Search Results (687)

This study quantified total biomass stocks in Carrasco (CAR, n = 12), a dense tropical deciduous vegetation type from the Brazilian semi-arid region for which biomass information remains scarce. We also evaluated differences in floristic composition, diversity, structure, and biomass allocation patterns relative to Cerrado sensu stricto (CSS, n = 40). Forest inventories were conducted in southeastern Brazil. Woody biomass was estimated using a regional allometric equation. Roots were sampled in a position adjacent to the plots, and litter was collected at the center of each plot using a frame. Necromass was assessed along a linear transect corresponding to the length of each plot using the line-intersect method. Biomass differences between vegetation types were assessed using generalized linear and mixed-effects models (GLMs and GLMMs). Total biomass reached 45.24 Mg ha⁻¹ in CSS and 59.01 Mg ha⁻¹ in CAR. In CSS, woody biomass predominated (20.47 Mg ha⁻¹; 45%), followed by roots (18.47 Mg ha⁻¹; 41%), litter (5.49 Mg ha⁻¹; 12%), and necromass (0.81 Mg ha⁻¹; 2%). In CAR, roots were the dominant component (32.37 Mg ha⁻¹; 55%), followed by woody biomass (16.57 Mg ha⁻¹; 28%), litter (8.39 Mg ha⁻¹; 14%), and necromass (1.68 Mg ha⁻¹; 3%). CSS and CAR shared only 10% of their species and showed significant differences in total biomass (TB) and belowground biomass (BGB), while aboveground biomass (AGB), aboveground woody biomass (AGWB), litter, and necromass did not differ significantly (α = 0.05). The BGB/AGWB ratio was <1 in CSS and >1 in CAR, resembling global patterns of savanna/shrubland and grassland formations, respectively. Considering the sampling design adopted, despite the higher stem density in CAR, larger individuals in CSS compensated for structural differences, resulting in similar aboveground biomass stocks. Our findings reinforce the floristic and structural distinctiveness of Carrasco and reveal contrasting biomass allocation strategies, with a strong dominance of belowground biomass in CAR. These results demonstrate that aboveground-based assessments can substantially underestimate total biomass in semi-arid transitional vegetation and highlight the need to incorporate non-forest ecosystems into biomass inventories, conservation planning, and climate change mitigation strategies. Full article

Buds are a critical stage in the annual growth–dormancy cycle of perennial woody plants and are essential for survival and biomass accumulation. To safeguard these structures, trees employ both physical and chemical protection. Although Populus buds are known to contain rich phytochemistry, population-level variation remains largely unexplored. Here, we characterized bud phytochemistry across a population of Populus trichocarpa natural variants using gas chromatography–mass spectrometry and examined the antifungal properties of bud extracts. In the reference genotype Nisqually-1, a total of 32 lipophilic metabolites were detected, belonging to four chemical groups: terpenoids, phenylpropanoids, linear hydrocarbons, and others. Analysis of 49 additional P. trichocarpa natural variants revealed both shared features and substantial variation. All lines contained metabolites from the phenylpropanoid, linear hydrocarbon and terpenoid classes, which consistently dominated the profiles. However, quantitative differences in individual metabolites and relative class abundances distinguished the lines, allowing them to be grouped into three chemotypic clusters. To assess potential biological implications of phytochemical variance, we tested antifungal activity of bud extracts against the pathogenic fungus Fusarium oxysporum. Extracts from all 50 lines significantly inhibited fungal growth compared with controls. Correlation analyses between metabolite abundance and inhibition strength identified candidate metabolites that were most strongly associated with antifungal activity. Together, these findings reveal both conserved and variable components of bud phytochemistry in P. trichocarpa. The observed chemical diversity and consistent antifungal effects suggest that bud metabolites contribute to defense and may reflect adaptation across natural populations. Full article

Accurately quantifying aboveground biomass (AGB) in tropical forest enrichment plantations remains challenging, particularly in managed regenerating stands where tree crown architecture, size structure, and species composition differ from the datasets used to calibrate classical allometric equations. Here, we assess whether AGB in tropical forest enrichment plantations can be estimated more accurately by combining tree-specific woody volume reconstructed from mobile laser scanning (MLS) with an explicit foliar-biomass component. We combined destructive measurements from 83 trees with high-resolution MLS point clouds to quantify biomass components, calibrate leaf-mass models, and assess the contribution of foliage to total AGB. Stems accounted for most of the biomass (65%), whereas leaves contributed only 3% on average. Among the models tested, Model 3, which included DBH, projected crown area, and wood density, showed the best performance (R² = 54.4%; RMSE = 2.43 kg). The main gain relative to regional (−20.4%) and pantropical (−25.6%) allometric equations came from the use of MLS-derived woody volume combined with species wood density, whereas the inclusion of predicted leaf biomass provided a moderate additional correction to the remaining bias. These results highlight the importance of canopy structure for biomass estimation in enrichment plantations and managed regenerating stands and support the use of LiDAR data as a robust alternative for AGB assessment in this context. Full article

The expansion of Moso bamboo (Phyllostachys edulis) significantly alters the spatial configuration of surrounding trees, leading to dynamic shifts in the spatial distribution of coarse woody debris (CWD). Investigating the spatial patterns of CWD during bamboo expansion can reveal the dynamic mechanisms of forest communities in this process, thereby providing scientific insights for forest management and conservation. In this study, conducted within the Yangjifeng Biodiversity Monitoring Large Plot, all trees with a diameter at breast height (DBH) ≥ 1 cm within the plots were tagged and important variables were measured, including DBH, tree height, and spatial attributes. Coarse woody debris (CWD) with a DBH ≥ 10 cm was also measured, including DBH, diameters at both ends, length, and spatial attributes. Based on the importance values of tree species in each 20 m × 20 m plot—where an importance value comprehensively measured a species’ relative abundance, frequency, and dominance in the community—the sample plots were divided into three continuous sample transects: evergreen broad-leaved forest (EBF), bamboo–broadleaf mixed forest (BMF), and Phyllostachys edulis forest (PEF). Ripley’s ‘g’-function was employed to analyze the spatial patterns and associations of CWD across these three forest types. A random sampling approach was used to collect CWD samples for the measurement and calculation of carbon storage. Three key findings emerged. (1) With the expansion of Moso bamboo, the biomass and carbon storage of standing dead trees both decrease. The biomass is highest in EBF, followed by BMF and PEF. However, carbon storage is greatest in BMF and lowest in PEF. (2) With the expansion of Moso bamboo, the distribution of CWD became increasingly uniform in PEF; analysis of the overall spatial pattern of CWD indicated that with increasing spatial scale, CWD changed from an aggregated to a random distribution across all three forest types, with a pattern scale of approximately 10 m. In EBF, the CWD of Moso bamboo exhibited a random distribution at all spatial scales. Additionally, CWD across different diameter classes, decay stages, and types changed from aggregated to random distributions as the spatial scale increased, with a reduction in aggregation intensity correlated with larger diameter classes. (3) Finally, we found an almost exclusively negative spatial association between living trees and CWD across all scales, and this negative correlation may be attributed to the absence of new tree growth following tree mortality. Collectively, our findings demonstrate that during Moso bamboo expansion, the spatial distribution of CWD changes from aggregated to random, while maintaining a significantly negative spatial association with living trees. This reveals the dynamic changes in the spatial patterns of CWD during community development, thereby providing a scientific basis for the forest management of subtropical evergreen broadleaf forests and bamboo management and control. Full article

Protein turnover is essential for cellular metabolism, organelle biogenesis, stress adaptation, and ultimately the viability of cells and tissues. Papain-like cysteine proteases (PLCPs) are one of the vital components in protein degradation. PLCPs have been reported to act in senescence-associated proteolysis, but their roles in vegetative growth remain unclear. We identified PtCP1, an AALP-like PLCP in Populus tomentosa, localized to the vacuole and acid-triggered activated. CRISPR/Cas9-generated loss-of-function mutant (d7) showed dwarfism and non-stomatal photosynthetic limitations. On the other hand, the gain-of-function line (EM, deleted ERFNIN domain) exhibited accelerated growth and enhanced photosynthetic parameters. We showed d7 had the accumulation of Rubisco, which was the most important protein in photosynthetic carbon fixation. Transcriptomics revealed dysregulated carbon metabolism in d7. This data supported PtCP1-mediated proteolysis regulated photosynthetic carbon assimilation via altered Rubisco turnover, and then it increased the biomass accumulation during vegetative growth in woody plants. Full article

As a typical mountain ecosystem in the western Tianshan Mountains, the Ili River Valley possesses abundant vegetation resources. Soil nematodes are effective biological indicators for evaluating soil micro-food webs. Nevertheless, the response mechanisms of nematode community structure to distinct vegetation types, especially native trees and forest-edge shrubs, remain poorly understood in this region. In this study, two dominant tree species (Picea schrenkiana and Malus sieversii) and two forest-edge shrub species (Berberis heteropoda and Berberis sibirica) were investigated. We analyzed the composition, diversity, and energy structure of rhizosphere soil nematodes and further compared their differences among plant species. The results indicated that tree rhizospheres had significantly higher amounts of nitrate nitrogen ($\mathrm{N}{\mathrm{O}}_3^{-}$-N and microbial biomass carbon (MBC), along with a lower amount of extractable organic carbon/extractable total nitrogen (EOC:ETN) than shrub rhizospheres (p < 0.05). Picea schrenkiana (PS) exhibited greater root carbon storage, higher root biomass, and a higher root carbon-to-nitrogen ratio (RC:RN) than Berberis heteropoda (BH) and Berberis sibirica (BS) (p < 0.05). The genus Chiloplacus dominated the nematode community across all four woody plants. The relative abundance of omnivore-predatory nematodes was markedly higher in shrubs (BH and BS) than in trees (PS and MS). The soil food webs of PS and MS were degraded, whereas shrub food webs were in a transitional state between structured and degraded habitats. Shrubs presented a higher maturity index, structural metabolic footprint, and energy flux of omnivore-predatory nematodes, but a lower energy flux of bacterivorous nematodes. Additionally, PS had the highest nematode carbon use efficiency (NCUE) and the lowest energy flux uniformity (U). $\mathrm{N}{\mathrm{O}}_3^{-}$-N extractable total nitrogen (ETN), soil organic carbon (SOC), and root traits were the primary factors driving variations in nematode communities and carbon indicators. Therefore, nematode carbon indicators closely associated with soil carbon and nitrogen cycling have the potential to serve as sensitive auxiliary biological metrics for evaluating material cycling and energy flow in pure forests and shrub ecosystems. This study provides empirical support for the assessment of regional ecosystem stability. Full article

The transition to renewable carbon resources has positioned lignocellulosic biomass as a key feedstock for sustainable fuel and chemical production; however, its intrinsic recalcitrance limits efficient conversion. Dilute acid pretreatment functions as a homogeneous Brønsted acid catalytic system that selectively depolymerizes hemicellulose and disrupts lignin–carbohydrate complexes, while competing with consecutive sugar dehydration reactions, thereby enhancing downstream processing. This review presents a feedstock-specific analysis of acid catalyzed biomass deconstruction across agricultural residues, woody biomass, and energy crops, with xylose yield employed as a kinetically and mechanistically relevant descriptor of catalytic performance. By correlating proton activity, reaction severity, diffusion constraints, lignin chemistry, and mineral interference with observed conversion behavior, the work establishes a structure–reactivity–performance framework for biomass dependent hydrolysis. Particular attention is given to competing dehydration and condensation pathways that reduce pentose selectivity and generate fermentation inhibitors. The analysis identifies optimal severity windows for maximizing catalytic efficiency while suppressing degradation reactions and provides guidance for feedstock-tailored pretreatment and next-generation acid catalytic systems and reactor configurations in integrated biorefineries. Full article

Rapid alkalinization factor (RALF) peptides are recognized as multifunctional regulators of plant stress responses, yet their roles in woody species remain poorly defined. Here, we identified a RALF22-like peptide from poplar ‘Shanxin’ (Populus davidiana × P. bolleana; PdbRALF22-like) and investigated its roles in salt tolerance and disease resistance. Synthetic PdbRALF22-like peptide elicited a rapid ROS burst in poplar leaf discs. In Nicotiana benthamiana, which was otherwise unresponsive to the peptide, transient expression of either of two poplar FERONIA-like receptor kinases (PdbFER-like-1 and PdbFER-like-2) enabled peptide-triggered ROS production, consistent with receptor-matched responsiveness in a heterologous context. Using CRISPR/Cas9, we generated a PdbRALF22-like knockout line and assessed salt tolerance in vitro and soil-grown assays. Under salinity, the mutant showed sustained rooting at high NaCl concentrations and improved growth relative to wild type. After 0.2 M NaCl treatment, soil-grown mutant plants exhibited reduced wilting and leaf injury. Evans Blue, DAB, and NBT staining indicated reduced membrane damage and lower accumulation of hydrogen peroxide and superoxide in the mutant. Significantly, the same knockout line displayed increased susceptibility to infection by the poplar leaf spot fungus, with larger lesions and higher pathogen biomass, accompanied by reduced ROS output and lower induction of the defense marker gene PdbPR1. Collectively, PdbRALF22-like negatively regulates salt tolerance while contributing positively to disease resistance, and represents a regulatory node linking salinity tolerance and disease susceptibility in poplar ‘Shanxin’, with poplar FER-like receptors providing a plausible route for peptide-triggered ROS signaling. This work expands our understanding of RALF peptide signaling in woody plants. Full article

Seed pre-treatment is imperative for breaking the seed dormancy of some perennial species. The addition of soil amendments might be helpful in supporting seed germination and growth by available essential plant nutrients. This research investigated the effects of different pre-treatment and soil amendments on the germination, growth, and physiological performance of radhachura (Caesalpinia pulcherrima L.), an important ornamental and multipurpose woody shrub. Four pre-treatments and five soil amendments were applied in a CRD (Completely Randomized Design) arrangement to evaluate their individual and combined impacts under controlled nursery conditions. The ANOVA result revealed that seed germination indices of radhachura were mostly influenced by soil amendment rather than the seed pre-treatment. Among the soil amendments, vermicompost had a more profound impact on germination speed, Timson’s index and peak value, which had a similar effect to NPK application. Soil organic amendments positively affected growth, with vermicompost exerting the greatest influence on multiple germination traits that may support the early growth of radhachura, while biochar and compost maximized certain root and plant-length traits. Pearson correlations and PCA (first seven PCs explaining 76.2% variation) revealed the strong integration of late biomass, plant length, and root development, identifying vermicompost as key enhancers of multivariate vigor in radhachura seedlings. It might be concluded that C. pulcherrima L. species germination and growth was mostly influenced by soil amendment rather than seed pre-treatment. The study highlights that integrated nursery practices combining appropriate pre-treatment and soil amendments can enhance the germination success of radhachura. Full article

Intensifying drought stress under global climate change poses a significant threat to woody plants, highlighting the critical need to identify key genes conferring drought tolerance. Here, we characterized PsnSAUR6, a Small Auxin Upregulated RNA (SAUR) family gene from poplar (Populus simonii × P. nigra) that is responsive to drought and abscisic acid (ABA). Overexpression of PsnSAUR6 in transgenic tobacco conferred superior drought tolerance, evidenced by increased biomass, enhanced root elongation, improved stomatal regulation, and favorable physiological responses, including higher proline content and peroxidase (POD) activity but lower malondialdehyde (MDA). Transcriptome analysis revealed that under water deficit, PsnSAUR6 suppressed the ABA negative regulator PP2C37 while upregulating key antioxidant defense-related transcription factors (ERF020, NAC83, MYB2) and the potassium transporter HAK5. Collectively, these findings establish PsnSAUR6 as a positive regulator in ABA-mediated drought adaptation, presenting it as a promising genetic target for enhancing the climate resilience of woody plants. Full article

The increasing demand for energy, the finite nature of fossil fuel resources, and the necessity to reduce greenhouse gas emissions have intensified research on renewable energy sources of plant origin. Among potential energy feedstocks, herbaceous biomass has attracted growing interest due to its high productivity, rapid growth, and widespread occurrence. The aim of this study was to evaluate the energy potential of select sedge species (Carex spp.) commonly occurring in Poland as an alternative to fossil fuels. Aboveground biomass of eight sedge species was collected from natural habitats located in the Warta River valley. Cellulose, lignin, holocellulose, hemicellulose, and ash content in the biomass was determined. In addition, key energy parameters, namely net calorific value and gross calorific value, were analyzed. Differences among species were assessed using one-way analysis of variance, while similarities were explored using hierarchical clustering methods. The results revealed significant interspecific variation in both chemical composition and energy properties. Most analyzed sedge species had favorable lignocellulosic composition and energy parameters comparable to those of woody biomass, particularly willow and poplar. In contrast, Carex riparia was distinguished by a high ash content and lower calorific values, limiting its suitability for energy applications. Overall, the findings indicate that select Carex species may represent a valuable renewable feedstock for energy production, especially in the context of local and decentralized biomass-based energy systems. Full article

Primary succession following glacier retreat provides a natural system for testing whether soil development simply shifts fine roots along a single acquisitive–conservative axis orinstead changes the nutrient-acquisition pathway that dominates at the community level. We hypothesized a stage-dependent sequence, from substrate-limited exploration, to transient morphological capture, and finally to rhizosphere-mediated biochemical mobilization. To test this idea, we quantified fine-root morphology, absorptive-transport partitioning, anatomy, phosphatase activity, exudation, community-scale belowground structure, and soil and rhizosphere properties across woody communities representing approximately 20, 40, and 90 years since deglaciation in the Hailuogou Glacier foreland. Across succession stages, bulk density and pH declined, whereas field capacity, soil carbon, and soil nitrogen increased, indicating rapid development of the belowground resource environment. Fine-root strategies did not fall along a single acquisitive–conservative continuum. Instead, morphological nutrient capture peaked at intermediate succession: the 40-year stage had the highest specific root length, specific root area, absorptive-to-transport root length ratio, and root nitrogen concentration. In contrast, the 90-year stage showed lower specific root length but higher dry matter content, thicker cortex, greater standing fine-root biomass, larger rhizosphere volume, higher phosphatase activity, and greater area-based carbon exudation. This late-successional syndrome coincided with stronger extracellular enzyme activity, larger dissolved organic carbon and nitrogen pools, and higher microbial biomass, despite negative net nitrogen mineralization. Species-level analyses showed that biochemical-input traits were jointly shaped by successional stage, species identity, and their interaction. Together, these results show that primary succession did not simply increase or decrease root acquisitiveness. Instead, as soils developed, it changed the nutrient-acquisition pathway that dominated, with direct implications for nutrient cycling and vegetation dynamics in rapidly developing glacier-foreland ecosystems. Full article

The black carbon (BC) emission resulting from human activity comes mainly from fossil fuels and solid biomass burning, as well as transport fuels due to incomplete combustion. The biggest sources of BC pollution are currently diesel transport and domestic heating appliances burning solid fossil fuels or biomass. Firewood and pellet fuels were used for this BC research. The study used four domestic heating appliances using wood and agricultural waste pellets, as well as several types of firewood. The tests used a gravimetric particulate analysis method to determine the total amount of particulate matter. In further physical and chemical analyses, the emissions are broken down into components, i.e., substances of known composition that can be separated from the sample and weighed. In our study, the BC emissions varied from 0 to 120 mg/MJ depending on the type of boiler (automatic or manual), the combustion mode (based on oxygen supply), and the type of fuel. Emissions varied from 0–8 mg/MJ in a modern pellet-fired and automatically-controlled boiler, and from 1–25 mg/MJ in a wood-fired water heating boiler, with the highest emissions found for softwood (spruce). In the pellet stove with automatic feeding and control, BC emissions varied between 1 and 120 mg/MJ, with the highest emissions detected for wood pellets, and in the wood-burning fireplace, the emissions varied between 6 and 80 mg/MJ, with the highest emissions detected for birch firewood. Full article

Wildfires are key drivers of Mediterranean forest dynamics, yet post-fire recovery and carbon cycling in coastal dune systems remain poorly understood, particularly under invasive species pressure. This study quantified how microtopography and dominant woody species shape vegetation recovery, carbon stocks, and soil CO₂ efflux in a Pinus pinaster plantation burned in 2017 in coastal Portugal, during the fifth post-fire hydrological year (2021–2022). Vegetation composition, aboveground biomass, litter, soil organic matter and total organic carbon were measured across dune crests and slacks, and soil respiration was repeatedly assessed under native—Halimium halimifolium—and exotic invasive—Acacia longifolia—woody species using a closed-chamber system. Woody cover was higher on crests, whereas slacks supported greater herbaceous cover and stronger increases in soil organic matter, with litter dominating biomass and carbon pools in all microsites. A. longifolia showed marked demographic expansion and higher soil respiration than the native shrub, while mixed-effects models revealed non-linear, interacting effects of soil moisture and temperature on CO₂ efflux. Overall, post-fire recovery and carbon dynamics were spatially heterogeneous and increasingly controlled by invasion, underscoring the need for microsite-specific restoration and early invasive control to safeguard carbon sequestration and native forest resilience in Mediterranean coastal dunes. Full article

Old-growth forests play a vital role in the conservation of terrestrial biodiversity, though they are rare and increasingly threatened worldwide. The Mediterranean region hosts notable examples of these ecosystems, but information about their location, structure, and biodiversity is still largely incomplete. In this work, we tested the hypothesis that the region of Tuscany (Italy) harbors forest sites with old-growth characteristics in light of the EU indicators and the Italian ministerial guidelines. Accordingly, data on stand structural and plant diversity variables were collected in 27 plots located in pre-selected sites across different forest types of the region. As a result, 12 sites were inventoried that can be proposed as candidates for the national network of old-growth forests. These were largely unknown, ca. 10–300 ha in surface and encompassing five main forest types across 14 Natura2000 habitats. All stands have reached the mature or nearly senescent stage thanks to natural dynamic processes for over 70 years after the cessation of substantial anthropogenic disturbances. The structural heterogeneity index (SHI), based on living and deadwood biomass variables, was relatively high (66.2–84%). However, structural variables depended on forest type, thus on bioclimatic context and dominant tree species. Stands with beech and mountain conifers showed more pronounced old-growth characteristics than Mediterranean stands due to a faster recovery dynamic after cessation of disturbance. As many as 193 vascular plant taxa were recorded, with 16 species occurring with trees ≥ 50 cm in diameter. Forest specialist taxa, either woody or herbaceous, were prevalent, but numerous generalists also occurred in the gaps. Ancient forest species were also well represented, supporting the long temporal continuity of the forests. This work advances knowledge about forest sites with old-growth characteristics in southern Europe, contributing to the implementation of the national network and the EU Biodiversity Strategy 2030. Strict protection of these sites is necessary to allow the forest stands to fully reach the old-growth stage in the next decades, despite the negative influence of climate change. Full article