Mountain National Forest Park Research Articles

The correlation between autumnal landscape colors and environmental factors and the analysis of ecological service functions in subtropical urban scenic forests

Background and objectivesUrban scenic forests are a main component of forest parks, and a quantitative study of the landscape color of urban scenic forests can provide a scientific reference for the planning of forest parks and the design of scenic forest management measures. The purpose of the study is to find the quantitative correlation between autumn landscape color and ecological service functions and to obtain the important influencing factors.Materials and methodsThis study focuses on Purple Mountain National Forest Park in Nanjing as a case study area and uses forest resource survey data from Purple Mountain National Forest Park in 2020, autumn landscape color photograph data from Purple Mountain National Forest Park in 2020, and digital elevation model data as the main information sources. The correlation between two ecological functions of above-ground biomass (AGB), tree species diversity (TSD), and influencing factors (including color factors, stand factors, and terrain factors) were both analyzed by Pearson correlation analysis. Then, multiple linear regression (MLR) and random forest (RF) methods were used to perform the quantitative relationship between the functions.ResultsThe results show that, in the established quantitative models of AGB, with TSD as the dependent variable, the correlation coefficients of the MLR model are both above 0.784, while the correlation coefficients of the RF model are all above 0.872. Moreover, the brightness value of the main color (BRI), the number of yellow-green blocks (NYG), and the number of yellow blocks (NY) have important effects on the two ecological service functions.ConclusionIn conclusion, there are complex non-linear relationships between the ecological service functions of AGB, TSD, and influencing factors, and the landscape color can reflect the ecological function of the scenic forest to some extent. In addition, stand factors and color factors have important effects on the ecological function of AGB. Color factors and terrain factors have important effects on the ecological function of TSD. BRI, NYG, and NY have important effects on the two ecological functions. Finally, this quantitative method has universal applicability in the temperate zone, warm temperate zone, and subtropical zone of China.

Analyzing temporal and spatial forest carbon storage using Google Plus Code: a case study of Zijin Mountain National Forest Park, China.

It is always a challenging job to compare forest resources as there is not a standardized spatial unit with location information. Google Plus Code, the newest alphanumeric geocoding system, uses 20 specifically selected letters and numbers to assign a unique global ID to every cell at different levels of a hierarchical grid system which is established based on latitude and longitude. It can be used as a standardized, unique global geospatial unit to segment, locate, quantitate, evaluate, and compare natural resources with area, boundary, and location information embedded. For this proof-of-concept case study, forest inventory data from 1987, 2002, and 2019 for the Zijin Mountain National Forest Park in Jiangsu Province, China was analyzed based on Google Plus Code grid/cell. This enabled the quantification of carbon storage at each cell allowing for the comparison of estimated carbon storage at same or different locations over time. This methodology is used to quantify the impacts of changing forest conditions and forest management activities on carbon storage with high spatial accuracy through the 32-year study period. Furthermore, this technique could be used for providing technical support and validation of carbon credit quantification and management.

Dynamic Simulation and Tradeoffs and Synergies of Ecosystem Service Value in Metropolitan Suburbs Using the PLUS Model

INTRODUCTION: Due to rapid economic development and continuous human activities, land use changes in the suburbs of metropolitan areas are drastic, which in turn affects the balance of ecosystem functions. Analyzing and predicting the ecological service value characteristics and trade-offs in rapidly urbanizing regions is of great significance for promoting high-quality regional development.AIM: This study attempts to reveal the trade-off and synergistic characteristics between the internal values of ecosystem services in suburban metropolitan areas under the influence of rapid urbanization.METHODS: Based on the patch-generating land use simulation (PLUS) model, simulated the land use changes in Xinzheng City under multiple scenarios in 2030, combined with methods such as equivalent factor method and spatial autocorrelation analysis，estimating, and predicting the ecosystem service value and its trade-off synergy relationship in Xinzheng City from 1980 to 2030.RESULTS: The value of ecosystem services in Xinzheng City continues to decline, hydrological regulation and soil conservation are the most important ecosystem service functions, under the scenario of farmland protection, ESV shows a stable growth trend. The synergistic relationship between various functions of ESV is significant, the Shizu Mountain National Forest Park, Shuangji River and other high agglomeration areas, as well as the Airport Economic Zone and Nanlonghu Town and other low agglomeration areas, all show a synergistic relationship, with only a portion of the southern side of the main urban area of Xinzheng showing a balancing relationship.CONCLUSIONS: Our findings can scientifically identify the environmental advantages of ecological sustainable development in Xinzheng City, and transform them into development advantages, providing provide strong technical support for the spatial ecological restoration and ecological security pattern construction of metropolitan suburbs.

Analysis of Eco-Environmental Quality of an Urban Forest Park Using LTSS and Modified RSEI from 1990 to 2020—A Case Study of Zijin Mountain National Forest Park, Nanjing, China

Evaluating the long-term urban forest ecological environmental quality (EEQ) and analyzing the drivers of its spatiotemporal changes can provide a scientific basis for making long-term urban forest planning decisions. Taking into account the characteristics of urban forest parks with low area proportions of construction land and bare land, high vegetation coverage, and serious forest disturbances, we constructed a modified urban forest park EEQ evaluation index based on a remote sensing ecological index named MRSEI, which is composed of the Landsat enhanced vegetation index (EVI), wetness, land surface temperature (LST), and forest disturbance index (FDI). We selected the Nanjing Zijin Mountain National Forest Park as the study area, used landsat time series stack (LTSS) remote sensing images from 1990 to 2020 as the main data source, and adopted the suggested modified MRSEI, the Theil-Sen median method, and the Hurst index to evaluate the EEQ to analyze its spatiotemporal variations and its driving factors in the study area. The main research results were as follows: (1) the EEQ of Zijin Mountain showed an up-and-down, overall slowly increasing trend from 1990 to 2020, while the spatial auto-correlation coefficient showed an overall decreasing trend; (2) the area percentage of the EEQ-persistent region accounted for 78.69%, and the anti-sustainable region accounted for 21.31%; (3) the spatial centers of the EEQ in the study area were mainly concentrated on the middle and upper part of the southern slope of Zijin Mountain, moving southward from 1990 to 2020; (4) the analysis of drivers showed that climate factors, forest landscape structure, forest disturbances, and forest growth conditions were the main driving factors affecting the EEQ in the study area. These results provide a research framework for the analysis of EEQ changes over a long-term period in the urban forest parks of China.

Research on Estimating and Evaluating Subtropical Forest Carbon Stocks by Combining Multi-Payload High-Resolution Satellite Data

Forest carbon stock is an important indicator reflecting the structure of forest ecosystems and forest quality, and an important parameter for evaluating the carbon sequestration capacity and carbon balance of forests. It is of great significance to study forest carbon stock in the context of current global climate change. To explore the application ability of multi-loaded, high-resolution satellite data in the estimation of subtropical forest carbon stock, this paper takes Huangfu Mountain National Forest Park in Chuzhou City as the study area, extracts remote sensing features such as spectral features, texture features, backscattering coefficient, and other remote sensing features based on multi-loaded, high-resolution satellite data, and carries out correlation analyses with the carbon stock of different species of trees and different age groups of forests. Regression models for different tree species were established for different data sources, and the optimal modeling factors for multi-species were determined. Then, three algorithms, namely, multiple stepwise regression, random forest, and gradient-enhanced decision tree, were used to estimate carbon stocks of multi-species, and the predictive ability of different estimation models on carbon stocks was analyzed using the coefficient of determination (R2) and the root mean square error (RMSE) as indexes. The following conclusions were drawn: for the feature factors, the texture features of the GF-2 image, the new red edge index of the GF-6 image, the radar intensity coefficient sigma, and radar brightness coefficient beta of the GF-3 image have the best correlation with the carbon stock; for the algorithms, the random forest and gradient-boosting decision tree have the better effect of fitting and predicting the carbon stock of multi-tree species, among which gradient-boosting decision tree has the best effect, with an R2 of 0.902 and an RMSE of 10.261 t/ha. In summary, the combination of GF-2, GF-3, and GF-6 satellite data and gradient-boosting decision tree obtains the most accurate estimation results when estimating forest carbon stocks of complex tree species; multi-load, high-resolution satellite data can be used in the inversion of subtropical forest parameters to estimate the carbon stocks of subtropical forests. The multi-loaded, high-resolution satellite data have great potential for application in the field of subtropical forest parameter inversion.

Landscape Health Assessment of Suburban Forest Park: A Case Study Based on Multiple Sampling Units and Functional Characteristics

Assessing the landscape health of suburban forest parks is a prerequisite for achieving the dual objectives of forest resource conservation and recreational services. However, studies that analyze landscape health in suburban forest parks at a landscape scale by subdividing the landscape into multiple sampling units and adopting a multi-functional perspective have been limited. This study focuses on Xiqiao Mountain National Forest Park and establishes a landscape classification system and indices, taking into account its multifunctionalities. The study employs the entropy weight method to determine indicator weights and utilizes grid analysis and spatial interpolation to analyze the spatial distribution of landscape health under multiple sampling units and functionalities, along with the differences in its impact and influencing factors. The results indicate that: (1) regions with “very poor” and “poor” landscape health grades under multiple sampling units and functionalities exhibited a sheet-like distribution pattern, covering approximately 69.46% to 98.86% of the total area. In contrast, regions with “very good” and “good” grades are primarily located in block-like or linear patterns in the northern, central, and southern regions of the park, accounting for approximately 1.07% to 17.20% of the total area. (2) The area ratios of “very good” and “good” landscape health grades for recreational landscapes under varying sampling units were consistently higher than those of the same grades for eco-conservational landscapes, with a 5.03%–15.43% difference. This suggests a greater emphasis on recreational functionality. (3) The impact of three different sampling unit sizes on the landscape health of Xiqiao Mountain National Forest Park under multifunctionalities is not significantly different; however, the forest/non-forest area ratio and quantity ratio are vital factors influencing its landscape health. The landscape health assessment results, considering multiple sampling units and functionalities in this study, serve to provide technical method support and practical case references for the planning, construction, and management decision-making of suburban forest parks.

Forests on the move: Tracking climate‐related treeline changes in mountains of the northeastern United States

AbstractAimAlpine treeline ecotones are influenced by environmental drivers and are anticipated to shift their locations in response to changing climate. Our goal was to determine the extent of recent climate‐induced treeline advance in the northeastern United States, and we hypothesized that treelines have advanced upslope in complex ways depending on treeline structure and environmental conditions.LocationWhite Mountain National Forest (New Hampshire) and Baxter State Park (Maine), USA.TaxonHigh‐elevation tree species—Abies balsamea, Picea mariana and Betula cordata.MethodsWe compared current and historical high‐resolution aerial imagery to quantify the advance of treelines over the last four decades, and link treeline changes to treeline form (demography) and environmental drivers. Spatial analyses of the aerial images were coupled with ground surveys of forest vegetation and topographical features to ground‐truth treeline classification and provide information on treeline demography and additional potential drivers of treeline locations. We used multiple linear regression models to examine the importance of both topographic and climatic variables on treeline advance.ResultsRegional treelines have significantly shifted upslope over the past several decades (on average by 3 m/decade). Gradual diffuse treelines (characterized by declining tree density) showed significantly greater upslope shifts (5 m/decade) compared to other treeline forms, suggesting that both climate warming and treeline demography are important correlates of treeline shifts. Topographical features (slope, aspect) as well as climate (accumulated growing degree days, AGDD) explained significant variation in the magnitude of treeline advance (R2 = 0.32).Main ConclusionsThe observed advance of treelines is consistent with the hypothesis that climate warming induces upslope treeline shifts. Overall, our findings suggest that gradual diffuse treelines at high elevations may be indicative of climate warming more than other alpine treeline ecotones and thus they can inform us about past and ongoing climatic changes.

Temporal and spatial changes in rhizosphere bacterial diversity of mountain Rhododendron mucronulatum.

To better conserve the ecology of the wild Rhododendron mucronulatum range, we studied the rhizosphere microenvironment of R. mucronulatum in Beijing's Yunmeng Mountain National Forest Park. R. mucronulatum rhizosphere soil physicochemical properties and enzyme activities changed significantly with temporal and elevational gradients. The correlations between soil water content (SWC), electrical conductivity (EC), organic matter content (OM), total nitrogen content (TN), catalase activity (CAT), sucrose-converting enzyme activity (INV), and urease activity (URE) were significant and positive in the flowering and deciduous periods. The alpha diversity of the rhizosphere bacterial community was significantly higher in the flowering period than in the deciduous period, and the effect of elevation was insignificant. The diversity of the R. mucronulatum rhizosphere bacterial community changed significantly with the change in the growing period. A network analysis of the correlations revealed stronger linkages between the rhizosphere bacterial communities in the deciduous period than in the flowering period. Rhizomicrobium was the dominant genus in both periods, but its relative abundance decreased in the deciduous period. Changes in the relative abundance of Rhizomicrobium may be the main factor influencing the changes in the R. mucronulatum rhizosphere bacterial community. Moreover, the R. mucronulatum rhizosphere bacterial community and soil characteristics were significantly correlated. Additionally, the influence of soil physicochemical properties on the rhizosphere bacterial community was larger than that of enzyme activity on the bacterial community. We mainly analyzed the change patterns in the rhizosphere soil properties and rhizosphere bacterial diversity of R. mucronulatum during temporal and spatial variation, laying the foundation for further understanding of the ecology of wild R. mucronulatum.

B&B Economy Lights up Rural Revitalization

"Anyuan County is not far away, the scenery is in front of you." Relying on the scenic spot of the Sanbai Mountain National Forest Park, Anyuan County is a vigorously developing tourism, furthermore, it reasonably promotes the development of rural B&B economy, which will add bricks to the road of rural revitalization of it. But at present, the rural B&Bs in Anyuan only rely on repairing houses and Increase beds, which lack of characteristics. Therefore, through the branded growth of B&B, the development of "B&B+" experiential integrated leisure industry, the integration of rural culture construction and propaganda, agriculture and traditional handicrafts, to make the maximum use of existing ecological tourism resources in Anyuan, creating an innovative development path of B&B with temperature and sentiment.

Construction of wetland ecosystem model framework in Phoenix Mountain National Forest Park Nature Reserve in Harbin and application case studies

Context The wetland ecosystem of Harbin Fenghuangshan National Forest Park Nature Reserve is fragile. Aims To establish a scientific and reasonable model framework for dynamic monitoring and ecological health assessment of wetlands, which is conducive to early warning, protection and management of wetland ecosystems. Methods On the basis of the full consideration of energy flow, material circulation, ecological environment and interspecific relationship, this paper proposed an ecosystem model framework. The pressure–state–response (PSR) model was used to build the evaluation index system of wetland-ecosystem health in Harbin Fenghuangshan National Forest Park. The data of each indicator are extracted and standardised through the analytic hierarchy process. Key results The results showed that the ecosystem pressure index of Harbin Fenghuangshan National Forest Park wetland was 0.52, indicating that it is in a subhealth state. The degree of health was 0.603, indicating a good condition. The comprehensive response index was 0.615, which was a positive response. The comprehensive degree of health was 0.577, indicating a subhealth state. Conclusion and implications The management and protection of wetland ecosystem in Harbin Fenghuangshan National Forest Park need to be strengthened urgently.

Components and mechanism of health impact of multisensory therapeutic landscape in tourism destinations based on the new health geography perspective:A case study of Nanjing Purple Mountain National Forest Park

Components and mechanism of health impact of multisensory therapeutic landscape in tourism destinations based on the new health geography perspective:A case study of Nanjing Purple Mountain National Forest Park

A dataset of the ecosystem service assessment in Mao’er Mountain National Forest Park during 2018–2019

Mao’er Mountain is a typical area of natural secondary forest with strong spatial heterogeneity. As a result, the scientific assessment of ecosystem service function value in Mao’er Mountain can provide data support for researches on the decision-making for forest management and the relation between supply and demand for natural forests. This paper provides a dataset of six categories of ecological indicators in Mao’er Mountain, including water conservation, soil conservation, carbon fixation and oxygen release, nutrient accumulation, atmospheric purification, biodiversity conservation, which are assessed based on the Specifications for Assessment of Forest Ecosystem Services in China (LY/T 1721-2008). The raw data mainly include GF-1 remote sensing data, meteorological data, forest resource inventory data for management, etc. The data accuracy is strictly ensured through a series of processes such as vectorization, correction, and registration. The dataset in this paper includes the physical and value quantities of 18 specific ecological indicators in the ecosystem service assessment system. The data can be divided into two types: monthly data and yearly data according to the time resolution with unified spatial resolution of 16 m. During the process of index calculation, we strictly screened and controlled the input data and model parameters in this study, so as to ensure the reliability of the dataset through comparison and verification. This dataset covers most of the indicators in the forest ecosystem service assessment system, which can provide fine-grained data support for the study on natural secondary forest in cold temperate zones in China.

Cohnella mopanensis sp. nov., a new Gram-negative bacterium isolated from soil in Xinping Mountain National Forest Park.

A Gram-stain-negative, aerobic, rod-shaped bacteria strain, named YIM B01951T, was isolated from a forest soil sample collected from Mopan Mountain National Forest Park, Xinping City, Yunnan Province, southwest PR China (101°58'06" N, 23°03'02" E). Growth occurred at 15-40°C (optimum, 30°C), pH 5.0-8.0 (optimum, pH 6.5) and with up to ≤ 3.0% (w/v) NaCl on Nutrient Agar plates. The results of 16S rRNA gene sequence similarity analysis showed that strain YIM B01951T was closely related to the type strain of Cohnella arctica M9-62T (96.5%) and Cohnella lupini RLAHU4BT (96.3%). YIM B01951T contains anteiso-C15:0 and iso-C16:0 as the major cellular fatty acids; the main polar lipids are diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), lysylphosphatidylglycerol (PGL) and five aminophospholipids (APL). The MK-7 is the major respiratory quinone and the DNA G + C content is 49.2mol%. Based on these phenotypic, chemotaxonomic and phylogenetic analyses, strain YIM B01951T is considered to be a novel species of the genus Cohnella, and named Cohnella mopanensis sp. nov. The type strain is YIM B01951T (= NBRC 115331T = KCTC 43370T).

Microvirga terricola sp. nov. and Microvirga solisilvae sp. nov, isolated from forest soil.

Two Gram-staining-negative, aerobic and rod-shaped strains, designated c23x22T and sex2T, were isolated from forest soil collected from Chebaling National Nature Reserve in Guangdong Province and Limu Mountain National Forest Park in Hainan Province, P. R. China, respectively. Phylogenetic analyses based on 16S rRNA gene sequences revealed that they belonged to the genus Microvirga, and strain c23 x22T was most closely related to 'Microvirga alba' KCTC 72385, while strain sex2T showed close relationship with Microvirga guangxiensis CGMCC 1.7666T. The average nucleotide identity and digital DNA-DNA hybridization values between strains c23 x22T and sex2T and their close relatives, 'M. alba' KCTC 72385 and M. guangxiensis CGMCC 1.7666T, were all below the threshold values for species delimitation. The predominant quinones of the two novel strains were ubiquinone 10, and the major fatty acids contained C19:0 cyclo ω8c and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). Their predominant polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. The phenotypic, genotypic and chemotaxonomic analyses clearly supported that strains c23 x 22T and sex2T represent two novel species of the genus Microvirga, for which the name Microvirga terricola sp. nov. (type strain c23 x 22T = GDMCC 1.1700T = KCTC 62432T) and Microvirga solisilvae sp. nov. (type strain sex2T = GDMCC 1.1651T = KACC 21311T) are proposed, respectively.

Influence of Tourism Disturbance on Soil Microbial Community Structure in Dawei Mountain National Forest Park

This research aimed to reveal the response characteristics of soil microbial community structure to different degrees of tourism disturbance. To explore the soil microbial community structure’s response mechanism, we set up continuous plots with different interference intensities: high disturbance, middle disturbance, and the control area. We collected 0–10 cm topsoil in all plots and used Illumina MiSeq high-throughput sequencing method to obtain and analyze the response characteristics of soil microbial community composition and structure under different tourism disturbances. These results were then combined with alpha diversity and environmental factors to explore the microbial response mechanism. In the tested soil, Acidobacteria, Chlorocurve, and Proteobacteria were the main bacterial phyla, while Basidiomycota and Ascomycota were the main fungal phyla. Based on the phylum, the relative abundance of the microbial community between the interference groups was compared using a significance test, with significant differences found between the interference groups in the phyla Chloroflexus, GAL15, Rokubacteria, and Blastomonas (p < 0.05). The relative abundance of the dominant phyla in the fungal community was significantly different among the groups (p < 0.05). A principal component analysis of the soil microbial community structure suggested that the soil microbial community structure was significantly different for different interference levels.

Tourists’ perceptual presentation of national forest park——A case study of Wujin mountain national forest park

ABSTRACT Tourists’ perceptions are always presented in a certain way, and social media platforms play a role in this regard. Using Rost and Nvivo for frequency extraction and multiple encoding, we analysed social media comments about the Wujin Mountain National Forest Park. The results reveal five types of perceived tendencies: “complaint suggestion”, “emotion express”, “consulting description”, “travel experience description”, and “value judgment”; and three kinds of platform features, one being “consulting–travel experience”, the other two, namely “value judgment–positive value” and “self-expression–complaint”.There are three categories of perceptual content: tourism resources are the most, followed by experience evaluations and traffic information. Presentation in social media is the basic demand of tourists; the National Forest Park perception is still at the entertainment level and the ecology of forests has not been highlighted. Communitas is not only reflected in the activity, but also on media platforms, and ultimately shapes the overall image of the National Forest Park. We hope that this study can provide suggestions for innovative development of the National Forest Park.

Effects of Different Site Conditions on the Concentration of Negative Air Ions in Mountain Forest Based on an Orthogonal Experimental Study

The negative air ions (NAI) in a forest play an important and positive role in promoting the health of people using the forest for recreation. The purpose of this study was to explore the environmental characteristics that can effectively represent high concentrations of NAI in mountain forests to help the recreational users to seek out sites with high NAI concentrations for personal health reasons. In order to achieve this goal, we selected the mountain forest of Taibai Mountain National Forest Park, Shaanxi Province, China, as the research object and adopted an orthogonal experimental design with three factors and three levels to study the effects of terrain, altitude, and forest canopy density on the forest NAI concentrations. The results show that obvious peak–valley fluctuation occurs during 6:31 a.m. to 18:30 p.m., with the highest concentration of NAI at 8:00 a.m. (Average: 163 ions/cm3) and the lowest at 16:00 p.m. (Average: 626 ions/cm3). The altitude (p < 0.01) and canopy density (p < 0.05) were found to significantly affect NAI concentrations. The combination of site conditions in the mountain forest observed to have the highest NAI concentrations was valley topography, low altitude, and high canopy density. In addition, the highest NAI concentration was between 14:00 p.m. and 16:00 p.m., under this combination, which was thus identified as the most suitable time for health-promotion activities in mountain forests. The results provide insights into the NAI concentration characteristics and variations, along with identifying important environmental factors for the selection of health-promotion activities in mountain forests.

Functional traits change but species diversity is not influenced by edge effects in an urban forest of Eastern China

Forest edges have significant effects on plant species and trait compositions. However, most current studies on edge effects are based on natural forests, and studies on edge effects in urban forests are still limited. Here, we set up 50 survey plots in Wuchao Mountain National Forest Park, an urban forest of Hangzhou, China. We tested how species composition changed with distance from the forest edge. Specifically, we investigated dispersal-related traits for 86 species, and analyzed trait composition changes with distance from the forest edge. The NMDS analysis revealed a significant difference in species composition between forest edge and interior, but species richness and functional diversity remain unchanged. However, single traits showed higher divergence than expected. The percentage of fleshy-fruited species declined with distance from the edge, but plant abundance of mammal-dispersed and animal-dispersal seed mass was increased. The different trend in seed size of different dispersal mode and seed mass from edge to the interior within the community may be related to the loss of mammal-dispersed plant species at the forest edge. This suggests that edge effects have a high influence on functional traits in urban forests, but not on species diversity. Edges had significant effects on animal-dispersed species and trait composition of plant communities. Our study highlights the importance of maintaining forest integrity by protecting interior habitats in urban regions. We also recommend reducing the creation of new edges and increasing the buffer area for biodiversity conservation.

A climate sensitive mixed-effects diameter class mortality model for Prince Rupprecht larch (Larix gmelinii var. principis-rupprechtii) in northern China

Forest mortality is an important variable commonly included as one of the predictors in the growth and yield models that are the fundamental decision-making tools in forest management. The existing forest mortality models for Larch (Larix gmelinii var. principis-rupprechtii) forest, which plays key roles in maintaining forest ecosystem functions and reducing atmospheric carbon concentration through the sequestration, are based on the traditional modeling methods, and these models do not account for the effects of climate on the forest mortality. Developing climate sensitive mortality models are useful for formulating effective forest management strategies in the context of climate change. We developed the diameter class mortality models using the data of 102 temporary sample plots distributed across the Guandi Mountain National Forest Park and Wutai Mountain Boqiang State-owned Forest Farm in the Shanxi Province of northern China. Four commonly used mortality functions were used to fit the data. Among many climatic and dendrometric variables evaluated, number of trees per diameter class (NC), mean annual precipitation (MAP); median diameter class (MDC), and mean temperature difference (DT) contributed significantly highly to the mortality variations. Then, these variables were selected as predictors to develop the two-level nonlinear mixed-effects mortality models applicable to the diameter class levels. The random effects at the levels of both the sample plots and stands with different site quality (blocks) were taken into account to build the models. Compared to other three models derived from the Poisson; Zero-inflated Poisson; Hurdle Poisson functions, the two-level Logistic mixed-effects mortality model better explained the effects of climate variables on the forest mortality of Larch. Tree mortality increased with increasing NC and MAP, however, MDC and DT had the opposite effects with diameter class increasing. Modeling the random effects at the block-level alone led to significantly high correlations among the residuals, and correlations were significantly reduced when the random effects were modeled at both the block- and sample plot-levels. Excessive rain during the growing season decreased the rate of tree mortality, especially for diameter classes with high number of trees. Findings from this study can be combined with the knowledge of the adaptive management to reduce the risks and uncertainties associated with forest management decision.

Variation of subtropical forest soil microbial biomass and soil microbial community functional characteristics along an urban-rural gradient

Soil microorganisms, which are sensitive to environmental changes, affect soil nutrient cycling and play an important role in the biogeochemical cycling. To understand the changes of soil microorganisms in subtropical forest across the urban-rural environmental gradient, we analyzed the differences in soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial community functional diversitiy in Dashu Mountain National Forest Park (urban forest), Zipeng Mountain National Forest Park (suburban forest) in Hefei and Wanfo Mountain(rural forest) in Luan City. Results showed that soil MBC followed an order of rural natural forest (115.07 mg·kg-1) > suburban forest (101.68 mg·kg-1) > urban forest (82.73 mg·kg-1), soil MBN followed an order of rural natural forest (57.73 mg·kg-1) > urban forest (31.57 mg·kg-1) > suburban forest (29.01 mg·kg-1), soil microbial metabolic activities (AWCD), McIntosh index (U) were shown as rural natural forest > suburban forest > urban forest. The main carbon sources used by soil microbial communities in those forests were carboxylic acids, amino acids and carbohydrates, with weak utilization capacity for polyamines and polyphenols. The utilization capacity of soil microorganisms to amino acids, carboxylic acids, polymers and polyphenols followed the order of rural natural forest > suburban forest > urban forest. There were significant spatial variations in the functional characteristics of soil microbial communities under urban-rural environmental gradient, with Tween 80 and β-methyl-D-Glucoside being the characteristic carbon sources as the influencing factors. Soil pH was significantly positively correlated with the microbial McIntosh index and AWCD value, while soil ammonium nitrogen (NH4+-N) showed a significant positive correlation with microbial Shannon diversity index and AWCD value. There was a negative correlation between the microbial Simpson index and soil nitrate nitrogen (NO3--N). Soil pH, NH4+-N and NO3--N were the main factors affecting diversity index of microbial communities. The results suggested that there were significant differences in microbial community characteristics of forest soil in urban-rural environmental gradient forests, and that the metabolic potential and functional diversity of soil microbial community in urban forests were weaker than that of natural forests.