Search Results (498)

Wildfire and drought are key drivers of shrubland expansion in southwestern US landscapes. Stand-replacing fires in conifer forests induce shrub-dominated stages, and changing climatic patterns may cause a long-term shift to deciduous shrubland. We assessed change in deciduous fractional shrub cover (DFSC) in the eastern Jemez Mountains from 2019 to 2023 using topographic and Sentinel-2 satellite data and evaluated the impact of spatial scale on model performance. First, we built a 10 m and a 20 m random forest model. The 20 m model outperformed the 10 m model, achieving an R-squared value of 0.82 and an RMSE of 7.85, compared to the 10 m model (0.76 and 9.99, respectively). We projected the 20 m model to the other years of the study using imagery from the respective years, yielding yearly DFSC predictions. DFSC decreased from 2019 to 2022, coinciding with severe drought and a 2022 fire, followed by an increase in 2023, particularly within the 2022 fire footprint. Overall, DFSC trends showed an increase, with elevation being a key variable influencing these trends. This framework revealed vegetation dynamics in a semi-arid system and provided a close look at post-fire regeneration in deciduous resprouting shrubs and could be applied to similar systems. Full article

Diploid Vaccinium fuscatum is a wild blueberry species with a low chilling requirement, an evergreen growth habit, and soil adaptability to southeast US growing regions. Regardless of its potential to improve the abiotic and biotic resilience of cultivated blueberries, this species has rarely been used for blueberry breeding. One hurdle is the ploidy barrier between diploid V. fuscatum and tetraploid cultivated highbush blueberries. To overcome the ploidy barrier, vegetative shoots micro-propagated from one genotype of V. fuscatum, selected because it grew vigorously in vitro and two southern highbush cultivars, ‘Emerald’ and ‘Rebel,’ were treated with colchicine. While shoot regeneration was severely repressed in ‘Emerald’ and ‘Rebel,’ shoot production from the V. fuscatum clone was not compromised at either 500 µM or 5000 µM colchicine concentrations. Due to the high number of shoots produced in vitro via the V. fuscatum clone shoots of this clone that had an enlarged stem diameter in vitro were subjected to flow cytometer analysis to screen for induced polyploidy. Sixteen synthetic tetraploid V. fuscatum, one synthetic octoploid ‘Emerald,’ and three synthetic octoploid ‘Rebel’ were identified. Growth rates of the polyploid-induced mutants were reduced compared to their respective wildtype controls. The leaf width and length of synthetic tetraploid V. fuscatum and synthetic octoploid ‘Emerald’ was increased compared to the wildtypes, whereas the leaf width and length of synthetic octoploid ‘Rebel’ were reduced compared to the wildtype controls. Significant increases in stem thickness and stomata guard cell length were found in the polyploidy-induced mutant lines compared to the wildtypes. In the meantime, stomata density was reduced in the mutant lines. These morphological changes may improve drought tolerance and photosynthesis in these mutant lines. Synthetic tetraploid V. fuscatum can be used for interspecific hybridization with highbush blueberries to expand the genetic base of cultivated blueberries. Full article

This study investigates the spatial heterogeneity of carbon pools in young Betula sp. stands on former arable lands in the southern Moscow region, Russia. The findings could be useful for the current estimates and predictions of the carbon balance in such forest ecosystems. The research focuses on understanding the interactions between plant cover and the environment, i.e., how environmental factors such as stand density, tree diameter and height, light conditions, and soil properties affect ecosystem carbon pools. We also studied how heterogeneity in edaphic conditions affects the formation of plant cover, particularly tree regeneration and the development of ground layer vegetation. Field measurements were conducted on a permanent 50 × 50 m sampling plot divided into 5 × 5 m subplots, in order to capture variability in vegetation and soil characteristics. Key findings reveal significant differences in carbon stocks across subplots with varying stand densities and light conditions. This highlights the role of the spatial heterogeneity of soil properties and vegetation cover in carbon sequestration. The study demonstrates the feasibility of indirect estimation of carbon stocks using stand parameters (density, height, and diameter), with results that closely match direct measurements. The total ecosystem carbon stock was estimated at 80.47 t ha⁻¹, with the soil contribution exceeding that of living biomass and dead organic matter. This research emphasizes the importance of accounting for spatial heterogeneity in carbon assessments of post-agricultural ecosystems, providing a methodological framework for future studies. Full article

Carbon (C) sequestration and nitrogen (N) and phosphorus (P) accumulation in urban forest green spaces are significant for global climate regulation and alleviating nutrient pollution. However, the effects of management and conservation practices across different urban forest vegetation types on soil C, N, and P contents and stoichiometric ratios remain largely unexplored. We selected forest soils from Guangzhou, a major Metropolis in China, as our study area. Soil samples were collected from two urban secondary forests that naturally regenerated after disturbance (108 samples) and six urban forest parks primarily composed of artificially planted woody plant communities (72 samples). We employed mixed linear models and variance partitioning to analyze and compare soil C, N, and P contents and their stoichiometry and its main driving factors beneath suburban forests and urban park vegetation. These results exhibited that soil pH and bulk density in urban parks were higher than those in suburban forests, whereas soil water content, maximum storage capacity, and capillary porosity were higher in urban forests than in urban parks. Soil C, N, and P contents and their stoichiometry (except for N:P ratio) were significantly higher in suburban forests than in urban parks. Multiple analyzes showed that soil pH had the most pronounced negative influence on soil C, N, C:N, C:P, and N:P, but the strongest positive influence on soil P in urban parks. Soil water content had the strongest positive effect on soil C, N, P, C:N, and C:P, while soil N:P was primarily influenced by the positive effect of soil non-capillary porosity in suburban forests. Overall, our study emphasizes that suburban forests outperform urban parks in terms of carbon and nutrient accumulation, and urban green space management should focus particularly on the impact of soil pH and moisture content on soil C, N, and P contents and their stoichiometry. Full article

Cutting propagation is a commonly employed technology for vegetative reproduction in agricultural, forestry, and horticultural practice. The success of cutting propagation depends on adventitious root (AR) formation—a process whereby roots regenerate from stem cuttings or leaf cuttings. In this review, we summarize the distinct stages of cutting-induced AR formation and highlight the pivotal roles of plant hormones and age in this process. Jasmonic acid (JA) acts as a master trigger for promoting AR formation, while auxin serves as the core regulator, driving AR formation. Furthermore, plant age is a crucial factor determining the regenerative competence of cuttings. Notably, age and JA collaboratively modulate auxin synthesis in cutting-induced AR formation. Overall, this review not only elucidates the molecular mechanisms underlying AR formation but also provides valuable insights for improving efficiency of cutting propagation in various plant species. Full article

Dodders (Cuscuta spp.; Convolvulaceae) are parasitic weeds that pose major challenges to agriculture due to their ability to infect a wide range of host plants, extract nutrients, and transmit pathogens. Their control is especially challenging because of the seed longevity, resistance to herbicides, and the capacity for vegetative regeneration. Mechanical methods such as hand-pulling or mowing are labour-intensive and often ineffective for large infestations. Chemical control is limited, as systemic herbicides often affect the host species equally, or even worse than the parasite. Current research is exploring biological control methods, including allelopathic compounds, host-specific fungal pathogens, and epiparasitic insects, though these methods remain largely experimental. An integrated approach that combines prevention, targeted mechanical removal, and biological methods offers the most promising path for long-term management. Continued research is essential to develop effective, sustainable control strategies while exploring possible beneficial uses of these complex parasitic plants. The present review aims to thoroughly summarise the existing literature, emphasising the most recent advances and discussing future perspectives. Full article

Tropical forests face increasing threats and are often replaced by secondary forests that regenerate after disturbances. In the Atlantic Forest, this creates fragments of different successional stages. The aim of this study is to understand how soil nutrients and light availability gradients influence the species composition and structure of trees and regenerating strata in remnants of lowland rainforest. We sampled 15 plots for the tree stratum (DBH ≥ 5 cm) and 45 units for the regenerating stratum (height ≥ 50 cm, DBH < 5 cm), obtaining phytosociological, entropy and equitability data for both strata. Canopy openness was assessed with hemispherical photos and soil samples were homogenized. To analyze the interactions between the vegetation of the tree layer and the environmental variables, we carried out three principal component analyses and two redundancy analyses and applied a linear model. The young fragments showed good recovery, significant species diversity, and positive successional changes, while the older ones had higher species richness and were in an advanced stage of succession. In addition, younger forests are associated with sandy, nutrient-poor soils and greater exposure to light, while mature forests have more fertile soils, display a greater diversity of dispersal strategies, are rich in soil clay, and have less light availability. Mature forests support biodiversity and regeneration better than secondary forests, highlighting the importance of preserving mature fragments and monitoring secondary ones to sustain tropical biodiversity. Full article

Belowground buds play a vital role in the clonal propagation and structural regulation of perennial herbaceous plants, especially in alpine environments, where vegetative renewal depends heavily on bud bank dynamics. However, the interactive effects of nitrogen addition and phenological stages on bud development and aboveground branching remain poorly understood. In this study, we examined the responses of rhizome buds, tiller buds, and aboveground tiller types of Kentucky bluegrass to six nitrogen levels (0, 6, 9, 12, 15, and 18 g/m²) across five growth stages on the Qinghai–Tibet Plateau. The results showed that moderate nitrogen input (N2, 9 g/m²) significantly enhanced total bud density, particularly at the heading and maturity stages, indicating a threshold response. Aboveground reproductive tiller density peaked at N2 (9 g/m²), while vegetative and total tiller densities plateaued beyond N3 (12 g/hm²), suggesting a diminishing marginal effect of nitrogen on aboveground tiller density. Furthermore, bud density showed stage-specific correlations with tiller types: vegetative tillers were primarily influenced at the heading stage, and reproductive tillers were mainly influenced at the mature stage, with weakened associations in senescence. These findings highlight the phenological specificity and non-linear response of clonal grass regeneration to nitrogen input and provide a theoretical basis for optimizing nutrient management in cold alpine grasslands. Full article

Although the topic of trampling of alpine vegetation has been addressed by many authors in recent years, many unanswered questions still remain. The generalization of vegetation response patterns to trampling would be valuable, especially for problematic alpine areas, which are unsuitable for large hiking loads. Such an area is the limestone Belianske Tatras, which has been closed to tourists since 1978. Only one trail has been accessible in the area since 1993 as a one-way trail, and since 2008 it has been used as an educational two-way trail. Since there is renewed discussion about making the Belianske Tatras accessible to tourists, we sought answers to the following questions: (1) regenerated communities are more resistant to trampling than the native ones; (2) individual species in different communities react to trampling in the same way; and (3) some species can disappear or become extinct after being trampled. We conducted research in the form of an experiment according to the standard Cole and Bayfield protocol. We trampled three plant communities in 2008, treating them as native, and in 2022, treating them as regenerated. The regenerated communities appeared to be more resistant, although this came at the expense of some species disappearing or becoming extinct as a delayed response. Re-opening the area could be considered. Full article

In vitro micropropagation is used to rapidly shorten the breeding process of crops, such as kale, an internationally widespread winter vegetable. The aim of this study is to develop optimised micropropagation protocols for three kale varieties. First, it was determined which seed surface disinfection method resulted in the highest germination rate and the lowest infection rate. Secondly, it was investigated which of several existing Brassica protocols and one modified protocol from the literature provided the highest regeneration efficiency of kale explant types (cotyledons, hypocotyl, root, and intact seedlings as the control) after eight weeks of cultivation. Germination was highest and fastest after disinfection with 10% NaClO for 10 min for “Frostara” and at 5% for 2.5 min for “Schatteburg”. The infection rate and speed were lowest in treatments with 10% NaClO. The regeneration efficiency and number of newly formed leaves, roots, shoots, and stems varied between media, explant type, and kale variety. Most new leaves and shoots were formed when hypocotyls were used as explant type. Roots regenerated mostly more roots than shoots, stems, and leaves. A higher ratio of auxin to cytokinin in the culture medium partially increased leaf regeneration. The addition of AgNO₃ increased shoot regeneration and reduced yellowing and leaf drop. Phenotypic anomalies occurred less frequently in media with lower hormone concentrations. All tested protocols are suitable for kale micropropagation, but regeneration was highly dependent on the medium for different varieties and explant types. Therefore, this study builds a basis for future micropropagation of kale and the development of variety-specific protocols for maximum commercial success. Full article

Investigating the effects of fire disturbance on soil microbial diversity and nitrogen cycling is crucial for understanding the mechanisms underlying soil nitrogen cycling. This study examined the fire burn site of the Larix gmelinii forest in the Greater Khingan Mountains, Inner Mongolia, to analyze the impact of varying fire intensities on soil nitrogen, microbial communities, and the abundance of nitrogen cycle-related functional genes after three years. The results indicated the following findings: (1) Soil bulk density increased significantly following severe fires (7.06%~10.84%, p < 0.05), whereas soil water content decreased with increasing fire intensity (6.62%~19.42%, p < 0.05). The soil total nitrogen and ammonium nitrogen levels declined after heavy fires but increased after mild fires; (2) Mild fire burning significantly increased soil bacterial diversity, while heavy fire had a lesser effect. Dominant bacterial groups included Xanthobacteraceae, norank_o_norank_c_AD3, and norank_o_Elsterales. Norank_o_norank_c_AD3 abundance decreased with burn intensity (7.90% unburned, 3.02% mild fire, 2.70% heavy fire). Conversely, norank_o_Elsterales increased with burning (1.23% unburned, 5.66% mild fire, 5.48% heavy fire); (3) The abundance of nitrogen-fixing nifH functional genes decreased with increasing fire intensity, whereas nitrification functional genes amoA-AOA and amoA-AOB exhibited the opposite trend. Light-intensity fires increased the abundance of denitrification functional genes nirK, nirS, and nosZ, while heavy fires reduced their abundance; (4) The correlation analysis demonstrated a strong association between soil bacteria and denitrification functional genes nifH and amoA-AOA, with soil total nitrogen being a key factor influencing the nitrogen cycle-related functional genes. The primary bacterial groups involved in soil nitrogen cycling were Proteobacteria, Actinobacteria, and Chloroflexi. These findings play a critical role in promoting vegetation regeneration and rapid ecosystem restoration in fire-affected areas. Full article

Passiflora caerulea L., commonly known as the blue passionflower, is traditionally grown as an ornamental plant, but has a diverse chemical composition resulting in a wide range of biological activities that determine its pharmacological properties and use in medicine. Traditional propagation methods, including seed germination and vegetative cuttings, are often inefficient due to low germination rates, susceptibility to pathogens, and slow growth. In particular, P. caerulea presents significant challenges in germination due to its slow development. In this context, in vitro cultivation is used to enable rapid, large-scale plant production while maintaining genetic fidelity. The study of Passiflora tissue cultures began in 1966 and has since attracted increasing attention from researchers around the world. However, despite growing interest, studies specifically focused on the in vitro propagation of P. caerulea remain limited. This review aims to summarize existing knowledge on the main techniques used for in vitro culturing and propagation of P. caerulea, including organogenesis, somatic embryogenesis, and callogenesis. Particular attention is paid to the key factors that influence the initiation, growth, and regeneration of cultures, including the type of explant, the composition of the media, and the environmental conditions. Advances in the in vitro cultivation of P. caerulea have greatly improved the understanding and propagation of this species. Although in vitro cultivation offers several advantages, it is crucial to conduct thorough research on the selection of explants, their age, and the appropriate culture media to ensure optimal growth and development. Full article

Wildfires play a pivotal role in shaping and regulating the structural characteristics of forest ecosystems. This study examined post-fire vegetation dynamics following the 2020 Bighorn Fire in the Santa Catalina Mountains, Arizona, USA, by integrating pre- and post-fire airborne LiDAR data with Landsat-derived burn severity indices from 2019 to 2024. We analyzed structural and functional vegetation traits across 12,500 hectares to assess the changes pre- to post-fire, and to evaluate how these changes were influenced by the burn severity. We applied a correlation analysis to explore the relationships among the structural variables across different vegetation cover types. Non-parametric LOESS regression revealed that the dNBR was more strongly associated with changes in the tree density than with vertical structural attributes. The functional recovery, indicated by the NDVI, generally outpaced the structural recovery captured by the NBR. Densely forested areas experienced greater declines in vegetation volumes and slower regeneration, whereas herbaceous and sparsely vegetated areas showed a more rapid, but compositionally distinct, recovery. The divergence between the NDVI and NBR trajectories underscores the importance of integrating structural and functional indicators to comprehensively assess the post-fire ecosystem resilience and inform targeted restoration efforts. Full article

Tropical forests harbor a significant portion of global biodiversity but are increasingly degraded by human activity. Assessing restoration efforts requires the systematic monitoring of tropical ecosystem status and recovery. Satellite-borne synthetic aperture radar (SAR) supports monitoring changes in vegetation structure and is of particular utility in tropical regions where clouds obscure optical satellite observations. To characterize tropical forest recovery in the Lowland Chocó Biodiversity Hotspot of Ecuador, we apply over a decade of dual-polarized (HH + HV) L-band SAR datasets from the Japanese Space Agency’s (JAXA) PALSAR and PALSAR-2 sensors. We assess the complementarity of the dual-polarized imagery with less frequently available fully-polarimetric imagery, particularly in the context of their respective temporal and informational trade-offs. We examine the radar image texture associated with the dual-pol radar vegetation index (DpRVI) to assess the associated determination of forest and nonforest areas in a topographically complex region, and we examine the equivalent performance of texture measures derived from the Freeman–Durden polarimetric radar decomposition classification scheme applied to the fully polarimetric data. The results demonstrate that employing a dual-polarimetric decomposition classification scheme and subsequently deriving the associated gray-level co-occurrence matrix mean from the DpRVI substantially improved the classification accuracy (from 88.2% to 97.2%). Through this workflow, we develop a new metric, the Radar Forest Regeneration Index (RFRI), and apply it to describe a chronosequence of a tropical forest recovering from naturally regenerating pasture and cacao plots. Our findings from the Lowland Chocó region are particularly relevant to the upcoming NASA-ISRO NISAR mission, which will enable the comprehensive characterization of vegetation structural parameters and significantly enhance the monitoring of biodiversity conservation efforts in tropical forest ecosystems. Full article

The Orchidaceae family is of significant decorative, pharmaceutical, alimentary, and cultural importance worldwide. This family is very vulnerable due to illegal looting, habitat destruction, and climate change. The development of new hybrids helps meet the demand for specimens that possess outstanding appearance, fragrance, and resistance characteristics and may reduce illegal looting. The objective of this research was to investigate the in vitro propagation of the hybrid Rhyncattleanthe Queen Bee JLA 1 (Rth. Queen Bee JLA 1). Shoot induction was performed with germinated seedlings that were 1 cm in length on semi-solid MS medium with different 6-Benzylaminopurine (BAP), 1-Naphthaleneacetic acid (NAA), 3-Indoleacetic acid (IAA), and 3-indolebutyric acid (IBA) concentrations. Micropropagation was conducted using a temporary immersion system (TIS), a liquid continuous immersion system (CIS), and a conventional semi-solid system (SSS). Afterwards, all regenerated seedlings underwent an acclimatization stage. The highest numbers of shoots (7.04) and leaves (14.28) were obtained with the combination of 1.5 mg L⁻¹ BAP and 0.4 mg L⁻¹ NAA, while the addition of 0.4 mg L⁻¹ IBA in combination with 1.5 mg L⁻¹ BAP enhanced the length of stems (2.12 cm) and leaves (1.88 cm). TIS produced the highest number of shoots (15.68), leaves (22.92), stem length (5.94 cm), and number of leaves (3.50) in seedlings analyzed. The combination of growth regulators BAP and NAA together with the temporary immersion system influenced both the development of the vitroplants and their vegetative development after acclimatization of the hybrid Rth. Queen Bee JLA1 orchid. Full article