The age and size of trees are key characteristics in forest ecosystems, and large old trees have significant roles in them. Tree age and size of trees are often decoupled in naturally developed forests, but their relationship is still known only vaguely, for example regarding the strength of their correlation or the co-occurrence of large size and old age. Given their significance, understanding the occurrence of large and old trees is relevant to conservation value assessments in forests. To study the tree age-size relationship in old-growth forests, we collected data from 25 small plots (0.1 ha) in two forest landscapes in northern boreal Europe. The plots were dominated by spruce (Picea abies), with birch (Betula pubescens) as a secondary tree species. The sites had not been impacted by major disturbances for at least several centuries. We inventoried all trees in the plots with diameter ≥ 10 cm (n = 1,156) and successfully obtained age estimates from tree ring samples for 991 trees. Diameter explained 31
The growth of Pinus massoniana.Lamb in southern acidic soils is constrained by nitrogen scarcity. This study employed a four-chamber compartment system and ¹⁵N isotope tracing technology, combined with mixed ECM inoculation and varying nitrogen concentration gradients, to investigate nitrogen transfer from ECM fungi to seedlings. The results were used to evaluate transfer efficiency between donor and recipient P. massoniana plants as well as root plasticity, and a hypothetical stratified fertilization strategy was proposed. This study developed a four-chamber compartmented system to physically isolate root contact while preserving mycelial network connectivity. Acontrolled experiment was conducted using P. massoniana seedlings inoculated with mixed mycorrhizal strains, Sm, comprised Pisolithus orientalis (Po), Scleroderma citrinum (Sc), and Suillus luteus (Sl), isolated and purified from P. massoniana rhizosphere soil samples. versus non-inoculated controls (CK). Different nitrogen treatments were carried out through (¹⁵NH₄)₂SO₄ solution isotope labeling 0, 2, 4 and 6 g/L, we quantitatively assessed hyphal-mediated nitrogen translocation through CMNs across a 30 μm nylon mesh barrier. Mixed ECM inoculation significantly promoted seedling growth.Under medium nitrogen supply conditions of 4 g/L, ECM symbiosis enhanced root plasticity, total root length increased by 137
Chinese fir (Cunninghamia lancelolata) monoculture plantations, widespread in subtropical China, experience long-term productivity declines due to soil nutrient depletion and ecosystem degradation. Close-to-nature management (CTNM), characterized by the establishment of stands with mixed species composition, represents a viable strategy for improving forest health. However, the specific contributions of broadleaf species with varying growth habits to litterfall dynamics, particularly the mechanisms underlying their facilitative role in nutrient cycling, are not yet fully understood. We herein measured litter production, nutrient return, and soil properties in Chinese fir plantations after 11 years of CTNM to quantify how the introduction of broadleaf species with different growth strategies affects litterfall and nutrient return in Chinese fir plantations. Monthly litter collections were conducted over a two-year period (2022–2024) in three stand types: (1) a pure Chinese fir plantation (CLP) and the mixed plantation with (2) Phoebe bournei (MPC), and (3) Machilus pauhoi (MMC). CTNM significantly enhanced soil organic carbon (SOC), available phosphorus (AP), available potassium (AK), available nitrogen (AN), and soil C: P ratio, which in turn improved litter nutrient concentration. In all three plantations, annual total nutrient return to soil was in the order of MMC (3115.20 kg ha−1 yr−1) > MPC (2747.71 kg ha−1 yr−1) > CLP (1740.55 kg ha−1yr−1), with nutrient returns following the order: C > Ca > N > K > P > Mg > Mn. The interplanting of the fast-growing M. pauhoi in thinned gaps (MMC) resulted in significant improvements in N: P ratio, litter Mn concentration, and total nutrient return relative to CLP. These results indicate that interplanting with M. pauhoi is more effective than with P. bournei at alleviating the N and P limitations in Chinese fir plantations, thereby accelerating nutrient turnover and enhancing overall soil fertility.
Forest type is a crucial factor shaping forest ecosystem structure and carbon cycling. China has experienced substantial changes in forest composition during recent decades. Here we synthesized 485 paired effect-size records from 56 peer-reviewed studies published between January 2000 and January 2024 to quantify changes in soil organic carbon (SOC) and tree biomass following conversion from coniferous forests (CF) to mixed coniferous-broadleaf forests (MF) and broadleaf forests (BF). Subgroup analyses and exploratory continuous-moderator regressions were used to examine variation associated with soil properties, climate, and geography. The results showed that conversion from CF to MF and BF significantly (p < 0.01) increased SOC by 30.32
Forest degradation assessments grounded in measurable structural indicators provide a more reproducible basis for management decisions than qualitative field classifications alone, particularly in ecologically diverse forest systems. Based on data from the first National Forest Inventory of Georgia (2019–2021), we clustered samples into eight forest formations using a phylogenetically informed approach and compared stand structural indicators across field-assigned degradation severity classes within each formation. Indicators quantifying stand stocking, structure, and productivity were compared across severity classes using non-parametric tests with post-hoc pairwise comparisons. Across formations, significant structural differences relative to undisturbed conditions were detected in 52
Forests are critical for sustaining water conservation services, yet the hydrological impacts of specific forest management practices remain poorly quantified, particularly in temperate broadleaved forests. Addressing this knowledge gap is essential for the development of evidence-based strategies for balancing ecological integrity and human water demands. Consequently, the present study investigates how three distinct and operationally defined forest management practices (Target tree forest management (TTFM), Structure-based forest management (SBFM), and Secondary forest comprehensive silviculture (SFCS)) influence soil-litter water-holding capacity (WHC) in Quercus aliena var. acuteserrata forests. It further evaluates the relative roles of forest structural attributes versus understory vegetation traits in regulating WHC. We established 16 plots (four replications per treatment, including a control) in northwest China. Forest structure was quantified via spatial structure parameters (uniform angle index, mingling index, and dominance index), structure diversity index and canopy index, while understory vegetation was assessed through species diversity indices and biomass. Redundancy analysis (RDA), Pearson correlation analysis and partial least squares structural equation modeling (PLS-SEM) were used to identify and quantify the key drivers of WHC variation. All three forest management practices significantly enhanced soil-litter WHC relative to the control, although the magnitude of improvement varied among treatments. Moreover, forest structure had a greater impact on WHC than understory vegetation. Among the treatments, SBFM showed the strongest performance in improving WHC. Additionally, shrub diversity, spatial structure, and litter reserves were identified as key influencers in RDA, with interactive and pathway dependent effects on WHC. Overall, these findings suggest that targeted refinement of forest structural attributes, together with appropriate regulation of understory vegetation, can enhance soil-litter WHC in temperate secondary forests. This study highlights the importance of conceptually consistent and site-specific forest management strategies for sustaining forest hydrological functions and ecosystem services.
The translocation and allocation of carbon (C) and nitrogen (N) within tree crowns play critical roles in enhancing resource-utilization efficiency, tree growth, and development. However, understanding of these processes, which are essential for determining effective crowns and guiding proper pruning practices, remains incomplete. Here, we conducted in situ isotope tracing experiments on six-year-old Betula alnoides trees using two stable isotopes (13C and 15N) to investigate the patterns of C and N translocation and allocation across different crown layers in the growth season. The relative abundances of foliar 13C and 15N in each crown layer were monitored over a 28-day chase period (at 0, 1, 3, 5, 7, 14, and 28 days post-labelling). Translocation of newly assimilated C among crown layers was limited in the growth season, supporting the theory of branch autonomy for C. While newly root-absorbed N was preferentially allocated to the upper crown layers, leaf-absorbed N was primarily translocated between adjacent layers, with the lower layers acting as the primary nutrient storage sites. These distinct utilization patterns, namely C autonomy within each crown layer and N interdependence via adjacent-layers translocation and lower-layer storage during the growth season, provide novel insights into the functional roles of crown layers and offer a scientific basis for optimizing artificial pruning regimes to promote the efficient cultivation of large, knot-free timber in forest management.
Silvicultural treatments, such as thinning and clearcutting, significantly alter belowground forest processes, yet post-treatment forest ecology remains poorly understood, particularly within temperate mixed and broadleaved forests. Ten years after silvicultural treatments, we investigated fine root biomass (FRB), soil properties, microbial parameters (microbial biomass, mycelium production, potential decomposition) and vegetation cover (canopy, shrub, herb), in Dinaric fir-beech forests on high karst plateaus of Slovenia. We compared these parameters in 27 plots including control, thinning (50
The ecosystem service (ES) concept and their non-monetary socio-cultural valuation is less established for forests than for landscapes. We assessed 15 ESs including provisioning areas and flows of an urban and a rural municipal forest (Augsburg, Germany). For valuation, we used stakeholder elicitation (label: All.stakeholders), categories of well-being (MEA), range of benefiting areas (Place.of.use) and Number.of.users and assessed their agreement for ES values, cluster-based ES bundles and ES multifunctionality using the Simpson diversity index. The urban and rural forest provided seven ESs (arithmetic mean) per pixel (arithmetic mean range: three to 13 ESs) and 242 different spatial combinations of ESs (ES bundles). Different non-monetary socio-cultural valuation approaches of ES created partially deviating rankings for the different indices (ES value and bundles or multifunctionality of ES). The valuation approaches hardly changed ES values and multifunctionality, both regarding their respective levels and their spatial configuration. ES bundles more strongly differed between the valuation approaches and the unweighted case without valuation. The valuation options prioritized other ESs than timber for most bundles in the urban forest and partially in the rural forest. The valuation options hardly changed the value of timber. Timber stayed relatively important in the rural forest and hardly important in the urban forest. Interestingly, the All.stakeholders, MEA, and Place.of.use valuation strongly agreed. The agreement of valuation approaches may partially question (local) stakeholder elicitation approaches provided the associated effort. The Number.of.users case showed the strongest differences. The parallel use of different valuation options may increase the validity through triangulation.
Bark beetle-fungal associations are critical drivers of forest health, yet the factors structuring these communities in Central European pine forests remain poorly understood. This study characterises and compares the culturable filamentous fungal assemblages associated with the epicuticle of two sympatric bark beetles, Ips acuminatus and Ips sexdentatus, infesting Pinus sylvestris in western Slovakia. Using culture-based methods and DNA barcoding, we identified distinct fungal assemblages associated with each beetle species. A total of 153 fungal isolates representing 15 species were obtained from 118 individuals of I. acuminatus, whereas 482 isolates representing 28 species were recovered from 209 individuals of I. sexdentatus. Ophiostomatoid fungi dominated the assemblages of both beetle species; however, their dominance structure differed markedly. Communities associated with I. acuminatus were strongly dominated by Graphilbum acuminatum, resulting in a comparatively uniform fungal assemblage. In contrast, I. sexdentatus harboured a significantly more diverse and heterogeneous community characterised by several co-dominant ophiostomatoid taxa. Both beetle species were also associated with entomopathogenic fungi and diverse saprotrophic taxa. Individual beetles of I. sexdentatus harboured significantly higher fungal alpha diversity than those of I. acuminatus, while beta-diversity analyses revealed pronounced differences in fungal community composition between beetle species, along with temporal variation within each host species. Notably, Graphilbum species (G. acuminatum, G. furuicola, and G. sexdentatum) were recorded for the first time in Slovakia, while Sporothrix pseudoabietina represents the first record of an Ips-associated occurrence in Slovakia. These results indicate that bark beetle identity is associated with differences in culturable filamentous fungal assemblages, although temporal variation and sampling context may also contribute to community structure.
Forest communities are experiencing an increasing rate of disturbance that affects their long-term stability. Functional trait composition and diversity play a crucial role in forest functioning, and hence can influence temporal stability, with consequences on resilience. In this study, we examined the role of functional trait composition and diversity, along with climate and vegetation structure variables, in determining the stability of forests in Catalonia (Northeastern Spain). We used functional trait and vegetation structure data from the ecological forest inventory of Catalonia, and calculated the temporal stability of tree productivity across 548 plots over a 20-year period (2000–2019) using NDVI data from the MODIS sensor on the TERRA satellite. Results showed that water availability and thermal amplitude had the strongest effects on stability. The community-weighted mean (CWM) of wood density (WD) positively influenced forest stability, whereas the CWM of leaf mass per area (LMA) and leaf biomass-to-sapwood area ratio (BL:AS) had a negative effect. Additionally, functional richness and dispersion, calculated using all studied traits, positively influenced stability. These findings suggest that the presence of both stress-tolerant (conservative) species and stress-intolerant (acquisitive) species enhances long-term forest stability, and, more generally, that functionally diverse forests are more stable.
Accurately Crown asymmetry is a common morphological response to heterogeneous environmental pressures, and this asymmetry directly influences the physiological processes of tree growth. Advances in UAV-Lidar technology have facilitated the acquisition of high-precision crown data, providing new pathways to characterize crown structural variations and investigate their impacts on tree growth. In this study, we propose a novel crown asymmetry index (Ihctsa), based on UAV-LiDAR data and time-series tool, to characterize crown asymmetry. Using a Cunninghamia lanceolata plantation in southeastern China as a case study, we analyzed the size-dependent effects of crown asymmetry on tree growth. The results revealed a significant reversal in the effect of crown asymmetry as tree size increased. Specifically, crown asymmetry exhibited a significant negative effect on the growth of small DBH trees, whereas it showed a significant positive effect on the growth of large DBH trees. Compared to the traditional Mean Circularity Index (IMC), the Ihctsa index captures the structural characteristics of crown variations and can determine the DBH threshold value (≈ 19.77 cm) for growth response at which transition from negative to positive. Furthermore, the LiDAR-based crown overlap index (CI2) demonstrated superior methodological suitability for separating thinning effects compared to the classic Hegyi index (CI1). This study demonstrates the feasibility and effectiveness of utilizing LiDAR for spatial competition analysis, providing a new methodological reference for forest ecology research.
Heavy forwarders can cause rutting and compaction when operating on wet or soft soils, limiting harvest opportunities in boreal forests to periods with frozen soil. This study applies a mechanistic soil trafficability model, integrating forwarder specifications, soil mechanical properties, and long-term climate data, to evaluate operational feasibility under Finnish conditions. Monte Carlo simulations were used to examine the sensitivity of trafficability predictions to variability in soil mechanical parameters. Results show that coarse mineral soils generally sustain traffic without frost, whereas fine-textured soils and peatlands require frozen conditions. Model-derived threshold frost depths ranged from 0.02 m in clay to over 0.30 m in mud, representing minimum values required for trafficability under idealized single-pass conditions. Interannual variability significantly influenced operational windows. Friction angle dominated trafficability variability in mineral soils, while cohesion was critical in clay and peat soils. Comparisons with the Finnish Forest Centre’s operational map revealed general agreement, while the mechanistic approach provides insight by quantifying parameter sensitivity and capturing seasonal dynamics. The results are based on model simulations and no independent field validation is included. These findings provide a framework for understanding soil trafficability constraints and support planning of winter harvesting operations under variable and changing climatic conditions.
Dispersed retention supports ecosystem functioning, forest continuity and biodiversity, highlighting the need for management strategies that promote long-term retention tree survival. We studied effects of tree- and stands-level variables on retention tree survival in coniferous and deciduous hemi-boreal forests. As tree mortality is driven by various factors, we evaluated their position (i.e., lying or standing) which indicates the root cause of mortality. In 344 clear-cut stands, we surveyed 4,442 retention trees of ten species. To explore the impact of variables, data were analysed by fitting Generalized Linear Mixed Models (GLMMs). Results showed that probability of survival varied among species. The highest probability of survival was observed in Acer platanoides, Tilia cordata and Alnus glutinosa, while the lowest was in Betula pendula and Populus tremula. Larger diameter significantly increased survival for Pinus sylvestris and Betula pendula. Increasing height-to-diameter ratio had a significant negative effect for survival of Pinus sylvestris, Populus tremula, Alnus glutinosa and Betula pendula. Site type was an important predictor of tree mortality. Trees retained on sand or sandy loam soil had higher mortality compared to loam, clay or binary soil. The forms of dead retention trees varied among species. Majority of Quercus robur and Pinus sylvestris dead trees remained standing, while most of Tilia cordata and Populus tremula formed lying deadwood. Besides the species identity, increasing tree height led to greater number of lying trees. Our results suggest that retention tree survival was strongly associated with species identity, tree size and site type.
Chinese tallow (Triadica sebifera) is a menacing invasive tree species in the southeastern United States (US), posing serious ecological and economic threats. Despite numerous regional-scale studies, little research has examined methods to understand localized drivers of tallow density, particularly in the pine flatwoods of coastal Mississippi. This study evaluated five statistical models, Linear Regression (LR), Spatial Autoregressive Error Model (SEM), Spatial Autoregressive Lag Model (SLM), Conditional Autoregressive Regression model (CAR), and Geographically Weighted Regression (GWR) with Gaussian and bisquare kernels, to compare their performance in predicting tallow density across a 4.75 km2 area within the Mississippi Sandhill Crane National Wildlife Refuge. Field data from 219 quadrats were aggregated at the patch level. A significant spatial autocorrelation (Moran’s I = 0.12 ,p-value = 0.005) justified the use of spatial models. GWR with a bisquare kernel yielded the best performance (AIC = 27.24), followed by the CAR model (AIC = 28.62), both of which effectively captured localized spatial patterns and reduced residual autocorrelation. Tallow density was associated with lower elevation, frequently moist soils, and moderate pine midstory, conditions favorable for seed dispersal and seedling establishment. Integrating local-scale spatial models with ecological field data can inform targeted management strategies in vulnerable coastal ecosystems.
In the tropical forests of Amazonia, logging is a vital part of local economies. Nevertheless, logging entails soil disturbance which could potentially and adversely affect soil organic carbon (SOC) pools. Skid trails cause most of the soil disturbance at logged sites, but is it enough to alter SOC stocks long-term? Thus, the present study sought to clarify this question by investigating 15- and 25-year-old skid trails to assess potential impacts to the below-ground carbon pool. In this endeavor, ten skid trails and five control plots in undisturbed old-growth forest were evaluated by sampling forest floor litter, soil bulk density, soil texture, pH and SOC in four depths of 0–5, 5–10, 10–20 and 20–30 cm. Results presented SOC accumulation when concentrations were measured in the surface of 25-year-old skid trails. Yet, when accounting for soil bulk density increases to calculate SOC stocks, between all sites, including undisturbed old-growth forest, the differences appear to be inconsequential, at least in the topsoil. Additionally, recovery of soil bulk density occurred to a depth of 20 cm under the skid trail tracks, although soil compaction was still encountered at 30 cm depth after 25 years. Thus, the aim of logging operations should be to minimize the amount of skid trail construction when entering unlogged forest and reuse existing skid trails when reentering logged forest to minimize potential impacts to SOC pools, especially with impacts to SOC in the subsoil still unknown.
Tree height is a key variable for assessing forest functioning and resources (e.g. volume, carbon stocks) at both tree and stand levels. However, direct field measurements are costly and time-consuming. Developing accurate and unbiased height-diameter allometries applicable over large spatial scales is therefore crucial for forest research and management. Based on the French National Forest Inventory, with 269,460 tree-height observations on 49,120 plots measured, we developed generalized, species-specific height-diameter allometries that integrate stand dendrometrical characteristics and stand structure. The models cover 41 European tree species and the four main stand structures: even-aged, uneven-aged, coppice-with-standards and coppice. We provide a recalibration method that practitioners can optionally use, directly on the field, to enhance local accuracy. This method, used at plot level, assesses how many additional trees should be measured and which ones to select to maximize the improvement of the model, by keeping the method easily usable on the field. By integrating basal area as stand density and quadratic mean diameter as an indicator of stand development stage, our models enable us to assess the influence stand dendrometrical characteristics on these allometries and evaluate how different species responded to competition. Results indicate that with increasing competition, tree height tends to be higher for a given diameter, and that stand structure significantly influences 28 out of the 41 species. Local recalibration showed that measuring just one to six trees (among the largest and thinnest diameter) per plot reduced prediction error by 10–70
Understanding how biodiversity responds to forest management is a key challenge for sustainable forest management. Birds, as a sensitive taxon of habitat quality, provide valuable insights into the ecological consequences of different management types. In this study, we examined how even-aged (EA) and uneven-aged (UEA) management strategies, and their associated management stages influence bird communities in managed Scots pine (Pinus sylvestris) forests. We assessed species richness and abundance of forest specialists, generalists, and ecological guilds, and compared the relative explanatory power of management strategy, management stage, and forest structural attributes using data from 207 plots. UEA stands generally favoured forest specialists and forest generalists as well as cavity and understory nesters, and overstory and understory foragers. Bird communities varied among management stages: EA young stands showed the lowest values of forest specialists, cavity nesters and trunk and understory foragers, while UEA capitalized and EA preparatory cutting stages hosted the highest values of forest specialists and favoured cavity and overstory dependent guilds. Overall, management stage models better explained the variation in bird community than management strategy and structural variables models. We highlight that management stage played a decisive role in shaping avian communities. Ultimately, whether under EA or UEA systems, forest management should adopt a multifunctional approach that prioritizes biodiversity-relevant stages, enhances stand heterogeneity, and ensures the long-term conservation of forest biodiversity.
As a crucial component of natural infrastructure, integrating the ecological service functions of urban forests into urban design remains a significant challenge. Given that the stand types of urban forests serve as a pivotal landscape attribute within this infrastructure, this study recruited 300 participants and randomly assigned them to six types of virtual landscape scenarios, aiming to systematically analyze the visual behavior patterns and restorative potential of in-forest landscapes. The data were analyzed using R version 4.4.0, and the main findings included as follows: (1) The sunlight, plants and colors within in-forest landscape spaces could attract the participants’ visual attention. (2) Compared to mixed forests, pure forests tended to reduce cognitive load, however the participant generally showed a higher willingness to explore mixed forests. (3) Landscapes containing coniferous trees were more effective in emotional restoration than those dominated by broad-leaved trees. These results indicated that in-forest landscapes held considerable potential for promoting physical and mental health. In the future, by scientifically adjusting forest stand types, we could optimize the distribution of participant visual focus, thus effectively enhancing their well-being and providing a theoretical foundation for constructing a high-quality, health-centric urban forest landscape system that supports sustainable landscape resource utilization.
