[Objective]Understory plants are integral components of subtropical forests,which play a critical role in maintaining key ecosystem functions such as soil and water conservation,as well as supporting biodiversity conservation in subtropical forest ecosystems.Investigating the species composition,diversity characteristics,and driving mechanisms of understory plants across different forest types in subtropical regions can provide a solid scientific foundation for the conservation of regional understory biodiversity and the formulation of evidence-based forest management strategies.[Method]Six typical forest types in Lushan Mountain,including natural broad-leaved forest,natural coniferous-broadleaved mixed forest,planted Cryptomeria japonica forest,planted Cunninghamia lanceolata forest,planted Chamaecyparis obtusa forest,and planted Pinus taiwanensis forest,were selected as the research objects.Through plot investigation,the species composition,α/β diversity,and phylogenetic diversity of understory plants were analyzed,and a random forest model was employed to explore the key determinants of understory plant diversity.[Result]The coniferous-broadleaved mixed forest has the highest species richness,with 91 woody species in the shrub layer and 45 herbaceous species in the herb layer,and also contains the rarest and most endangered plant species(4 species),followed by the Cunninghamia lanceolata forest,while the Cryptomeria japonica forest has the lowest.The α-diversity indices of the shrub layer are generally higher than those of the herb layer across forest types,with the Cryptomeria japonica forest having the highest α-diversity index in the shrub layer.β-diversity also differs among forest types,with the highest Jaccard index in the shrub layer between the mixed conifer and broad-leaved forest and the Cunninghamia lanceolata forest,and the highest Jaccard index in the herb layer between the Cryptomeria japonica forest and the Chamaecyparis obtusa forest.Phylogenetic diversity of the shrub layer is higher than that of the herb layer in all six forest types,with the highest PD in the coniferous-broadleaved mixed forest,followed by the Cunninghamia lanceolata forest,and the lowest in the Chamaecyparis obtusa forest.Phylogenetic clustering is observed only in the shrub layers of the coniferous-broadleaved mixed forest,Cryptomeria japonica forest,and Cunninghamia lanceolata forest,and in the herb layer of the Pinus taiwanensis forest.Understory plant diversity is mainly influenced by stand type and annual precipitation;altitude has a significant effect on shrub diversity,while the ratio of carbon-to-nitrogen in soil exerts an extremely significant impact on herb diversity.[Conclusion]Shrub layer plant diversity exceeds herb-layer diversity in all forest types,with the highest understory plant diversity in the coniferous-broadleaved mixed forest and the lowest in the Chamaecyparis obtusa forest.Forest type,together with altitude,precipitation and other factors,synergistically shapes the understory plant diversity pattern.The higher diversity of the shrub layer than the herb layer is related to its competitive advantage in spatial resources.The coniferous-broadleaved mixed forest has prominent value in maintaining biodiversity and protecting national protected wild plants,which can provide reference for regional forest optimization and the transformation of planted forests.

ABSTRACT Herbarium collections are invaluable for understanding spatial distribution patterns and informing conservation management of biodiversity. However, herbarium collections of plant species in subtropical mountains have received limited attention. This study focuses on herbarium collections from plant species in nine subtropical mountains in China, aiming to identify patterns and drivers of collection bias, including geographic distribution, temporal trends, taxonomic focus, and collector contributions. Our results revealed that mountains in the northwest, for example, Mt. Lushan (LS) and Mt. Wugong (WG) exhibited higher herbarium collection density. However, mountains in the south, including Mt. Jiulian (JL) and Mt. Qiyun (QY), showed lower sampling efforts. Temporal distribution analysis elucidated historical consistencies and biases in herbarium collections, with collection peaks occurring during 1958–1959 and 1963–1965. Additionally, we found that the top 10% of collectors contributed more than half of the specimens. This research provides a comprehensive understanding of collection biases in subtropical mountains and proposes effective strategies for biodiversity conservation, such as strengthening collections in regions with high plant diversity, conducting targeted surveys in under‐sampled areas, and promoting collaboration among diverse collectors.

Global climate change has intensified the heterogeneity of precipitation regimes in subtropical regions, and the increasing frequency of extreme drought events poses a significant threat to biogeochemical cycling in forest ecosystems. Yet, the pathways by which reduced precipitation regulates deadwood decomposition and thereby influences soil nutrient pools remain poorly resolved. Here, we investigated a Cunninghamia lanceolata (Lamb.) Hook. plantation in subtropical China under ambient precipitation (CK) and precipitation reduction treatments of 30%, 50%, and 80%, systematically examining how reduced precipitation alters the chemical properties of deadwood substrates and, in turn, soil nutrient status. Our findings reveal that (1) as precipitation declined, soil water content decreased significantly (p < 0.01), while deadwood pH declined and total organic carbon (TOC), nonstructural carbohydrates (NSCs), and lignin content markedly accumulated (p < 0.01); (2) these shifts in deadwood chemistry affected feedback mechanisms, leading to the suppression of soil nutrient pools: extreme drought (80% reduction) significantly reduced soil TOC, dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) (p < 0.01) and inhibited N and P mineralization, whereas the 30% reduction treatment elicited a transient increase in soil microbial biomass carbon (MBC), indicative of microbial acclimation to mild water stress; and (3) principal component analysis (PCA) showed that the 80% reduction treatment drove lignin accumulation in deadwood, while the 30% reduction treatment exerted the greatest influence on soil DOC, TOC, and MBC; partial least squares path modeling (PLS-PM) further demonstrated that soil water content and deadwood substrate properties (pH, lignin, soluble sugars, TOC, C/N, and lignin/N) were strongly negatively correlated (r = −0.9051, p < 0.01), and that deadwood chemistry was, in turn, negatively correlated with soil nutrient variables (pH, TOC, DOC, MBC, TP, TN, and dissolved organic nitrogen [DON]; r = −0.8056, p < 0.01). Together, these results indicate that precipitation reduction—by drying soils—profoundly modifies deadwood chemical composition (lignin accumulation and NSC retention) and thereby, via slowed organic-matter mineralization, constrains soil nutrient release and accumulation. This work provides a mechanistic framework for understanding forest carbon–nitrogen cycling under climate change.

Study region: Jiangxi Province, China Study focus: Canopy interception is influenced by both structural and rainfall characteristics. yet, the relative contributions remain unclear due to their complex interactions. A process-based experimental study was conducted to quantify rainwater storage on canopies and assess how rainfall and crown structural characteristics influence key interception metrics: maximum and minimum canopy interception weight (Smax and Smin, g), interception per unit crown projected area (Cmax and Cmin, mm), and interception to gross precipitation ratio (Rmax and Rmin, %) for broadleaf and needleleaf species. New hydrological insights: Needleleaf species exhibit greater interception capacity than broadleaf species, due to morphological differences. Canopy interception is strongly influenced by both crown structure and rainfall parameters, with crown structure being critical for Cmax, Cmin, Smax, Smin, Rmax and Rmin, while rainfall characteristics primarily affect Rmax and Rmin. Three-dimensional canopy variables (leaf biomass density, leaf area density, leaf count density) have a stronger effect on Cmax and Cmin than two-dimensional variables (leaf area index, leaf biomass index, leaf count index). For Rmax, Rmin, Cmax and Cmin, leaf-related traits contributed more than branch-related traits. Within both leaf- and branch-related variables, their influence ranked as biomass, count, and area. Overall, Our findings indicate that tree characteristics exert a greater influence on rainfall interception than rainfall characteristics, whereas rainfall characteristics play a more role in shaping the interception ratio.

Altered precipitation regimes due to climate change influence plant–water interactions through shifts in soil moisture dynamics, highlighting the need for a mechanistic understanding of diverse water-use strategies and plant adaptations. In this study, we adopted an integrated approach combining measurements of stable hydrogen and oxygen isotopes in soil, groundwater, and xylem water, alongside sap flow and tree growth using dendrometers, to investigate the water-use strategies of Chinese fir (Cunninghamia lanceolata) under varying drought intensities. The experimental design included a control (C) and three precipitation reduction treatments (−30%, −50%, and −80%). This study analyzed data collected from both the wet and dry seasons of 2022, with precipitation exclusion devices installed and functioning since October 2021. The results indicated that during the wet season, Chinese fir primarily used shallow soil water (0–20 cm), with uptake proportions of 54.30%, 87.90%, 86.00%, and 63.70% under the C, −30%, −50%, and −80% treatments, respectively. In the dry season, as shallow soil water became increasingly scarce, water uptake gradually shifted toward deeper soil layers (40–60 cm), accounting for 49.30%, 79.10%, 68.50%, and 32.40%, respectively, and to groundwater sources, with 37.60%, 6.90%, 21.30%, and 61.50%, respectively. As expected, all precipitation reduction treatments reduced growth and water consumption (transpiration) compared with the C group. Notably, Chinese fir under the extreme drought treatment maintained adequate transpiration by relying heavily on groundwater throughout both seasons. This enabled increased growth during the wet season, though it also induced early growth cessation during the dry season. These findings suggest that Chinese fir exhibits substantial plasticity in its water acquisition strategies, allowing dynamic adjustment of water uptake between soil layers and groundwater sources depending on moisture availability. Our 1-year study demonstrates that Chinese fir can regulate water use and maintain radial growth under varying precipitation reduction treatments and seasonal conditions. Continuous long-term monitoring is essential to assess the sustained effects of drought on these ecohydrological processes.

Climate change, largely caused by elevated carbon dioxide (CO2) concentrations, is a driver of lasting disturbances that cause changes in forest ecosystem functioning. This study aimed to investigate how Japanese cypress (Chamaecyparis obtusa) and Japanese cedar (Cryptomeria japonica D. Don) plantations in the subtropical forests of China respond to disturbances in tree growth under climate change. In this study, 23 canopy gaps were selected from two species in the Lushan National Nature Reserve of Jiangxi Province, China. Increment cores were obtained from trees retained near the edges of gaps and within the forest. Tree-ring chronologies were established, and the basal area increment (BAI) was calculated. The growth averaging method was used to detect growth release and analyze two key parameters of tree radial growth: magnitude and time lag. Moving correlation analyses were used to assess the long-term relationship between tree growth and climate, and regression analyses were used to quantify the relationship between the BAI and atmospheric CO2 concentrations. Species characteristics, tree distance from the gap center, gap size, and elevation all influenced tree growth release which was greater for Japanese cedar than Japanese cypress, and decreased with increasing distance from the gap center. Diameter at breast height (DBH) and pre-release growth influenced the time lag in growth release. The time-lag effect was more significant with smaller DBH and pre-release growth and did not differ between the two species. The correlations among growth, temperature, and precipitation were altered by the microclimatic environment created by the gaps. The BAI of Japanese cypress and Japanese cedar responded quadratically with increasing CO2 concentration (Ca), and the BAI increased with rising Ca, peaking at 360–380 ppm, followed by a decreasing trend. Due to the effect of the disturbance, there was a BAI increase of approximately 400 ppm (2015) for trees at the gap edge. Growth characteristics were influenced by tree- and gap-level variables. Disturbance altered the link between tree growth and climate responses, increasing tree growth sensitivity to climatic influences, shifting the quadratic relationship between BAI and CO2 concentration, and providing growth potential to trees that crossed the CO2 tipping point.

Objective]This study aimed to theoretically support the scientific assessment of the carbohydrate-water coupling connection of Cryptomeria japonica.[Method]The water use efficiency（WUE） of Cryptomeria japonica was calculated using the tree-ring stable carbon isotope method in this study.Additionally,average temperatures （T）,precipitation （W）,average wind speeds （Ws）,solar radiation（Rs）,the drought index （SPEI,SPI,WI）,and other climate change-related indicators were used to analyze the WUE of Cryptomeria japonica and its adaptation to climate change.[Result]（1） From 1969 to 2018 the sequence of 13C values of Cryptomeria japonica tree rings in Lushan Mountain,Jiangxi Province of eastern China showed a downward trend;the variation range was -23.09‰ to -25.67‰,and the annua average was -24.55‰;the inter-annual value of Cryptomeria japonica WUE showed an upward trend;the variation range was 91.06 to 118.89μmol/mol,with an annual average of 102.37μmol/mol.（2） Correlation analysis revealed that the WUE of Cryptomeria japonica in Lushan Mountain was significantly correlated with the temperature in July,September to November of the previous year,February to June,and September to November of the current year,and significantly negatively correlated with the wind speed in July to December of the previous year and January to December of the current year.However,the solar radiation precipitation,SPEI,WI,and SPI of each month had no significant impact on the WUE of Cryptomeria japonica on Lushan Mountain.（3）The multiple regression model analysis showed that the WUE of Cryptomeria japonica on Lushan Mountain was mainly related to Ws 1 （wind speed in January of the curren year）,T 3 （average temperature in March of the current year）,T 9 （average temperature in September of the current year）,T -9 （average temperature in September of the previous year）,and Ws 12 （wind speed in December of the current year）.[Conclusion]T and Ws are the primary climatic variables affecting WUE of Cryptomeria japonica.The WUE of Cryptomeria japonica on Lushan Mountain is not significantly affected by W,Rs,or the drought indicators （SPI,SPEI and WI）.

The conversion of natural forests to planted forests has become a global trend, and the practice has wide-ranging effects on soil. This study aimed to explore the differences in soil water movement after the conversion of evergreen and deciduous broad-leaved mixed forests (natural forest, NF) to Chinese fir (Cunninghamia lanceolate (Lamb.) Hook.) plantations (CFP, 20–21 years old). Soil samples from five layers (0–5, 5–10, 10–20, 20–30, and 30–50 cm) were collected from NF and CFP before and after rainfall event in the Peng Chongjian watershed, Jiangxi Province. The physical properties of the soils, including the mean and coefficient of variation (CV) of soil moisture content and the soil particle composition, were determined in both forest types. The δD of soil water and the litter water-holding capacity were also measured. The results showed that the variation ranges of moisture content in each soil layer after the rainfall was 21.13%–49.40% in CFP and 21.33%–43.87% in NF. There were no significant differences in soil bulk density or porosity; the clay and silt contents were significantly increased in topsoil, while the sand was significantly decreased (P < 0.05). After the rainfall, soil water in CFP responded more promptly than NF. In the process of infiltration, the contribution of rainfall to soil moisture gradually decreased with increasing soil depth. Topsoil (0–5 cm) in NF responded promptly to rainfall, but the response showed a lag effect with the increase of soil depth. With the extension of infiltration time, the contribution of precipitation to deep soil gradually increased. The results showed that the soil did not degrade after the conversion of NF to CFP, a significant guiding result for plantation cultivation.

[Background] The redistribution of precipitation by forest has always been a hot spot and difficulty in hydrology research. Japanese cedar（Cryptomoria japonica） is the main afforestation tree species in Lushan Mountain, which plays an important role in ecological function such as soil and water conservation, atmospheric purification, and forest recreation. The purpose of this article is to explore the penetration rain process under different rainfall characteristics. [Methods] We did a research on monitoring data of real-time rainfall process of C. japonica forest in Lushan Natural Protection Area from April 2017 to September 2017 based on Lushan Ecosystem Observation and Research Station. And then we selected part of typical rainfall events（three different rainfall levels）, and analyzed time lag effects in different rainfall intensity. Through the 5-point method, the throughfall sample points were arranged on sample plot in forest, rainfall sample points were arranged on outside forest, and the data for both of them were collected through the auto rain gauge. [Results] In the rainy season of 2017, the rainfall characteristics of the Lushan Mountain were low（≤5 mm）, low rainfall intensity（≤2 mm/h） and short duration of rainfall（≤2 h）. During initial lag time from the beginning of rainfall outside the forest to the beginning of rainfall inside the forest, the initial lag time y decreased rapidly with the increase of the rainfall intensity x outside the forest, showing a power function relationship(y=0.656x -0.822 , R~2=0.823 4). The relationship between the initial lag time and the rainfall outside the forest was not obvious. The statistical results showed that the average rainfall intensity with positive canopy retention effect was smaller than that with the negative retention effect, and the most retention effect at ≤2 h and ＞8 h of rainfall duration was positive, and negative retention effect was evident at ＞4～8 h of rainfall reaching peak（mid rainfall duration）. [Conclusions] The characteristics of rainfall（rainfall intensity and duration） determine the process of throughfall, and then affect time lag effects of canopy. It can be found that in the process of rainfall, the effective time lag effects of canopy on rainfall mainly occur in the beginning and end of rainfall, while in the middle rainfall duration, the effect of canopy interception can almost be considered to be ignored, and the rainfall intensity inside the forest is greater than that outside the forest.

Precise assessment of soil organic carbon (SOC) storage requires understanding how vegetation and soil physicochemical properties differ in SOC fractions. Therefore, we aimed to analyze the dynamics of aggregate-associated, liable organic carbon (LOC) fractions corresponding to depth to clarify the effect of vegetation and soil properties on water stable aggregate (WSA) mineral adsorption in subtropical, red soil with five vegetation restoration regimes. The results showed that the large macro-aggregate fraction dominated the degraded red soil, which had the highest content of dissolved organic carbon (DOC). WSA-associated, easily oxidized organic carbon (EOC) varied from 6.26 to 20.02 g/kg and was not affected by vegetation types. Schima superba pure forest (SP) significantly increased DOC (0.38 g/kg on average) and particulate organic carbon (POC, 7.92g/kg on average), which had the highest biomass. Along with soil depth, WSA-associated POC declined, while exhibiting a growth trend with decreasing particle size, e.g., the highest POC was found in silt + clay fraction. The RDA ordination indicated that soil porosity and TN were the main soil parameters that explained the most variance. Meanwhile, the vegetation biomass, except for litter, were all significantly positively correlated with silt + clay fractions. Leaf biomass played the most important role on DOC in macro-aggregate with a 53.42% contribution. For aggregate-related POC, the largest contribution was from the interactions between branch biomass and pH (47.78%) followed by TN (35.1%) of micro-aggregate-related POC. Leaf biomass, silt + clay fractions, and TN can be used as indicators to evaluate the impact of vegetation restoration on WSA-associated SOC fractions. Broad leaved forest or combined with indigenous coniferous species was a better choice for SOC sequestration improvement in the study area.

Moso bamboo (Phyllostachys edulis) expansion into adjacent forests has been reported to alter the local water cycle. Transpiration is the most important component of the water budget. However, the changes in transpiration within Japanese cedar forests following moso bamboo expansion, as well as the primary factors driving these changes, remain unclear. In this study, we conducted an investigation in a mixed plantation of Japanese cedar and moso bamboo, a pure Japanese cedar forest, and a Japanese cedar forest after the removal of moso bamboo, from July 2017 to June 2018. We measured leaf area index (LAI), root biomass (Root), and sap flow density (Js). The annual transpiration of Japanese cedar significantly decreased from 521.48 mm in the pure Japanese cedar forest to 293.34 mm in the mixed plantation of Japanese cedar and moso bamboo. Likewise, the leaf area index decreased from 5.26 to 3.96, and the root biomass decreased from 252.78 g/m2 to 160.24 g/m2. In Japanese cedar forest, the transpiration in summer (189.47 mm) is greater than the sum of transpiration in autumn and winter (143.36 mm). The partial least squares path modeling (PLS-PM) analysis demonstrated that the decrease in root biomass was the direct cause of the reduced transpiration, while the decrease in leaf area index primarily led to the decline in root biomass. The results imply that the expansion of moso bamboo changed the above-ground canopy structure of Japanese cedar through the competition of above-ground mechanical damage, which reduced the leaf area and photosynthetic capacity of Japanese cedar, and then affected the below-ground root biomass, finally leading to the reduction of transpiration and the variation of ecohydrological process.

Nitrogen (N) leaching is a complex process regulating N exchange between the soil and aquatic ecosystems and may result in groundwater pollution, threatening ecosystem security. However, the mechanisms driving N leaching in subtropical forests have not been fully elucidated. Here, we present a quantitative analysis of vegetation-soil relationships in response to N leaching in a subtropical forest located in southern China. The results reveal that N leaching in runoff at lower simulated precipitation intensities (60 mm/h, 90 mm/h) and in sediment generated under higher intensities (120 mm/h, 150 mm/h) were significantly different across five vegetation restoration types. NH4+-N and TN were mostly lost through sedimentation, whereas NO3--N was primarily leached in runoff (80%-88%). N leaching was positively correlated with runoff, sedimentation rate, geometric mean diameter, mean weight diameter, and fine sediment particles (<0.25 mm), but negatively correlated with fractal dimension and coarser sediment particles. Random forest analysis demonstrated that runoff velocity was a critical driver of N leaching, suggesting that the impact of plant restoration on N loss should be considered. In order to minimize N leaching and resultant water pollution, guidelines informing the design of vegetation restoration projects in subtropical monsoon forests should emphasize the importance of planting Pinus elliottii. This result emphasized the importance of leaching erosion in forest ecosystem management and the need to understand the intricacies in the soil nitrogen sequestration potential at a regional scale in a changing climate.

Forest litter plays an important role in the hydrological process of an ecosystem, but the mechanism of inter-ception is not well understood and has not been fully evaluated. We conducted a process-based experiment under five simulated rainfall intensities. We directly quantified the interception of leaf litter and determined the effects of litter mass (MA), rainfall characteristics (RI) and leaf type (SP) on the interception of six common subtropical tree species, including two coniferous (Cunninghamia lanceolata (Lamb.) Hook. and Pinus massoniana Lamb.) and four broadleaf deciduous (Phoebe bournei (Hemsl.) Yang, Schima superba Gardn. et Champ., Liquidambar for-mosana Hance and Cinnamomum camphora (L.) Presl) species. The results demonstrated the following. (1) The interception process of litter can be divided into three phases: the wetting phase, the saturation phase, and the postrainfall drainage phase. The first phase of which arrived approximately 95% of the maximum interception storage (Cmax) and the duration was longer in broadleaf species than in coniferous species. This phase was significantly different among the species and rainfall characteristics, but it was not affected by litter mass. (2) Cmax and the minimum interception storage capacity (Cmin)of litter were not significantly different between the two forest types, but among the six species, especially between P.bournei and each of the two coniferous species, these values showed the greatest differences. (3) Cmax and Cmin increased significantly with litter mass and rain intensity. (4) Based on commonality analysis, the interaction between MA and RI largely outweighed the other variables in terms of their contribution to Cmax; however, MA surpassed all the other variables in its contribution to Cmin. We also found that the effects of the individual variables on Cmax and Cmin as well as their interactions, were significantly different; the three most influential variables for Cmax ranked in the descending order of their contributions were the interaction between MA and RI (41.07%), RI alone (23.69%), and MA (20.81%), and those for Cmin were MA alone (52.59%), the interaction between MA and RI (25.81%) and leaf types (14.58%). The quantitative and mechanistic explanations regarding the effects of leaf types, rainfall characteristics, litter mass and their interactions on litter Cmax and Cmin presented in this study are expected to increase our under-standing of the mechanism underlying litter interception.

Drought is one of the main factors limiting forest productivity, and thus greatly affects the carbon sink capacity of forests. Here we first chose two drought indices including standardized precipitation evapotranspiration index (SPEI) and self-calibrating Palmer drought severity index (scPDSI) to reflect and analyze the spatiotemporal patterns of drought in the subtropical China. Then, the validated CASA (Carnegie-Amer-Stanford Approach) model was applied to estimate forest net primary productivity (NPP) and further quantify the contributions of drought events and their characteristics on forest NPP. The results showed that drought events during 2000–2015 have resulted in a mean decline of forest NPP of 7.2%. Moderate or severe drought events reduced NPP more significantly than extremely severe drought events. In addition, there was 1–2 years of lagging in the NPP responses to drought, and the lagging time varied with forest types. Our study suggests that forest managers and local governments should pay more attention to the places with moderate and severe drought events, and take measures to avoid NPP decline within the 2 years after drought. Our study also provides data support for further identifying the contribution of drought to ecosystem carbon fluxes in the subtropical China.

This study aimed to investigate the effects of dynamic and static forest bathing (Shinrin-yoku) on the physiological and psychological health of males and females. Dynamic pre-test and post-test forest bathing was performed on 11 participants (5 males and 6 females) as a single group in a forest environment. In addition, a randomized controlled trial involving 20 participants (10 males and 10 females) was conducted to evaluate static forest bathing in both forest and urban environments. Various physiological indicators, including systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse, heart rate variability (HRV), and self-assessed psychological indicators such as profile of mood states, were measured. Dynamic forest bathing resulted in a significant increase in the natural logarithmic value of the high frequency (lnHF) of HRV and significantly decreased ratio of the natural logarithmic value of the low frequency (lnLF) to lnHF (lnLF/lnHF) of HRV. Static forest bathing not only had the effects of dynamic forest bathing but also significantly decreased the participants' SBP, DBP, and pulse. Both dynamic and static forest bathing enhanced human parasympathetic nervous system activity and reduced sympathetic nervous system activity, particularly affecting females. Negative mood state scores (tension, anger, fatigue, depression, and confusion) and total mood disturbance scores significantly decreased after forest bathing. In contrast, positive mood state (vigor) scores significantly increased, indicating an enhancement in positive mood. These improvements in mood were particularly pronounced in male individuals. Short-term exposure to a forest environment has positive effects on both physical and mental health of individuals. The extent of these improvements varied according to factors such as engagement in physical activity and gender.

Litterfall is an important part of the process of nutrient circulation and energy flow in forest ecosystems. Mountain forests are strongly eroded by running water in that the surface soil is thinner, and the terrain is complex and diverse. They are more sensitive to climate change, which will affect the ecological processes and carbon sink functions of forest ecosystems. Taking Lushan Mountain as an example, we studied the dynamic characteristics of litterfall components, seasonal changes in carbon input and the influencing factors of typical forest communities in the subtropics. The results showed that the total annual average litterfall components of evergreen broad-leaved forest (EBF) > artificial coniferous forest (ACF) > deciduous broad-leaved forest (DBF) > renew young forest (RYF), and that leaf litterfall is the first productivity in the litterfall components, and the peak of litterfall is mainly concentrated in spring and autumn, showing a single- or double-peaked change pattern. There was a linear relationship between the components of litterfall in the four forest communities and the stand factor, but the correlation degree R-2 was small. Overall, the results showed that the total amount of litterfall in the four forest communities was affected by canopy density and stand density. Light, temperature and water at different altitudes had different effects on the amount of litterfall, with excessive temperatures at lower altitudes likely to limit forest growth and development under adequate light and water, and the opposite was true at higher altitudes. The results of Pearson correlation analysis showed that EBF and DBF were negatively correlated with rainfall, that ACF and RYF were negatively correlated with temperature and rainfall, and that wind speed was positively correlated. The average annual carbon input size of the four forest communities was EBF > ACF > RYF > DBF, which may be related to environmental conditions and vegetation types, and the seasonal differences were arranged in order of spring > autumn > summer > winter. It can be seen that, considering performance under future climate change, EBF is more conducive to nutrient input and has good soil fertility maintenance ability.

[目的]分析林木不同生长阶段的空间结构特征有利于认识林分更新及其稳定性,为优化林分空间结构及自然植被恢复等提供参考依据.[方法]以庐山常绿阔叶林为研究对象,将林木生长划分为幼树(1 cm≤DBH<5 cm)、小树(5 cm≤DBH<10 cm)、中树(10 cm≤DBH<20 cm)和大树(DBH≥20 cm)4个阶段,选用混交度、大小比数、密集度、角尺度4种空间结构参数构建空间结构综合指数,采用熵权法进行权重赋值.[结果](1)幼树、小树、中树、大树的株数占林分总株数的比例分别为72.7％、16.8％、6.5％和4.0％,林分径级结构整体上呈倒"J"型.(2)幼树、小树、中树、大树的平均混交度分别为0.609、0.746、0.815和0.822,平均大小比数分别为0.545、0.268、0.132和0.089,平均密集度分别为0.852、0.895、0.871和0.842,平均角尺度分别为0.576、0.563、0.553和0.507;随着径级的增大,林木的混交、生长优势程度不断增大,密集程度先增大后减小,分布格局逐渐由聚集分布转变为随机分布.(3)小树、中树、大树的大小比数的权重均超过75.0％,优化其空间结构主要应调控其林木分化程度;幼树混交度和大小比数的权重分别为0.364和0.388,优化其空间结构则主要调控林木混交程度及分化程度.空间结构综合指数为大树(0.054)

Agricultural soils are major sources of greenhouse gases (GHGs) that related with intensive fertilizer input. Biochar is widely used to mitigate GHGs, which may interact with soil water content impacting GHG emissions. Camellia oleifera fruit shell (FS) and spent mushroom substrate (MS) are ideal biochar feedstocks. However, the impact of water content and biochar on soil GHG emissions has not been thoroughly understood. Here, we examined CH4 and N2O emissions from C. oleifera plantation soils as affected by biochar (derived from MS or FS, 1 g 25 g(-1) soil), water content (60%, 120%, 240% or 360% water holding capacity, WHC), and fertilization (control or chicken manure, CM 2.5 g 25 g(-1) soil). We determined the abundance of related microbial functional genes to obtain the underlining mechanisms. The results showed that higher N2O emissions occurred in soils with 120%WHC, due to increased abundance of AOA, AOB and nirS. MS or FS biochar differed in their effects on soil GHG emissions with different WHC. MS biochar was higher in pH, C/N and specific surface area, and mitigated more N2O emissions from soils with CM and 120%WHC relative to FS biochar (by 92.9% and 34.6%, respec-tively). MS biochar significantly decreased abundance of nitrification related functional genes (AOA, AOB) in soils with 120%WHC and CM, which explained the decrease in N2O emissions. However, MS biochar increased cumulative CH4 emissions from flooded soils via increase in mcrA abundance. Thereby, biochar feedstocks should be considered in CH4 and N2O mitigations from soils with different water contents.

Aims Nitrous oxide (N2O) plays an important role in global climate change. Plant expansion can alter soil nutrient cycling and greenhouse gas (GHG) fluxes but the effects of fine root litter mixing from plant expansion on litter decomposition, nutrient cycling, and GHG fluxes are poorly understood. Methods To evaluate the impacts of fine root litter mixing from plant expansion on GHG budgets, we conducted an in situ study over sixteen months in Japanese cedar (Cryptomeria japonica) plantations experiencing moso bamboo (Phyllostachys edulis) expansions. Litter decomposition and N2O production were quantified in a full-factorial complete-randomized design by comparing fine root litter of Japanese cedar, moso bamboo or their mixtures, with or without nitrogen (N) addition. Results We found that litter mixing accelerated decomposition, demonstrating a synergistic non-additive effect (19% increase in mass loss). This might have accelerated release of chemicals that inhibit microbial activities because litter mixtures had lower microbial biomass. Soil N2O emissions in the mixed litter treatment were 16.8% and 24.4% lower than those with only cedar or bamboo litter, respectively. N deposition promoted mass loss of mixed litter (28% increase in mass loss) and increased N2O emissions by 36.7%, 60.6% and 33.6% from cedar, mixed and bamboo litter treatments, respectively. Conclusion The expansion of moso bamboo promotes the return of soil nutrients, reduces N2O emissions, and potentially mitigates GHG emissions. However, with increasing N deposition in the future, moso bamboo expansion will likely contribute to global warming.

Moso bamboo expansion is common across the world. The expansion of moso bamboo into adjacent forests altered plant and soil characteristics. While the community structure of soil fungi and bacteria plays an important role in maintaining the function of forest ecosystems, changes in microbial community compositions remain unclear, limiting our understanding of ecological process changes following moso bamboo expansion. To explore changes in the community structure of soil fungi and bacteria in Japanese cedar plantations experiencing expansion of moso bamboo, Illumina NovaSeq high-throughput sequencing technology was used to elucidate changes in soil microbial communities as well as alteration in litter and soil chemical characteristics. The results showed that moso bamboo expansion decreased content of soil organic carbon, total nitrogen, litter carbon, and the carbon to nitrogen ratio as well as the number of bacterial operational taxonomic units (OTUs) at the genus level, the α-diversity Simple index, and the abundance of Acidobacteria, Chloroflexi, and Gemmatimonadetes. Moso bamboo expansion also increased soil NH4+-N, pH, while it decreased fungi OTUs at the phyla, class, order, family, and genus level. The expansion of moso bamboo into Japanese cedar substantially altered soil fungal and bacterial community structure, which might have implications for changes in the ecosystem element-cycling process. In the forest ecosystem and expansion management of moso bamboo, the types and different expansion stages of moso bamboo should be paid attention to, in the assessment of ecological effects and soil microbial structure.