Stages Of Secondary Succession Research Articles

Changes in nitrogen and phosphorus availability driven by secondary succession in temperate forests shape soil fungal communities and function.

The soil fungal community plays an important role in forest ecosystems and is crucially influenced by forest secondary succession. However, the driving factors of fungal community and function during temperate forest succession and their potential impact on succession processes remain poorly understood. In this study, we investigated the dynamics of the soil fungal community in three temperate forest secondary successional stages (shrublands, coniferous forests, and deciduous broad-leaved forests) using high-throughput DNA sequencing coupled with functional prediction via the FUNGuild database. We found that fungal community richness, α-diversity, and evenness decreased significantly during the succession process. Soil available phosphorus and nitrate nitrogen decreased significantly after initial succession occurred, and redundancy analysis showed that both were significant predictors of soil fungal community structure. Among functional groups, fungal saprotrophs and pathotrophs represented by plant pathogens were significantly enriched in the early-successional stage, while fungal symbiotrophs represented by ectomycorrhiza were significantly increased in the late-successional stage. The abundance of both saprotroph and pathotroph fungal guilds was positively correlated with soil nitrate nitrogen and available phosphorus content. Ectomycorrhizal fungi were negatively correlated with nitrate nitrogen and available phosphorus content and positively correlated with ammonium nitrogen content. These results indicate that the dynamics of fungal community and function reflected the changes in nitrogen and phosphorus availability caused by the secondary succession in temperate forests. The fungal plant pathogen accumulated in the early-successional stage and ectomycorrhizal fungi accumulated in the late-successional stage may have a potential role in promoting forest succession. These findings contribute to a better understanding of the response of soil fungal communities to secondary forest succession and highlight the importance of fungal communities during the successional process.

Effect of plant-soil feedback on soil microbial co-occurrence network depends on the stage of secondary succession

Co-occurrence networks of soil microbial community are used to describe co-occurrence relationships in microbial communities, which can better understand the structure, function, and interaction patterns of microbial communities at different succession stages, but how co-occurrence networks within microbial communities respond to the effects exerted by plants come from different successional stages is unknown. Changes in the co-occurrence network of soil fungal and bacterial communities after plant species grown under monoculture were analyzed with a greenhouse experiment using the rhizosphere soils collected from early-, mid-, and late-successional species in the field. Results showed that compared with the soil microbial communities of plants grew in their own soil conditions, significant changes were observed in the Chao1 and ACE richness of the fungal community and Shannon and Simpson indices of the bacterial community after the growth of plants in other stages of succession; the relative abundance of the bacterial communities were mainly affected rather than the fungal communities at the phylum level. The late-successional species (or mid-successional species) mainly increased the graph density and average clustering coefficient (network complexity) of the fungal and bacterial communities in soil conditioned by the early- and mid-successional species (or early-successional species). Soil water-soluble nitrogen and phosphorus were the main soil factor affecting the relative abundance of the fungal and bacterial communities in species succession. The pre-successional species may be replaced directly by the subsequent plant species in a succession sequence given the network complexity of soil microbial communities.

The contrasting responses of abundant and rare microbial community structures and co-occurrence networks to secondary forest succession in the subalpine region.

Knowledge of variations in abundant and rare soil microbial communities and interactions during secondary forest succession is lacking. Soil samples were gathered from different secondary successional stages (grassland, shrubland, and secondary forest) to study the responses of abundant and rare bacterial and fungal communities, interactions and driving factors to secondary forest succession by Illumina sequencing of the 16S and ITS rRNA genes. The results showed that the α-diversities (Shannon index) of abundant bacteria and fungi revealed no significant changes during secondary forest succession, but increased significantly for rare bacteria. The abundant and rare bacterial and fungal β-diversities changed significantly during secondary forest succession. Network analysis showed no obvious changes in the topological properties (nodes, links, and average degree) of abundant microbial networks during secondary forest succession. In contrast, these properties of the rare microbial networks in the secondary forest were higher than those in the grassland and shrubland, indicating that rare microbial networks are more responsive to secondary forest succession than abundant microorganisms. Additionally, rare microbial networks revealed more microbial interactions and greater network complexity than abundant microbial networks due to their higher numbers of nodes and links. The keystone species differed between the abundant and rare microbial networks and consisted of 1 and 48 keystone taxa in the abundant and rare microbial networks, respectively. Soil TP was the most important influencing factor of abundant and rare bacterial communities. Successional stages and plant richness had the most important influences on abundant and rare fungal communities, respectively. C:P, SM and N:P were mainly related to abundant and rare microbial network topological properties. Our study indicates that abundant and rare microbial communities, interactions and driving factors respond differently to secondary forest succession.

Tree diversity in riparian forests immersed in a pasture with Urochloa decumbens (Stapf) R.D. Webster (Poaceae) grass under domain of the Atlantic Forest, Brazil

The riparian vegetation along water courses and the health of the river’s basin, regarding the aquatic and terrestrial ecosystems associated with them, are widely discussed in literature. However, the maintenance of the services and the conservation role that riparian forests provide to flora and fauna may be affected by the regional matrix that surrounds the water course and by the length and composition of the riparian vegetation associated with them. This study aimed to evaluate the relationships among the grass cover and arboreal species diversity in three watercourses surrounded by a pasture dominated with the alien grass Uroclhoa decumbens (Stapf) R.D. Webster (former Brachiaria decumbens). Two hypotheses were tested: (i) watercourses with larger riparian forest width present higher richness and abundance of native and zoochoric tree species and those associated to late succession stages, and (ii) watercourses with larger riparian forest width present a lower grass cover on their interior. The study was conducted under domain of Semideciduous Seasonal Forest, belonging to the Atlantic Forest biome, municipality of Londrina, Paraná State, south Brazil. The regional climate is Köppen’s Cfa humid subtropical. The soil is classified as a mosaic of eutroferric red nitosols and lithosols. The studied sites mostly comprise pasture with U. decumbens alien grass and small patches of woody vegetation amidst an open pasture dominated by species attributed to the first’s stages of secondary succession. The studied site is immersed in Cambé’s River watershed and contain three watercourses, Cristal River, tributary to São Lourenço River, that, in turn, is tributary to Cambé River. All watercourses are classified as small rivers (Brazilian Forestry Code, federal law: n. 12.651/2012), with length inferior to 10 m between both riversides. The riparian vegetation shares similar characteristics and structure, encompassing woody vegetation with pioneer trees species and high canopy openness. All riparian forests are immersed in pastures with U. decumbens grass. Transects of 200 meters long, measuring one meter wide from the line on both sides of the transect, and one square plot (25 m2) were allocated on the interior of each riparian forest. Transects were evaluated as arboreal species richness and the length of the riparian forest strip. In each plot, the arboreal vegetation was inventoried as species richness, abundance and density, and the U. decumbens cover was measured. The riparian forest width was arranged in two classes, forests with width ≤ 5 m or ≥ 10 m. The studied forests were compared as richness, abundance, density, and grass cover. The correlations among the riparian vegetation with the forest width and grass coverage (%) were evaluated. Species richness, abundance and density did not differ among the watercourses. However, species abundance and density presented positive correlations with the riparian forest width, indicating that the larger is the riparian vegetation, the higher is the species density. Grass cover presents a strong negative correlation with the riparian forest width, indicating that narrow strips of woody vegetation present higher grass cover. A high positive correlation was observed with riparian strip width and native trees, suggesting that native woody species establishment is limited by the riparian strip width and that those rustic trees species are more capable to colonize these environments. Also, the correlation found with species that present abiotic syndromes and pioneer species indicates that trees that can colonize open areas are more suitable to establish on narrow strips of vegetation amidst a pasture. The relationships observed with zoochoric trees suggests that the fauna that visits these forests are tolerant to open areas and visit these areas independently of their vegetation width. The larger riparian forests present lower grass cover and these can be related to shadow micro-sites that reduce the luminosity which can affect the permanence potential of the dominance of U. decumbens. In this way, the data suggests that few plants can establish in these pasture landscape, and those more rustic trees which are able to establish under open areas, high grass cover and canopy openness, and that re-sprout after a fire, became more dominant. For these watercourses, with narrow riparian vegetation strips surrounded by an U. decumbens pasture, the high grass cover can restrict and plant diversity, acting on the course and velocity of secondary succession in these areas.

Alterations of ecosystem nitrogen status following agricultural land abandonment in the Karst Critical Zone Observatory (KCZO), Southwest China.

Secondary succession after agricultural land abandonment generally affects nitrogen (N) cycle processes and ecosystem N status. However, changes in soil N availability and NO3 - loss potential following secondary succession are not well understood in karst ecosystems. In the Karst Critical Zone Observatory (KCZO) of Southwest China, croplands, shrub-grass lands, and secondary forest lands were selected to represent the three stages of secondary succession after agricultural land abandonment by using a space-for-time substitution approach. The contents and 15N natural abundance (δ 15N) of leaves, soils, and different-sized aggregates at the three stages of secondary succession were analyzed. The δ 15N compositions of soil organic nitrogen (SON) in aggregates and soil to plant 15N enrichment factor (EF = δ 15Nleaf -δ 15Nsoil), combined with soil inorganic N contents and δ 15N compositions were used to indicate the alterations of soil N availability and NO3 -loss potential following secondary succession. Leaf N content and SON content significantly increased following secondary succession, indicating N accumulation in the soil and plant. The δ 15N values of SON also significantly decreased, mainly affected by plant δ 15N composition and N mineralization. SON content in macro-aggregates and soil NH4 + content significantly increased while δ 15N values of NH4 + decreased, implying increases in SON stabilization and improved soil N availability following secondary succession. Leaf δ 15N values, the EF values, and the (NO3 --N)/(NH4 +-N) ratio gradually decreased, indicating reduced NO3 - loss following secondary succession. Soil N availability improves and NO3 - leaching loss reduces following secondary succession after agricultural land abandonment in the KCZO.

Effects of secondary forest succession on the richness and composition of frog species in humid tropical forest

ABSTRACT Our aim was to evaluate whether the richness and composition of anurans responded to the time of forest regeneration via secondary succession. We sampled the anuran community in a mosaic of areas at three different stages of secondary succession in the Atlantic Forest, southern Brazil. The anurans were collected from nine lentic ponds and from their margins up to a 50 m radius. The late secondary forest sheltered the higher species richness, followed by the primary forest. The spatial variation in species richness was related to the forest succession stage and predominance of arboreal vegetation on the pond edge. The species composition changed throughout the succession stages, regardless of the distance among areas. Along the gradient of forest succession, environmental changes have driven species distribution, limiting the occurrence of forest species and favoring the colonization of areas at the early succession stage by opportunist species. We could observe that the secondary forest succession was a determining factor in the anuran community structure, and with the advancement of the secondary succession, both richness and composition were partly restored. Thus, the conservation of secondary forests might be an efficient strategy to preserve the biodiversity in areas of the Atlantic Forest.

BIOMASS AND NUTRIENTS IN THE FOREST-FLOOR LITTER OF SECOND-GROWTH BRAZILIAN ATLANTIC FORESTS

This study aimed to evaluate the biomass and chemical composition of the forest floor litter in three remnants of Submontane Dense Ombrophilous Forest located in the Guaricica Natural Reserve in the municipality of Antonina, state of Paraná, Brazil. The areas selected for this study are at different stages of secondary succession, here named initial stage (INI), intermediate stage (INT), and advanced stage (ADV). The litter was collected in different seasons of the year (summer and winter of 2013 and 2014) and sorted into fractions: whole leaves (WL), leaves under some stage of decomposition (DL), miscellaneous litter (ML), and branches (B). After sorting, the litter was oven-dried, weighed, and had the contents of C, N, P, K, Ca, and Mg measured. After that, the accumulated amount of each nutrient in the different litter fractions was estimated. Accumulation of biomass in the INI was lower than that in the ADV. The DL fraction showed the highest level of biomass accumulation among all fractions. The average concentration of macronutrients in the litter showed the following sequence: C>N>Ca>Mg>K>P. The C/N ratio was higher in the INI and INT compared with that in the ADV. Higher levels of macronutrients were frequently observed in the ADV. Inputs of C and of most nutrients increased from the INI to the ADV, except for Ca, whose input varied little throughout the different successional stages.

Light controls alpine meadow community assembly during succession by affecting species recruitment from the seed bank.

Some research indicates that soil seed banks can promote species coexistence through storage effects. However, the seed bank mechanism that maintains plant assembly and its role in degraded grassland restoration are still not clear. We collected seed bank samples from early, mid and late secondary successional stages of an abandoned subalpine meadow on the Tibetan Plateau, and samples from each stage were exposed to full (i.e., natural), mid, and low light treatments in the field to represent light availability at the bottom/understory (soil surface) of a plant community in the early, mid and late stages of succession, respectively. Species richness, seed density, species composition, and community weighted mean values (CWMs) of seed mass of the species whose seeds germinated in soil samples were evaluated. In response to the light treatments, species richness increased significantly with increased light only for the late successional stage, seed density increased significantly with increased light only in the early and mid successional stages, and seed mass decreased significantly with increased light only in the mid and late successional stages. Species composition differed significantly among the light treatments only in the late successional stage. For the successional series, species richness and seed mass of the species that germinated increased significantly with succession only under mid and full light treatments. Seed density decreased significantly with succession in each light treatment. Species composition differed significantly between the early- and late stage and between the mid and late stage in each light treatment. Both the abiotic (light) and biotic (seed mass) factors influence seed bank recruitment to the plant community. Regeneration of small-seeded species in the seed bank was inhibited under low light in the late successional stage. The balance of stochastic and deterministic processes along a successional gradient was determined by regeneration from the seed bank depending on light intensity change. Differences in seed response to light intensity change largely determined plant community assembly. Our findings should help in the development of effective conservation and restoration strategies.

亚热带森林演替阶段下不同光环境对芒萁光合生理的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 亚热带森林演替阶段下不同光环境对芒萁光合生理的影响 DOI: 10.5846/stxb202112273661 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31971623）；浙江省"尖兵""领雁"研发攻关计划项目（2022C02019） Effects of different light environments on photosynthetic physiology of Dicranopteris dichotoma under successional stages in subtropical forests Author: Affiliation: Fund Project: The National Natural Science Foundation of China (31971623)； 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:光环境的变化是群落演替进程中植物进入和退出群落的重要因素。为研究亚热带森林次生演替不同阶段的光照对芒萁光合生理的影响，对灌草丛、马尾松林和常绿阔叶林这3种群落内盆栽芒萁的光响应过程和叶绿素荧光诱导动力学参数进行了研究。结果表明：芒萁在光强为400 μmol m-2 s-1左右且日变化幅度较小的马尾松林下净光合速率（Pn）最高，在光强50 μmol m-2 s-1左右的常绿阔叶林下次之，在400-1800 μmol m-2 s-1左右波动的灌草丛内最低。这是因为灌草丛内芒萁J点相对可变荧光（Vj）、K点标准化后的相对可变荧光（Wk）显著升高，以吸收光能为基础的光系统Ⅱ性能指数（PSⅡ）（PIABS）显著降低，而热耗散参数（φDo）基本不变，即强光破坏了芒萁光合机构PSⅡ的供体侧和受体侧，使其产生了光抑制。常绿阔叶林内芒萁叶绿素荧光诱导动力学参数与马尾松林下差异不明显，且最大净光合速率（Pmax）下降是光强变弱导致的，但是暗呼吸速率（Rd）、光补偿点（LCP）和光饱和点（LSP）均随之降低，可见芒萁光合机构对该光强有一定的适应性。由此可知，芒萁喜光但不耐强光，对弱光具有一定耐受性。 Abstract:The light changes of forest succession play important roles in the presence or absence of plant species in communities. To reveal the effects of light on photosynthetic physiology of Dicranopteris dichotoma at different stages of secondary succession in subtropical forests, light response process and chlorophyll fluorescence induction kinetic parameters of D. dichotoma growing in three different communities (scrub, Pinus massoniana forest, and evergreen broadleaf forest) were investigated in this experiment. The results showed that the net photosynthetic rate (Pn) was the highest in the P. massoniana forest with a light intensity of about 400 μmol m-2 s-1 and a small daily variation, followed by the evergreen broadleaf forest with a light intensity of about 50 μmol m-2 s-1, and the lowest in the scrub with a fluctuation of about 400-1800 μmol m-2 s-1. The lowest Pn in the scrub was because high light disrupted donor and acceptor sides of photosystem II (PSII) of D. dichotoma, and resulted in photoinhibition of D. dichotoma, which were proved by significantly increased relative variable fluorescence (Vj) at point J, normalized relative variable fluorescence (Wk) at point K, and significantly decreased PSII performance index (PIABS), and unchanged heat dissipation parameter (φDo). No significant differences in chlorophyll fluorescence induction kinetics between the D. dichotoma growing in evergreen broad-leaved forest and P. massoniana forest indicated that its PSII was not damaged, and the decrease of the maximum net photosynthetic rate (Pmax) was caused by the low light. At the same time, the reduced dark respiration rate (Rd), light compensation point (LCP), and light saturation point (LSP) showed that D. dichotoma photosynthetic system could adapt to the low light in the evergreen broad-leaved forest. This study showed that D. dichotoma was a light-loving but not light-tolerant species, with the modest low-light tolerance. 参考文献 相似文献 引证文献

A dataset of species composition and biomass in successional stages of Tiantong typical evergreen broad-leaved forest (2008–2017)

As a basic properties of forest vegetation, forest succession law is the basis understanding . Typical evergreen broad-leaved forest a zonal vegetation in the subtropical area of China. The existing vegetation is mostly in different secondary succession stages due to human and natural disturbance. lant species is an important indicator of the forest ecosystem and the basis for the study o structure, function and dynamics of evergreen broad-leaved forest. According to CNERN monitoring standards, Zhejiang Tiantong Forest Ecosystem Observation and Research Station three three succession plots and established a dataset species composition 2008 to 2017. The succession plots are evergreen shrub plot, Schima Superba forest plot and Castanopsis fargesii forest plot, respectively species name, abundance, mean diameter and biomass of woody plants the plots. The database provides critical data for the study and application of succession, community assembly and forest restoration in subtropical typical evergreen broad-leaved forests.

The legacy of forest logging on organic matter inputs and storage in tropical streams

AbstractRiparian forests play an important role in stream ecosystems, as they support biodiversity, reduce water erosion, and provide litter that fuels aquatic biota. However, they are affected by great array of anthropogenic threats (e.g., fire, logging, and organic pollution), which alter species composition and their physical structure. Although forest recovery after disturbance such as logging can take decades, the legacy of forest clear‐cut logging on key processes in tropical riparian ecosystems is mostly unknown. Here, we investigated how litter inputs (leaves, twigs, and reproductive parts) and storage, key processes for carbon and nutrient recycling and for forest and stream biota, are influenced by riparian vegetation undergoing succession (after 28 years from logging) through the comparison of reference and logged forest sites in the Cerrado biome. Litterfall was overall similar between forest types, but litterfall of twigs was twofold higher at logged than reference sites. Similarly, litter inputs from the bank to the stream (i.e., lateral inputs) and streambed storage were 50–60% higher at logged than reference sites. The higher litterfall observed in logged forests could be related to higher proportion of tree species that are characteristic of primary and secondary successional stages, including fast‐growing and liana species, which often are more productive and common in anthropogenic areas. Our results showed that the legacy impact of clear‐cut logging, even if residual woody vegetation is maintained in riparian buffers, can shift the type, quantity, and seasonality of litter subsidies to tropical streams. This knowledge should be considered within the context of management and conservation of communities and ecosystem processes in the forest‐stream interfaces.Abstract in Portuguese is available with online material.

Effect of plant–plant interactions and drought stress on the response of soil nutrient contents, enzyme activities and microbial metabolic limitations

Plant–plant interactions are dynamic and complicated processes that strongly influence soil nutrient cycling in ecosystems. Climate warming-induced drought stress and the duration of plant interactions may reshape or complicate this ecological process. However, little is known about how plant–plant interaction time (co-growth duration) combined with drought stress affect soil chemical properties and enzyme activities. In this study, Stipa bungeana and Bothriochloa ischaemum, which were the main plant species during the later stages of secondary succession in an abandoned cropland on the Loess Plateau of China, were planted as a single plant or in combination, in a plastic pot with two water regimes (ample water, 80 % of field capacity (FC); drought stress, 60 % of FC) for two consecutive years. The rhizosphere soil was collected each year to determine the nutrient contents and enzyme activities, and the microbial metabolic limitations were calculated. We found that plant–plant interactions, drought stress, and sampling year had a significant influence on most rhizosphere soil nutrient contents and enzyme activities. Redundancy analysis showed that soil pH, available phosphorus (aP), and total phosphorus had significant effects on soil enzyme activities in the first year, and soil total nitrogen and aP had significant effects on soil enzyme activities in the second year. Vector analysis indicated that drought stress increased microbial carbon (C) and phosphorus (P) limitation under each planting pattern, and these metabolic limitations showed a decreasing trend in the second year. An structural equation model demonstrated that plant–plant interactions on microbial C and P limitation were larger than drought stress in the first year. Conversely, in the second year, the plant–plant interactions on microbial C and P limitation were lower than that of drought stress. Our findings highlighted that the duration of plant–plant interactions had a significant influence on C flows and nutrient cycling in plant–soil systems, and improved the understanding of plant–plant interactions and drought stress on soil nutrient cycling and microbial metabolic limitations in vegetation restoration ecosystems.

Aboveground carbon accumulation by second‐growth forests after deforestation in Hawai'i

Successional processes ultimately determine and define carbon accumulations in forested ecosystems. Although primary succession on wholly new substrate occurs across the globe, secondary succession, often following storm events or anthropogenic disturbance, is more common and is capable of globally significant accumulations of carbon (C) at a time when offsets to anthropogenic carbon dioxide (CO2 ) emissions are critically needed. In Hawai'i, prior studies have investigated ecosystem development during primary succession on lava flows, including estimates of C mass accumulation. Yet relatively little is known regarding secondary succession of Hawaii's native forests, particularly regarding C mass accumulation. Here we documented aboveground C mass accumulation by native- and nonnative-dominated second-growth forests following deforestation of mature native lowland rainforests in the Puna District of Hawai'i Island. We characterized species composition and stand structure of three distinct successional forest stand types: those dominated by the native tree, Metrosideros polymorpha ('Ōhi'a), and those dominated by invasive nonnative trees, Falcataria moluccana (albizia) and Psidium cattleianum (strawberry guava). We compared M. polymorpha-dominated and F. moluccana-dominated second-growth forests to adjacent mature M. polymorpha-dominated forests as well as young M. polymorpha-dominated forests undergoing initial stages of primary succession on 36-years-old lava fields. Aboveground carbon density (ACD) values of mature primary forest stands (171 Mg/ha) were comparable to those of mature continental tropical forests. M. polymorpha-dominated second-growth stands attained nearly 50% of ACD values of mature primary forests after less than 30 years of post-disturbance succession and exhibited aboveground carbon accumulation rates of ~3 Mg C·ha-1 ·year-1 . Such rates were comparable to those of second-growth forests in continental tropics. Rates of ACD accumulation by second-growth forests dominated by nonnative F. moluccana stands were similar, or slightly greater than, those of M. polymorpha-dominated stands. However, M. polymorpha individuals were virtually absent from stands dominated by either P. cattleianum or F. moluccana. Taken together, results demonstrated that re-establishment and rapid accumulation of C mass by M. polymorpha stands during secondary succession is certainly possible, but only where populations of nonnative species have not already colonized areas during early stages of secondary succession.

Trajectories in nitrogen availability during forest secondary succession: illustrated by foliar \u03b415N

BackgroundForest succession is an important ecological process and has been studied for more than a century. However, changes in nitrogen (N) availability during succession remain unclear as they may lead to either N saturation or N limitation. Here, we propose a conceptual model to illustrate changes in N availability during four stages of secondary succession using the natural abundance of 15N in plant leaves (foliar δ15N). We predicted that N availability would decline in the early stages of succession and then increase in late stages, coinciding with the changes in foliar δ15N, with the inflection point varying in different climate zones. Data on foliar δ15N from 16 succession sequences were synthesized to explore changes in N availability during forest succession.ResultsThe compiled data were consistent with the proposed conceptual model. Foliar δ15N in boreal and temperate forests decreased significantly in the first two stages of succession (estimated to last at least 66 years in temperate forests), at a rate of 0.18‰ and 0.38‰ per decade, respectively, and decreased slightly in tropical forests in the first 23 years. Foliar δ15N is projected to increase in later stages in all forests, which is supported by observations in both temperate and tropical forests. The inflection points of N availability when N limitation peaked during succession were different in different climate zones, implying different ecosystem N turnovers.ConclusionsOur study reconciles the controversies regarding changes in N availability during forest secondary succession. Our findings are also useful for predicting the recovery of N and carbon accumulation during succession. Nonetheless, studies on forest secondary succession using foliar δ15N have thus far been limited, and more research should be conducted to further verify the conceptual model proposed here.

Response of surface-soil quality to secondary succession in karst areas in Southwest China: Case study on a limestone slope

Karst areas are fragile ecological environments facing serious soil quality problems. It is crucial to understand the surface-soil quality for ensuring the secondary succession of vegetation. In this study, four plots located on the same hill slope were selected, representing the four secondary succession stages of arable land, grassland, shrubs, and secondary forest, respectively. The surface-soil quality during secondary succession is assessed using the minimum dataset method. The results show that secondary succession decreased soil bulk density and total potassium content (P < 0.05), whereas soil organic matter, saturated hydraulic conductivity, overall porosity, and total nitrogen increased (P < 0.05). However, pH and capillary porosity are relatively stable. Non-capillary porosity and total phosphorus content first decreased and then increased. In addition, the mean soil quality indices increased and the difference in surface-soil quality between stages decreased with vegetation succession (P < 0.05). Improvement in surface-soil quality is most obvious in the early stages of secondary succession, and natural vegetation restoration can solve the land degradation problem. This study is not only helpful in understanding the changes in surface-soil quality during the secondary succession but also provides a theoretical basis for selecting ecological restoration methods in karst regions.

The competitive mechanism between post-abandonment Chinese fir plantations and rehabilitated natural secondary forest species under an in situ conservation policy

During the past 30 years, the global forest area has been subject to a continuous increase in planted forests and a decline in natural forests, raising significant concerns about biodiversity protection. Once these plantations are abandoned due to changes in conservation or forest management policies, can they recover to the same state as natural forests during secondary succession? The key ecological processes supporting the stable coexistence or competitive elimination mechanisms between post-abandonment plantations and natural secondary forest tree species are still poorly understood and may be the decisive ecological processes driving secondary forest restoration. A 12-ha long-term forest plot was established in an abandoned Chinese fir plantation that has been protected under an in situ protection policy for 40 years. In total, 66,317 individual trees were stem mapped and identified at the species level, and the spatial survival strategies and species coexistence mechanisms between Chinese fir and natural secondary forest tree species were investigated. The results showed that the spatial survival strategy of Chinese fir could effectively trade off a high conspecific density-dependent mortality rate of individuals during the early stage of secondary succession for the long-term survival of the whole population, which promoted its dominance during later stages of succession. By contrast, although the higher survival rate and larger intraspecific aggregation scale of natural secondary forest individuals favored their survival during initial colonization, this spatial survival strategy might occur at the cost of neglecting suitable habitats and the loss of competitive advantages at the later stage of succession. Regarding interspecific competition, the asymmetric competition process further ensured the advantages of Chinese fir in individual size growth and increased the competitive advantage of Chinese fir over natural secondary forest tree species by exclusion through interspecific competition during the later secondary succession stage. Our results suggest that implementing a forest recovery program or an in situ protection policy based on post-abandonment monoculture plantations may involve great uncertainty about whether the goal can be achieved. Specifically, although this strategy could quickly increase forest coverage and restore the forest landscape, it may also create difficulties in restoring the forest to its original state.

Afrotropical secondary forests exhibit fast diversity and functional recovery, but slow compositional and carbon recovery after shifting cultivation

AbstractQuestionsHuman disturbance is increasingly affecting forest dynamics across the tropics. Forests can recover via natural secondary succession to pre‐disturbance levels of biodiversity, species composition, and ecosystem carbon stocks. Central Africa will be subject to increasingly high shifting‐cultivation pressure in the next decades, but succession trajectories of these ecosystem properties are still poorly known for the Congo basin. We addressed two questions: (1) how does taxonomic and functional composition and diversity shift during secondary succession; and (2) how fast do above‐ground carbon stocks recover during secondary succession in tropical forests?LocationCentral Congo basin.MethodsWe conducted an inventory of trees (diameter at breast height [DBH] ≥ 10 cm), measured species traits and soil texture and carbon content in 18 plots, located along six secondary succession stages (i.e., from agricultural to old growth forest sites). We measured tree diameter, height for 20% of trees distributed across diameter classes, wood traits from all species, and leaf traits from species that contributed to 85% of the plot basal area.ResultsWe showed that secondary forests recover relatively fast in terms of tree species diversity, alpha functional diversity, and fine‐root carbon, with near‐old‐growth forest values after six decades past disturbance, while floristic composition exhibited slower recovery. Secondary forests only partially shifted from acquisitive to a conservative life history, with shifts in leaf traits being largely decoupled from wood traits. Only 43% of above‐ground carbon recovered after 60 years of forest regrowth, potentially through a slow recovery of the large‐sized tree stems that dominate carbon stocks of old‐growth forests.ConclusionsOur findings underline the capacity of Afrotropical forests to recover species and alpha functional diversity after clear‐cutting through shifting cultivation. Simultaneously, old‐growth forests harbor a particular floristic community and store a large quantity of carbon with much longer recovery trajectories, stressing the need for conservation of these forests in the Congo basin.

Succession of Xeric Calcareous Grassland Toward Thermophilous Oak Forest: The Case of Abava Valley, West Latvia

Abstract The succession of semi-natural xeric calcareous grassland plant communities toward deciduous forest communities is poorly studied in Latvia. There is insufficient knowledge on the natural transformation of dry calcareous grasslands of Festuco-Brometea into thermophilous quasi-climax oak forest communities of Quercetea pubescentis that are very rare in Latvia. In this paper, a geobotanical study is presented that included studies of soils, tree age, spatial pattern of trees, vegetation composition of different succession stages, and analysis of environmental factors. The study was conducted in the Abava Valley, West Latvia, an area that is unique with species-rich xeric calcareous Festuco-Brometea grasslands, thermophilous oak forests dominated by Quercus robur, and intermediate secondary succession stages with young to medium-aged Juniperus communis and Pinus sylvestris formations.

Effects of Soil Properties and Plant Diversity on Soil Microbial Community Composition and Diversity during Secondary Succession

Soil microbial communities play an important role in maintaining the ecosystem during forest secondary succession. However, the underlying mechanisms that drive change in soil microbial community structures during secondary succession remain poorly defined in species-rich subtropical coniferous forests. In this study, Illumina high-throughput sequencing was used to analyze the variations in soil microbial community structures during forest secondary succession in subtropical coniferous forests in China. The role of soil properties and plant diversity in affecting soil bacterial and fungal communities was determined using random forest and structural equation models. Highly variable soil microbial diversity was observed in different stages of secondary succession. Bacterial community diversity rose from early to middle and late successional stages, whereas fungal community diversity increased from early to middle successional stages and then declined in the late stage. The relative abundance of Acidobacteria, Gemmatimonadetes, Eremiobacterota(WPS-2), Rokubacteria, and Mortierellomycota increased during succession, whereas the relative abundance of Ascomycota and Mucoromycota decreased. The community composition and diversity of the soil microbial community were remarkably influenced by plant diversity and soil properties. Notably, tree species richness (TSR) displayed a significant and direct correlation to the composition and diversity of both bacterial and fungal communities. The carbon-to-nitrogen (C:N) ratio had a direct impact on the bacterial community composition and diversity, and pH had a marked impact on the fungal community composition and diversity. Furthermore, succession stage and plant diversity indirectly impacted the composition and diversity of soil bacterial and fungal communities via soil properties. Overall, it can be concluded that soil intrinsic properties and plant diversity might jointly drive the changes in soil microbial community composition and diversity during secondary succession of subtropical coniferous forests.

A Remote Sensing Approach to Understanding Patterns of Secondary Succession in Tropical Forest

Monitoring biodiversity on a global scale is a major challenge for biodiversity conservation. Field assessments commonly used to assess patterns of biodiversity and habitat condition are costly, challenging, and restricted to small spatial scales. As ecosystems face increasing anthropogenic pressures, it is important that we find ways to assess patterns of biodiversity more efficiently. Remote sensing has the potential to support understanding of landscape-level ecological processes. In this study, we considered cacao agroforests at different stages of secondary succession, and primary forest in the Northern Range of Trinidad, West Indies. We assessed changes in tree biodiversity over succession using both field data, and data derived from remote sensing. We then evaluated the strengths and limitations of each method, exploring the potential for expanding field data by using remote sensing techniques to investigate landscape-level patterns of forest condition and regeneration. Remote sensing and field data provided different insights into tree species compositional changes, and patterns of alpha- and beta-diversity. The results highlight the potential of remote sensing for detecting patterns of compositional change in forests, and for expanding on field data in order to better understand landscape-level patterns of forest diversity.