Forest Ecology and Management

Deadwood is a fundamental component of forest ecosystem, supporting biodiversity and driving multiple ecological processes. However, structures that may develop on downed coarse woody debris (CWD) create additional microhabitats that are used by numerous organisms and contribute to small-scale habitat heterogeneity. To date, quality of CWD is commonly characterized by its volume, diameter, tree species or stage of decomposition, while fine-scale structures occurring there remain not surveyed and their role in ecosystem is rarely quantified. Here, we introduce the novel concept of microhabitats on CWD. i.e. Deadwood-related Microhabitats (DreMs), defined as distinct features occurring on CWD that may provide shelter, breeding or foraging sites for forest-dwelling organisms. Using an original catalogue comprising 14 groups and 30 types, we inventoried DreMs on 6,003 CWD across 423 study plots located in best-preserved old-growth forests in Poland. We quantified the frequency and richness of DreMs and assessed the link between CWD characteristics and DreM richness in spruce, beech, willow-poplar, fir-beech and oak-lime- hornbeam forests. All inventoried DreMs occurred on both deciduous and coniferous taxa. The most frequent DreM included bryophyte mats, loose bark patches, insect galleries, fungal fruiting bodies and polypores. DreM richness increased with CWD diameter, more complex architecture and the presence of multiple decay classes within single debris. DreM richness peaked at intermediate decay classes and was higher on deciduous than on coniferous taxa. Our study is the first large-scale qualitative and quantitative assessment of DreMs in temperate forests. By focusing on forests characterized by ecological continuity and minimal human-related disturbance, the results provide a reference for downed deadwood-associated structures. By complementing inventory of tree-related microhabitats, DreMs extend potential monitoring schemes of habitat quality and contribute to biodiversity-oriented forest management. Highlights* Downed coarse woody debris (CWD) hosts Deadwood-related microhabitats (DreMs) * Higher DreM richness is associated with CWD diameter * DreM richness peak at intermediate stages of wood decay * CWD of deciduous taxa support more DreMs than coniferous * Diversified CWD and DreMs increase habitat heterogeneity for forest-dwelling taxa

Internal decay in living trees is an important component of carbon and nutrient cycling as well as species and structural diversity maintenance in forest ecosystems. We used sonic and electrical resistance tomography to evaluate and compare the prevalence and severity of stem decay in 57 living trees among four common species (Acer rubrum L., Nyssa sylvatica Marsh., Quercus rubra L., and Tsuga canadensis (L.) Carriere)) with overlapping and non-overlapping distributions across wetland and upland habitat types at the Harvard Forest in Petersham, MA, USA. Independent of tree size, site identity best explained variation in the prevalence of decay across trees sampled, whereas species identity best explained the severity of decay. We categorized trees as having no decay, incipient decay, active decay, or cavities based on combined sonic and electrical resistance metrics, the latter generated by a custom image analysis application. About 31% of wetland trees exhibited incipient decay (compared to 11% in the upland), whereas about 32% of upland trees exhibited active decay (compared to 10% in the wetland). Our study highlights a new quantitative framework for decay categorization through normalized principal component analysis (PCA) and decay analysis software that complements dual tomographic methodology for future investigations of ecological drivers of decay presence and susceptibility.

O_LIDuring the extreme drought period of 2018-2020, secondary pest attacks were observed in some declining beech trees (Fagus sylvatica). The main species identified are Agrilus viridis and Taphrorychus bicolor, which are known to attack beech trees more frequently after periods of intense drought. The aim of this study is to investigate if and how these two cambium-feeding insects in interaction with drought contribute to beech decline. We assessed the modification of the carbon reserves stock and carbon allocation to growth and fruiting in declining beech trees. C_LIO_LIPast radial growth, non-structural carbohydrates (NSC) concentrations in several organs and the quantity of beechnuts were measured in 38 beech trees with contrasting levels of biotic attack in 2020. Total amount of carbon reserves was calculated on the basis of NSC concentrations, and the amount of carbon allocated to growth and fruiting at the tree level was assessed using allometric relationships. C_LIO_LIBeech trees most severely attacked by secondary pests showed lower radial growth for last ten years than trees that have not been attacked. NSC concentrations and the amount of carbon reserve in the coarse roots and stems of trees were also lower in beech trees with intense biotic symptoms compared to unaffected trees. However, the amount of carbon allocated to growth and fruiting during the 2020 growing season did not differ significantly among biotic attack classes. C_LIO_LISynthesis: Regardless of biotic attack intensity, declining beech trees exhibited abnormally low carbon reserves. Trees most severely affected by insects in 2020 appeared to be the most vulnerable, as evidenced by reduced radial growth over the past decade. Future experiments are needed to explore further whether insects impacted directly carbon reserves, or whether low carbon reserves in trees is a vulnerability factor promoting insects attacks. Finally, declining beech trees allocated a similar amount of carbon to fruiting as reported in healthy stands, suggesting that fruiting is a prioritised carbon sink, even under severe drought and biotic attack. C_LI

Tropical rainforests generate and maintain their own microclimate regimes and the resultant cooler, more humid and stable environments foster the hyperdiversity typical of these ecosystems. Although the temporal and spatial (horizontal) distributions of microclimates have been relatively well studied, the vertical dimension has received less attention, and little is known about how forest disturbance affects the vertical stratification of microclimates in tropical forests. In this study, we examine how the vertical distribution of temperatures varies between undisturbed and burned Amazonian forests. We installed five vertical transects with temperature dataloggers distributed at 7 different heights to collect data over multiple days during the end of the dry season. We investigated how anthropogenic disturbance (fire) mediates the vertical stratification of microclimate and whether microclimate buffering (i.e, the difference between understorey and canopy temperatures) varies according to the forest structure. We showed that anthropogenic disturbance can cause an inversion in the vertical stratification of microclimates, with burned forests having hotter temperatures (up to 2 {degrees}C) in the understorey than in the canopy during the day - the opposite of what is found in undisturbed forests (typically 3 {degrees}C cooler). During the night, while understorey and canopy temperatures are similar in undisturbed forests, we found that, in burned forests, understorey temperatures were up to 2 {degrees}C cooler than in the canopy. Microclimate buffering by day was best explained by aboveground carbon stocks, with higher temperature buffering in more carbon rich forests. Our study shows that anthropogenic disturbance alters the vertical stratification of temperatures in Amazonian forests, leading to significant temporal changes along the diel cycle. Future research should focus on understanding these changes across a wider range of disturbance regimes, and explore the consequences for biodiversity and ecosystem functions from the canopy to the forest floor.

Elevational gradients provide a framework for understanding how environmental filtering reorganises communities and interactions, but plant-pollinator interactions along temperate forest elevational gradients remain overlooked. We studied early-spring understorey communities at four forest sites spanning the foothills towards the timberline (450-1,000 m a.s.l.) in the Krkono[s]e Mountains, Czechia. Across six transects per elevation, we quantified flowering plant species richness, floral resources and traits, and video-recorded flowers, yielding 4,003 pollinator visits. We analysed elevational patterns in species richness, community composition, floral traits, and quantitative network characteristics. Visitation frequency and flowering plant and pollinator species richness peaked at intermediate elevations. The contribution of dipteran relative to hymenopteran pollinators increased towards higher elevations, principally because of non-hoverfly flies, whereas individual bee groups showed no uniform response. Floral resources and traits showed no uniform elevational responses, although total nectar sugar availability peaked at the highest site because of the dominant Vaccinium myrtillus. Most notably, both network-level specialisation and mean species-level specialisation were generally greater at the two higher elevations, whereas nestedness was lower and other network characteristics showed no consistent patterns. These findings suggest that shifts in pollinator composition and dominant floral resources potentially shaped interactions along the gradient. The increasing specialisation with elevation contrasts with the generalisation often expected under reduced partner availability and indicates that forest networks may follow elevational patterns not predicted from open habitats. Despite limited site-level replication, this study provides, to our knowledge, the first community-wide characterisation of plant-pollinator interactions along a temperate forest elevational gradient and identifies patterns requiring evaluation across replicated gradients.

BackgroundMangrove forests are crucial ecosystems which support biodiversity, protect coastlines and store vast amounts of carbon. Mangrove conservation and protection rely on accurate carbon accounting to unlock investment. However, the allometric equations underpinning these carbon estimates remain poorly constrained, particularly for the large trees. MethodsWe used terrestrial laser scanning (TLS) to estimate the biomass of 187 mangrove stems across Suriname, Panama, Colombia and Jamaica, including 84 stems >20 cm DBH. TLS-derived biomass estimates were used to evaluate local, regional and pantropical allometric equations. ResultsMost diameter-based allometric equations underestimated biomass by 8-65%. Equations additionally incorporating tree height performed better, but still underestimated biomass by 12-16% on average. Applying alternative allometries to a representative mangrove inventory from Panama produced biomass estimates ranging from 80 to 200 Mg ha-{superscript 1}, demonstrating that allometric uncertainty alone can generate more than a two-fold difference in estimated carbon stocks. ConclusionsCurrent allometric equations systematically underestimate the biomass of large mangrove trees and are therefore likely to underestimate mangrove carbon stocks. TLS provides a practical, non-destructive approach for expanding biomass datasets and improving allometric equations. Reducing allometric uncertainty should be a priority for strengthening blue carbon accounting and mangrove conservation.

Direct heat damage has been considered secondary as a cause of climate change-induced tree mortality and productivity declines in forests compared with climate change effects on tree water relations. However, evidence from temperate and tropical forests is accumulating that direct heat damage in the photosystem II (PS II) that is independent of water relations is also a realistic scenario under climate change. We analyzed PS II heat tolerance in Larix sibirica, which represents a dominant boreal tree species in Siberia and northern Central Asia in cold environments with subzero or near-zero mean annual temperatures, but nevertheless warm summers. Thermal imaging was applied to relate heat thresholds found in the laboratory to canopy temperatures in forests on north-facing mountain slopes, which are the main habitat of L. sibirica. L. sibirica showed slight decreases of the maximum quantum yield of PS II (Fv/Fm) at 35{degrees}C and 40{degrees}C after up to 4 h, but strong reductions at [≥]45{degrees}C and minor increases in Fv/Fm in late summer, which could be interpretation as heat acclimation. Canopy temperatures in the study year did not reach the thresholds for serious PS II heat damage. However, L. sibirica was more strongly sensitive to heat than temperate conifers. This first combined study of heat tolerance and canopy temperatures from boreal forests points to the possibility of low heat tolerance of boreal tree species, but such conclusion would require the study of more tree species.

O_LIForests are vertically structured ecosystems where light attenuation, microclimatic buffering and resource availability occur along continuous gradients from the canopy to the understorey layers. Despite this complexity, studies rarely integrate trophic interactions across vertical layers, overlooking how vertical forest structure shapes consumer communities through abiotic and biotic pathways. C_LIO_LIIn this study, we combined layer-specific measurements of plant diversity, structure and microclimate with arthropod sampling in the canopy and understorey, as well as bird survey data, in a temperate forest. Applying Bayesian structural equation models with explicitly defined directional pathways, we modelled both consumer biomass and abundance across trophic levels and vertical layers. C_LIO_LIAbundance measures were predominantly filtered by local layer conditions, while biomass responded to conditions across layers, reflecting stand-level energy flow. This suggests that these two metrics capture fundamentally different ecological processes. Canopy conditions consistently predicted understorey arthropod abundance across trophic levels, while the reverse was not observed, suggesting a strong asymmetric downward propagation of canopy-driven effects. Furthermore, trophic interactions between arthropod primary and secondary consumers remained largely stratified within vertical layers, suggesting a vertical food web compartmentalisation rarely shown in structurally complex aboveground systems. C_LIO_LIPlant diversity, structure and microclimate shaped consumer communities mainly through the modulation of resource availability and plant apparency, with effects varying across vertical layers, trophic levels and taxonomic groups. Through complementary mechanisms, plant diversity likely determined the variability of resources available to consumers at different trophic levels. Structural properties, in contrast, potentially drove the spatial redistribution of these resources through light attenuation and microclimatic buffering, which in turn influenced the physiological capacity of consumers to access and exploit available resources. C_LIO_LIThese findings demonstrate that vertical stratification mediates trophic pathways in a highly directional manner, with canopy characteristics playing a disproportionate role in structuring the forest community across layers. Integrating layer-specific structural and trophic indicators into forest biodiversity assessments and management strategies is therefore essential to fully evaluate biodiversity dynamics and multifunctionality in structurally complex forest ecosystems. C_LI

Tropical Atta leafcutter-ant colonies reach a maximum lifespan of 15-20 years because each colony has only a single queen, queens live for maximally 15-20 years, and colonies do not requeen after queen death. At the northern range limit of leafcutter ants in Louisiana, however, we found that the mortality rate of Atta texana colonies is consistent with a life expectancy of 65-75 years and a maximum colony lifespan exceeding 100 years. Annual mortality of established A. texana colonies in Louisiana is only 1-2% compared to 10-25% in tropical Atta species. Exceptional longevity of A. texana colonies is due to (i) absence of Nomamyrmex army-ant predators specialized to raid Atta colonies; (ii) polygyny of A. texana colonies, creating a unique social organization in A. texana colonies that differs from the monogynous colonies typical for all other Atta species; and (iii) adoption of young queens by old colonies, possibly facilitated by low genetic diversity in range-limit populations of A. texana. Centenarian longevity of A. texana colonies was so far unknown because, from the 1930s to the turn of the century, research prioritized eradication of A. texana as a forestry pest, and landscape-wide pesticide application by aircraft eliminated old A. texana colonies. After the most harmful pesticides were banned 30-50 years ago, A. texana populations recovered, yet A. texana required decades to regain its earlier niche in the forest ecology. In undisturbed habitat, well-established old A. texana colonies with large territories appear to recruit young queens especially well. Old age of a colony therefore does not necessarily increase mortality as in typical lifespan-limiting processes where age drives senescence and mortality (old age [->] mortality); instead, well-rooted residency that is correlated to age of an A. texana colony increases the chance of rejuvenation via queen adoption, reduces or eliminates reproductive senescence of a colony, and consequently prolongs colony lifespan (well-established residency [->] rejuvenation [->] long life). Large size attained in old age imparts potentially unending life.

This report presents a field assessment of wild Coffea eugenioides, the diploid maternal progenitor of cultivated Arabica coffee, in Nyungwe Forest National Park and the adjoining, isolated Cyamudongo forest fragment in south-western Rwanda. The assessment targeted trees identified as candidate mother trees (individuals bearing fruit and therefore potential seed sources): 59 such trees were georeferenced and measured for structural, phenological and reproductive traits using a structured KoBoToolbox questionnaire (reproduced in Annex 1). The work was undertaken to inform the establishment of a seed orchard for this species under the RTRP-Seed (IKI) and TREPA (GCF) projects implemented by Landscape Alliance (CIFOR & ICRAF in action). On C. eugenioides, the cherry is the fleshy fruit that contains the seed, so cherry load is a direct measure of fruit and seed output. Reproductive output across the assessed trees is low, highly variable and weakly related to tree size. The median tree carried an estimated 29 cherries in the whole canopy, 31% of trees carried 15 cherries or fewer, and the coefficient of variation in cherry load exceeded 110%. Tree size explained little of this variation (stem diameter, the single significant structural predictor, accounted for under 10% of the variance; r = 0.31). Trees in the isolated Cyamudongo fragment carried significantly fewer cherries than those in the main Nyungwe block (medians 15 vs 32 cherries; Mann-Whitney p = 0.021), and every observation of sub-optimal on-tree seed quality occurred in the fragment. Low and asynchronous fruiting, together with the reduced fruit and seed set typical of small, isolated populations, makes large-scale seed collection an unreliable basis for an orchard. The original plan was to collect seed from wild trees and raise a Breeding Seed Orchard (BSO). On the evidence presented here, that plan should be redirected toward a Clonal Seed Orchard (CSO): rather than collecting seed, scions (budwood) are taken from selected wild trees and grafted onto vigorous local Rwandan Coffea arabica rootstock. This captures the full genotype of each selected tree, shortens the time to flowering, secures the germplasm of a threatened wild relative ex situ, and aligns with Rwandas restoration and climate commitments.

AimHere we aim to disentangle species-specific bioclimatic drivers of forest site productivity and project their future dynamics, providing a spatially explicit basis for anticipating climate-driven shifts in productivity and their implications for forest carbon sequestration. LocationIberian Peninsula. Time period1985-2014 (calibration); 2071-2100 (projected under CMIP6 scenarios). Major taxa studied21 Iberian tree species. MethodsWe used Site Form (SF) maps derived from the Third Spanish National Forest Inventory, spatially interpolating plot-level SF estimates as a continuous productivity index and relating them to 25 bioclimatic variables. Multiple linear regression models were selected via complementary stepwise and subset regression and validated on independent hold-out data (80%/20% split). ResultsValidated [Formula] ranged from 0.46 (Quercus faginea) to 0.97 (Pinus pinaster); 17 of 21 species reached [Formula]. BI013 precipitation of the wettest month), not BI014, was the most frequently retained predictor (15/17); BI014 was retained in only (11/17 models with a near-even sign split. Combining projected changes in mean productivity and habitat extent under SSP5-8.5, fifteen of sixteen applicable species lose total productivity by 2071-2100, six -- including Fagus sylvatica and Betula alba -- collapsing to below 1% of their reference-period value; only Pinus pinaster gains, and only under the lowest-emission pathway (up to 175%) -- under SSP5-8.5 it too loses productivity, albeit less than any other species (35% of its reference-period value retained). Limiting warming to SSP1-2.6 spares Mediterranean pine and oak species but not Euro-Siberian and montane ones. Main conclusionsThese validated, extrapolation-aware models reveal a near-universal, climate-driven collapse in Iberian forest site productivity, with direct implications for the carbon-sink potential currently attributed to these forest types, and provide a route to dynamic, climate-aware carbon-uptake estimates for the region.

Understanding the relationships between soil macrofauna and decomposition is crucial for predicting how land-use change impacts ecosystem function in fragmented systems. This is because soil macrofauna affect decomposition and also respond to the changes in abiotic conditions across habitat gradients. This study investigates edge effects on the macrofauna contributions to decomposition across forest-field ecotones. We used bait lamina assay to quantify aboveground and belowground feeding activity of soil macrofauna in Autumn 2025 in three deciduous forest-old field ecotones and one coniferous forest-old field ecotone, in Southwestern Ontario, Canada. Vegetation diversity and composition, LAI and soil characteristics (i.e., soil organic matter, pH, temperature and moisture) were measured at each plot along the ecotone. Pitfall trap data collected in Summer 2025 at the same sites were used to characterize macrofauna communities. We used generalized linear mixed effects models to estimate the effect of distance to edge, site, and depth into the soil on bait lamina consumption and soil macrofauna, with transect nested within site as random effects. Consumption activity increased with distance into the forest from the field, with the edge representing an intermediate; and, decreased with increasing depth into the soil. In contrast, soil macrofauna abundance, especially isopods, decrease with distance into the forest from the field. These trends varied significantly across sites, so that consumption activity and abundance sometimes remained constant across the ecotone (i.e., site x distance interaction). The results demonstrate that macrofaunal contributions to bait consumption varied along the ecotone, shaped by interacting environmental gradients and shifts in community composition unique to each site.

Tropical forest succession can reorganize biodiversity not only by changing species richness, but also by filtering the functional traits that represent ecological strategies. Harvestmen are highly sensitive to microclimatic and structural changes in Neotropical forests, yet their functional diversity remains poorly explored. We investigated taxonomic and functional diversity of harvestmen in a local scale, an Atlantic Forest remnant in southeastern Brazil containing forest patches at different successional stages. Standardized nocturnal active searches and leaf-litter sampling yielded 384 individuals belonging to 14 morphospecies. Functional diversity was quantified from four morphological traits using Hill numbers (q = 0, 1 and 2), morphofunctional ordination, beta-diversity partitioning and environmental models based on forest-structure variables and PCA-derived gradients. Functional diversity was highest when rare species were weighted equally and declined strongly from q = 0 to q = 2, indicating that uncommon species carried much of the regional morphofunctional variation. Functional alpha diversity was positively associated with taxonomic alpha diversity, and Mantel tests showed that taxonomic and functional dissimilarities among sampling points were significantly correlated. However, formal beta-diversity partitioning refined this interpretation: functional beta diversity was dominated by nestedness-resultant dissimilarity rather than turnover, suggesting that functionally poorer assemblages represented contracted subsets of the regional trait space. Morphofunctional analyses identified compact, robust and long-legged species groups, and environmental models showed that lower vegetation structure, litter depth and forest-maturity gradients significantly influenced functional diversity. These findings indicate that mature, structurally complex Atlantic Forest patches help maintain the full spectrum of harvestman morphofunctional strategies and highlight harvestmen as promising models for trait-based conservation ecology. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/731358v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@1f91597org.highwire.dtl.DTLVardef@1f89aa6org.highwire.dtl.DTLVardef@7141b8org.highwire.dtl.DTLVardef@191accc_HPS_FORMAT_FIGEXP M_FIG C_FIG

Accurate tree volume estimation is central to forest management and carbon accounting. Allometric equations are widely used but limited in transferability across species, regions, and environmental conditions. Mobile Laser Scanning (MLS) offers a promising alternative through direct measurement of tree geometry; however, the influence of tree shape on MLS accuracy remains poorly understood. This study evaluated MLS-derived estimates of stem diameters, total tree height, and merchantable stem volume against destructive reference measurements from 176 trees spanning eight species (four hardwood, four softwood) in Wallonia, Belgium. A Zeb Horizon RT scanner was used; tree architectural descriptors extracted from the point cloud were tested for associations with measurement error. Across 7,824 stem diameter measurements, MLS achieved a mean error of 0.46 cm, with precision declining above 15 m. MLS-derived height outperformed Vertex IV clinometer measurements for hardwood species (RMSE% = 6.88 vs. 8.78) but performed slightly less well for softwoods (RMSE% = 7.36 vs. 6.14). QSM-based volume estimates systematically underestimated reference values, while taper-based reconstruction produced nearly unbiased estimates with an RMSE of 15.72%. Correlation analyses and PCA showed that tree architectural variables explained only a small fraction of MLS error variability. Diameter and height errors were largely independent of structural attributes, while volume errors showed moderate associations with tree size and crown density. These findings indicate that tree architecture is not a primary source of MLS measurement uncertainty. Future MLS-based forest inventory efforts should prioritize acquisition and processing optimization, as scanning conditions and forest structure appear more influential than tree shape.

Global climate change has increased the frequency and intensity of drought events, making it urgent to understand how native species respond to water deficit (WD). In biodiverse environments such as tropical forests, simple methods are needed to study multiple species simultaneously. This can help predict how natural environments will respond to climate change and guide the strategic selection of drought-resistant species for reforestation. This study aimed to: (1) adapt an existing simple and inexpensive method to apply a controlled WD on tree seedlings from tropical species commonly produced in nurseries for restoration projects, suitable for greenhouse experiments; and (2) evaluate the effectiveness of this method in generating ecophysiological responses to WD that allow the estimation of species' drought resistance. Ten native tree species from the Semideciduous Seasonal Forest (SSF), a phytophysiognomy of the Atlantic Forest, were selected. An existing method was adapted to implement capillary irrigation, in which the bases of the seedling tubes were placed in floral foam blocks positioned inside 15 L plastic containers filled with water. A gradual and severe WD was applied to five seedlings of each species by removing all water from the containers, leaving only the water retained in the saturated floral foam available for plant uptake. The remaining seedlings were maintained well-watered (containers full and foam saturated) as the control group. Stomatal conductance (gs) was measured daily for all seedlings until they reached 50% or less of their initial gs (igs); at this point, stem water potential ({Psi}w) was measured. Both gs and {Psi}w differed significantly among treatments and species (p < 0.01). Ficus guaranitica and Heliocarpus popayanensis were the only species that did not show significant {Psi}w differences between treatments, indicating higher drought resistance. In contrast, Campomanesia xanthocarpa and Eugenia uniflora had the lowest {Psi}w values under WD, suggesting lower drought resistance. The remaining species were distributed along a gradient of responses to WD. Additionally, no correlation was found between {Psi}w and gs at 50% igs in the WD group (rho = 0.16, p = 0.26). The method proved effective in inducing controlled WD and generating measurable ecophysiological responses, offering a useful tool for screening native species for drought resistance.

O_LIThe heat tolerance of tree species has recently received increased attention, as it is critical for the response of forest ecosystems to climate change. Most studies rely on laboratory experiments with detached leaves, where the thermostability of photosystem II (PS II) is analyzed using chlorophyll fluorescence analysis. The temperature at which the maximum quantum yield (Fv/Fm) of PS II is reduced by 50% (T50) is often used as key measure of heat tolerance despite of weak mechanistic corroboration and inconsistent definitions. We propose a new metric consisting of a critical temperature (TIP) and a corresponding fluorescence value (FIP). C_LIO_LIWe analyzed the effect of incubation time and temperature on different versions of T50. C_LIO_LIT50 was strongly dependent on the duration of heat exposure, decreasing exponentially with incubation time. T50 and TIP values derived from short-term treatments of different incubation times <1 h are not comparable, but stabilize after longer intervals of heat exposure. C_LIO_LIT50 of Fv/Fm specified without considering incubation time is a meaningless metric. Specifications derived from short-term heat treatments should be avoided, because the result is highly influenced by the experimental setup. Different calculation methods for T50 influence the result and elucidate different aspects of the heat response. C_LI

Forests are essential to the global carbon cycle with light use efficiency (LUE) as a key parameter for assessing carbon sequestration capacity. However, the variations and drivers of LUE remain inadequately understood. Using remote sensing data, we analyzed global LUE patterns across five forest types and identified the main drivers. The global average annual LUE of forests is 0.93 {+/-} 0.36 g C MJ-1 during the period 2001-2022, with an increasing trend of 0.0034 g C MJ-1 yr-1. Among forest types, evergreen broadleaf forests exhibited the highest LUE, followed by evergreen needleleaf forests. Deciduous broadleaf forests and mixed forests showed similar levels, while deciduous needleleaf forests exhibiting the lowest LUE. Variations in LUE were jointly driven by plant traits and climatic conditions, with generalized linear models explaining 86% and 98% of spatial and temporal LUE variations, respectively. These findings highlight the critical role of plant traits and climate in shaping forest LUE, providing insights for enhancing carbon cycle models and informing forest management strategies in the context of global change.

Many rare saproxylic (deadwood-dwelling) beetles are among Europes most threatened insects, yet the relative importance of local microhabitat quality versus broad-scale landscape connectivity in shaping their genetic integrity remains poorly understood. We evaluated environmental drivers for 13 saproxylic beetle species--rare old-growth specialists, common taxa, and economically significant pests--across eight major forest complexes in Poland, using double digest restriction-site associated DNA sequencing (ddRAD-seq) paired with plot-level structural inventories and estimated effective migration surfaces (EEMS) modelling. A beta generalized linear mixed model identified deadwood diversity as the only significant within-species predictor of observed heterozygosity ({beta} = 0.041, 95% CI 0.0227-0.0586, p < 10-); total deadwood volume, forest age, time since logging, stump density, and veteran tree density were not significant. Management-category contrasts in observed heterozygosity (Ho) and the inbreeding coefficient (Fis) were non-significant after Tukey adjustment. Predictor x ecological-tier interactions did not differ detectably between rare and common species for five of six structural predictors; time since last logging was the exception ({chi}{superscript 2} = 4.56, p = 0.033). EEMS patterns differed among species and fell into three broad groups: regional lineage barriers, asymmetrical corridors, and surfaces close to isolation- by-distance expectations. These results associate plot-level heterozygosity with deadwood diversity and show that regional gene-flow patterns cannot be generalised across saproxylic beetles. Conservation planning should therefore combine local deadwood restoration with species-specific assessment of landscape connectivity.

AimsHistorical land use has shaped plant diversity in Central Europe for centuries, and many plant communities of high conservation value have been maintained by long-term traditional management. This study assesses how changes in land use over the past century have affected plant community composition and vegetation-based ecological indicator values in the management-dependent mire community Primulo-Schoenetum ferruginei. LocationSouth-western Germany. MethodsWe conducted repeated vegetation surveys at multiple sites, comparing historical records with recent surveys spanning up to 97 years. Changes in species composition were analysed using multivariate approaches, and shifts in habitat conditions were assessed using indicator values for nutrients, temperature, light and mowing frequency. Information on historical management was compiled from original vegetation sources, while current management data were obtained from responsible conservation authorities and regional administration. ResultsFen communities showed pronounced temporal changes in species composition. Community turnover was significantly associated with shrub encroachment, mowing frequency, hay transfer and early mowing. In addition, species-based indicator values suggested increasing nutrient availability and temperature affinity of the vegetation, alongside decreasing light availability. Disturbance indicators pointed towards less frequent but more severe disturbance regimes in contemporary compared to historical vegetation. ConclusionsOur results demonstrate that management-dependent fen communities are highly sensitive to changes in land-use regimes, i.e. disturbance frequency and severity that is indicated to have significantly changed in the protected areas in this study. These findings highlight the importance of maintaining traditional land management practices when aiming to maintain biodiversity in calcareous fens.

O_LIVeteran trees are biodiversity hotspots, providing a range of microhabitats, including tree hollows or rot holes in trunks, which support a large diversity of invertebrates including threatened species. Each rot hole is a unique microcosm, with variable biotic and abiotic characteristics enabling their use by many invertebrate taxa. C_LIO_LIMost previous studies describing the invertebrate communities of rot holes and the factors determining their structure focus on a narrow range of invertebrate taxa, and many host tree species remain unexplored. European ash (Fraxinus excelsior L.) is one of Europes most threatened deciduous tree species due to the spread of ash dieback disease, but the potential impact of these losses on the invertebrate communities that inhabit ash is poorly understood. C_LIO_LIInvertebrates were sampled and identified to family level from 14 sites across Wales and western England, and major physical characteristics of each rot hole and sample site were assessed (e.g., habitat type, altitude, maximum site temperature). C_LIO_LIAsh rot hole invertebrate communities were highly diverse with a range of threatened taxa, including some undescribed or new to the region. There was large variation in both measured rot hole characteristics and the invertebrate communities between individual rot holes, sites and habitats. Both tree-specific and biogeographical factors significantly influenced invertebrate diversity and community structure, suggesting that sustaining the heterogeneity of ash rot holes across a range of locations is required to support saproxylic invertebrate diversity. C_LIO_LIWith increasing ash veteran tree vulnerability, sustaining these vital habitats and their associated invertebrate communities is a conservation imperative. This study has demonstrated that considering heterogeneity in both habitat characteristics and landscape context will be crucial when conserving these communities. C_LI