest non-sprouting) stumps, our mortality analysis revealed clear non-random interactions between stumps themselves. Negative distance- and density-dependent effects in post-harvest stump mortality were observed at short scales; stumps with more neighboring stumps at a close distance were significantly more likely to die after harvest. Our study demonstrated that non-random effects in mortality are not limited only to generative reproduction of trees but play also an important role in vegetative regeneration of one of the main European broadleaved tree species. [ABSTRACT FROM AUTHOR]

Host size and distance from an infected plant have been previously found to affect mistletoe occurrence in woody vegetation but the effect of host plant competition on mistletoe infection has not been empirically tested. For an individual tree, increasing competition from neighbouring trees decreases its resource availability, and resource availability is also known to affect the establishment of mistletoes on host trees. Therefore, competition is likely to affect mistletoe infection but evidence for such a mechanism is lacking. Based on this, we hypothesised that the probability of occurrence as well as the abundance of mistletoes on a tree would increase not only with increasing host size and decreasing distance from an infected tree but also with decreasing competition by neighbouring trees. Our hypothesis was tested using generalized linear models (GLMs) with data on Loranthus europaeus Jacq., one of the two most common mistletoes in Europe, on 1015 potential host stems collected in a large fully mapped plot in the Czech Republic. Because many trees were multi-stemmed, we ran the analyses for both individual stems and whole trees. We found that the probability of mistletoe occurrence on individual stems was affected mostly by stem size, whereas competition had the most important effects on the probability of mistletoe occurrence on whole trees as well as on mistletoe abundance. Therefore, we confirmed our hypothesis that competition among trees has a negative effect on mistletoe occurrence. [ABSTRACT FROM AUTHOR]

Resprouting multi-stemmed woody plants form an important component of the woody vegetation in many ecosystems, but a clear methodology for reliable measurement of their size and quick, non-destructive estimation of their woody biomass and carbon stock is lacking. Our goal was to find a minimum number of sprouts, i.e., the most easily obtainable, and sprout parameters that should be measured for accurate sprout biomass and carbon stock estimates. Using data for 5 common temperate woody species, we modelled carbon stock and sprout biomass as a function of an increasing number of sprouts in an interaction with different sprout parameters. The mean basal diameter of only two to five of the thickest sprouts and the basal diameter and DBH of the thickest sprouts per stump proved to be accurate estimators for the total sprout biomass of the individual resprouters and the populations of resprouters, respectively. Carbon stock estimates were strongly correlated with biomass estimates, but relative carbon content varied among species. Our study demonstrated that the size of the resprouters can be easily measured, and their biomass and carbon stock estimated; therefore, resprouters can be simply incorporated into studies of woody vegetation. [ABSTRACT FROM AUTHOR]

• Coppicing improved photosynthesis under drought. • Coppicing also improved photosynthesis when the soil was wet. • Most water stressed were seedlings followed by mature trees. • Water use efficiency (WUE) was highest in mature trees, lowest in seedlings, while coppicing was average. • Coppicing is a viable stand management option for drought prone sites. Droughts negatively affect tree vitality, growth and mortality in temperate forests. Appropriate forest management may help mitigate these adverse effects. One such silvicultural system is coppicing, which increases a stand's drought resistance compared to high forests, but the underlying mechanisms are not well explored. Here, we aimed to deepen our mechanistic understanding of the performance of sessile oak (Quercus petraea) in response to drought stress. We compared mature trees, young coppice and seedlings. We measured seasonal variation of tree water status, photosynthesis, and biometric traits of sessile oak over three growing seasons. Coppicing increased water use and photosynthesis both under drought stress conditions and favorable conditions. During mild to severe drought, coppiced trees had better access to water and assimilated more carbon per unit of leaf area than seedlings and mature trees. The lowest predawn water potential of -4.21 MPa was recorded in seedlings, which was by 0.8 MPa less than in the coppice. Photosynthesis rates were highest in the coppice, but the water use efficiency of the coppice fell in between mature trees (higher WUE i) and seedlings (lower WUE i). Combined measurements of chlorophyll fluorescence and gas exchange suggested that coppice, seedlings and mature trees responded differently to drought. Coppice had the highest yield in light reactions of photosynthesis and the highest carbon assimilation. Coppicing improves the physiological vitality of young sprousts which makes it a suitable silvicultural system for dry sites. [ABSTRACT FROM AUTHOR]

• Sprout biomass in coppices declined with increasing density of standards. • The effect of standards differed significantly among studied species. • Sprout biomass on stand level increased even in the highest densities of sprouting stumps. • Tilia cordata is the most productive species in Central European coppices. • Interspecific differences in sprout growth after tree harvesting resulted in significant shift in tree species composition. Traditional coppices and coppice-with-standards were widely used throughout Europe and Asia for centuries but were largely abandoned in the second half of the 19th century, especially in central and northwestern Europe. In last decades, there has been a renewed interest in traditional coppicing for nature conservation and most often, for rapid woody biomass production. However, there is little information on biomass productivity of traditional coppices and what affects it. Here, we focused on the effects of stand density, standards and tree species composition on sprout biomass production in newly restored coppices in the Czech Republic. We measured sprouts and calculated sprout biomass 7 years after the harvest from 2013 resprouting stumps in two 4 ha experimental plots. Each plot was divided into 64 subplots with different densities of standards and sprouting stumps. Total sprout biomass declined with increasing density of standards, but the effect of standards differed significantly among studied species. Whereas increasing density of standards decreased sprout biomass in Quercus petraea and Carpinus betulus, it did not affect sprout biomass productivity in Acer campestre and Tilia cordata. Sprout biomass on stand level increased linearly with increasing number of sprouting stumps and we observed no levelling of this relationship even in the highest densities of stumps. We also found significant shift in tree species composition with steeply declining relative abundance of Qurcus in favor of other studied tree species. [ABSTRACT FROM AUTHOR]

• Current DBH distribution shapes are driven by historical disturbance regimes. • Low-severity disturbances showed a reverse J-shaped diameter distribution. • High-severity disturbance lead to a unimodal diameter distribution. • Time and severity of last disturbance are good predictors of DBH distribution shape. Natural disturbances strongly influence forest structural dynamics, and subsequently stand structural heterogeneity, biomass, and forest functioning. The impact of disturbance legacies on current forest structure can greatly influence how we interpret drivers of forest dynamics. However, without clear insight into forest history, many studies default to coarse assumptions about forest structure, for example, whether forests are even or unevenly aged. The aim of this study was to analyze the effects of past disturbances on the current diameter distributions of Norway spruce (Picea abies (L.) Karst.)-dominated landscapes throughout the Carpathian Mountains. Our dendroecological dataset comprises tree cores from 339 plots (7,845 total tree cores), nested within 28 primary forest stands, known to vary greatly in the severity of historical disturbances. Our analyses revealed that historical disturbances had a strong and significant effect on the current diameter distribution shapes at the plot level. We demonstrated that mixed-severity disturbance regimes were more frequent and create a complex pattern of diameter distributions at the plot and stand scale. Here, we show that high severity disturbance was associated with unimodal diameter distributions, while low and moderate severity was associated with the reverse J-shaped distribution. This is a result of complex disturbance patterns, with structural biological legacies. Our results will have important management implication in the context of tree size heterogeneity, biomass storage, and productivity as influenced by natural disturbances. Lastly, these results demonstrate that structural changes may arise as consequences of changing disturbance regime associated with global change. [ABSTRACT FROM AUTHOR]

An observed acceleration of tree mortality rates in European forests has been attributed to the impacts of climate change and extreme disturbances. Ecosystem recovery depends on regeneration success, but the recruitment of juveniles has been recognized as bottleneck in the development of forests. We investigated the potential importance of biotic (canopy tree abundance, ungulate herbivory) and abiotic (light, soil nutrients) factors in the limitation of regeneration in montane primary forests in central Europe. We used widely distributed forest inventory data (n = 348 plots) for two forest types, multiple tree taxa, and two life stages (seedlings and saplings). Seedling densities were promoted by more abundant parent trees, but saplings were either negatively influenced or unaffected by the number of conspecific adults. Browsing intensity (per capita defoliation severity) strongly limited the density of seedlings, but not saplings, at a community level. Low understory light levels were positively associated with seedling densities, but either did not affect or depressed sapling abundance A tolerance of shading was enhanced by nitrogen availability in some taxa. Our findings reflect highly complex, context‐specific regeneration processes that vary by species and life stage within species. [ABSTRACT FROM AUTHOR]

• Regional-scale dendroecological study of primary mixed beech-fir forests. • Low-and intermediate-severity disturbances were the prevailing type of events. • Plot-level events of high and very-high disturbance severities were also detected. • Overall, the forest was driven by a mixed-severity disturbance regime. Natural disturbances are key factors in the formation of forest ecosystem structure. Evaluation of the spatial and temporal extent of disturbance regimes is critical for understanding forest dynamics, forest structural heterogeneity, and biodiversity habitats. Quantifying disturbance regimes is therefore imperative for appropriate management of forests and protected areas. However, natural disturbance regimes have rarely been assessed using dendrochronological methods on a regional scale across primary mixed beech-fir forest stands - one of the dominant forest vegetation types in Europe. To study the natural disturbance regimes of beech-dominated mixed-forest stands, we established 42 permanent study plots with an area of 0.1 ha across three primary forest stands in the Western Carpathians, a region that still contains large areas of primary forest. We reconstructed each stand-level disturbance history using a tree-ring based approach. The temporal synchronicity of disturbance events was then evaluated by delineating stand-level disturbance events using a kernel density function, and through the detection of plot-level disturbances with severities greater than 10 percent. The results obtained from the chronologies showed substantial variability in time and space, especially in the mid-19th century. Low- and moderate-severity plot-level disturbance events were most common, but high- and extremely high-severity plot-level disturbance events also occurred. The observed spatial and temporal variability suggests that the beech-dominated forests were primarily driven by mixed-severity disturbance regimes, with windstorms as the main disturbance agent. This reconstruction of the disturbance regime provided unique insight into the scale of mortality processes in these beech-dominated mixed forests. This information can help guide ecological forestry in areas where both wood production and biodiversity preservation are simultaneous goals, such as by employing more spatiotemporally-complex silvicultural systems that resemble natural disturbance patterns and facilitate heterogeneous forest structures. [ABSTRACT FROM AUTHOR]

Dracaena cinnabari , the dominant endemic tree of Socotra Island (Yemen), is in serious decline. The effect this will have on the island's plant diversity remains unknown. We aimed to identify plants associated with Dracaena understorey and assess the importance of Dracaena for maintaining plant diversity. A total of 272 relevés were sampled in Dracaena understorey and in open sites to record the number of individuals of vascular plants. Species richness and composition were compared between understorey and open sites, and species associated with each of these habitats were identified. Additionally, the effect of canopy closure on species richness and abundance was analysed. We also recorded woody species composition of Dracaena stands and investigated spatial relations between Dracaena and other mature woody plants. Understorey plant species composition differed from open site composition. The former habitat showed higher β-diversity and species richness. Among recorded plants, 15 species were classified as understorey specialists, 6 as open-site specialists, and 23 as generalists. Rare species, especially endemics, were more common in the understorey. Canopy closure had differential effect on species abundances among the species classes. Species richness and total abundance were found to be highest in the understorey, particularly in the case of low-to-intermediate canopy closure where understorey and open-site specialists may co-occur. For mature woody plant species, Dracaena was spatially independent from other woody species at most distances. Our results suggest that the decline of Dracaena may negatively affect plant diversity, reduce abundance of rare endemic plants and lead to homogenization of vegetation. As no other tree species exists in the study area which could replace the Dracaena , our findings underline the importance of conservation efforts to preserve Dracaena stands on Socotra. [ABSTRACT FROM AUTHOR]