Secondary Forest Succession Research Articles

Different responses of soil bacterial community to plant-plant interactions under organic-inorganic fertilizers affect seedling establishment during subalpine forest succession.

Rhizosphere bacterial community as a valuable indicator of soil quality and function, has been widespread studied. However, little knowledge is about the response of bacterial communities to plant-plant interaction and different fertilizers during secondary forest succession. We conducted a field pot experiment applying organic and inorganic fertilizers to monocultures and mixed cultures of dominant plant species from mid- to late-successional stages (Salix oritrepha, Betula albosinensis, and Picea asperata), and investigated the responses of plant growth and rhizosphere bacterial communities. Results indicated that growth rate of plant height varied among plant species, but no significant differences were observed in soil bacterial diversity and composition among plant species or inter-specific interactions under control. Compared to control, inorganic fertilizer resulted in increases in plant growth and the relative abundance of Proteobacteria, Patescibacteria, Bacteroidetes and Gemmatimonadetes, while simultaneously leading to decrease in the relative abundance of Acidobacteria, Actinobacteria, Chloroflexi, Rokubacteria and Planctomycetes. When grown with other species, the bacterial communities in the mixture resembled those of S. oritrepha in singular monoculture under inorganic fertilizer treatment, but plant growth was not affected by interspecific interaction. Unlike inorganic fertilizer, organic fertilizer significantly affected bacterial communities and increased bacterial diversity, but did not alter the effects of plant-plant interactions on bacterial communities. It was also observed that organic fertilizer facilitated later successional species' growth (P. asperata and B. albosinensis) by the mid-successional species (S. oritrepha), ultimately facilitating secondary forest succession. In addition, plants at different successional stages harbor specific bacterial communities to affect their growth, and the bacterial communities contributed more than soil properties to the variations in the plant growth of S. oritrepha and P. asperata though the bacterial communities were regulated by soil factors. This finding highlights the significance of the rhizosphere bacteria on plant growth and plant community succession. It also emphasize the importance of considering both plant-plant interactions and diverse fertilizer types in forest restoration efforts and provide valuable insights into optimizing agronomic practices for secondary forest succession.

Leaf trait networks shift toward high modularity during the succession of a subtropical forest, in southwest China

During the process of forest succession, coexisting plant species fulfill diverse functions by modifying the interrelationships among functional traits. Examining the interrelationships of functional traits across multiple dimensions would enable a comprehensive understanding of the plants’ adaptive strategies during forest succession. Plant trait networks (PTNs) comprehensively capture and visualize these intricate relationships among functional traits. Nonetheless, the changes in PTNs during forest secondary succession remain unclear. In this study, we measured 24 functional traits related to leaf resource acquisition, photosynthesis, hydraulics, and physical defense across tree species at three successional stages: young forest (YF), intermediate forest (IF), and old-growth forest (OF) in the Ailao Mountains, Southwest China. We established leaf trait networks (LTNs) to investigate the interrelationships among functional traits during forest succession. Our results revealed a decrease in the Edge Density decreased and an increase in the Modularity as succession advanced. In the YF stage, leaf nitrogen, photosynthetic rate, and force to punch were the hub traits; whereas, canopy exposure and leaf dry mass were highly connected traits in the IF and OF stages, respectively. The connectivity of highly connected traits was related to the plant’s life-history strategies and environmental adaptations at different successional stages. In terms of the importance of the four trait dimensions, resource acquisition and photosynthetic traits consistently demonstrated strong connectivity within LTNs throughout the succession. We concluded that co-occurring tree species adapted to the changing environmental conditions by adjusting trait modules through alternative strategies during secondary succession. Specifically, resource acquisition and trait coordination were more advantageous in the YF stage, while higher modularity offered greater opportunities for niche differentiation in the OF stage. This study provides new insights into exploring the mechanisms of forest succession through the analysis of trait correlation networks.

Shifts in fungal community diversity and potential function under natural forest succession and planted forest restoration in the Kunyu Mountains, East China.

Soil fungi participate in various ecosystem processes and are important factors driving the restoration of degraded forests. However, little is known about the changes in fungal diversity and potential functions under the development of different vegetation types during natural (secondary forest succession) and anthropogenic (reforestation) forest restoration. In this study, we selected typical forest succession sequences (including Pinus densiflora Siebold & Zucc., pine-broadleaf mixed forest of P. densiflora and Quercus acutissima Carruth., and Q. acutissima), as well as natural secondary deciduous broadleaved mixed forests and planted forests of Robinia pseudoacacia on Kunyu Mountain for analysis. We used ITS rRNA gene sequencing to characterize fungal communities and used the FUNGuild database to predict fungal functional groups. The results showed that forest succession affected fungal β-diversity, but not the α-diversity. There was a significant increase in Basidiomycota and a decrease in Ascomycota in the later successional stage, accompanied by an increase in the functional groups of ectomycorrhizal fungi (ECM). Conversely, planted forests exhibited decreased fungal α-diversity and altered community compositions, characterized by fewer Basidiomycota and more Ascomycota and Mucoromycota. Planted forests led to a decrease in the relative abundances of ECM and an increase in animal pathogens. The TK content was the major factor explaining the distinction in fungal communities among the three successional stages, whereas pH, AP, and NH4 + were the major factors explaining community variations between natural and planted forests. Changes in vegetation types significantly affected the diversity and functional groups of soil fungal communities during forest succession and reforestation, providing key insights for forest ecosystem management in temperate forests.

Using the Forest Maturity Index to model understory regeneration of post-agricultural forest in the NE Carpathians

The regeneration dynamics of understory vegetation in recent forests, arising from extensive agricultural land abandonment, is closely related to soil properties and proximity to ancient forests. However, the role of topography in shaping this regeneration process, especially in mountainous regions, remains unclear.This study addresses this gap by investigating the regeneration rate of understory vegetation in mountainous recent forests within the NE Carpathians, a region profoundly shaped by large-scale population displacements in the 1940s, leading to widespread agricultural land abandonment and the subsequent development of new forests.We quantified the understory regeneration rate of recent forests through extensive phytosociological relevé surveys conducted in one vegetation season. Data were collected from 194 randomly selected plots of recent forests and 100 plots of ancient forests, each exhibiting diverse topographic characteristics. By calculating the Forest Maturity Index based on ancient forest species and employing a parametrized multiple regression model, we identified key factors influencing the understory regeneration process. We further used the obtained regression formula to model the forest regeneration rate across the entire study area (40,975 ha).Proximity to ancient forests positively influenced understory regeneration. Elevation and slope also emerged as significant determinants, with the understory regeneration rate decreasing with elevation and increasing with slope steepness. Furthermore, a higher cover of pine in the tree stand had a suppressive effect. The above-mentioned dependencies resulted in substantial variations in the modeled understory regeneration of post-agricultural forests.The utilization of the Forest Maturity Index offers invaluable insights into identifying and subsequently safeguarding well-regenerated forests. Given the prevalence of forest secondary succession in various regions, this index emerges as a key indicator for future assessments and management strategies.

Trees adjust nutrient acquisition strategies across tropical forest secondary succession.

Nutrient limitation may constrain the ability of recovering and mature tropical forests to serve as a carbon sink. However, it is unclear to what extent trees can utilize nutrient acquisition strategies - especially root phosphatase enzymes and mycorrhizal symbioses - to overcome low nutrient availability across secondary succession. Using a large-scale, full factorial nitrogen and phosphorus fertilization experiment of 76 plots along a secondary successional gradient in lowland wet tropical forests of Panama, we tested the extent to which root phosphatase enzyme activity and mycorrhizal colonization are flexible, and if investment shifts over succession, reflective of changing nutrient limitation. We also conducted a meta-analysis to test how tropical trees adjust these strategies in response to nutrient additions and across succession. We find that tropical trees are dynamic, adjusting investment in strategies - particularly root phosphatase - in response to changing nutrient conditions through succession. These changes reflect a shift from strong nitrogen to weak phosphorus limitation over succession. Our meta-analysis findings were consistent with our field study; we found more predictable responses of root phosphatase than mycorrhizal colonization to nutrient availability. Our findings suggest that nutrient acquisition strategies respond to nutrient availability and demand in tropical forests, likely critical for alleviating nutrient limitation.

Light competition drives species replacement during secondary tropical forest succession

Light competition is thought to drive successional shifts in species dominance in closed vegetations, but few studies have assessed this for species-rich and vertically structured tropical forests. We analyzed how light competition drives species replacement during succession, and how cross-species variation in light competition strategies is determined by underlying species traits. To do so, we used chronosequence approach in which we compared 14 Mexican tropical secondary rainforest stands that differ in age (8–32 year-old). For each tree, height and stem diameter were monitored for 2 years to calculate relative biomass growth rate (RGR, the aboveground biomass gain per unit aboveground tree biomass per year). For each stand, 3D light profiles were measured to estimate individuals’ light interception to calculate light interception efficiency (LIE, intercepted light per unit biomass per year) and light use efficiency (LUE, biomass growth per intercepted light). Throughout succession, species with higher RGR attained higher changes in species dominance and thus increased their dominance over time. Both light competition strategies (LIE and LUE) increased RGR. In early succession, a high LIE and its associated traits (large crown leaf mass and low wood density) are more important for RGR. During succession, forest structure builds up, leading to lower understory light levels. In later succession, a high LUE and its associated traits (high wood density and leaf mass per area) become more important for RGR. Therefore, successional changes in relative importance of light competition strategies drive shifts in species dominance during tropical rainforest succession.

Soil bacterial community structure and co‐occurrence networks in response to the succession of secondary forests in subtropical regions

AbstractA large amount of secondary successional vegetation (subtropical evergreen broadleaved forests) has formed after the extensive deforestation and cultivation of coniferous forests in Wuyi Mountain, Southeast China. However, we lack a detailed understanding of the dynamic changes in microbial community structure and its co‐occurrence network during succession. The features that are responsible for alterations in the soil bacterial community remain poorly defined. Therefore, we compared the soil physicochemical properties, enzyme activities, and bacterial diversity among three different forests (a coniferous forest [CF], early stage of succession; a mixed conifer‐broadleaf forest [CBMF], middle stage of succession; an evergreen broadleaf forest [EBF]; late stage of succession). Results indicated that the contents of soil organic carbon and microbial biomass carbon (MBC) in CBMF were higher compared with those in CF. The alpha diversity indices were the highest in CBMF. Functional annotation of prokaryotic taxa predicted the relative abundances of chemoheterotrophy and aerobic chemoheterotrophy were lower in CF than in the other two forests. Bacterial network topology was affected by forest succession, with CBMF having more complex bacterial networks. Mantel's test indicated the soil nitrate nitrogen content (P = 0.03) was the most important property that shaped the bacterial community composition, bacterial diversity was influenced by soil pH (P = 0.026), and the contents of available phosphorus (P = 0.04) and MBC (P = 0.022) during the succession process. In conclusion, the succession of secondary forests promoted soil nutrient accumulation and improved bacterial diversity and network complexity.

Functional richness mediates landscape and management effects on tree biomass and soil fertility during secondary forest succession

Secondary forests can play a critical role in conserving plant biodiversity and sequestering carbon. However, intensive past management, fragmentation, and initial soil fertility can hinder forest recovery during secondary succession, especially in terms of tree species selection. In turn, tree species selection can negatively impact soil fertility recovery and may slow down the succession process, but the direct and indirect effects between these factors remain unclear. To assess the complex interactions among landscape, previous management, soil and vegetation, 27 secondary forests of varying ages, previously used for eucalyptus plantations, located in diverse landscape configurations within the Atlantic Forest biome, were examined. Key variables, such as planting frequency, cutting frequency, forest cover in the landscape, patch isolation between fragments, functional richness, tree aboveground biomass (AGB), soil sum of bases, soil organic matter, and soil phosphorus concentration were used to construct a structural equation model to evaluate the direct and indirect effects of landscape and previous management on forest development. Cutting frequency and patch isolation had a negative direct effect on functional richness. Additionally, a strong positive direct effect of functional diversity on aboveground biomass and soil sum of bases was found. Thus, cutting frequency and patch isolation had negative indirect effects on biomass and soil sum of bases (a proxy for soil fertility), mediated by functional richness. These findings underscore the significance of integrating plant functional diversity into restoration strategies to preserve ecosystem functioning and efficiently recover biodiversity, tree biomass, and soil fertility in secondary forests.

Carbon Sequestration Dynamics in Peri-Urban Forests: Comparing Secondary Succession and Mature Stands under Varied Forest Management Practices

This study examines the impact of silvicultural and land-use management practices on carbon sequestration in peri-urban forest ecosystems, with a particular focus on human-induced carbon dynamics. The study area’s complex profile spans from a compact native forest to varying degrees of fragmentation. This included areas undergoing secondary succession forest without silvicultural interventions (No-SI) alongside sites subjected to high-intensity (High-SI) and low-intensity silvicultural interventions (Low-SI). The research assessed carbon stocks and sequestration in different carbon pools (living biomass, dead organic matter and soil) using field data, allometric equations and laboratory analysis. Findings reveal a significant correlation between the intensity of anthropogenic interventions and variations in carbon stocks. The CASMOFOR model facilitated the reconstruction of carbon stock and carbon-stock change dynamics over four decades (1980–2022), showing disparities in carbon storage capabilities linked to the structural characteristics of the sites. The Low-SI site had the highest carbon stock in all carbon pools (378 tonnes C ha−1), which is more than double compared to High-SI (161 tonnes C ha−1) or No-SI sites (134 tonnes C ha−1). However, the secondary succession forest (No-SI) demonstrated the highest annual carbon stock change (4.4 tonnes C ha−1 year−1), two times higher than the Low-SI mature stand (2.2 tonnes C ha−1 year−1), emphasising the resilience of forest ecosystems to recover and sustain carbon sequestration capacities after harvesting if forest land use remains unchanged. The study underscores the significant importance of anthropogenic interventions on carbon dynamics, especially for living tree biomass, which has consequences in enhancing carbon sequestration and contributing to emission reduction targets.

Carbon，nitrogen and phosphorus stoichiometry in soil and dominant trees’ stem at different stages of subtropical secondary forest succession

Carbon，nitrogen and phosphorus stoichiometry in soil and dominant trees’ stem at different stages of subtropical secondary forest succession

Disentangling mechanisms that mediate soil fungal α and β diversity during forest secondary succession

Understanding the mechanisms controlling community diversity is a central, topic in ecology, particularly in microbial ecology. Although species pools and local assembly processes are believed to play non‐negligible roles in shaping the within‐community (α) and among‐community (β) diversity of microbial communities, their relative importance as succession progresses remains elusive. Moreover, the roles of both mechanisms on diversity might be strikingly different depending on whether saturation is considered or not, yet this issue is far less appreciated. To investigate the mechanisms underlying soil fungal α and β diversity during secondary succession, soil samples were collected from six different successional chronosequences including 293 plots across different climatic zones. We found that in all chronosequences, increases in α diversity tracked increases in species pool size, showing a linear unsaturated relationship, despite β diversity not always co‐varied with species pool size. After correcting for differences in species pools, environmental selection appeared to explain variation in β diversity rather than variation in α diversity. Further piecewise structural equation modeling demonstrated that the species pool was more important in α diversity change than environmental selection in most of the cases, whereas the importance of heterogeneous selection outweighed species pool in shaping β diversity. Overall, these findings represent one of the first to demonstrate that most local fungal communities might be unsaturated, where the relative importance of species pool and environmental selection for variations in α and β diversity during secondary succession differs markedly. Considering the mechanisms controlling diversity will be distinctly different under unsaturation or saturation, we set up an extended conceptual model combined with saturation theory to broaden the perspective to comprehensively understand mechanisms causing biodiversity change during secondary succession in unsaturated/saturated communities, intending to enhance our ability to predict soil fungal diversity in the future.

Changing Dynamic of Tree Species Composition and Diversity: A Case Study of Secondary Forests in Northern China in Response to Climate Change

Climate warming is believed to have irreversible effects on biodiversity and ecosystem functions. Secondary forests are non-negligible ecosystems in northern China that have attracted much attention because of their instability and sensitivity to global change. However, there is no consensus on the impact of warming on secondary forest succession. In this study, we explored the response of tree species diversity to climate warming in northern secondary forests in China using a series of field surveys combined with annual meteorological data from 2015 to 2021. Our results indicate that the temperature in the study area increased in spring and autumn, while the precipitation increased in spring, summer, and autumn from 2015 to 2021. Changes in species composition in the study area and climate warming were significant in the northern region of China. The importance values of many broadleaf tree species increased, whereas those of local coniferous and broadleaf tree species decreased. The Shannon–Wiener, Simpson, and Margalef indices for the pure forest were significantly lower than those for the broadleaf mixed forest and the conifer–broadleaf mixed forest (p < 0.05) in 2015 and 2021. The highest value for the Pielou index was in the conifer–broadleaf mixed forest (p < 0.05), whereas it was not significantly different between the pure forest and broadleaf mixed forest in 2021. Surprisingly, the secondary broadleaf mixed forest in northern China showed an unfavorable degradation trend under the influence of climate change, just the same as the secondary pure forest. Our work provides an experimental data source for research on secondary forests under various climate change scenarios and is an important reference for predicting and dealing with the impact of global climate change on the adaptive management and protection of secondary ecosystems.

Rapid recovery of ant-mediated seed dispersal service along secondary succession in a Caatinga dry forest

Global expansion of secondary forests results from old-growth forest conversion to agriculture and livestock fields, followed by abandonment. Dry forests heavily rely on resprouting for rapid biomass recovery, but some species depend on seed dispersers. Ants are important seed dispersers in dry forests, as they can transport seeds over long distances, help species join the soil seed bank, and promote seed germination and seedling recruitment. We investigated seed-dispersing ant community, ant-seed interactions, and seed removal rates and distances along a Caatinga dry forest secondary succession using forest stands (8–54 years) after slash-and-burn agriculture and old-growth forest stands. We observed 796 interactions with 29 ant species and four plant species. About 26.51% were removals by 12 ant species, notably Dinoponera quadriceps and Ectatomma muticum, dispersing seeds up to 15 m. Only 14% of removed seeds reached nests while the rest were lost along foraging trails. Ant abundance of seed-dispersing ant community increased significantly with forest aboveground biomass, and both ant abundance and richness were significantly higher in secondary forest stands. Ant-seed interactions increased with biomass, being higher in old-growth forests. However, ant community composition, removal rates, and dispersal distances remained consistent across biomass and forest types. These findings may suggest that ant-mediated seed dispersal service quickly recovers during secondary succession, with implications for the dynamics of forest regeneration, given that ant-mediated seed dispersal is a prevalent and widespread phenomenon in the Caatinga dry forest.

Changes in species diversity and influencing factors in secondary forest succession in northern Da Hinggan Mountains

Changes in species diversity and influencing factors in secondary forest succession in northern Da Hinggan Mountains

The Changes, Aggregation Processes, and Driving Factors for Soil Fungal Communities during Tropical Forest Restoration.

Soil fungal communities play crucial roles in mediating the functional associations between above- and belowground components during forest restoration. Forest restoration shapes the alterations in plant and soil environments, which exerts a crucial effect on soil fungal assemblages. However, the changes, assembly processes, and driving factors of soil fungi communities during tropical forest restoration are still uncertain. We used Illumina high-throughput sequencing to identify the changes of soil fungal communities across a tropical secondary forest succession chronosequence (i.e., 12-, 42-, and 53-yr stages) in Xishuangbanna. During forest restoration, the dominant taxa of soil fungi communities shifted from r- to K-strategists. The relative abundance of Ascomycota (r-strategists) decreased by 10.0% and that of Basidiomycota (K-strategists) increased by 4.9% at the 53-yr restoration stage compared with the 12-yr stage. From the 12-yr to 53-yr stage, the operational taxonomic unit (OTU), abundance-based coverage estimator (ACE), Chao1, and Shannon index of fungal communities declined by 14.5-57.4%. Although the stochastic processes were relatively important in determining fungal assemblages at the late stage, the fungal community assembly was dominated by deterministic processes rather than stochastic processes. The shifts in soil properties resulting from tropical forest restoration exerted significant effects on fungal composition and diversity. The positive effects of microbial biomass carbon, readily oxidizable carbon, and soil water content explained 11.5%, 9.6%, and 9.1% of the variations in fungal community composition, respectively. In contrast, microbial biomass carbon (40.0%), readily oxidizable carbon (14.0%), and total nitrogen (13.6%) negatively contributed to the variations in fungal community diversity. Our data suggested that the changes in fungal composition and diversity during tropical forest restoration were primarily mediated by the positive or negative impacts of soil carbon and nitrogen pools.

Species pool, local assembly processes: Disentangling the mechanisms determining bacterial α- and β-diversity during forest secondary succession.

Across ecology, and particularly within microbial ecology, there is limited understanding how the generation and maintenance of diversity. Although recent work has shown that both local assembly processes and species pools are important in structuring microbial communities, the relative contributions of these mechanisms remain an important question. Moreover, the roles of local assembly processes and species pools are drastically different when explicitly considering the potential for saturation or unsaturation, yet this issue is rarely addressed. Thus, we established a conceptual model that incorporated saturation theory into the microbiological domain to advance the understanding of mechanisms controlling soil bacterial diversity during forest secondary succession. Conceptual model hypotheses were tested by coupling soil bacterial diversity, local assembly processes and species pools using six different forest successional chronosequences distributed across multiple climate zones. Consistent with the unsaturated case proposed in our conceptual framework, we found that species pool consistently affected α-diversity, even while local assembly processes on local richness operate. In contrast, the effects of species pool on β-diversity disappeared once local assembly processes were taken into account, and changes in environmental conditions during secondary succession led to shifts in β-diversity through mediation of the strength of heterogeneous selection. Overall, this study represents one of the first to demonstrate that most local bacterial communities might be unsaturated, where the effect of species pool on α-diversity is robust to the consideration of multiple environmental influences, but β-diversity is constrained by environmental selection.

Assessing Spatio-Temporal Change and Dynamics of Forest Ecosystem Succession Using Patch Analysis

Aim of study: This study focuses on creating a secondary forest succession (SFS) map between 1972 and 2014 according to the Clementsian theory based on land cover, assessing the spatio-temporal pattern of forest succession change, and determining the factors affecting the forest ecosystem.
 Area of study: This study was conducted at the Çermik Forest Enterprise (FE) in Diyarbakır city, located in the Southeastern Anatolia Region of Türkiye.
 Material and methods: Clementsian theory, Remote Sensing (RS), and Geographical Information System (GIS) were used to generate the SFS map. Patch Analyst 4.0 was used to determine changes in spatiotemporal patterns with landscape indices.
 Main results: The total forested area increased from 32405.1 ha (13% of the study area) in 1972 to 45054.7 ha (18% of the study area) in 2014, with a net increase of 12649.6 ha. It was determined that the progressive succession area was 87736.7 ha, the regressive succession area was 39216.5 ha, and the unchanged succession area was approximately 129989.6 ha. The number of patches increased over a 42-year period.
 Research highlights: The forest ecosystem was more fragmented, with patches becoming more irregular, complex, and edgy

Rhizocompartmental microbiomes of arrow bamboo (Fargesia nitida) and their relation to soil properties in Subalpine Coniferous Forests.

Arrow bamboo (Fargesia nitida) is a pioneer plant in secondary forest succession in the Sichuan Province mountains. To comprehensively investigate the microbial communities and their functional variations in different rhizocompartments (root endosphere, rhizosphere, and root zone) of arrow bamboo (Fargesia nitida), a high-throughput metagenomic study was conducted in the present study. The results showed that the abundances of the dominant bacterial phyla Proteobacteria and Actinobacteria in the bamboo root endosphere were significantly lower than those in the rhizosphere and root zones. In contrast, the dominant fungal phyla, Ascomycota and Basidiomycota, showed the opposite tendency. Lower microbial diversity, different taxonomic composition and functional profiles, and a greater abundance of genes involved in nitrogen fixation (nifB), cellulose degradation (beta-glucosidase), and cellobiose transport (cellulose 1, 4-beta-cellobiosidase) were found in the bamboo root endosphere than in the other rhizocompartments. Greater soil total carbon, total nitrogen, NH4+-N, microbial biomass carbon, and greater activities of invertase and urease were found in the bamboo root zone than in the adjacent soil (spruce root zone). In contrast, the soil microbial community and functional profiles were similar. At the phylum level, invertase was significantly related to 31 microbial taxa, and the effect of NH4+-N on the microbial community composition was greater than that of NO3--N. The soil physicochemical properties and enzyme activities were significantly correlated with microbial function. These results indicate that the root endosphere microbiomes of arrow bamboo were strongly selected by the host plant, which caused changes in the soil nutrient properties in the subalpine coniferous forest.

Effects of large mammal exclusion on seedling communities depend on plant species traits and landscape protection in human‐modified Costa Rican forests

Abstract Large terrestrial herbivorous mammals (LTH‐mammals) influence plant community structure by affecting seedling establishment in mature tropical forests. Many of these LTH‐mammals frequent secondary forests, but their effects on seedling establishment in them are understudied, hindering our understanding of how LTH‐mammals influence forest regeneration in human‐modified landscapes. We tested the hypothesis that the strength of LTH‐mammals' effects on seedling establishment depends on landscape protection, forest successional stage and plant species' traits using a manipulative field experiment in six 1‐ha sites with varying successional age and landscape protection. In each site, we established 40 seedling plot‐pairs, with one plot excluding LTH‐mammals and one not, and monitored seedlings of 116 woody species for 26 months. We found significant effects of LTH‐mammal exclusion on seedling survival contingent upon the protection of forests at the landscape level and forest stage. After 26 months, survival differences between LTH‐mammal exclusion and non‐exclusion treatments were greater in protected than unprotected landscapes. Additionally, plant species' traits were related to the LTH‐mammals' differential effects, as LTH‐mammals reduced the survival of seedlings of larger‐seeded species the most. Overall, LTH‐mammals' effects translated into significant shifts in community composition as seedling communities inside and outside the exclosures diverged. Moreover, lower density and higher species diversity were found as early as 12 and 18 months outside than inside exclosures. Synthesis and applications. Insight into the interactions between LTH‐mammals and seedling communities in forest regeneration can be instrumental in planning effective restoration efforts. We highlight the importance of landscape protection in seedling survival and the role of LTH‐mammals in promoting seedling diversity in mature forests but also in secondary successional forests. The findings suggest that conservation efforts and possibly trophic rewilding can be important approaches for preserving diversity and influencing the trajectory of secondary tropical forest succession. However, we also caution that an overabundance of LTH‐mammals may adversely impact the pace of forest succession due to their preference for large‐seeded species. Therefore, a comprehensive wildlife management plan is indispensable. Additionally, longer term studies on LTH‐mammals are necessary to understand the effects of temporal fluctuations that are undetected in short‐term studies.

Litterfall and element fluxes in secondary successional forests of South Korea

Determining litterfall and corresponding element fluxes is valuable in understanding productivity and biogeochemical cycling in floristically distinct secondary successional zones. Secondary-growth forests form a major portion of the cool-temperate forests of South Korea following decades of severe disturbance and intensive rehabilitation efforts. This study monitored the total and fraction-specific litterfall mass, element flux, and nutrient use efficiency patterns of a secondary-growth broadleaf deciduous forest (hereafter, BDFA) and compared these values in forests with contrasting sub-canopy compositions (BDFB) and with coniferous evergreen forests (CEF). Mean annual total litterfall mass was uniform across stands at a range of 871.5 g m−2 yr−1 to 990.2 g m−2 yr−1. Litterfall mass of seed, bark, and miscellaneous fractions varied per stand (p < 0.05 for seed; p < 0.01 for bark and miscellaneous). A pronounced unimodal litterfall peak was detected for all stands, with total litterfall responding positively to relative humidity but negatively to windspeed and solar radiation. Coniferous evergreen litter contained higher C but lower macronutrients relative to broadleaf deciduous litter. Macronutrient fluxes ranged from 156.2 to 183.9 kg ha−1 yr−1, with broadleaf stands having significantly higher K and Ca rates. Macronutrients were returned in all stands in the order of N > Ca > K > Mg > P, whereas NUE followed a reverse sequence. NUE in CEF was higher than BDFA and BDFB for all macronutrients, reflecting the distinct biomass allocation and nutrient utilization strategies between conifers and broadleaves. In temperate secondary-growth forests, nutrient cycling via litterfall is substantiated primarily by litterfall quantity and secondarily by litter element concentration. Our findings have important implications for elucidating forest litter ecology and improving sustainable management practices in secondary successional forests.