Secondary Broad-leaved Forest Research Articles

Alpha and beta diversity of functional traits in subtropical evergreen broad-leaved secondary forest communities.

Intra-speciic variation is the main source of functional trait diversity and has similar ecological effects as inter-speciic variation. We studied 79 species and 3546 individuals from 50 ixed monitoring plots in subtropical evergreen broad - leaved secondary forests in Zhejiang Province, China. Using trait gradient analysis, we examined nine traits (speciic leaf area, leaf dry matter content, wood density, leaf area, chlorophyll content, leaf nitrogen content, leaf phosphorus content, leaf potassium content, and nitrogen-phosphorus ratio) by decomposing species functional traits into alpha (within-community) and beta (among-communities) measure the impact of environmental gradients and the presence of other species on the variation of traits. All nine functional traits showed some degree of differentiation in the forest communities, with a greater range of variation in alpha values than in beta values . Correlations were signiicantly different between the trait differences in the communities. The alpha values of each trait showed a higher correlation with other components than the beta values. The factors affecting intra-speciic trait variation were relatively complex. The alpha component had a more signiicant and stronger effect on intra-speciic trait variation compared to the beta component. Abiotic factors, such as soil nutrient content, soil nitrogen-phosphorus content, directly affected the beta component. In contrast, biotic factors, such as tree height variation, had a direct and stronger effect on the alpha component. Our results demonstrate that alpha and beta components, as independent differentiation axes among coexisting species, have different sensitivities to different environmental factors and traits in different ecological strategies and spatial scales. Trait gradient analysis can more clearly reveal the variation patterns of species traits in communities, which will help to understand the scale effects and potential mechanisms of trait relationships.

Spatial Distribution and Sustainable Development of Living Woody and Coarse Woody Debris in Warm-Temperate Deciduous Broadleaved Secondary Forests in China.

The investigation into the spatial patterns of living woody (LWD) and coarse woody debris (CWD) in warm-temperate deciduous broadleaved secondary forests serves as a foundational exploration of the mechanisms governing coexistence and mortality in forest ecosystems. The complete spatial randomness null model (CSR) was employed to analyze spatial distribution patterns, with the independent component null model (IC) and canonical correspondence analysis (CCA) utilized to elucidate spatial correlations and topographic influences. All three models were applied to LWD and CWD across various size classes within a 20-hectare plot in the Dongling Mountains. The study's findings indicate that both LWD and CWD predominantly exhibited aggregated patterns, transitioning to a random distribution as the size class increased. Both increasing abundance and maximum diameter at breast height (DBH) also have a significant influence on the distribution of species. Notably, rare species exhibited higher aggregation compared to common and abundant species. The spatial correlation results between LWD and CWD across various size classes predominantly showed positive correlations and uncorrelated patterns within the sampled plots. CCA analysis further revealed that elevation, convexity, slope, and aspect significantly influenced the spatial patterns of LWD and CWD across different size classes. Within the sample site, trees display a tendency to grow and die in clusters. Biotic factors have a more significant influence on species distribution than abiotic factors.

Rhizosphere effects of moso bamboo and dominant tree species of secondary broadleaved forest on soil organic carbon mineralization.

The rhizosphere effect of plants affects soil organic carbon (SOC) mineralization. It is still unclear for the mechanism by which the rhizosphere effect of dominant plants in secondary broadleaved forest habitats invaded by moso bamboo affects SOC mineralization. Taking broadleaved tree species (Quercus glauca and Cunninghamia lanceolata) and moso bamboo, dominating respectively in uninvaded secondary broadleaved forest and bamboo forest formed after the invasion as test materials, we investigated rhizosphere effect of plants on the SOC mineralization in laboratory incubation experiments. The results showed that carbon mineralization rates of Phyllostachys edulis (PE), Quercus glauca (QG) and Cunninghamia lanceolata (CL) rhizosphere soils were 20%, 26%, and 21% higher than bulk soils, respectively. Carbon mineralization of bulk soils of QG and CL was 22% and 26% higher, while that of rhizosphere soils was 14% and 11% higher than PE, respectively. The contents of water-soluble organic carbon and organic carbon in rhizosphere soils of the three species were significantly higher than those of bulk soil, and the abundance of rhizosphere soil bacteria was higher than that of non-rhizosphere. The contents of microbial biomass carbon, water-soluble organic carbon, and total nitrogen were important factors influencing carbon mineralization in rhizosphere, while water-soluble organic carbon and microbial metabolic quotient were important factors influencing carbon mineralization in non-rhizosphere. On the whole, the rhizosphere effect increased total SOC mineralization, driving by changes in microbial biomass carbon, water-soluble organic carbon, and total nitrogen content. The results could provide a theoretical basis for plant-soil interaction on soil carbon cycling in bamboo invasion habitats.

Forest Conversion Changes Soil Particulate Organic Carbon and Mineral-Associated Organic Carbon via Plant Inputs and Microbial Processes

Primary forest conversion greatly influences soil organic carbon (SOC) sequestration. However, our understanding of how primary forest conversion affects SOC fractions and chemical component evenness remains limited. We examined how primary forest conversion (from primary mixed broadleaved Korean pine forest to secondary broadleaved forest and coniferous plantation) affects free particulate OC (POC), aggregate-occluded POC, mineral-associated OC (MAOC), and their chemical component evenness via plant inputs (e.g., litter and fine roots) and microbial properties (e.g., microbial biomass and residue C) in Northeast China. Primary forest conversion led to a large increase in litter and fine root quality (lower C/N ratio), SOC, and MBC of secondary forests and a reduction in litter and fine root quantity and quality, SOC, MBC, and microbial residue C of plantations, which drove changes in POC and MAOC. As a result, after conversion to secondary forests, free POC decreased by 20.3% and aggregate-occluded POC increased by 57.2%. After conversion to plantations, free POC increased by 49.1%, while aggregate-occluded POC and MAOC decreased by 42.4% and 9.0%, respectively. Free POC was negatively correlated with fine root biomass. Aggregate-occluded POC and MAOC were positively correlated with litter and fine root quality, MBC, and microbial residue C. Meanwhile, forest conversion decreased the evenness of free and aggregate-occluded POC chemical components in secondary forests, with O-alky C being higher and aromatic C being lower, while MAOC was not affected by forest conversion. The evenness of free and aggregate-occluded POC chemical components was associated with litter and fine root quality, and that of MAOC was associated with MBC and microbial residue C. High-quality plant inputs benefit OC sequestration in soil aggregates and MAOM through microbial assimilation and residue accumulation after primary forest conversion. Future forest management should consider tree species with high-quality input as a possible compensation for climate change by sequestering more OC in soil aggregates.

Regeneration characteristics and influencing factors of woody plant on natural evergreen secondary broad-leaved forests in the subtropical, China

Natural regeneration occupies an important position in forest ecosystems and is affected by various factors. Exploring natural regeneration and its influencing factors is helpful to understand the forest community dynamic. Evergreen broad-leaved forest is an essential zonal vegetation type in China. However, the natural regeneration of evergreen broad-leaved forests in the northernmost margin of subtropical zone has not been reported. Here we investigated 22 observed variables, and selected four categories of latent variables stand factor, topographical factor, soil factor and tree diversity as influential factors based on the survey data of 50 (20 m × 20 m) permanent sample plots. The structural equation model was introduced to distinguish the direct, indirect and total effect of influencing factors on understory woody plant regeneration diversity and regeneration density, respectively. We found 51 regeneration species under 31 families and five dominant species Loropetalum chinense, Symplocos sumuntia, Quercus glauca, Ilex chinensis, and Eurya japonica in the study area. Soil factor was the primary control of regeneration, which had the greatest and negative total effect on regeneration diversity (-0.436) and regeneration density (-0.298). The main soil factors that affected regeneration diversity and regeneration density were total phosphorus and soil organic matter, respectively. Soil factor mainly affected indirectly regeneration by mediating through its impacts on tree diversity. Tree diversity and topographical factor all were significantly positively correlated with the regeneration diversity and regeneration density. Stand factor had a significantly negative correlation with regeneration density but a significantly positive with regeneration diversity. Our study provides the basis to introduce appropriate artificial auxiliary measures for improving the natural regeneration of forest stands, so as to promote sustainable forest management.

Effects of Forest Gap on Soil Microbial Communities in an Evergreen Broad-Leaved Secondary Forest

Forest gaps play a crucial role in community succession and assembly in forest ecosystems; therefore, they have recently been recognized and implemented as effective forest management practice all over the world. Forest gaps are commonly created as small disturbances in secondary forests to improve forest regeneration, nutrient cycling, ecosystem functioning, and biodiversity. The objective of this study was to investigate the responses of the physico-chemical and biological properties and microbial communities in soil to different sizes of forest gaps—including small gaps (60–80 m2), medium gaps (130–160 m2), and large gaps (270–300 m2)—and to examine the driving factors that influence soil microbial community structure and composition. The results show that Gram-positive bacteria, Gram-negative bacteria, fungi, arbuscular mycorrhizal fungi (AMF), and actinomycetes were mainly aggregated in the gaps, and the structural diversity of soil microbial communities was related to the gap size (p < 0.05). The soil microbial community diversity increased and then decreased with an increase in gap size. Moreover, the effects of the available phosphorus, soil pH, soil water content, available potassium, nitrate nitrogen and ammonium nitrogen on changes in microbial biomass were significant (p < 0.05). The gap area and gap position and their combined interactions also had significant effects on soil nutrients, which impacts the soil microbial community. Medium gaps (130–160 m2) always significantly improved the availability of soil nutrients, and good management practices in secondary forests can provide effective microenvironments for soil microbes.

How does the 120-year cycle mast seeding of dwarf bamboo affect the rodent population?

BackgroundIn 2017, large-scale flowering, seeding, and dying events of dwarf bamboo (Sasa borealis) occurred in a wide range in central Japan for the first time in 120 years. This phenomenon of S. borealis, like the mast seeding of trees, could be expected to provide a large amount of food for seed-eating rodents and gradually affect their ecology and population dynamics. We captured rodents in survey plots in a secondary broad-leaved forest with the phenomenon from 2018 to 2019 to investigate the species, the number of individuals, growing stage, sex, and body mass. In addition, we also compared the capture data for 2 years (2018–2019) with that for the mast seeding year (2017) and 6 years before it (2011–2016).ResultsThe mast seeding of S. borealis greatly increased the population size of rodents, especially Apodemus speciosus and A. argenteus. Conversely, Eothenomys smithii did not show such an increase. Most of the captured rodent individuals were already adults at the time of new capture, and the proportion of male juveniles was extremely low. These results suggest that the mast seeding of S. borealis created unusually rich food availability for the population concentration of rodents due to their immigration. However, body mass was not significantly different before and after the mast seeding. In addition, the increased populations of the two Apodemus species did not decline 2 years after the S. borealis masting, contrary to the previously reported decrease of rodent populations after tree masting.ConclusionsOur results indicate that the mast seeding of S. borealis affected the population dynamics of Apodemus species over a long time and their individual composition of different growth stages. However, it did not affect their body mass.

杭州午潮山天然次生林木本幼苗组成及其时空分布格局

PDF HTML阅读 XML下载 导出引用 引用提醒 杭州午潮山天然次生林木本幼苗组成及其时空分布格局 DOI: 10.5846/stxb202105191310 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 浙江省省属科研院所扶持专项(2021F1065-6，2020F1065-4) Composition and the spatio-temporal distribution pattern of tree seedling in natural secondary forest of Wuchao Mountain, Hangzhou Author: Affiliation: Fund Project: Zhejiang Provincial Research Institutes Support Special Projects(2021F1065-6, 2020F1065-4)。 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:木本植物幼苗是森林生态系统的重要的组成部分,其定居、存活、生长的生态学过程对于森林植被的更新具有潜在指示和筛选作用。为探究浙江杭州午潮山亚热带常绿阔叶次生林群落更新和演替机制,基于样方法对150 m2样地内天然更新幼苗的物种组成、数量特征和基径结构进行统计,在此基础上采用最近邻分析和Ripley's K函数的点格局方法,分析其中主要优势树种的更新动态及其时空分布格局。结果表明:(1)样地内乔木幼苗树种组成丰富,共调查到幼苗811株,隶属12科20属27种,其中樟科Lauraceae、壳斗科Fagaceae、山茶科Theaceae和山矾科Symplocaceae为主要优势科。(2)红楠Machilus thunbergii、薄叶润楠M. leptophylla、毛柄连蕊茶Camellia fraterna和刨花润楠M. spauhoi在所有调查物种重要值排序前4,因而被确定为优势林下植物,绘制的基径结构小提琴图(violin plot)进一步显示它们的种群分属快速增长型、稳定增长型、缓慢增长型和稳定型。(3)红楠、薄叶润楠和刨花润楠在小径级和小尺度上多呈聚集分布,随生长发育和空间尺度的增加,聚集强度呈现先增高后降低趋势,最终向离散分布或随机分布转变,可视为群落演替的早期树种;同时,三者在聚集强度上有所差异,排序为红楠＞薄叶润楠＞刨花润楠。毛柄连蕊茶Camellia fraterna种群密度较低,在小径级和小尺度上呈随机分布,随生长发育和空间尺度的增加,聚集强度呈波动趋势,最终向离散分布转变,可视为演替的中期树种。本研究在小尺度上初步揭了午潮山木本幼苗种群的演替过程中的种群结构和分布格局,可以为亚热带森林管理与植被恢复提供理论依据。 Abstract:Woody plant seedlings are an essential part of the forest ecosystem, and their ecological processes of settlement, survival and growth are potential indicators and screening for forest vegetation regeneration. To explore the regeneration and succession mechanism of the community of the subtropical evergreen broad-leaved secondary forest in Hangzhou Wuchao Mountain, Zhejiang Province, the species composition, quantitative characteristics and stem base diameter (SBD) classes of the natural regeneration seedlings in a 150 m2 plot were counted based on the sample plot method. On this basis, the nearest neighbor analysis (NNA) and the point pattern method of Ripley's K function were adopted to analyze the regeneration dynamics of the main dominant tree species and their spatio-temporal distribution patterns. Results showed that (1) tree seedlings in the plot are rich in species composition. A total of 811 seedlings were investigated, belonging to 12 families, 20 genera and 27 species, among which Lauraceae, Fagaceae, Theaceae and Symplocaceae are the main dominant families. (2) Machilus thunbergii, M. leptophylla, Camellia fraterna and M. spauhoi were identified as dominant understory plants, ranking the top four position in importance values of all investigated species. Meanwhile, the violin plot of the SBD classes further shows that the populations of these species belong to the fast-growing type, stable-growing type, slow-growing type and stable type, respectively. (3) M. thunbergii, M. leptophylla and M. spauhoi are mostly clustered at the small SBD classes and small scales. With the increase of growth and spatial scale, the clustering intensity firstly increases and then decreases, and finally changes to a discrete distribution or a random distribution. As the growth and development and the spatial scale increase, the aggregation intensity fluctuates and eventually transforms to a discrete distribution, which can be regarded as a mid-term succession tree species. Meanwhile, the three trees are different in the intensity of aggregation, sorted as M. thunbergii > M. leptophylla > M. spauhoi. The population density of Camellia fraterna is relatively low, and it is randomly distributed on small SBD classes and small scale. With the increase of growth and spatial scale, the aggregation intensity fluctuates, and finally becomes a discrete distribution. Therefore, C. fraterna can be regarded as the middle stage of succession. This study initially revealed the population structure and distribution pattern in the succession process of Wuchao Mountain woody seedling population on a small scale, which can provide a theoretical basis for subtropical forest management and vegetation restoration. 参考文献 相似文献 引证文献

极小种群野生植物细果秤锤树种群结构与动态特征

PDF HTML阅读 XML下载 导出引用 引用提醒 极小种群野生植物细果秤锤树种群结构与动态特征 DOI: 10.5846/stxb202104291124 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 浙江省珍稀濒危野生动植物抢救保护行动(2021-2025);基于功能群的亚热带次生阔叶林质量提升技术研究与示范(2019SY08) Population structure and dynamic characteristics of an extremely small population plant Sinojackia microcarpa Author: Affiliation: Fund Project: Zhejiang Provincial Action for the Rescue and Protection of Rare and Endangered Wild Animals and Plants (2021-2025);Study and demonstration on quality improvement technology of subtropical secondary broad-leaved forest based on functional group (2019SY08) 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:细果秤锤树(Sinojackia microcarpa)是中国特有极小种群植物之一,属国家Ⅱ级重点保护植物。为揭示该种群的生存潜力与濒危机制,为种群保护提供依据,采用样地调查法在浙江省建德市细果秤锤树自然集中分布区进行野外调查,以空间代替时间研究了细果秤锤树种群的结构特征,绘制了种群静态生命表及种群存活曲线,并应用种群动态和时间序列量化预测种群未来发展态势。结果表明:(1)细果秤锤树的径级、高度和冠幅结构均表明该种群龄级结构总体呈衰退型,种群幼年树淘汰率较高,中年树到老年树过渡阶段适应力增强,生长情况较前期稳定。(2)生活曲线属Deevey-Ⅲ型,早期死亡率高,生存分析揭示细果秤锤树种群具有前期锐减的动态特征。(3)时间序列分析预测在未来2、4、6、8个龄级后,细果秤锤树的年龄结构存在幼年个体数下降,中、老年树占优势的衰退风险。(4)种群动态指数表明该种群结构总体波动大,抗外界干扰能力较弱,环境对个体的选择作用较强。为促进种群自然更新,应加强就地保护措施,降低人为干扰对个体生存环境的威胁,提高幼苗至幼树转化率,实现种群恢复。 Abstract:Sinojackia microcarpa is one of the extremely small populations species in China, it is a level-Ⅱ national key protected plant. To reveal the survival potential and endangered mechanism of the population, and provide the basis for population protection, a sample survey was conducted in the natural concentrated distribution area of S. microcarpa in Jiande City, Zhejiang Province. The structural characteristics of S. microcarpa were studied in space instead of time, the population static life table and population survival curve were drawn, and the population dynamics and time series were used to quantitatively predict the future development trend of the population. The results showed that: (1) The structure of diameter, height and crown structure all indicated that the age structure of the population was generally declining, the young trees had high mortality, while the adaptability of the adult tree to the old tree was enhanced, and the growth situation was stable compared with the previous period. (2) The life curve belonged to the Deevey-Ⅲ type, survival analysis showed that the population of S. microcarpa had a sharp decline in the early stage and the early mortality rate was high. (3) Time series analysis predicted that after 2, 4, 6, and 8 age classes in the future, the number of young individuals of S. microcarpa will decline, and the age structure will be in a decline dynamic where adult trees dominate. (4) The population dynamic index indicated that the overall structure of the population fluctuated greatly, the ability to resist external interference was weak, and the environment had a strong effect on individual selection. In order to promote the natural renewal of the population, in-situ protection measures should be strengthened to reduce the threat of human interference to the individual living environment, it will help increase the conversion rate of seedlings to saplings, and achieve the restoration of population. 参考文献 相似文献 引证文献

毛竹林和阔叶林凋落物互置对土壤氮矿化的影响及微生物贡献

PDF HTML阅读 XML下载 导出引用 引用提醒 毛竹林和阔叶林凋落物互置对土壤氮矿化的影响及微生物贡献 DOI: 10.5846/stxb202012313329 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（32071742，31670618） Effects of exchanging litters on soil nitrogen mineralization and microbial contributions in Moso bamboo (Phyllostachys edulis) and broad-leaved forests Author: Affiliation: Fund Project: This work was supported by National Natural Science Foundation of China (31670618). 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:凋落物输入方式的改变导致凋落物数量和质量发生变化，进而对森林土壤氮矿化产生影响。选择未被入侵的次生阔叶林和毛竹入侵后形成的毛竹纯林为对象，对地表凋落物进行保留、去除与置换处理，采用室内培养法同时添加抗生素（链霉素和放线菌酮）分析真菌和细菌在土壤氮素矿化中的贡献。结果表明：（1）去除凋落物处理使阔叶林土壤净氨化速率增加27.0%，净硝化速率降低11.4%；毛竹林土壤净氨化速率增加23.4%。（2）置换凋落物处理使阔叶林土壤净氨化速率增加43.8%，净硝化速率降低33.5%；毛竹林土壤净硝化速率增加73.1%。（3）添加抗生素后，凋落物置换处理与对照相比，置换凋落物后阔叶林土壤真菌和细菌在净氨化中发挥主要作用；真菌在两种林分土壤净硝化中发挥主要作用，细菌在阔叶林土壤净硝化中发挥主要作用。（4）结合测定的凋落物化学性质可知，置换凋落物后引起真菌和细菌在土壤氮素矿化中贡献发生变化，是由于输入凋落物中木质素和纤维素含量的变化。综上，凋落物去除和置换改变了土壤氮素矿化速率，置换凋落物后改变了真菌和细菌对土壤氮素矿化的贡献。解析凋落物质量在土壤氮素矿化中的作用及微生物群落的相对贡献，有助于阐明毛竹入侵阔叶林的地下生态机制。 Abstract:The type of litter input led to change in litter quantity and quality, which ultimately affected the nitrogen (N) mineralization in the forest soil. We chose two types of forest stand, (I) uninvaded secondary broadleaved forest and (II) the bamboo forest formed after Moso bamboo (Phyllostachys edulis) invasion, which was selected to retain, remove and replace the surface litters. The antibiotics (streptomycin and actinone) were added in the incubation experiment to analyze the relative contribution of fungi and bacteria to soil N mineralization. The results showed that after removal of litters, soil net ammonification rate increased by 27.0%, and net nitrification rate decreased by 11.4% under the broadleaved forest; moreover, net ammonification rate increased by 23.4% under Moso bamboo forest. In litter replaced treatments, the net ammonification rate increased by 43.8% and the net nitrification rate decreased by 33.5% under broadleaved forest; the net nitrification rate increased by 73.1% under bamboo forest. However, after adding antibiotics, soil fungi and bacteria played a significant role in soil net ammonification in the broadleaved forest compared with the control. Fungi played an influential role in soil nitrification under two forest stands, and bacteria played a major role in soil nitrification in the broadleaved forest. Finally, along with the chemical properties of litters, the alteration of contribution of fungi and bacteria to soil N mineralization was caused by the replacement of litters, which was directly related to lignin and cellulose content in litters. In conclusion, the removal and replacement of litters could change the rate of soil N mineralization, and the replacement of litters altered the contribution of fungi and bacteria to N mineralization in the forest soils. Our study provides a theoretical basis to elaborate underground ecological mechanism of Moso bamboo invasion into the broadleaved forest. 参考文献 相似文献 引证文献

C:N:P stoichiometry of different soil components after the transition of temperate primary coniferous and broad-leaved mixed forests to secondary forests

The balance of C, N, and P in plants, soil, and microbes is remarkably important for maintaining forest ecosystem stability. However, during forest transitions, the potential effects of the stoichiometric changes and correlations of different soil components on forest restoration are not clear. The restoration characteristics and ecological services of secondary forests, the world’s major forest resources, have been a hot topic of concern. In this study, we used primary Korean pine broad-leaved forests (PF) as controls and investigated the characteristics of the stoichiometry of different soil components and the microbial resource limitation in young and middle-aged (60 years) secondary broad-leaved forests (SF), which were formed after clear-cutting of PF. We found that soil resources, microbial biomass, enzymes, and their stoichiometry varied considerably with the period of sampling within the growing season, and the influence of sampling period was usually greater than that of forest type. Among the stoichiometric ratios of soil resources, the C/N ratio was found to be an important stoichiometric indicator, explaining 84.41% of the variation in forest biomass between the two forest types, and the soil C/N ratio of the SF was remarkably lower. Compared with soil microbial biomass in PF, that in SF exhibited obvious competitive patterns with plants and sensitive homeostasis regulation, suggesting that, in SF, soil microbes competed more strongly with plants for nutrients, and microbial metabolism was more susceptible to the changes in soil resources. In addition, with the exception of β-1,4-glucosidase, the seasonal coefficients of variation for β-1,4-N-acetylglucosaminidase, leucine arylamidase, and acid phosphatase were all significantly larger in SF. The temporal heterogeneity of soil enzymes between the two forest types was mainly related to the dynamic changes of microbial biomass C. The results of eco-enzymatic stoichiometry indicated that soil microbes in the two forest types were restricted by P, but the P limitation was more obvious in SF. Soil microbes in SF were more limited by C. Finally, the correlation analysis revealed that the stoichiometric ratios of the different soil components formed a complex network.

Changes in leaf litter decomposition of primary Korean pine forests after degradation succession into secondary broad-leaved forests.

Forest degradation succession often leads to changes in forest ecosystem functioning. Exactly how the decomposition of leaf litter is affected in a disturbed forest remains unknown. Therefore, in our study, we selected a primary Korean pine forest (PK) and a secondary broad‐leaved forest (SF) affected by clear‐cutting degradation, both in Northeast China. The aim was to explore the response to changes in the leaf litter decomposition converting PK to SF. The mixed litters of PK and SF were decomposed in situ (1 year). The proportion of remaining litter mass, main chemistry, and soil biotic and abiotic factors were assessed during decomposition, and then, we made an in‐depth analysis of the changes in the leaf litter decomposition. According to our results, leaf litter decomposition rate was significantly higher in the PK than that in the SF. Overall, the remaining percent mass of leaf litter's main chemical quality in SF was higher than in PK, indicating that leaf litter chemical turnover in PK was relatively faster. PK had a significantly higher amount of total phospholipid fatty acids (PLFAs) than SF during decomposition. Based on multivariate regression trees, the forest type influenced the soil habitat factors related to leaf litter decomposition more than decomposition time. Structural equation modeling revealed that litter N was strongly and positively affecting litter decomposition, and the changes in actinomycetes PLFA biomass played a more important role among all the functional groups. Selected soil abiotic factors were indirectly driving litter decomposition through coupling with actinomycetes. This study provides evidence for the complex interactions between leaf litter substrate and soil physical–chemical properties in affecting litter decomposition via soil microorganisms.

Changes in soil ammonia oxidizers and potential nitrification after clear-cutting of boreal forests in China.

The Korean pine and broad-leaved mixed forests are the most typical and complete ecosystem among the global boreal forests, with extremely important ecological functions. However, few studies on the changes of soil ammonia oxidizers and potential nitrification after clear-cutting of forests are reported. In this study, in contrast to primary Korean pine forests, nitrate (NO3-) was significantly higher in secondary broad-leaved forests, while ammonium (NH4+) was on the contrary. The abundance of ammonia-oxidizing bacteria (AOB) was greatly higher in secondary broad-leaved forests, while levels of ammonia-oxidizing archaea (AOA) were not significantly different between them. The significant differences of community structure of AOA and AOB were observed in different forest types and soil layers. Compared with AOA, community compositions of AOB was more sensitive to forest type. The dominant groups of AOA were Nitrososphaera and Nitrosotalea, and the dominant group of AOB was Nitrosospira, of which Nitrosospira cluster 2 and 4 were functional groups with highly activity. Soil potential nitrification rate (PNR) was higher in secondary broad-leaved forests. Furthermore, PNR and AOB abundance had a significant positive correlation, but no significant correlation with AOA abundance. These results provide insights into the soil nitrogen balance and effects on forest restoration after clear-cutting.

Effect of sika deer on forest recovery after clear-cutting conifer plantations in warm temperate regions of western Japan: from a field experiment of deer exclosure and planting of Quercus acutissima

ABSTRACT A field experiment was conducted involving deer exclosures and planting of Quercus acutissima, a deciduous oak, to reveal forest recovery patterns and factors following clear-cutting at overcrowded conifer plantation sites. Sites were selected in a warm temperate region in western Japan, which is dominated by deciduous broad-leaved secondary forests and extensive conifer plantations. Thirteen years after clear-cutting in the study area, naturally regenerated stands were established with exclosures. The exclosures housed vegetation dominated by pioneer trees, such as Mallotus japonicus or Zanthoxylum ailanthoides. In contrast, naturally regenerated stands without exclosures had limited pioneer trees present. Vegetation dominated by pioneer shrubs (e.g. Aralia elata) was established in these stands. Reduced canopy height and total basal area were observed for vegetation outside the exclosures. In stands where Q. acutissima was planted immediately after clear-cutting, the vegetation that is dominated by this species in the canopy layer was established in both stands with and without exclosure. Most of tree species that emerged after clear-cutting across all stands were of the frugivore seed dispersal type. However, results from this study suggest that these frugivore seed dispersal type trees are more vulnerable to deer browsing than trees from the Fagaceae family. Natural forest recovery following plantation clear-cutting could be inhibited due to deer herbivory at relatively low deer density if a major source of tree regeneration in clear-cut plantations is non-Fagaceae trees.

Changes in fine root decomposition of primary Pinus koraiensis forest after clear cutting and restoration succession into secondary broad-leaved forest

Fine root decomposition is one of the primary mechanisms by which nutrient uptake and C exchange occur in terrestrial ecosystems, which will be likely affected by forest succession. Herein, we compared the fine root decomposition rates of primary Korean pine forest (PK) and secondary broad-leaved forest (SF) using the litter bag method; then conducted an in-depth analysis of differences in the PK and SF fine root decomposition process. Our results demonstrated that the fine root decomposition in PK was significantly faster than that in SF. In general, the percent (%) mass of the main nutrient elements remaining in SF fine roots was significantly higher than that in PK, indicating that PK can more efficiently return soil nutrients through fine root decomposition. We also found that the succession of PF to SF induced significant alternation of the microbial community composition and decreased activities of soil enzymes. Structural equation modeling further demonstrated that fine root K and lignin were the key substrate-level factors affecting fine root decomposition, while actinomycetes and fungi PLFA biomass change played the most important role among all the functional groups. Finally, we determined that fine root degradation was driven by polyphenol oxidase and acid phosphatase enzymatic activities. This study elucidates the complex interactions between fine root substrate and soil physiochemical properties and demonstrates how they affect fine root decomposition via soil microorganisms. Given that these changes continue over long time scales, the secondary forest will experience increased difficulty return to the original primary Korean pine broad-leaved forest vegetation.

Effects of Soil Microbes on Forest Recovery to Climax Community through the Regulation of Nitrogen Cycling

Microbes, as important regulators of ecosystem processes, play essential roles in ecosystem recovery after disturbances. However, it is not clear how soil microbial communities and functions change and affect forest recovery after clear-cutting. Here, we used metagenome sequencing to systematically analyse the differences in soil microbial community composition, functions, and nitrogen (N) cycling pathways between primary Korean pine forests (PF) and secondary broad-leaved forests (SF) formed after clear-cutting. Our results showed that the dominant phyla of the two forest types were consistent, but the relative abundance of some phyla was significantly different. Meanwhile, at the genus level, the fold-changes of rare genera were larger than the dominant and common genera. The genes related to microbial core metabolic functions, virulence factors, stress response, and defence were significantly enriched in SF. Additionally, based on the relative abundance of functional genes, a schema was proposed to analyse the differences in the whole N cycling processes between the two forest types. In PF, the stronger ammoniation and dissimilatory nitrate reduction (DNRA) and the weaker nitrification provided a genetic explanation for PF dominated by ammonium (NH4+) rather than nitrate (NO3−). In SF, the weaker DNRA, the stronger nitrification and denitrification, the higher soil available phosphorus (AP), and the lower nitrogen to phosphorus ratio (N/P) comprehensively suggested that SF was faced with a greater degree of N limitation. These results offer insights into the potential relationship between soil microbes and forest recovery, and aid in implementing proper forestry management.

Ectomycorrhizal fungal communities in the boundary between secondary broad-leaved forests and Japanese cypress plantations

ABSTRACT Belowground ectomycorrhizal (ECM) fungal communities are affected by the dominant tree species of aboveground vegetation. We investigated ECM-fungal communities in the boundary between secondary broad-leaved forests dominated by ECM trees and cypress plantations consisting of arbuscular trees. ECM root tips were collected from soil cores and seedlings at a small scale within 20 m of the boundary. We used molecular analysis of internal transcribed spacer regions of rDNA to identify ECM-fungal species. Of the 104 molecular taxonomic units detected from soil cores and seedlings, the estimated ECM-fungal species richness in broad-leaved forests was higher than that in the cypress plantations. More than half of the ECM-fungal species detected in cypress plantations were shared with adjacent broad-leaved forests. In particular, Russulaceae and Thelephoraceae were dominant in broad-leaved forests and cypress plantations. However, low-frequency occurrence taxa in broad-leaved forests were mostly absent in cypress plantations, at a distance of more than 10 m from the boundary. ECM-fungal species associated with seedlings tended to differ between broad-leaved forests and cypress plantations. Furthermore, Cenococcum geophilum shared soil cores and seedlings in both stands. These results indicated that ECM-fungal communities in cypress plantations were affected by adjacent broad-leaved forests, and this effect likely involved distance from the boundary.

Responses of seedling growth in subtropical secondary broad-leaved forest to nitrogen and phosphorus addition in Jiulian Mountain, China

An experiment with four treatments of control (CK), N addition (100 kg N·hm-2·a-1), P addition (50 kg P·hm-2·a-1) and N + P (100 kg N·hm-2·a-1 + 50 kg P·hm-2·a-1) were conducted to examine the responses of plant height, ground diameter, crown width, specific leaf area, and mortality of seedlings to N and P addition. Under P addition, growth rates of plant height and ground diameter of seedlings decreased significantly by 45.1% and 30.3%, respectively. Fertilization affected the mortality of main constructive tree species. N addition significantly increased seedling mortality of Castanopsis carlesii to 25.1%. Fertilization treatment significantly increased mortality of Castanopsis fargesii to 25.1%-31.3%, while N addition and P addition signi-ficantly reduced mortality of Schima superba and Machilus nanmu. Fertilization significantly decreased the importance value of S. superba and C. fargesii in the seedling community. N addition and P addition significantly increased the importance value of M. nanmu seedling. The combined N and P addition significantly decreased Shannon index and Simpson index of the seedling community. Seedling growth was mainly affected by soil ammonium, available phosphorus, total nitrogen, canopy openness, and specific leaf area. Seedling mortality was mainly affected by soil ammonium, available phosphorus and canopy openness. Synthetically, N and P addition affected seedling growth mainly by regulating soil nitrogen and phosphorus availability and changing leaf functional trait. It accelerated the death of ectomycorrhizal tree species (C. carlesii and C. fargesii), changed the importance value of constructive species in seedling community, reduced species diversity, and ultimately changed community structure of adult trees in subtropical secondary broad-leaved forest.

Medicinal Plant, Anoectochilus: Distribution, Ecology, Commercial Value and Use in North Vietnam

Background: Anoectochilus orchids have been widely used as medicine. However, it has been overharvested in nature because of high commercial values. This study aims at identifying distribution ranges and ecological characteristics of Anoectochilus orchids serving for sustainable development and describing traditional uses by ethnic people in Lai Chau Province, North Vietnam.
 Methods: Twenty-one plots of 100 m2 each (10 m × 10 m) were established for ecological survey and stand structures were analyzed for vegetation characteristics. While interviewing was applied to gather information on harvesting method, marketing, and medicinal uses.
 Results: Three Anoectochilus orchids (A. lanceolatus, A. calcareus, and A. setaceus) were found in Lai Chau Province, North Vietnam. These species distribute in both evergreen old-growth and secondary broadleaved forests, and mixed broadleaf-bamboo forest on the elevations of 996–2,134 m. They grow in forests with a high canopy cover of 67 m2 canopy area/ 100 m2 land and high cover (> 90% land) of low vegetation (< 2 m tall). It is believed that using the whole plant of Anoectochilus can treat hypertension and diabetes mellitus and improve the development of underdeveloped children. The folk uses include soaking in alcohol and boiled water for daily drinks like green tea, and consuming as a vegetable. The best harvesting season is during Autumn–Winter and fresh product is mainly marketed with the price of up to 100 U$D/1 kg fresh mass.
 Conclusion: A. lanceolatus, A. calcareus and A. setaceus are potential forest herbs for poverty reduction to ethnic communities in North Vietnam. The natural populations have been reduced remarkably because of overharvesting. Growing techniques are an urgent need for the conservation and sustainable development of such valuable orchids.

Diversity and seasonal changes in carabid assemblages of a mature, secondary and plantation forest mosaic in the Zhangguangcai Mountains in northeastern China

Abstract While China is promoting the re‐establishment of forests across the country on a globally unprecedented scale, the biodiversity harboured by the resulting secondary and plantation forests remains poorly understood. Here, we assess the carabid diversity at Zhangguangcai Mountains in northeastern China that comprise a unique mosaic of mature forest remnants, secondary forests and forest plantations. We located pitfall traps in five distinct forest types: mature conifer and mature mixed forest, secondary mixed forest, secondary broadleaved forest dominated by birch (Betula platyphylla) and poplar (Populus davidiana), and in larch plantations. We recorded 9073 carabid beetles representing 42 species, with richness, abundance and diversity of ground beetles all peaking in secondary broadleaved forests. Assemblages sampled in larch plantations were least species rich, but species extrapolation curves indicate a potentially high overall species richness. Carabid communities were clearly differentiated according to forest type, with larch plantations and secondary broadleaved forests containing beetle assemblages distinct from the other three forest types, while the mixed secondary and mature forest types harboured similar assemblages. Carabid communities also showed a clear seasonality in all forest types, with the plantation forest communities remaining distinctly different from the clustered communities of the mature and mixed secondary forest types throughout the year. Broadleaved secondary forest assemblages occupy an intermediate position throughout the sampling season.