Search Results (126)

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

Wildfires have had measurable impacts on pollen dispersal in some areas; both facilitation and potential barriers to pollen movement have been reported. These dispersal dynamics in turn affect population genetics and reestablishment of seed-producing plants, at times significantly impacting the successional trajectory of the area in question. However, research on post-fire pollen distribution and occurrence is lacking for the boreal and sub-boreal forests of western Canada, and many communities that have been heavily impacted by wildfire remain concerned about the future forest landscape of these areas. We analyzed post-fire pollen samples from unburned and severely burned sub-boreal spruce stands in north-central British Columbia four years after a major wildfire. We used pollen traps to measure the occurrence and abundance of pollen types from four important plant families: Asteraceae, Ericaceae, Onagraceae, and Pinaceae families, to address specific concerns of the First Nation communities with territories overlapping the Shovel Lake wildfire burned area. Pinaceae pollen was found across all traps and was observed as the most dominant pollen type at all study sites, while pollen belonging to other families was found less frequently. No significant differences in pollen occurrence or abundance were found between burn severities, despite differences in the plant communities; however, plant and pollen abundance were found to be positively correlated to one another. These results may indicate that, as previously noted in other conifer-dominated forests, openings of the forest landscape by wildfire may facilitate rather than hinder pollen movements. Understory species should be studied in more detail as the effect of wildfire on pollen transport may vary between taxa and pollination syndromes. Full article

Old-growth forests are rare in Europe, yet they play a critical role in biodiversity and carbon storage. This study examines the structural dynamics of the Janj old-growth forest in the Dinaric Alps using repeated field measurements from 2011 and 2021 at 39 systematically arranged 12 m radius plots. All trees (DBH ≥ 7.5 cm), regeneration (10 cm height to 7.5 cm DBH), and coarse woody debris (CWD) were assessed. Results revealed that total basal area declined by 3.5 m² ha⁻¹ over the decade, primarily driven by significant reductions in stem density for silver fir (p = 0.001) and Norway spruce (p = 0.001). In contrast, European beech maintained a stable basal area throughout the study period. Moreover, silver fir exhibited a significant increase in mean diameter (p = 0.032) and a pronounced rise in regeneration individuals (t = 3.257, p = 0.002). These findings underscore a gradual compositional shift towards European beech dominance, with conifers facing higher mortality in larger diameter classes. The substantial volume of CWD (463 m³ ha⁻¹) highlights advanced decay dynamics consistent with mature forest conditions. This study emphasizes the value of repeated measurements to capture subtle yet important successional changes in primeval forests, which is essential for conservation planning and sustainable forest management. Full article

In subtropical regions of China, the expansion of Moso bamboo has become increasingly prominent, resulting in massive mortality of original trees in adjacent forest stands. Significant changes have also occurred in the population characteristics and spatial distribution patterns of these native tree species. This study aims to examine the impacts of Moso bamboo (Phyllostachys edulis) expansion on the successional dynamics of coniferous and broad-leaved mixed forests. Three sample plots were successively set up in the transition zone from bamboo to conifer and broad-leaved forest, including conifer and broad-leaved mixed forest (CF), transition forest (TF), and Moso bamboo forest (MF); a total of 72 10 m × 10 m quadrats (24 per forest type) were included. The species composition, diameter class structure and distribution pattern of living stems and snags (dead standing stems) were studied. The results showed that during the late expansion phase of bamboo, the density of living stems and snags separately increased by 2234 stems·ha⁻¹ and 433 stems·ha⁻¹, basal area increments of 23.45 m²·ha⁻¹ and 7.81 m²·ha⁻¹. The individuals with large diameter in living stems and snags gradually decreased, and the distribution range of the diameter steps mainly narrowed to 10–15 cm. On the scale of 0–10 m, the spatial pattern of standing stems changed from random and weak aggregation distribution to strong aggregation distribution and then to weak aggregation and random distribution in the three stands, while the overall distribution of snags in the three stands was random. The spatial correlation between living stems and snags evolved from uncorrelated in CF, to significant positive correlation in TF, and then to positive correlation and uncorrelation in MF. These results indicated that the bamboo expansion accelerated the mortality rate of the original tree species, leading to the diversity of tree species decreased, the composition of diameter classes was simplified, the degree of stem aggregation increased, and intra- and inter-species competition became the main reasons for tree death. Full article

Variation patterns in plant functional traits and their interrelationships play a crucial role in understanding species coexistence mechanisms and ecological differentiation within local plant communities. However, the dynamic patterns of plant functional traits across different forest successional stages remain insufficiently understood. Here, we investigated the woody species composition of subtropical evergreen–deciduous broadleaved mixed forest across 75 plots, representing three successional stages (20-year-old secondary forest, 35-year-old secondary forest, and old-growth forest (>80 years)), in Xingdoushan and Mulinzi National Nature Reserves, Hubei Province, Central China. We measured four functional traits of woody plants: leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), and wood density (WD). For each different age plant community, we calculated (1) species abundance-weighted mean community trait values, and (2) species-level mean trait values. We applied trait gradient analysis to partition and assess correlations of four functional traits across communities of different successional stages, separating within-community (α components) and between-community (β components) variation. To quantify the extent to which environmental constraints influence trait expression, we used the ecological constraint index (C_i). The results revealed significant variation in the four functional traits across communities at different successional stages. Community-level mean LA and SLA decreased significantly with age, WD increased significantly with age, and there was no significant relationship between LDMC and age. The α trait components consistently varied more widely than β components at different successional stages, indicating that biological competition dominates the assembly of local forest communities across various successional stages. Correlations between the four functional traits were dynamically adjusted with the study scale (community-level and species-level) and forest age. The ecological constraints on the four functional traits varied significantly across forest successional stages, with SLA being subject to the strongest constraints. Our findings reveal that biotic competition predominantly shapes community assembly during the succession of subtropical evergreen–deciduous broadleaved mixed forests, while stronger ecological filtering in old-growth stands underscores their role in maintaining ecosystem stability. These insights support more effective conservation and restoration strategies. Full article

Retrogressive succession alters soil conditions and microbial community dynamics in cold-region wetlands, yet its ecological implications remain understudied. This study explored the structure and function of soil microbial communities across three successional stages: swamp (SP), swamped meadow (SM), and meadow (MW). High-throughput 16S rRNA gene sequencing identified 2852 operational taxonomic units (OTUs), with 1682 shared among all stages (58.85%). Alpha diversity indices, including Shannon, Chao, ACE, and Sobs, were significantly higher in MW, with the Shannon index increasing by approximately 32% compared to SP, indicating enhanced richness and evenness. In contrast, Simpson and Coverage indices were highest in SP. Proteobacteria, Actinobacteriota, and Acidobacteriota were dominant phyla, showing distinct distributions across stages. Beta diversity analysis (PCoA and NMDS) revealed clear separation of microbial communities. Soil organic carbon (SOC), pH, soil water content (SWC), cation exchange capacity (CEC), and bulk density (BD) significantly influenced microbial composition and distribution. Functional prediction using FAPROTAX and BugBase indicated a shift from anaerobic metabolism, nitrogen fixation, and cellulolysis in the SP to aerobic chemoheterotrophy and stress tolerance in MW. These results demonstrate that microbial communities adapt to changing soil environments during retrogressive succession, highlighting their role in ecosystem function and resilience in cold-region wetlands. Full article

The intertidal zones of estuarine wetlands serve as critical components in maintaining and promoting the sustainable development of regional ecosystems. Salt marsh vegetation, a crucial element of these zones, is experiencing significant deterioration across multiple scales due to various stressors. Despite considerable attention given to the spatial patterns and temporal evolution of salt marsh vegetation, few studies have quantitatively assessed its dynamic interactions with tidal creeks. Tidal creeks serve as primary conduits for material, energy, and information exchange between intertidal zones and adjacent ecosystems. There is a complex feedback mechanism between the development of the tidal creeks and vegetation communities. We investigated the distribution patterns and successional characteristics of salt marsh vegetation at both landscape and pixel scales, with particular emphasis on coupling dynamics with tidal creeks. Our results revealed a distinct spatial gradient in vegetation distribution across the study area. While the invasion of S. alterniflora exhibited limited direct competitive effects on S. salsa, it demonstrated significant influence on tidal creek geomorphological evolution. Notably, S. salsa exhibited pronounced sensitivity to hydrological conditions, with its growth being substantially constrained by tidal creek development and associated soil modifications. Full article

The natural regeneration of Larix gmelinii plantations plays a pivotal role in rehabilitating ecosystem services in Northeast China’s degraded forests. However, mechanistic linkages between soil aggregate nutrient fluxes and fungal community assembly remain poorly constrained. Combining space-for-time substitution with particle-size fractionation and high-throughput sequencing, this study examined successional trajectories across regeneration in Langxiang National Nature Reserve to resolve nutrient–fungal interplay during long-term forest restructuring. The results demonstrated that microaggregates (<0.25 mm) functioned as nutrient protection reservoirs, exhibiting significantly higher total carbon (TC) and nitrogen (TN) contents and greater fungal diversity (p < 0.05). Both stand regeneration stage and aggregate size significantly influenced fungal community composition and structural organization (p < 0.05). Aggregate-mediated effects predominated in upper soil horizons, where fungal dominance progressively transitioned from Mortierellomycota to Ascomycota with increasing particle size. In contrast, lower soil layers exhibited regeneration-dependent dynamics: Basidiomycota abundance declined with L. gmelinii reduction, followed by partial recovery through mycorrhizal reestablishment in Pinus koraiensis broadleaf communities. Fungal co-occurrence networks displayed peak complexity during Juglans mandshurica germination (Node 50, Edge 345), with 64.6%positive correlations, indicating the critical period for functional synergy. Basidiomycota showed significant negative correlations with nutrients and major fungal phyla (R² = 0.89). This study confirms that natural vegetation regeneration reshapes belowground processes through litter inputs and mycorrhizal symbiosis, while microaggregate management enhances soil carbon sequestration. Near-natural plantation management should incorporate broadleaf species to preserve mycorrhizal diversity and amplify ecosystem services. These findings provide an essential soil ecological theoretical basis for sustainable plantation management in Northeast China. Full article

Ectomycorrhizal (EcM) fungi are critical mediators of forest succession, yet the relative contributions of stochastic (neutral) and deterministic (niche-based) processes in shaping their communities are still poorly understood. We investigated the assembly processes in root EcM fungal communities across juvenile and adult coniferous (Abies nephrolepis, Picea jezoensis, and Pinus koraiensis) and broadleaf (Acer mono, Betula platyphylla, and Quercus mongolica) tree species in northeastern China. Employing neutral theory modeling, alpha and beta diversity metrics, and a random forest analysis, we identified patterns of EcM fungal community assembly and the specific taxa associated with developmental stages of various hosts. Neutral processes contributed to the variation in fungal communities, with adult trees showing a higher explanation power (more than 33% of variation) compared to juvenile trees (less than 7% of variation), reflecting a successional shift in assembly mechanisms. Dispersal dynamics was pronounced in juveniles but diminished with host age. Additionally, alpha diversity increased with host age and was slightly moderated by host identity, while beta diversity reflected stronger effects of host age (PERMANOVA R² = 0.057) than host identity (R² = 0.033). Host age and identity further structured communities, with distinct taxa varying between juvenile vs. adult, and coniferous vs. broadleaf hosts. Our results demonstrate that host maturity drives a transition from deterministic to stochastic assembly, modulated by tree species identity, improving our understanding of plant–fungal dynamics during forest succession. Full article

The construction and operation of dams or weirs has been demonstrated to induce alterations in riparian vegetation, a critical factor in evaluating and sustaining ecosystem health and resilience. A notable instance of this phenomenon is evidenced by the implementation of multifunctional large weirs along the major rivers of South Korea from 2008 to 2012. This study examined the successional changes in riparian vegetation caused by weir construction and operation using multi-year data from a combination of remote sensing, based on the spectra of satellite images, and field surveys on vegetation and geomorphology in the Geumgang River. The exposure duration of the sandbars and the colonization time of riparian vegetation were estimated using the normalized difference vegetation index (NDVI) and the normalized difference water index (NDWI) from multispectral satellite imagery. The study found that the duration of exposure and the vegetation successional ages varied according to the construction and operation of the weirs. The Geumgang River vegetation was classified into ten plant communities using the optimal partitioning and optimal silhouette algorithms. The in situ changes in the vegetation were traced, and the successional ages of the classified vegetations were determined. Based on these findings, three successional pathways could be proposed: The first pathway is characterized by a transition from pioneer herbaceous plants and then tall perennial grasses to willow trees on the exposed sandbar. The second pathway involves direct colonization by willow shrubs starting on the sandbar. The third pathway is marked by hydric succession, starting from aquatic vegetation in stagnant waters and lasting to willow trees. The observed vegetation succession was found to be contingent on the initial hydrogeomorphic characteristics of the environment, as well as the introduction of willow trees within the sandbar that was exposed by the operation of the weir. These findings emphasize the need for adaptive river management that integrates ecological and geomorphological processes. Controlled weir operations should mimic natural flow to support habitat diversity and vegetation succession, while targeted sediment management maintains sandbars. Long-term monitoring using field surveys and remote sensing is crucial for refining restoration efforts. A holistic approach considering hydrology, sediment dynamics, and vegetation succession is essential for sustainable river restoration. Full article

Cattle grazing and selective logging alter the functioning of an ecosystem, but their impacts on forest regeneration, particularly in relation to forest successional stages, are yet poorly understood. This study examined how these activities affect the regeneration of Nothofagus antarctica (ñire or ñirre) and N. pumilio (lenga) pure forests in Patagonia and whether these effects vary between old-growth and secondary forests. We assessed seedlings by origin (sexual, asexual) and height classes (<0.3 m, 0.3–0.6 m, >0.6 m) across 88 plots (25 × 20 m). Selective logging intensity was measured via the basal area of tree stumps, and cattle grazing pressure via dung counts. Forest regeneration, as predicted by human disturbances, forest successional stage, and tree density (parent trees), was modeled using generalized linear models. For N. antarctica, regeneration was exclusively asexual and showed a positive influence for selective logging and cattle, but negative with both interacting. In contrast, the most recent regeneration (R1) was predominantly influenced by the density of parent trees and successional stage. Conversely, N. pumilio regeneration, entirely sexual, was unaffected by cattle grazing, relying instead on parent tree density, logging intensity, and successional stage. These findings highlight the species-specific dynamics of regeneration under anthropogenic pressures. Understanding the interactions between natural and human disturbances is critical for conserving Nothofagus forests. Our results provide a basis for targeted restoration efforts and policies to mitigate degradation and promote ecosystem resilience. Full article

An epilithic algal matrix (EAM) exhibits rapid expansion, recovery capacity, and high adaptability, leading to widespread distribution in degraded coral reef habitats. However, limited research on the dynamic processes of succession hinders a comprehensive understanding of EAM formation. To examine the influence of succession processes and environmental factors on the composition of EAM microbial communities, a three-factor (time × depth × attached substrate type) crossover experiment was conducted in the Luhuitou Reef Area, Sanya, China. Microbial community compositions were analyzed through 16S rRNA gene amplicon sequencing. The community was predominantly composed of proteobacteria (61.10–92.75%), cyanobacteria (2.47–23.54%), bacteroidetes (0.86–8.49%), and firmicutes (0.14–7.76%). Successional processes were found to significantly shape the EAM-associated microbial communities in the Luhuitou Reef Area. Proteobacteria played a crucial role in biofilm formation during this process, while cyanobacteria contributed to the structural complexity of microhabitats within the EAM. A chaotic aggregation stage of approximately one month was observed before transitioning into an expansion stage, eventually stabilizing into a low-diversity community. Although the relatively smooth substrate supported high biodiversity, microorganisms displayed no preference for the three different substrates. While no significant differences in community composition were observed at small-scale depths, cyanobacteria and bacteroidetes showed positive correlations with light and temperature, respectively. The EAM-associated microbial community exhibited higher complexity in the shallower regions under increased light intensity and temperature. Given the characteristics of the microbial community succession process, continuous monitoring of changes in microbial community structure and key taxa (such as proteobacteria and cyanobacteria) during EAM formation is recommended. Full article

Close-to-nature forest management is a sustainable forest management approach aimed at achieving a balance between ecological and economic benefits. The cultivation of future crop trees in the later successional stages following the removal of competitive trees is crucial for promoting positive development trajectories of succession. Understanding the dynamic process of growth investment strategies in future crop trees facilitates the rational planning of management cycles and scopes, ultimately enhancing the quality of tree cultivation. This study was conducted in a Pinus massoniana secondary forest with close-to-nature forest management in Ningbo City, Zhejiang Province, using handheld mobile laser scanning technology to precisely reconstruct the structure of future crop trees. Over a period of 2–5 years following the initial implementation of close-to-nature forest management, 3D point cloud data were collected annually from both managed and reference (non-managed) plots. Using these multi-temporal data, we analyzed the dynamics of the investment strategies, structural growth components, and crown competition of future crop trees. A linear mixed-effect model was applied to compare the temporal variations in these indices between the managed and control plots. Our results revealed that the height-to-diameter ratio of the future crop trees gradually declined over time, while the crown-to-diameter ratio initially increased and then decreased in the managed plots. These trends were significantly different from those observed in the control plots. Additionally, the height growth rates of the future crop trees in the managed plots were consistently lower than those in the control plots, whereas the crown and diameter at breast height (DBH) growth rates were higher. Furthermore, the crown gap area between the future crop trees and their neighboring trees gradually diminished, and the crown overlap progressively increased. These results suggest that the investment in height growth, initially driven by crown competition, shifted toward crown and DBH growth following close-to-nature forest management. In the initial stage after the removal of competitive trees, future crop trees benefited from ample crown radial space and minimal crown competition. However, as the crown radial space became increasingly limited, the future crop trees shifted their growth investment toward DBH to enhance mechanical stability and achieve a balanced tree structure. Understanding these dynamic processes and the underlying mechanisms of growth investment strategies contributes to predicting future forest community development, improving forest productivity, maintaining structural diversity, and ensuring sustainable forest management. Full article

Human-induced environmental changes threaten the functional stability of natural forest ecosystems. Understanding the dominant factors influencing both functional space and stability in extremely heterogeneous environments is crucial for elucidating the stability of heterogeneous forest ecosystems. Here, 30 forest dynamic plots were established along the successional pathway in Maolan National Nature Reserve in Southwest China. By measuring 15,725 stems across 286 distinct species’ six key plant functional traits, we constructed the key plant functional traits for functional space and quantified functional redundancy (FR) and functional vulnerability (FV) to represent functional stability, and we further utilized the line model and multiple linear regression model to explore the key biotic/abiotic indicators influencing functional stability along the successional pathway of degraded karst forests. Additionally, as the successional pathway unfolded, the contribution of the six plant traits to the overall functional space increased, from 59.85% to 66.64%. These traits included specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (LT) and leaf nitrogen content (LNC), which played a crucial role in driving functional space. With the increasing species richness (FR), functional entities (p < 0.001) and FR (p < 0.001) increased, while FV (p < 0.01) decreased. The results also demonstrated a higher FR in degraded karst forests (FR > 2). However, over 51% of FEs consisted of a single species, with the majority of species clustered into a few functional entities (FEs), indicating an elevated level of FV in karst forests. Soil nutrient availability significantly influences the ecosystem’s functional stability, explaining 87% of FR variability and 100% of FV variability. Finally, the rich SR of karst forests could provide sufficient insurance effects; soil pH and available potassium (AK) enhance resilience, and exchangeable calcium (Eca), total phosphorus (TP) and total potassium (TK) indicate the resistance of functional stability in degraded karst forests. This study highlights the complex mechanisms of functional stability in extreme habitat conditions, thereby deepening our understanding of ecosystem function maintenance. Full article

The Amazon ecosystem plays a vital role in global climate regulation and biodiversity conservation but faces escalating threats from deforestation and degradation. The resulting secondary forests (SFs) provide a promising opportunity for Transformative Territorial Management, fostering restoration and enhancing conservation values. This study evaluated aboveground biomass (AGB), species diversity, forest structure, and soil properties in SFs of the Colombian Amazon along a chronosequence, from early to mature successional stages, in landscapes of mountains and of hills to identify key indicators for effective restoration management. The results show a consistent increase in AGB, species diversity, forest structure, and soil quality with forest age, though recovery patterns varied between both landscapes evaluated. Topographic differences influenced successional dynamics, with mountainous landscapes showing faster early recovery compared to the steadier, linear growth observed in hill areas. In hills, AGB at 10 years reached 12.65% of the biomass expected in a mature forest, increasing to nearly 42% by 40 years of abandonment, at a rate of 0.708 Mg C ha⁻¹ year⁻¹. In contrast, in the mountain landscape, AGB at 10 years reached approximately 8.35% of the carbon in a mature forest and increased to nearly 63.55% at 40 years. Forest age and soil properties emerged as primary drivers of AGB recovery, while diversity and forest structure played indirect but significant roles. In hill areas, soil conservation practices are critical for maintaining steady growth, whereas mountain regions benefit from assisted natural regeneration (ANR) to accelerate recovery. These findings highlight the importance of prioritizing the management of SFs as a central strategy for achieving restoration goals. Such practices are essential to enhance the ecological resilience of SFs and ensure their long-term sustainability, fostering their role as key contributors to restoration efforts and the provision of ecosystem services. Full article