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Summary: Capturing how tree growth and survival vary through space and time is critical to understanding the structure and dynamics of tree‐dominated ecosystems. However, characterising demographic processes at scale is inherently challenging, as trees are slow‐growing, long‐lived and cover vast expanses of land.We used repeat airborne laser scanning data acquired across 25 km2 of semi‐arid, old‐growth temperate woodland in Western Australia to track the height growth, crown expansion and mortality of 42 213 individual trees over 9 yr.We found that demographic rates are constrained by a combination of tree size, competition and topography. After initially investing in height growth, trees progressively shifted to crown expansion as they grew larger, while mortality risk decreased considerably with size. Across the landscape, both tree growth and survival increased with topographic wetness, resulting in vegetation patterns that are strongly spatially structured. Moreover, biomass gains from woody growth generally outpaced losses from mortality, suggesting these old‐growth woodlands remain a net carbon sink in the absence of wildfires.Our study sheds new light on the processes that shape the dynamics and spatial structure of semi‐arid woody ecosystems and provides a roadmap for using emerging remote sensing technologies to track tree demography at scale. [ABSTRACT FROM AUTHOR]

There is an urgent need for woodland expansion to help enhance and restore vital forest ecosystem services. However, the process of natural regeneration of woodlands is often slow, requiring active reforestation approaches. Factors limiting regeneration are complex, but there is increasing evidence that natural woodland expansion onto sites that have been treeless for a long period of time may be limited by the loss of microbial woodland‐soil properties. This study explored a potential role for mycorrhizal associations in facilitating obligate ectomycorrhizal (ECM) tree establishment, with potential implications for active reforestation practices. We determined the spatial distribution patterns of ECM tree seedlings – Pinus sylvestris and Betula spp. – outwith a woodland, in relation to existing dual‐mycorrhizal Salix plants. There was very strong evidence that ECM tree seedlings were more likely to be found growing within groups around Salix than as isolated individuals, supporting the view that Salix drives the current spatial distribution patterns of ECM tree establishment. We suggest that the ability of Salix to form dual AM and ECM associations allows it to become established across the open AM dominated vegetation. Over time these plants become colonised by ECM fungi via aerial spores and then can act as a source of inoculum for obligate ECM tree seedlings, which arrive as seeds in the vicinity of Salix. This study highlights the potential role of dual‐mycorrhizal Salix as a nurse plant in supporting secondary forest succession of obligate ECM boreal/temperate woodland species onto adjacent open areas through nucleation. Overall, we concluded that there is potential for existing ECM networks to aid tree establishment and propose a nature‐based approach to maximize reforestation efforts by targeting existing symbiotic fungal networks as nucleation points for tree planting. Our findings contribute to understanding the ecological dynamics involved in woodland expansion and restoration. [ABSTRACT FROM AUTHOR]

ABSTRACT Temperate grassy woodlands were once widespread in southeast Australia and were shaped by fire regimes imposed by Indigenous peoples. Today, they persist as scattered fragments in matrices of highly modified farmland, where fire is rare and eucalypt trees are in decline. Returning fire to these fragments is a suggested approach to reduce fuels and stimulate eucalypt recruitment. We implemented a single round of small, low‐intensity surface fires in a woodland fragment in the Tasmanian Midlands and assessed adult eucalypt mortality and juvenile recruitment. The fires were set during mild fire weather, were tended by 4–15 people, and fire‐fighting vehicles were used to extinguish burning trees. Still, the fires killed 7% of adult eucalypts (18 trees), mostly due to cambial girdling which occurred where burning litter and coarse woody debris at the base of the trees initiated smouldering fires in thick bark on the lower trunks. Seedling recruitment was restricted to ash beds near trees with viable seed crops. Seedlings survived only if protected from mammalian herbivores. Herbivore protection also increased the growth of lignotuberous sprouts after fire. Our findings demonstrate that eucalypt trees in degraded woodland fragments may be vulnerable to low‐intensity surface fire. We make recommendations as to how managers may burn woodland fragments in ways that avoid killing eucalypt trees and enhance postfire recruitment, enabling transition to more sustainable fire regimes. [ABSTRACT FROM AUTHOR]

Biogeographic context, such as biome type, has a critical influence on ecological resilience, as climatic and environmental conditions impact how communities respond to anthropogenic threats. For example, land‐use change causes a greater loss of biodiversity in tropical biomes compared to temperate biomes. Furthermore, the nature of threats impacting ecosystems varies geographically. Therefore, monitoring the state of biodiversity at a high spatial resolution is crucial to capture variation in threat–responses caused by biogeographical context. However such fine‐scale ecological data collection could be prohibitively resource intensive. In this study, we aim to find the spatial scale that could best capture variation in community‐level threat responses whilst keeping data collection requirements feasible. Using a database of biodiversity records with extensive global coverage, we modelled species richness and total abundance (the responses) across land‐use types (reflecting threats), considering three different spatial scales: biomes, biogeographical realms, and regional biomes (the interaction between realm and biome). We then modelled data from three highly sampled biomes to ask how responses to threat differ between regional biomes and taxonomic group. We found strong support for regional biomes in explaining variation in species richness and total abundance compared to biomes or realms alone. Our biome case studies demonstrate that there is variation in magnitude and direction of threat responses across both regional biomes and taxonomic group, although the interpretation is limited by sampling bias in the literature. All groups in tropical forest showed a consistently negative response, whilst many taxon‐regional biome groups showed no clear response to threat in temperate forest and tropical grassland. Our results provide the first empirical evidence that the taxon‐regional biome unit has potential as a reasonable spatial unit for monitoring how ecological communities respond to threats and designing effective conservation interventions to bend the curve on biodiversity loss. [ABSTRACT FROM AUTHOR]

Background: Deadwood decomposition is an essential ecological process in forest ecosystems, playing a key role in nutrient cycling and carbon sequestration by enriching soils with organic matter. This process is driven by diverse microbial communities encompassing specialized functions in breaking down organic matter, but the specific roles of individual microorganisms in this process are still not fully understood. Results: Here, we characterized the deadwood microbiome in a natural mixed temperate forest in Central Europe using PacBio HiFi long-read sequencing and a genome-resolved transcriptomics approach in order to uncover key microbial contributors to wood decomposition. We obtained high quality assemblies, which allowed attribution of complex microbial functions such as nitrogen fixation to individual microbial taxa and enabled the recovery of metagenome-assembled genomes (MAGs) from both abundant and rare deadwood bacteria. We successfully assembled 69 MAGs (including 14 high-quality and 7 single-contig genomes) from 4 samples, representing most of the abundant bacterial phyla in deadwood. The MAGs exhibited a rich diversity of carbohydrate-active enzymes (CAZymes), with Myxococcota encoding the highest number of CAZymes and the full complement of enzymes required for cellulose decomposition. For the first time we observed active nitrogen fixation by Steroidobacteraceae, as well as hemicellulose degradation and chitin recycling by Patescibacteria. Furthermore, PacBio HiFi sequencing identified over 1000 biosynthetic gene clusters, highlighting a vast potential for secondary metabolite production in deadwood, particularly in Pseudomonadota and Myxococcota. Conclusions: PacBio HiFi long-read sequencing offers comprehensive insights into deadwood decomposition processes by advancing the identification of functional features involving multiple genes. It represents a robust tool for unraveling novel microbial genomes in complex ecosystems and allows the identification of key microorganisms contributing to deadwood decomposition. [ABSTRACT FROM AUTHOR]

Large herbivorous mammals strongly influence vegetation structure by creating and maintaining open areas and causing disturbance within closed woody habitats. The herbivores alive today in Europe are only a small remnant of the large species that existed in high diversity and abundance before modern humans. The extinction of so many large herbivores during the last 50,000 years, and the loss of megaherbivores (body weight ≥1000 kg) from most of the continent before the Pleistocene–Holocene transition, is likely to have had cascading effects on vegetation structure and composition.To evaluate these effects within the European temperate forest biome, we examine the abundance change of three important European woody taxa (deciduous oaks, Quercus spp.; hazel, Corylus [mainly C. avellana]; and yew, Taxus baccata) before and after the late‐Quaternary downgrading of the region's large herbivore fauna. These taxa are disturbance‐favoured, depend on canopy openings for regeneration, and tend to decline in closed dense forests. Quercus and Corylus may thrive in systems affected by megafauna herbivory or fire, whilst Taxus is fire‐sensitive but can thrive in grazed systems. Using pollen‐based reconstructions (REVEALS), we investigated the proportional cover of these three focal taxa in the Last Interglacial (129,000–116,000 before present [BP]) and early–mid‐Holocene (8700–5700 BP).We found that woodlands in the Last Interglacial exhibited higher cover of Corylus and Taxus relative to the Holocene, with the former reaching very high percentage cover; meanwhile, Quercus had a consistent, moderately high percentage cover in both periods. Furthermore, we found that the cover of Corylus and Taxus appeared to be influenced more by unmeasured, non‐climatic factors than Quercus.Synthesis: The abundance of Taxus suggests a limited role of fire; whilst the observed levels of Taxus, Corylus and Quercus align with the potential influence of megafauna herbivory; however, a direct quantitative link remains to be established. Our results suggest that vegetation was structurally and compositionally affected by differences in disturbance regimes between the Last Interglacial and early–mid‐Holocene, with the loss of diverse disturbance regimes likely contributing to the divergence of Holocene vegetation from long‐term ecological baselines. [ABSTRACT FROM AUTHOR]

Tree microhabitats have been identified as structure-based indicators of biodiversity in temperate forests. However, information on diversity and abundance of these structures are minimal from the tropical regions. To address this, an inventory was conducted to document the distribution pattern of tree microhabitats in the Western Ghats, India. Tree microhabitats belonging to nine categories and 33 sub-categories in the evergreen and moist deciduous habitats were documented and horizontal and vertical distribution patterns were assessed. The evergreen habitat exhibited higher occurrences, with the abundance of injuries at 16.64 ± 6.31 per ha, epiphytes 20.48 ± 12.02 per ha, fungal fruiting bodies 2.68 ± 1.84 per ha, crown deadwood 5.12 ± 2.82 per ha, cavities 6.59 ± 1.37 per ha, growth forms 20.65 ± 3.96 per ha, deadwood 5.94 ± 1.97 per ha, and fresh exudates 0.99 ± 0.46 per ha. In deciduous forests, the abundance of injuries was 10.55 ± 2.95 per ha, epiphytes 6.88 ± 2.01 per ha, fungal fruiting bodies 2.75 ± 1.59 per ha, crown deadwood 6.58 ± 2.79 per ha, cavities 4.2 ± 1.51 per ha, growth forms 6.51 ± 2.19 per ha, deadwood 4.29 ± 1.52 per ha and fresh exudates 0.86 ± 0.96 per ha. Co-occurrence of tree cavities with other tree microhabitats were also presented. Injuries, growth forms, fungal fruiting bodies and deadwood were observed to have strongly correlated with the formation of cavities. [ABSTRACT FROM AUTHOR]

Habitat loss and fragmentation significantly affect avian breeding success. East-central Argentina's few native forests have become increasingly degraded by humans over time. Understanding the relationship between forest health and nesting success is critical since this information will be valuable as a point of comparison with future research if management actions are not taken. The study had two objectives: 1) describe the nesting biology of the Small-billed Elaenia (Elaenia parvirostris) and 2) assess whether a set of habitat features and time-specific variables had an effect on nest survival. We monitored 99 nests during three breeding seasons (2015–2018). Of all nests, 39% were successful, with predation causing the majority of nest failures (59%). We did not find important effects of habitat features on daily nest survival rate (DNSR). There was a cubic effect of nest age on the DNSR. Estimates of the cumulative probability to survive the entire nesting cycle was 41.2% (55.5% for egg laying, 16.1% for incubation, and 52% for nestling period). Our results add to the scientific understanding of life history strategies for south temperate birds while highlighting the need for additional research on native forest disturbances. [ABSTRACT FROM AUTHOR]

• An automatic burned area mapping algorithm based on active fire data and Sentinel-2 Level 2A imagery is presented. • Good concordance of the proposed algorithm with reference sources. • Global commission errors are higher than omission errors. • Forest fires in tropical and temperate forest are the least accurately mapped ecosystems. • Greater accuracy of the proposed algorithm in comparison to FIRECCI51 and MCD64A1. Understanding the spatial and temporal trends of burned areas (BA) on a global scale offers a comprehensive view of the underlying mechanisms driving fire incidence and its influence on ecosystems and vegetation recovery patterns over extended periods. Such insights are invaluable for modeling fire emissions and the formulation of strategies for post-fire rehabilitation planning. Previous research has provided strong evidence that current global BA products derived from coarse spatial resolution data underestimates global burned areas. Consequently, there is a pressing need for global high-resolution BA products. Here, we present an automatic global burned area mapping algorithm (Sentinel2BAM) based on Sentinel-2 Level-2A imagery combined with Visible Infrared Imaging Radiometer Suite (VIIRS) and Moderate Resolution Imaging Spectrometer (MODIS) active fire data. The algorithm employs a Random Forest Model trained by active fires to predict BA probabilities in each 5-day Normalized Burn Ratio (NBR) index-based temporal composites. In a second step, a time-series and object-based analysis of the estimated BA probabilities allows burned areas to be detected on a quarterly basis. The algorithm was implemented in Google Earth Engine (GEE) and applied to 576 Sentinel-2 tiles corresponding to 2019, distributed globally, to assess its ability to map burned areas across different ecosystems. Two validation sources were employed: 21 EMSR Copernicus Emergency Service perimeters obtained using high spatial resolution (<10 m) data (EMSR21) located in the Mediterranean basin and 50 20x20 km global samples selected by stratified sampling with Sentinel-2 at 10 m spatial resolution (GlobalS50). Additionally, 105 Landsat-based long sample units (GlobalL105), were employed to compare the performance of the Sentinel2BAM algorithm against the FIRECCI51 and MCD64A1 global products. Overall accuracy metrics for the Sentinel2BAM algorithm, derived from validation sources highlight higher commission (CE) than omission (OE) errors (CE=10.3 % and OE=7.6 % when using EMSR21 as reference, CE=18.9 % and OE=9.5 % when using Global S50 as reference), while GlobalL105-based inferenced global comparison metrics show similar patterns (CE=22.5 % and OE=13.4 %). Results indicate differences across ecosystems: forest fires in tropical and temperate biomes exhibit higher CE, mainly due to confusion between burned areas and croplands. According to GlobalL105, Sentinel2BAM shows greater accuracy globally (CE=22.5 %, OE=13.4 %) compared to FIRECCI51 (CE=20.8 %, OE=46.5 %) and MCD64A1 (CE=17.5 %, OE=53.1 %), substantially improving the detection of small fires and thereby reducing omission errors. The strengths and weaknesses of the algorithm are thoroughly addressed, demonstrating its potential for global application. [ABSTRACT FROM AUTHOR]

The Anthropocene concept raises awareness of human-induced planetary changes but is criticized for being 'too global'. We examined the social–ecological memory that emerges from people-tree relationships in South American temperate territories, Chile. We integrated dendrochronology (analysis of tree rings of 35 memorial trees; 17 species) with dendrography (participant observation complemented with semi-structured and go-along interviews with 14 interviewees; six women, eight men). We found that assemblages of people–tree relationships reflect marked historical changes in the territory, associated with the historical clearing of forests, which may be imprinted in both tree growth rings and in the social meanings and practices associated with memorial trees. In devastated territories, practices of tree care emphasize interconnectedness, multispecies collaborations, and the blurring of boundaries between humans and other-than-humans. We discuss some of the interdisciplinary and relational insights of our study, which may prove valuable for future research, political agendas, and educational programs in South America and beyond. [ABSTRACT FROM AUTHOR]

Aim: To quantify the intra‐community variability of leaf‐out (ICVLo) among dominant trees in temperate deciduous forests, assess its links with specific and phylogenetic diversity, identify its environmental drivers and deduce its ecological consequences with regard to radiation received and exposure to late frost. Location: Eastern North America (ENA) and Europe (EUR). Time Period: 2009–2022. Major Taxa Studied: Temperate deciduous forest trees. Methods: We developed an approach to quantify ICVLo through the analysis of RGB images taken from phenological cameras. We related ICVLo to species richness, phylogenetic diversity and environmental conditions. We quantified the intra‐community variability of the amount of radiation received and of exposure to late frost. Results: Leaf‐out occurred over a longer time interval in ENA than in EUR. The sensitivity of leaf‐out to temperature was identical in both regions (−3.4 days per °C). The distributions of ICVLo were similar in EUR and ENA forests, despite the latter being more species‐rich and phylogenetically diverse. In both regions, cooler conditions and an earlier occurrence of leaf‐out resulted in higher ICVLo. ICVLo resulted in ca. 8% difference of radiation received from leaf‐out to September among individual trees. Forest communities in ENA had shorter safety margins as regards the exposure to late frosts, and were actually more frequently exposed to late frosts. Main Conclusions: We conducted the first intercontinental analysis of the variability of leaf‐out at the scale of tree communities. North American and European forests showed similar ICVLo, in spite of their differences in terms of species richness and phylogenetic diversity, highlighting the relevance of environmental controls on ICVLo. We quantified two ecological implications of ICVLo (difference in terms of radiation received and exposure to late frost), which should be explored in the context of ongoing climate change, which affects trees differently according to their phenological niche. [ABSTRACT FROM AUTHOR]

Summary: Soil moisture shapes ecological patterns and processes, but it is difficult to continuously measure soil moisture variability across the landscape. To overcome these limitations, soil moisture is often bioindicated using community‐weighted means of the Ellenberg indicator values of vascular plant species. However, the ecology and distribution of plant species reflect soil water supply as well as atmospheric water demand. Therefore, we hypothesized that Ellenberg moisture values can also reflect atmospheric water demand expressed as a vapour pressure deficit (VPD).To test this hypothesis, we disentangled the relationships among soil water content, atmospheric vapour pressure deficit, and Ellenberg moisture values in the understory plant communities of temperate broadleaved forests in central Europe.Ellenberg moisture values reflected atmospheric VPD rather than soil water content consistently across local, landscape, and regional spatial scales, regardless of vegetation plot size, depth as well as method of soil moisture measurement.Using in situ microclimate measurements, we discovered that forest plant indicator values for moisture reflect an atmospheric VPD rather than soil water content. Many ecological patterns and processes correlated with Ellenberg moisture values and previously attributed to soil water supply are thus more likely driven by atmospheric water demand. [ABSTRACT FROM AUTHOR]

Summary: Co‐occurring plants show wide variation in their hydraulic and photosynthetic traits. Here, we extended 'least‐cost' optimality theory to derive predictions for how variation in key hydraulic traits potentially affects the cost of acquiring and using water in photosynthesis and how this, in turn, should drive variation in photosynthetic traits.We tested these ideas across 18 woody species at a temperate woodland in eastern Australia, focusing on hydraulic traits representing different aspects of plant water balance, that is storage (sapwood capacitance, CS), demand vs supply (branch leaf : sapwood area ratio, AL : AS and leaf : sapwood mass ratio and ML : MS), access to soil water (proxied by predawn leaf water potential, ΨPD) and physical strength (sapwood density, WD).Species with higher AL : AS had higher ratio of leaf‐internal to ambient CO2 concentration during photosynthesis (ci : ca), a trait central to the least‐cost theory framework. CS and the daily operating range of tissue water potential (∆Ψ) had an interactive effect on ci : ca. CS, WD and ΨPD were significantly correlated with each other. These results, along with those from multivariate analyses, underscored the pivotal role leaf : sapwood allocation (AL : AS), and water storage (CS) play in coordination between plant hydraulic and photosynthetic systems.This study uniquely explored the role of hydraulic traits in predicting species‐specific photosynthetic variation based on optimality theory and highlights important mechanistic links within the plant carbon–water balance. See also the Commentary on this article by Macinnis‐Ng, 244: 1681–1683. [ABSTRACT FROM AUTHOR]

Scavenging of small avian corpses may provide ants with a valuable source of nutrients, a possibility poorly studied.Here, we assessed whether ants are efficient carrion‐decomposers of avian corpses in Mediterranean dehesas through an exclusion experiment comparing decomposition rates among three treatments: vertebrate exclusion, vertebrate + invertebrate exclusion and control. Treatments were applied in a paired design in bird cavities and on the ground in two zones to assess functional redundancy. Ant community was characterized by pitfall traps, and key functional traits influencing ants' presence on carrion were identified by using phylogenetic comparative methods.Carrion decomposition was influenced by the exclusion treatment, being significantly faster when ants and other invertebrates were not excluded, but not by location (cavity/ground). Vertebrates were less likely to detect baits in cavities and removed more bait mass in the most transformed zone. Twelve of 25 ant species in the community were found foraging on baits. Ant communities differed between carrion location and localities. Phylogenetic analyses revealed that the proneness of ant species to forage on carrion was unrelated to morphological or social traits, but behavioural, being higher among species foraging collectively.Our results show that ants play a functionally unique role in the decomposition of small corpses in dehesas, and particularly so in trees and less transformed pastureland. Decomposition involves different species in different microhabitats, suggesting high functional redundancy across ants. Our findings provide new insights into the role of ants as scavengers and expand our understanding of the functioning of Mediterranean communities. [ABSTRACT FROM AUTHOR]

In forests, the distribution of vascular epiphytes is controlled by various environmental factors such as host tree size and substrate type. However, a few studies focused on temperate forests, despite the growing interest in temperate forests with high diversity of accidental epiphytes. This study examined the distribution of accidental and obligate epiphytes on 8 Cercidiphyllum japonicum (Cercidiphyllaceae) trees in a Japanese temperate forest based on observations of 1,301 epiphyte individuals belonging to 49 species. As predicted, the number of species and individuals of accidental and obligate epiphytes increased with host tree size. While the percentage of accidental epiphyte species increased with the host tree size, the percentage of obligate epiphyte species decreased; however, these changes were not significant for the number of individuals. Consistent with our hypothesis, the major rooting substrates of accidental and obligate epiphytes was different. Accidental epiphytes primarily depend on arboreal soil and, to a lesser extent, on moss, but are absent on tree bark. Contrastingly, obligate epiphytes were most frequently found on moss, followed by bark and arboreal soil. These results highlight the impact of host tree size on the diversity of accidental epiphytes compared to obligate epiphytes, suggesting that the host tree size effects are different between accidental and obligate epiphytes in temperate forests. Additionally, a thick accumulation of arboreal soil is crucial for the establishment of accidental epiphytes. [ABSTRACT FROM AUTHOR]

The dispersal process in plants links adults and their offspring. Mistletoes are shrubby stem-parasitic plants for which seed dispersal is a critical link in their life cycle. The mistletoe Tristerix corymbosus has a wide latitudinal distribution spanning two different biomes: the Chilean Matorral in the north, and the Temperate Forest of South America in the south. The assemblage of seed dispersers is different in these biomes. Tristerix corymbosus is dispersed by three bird species in the Chilean Matorral, but in the Temperate Forest it is dispersed only by arboreal marsupials of the genus Dromiciops. We aimed to assess the effectiveness of T. corymbosus seed dispersal by these disperser groups in terms of deposition of seeds in suitable sites (host plant species and branch size) and the effect of seed passage through the digestive tract. For this, we selected 22 localities throughout the distributional range of T. corymbosus, 8 in the Chilean Matorral and 14 in the Temperate Forest. In each locality, we recorded the cover percentage of different substrates (host plants, non-host plants, and bare soil) and the patterns of deposition of faeces. Also, we conducted seed germination trials using control seeds, hand-cleaned seeds, and seeds defecated by each disperser group. We found that both groups of animals are efficient dispersers of T. corymbosus seeds within each biome, because they deposit seeds in suitable sites and improve seed germination. However, the spatial segregation and the different behavior displayed by these groups may be contributing to a gradual process of genetic differentiation between mistletoes inhabiting these two biomes. [ABSTRACT FROM AUTHOR]

Fallen deadwood is essential for biodiversity and nutrient cycling in forest ecosystems. In modern forest management, there is growing interest in developing accurate and efficient methods for field estimation of deadwood volume due to its many benefits (e.g. carbon storage, habitat creation, erosion control). The most common methods for deadwood inventories are fixed-area sampling (FAS) and line-intersect sampling (LIS) methods. While the estimations of deadwood volume by LIS generally show results comparable to FAS estimations, active management (e.g. production forestry clearcutting, logging, and thinning activities) can impair LIS accuracy by changing local deadwood patterns. Yet, the comparison of LIS and FAS methods has typically focused on production forests where deadwood is limited and deadwood volumes are comparably low. In this study, we assessed fallen deadwood volume in two large national parks—one being a more actively managed landscape (including, e.g. selective thinning for maintaining cultural–historical values and enhancing recreational opportunities) with overall lower levels of fallen deadwood, and the other having a strict non-intervention approach with higher levels of deadwood. No significant differences between average FAS and LIS estimations of deadwood volumes were detected. Additional experimentations using simulated data under varied stand conditions confirmed these results. Although line-intersect sampling showed a slight overestimation and some variability at the individual plot level, it remains an efficient, time-saving field sampling method providing comparable results to the more laborious fixed-area sampling. Line-intersect sampling may be especially suitable for rapid field inventories where relative changes in deadwood volume rather than absolute deadwood volumes are of large interest. Due to its practicality, flexibility, and relative accuracy, line-intersect sampling may gain wider use in natural resource management to inform national park managers, foresters, and ecologists. [ABSTRACT FROM AUTHOR]

Biomass from surplus forest growth that is not harvested for wood supply of conventional industries can be an important source of feedstock for bioenergy. Its procurement can be integrated with little effort into current harvest operations. However, the increasing harvesting intensity to meet greater demand for biomass procurement can impact forest ecosystem functions because of its direct and indirect effects on woody debris and the regeneration of next-rotation stands. In this context, we aimed to determine the relationships between wood procurement intensity, woody debris inputs, and regeneration success over 2 years after harvesting. We tested four treatments of increasing wood procurement intensity using a randomized block design within six experimental sites along a gradient of varying forest characteristics of boreal and temperate forests. We assessed stand characteristics in terms of standing trees, woody debris, and regeneration pre- and post-harvest. We used mixed effects models to evaluate (i) the effects of wood procurement intensity and pre-harvest stand characteristics on the volume and cover of woody debris and (ii) the specific influence of woody debris on the presence of suitable planting microsites post-harvest. Furthermore, we used principal component regressions to explore the relationships between harvesting intensity and the presence of natural regeneration and competing vegetation as a function of pre- and post-harvest stand characteristics (iii). Our results showed that increasing wood procurement intensity reduced the volume of post-harvest woody debris while having a limited effect on regeneration. Increasing harvesting intensity had a negligible effect on suitable planting microsites in hardwood-dominated stands but it increased their presence in conifer-dominated stands. Natural regeneration and competing vegetation were mainly related to stand characteristics, and only broadleaf regeneration was sensitive to harvest intensity. We conclude that the relationships between wood procurement intensity and regeneration are complex and rely mainly on stand characteristics rather than wood procurement needs. [ABSTRACT FROM AUTHOR]

Hedera helix L. is a widespread liana that significantly influences forest ecosystems in temperate zones, exhibiting high adaptability to varying soil moisture and light levels. In this study, it was confirmed that H. helix dominates the herbaceous layer of the Kórnik Arboretum (Poland), with clear links between its above-ground biomass and key environmental factors. The study revealed that, under intense soil shading, the leaf to stem biomass ratio was disproportional, favoring leaves. Leaf and stem water content reflected the plant's adaptation to soil moisture, aligning with its field capacity. Strong relationships were found between leaf water content and soil moisture, while the correlations between leaf water content and light availability were weaker. The study also confirmed positive relationships between daily light integral and leaf water content, with a less pronounced effect on stem water content. These results enhance understanding of H. helix 's role in temperate forests and its impact on ecosystem regeneration. [ABSTRACT FROM AUTHOR]

Detailed three-dimensional (3D) radiative transfer models (RTMs) enable a clear understanding of the interactions between light, biochemistry, and canopy structure, but they are rarely explicitly evaluated due to the availability of 3D canopy structure data, leading to a lack of knowledge on how canopy structure/leaf characteristics affect radiative transfer processes within forest ecosystems. In this study, the newly released 3D RTM Eradiate was extensively evaluated based on both virtual scenes reconstructed using the quantitative structure model (QSM) by adding leaves to point clouds generated from terrestrial laser scanning (TLS) data, and real scenes monitored by Sentinel-2 in a typical temperate deciduous forest. The effects of structural parameters on reflectance were investigated through sensitivity analysis, and the performance of the 3D model was compared with the 5-Scale and PROSAIL radiative transfer models. The results showed that the Eradiate-simulated reflectance achieved good agreement with the Sentinel-2 reflectance, especially in the visible and near-infrared spectral regions. Furthermore, the simulated reflectance, particularly in the blue and shortwave infrared spectral bands, was clearly shown to be influenced by canopy structure using the Eradiate model. This study demonstrated that the Eradiate RTM, based on the 3D explicit representation, is capable of providing accurate radiative transfer simulations in the temperate deciduous forest and hence provides a basis for understanding tree interactions and their effects on ecosystem structure and functions. [ABSTRACT FROM AUTHOR]

Forest management is an important component of global change as more than half of the world's forests are managed for human use. Although the effect of forest management on taxonomic diversity is well‐studied, we do not fully understand its impact on functional diversity. Understanding this is important to better predict how ecosystem processes will respond to global change scenarios and to implement efficient conservation actions. We conducted two large‐scale (~81 800 km2) research projects over 4 years in temperate forests of the northeastern USA to investigate how the functional structure of bird and mammal communities are affected by forest disturbance. We surveyed 85 bird species distributed in 115 sites using point counts, and 14 mammal species across 197 sites using camera traps. For each species, we selected functional traits that summarize key features of their biology, and for each site, we collected data on the level of forest disturbance based on forest loss events. We found that functional richness increased with forest disturbance for mammals but not for birds. Our results also showed that niche breadth (diet), morphological (body mass and wing length), and physiological (litter size) factors were the main determinants of the functional structure of both groups. These findings emphasize the complexity of making predictions about responses to forest management given the heavy dependence on the context and taxa studied. Overall we observed a limited response of functional diversity to forest management, which might indicate that the environmental changes generated by forest management in this region are less extreme than deforestation or conversion of natural forest to plantations of exotic species. Nonetheless, our results underscore the importance of investigating the effects of forestry on individual traits to develop strategies for managing for ecosystem functions. [ABSTRACT FROM AUTHOR]

Lidar sensors are active remote sensing instruments that provide data on forest structure, which serve as inputs in the prediction of forest parameters. The objective of this study was to evaluate the performance of mixed-effects models to predict basal area (BA), aboveground biomass (AGB), and wood volume (VOL) from GEDI (Global Ecosystem Dynamics Investigation) predictor variables. Linear mixed and generalized linear mixed models (LMM and GLMM) were fitted with a clustering structure as a random effect between forest parameters and GEDI metrics. LMM and GLMM performed similarly regarding root mean square error (RMSE) and correlation coefficients (r) between observed and predicted data. Our results showed moderate correlations between RH50 and BA (r = 0.53), AGB (r = 0.54), and RH80 with VOL (r = 0.62). Another finding was the correlation between GEDI predictions of the AGB density and the biomass predicted in this study, with an agreement of 79% and 77% and a RMSE of 76.95 and 82.34 Mg ha−1 for LMM and GLMM, respectively. We conclude that the use of mixed models allowed for the inclusion of both fixed and random effects that capture the systematic and random variation in the data, and they provide a flexible framework for modelling forest parameters. [ABSTRACT FROM AUTHOR]

Premise Methods Results Conclusions The soils in lowland tropics are teeming with microbial life, which can impact plant community structure and diversity through plant–soil feedbacks. While bacteria and fungi have been the focus of most studies in the tropics, oomycetes may have an outsized effect on seed and seedling health and survival, given their affinity for moister, warmer environments.We assessed the diversity and pathogenicity of oomycete species present in a lowland tropical forest in Panama. We used a culture‐dependent leaf‐baiting assay and culture‐independent soil DNA metabarcoding methods to quantify zoospore abundance and species diversity. A subset of the isolates from the baiting assay were used to evaluate pathogenicity and symptom severity on seedlings of three tree species.Oomycetes were ubiquitous and common members of the soil microbial community in lowland tropical forests, and zoospore abundance was far greater compared to similar studies from temperate and mediterranean forests. The various oomycete species also varied in the ability to infect host plants. Species of Pythium were more virulent, while species of Phytopythium caused less severe symptoms but were more diverse and commonly isolated from the soil. Finally, we found that individual hosts accumulated a distinct oomycete community and was the only factor that had an effect on community structure.Collectively, these findings demonstrate that oomycetes are ubiquitous, host‐generalist pathogens and saprophytes, that can impact seed and seedling survival in lowland tropical forests. [ABSTRACT FROM AUTHOR]

Leaf-associated fungi, the fungi that depend on leaves to sporulate, have a rich Cenozoic record, however their earlier diversity is poorly characterized. Here we describe Harristroma eboracense gen. et sp. nov., a Middle Jurassic leaf-associated fungus colonizing the leaf cuticle of Nilssonia tenuicaulis (cycadophyte). To place our newly described species into a picture of the diversification of Mesozoic fungi, we reassess fossils with leaf-associated stromata in the context of fungal molecular phylogeny. Being melanized, with radiate stromata, and on leaves, H. eboracense and other fossils from the Jurassic and earlier periods are probably related to filamentous Ascomycota in the superclass Leotiomyceta. Characters needed for further resolution of leaf-associated fungal biology and classification, such as the presence of an ostiole for spore discharge and appressoria for entry into leaf tissue first appear in the Mesozoic fossil record. Among Early Cretaceous fossils, Spataporthe taylorii represents the oldest unambiguous evidence of perithecial Sordariomycetes while Protographum luttrellii and Bleximothyrium ostiolatum are the oldest Dothideomycetes thyriothecia. Environmental observations show that broad leaved gymnosperms (especially cycadophytes) growing in warm temperate wet forests might have been the first environment for the radiation of Leotiomyceta. [ABSTRACT FROM AUTHOR]

Plant species richness and composition are influenced by complex interactions between biotic and abiotic factors that operate on different spatial scales. Since spatial scales vary continuously in nature, it is expected that multiple factors simultaneously affect species richness and composition at an intermediate spatial scale (i.e., the mesoscale landscape level). Previous studies have shown that local topography and elevation are important factors for shaping intermediate spatial scale plant species richness; however, the relative importance of these factors has rarely been examined. Here, we used spatially explicit woody plant data to examine the factors that characterize the spatial pattern of primary evergreen forest biodiversity at the intermediate spatial scale. We found that the spatial pattern of species diversity in a predominantly warm temperate evergreen forest at the landscape level is mainly characterized by shifts in species composition along the elevation gradient. Our study also found that compositional shift along the elevational gradient was mainly caused by habitat specialization among congeneric species, suggesting that niche partitioning among closely-related species is a fundamentally important feature of the intermediate spatial scale species richness pattern. Furthermore, we found that specialization in a habitat of closely-related species can be established even within a limited environmental gradient. This suggests that biotic interactions among closely-related species may be an important factor driving habitat specialization, and biotic interactions may play an important role in shaping landscape-scale biodiversity patterns. [ABSTRACT FROM AUTHOR]

Accurate mapping of above-ground biomass (AGB) is essential for carbon stock quantification and climate change impact assessment, particularly in mountainous areas. This study applies a random forest (RF) regression model to predict the spatial distribution of AGB in Usho (site A) and Utror (site B) forests located in the northern mountainous region of Pakistan. The predicted maps elucidate AGB variations across these sites, with non-forest areas excluded based on an normalized difference vegetation index (NDVI) threshold value of <0.4. Three different combinations of input datasets were used to predict the biomass, including spectral bands (SBs) only, vegetation indexes (VIs) only, and a combination of both spectral bands and vegetation indexes (SBVIs). Utilizing SBs, the biomass ranged between 150 and 286 mg/ha in site A and 99 and 376 mg/ha in site B. Meanwhile, using VIs indicated a biomass range of 163 Mg/ha–337 Mg/ha and 131–392 Mg/ha for sites A and B, respectively. The combination of spectral bands and vegetation indexes yielded AGB values of 145–290 Mg/ha in site A and 116–389 Mg/ha in site B. The northern and western regions of site A, characterized by higher altitudes and lower forest density, notably showed lower biomass values than other regions. Conversely, similar regions in site B, situated at lower latitudes, demonstrated different biomass ranges. The RF model exhibited robust accuracy, with R2 values of 0.74 and 0.83 for spectral bands and vegetation indexes, respectively. However, with a combination of both, an R2 of 0.79 was achieved. Furthermore, altitudinal gradients significantly influence the biomass distribution across both sites, with specific elevation ranges yielding optimal results. The AGB variation along the slope further corroborated these findings. In both sites, the western aspects showed the highest biomass across all combinations of input datasets. The variable importance analysis highlighted that ARVI8a, NDI45, Band12, Band11, TSAVI8, and ARVI8a are significant predictors in sites A and B. This comprehensive analysis enhances our understanding of AGB distribution in the mountainous forests of Pakistan, offering valuable insights for forest management and ecological studies. [ABSTRACT FROM AUTHOR]

Despite deep learning being state of the art for data‐driven model predictions, its application in ecology is currently subject to two important constraints: (i) deep‐learning methods are powerful in data‐rich regimes, but in ecology data are typically sparse; and (ii) deep‐learning models are black‐box methods and inferring the processes they represent are non‐trivial to elicit. Process‐based (= mechanistic) models are not constrained by data sparsity or unclear processes and are thus important for building up our ecological knowledge and transfer to applications. In this work, we combine process‐based models and neural networks into process‐informed neural networks (PINNs), which incorporate the process knowledge directly into the neural network structure. In a systematic evaluation of spatial and temporal prediction tasks for C‐fluxes in temperate forests, we show the ability of five different types of PINNs (i) to outperform process‐based models and neural networks, especially in data‐sparse regimes with high‐transfer task and (ii) to inform on mis‐ or undetected processes. [ABSTRACT FROM AUTHOR]

Tree cavities offer protected shelters and resources for arboreal vertebrates worldwide. In general, cavities with larger openings are better accessible for predators and are avoided by smaller species for breeding, but can still be attractive for occasional use. The current study explores the diversity of functional use types and species interactions at the largest available tree cavities (entrance width ≥ 10 cm) in a temperate European forest with a low number of large cavity‐breeding species. Year‐round camera observations at 9 cavities (range 0.7–3.5 years) revealed 34 visiting species of birds and mammals, including non‐cavity‐breeding species. The top predator threatening other large‐cavity users was European pine marten (Martes martes), which regularly visited each cavity year‐round, on average every 0.7 months. Tawny owl (Strix aluco) was the only species successfully breeding in cavities, arguably because of its ability to defend the nests. However, other species visited cavities at an average rate of 1.5 visits per day, making predominantly short visits (less than 30 s) interpreted as exploration, searching for food, or inspecting for the presence of owls (mobbing). Making short visits and time segregation with predators was a behavioural strategy to exploit cavities for most species. These results confirm that, similarly to other keystone structures (large arboreal nests, ground burrows, etc.), large tree cavities attract a significant part of the arboreal vertebrate community and enrich their habitats. To sustain these functions in wooded ecosystems, management should provide a surplus of available cavities and diversity of their characteristics even when the apparent number of breeding species is low. [ABSTRACT FROM AUTHOR]

Insect herbivory plays a crucial role in shaping plant communities in many terrestrial ecosystems. However, in African savannas, insect herbivory has been relatively understudied compared to large mammalian herbivory. In this study, we examined the impact of insect herbivory, focusing on leaf chewers and miners, in a South African savanna‐forest mosaic (including patches of forest, thicket and savanna) in Hluhluwe iMfolozi Park, South Africa. Our investigation spanned gradients of rainfall, fire frequency and mammal density. We surveyed a total of 864 woody plants from 48 plant species in 38 plots. Insects consumed 6% of leaf biomass, which is comparable to their impact in temperate broadleaf forests, but the extent of herbivory damage varied between vegetation types. Overall, leaf loss was 70% higher in forests and savanna than that in thicket. Plants in the forests experienced greater damage from chewing insects, whereas miners caused relatively more damage in savannas. Rates of insect herbivory also varied among plant species, declining with carbon and dry matter content but increasing with specific leaf area. Although no significant trade‐off was detected between insect and mammal herbivory, plant species with limited physical defences against mammals tended to experience high levels of insect herbivory. Our findings highlight the intricate dynamics of insect herbivory in different vegetation types and suggest that insect leaf herbivory, alongside mammalian herbivory, could play a significant role in influencing plant community composition and overall savanna ecosystem functioning. [ABSTRACT FROM AUTHOR]

'Water potential' is the biophysically relevant measure of water status in vegetation relating to stomatal, canopy and hydraulic conductance, as well as mortality thresholds; yet, this cannot be directly related to measured and modelled fluxes of water at plot‐ to landscape‐scale without understanding its relationship with 'water content'. The capacity for detecting vegetation water content via microwave remote sensing further increases the need to understand the link between water content and ecosystem function. In this review, we explore how the fundamental measures of water status, water potential and water content are linked at ecosystem‐scale drawing on the existing theory of pressure‐volume (PV) relationships. We define and evaluate the concept and limitations of applying PV relationships to ecosystems where the quantity of water can vary on short timescales with respect to plant water status, and over longer timescales and over larger areas due to structural changes in vegetation. As a proof of concept, plot‐scale aboveground vegetation PV curves were generated from equilibrium (e.g., predawn) water potentials and water content of the above ground biomass of nine plots, including tropical rainforest, savanna, temperate forest, and a long‐term Amazonian rainforest drought experiment. Initial findings suggest that the stored water and ecosystem capacitance scale linearly with biomass across diverse systems, while the relative values of ecosystem hydraulic capacitance and physiologically accessible water storage do not vary systematically with biomass. The bottom‐up scaling approach to ecosystem water relations identified the need to characterise the distribution of water potentials within a community and also revealed the relevance of community‐level plant tissue fractions to ecosystem water relations. We believe that this theory will be instrumental in linking our detailed understanding of biophysical processes at tissue‐scale to the scale at which land surface models operate and at which tower‐based, airborne and satellite remote sensing can provide information. [ABSTRACT FROM AUTHOR]

Simple Summary: Palearctic wood ants are territorial species that require a stable and productive environment for the construction of complex nests and the formation of large-sized colonies with high energy demand. Norway spruce is the preferred host tree species for wood ants; thus spruce mortality could have severe consequences for wood ant colonies, as well as their vitality and distribution. In this study, we investigated whether a bark beetle outbreak had an impact on the density and abundance of wood ant nests and whether we could find factors influencing the dead spruce distribution around ant nests. After a large-scale bark beetle outbreak in the Białowieża Forest, we did not observe any changes in the density of wood ant nests. The results show that the proportion of dead spruce around the nests decreased with an increase in the total proportion of spruce in the forest stand. Our results also suggest that despite the importance of spruce for wood ants, in situations where only a proportion of spruce die, natural forest disturbances such as bark beetle outbreaks can actually have positive effects, as more light can reach the forest floor, thereby promoting the establishment of new nests. In the Białowieża Forest, Norway spruce is the preferred host tree species for wood ants, both in coniferous and mixed stands; thus, spruce mortality as a consequence of a continuous spruce bark beetle outbreak in the Białowieża Forest since 2012 could have severe consequences for wood ant colonies, as well as their vitality and distribution. The main aim of this study was to assess whether the bark beetle outbreak had any effects on wood ant nest density and abundance and whether we could find any factors affecting the dead spruce distribution around ant nests. A re-inventory of active and abandoned wood ant nests in our study area was conducted from April to July 2022, using the same procedure as the previous inventory performed in 2016. The wood ant nest density was 0.11 per ha and remained practically the same relative to that determined in 2016. Our results indicate that, despite the importance of spruce for wood ants, in situations when only part of the spruce trees die, natural forest disturbances such as bark beetle outbreaks can actually have positive effects because more light can reach the forest floor, thereby promoting the establishment of new nests. [ABSTRACT FROM AUTHOR]

Although Tetracladium species have traditionally been studied as aquatic saprotrophs, the growing number of metagenomic and metabarcoding reports detecting them in soil environments raises important questions about their ecological adaptability and versatility. We investigated the factors associated with the relative abundance, diversity and ecological dynamics of Tetracladium in temperate forest soils. Through amplicon sequencing of soil samples collected from 54 stands in six forest sites across the eastern United States, we identified 29 distinct Amplicon Sequence Variants (ASVs) representing Tetracladium, with large differences in relative abundance and small changes in ASV community composition among sites. Tetracladium richness was positively related to soil pH, soil temperature, total sulphur and silt content, and negatively related to plant litter quality, such as the lignin‐to‐nitrogen ratio and the lignocellulose index. Co‐occurrence network analysis indicated negative relationships between Tetracladium and other abundant fungal groups, including ectomycorrhizal and arbuscular mycorrhizal fungi. Collectively, our findings highlight the ecological significance of Tetracladium in temperate forest soils and emphasize the importance of site‐specific factors and microbial interactions in shaping their distribution patterns and ecological dynamics. [ABSTRACT FROM AUTHOR]

Defining the seed dormancy profile (SDP) of plant communities may provide insight into species adaptive mechanisms, community structure, and dynamics. Golestan National Park (GNP) in Iran consists of different types of vegetation, namely deciduous temperate forest, matorral, and steppe in close proximity but with variability of environmental factors. Plant species, life forms, and kinds of seed dormancy were determined in the three vegetation types, and a SDP of types was generated and compared with corresponding ones in the world database. In all GNP vegetation types, 80%–82% and 2%–3% of the species had dormant (D), and nondormant (ND) seeds, respectively, but in 17% the class of dormancy was unknown. Physiological dormancy (PD) was the most abundant followed by physical dormancy (PY). The species percentage with ND seeds in GNP was significantly two or three times lower than that in the world database. The PD percentage in the matorral was significantly higher than that in the world database. The PY percentage was higher in the forests but lower in the matorral and steppe compared with the world database. The morphophysiological (MPD) dormancy percentage was significantly lower in the forests but higher in the matorral and steppe than in the global database. Seed dormancy profiles were not affected by the proximity of vegetation types in the GNP, but they differed from those of the world database for each vegetation type. The past climatic fluctuations associated with the present‐day seasonality of the region might be the selective pressure for the increased percentage of species with D seeds in the GNP. [ABSTRACT FROM AUTHOR]

Effective forest management necessitates spatially explicit information about tree species composition. This information supports the safeguarding of native species, sustainable timber harvesting practices, precise mapping of wildlife habitats, and identification of invasive species. Tree species identification and geo-location by machine learning classification of UAV aerial imagery offer an alternative to tedious ground surveys. However, the timing (season) of the aerial surveys, input variables considered for classification, and the model type affect the classification accuracy. This work evaluates how the seasons and input variables considered in the species classification model affect the accuracy of species classification in a temperate broadleaf and mixed forest. Among the considered models, a Random Forest (RF) classifier demonstrated the highest performance, attaining an overall accuracy of 83.98% and a kappa coefficient of 0.80. Simultaneously using input data from summer, winter, autumn, and spring seasons improved tree species classification accuracy by 14–18% from classifications made using only single-season input data. Models that included vegetation indices, image texture, and elevation data obtained the highest accuracy. These results strengthen the case for using multi-seasonal data for species classification in temperate broadleaf and mixed forests since seasonal differences in the characteristics of species (e.g., leaf color, canopy structure) improve the ability to discern species. [ABSTRACT FROM AUTHOR]

Despite the importance of fungi to forest carbon (C) cycling and increasing calls to include microbial interactions in ecosystem models, how shifting fungal guild abundances impact soil C stocks remains poorly quantified, particularly in mineral soils where most C is stored. Additionally, a greater understanding of how fungal interguild interactions affect belowground litter decomposition is needed to more fully characterize soil C dynamics. To address these knowledge gaps, we conducted a multi-year soil trenching experiment in two temperate Pinus strobus stands in Minnesota, USA. We found that after two years, trenching increased ectomycorrhizal fungal relative abundance while decreasing saprotrophic fungal relative abundance (decreased ectomycorrhizal/saprotrophic ratio) and concurrently decreased soil C stocks by 10%. The decreased C stocks were primarily due to changes in particulate organic matter and were largely constrained to the top 5 cm of the soil. Trenching also stimulated both root and fungal litter decomposition in surface soils. Together, these results support the often proposed but rarely tested hypothesis that shifting fungal guild abundances promote soil C accumulation. However, they also suggest this effect may be most relevant for short-term C storage in upper soil layers. [ABSTRACT FROM AUTHOR]

The importance of woody detritus as a source of soil organic matter is not well constrained. We quantified the recovery of 13C derived from isotopic-enriched sugar maple wood in various C fractions of two temperate forest soils in central New York, USA. Decay rates of small woody debris were quite rapid (k = 0.362 to 0.477 per year) and after 10 years less than 1% of the original wood mass remained in incubation bags. After six years we recovered only 0.26% (± 0.025) of the added 13C in the upper 5 cm of underlying soil. After 10 years this recovery declined to 0.11% (± 0.020) indicating substantial lability of retained SOC; most of this decline occurred from year 6 to 8 in the 1–5 cm depth increment, suggesting that the residue was quite stable at 10 years. The largest fraction of 13C was recovered in microaggregates (45%), especially those occluded within macroaggregates (30%), with a smaller proportion associated with the silt + clay fraction (20%). These proportions did not change significantly from year 6 to 10. Faster decay and higher 13C recovery were coincident with abundant saproxylic invertebrates from Scarabaeidae at one of the sites. We conclude that small woody debris is a minor source of stable SOC in these temperate forests (that is, less than 1% of annual SOC accumulation). [ABSTRACT FROM AUTHOR]

Earthworms are important ecosystem engineers that stabilize soil aggregates and increase the size of aggregates. The major determinants for the biomass, density, and mean individual weight of lumbricid earthworms are considered to be the availability of soil organic carbon (SOC) and calcium (Ca). However, the importance of SOC and Ca availability for lumbricid earthworms has not been tested simultaneously in the field. In addition, the ripple effects of SOC and Ca on the soil aggregate stability and relative abundance of larger aggregates (mean weight diameter; MWD) via earthworm communities are poorly understood. To fill these knowledge gaps, we conducted field research across a spatially wide range of cool temperate forests, where soils were classified as Cambisols and Andosols and evaluated the relationships among the biomass, density, and mean individual weight of lumbricid earthworms, soil chemical properties, and MWD by conducting structural equation modelling (SEM). Our results showed that SOC affected not the density but the mean individual weight of earthworms. On the other hand, interestingly, exchangeable Ca affected not the mean individual weight but the density of earthworms. These results suggest that SOC stimulates earthworm growth and that exchangeable. Ca enhances the fertility rate and/or survival rate in earthworm communities in forest ecosystems. Furthermore, SOC had a positive ripple effect on the MWD via an increase in the mean individual weight of earthworms. These results suggest that larger earthworms produce larger casts, which bind a larger amount of soil particles thus making larger aggregates. [ABSTRACT FROM AUTHOR]

Irruptive forest insects are a leading biotic disturbance across temperate and boreal forests. Outbreaks of forest insects are becoming more frequent and extensive due to anthropogenic drivers (e.g. climate and land‐use), perhaps increasing the likelihood that forests will experience multiple insect‐caused disturbances.Across the fire‐prone Douglas‐fir forests of western North America, recent outbreaks of the western spruce budworm and Douglas‐fir beetle have impacted large expanses of forests, with a higher degree of overlap than expected in some ecoregions. Outbreaks of both insects are positively related to host availability and exhibit density‐dependent population dynamics that are affected by climate and weather.Here, we leverage data from aerial detection surveys, estimates of host availability, climate and weather, and categorized fire severity to describe the spatial overlap between western spruce budworm and Douglas‐fir beetle and assess: (1) how climate and host availability influence the biogeography of outbreaks; (2) how weather incites outbreaks; and finally, (3) how prior disturbances (fire and biotic) affect the subsequent outbreak likelihood of western spruce budworm and Douglas‐fir beetle.Models demonstrate that western spruce budworm and Douglas‐fir beetle share similar predisposing drivers of outbreaks. Outbreaks of both insects were more likely to occur following warm weather, but only beetle outbreaks were more likely following drought. When controlling for differences in outbreak distribution and inciting factors, results indicate that both prior fire and interspecific disturbance altered the likelihood of subsequent insect‐caused disturbance.Specifically, Douglas‐fir beetle outbreaks were more likely to occur for several years following low severity fire, but less likely otherwise. Prior defoliation, especially longer duration defoliation, increased the likelihood of beetle outbreak within stands and across the landscape. On the contrary, western spruce budworm outbreaks were less likely to occur following fire, while prior beetle activity dampened budworm outbreak likelihood for several years, and then eventually increased outbreak likelihood.Synthesis: Biotic–biotic disturbance interactions have the potential to amplify the incidence of insect‐caused disturbance across subcontinental scales. Our findings highlight the need for future work on mechanistic linkages between biotic disturbance agents as well as the ramifications for forest trajectories and function. [ABSTRACT FROM AUTHOR]

Birds, bats and ants are recognised as significant arthropod predators. However, empirical studies reveal inconsistent trends in their relative roles in top‐down control across strata. Here, we describe the differences between forest strata in the separate effects of birds, bats and ants on arthropod densities and their cascading effects on plant damage.We implemented a factorial design to exclude vertebrates and ants in both the canopy and understorey. Additionally, we separately excluded birds and bats from the understorey using diurnal and nocturnal exclosures. At the end of the experiments, we collected all arthropods and assessed herbivory damage.Arthropods responded similarly to predator exclusion across forest strata, with a density increase of 81% on trees without vertebrates and 53% without both vertebrates and ants. Additionally, bird exclusion alone led to an 89% increase in arthropod density, while bat exclusion resulted in a 63% increase. Herbivory increased by 42% when vertebrates were excluded and by 35% when both vertebrates and ants were excluded. Bird exclusion alone increased herbivory damage by 28%, while the exclusion of bats showed a detectable but non‐significant increase (by 22%). In contrast, ant exclusion had no significant effect on arthropod density or herbivory damage across strata.Our results reveal that the effects of birds and bats on arthropod density and herbivory damage are similar between the forest canopy and understorey in this temperate forest. In addition, ants were not found to be significant predators in our system. Furthermore, birds, bats and ants appeared to exhibit antagonistic relationships in influencing arthropod density. These findings highlight, unprecedentedly, the equal importance of birds and bats in maintaining ecological balance across different strata of a temperate forest. [ABSTRACT FROM AUTHOR]

In the Northern Hemisphere, anthropogenic nitrogen (N) deposition contributed to the enhancement of the global terrestrial carbon (C) sink, partially offsetting CO2 emissions. Across several long‐term field experiments, this ecosystem‐level response was determined to be driven, in part, by the suppression of microbial activity associated with the breakdown of soil organic matter. However, since the implementation of emission abatement policies in the 1970s, atmospheric N deposition has declined globally, and the consequences of this decline are unknown. Here, we assessed the response of soil C storage and associated microbial activities, in a long‐term field study that experimentally increased N deposition for 24 years. We measured soil C and N, microbial activity, and compared effect sizes of soil C in response to, and in recovery from, the N deposition treatment across the history of our experiment (1994–2022). Our results demonstrate that the accumulated C in the organic horizon has been lost and exhibits additional deficits 5 years post‐termination of the N deposition treatment. These findings, in part, arise from mechanistic changes in microbial activity. Soil C in the mineral soil was less responsive thus far in recovery. If these organic horizon C dynamics are similar in other temperate forests, the Northern Hemisphere C sink will be reduced and climate warming will be enhanced. [ABSTRACT FROM AUTHOR]

Forest degradation often permits the proliferation of dense understories that inhibit the development of natural regeneration over long periods. In South American temperate rainforests, native Chusquea bamboo species become unusually competitive after logging and invade forest understories, creating dense and continuous thickets under remnant canopy tree species. In this study, we aim to evaluate how natural regeneration of native species develops after removal of the Chusquea bamboo understory and to define which microsite conditions can facilitate species' early development. To achieve this, we removed the Chusquea understory in 45 experimental units, systematically established in a 4 ha experiment located in degraded temperate forests on Chiloé Island, North‐Patagonia, Chile. We evaluated microsite conditions and monitored the natural regeneration response during 5 years. After 5 years, greater than 81% of the remnant canopy tree species were regenerating, mostly from seed, and there was a 55.5% increase in total natural regeneration (p < 0.05; increase >1 individuals/m2 yr−1), with species like Amomyrtus spp. increasing abundance by greater than 121%. Total natural regeneration presented positive significant correlations (p < 0.01) with the depth of the water table (rs: 0.40), soil carbon (rs: 0.44), nitrogen (rs. 0.41), and organic matter (rs: 0.44). We conclude that removing the Chusquea understory assists the natural recovery of degraded temperate rainforests by facilitating additional recruitment of early, mid, and late successional tree species. In this process, early and mid‐successional tree species are more specific in their microsite preferences than successionally late ones. [ABSTRACT FROM AUTHOR]

Bamboos are perennial woody grasses that display an enigmatic mix of traits. Bamboo is highly shade intolerant like early‐successional trees. Without secondary xylem, bamboos cannot continue to grow once they reach a maximum height or replace xylem damaged by hydraulic stress and must instead replace each stem after a few years using vegetative propagation via rhizomes. These traits of bamboo would appear to make them inferior to trees in competition for both light and water in all but early‐successional wet locations. However, some species competitively exclude trees and form persistent monodominant stands across large areas in tropical and temperate forests, including areas that are not mesic. Moreover, bamboo paradoxically postpones seed production for decades to over a century, and then flowers semelparously and dies synchronously. The delayed reproduction appears to be inconsistent with an early‐successional strategy to colonize disturbed areas as soon as they form, while the simultaneous death over large areas appears to be inconsistent with a late‐successional strategy to gain and hold space. Bamboo exhibits great diversity in its growth form and life histories along the tropical‐temperate geographical cline, with tropical bamboo being taller with shorter rhizome lengths and flowering interval lengths than temperate bamboo. We hypothesize that all of the above characteristics of bamboo are essential elements of competitive strategies to arrest succession in a lineage that lacks secondary xylem. To develop this Arrested Succession Hypothesis, we construct mathematical models of competition for recently disturbed areas between a tree species and a species with bamboo's enigmatic characteristics. We modeled the growth of bamboo genetic individuals from seedlings after seed germination to clonal culms at mass flowering and then placed these individuals in competition with one another and with trees in simple models of competition for light. Results explain how bamboo's traits allow it to persist in forests late in succession despite its hydraulic disadvantages, and form monodominant stands in the temperate zone, but not in tropical forests. They explain why bamboo is semelparous with synchronized reproduction, and why maximum culm size and age, reproductive interval, and rhizome length differ between the tropics and the temperate zone. [ABSTRACT FROM AUTHOR]

Documenting floristic diversity, its natural history traits and habitat affiliation offers crucial insights for developing conservation strategies and management plans for regional biodiversity. In this study, we employed random sampling technique to investigate the floristic composition, natural history trait diversity and habitat distribution among 12 major forest types spread across an elevational gradient of 350–3450 m a.s.l. in the western Himalayan region of Jammu and Kashmir. We recorded 451 species belonging to 90 families in the study region, with herbaceous growth form, perennial life span and therophyte categories dominant. We observed a steady increase in species richness from 800 to 2000 m a.s.l., with highest at 1750 m a.s.l. in the Himalayan dry temperate forest type and then a decreasing trend with elevation. In terms of species turnover, the lowest dissimilarity of 36.8% was found between the Himalayan dry temperate and Fir forests. Whereas, considering species replacement (βsne), the highest similarity of 17.3% was found between the lower western Himalayan and Himalayan dry temperate forests. This shows that beta‐diversity patterns between different forest types are mostly driven by species replacement. Multivariate analysis revealed three major groups in the entire forest species pool. Habitat‐wise, 34% species were recorded in the natural habitats, while the remaining 66% were found in human‐modified habitats (roadsides, piospheres). Our findings will improve scientific understanding of the forest vegetation of this Himalayan region and help in guiding forest policy and management. [ABSTRACT FROM AUTHOR]

Aim: Climate extremes are becoming more frequent under global warming, with substantial repercussions for vegetation growth. The degree to which climate extremes increase the risk of high‐impact events on vegetation growth is of high concern. Location: Northern Hemisphere (north of 30°N). Time Period: From 2001 to 2022. Major Taxa Studied: Plants. Methods: We utilised solar‐induced chlorophyll fluorescence (SIF) and the normalised difference vegetation index (NDVI) as proxies for vegetation growth. We performed event coincidence and sensitivity analyses to attribute satellite‐derived vegetation growth extremes to diverse climate extremes (extreme heat, cold, wet and drought) in the Northern Hemisphere. Results: Our results showed that extreme heat and cold were the main climatic extremes that induced positive and negative vegetation growth extremes north of 30°N, respectively, mainly in cold and humid ecosystems (boreal and temperate forests). Water‐related extreme events accounted for less than one‐third of vegetation extremes. The contribution of drought to positive vegetation growth extreme events (approximately 17%), mainly in cold and humid ecosystems, was even slightly higher than that of extreme wet (approximately 12%), which predominantly impacted relatively warm and arid ecosystems (croplands and temperate grasslands). We further identified potential climatic thresholds that could reverse vegetation growth responses to climate extremes (temperature is 12.5°C and climatic water deficit is ‐60 mm, approximately). We also showed that the past two decades of warming and precipitation changes did not induce a shift in the main climatic drivers of vegetation extremes across northern ecosystems. Main Conclusions: Our results emphasise the crucial role of background hydrothermal conditions in the attribution of vegetation growth extremes to diverse climate extremes across northern ecosystems and have substantial implications for predicting how Northern Hemisphere vegetation will respond to increasing climate extremes in the future. [ABSTRACT FROM AUTHOR]

The most species-rich grasslands worldwide are known from the Carpathian Mts and their periphery in East-Central Europe. They occur in forest-steppe regions, transitional between temperate forest and arid steppe biomes. Their climate, largely suitable for forests, raises questions about the origin of these grasslands. Have they been forested in the past, or locally maintained through a disturbance regime? We addressed these questions to contribute to the broader understanding of Holocene dynamics of open habitats in temperate Europe. We employed soil charcoal analysis and soil morphology to reconstruct past representation of woody species with fine spatial resolution. Our study area was Romanian Transylvania, a region renowned for a well-developed forest-steppe. Six soil profiles along a climatic gradient were assessed: four in forest-steppe grasslands, two in grasslands in adjacent forest region (forest grasslands). The results revealed profound differences between forest-steppe and forest grasslands. Forest-steppe profiles showed Phaeozems with low specific anthracomass of woody species and continuous dominance by Juniperus, suggesting a long-term presence of grasslands. Forest grasslands showed Luvisols with higher anthracomass and abundant charcoal of broad-leaved trees, indicating establishment after deforestation. The high radiocarbon ages of charcoals in basal soil horizons point to a glacial origin of soils and the link of forest-steppe grasslands to glacial forests. Siberian hemiboreal forests and related grasslands may be modern analogues of the reconstructed ecosystems, sharing many species with present day forest-steppe. We suggest that disturbances such as fire, herbivore grazing, and human activities have played an important role in shaping the forest-steppe over time, contributing to the formation of today's richest grasslands. [ABSTRACT FROM AUTHOR]

Climate warming poses major threats to temperate forests, but the response of tree root metabolism has largely remained unclear. We examined the impact of long‐term soil warming (>14 years, +4°C) on the fine root metabolome across three seasons for 2 years in an old spruce forest, using a liquid chromatography‐mass spectrometry platform for primary metabolite analysis. A total of 44 primary metabolites were identified in roots (19 amino acids, 12 organic acids and 13 sugars). Warming increased the concentration of total amino acids and of total sugars by 15% and 21%, respectively, but not organic acids. We found that soil warming and sampling date, along with their interaction, directly influenced the primary metabolite profiles. Specifically, in warming plots, concentrations of arginine, glycine, lysine, threonine, tryptophan, mannose, ribose, fructose, glucose and oxaloacetic acid increased by 51.4%, 19.9%, 21.5%, 19.3%, 22.1%, 23.0%, 38.0%, 40.7%, 19.8% and 16.7%, respectively. Rather than being driven by single compounds, changes in metabolite profiles reflected a general up‐ or downregulation of most metabolic pathway network. This emphasises the importance of metabolomics approaches in investigating root metabolic pathways and understanding the effects of climate change on tree root metabolism. Summary statement: Soil warming increases the content of amino acids and sugars in mature Norway spruce (Picea abies) fine roots, but not of organic acids. Moreover, we found that the changes in metabolite profiles were not driven by individual compounds but by a general up‐ or downregulation of most primary metabolites. [ABSTRACT FROM AUTHOR]

Terrestrial laser scanning (TLS) has become a vital tool in forestry for accurately measuring tree parameters, such as diameter at breast height (DBH). However, its application in Mexican forests remains underexplored. This study evaluates the performance of five two-dimensional DBH estimation algorithms (Nelder–Mead, least squares, Hough transform, RANSAC, and convex hull) within a temperate Mexican forest and explores their broader applicability across diverse ecosystems, using published point cloud data from various scanning devices. Results indicate that algorithm accuracy is influenced by local factors like point cloud density, occlusion, vegetation, and tree structure. In the Mexican study area, the Nelder–Mead algorithm achieved the highest accuracy (R² = 0.98, RMSE = 1.59 cm, MAPE = 6.12%), closely followed by least squares (R² = 0.98, RMSE = 1.67 cm, MAPE = 6.42%), with different outcomes in other sites. These findings advance DBH estimation methods by highlighting the importance of tailored algorithm selection and environmental considerations, thereby contributing to more accurate and efficient forest management across various landscapes. [ABSTRACT FROM AUTHOR]

The design of a sampling unit, whether a simple plot or a subplot within a clustered structure, including shape and size, has received little attention in inferential forestry research. The use of auxiliary variables from remote sensing impacts the precision of estimators from both model-assisted and model-based inference perspectives. In both cases, model parameters are estimated from a sample of field plots and information from pixels corresponding to these units. In studies assisted by remote sensing, the shape of the plot used to fit regression models (typically circular) often differs from the shape of the population elements for prediction, where the area of interest is divided into equal tessellated parts. This raises interest in understanding the effect of the sampling unit shape on the mean of variables in forest stands of interest. Therefore, the objective of this study was to evaluate the effect of circular and square subplots, concentrically overlapped and arranged in an inverted Y cluster structure, over tree density, basal area, and aboveground biomass in a managed temperate forest in central Mexico. We used a Multivariate Generalised Linear Mixed Model, which considers the Gamma distribution of the variables and accounts for spatial correlation between Secondary Sampling Units nested within the Primary Sampling Unit. The main findings of this study indicate that the type of secondary sampling unit of the same area and centroid, whether circular or square, does not significantly affect the mean tree density (trees), basal area (m2), and aerial biomass. [ABSTRACT FROM AUTHOR]

Woody debris (WD) stabilizes riverbeds, creates habitats, supports biodiversity, and enhances water quality in ecosystems. This study investigates the impact of WD on sediment characteristics and particulate organic matter (POM) accumulation in the Roztoka stream, located within a forested catchment in the Polish Carpathians. The focus is on the influence of different WD types: coarse (CWD, length > 1 m and diameter > 10 cm), fine (FWD, length < 1 m and diameter < 10 cm), and mixed (MWD, a combination of CWD and FWD) on sediment differentiation and POM accumulation. Stand age, ranging from 20 to over 120 years (in 20-year intervals), was also analyzed as a factor affecting WD structure and POM deposition. Results indicate that MWD had the greatest effect on sediment differentiation, with mean grain size (Mz) ranging from -3.91 phi to -0.95 phi. Stand age significantly influenced POM accumulation, with the highest content (19.51%) observed in age classes III and VI. Older stands (> 120 years) had a diminished effect on both WD structure and POM accumulation. This study underscores the critical role of WD in sediment differentiation and provides insights for improving the ecological function of natural streams. Although the findings are region-specific, they have broader implications for similar temperate mountainous forests. [ABSTRACT FROM AUTHOR]

Temperate forest soils are considered significant methane (CH4) sinks, but other methane sources and sinks within these forests, such as trees, litter, deadwood, and the production of volatile organic compounds are not well understood. Improved understanding of all CH4 fluxes in temperate forests could help mitigate CH4 emissions from other sources and improve the accuracy of global greenhouse gas budgets. This review highlights the characteristics of temperate forests that influence CH4 flux and assesses the current understanding of the CH4 cycle in temperate forests, with a focus on those managed for specific purposes. Methane fluxes from trees, litter, deadwood, and soil, as well as the interaction of canopy-released volatile organic compounds on atmospheric methane chemistry are quantified, the processes involved and factors (biological, climatic, management) affecting the magnitude and variance of these fluxes are discussed. Temperate forests are unique in that they are extremely variable due to strong seasonality and significant human intervention. These features control CH4 flux and need to be considered in CH4 budgets. The literature confirmed that temperate planted forest soils are a significant CH4 sink, but tree stems are a small CH4 source. CH4 fluxes from foliage and deadwood vary, and litter fluxes are negligible. The production of volatile organic compounds could increase CH4's lifetime in the atmosphere, but current in-forest measurements are insufficient to determine the magnitude of any effect. For all sources and sinks more research is required into the mechanisms and microbial community driving CH4 fluxes. The variability in CH4 fluxes within each component of the forest, is also not well understood and has led to overestimation of CH4 fluxes when scaling up measurements to a forest or global scale. A roadmap for sampling and scaling is required to ensure that all CH4 sinks and sources within temperate forests are accurately accounted for and able to be included in CH4 budgets and models to ensure accurate estimates of the contribution of temperate planted forests to the global CH4 cycle. [ABSTRACT FROM AUTHOR]