Objective: This study aims to clarify the trade-offs between light, nitrogen and water use efficiency (RUEs) in the leaves of the understorey shrub Rhamnus parvifoliaand their environmental regulation mechanisms. Method: We analyzed the seasonal dynamics of intrinsic water use efficiency (WUE_i), nitrogen use efficiency (NUE) and light use efficiency (LUE) as well as the trade-offs among RUEs of a dominant understory shrub, R. parvifolia, leaves through season-long in-situ measurements of the light response curve and leaf functional traits along with simultaneous environmental measurements from June to October, 2021 in Miyun, Beijing, China. Result: 1) The result showed that the maximum WUE_i, NUE, and LUE in growing season fluctuated with values of 107.3 μmol·mol^?1, 18.35 μmol·g^?1s^?1, and 0.087 mol·mol^?1, respectively, with coefficient of variation (CV) being 24.91%, 39.12%, and 12.6%. 2) In the middle of the growing season, under the wet condition with relative extractable soil water (REW) greater than 0.4, there were higher NUE and lower WUE_i. The NUE had opposite trend to WUE_i (P < 0.05) and varied synergistically with LUE ( P < 0.05). 3) The WUE _i was positively correlated with leaf mass per unit area (LMA) (P < 0.05) and negatively correlated with transpiration rate (Tr, P < 0.05), while NUE was negatively correlated with LMA and leaf thickness (LT, P < 0.05) and positively correlated with Tr ( P < 0.05). Increases in air temperature ( T_a), photosynthetically active radiation (PAR) and diffuse radiation (R_dif) all contributed to increased LUE (P < 0.05). Conclusion: It has been found that WUE_i and NUE are decoupled from soil water content and closely relate to LMA and Tr in wet period and limited light. Increasing radiation and T_a promotes the light utilization efficiency of leaf, and diffuse radiation raises the photosynthetic capacity of leaf. There is a trade-off between RUEs. The NUE and WUE_i can not simultaneously maximize in the growing season, but under wet condition and low light, NUE and LUE change in the same direction, both fluctuating in the middle of the growing season and gradually decrease at the end of the growing season. The results of this study are important additions to the in-depth understanding of the adaptation strategies of temperate plant communities under climate change.

Objective: This stusy aims to examine the trade-offs between leaf traits, including chemical-, structural- and photosynthetic traits, and the relationship between leaf chemical- and structural traits and photosynthetic traits. Method: In the community, the dominant main woody species include Larix principis-rupprechtii, three broad-leaved trees, Fraxinus chinensis, Phellodendron amurense and Acer pictumsubsp.mono, and two shrubs, Lespedeza bicolorand Spiraea salicifolia. The 13 leaf traits were measured for the woody species in the L. principis-rupprechtii community in Bahushan, Beijing using portable analyzer during July-August in 2021. Photosynthetic traits included maximum net photosynthetic rate (P_nmax), saturation irradiance (I_sat), dark respiration rate (R_d), saturation intercellular CO₂ concentration (Ci_sat), maximum rate of carboxylation (V_cmax), maximum potential rate of electron transport (J_max), water use efficiency (WUE), and photosynthetic nitrogen-use efficiency (PNUE). The structural traits were leaf thickness (LT), specific leaf area (SLA), and leaf tissue density (LTD). The chemical traits were carbon-nitrogen ratio (C∶N), and nitrogen-phosphorus ratio (N∶P). One-way analysis of variance, Spearman correlation analysis, principal component analysis and linear regression were used to analyze the correlation of leaf traits and the effects of leaf chemical and structural traits on photosynthetic traits in the L. principis-rupprechtii community. Result: 1) The PNUE and SLA showed the largest inter-species variation with variation coefficient of 60.88% and 56.83%, respectively, indicating that the species in the commnuity competed for light resource. 2) Shrubs had higher SLA in order to increase light acquisition ability on vertical structure in the community. Meanwhile, N∶P in tree leaves was 14.58, while that in shrub leaves was 21.10. Compared with trees, shrubs had lower C∶N, but higher N∶P, indicating that the shrub allocated more nitrogen into leaf to obtain light and maintain growth. 3) C∶N, N∶P and SLA were 18.19, 16.04 and 193.77 cm²·g^?1 in broad-leaved trees, respectively, and were 39.6, 10.2 and 82.2 cm²·g^?1 in needle-leaved trees, respectively. Compared with broad-leaved trees, the needle-leaved trees had higher C∶N, but lower N∶P and SLA, indicating that the needle-leaved trees tended to construct the more defensive organization and had higher resistance to stress and lower light interception capability. 4) L. principis-rupprechtii was located at “slow investment-return”, shrubs were at “fast investment-return” in leaf economic spectrum. L. principis-rupprechtii had higher WUE but lower PNUE, suggesting that the trade-off between WUE and PNUE occurred, with WUE increasing at the expense of PNUE. 5) Compared with other broad-leaved trees and shrubs, the P_nmax of A. pictum subsp. mono and S. salicifolia were not obviously higher, but the R_d were significantly lower than other species. 6) The I_sat, R_d WUE and PNUE were significantly correlated with C∶N, LT and SLA (P<0.05). Conclusion: These results suggest that there is obvious leaf economics spectrum existed across the woody species in the community, and the interspecific competition is mainly for light resource. Although A. pictum subsp. mono and S. salicifolia are not the dominant species in the community, their net carbon sequestration capacity in per unit area is stronger than other species. The C∶N, LT and SLA can be used as the indicators predicting the photosynthetic capacity. Species with higher C∶N, LT and lower SLA have higher tolerance to strong light and higher water use efficiency, but have stronger utilization of weak light and less carbon consumption. Meanwhile, photosynthetic nitrogen utilization efficiency is lower. The results can provide theoretical support for subsequent forest management.

Objective: This study was carried out to explore the responses of the sap flow and transpiration to the environmental factors at different time scales, and the result here could provide scientific support for formulating appropriate management for forest ecosystem and improve the accuracy of assessment of water conservation function of forest ecosystem. Method: The thermal diffusion method was used to continuously monitor the sap flow of Ulmus macrocarpa in Songshan, Beijing during the growing season in 2019 and 2020, and the relevant environmental variables were observed simultaneously. Linear and non-linear regressions were used to analyze abiotic control on sap flow. Result: The cumulative transpiration was 333.85 mm and 252.27 mm in 2019 and 2020, respectively, with daily means of 1.82 mm and 1.37 mm in the two years, respectively. Seasonally, the J_s was controlled by shortwave radiation (R_s), air temperature (T_a), water vapor pressure deficit (VPD). The relationships between J_s and R_s, T_a and VPD were significantly and positively linear, with the coefficient of determination R² being 0.93, 0.88 and 0.89, respectively, and with a VPD threshold of 0.9 kPa in growing season. The relationship of J_s and R_s was stronger (higher R²) than that with both T_a and VPD in the same month. The daily variation in J_s lagged that of R_s, but preceded that of T_a and VPD. The relationships between g_s and R_s, T_a, and VPD were non-linear correlation, being different from the responses of J_s to environmental factors. Conclusion: There are differences between seasonal and diurnal scale in environmental control mechanism of sap flow, the changes of environmental factors affect the sap flow of plant mainly through inducing stomatal changes. The time lag between J_s and environmental factors is explained by the difference in response of canopy stomatal conductance (g_s) and J_s to environmental factors. The time lag and sensitivity of sap flow to environmental factors can reflect drought tolerance and environmental adaptability. These results would help estimation of transpiration under similar environmental conditions and improvment of hydrological model for assessment of water conservation function of forest ecosystem.

Objective: This study aims to quantify carbon fluxes in plantation ecosystem and examine the role of environmental factors in regulating carbon fluxes, so as to improve the accuracy in assessing carbon sequestration function in plantation ecosystem. Method: The eddy-covariance (EC) technique was used to continuously monitor ecosystem carbon fluxes in a typical Pinus tabuliformis plantation ecosystem in Miyun, Beijing in 2021. Air temperature (T_a), vapor pressure deficit (VPD), photosynthetically active radiation (PAR), and soil water content (SWC) were continuously monitored in situ. The seasonal variation characteristics of ecosystem carbon fluxes and their responses to environmental factors were examined. Result: The cumulative annual gross ecosystem production (GEP), annual ecosystem respiration (RE), and net ecosystem production (NEP) in 2021 were 315, 291, and 24 g·m^?2, respectively. GEP and RE were higher in the growing season (from April to October) and however, they were close to 0 g·m^?2 in the non-growing season. The maximum daily GEP, RE, and NEP were 4.7, 3.3, and 3.1 g·m^?2, respectively. The monthly maximum carbon assimilation rate was unimodal during the growing season, with its maximum in July. NEP had positive relationships with GEP (P<0.01) during the growing season and the peak growing season, and the coefficients of determination were 0.68 and 0.80, respectively. The relationships between NEP and PAR in differentT_a, VPD, and SWC conditions were not significantly different. The responses of NEP and GEP to T_a, VPD, and SWC were all unimodal, peaking at about 25 ℃, 10 hPa, 0.2 m³·m^–3, respectively. Low soil moisture had no significant effect on the responses of NEP and GEP to T_a and VPD, while it reduced the temperature sensitivity of RE. Conclusion: This study has found that P. tabuliformis plantation ecosystem in the study area is carbon sink during the growing season, the peak growing season, and the whole year. The change in NEP is mainly dominated by change in GEP. High T_a, VPD, and SWC all reduce NEP by limiting GEP. Low soil water condition has little indirect effect on the responses of NEP and GEP to T_a and VPD, while it limites the temperature sensitivity of RE. These results are important for further understanding of the regulations of environmental factors on the carbon cycling of P. tabuliformis plantation ecosystem under climate change.

Objective: This study is aimed to investigate the variation characteristics of soil carbon and nitrogen storage of typical communities in the process of vegetation natural restoration succession, and provide data support for vegetation restoration and reconstruction in southwest karst area. Method: By using the space-for-time substitution method, the natural restoration succession stages of abandoned cropland (abandoned cropland for half a year), grassland (5-10 a), shrub (15-25 a), shrub-forest (30-40 a) and forest (50-60 a) in karst trough valley of Zhongliang Mountain in Chongqing were selected as the research objects, permanent plots were established in each succession stages; the contents of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^?-N), soil carbon-nitrogen ratio (C/N) and soil pH in 0-10, 10-30, 30-50, 50-70 cm were measured to estimate the soil carbon and nitrogen storage in each succession stage, and analyze the soil carbon and nitrogen content and storage characteristics in different stages of natural restoration succession. Result: The natural vegetation restoration and succession significantly increased SOC and TN contents and storage (P < 0.001), and the highest SOC and TN contents and storage were found in shrub-forest, with contents of 57.75 g·kg ^?1 and 6.31 g·kg^?1 and storage of 87.71 t·hm^?2 and 10.06 t·hm^?2, respectively, which increased by 51.88% and 30.31% compared with the abandoned farmland stage. The SOC storage in 0-30 cm soil layer accounted for 64.02%-73.68% of the 0-70 cm soil layer, and the soil TN storage accounted for 64.73%-78.55%. The soil C/N in 0-70 cm soil layer increased first and then decreased during the natural vegetation restoration succession, and the soil C/N in shrubland stage was the highest, which was 9.56. The C/N ratio of forest stage in 0-30 cm soil layer was the highest, which was 9.98, and the C/N ratio of 30-70 cm soil layer was relatively low. Soil NH₄⁺-N storage of shrub-forest stage was the highest (0.103 t·hm^?2), soil NO₃^?-N storage of abandoned farmland stage was the highest (0.076 t·hm^?2), followed by shrub-forest stage (0.038 t·hm^?2). The SOC and TN storage were significantly positively correlated with soil NH₄⁺-N, NO₃^?-N and TP contents (P < 0.05), in addition, the SOC storage was also significantly positively correlated with soil TN and TK contents ( P < 0.05), and the soil TN storage was also significantly positively correlated with SOC contents ( P < 0.05). Soil C/N was positively correlated with SOC, TN, and NH ₄⁺-N contents (P < 0.01), positively correlated with TP contents ( P < 0.05), and negatively correlated with TK contents ( P < 0.01). Conclusion: The succession of natural vegetation restoration in the karst area can significantly improve soil carbon and nitrogen content and storage (P < 0.001), and the effects on carbon and nitrogen content and storage and C/N in the 0-30 cm soil layer were more obvious than those in the 30-70 cm soil layer. There is a certain correlation between carbon and nitrogen storage and nutrient cycling. From the natural restoration succession of vegetation to the shrub-forest stage, soil carbon and nitrogen storage have been significantly increased to the peak ( P < 0.001); and the natural restoration of vegetation has a significant influence on the improvement of soil quality ( P < 0.001).

Objective: In this study, a field experiment was set up to explore the response of soil respiration rates (R) and its components to nitrogen (N), phosphorus (P) addition and their interaction, and this study aimed to reveal the role of biotic and abiotic factors in regulating R and provide a scientific basis for the carbon cycling and model prediction of nutrient addition in Phyllostachys edulis forest ecosystem. Method: Nitrogen and phosphorus were added every two months by spraying them under the canopy in a phosphorus deficient bamboo forest from June 2017. Four treatments were conducted, including control（CK）, nitrogen addition（N）, phosphorus addition（P） and nitrogen and phosphorus addition together（N + P）. Soil total respiration rates and soil heterotrophic respiration rates were measured with Li-8100 from September 2017 to August 2018. At the same time, the soil temperature （T）, soil moisture （SM）, fine root and soil properties, fine root biomass and soil microbial properties were measured. Result: Both nitrogen and phosphorus addition did not significantly change fine root biomass of Ph. edulis, and thus had no significant impact on soil autotrophic respiration rate. However, nitrogen and phosphorus addition significantly decreased soil heterotrophic respiration rate , which were attributed to the increment of soil availability nitrogen content by nitrogen addition and decline of ratio of fungi biomass to bacteria biomass by phosphorus, respectively. The nitrogen and phosphorus addition had significant interactive effect on soil autotrophic and heterotrophic respiration rates. The phosphorus addition significantly increased the soil total respiration rate, while N addition as well as interactive effect of N addition and P addition did not significantly affect the soil total respiration rate. The model （R = ae^bT × SM^c） was able to explain the synergistic variation of T and SM in regulating R. P treatment reduced the determined coefficient of T and SM in regulating R. N, P and N + P treatments significantly reduced temperature sensitivity of soil total respiration（CK = 2.64, N = 2.54, P = 2.10, N + P = 2.39）and soil heterotrophic respiration（CK = 2.32, N = 2.03, P = 1.94, N + P = 1.75）, but increased temperature sensitivity of soil autotrophic respiration （CK = 2.80, N = 2.95, P = 2.44, N + P = 4.35）. Conclusion: The soil autotrophic respiration and heterotrophic respiration of phosphorus deficient Ph. edulis forest have asymmetrical responses to N and P addition and their interaction, and the different responses to nutrient addition should be fully considered when predicting soil carbon emission of P deficient Ph. edulis forest in the future.

Objective: Minjiang fir (Abies fargesii var. faxoniana) is an endemic and dominant tree species in the eastern Tibetan Plateau (TP). This paper aims to study the spatial correlation of the divergence phenomenon of Minjiang fir with slope aspect and elevation and to explore its driving force, so as to provide a scientific basis for climate reconstruction and predict distributions of natural forests in southwestern China. Method: In the Miyaluo Forest Region on the eastern margin of TP, a total of 875 tree cores of Minjiang fir were collected from four main distribution slope aspects (NE, N, NW, and W) and three elevation gradients (3 650, 3 800, and 3 950 m). After the growth trend of the tree ring was removed using dendrochronology, twelve tree ring standard chronologies of Minjiang fir were established based on terrain points. The regression analysis was used to study the divergence between the tree-ring index of Minjiang fir and the warming trend. The Pearson correlation analysis and sliding correlation analysis were used to reveal the relationships between the tree-ring index of Minjiang fir and climate factors from 1955 to 2019. Result: 1) There was no divergence in the radial growth of Minjiang fir in treelines of the four slope aspects, and the Minjiang fir trees on the west slope did not take place divergence. The tree-ring index of Minjiang fir on the N and NW slope aspects at the low and middle elevations and the NE slope at the low elevation showed divergence patterns with the warming trend. 2) Among the five diverged plots, the radial growth of Minjiang fir on the north slope at middle and low elevations as well as the northwest slope at low elevation showed a negative correlation with the precipitation during the growing season (June) (P<0.05). Minjiang fir on the N and NW slope at the middle elevation were negatively correlated with the precipitation in September and the temperature in October of the previous year, respectively (P<0.05). Tree ring indices of Minjiang fir on the N slope at the low elevation showed a negative correlation with the temperature in April and September (P<0.05). 3) From 1955 to 2019, the negative correlation between the tree-ring index of Minjiang fir on the middle elevation N slope and precipitation in September and June of the previous year tended to be significant (P<0.05). The negative correlation between the tree-ring index of Minjiang fir on low elevation N slope and the temperature in April and September tended to be significant, and the negative correlation with precipitation in June tended to be significant (P<0.05). A stable significant positive correlation was maintained between the tree-ring index of Minjiang fir on middle elevation NW slope and the mean temperature in October of the previous year (P<0.05). On the low-elevation NW slope, the negative correlation between the tree-ring index and precipitation in June tended to be significant (P<0.05), and the relationship with the mean temperature in June tended to be uncorrelated. The negative correlation between the tree-ring index of Minjiang fir on low altitude NE slope and the mean temperature in September, October, and December of the previous year, and in January, May, and September tended to be significant (P<0.05). Conclusion: The divergence phenomenon of Minjiang fir occurs at lower elevations on the south-facing slopes (NE and W) rather than on the north-facing slopes (N and NW). The drought stress on Minjiang fir occurs in the previous year's late growing season and the current year's non-growing season. Under the background of future warming, the growth response of Minjiang fir at the lower elevations is uncertain, but the radial growth of Minjiang fir trees in the treelines will be beneficial from warming.

Objective: Rapid and accurate detecting chlorophyll content in plant leaves is an important step to explore the photosynthesis, nitrogen nutrition, stress status and yield prediction. In this study, multispectral image spectral information was used to quickly and accurately detect plant chlorophyll content, in order to provide reference and technical guidance for plant growth monitoring, stress diagnosis, and precise management. Method: In this study, the 1-year-old seedlings of Ilex dabieshanensis and Ilex verticillata were targeted. A multispectral camera, RedEdge-MX, was used to construct a system for extracting plant phenotypic information. The system collected multispectral images of the leaves of the two species at maturity and growth stages in five bands, including blue (B), green (G), red (R), near infrared (NIR), and red edge (RedEdge). The multispectral images were processed to obtain the spectral reflectance at each band of each leaf. Correlation analysis was conducted between the obtained spectral reflectance and the relative chlorophyll content (SPAD value) obtained by using a hand-held chlorophyll content analyzer. The traditional support vector regression (SVR) algorithm and the grid search (GS) algorithm, genetic algorithm (GA) and particle swarm optimization (PSO) were used for inversion modeling, respectively. The inversion models were compared, and a model with the highest fitting degree was obtained and it was able to quickly and accurately predict plant chlorophyll content using multispectral image spectral information. Result: The results showed that the correlation between the spectral reflectance and SPAD was obtained with the inversion model selected by comparing the traditional SVR algorithm with the optimized GS-SVR algorithm, GA-SVR algorithm and the PSO-SVR algorithm, the model fitting degrees were $ {R}_{1}^{2} $ =0.24 and (root mean-square error) $ {\mathrm{R}\mathrm{M}\mathrm{S}\mathrm{E}}_{1} $ =0.160; $ {R}_{2}^{2} $ =0.72, $ {\mathrm{R}\mathrm{M}\mathrm{S}\mathrm{E}}_{2} $ =0.097; $ {R}_{3}^{2} $ =0.84, $ {\mathrm{R}\mathrm{M}\mathrm{S}\mathrm{E}}_{3} $ =0.073; $ {R}_{4}^{2} $ =0.91, $ {\mathrm{R}\mathrm{M}\mathrm{S}\mathrm{E}}_{4} $ =0.066, respectively. Secondly, (adjusted R-squared) ${R}_{\mathrm{adjusted1}}^{2}$ =0.23, (mean absolute error) $ {\mathrm{M}\mathrm{A}\mathrm{E}}_{1} $ =0.119; ${R}_{\mathrm{adjusted2}}^{2}$ =0.71, $ {\mathrm{M}\mathrm{A}\mathrm{E}}_{2} $ =0.069; ${R}_{\mathrm{adjusted3}}^{2}$ =0.83, $ {\mathrm{M}\mathrm{A}\mathrm{E}}_{3} $ =0.050; ${R}_{\mathrm{adjusted4}}^{2}$ =0.87, $ {\mathrm{M}\mathrm{A}\mathrm{E}}_{4} $ =0.044. Conclusion: After comprehensive comparison, it is found that the optimized PSO-SVR algorithm has the best inversion prediction effect. In this study, by collecting multispectral images of plants, the optimized PSO-SVR algorithm is used to obtain the optimal inversion model of spectral reflectance and SPAD in five bands, which can realize the rapid detection of chlorophyll content in plant leaves. Combined with the multispectral imaging and machine learning algorithms, the accuracy and robustness of the models have been improved. Meanwhile, the results of this study can be extended to remote sensing level to realize the inversion of vegetation chlorophyll in a large area, providing theoretical basis and technical support for accurate forest seedling growth monitoring, stress diagnosis and dynamic regulation.

Objective: The purpose of this study is to establish the corresponding relationship between morphological indicators of flower development and the meiotic process of Hydrangea, and to observe the chromosome behaviors in microspore mother cells and the pollen characteristics, so as to lay the foundation for the germplasm innovation of Hydrangea. Method: The inflorescences at different developmental stages were collected and pressed onto a glass slide and stained with carbol fuchsin, and the meiotic process of pollen mother cells (PMCs) of fertile flowers was observed. The proportion of abnormal meiotic phenomena was counted, and the pollen was cultured a liquid pollen germination medium and the pollen germination rate was measured. Result: 1) Before the opening of decorative flowers around the inflorescence of Hydrangea macrophylla ‘Endless Summer’, the PMCs of fertile flowers displayed condensed cytoplasm and prominent nucleoli. When the decorative flowers at the edge of the inflorescence opened slightly, the fertile flower buds were 3–3.5 mm in diameter, and their anthers were about 0.5 mm in width and 1 mm in length. At this point, the PMCs meiosis entered the pachytene stage. With further development of fertile flowers, various stages from diakinesis to pollen grains were able to be observed. When the decorative flowers at the edge of the inflorescence were fully open the meiosis process terminated. At this time, the buds of fertile flowers were about 4 mm in diameter, and the anthers were about 1 mm in width and 1.5 mm in length. 2) The chromosome of H. macrophylla ‘Endless Summer’ PMCs behaved normally during meiotic process. The meiotic process of the microspore mother cells of the two hybrids F₁ showed a lot of abnormal phenomena. In the hybrid of H. macrophylla ‘Magical Jade’ × H. chinensis, 46.41% of the microspore mother cells showed chromosomes detached from the equatorial plate at meiosis metaphase I stage, 52.48% of the cells had laggard chromosomes or formed chromosome-bridge at anaphase I and telophase I stage. Micronucleus appeared in 35.11% of the cells at the telophase II stage. In the H. macrophylla ‘Taube’ × H. macrophylla ‘Veitchii’ hybrid, the rate of unpaired chromosomes in metaphase I was 15.31%, and around 17.30% of cells showed laggard chromosomes or chromosome-bridge at anaphase I and telophase I stage. No micronucleus was observed in the telophase II period. 3) The pollen grains of H. macrophylla ‘Endless summer’ were spherical and uniform in size, with a diameter (16.72±0.75) μm and pollen germination rate was about (25.15±3.54)%. The diameter of the pollen grains of H. macrophylla ‘Taube’× H. macrophylla ‘Veitchii’ hybrid F₁ was (16.60±1.73) μm, and the pollen germination rate was about (16.26±1.72)%. The spherical pollen grains of H. macrophylla ‘Magical Jade’ × H. chinensis hybrid were able to be divided into two categories: the diameter of small pollen grains was (16.48±0.71) μm, and that of large pollen grains was (23.30±1.82) μm, which was about 1.41 times larger than the small pollen grains. The large pollen is speculated to be 2n pollen, which accounted for (6.12±1.01)% of the total pollen grains. Conclusion: The decorative flowers on the edge of the inflorescence are slightly open, and the diameter of the fertile flowers buds is 3–4 mm, which can be used as a marker of the initiation of meiosis of pollen mother cell in the Sect. Petalanthae of Hydrangea. H. macrophylla ‘Endless Summer’ and the hybrid of H. macrophylla ‘Taube’ × H. macrophylla ‘Veitchii’ have high pollen germination rate and can be further used as hybrid parents in later breeding work.

Objective: This study was aimed to understand the age-related tree basal area growth pattern of Korean pine (Pinus koraiensis), and explore the main factors affecting the radial growth in different growth stages, in order to provide a scientific basis for understanding the importance of tree age, environmental factors and functional traits in forest development and management. Method: 65 sample trees of P. koraiensis were selected from Liangshui National Nature Reserve in Heilongjiang Province, and the radial growth of tree stems was studied using the basal area growth rate (BAGR). We determined the environmental factors (light intensity, soil nitrogen content, soil water content, soil pH) and functional traits of leaves, branches, and roots. Then we analyzed the radial growth variation and explored how tree age, environmental factors, and functional traits affect the radial growth at different growth stages. Result: 1) The BAGR of P. koraiensis first increased and then decreased with rising tree age: when the age was less than 220 years, the BAGR increased with rising tree age. When it was more than 220 years old, the BAGR decreased with rising tree age. 2) For young trees (16-100 a), tree age, light intensity and soil pH had a positive effect on BAGR, the specific leaf area of needles had a negative effect on BAGR. 3) For middle-age trees (100-220 a), soil nitrogen content and wood density (WD) significantly and negatively affected the BAGR. 4) For old trees (220-285 a), tree age significantly inhibited the BAGR, the nitrogen content of roots, the nitrogen and phosphorus content per unit mass of needles promoted the BAGR, and the effect of root nitrogen content was more significant. Conclusion: Tree age, environmental factors and functional traits jointly drive the basal area growth of P. koraiensis trees, and the relative effects change with tree age. The factors limiting tree growth change from light to soil nutrient contents and physiological factors of trees with rising age.

Objective: The tree leaf biomass models of Chinese fir plantations were developed based on multiple variables, and the best model was selected to provide reference for accurate prediction of leaf biomass of Chinese fir. Method: Besides the three variables of sapwood area at breast height, diameter at breast height and diameter at crown base using 63 trees from 21 plots of different forest ages, the other variables related to leaf biomass were also considered. The nonlinear mixed model was considering the random effect of plot. In addition, exponential function, power function, and constant plus power function were used to eliminate the heteroscedasticity among the data. The best model was selected according to the model evaluation index AIC (Akaike information criterion), BIC(Bayesian information criterion), and Log Likelihood. The mixed model with different parameters was tested by likelihood ratio test. Finally, the leave-one-out cross-validation method was used to calculate coefficient of determination (R²), total relative error (TRE), and mean absolute error (MAE) to test the models. Result: The mixed models considered power function as heteroscedasticity structure performed the best among the three types of models. In addition, all the mixed models were better than the basic models, and the leaf biomass model developed based on diameter at crown base performed the best. Conclusion: The nonlinear mixed effect model (Model 16) based on diameter at crown base with R² values of 0.805 1 was used as the final model for individual leaf biomass of Chinese fir plantations, which was consistent with the pipe model theory. All the variables had certain biological and statistical significance and were easy to obtain in the field work (non-destructive). In addition, this study can also provide a reference for other tree species in predicting individual leaf biomass.

Objective: Understanding of the habitat quality of Hainan gibbons (Nomascus hainanus) is crucial to its population conservation. Therefore, this study aims to compare the differences in stand structure, plant species composition and diversity between the current habitat of Hainan gibbons in the natural forest and the potential habitat in the pine forest at the same altitude, and to explore the differences in habitat quality between the two types of habitats, which could help to scientifically evaluate the restoration status of pine forest and finally lay a theoretical foundation for the ecological space expansion of Hainan gibbons. Method: The existing natural forest habitat of gibbons and the potential habitat of pine forest in the Bawangling area of Hainan tropical rainforest national park at an altitude of 400-800 m were targeted. Based on the CTFS (center for tropical forest science) plot construction standard, a total of 59 plots with each area of 400 m² were set in the two habitats. The diversity characteristics and differences of stand structure, forest plants and gibbons’ edible plants in the two types of habitats were investigated and analyzed. Result: A total of 450 plant species in 93 families and 259 genera were found in the current natural forest habitats, including 86 edible plant species of 43 families and 70 genera which were mainly composed of Rubiaceae taxa. Whereas a total of 301 plant species in 74 families, and 186 genera were found in the pine forest, including 60 species of edible plants in 29 families, and 46 genera, with Camellia species being dominant. The stand structure factors of forest community plants in the natural forest habitats, such as the mean DBH (6.30 cm±5.90 cm), the mean tree height (6.02±4.92 m), mean crown area (5.21±12.52 m2), mean crown thickness (2.10±1.65 m), and plant density (6 136±1 930 plants·hm^?2), were all greater than those in the pine forest potential habitats (mean DBH 5.19±4.19 cm, mean tree height 5.04±3.38 m, mean crown area 2.87±7.75 m2, mean canopy thickness 1.99±1.62 m, and plant density 5 517±1 901 plants·hm^?2). With the increase in diameter class and tree height, the tree density in the pine forest reduced more significantly than that in the natural forest. At the overall scale, the Shannon-Wiener index and richness index of forest community plant species in the natural forest habitat were the highest (H'=4.37, S=452). The Shannon-Wiener index and richness index of large edible plant species in the pine forest potential habitat was the lowest ( H'=4.37, S=452), while the evenness index was the highest (E=0.83). At the scale of 20 m×20 m plot, the plant species richness index of natural forest habitat was significantly higher than that of the pine forest potential habitat (Forest community plants: t=4.72, P=0.02; Edible plants: t=4.61, P=0.01; Small edible plants: t=2.03, P=0.02), while the Shannon-Wiener index and richness index of large edible plants of the pine forest potential habitats were extremely significantly lower than those of the natural forest habitats (Shannon-Wiener index: t=5.03, P<0.001; richness index:t=4.58, P<0.001). The similarity of the community plants between the two habitats was the highest at the family level (C_J=0.76). At the species level, the similarity of small edible plants was the highest ( C_J=0.67), while that of large edible plants was the lowest ( C_J=0.31). The order of the difference in plant beta diversity between the two habitats was large edible plants ( F=1.64, P<01) > forest community plants (F=48.10, P<0.001) > edible plants (F=7.72, P=0.01) > small edible plants ( F=7.72, P=0.01). Conclusion: Compared with the natural forest habitat, the pine forest potential habitat does not only lack large broad-leaved trees and also large edible plants which are suitable for Hainan gibbons to inhabit, but the plant species diversity is also significantly lower than the natural forest habitats. Thus, the survival needs of Hainan gibbons could not be met in the pine forest habitats for the time being. Nevertheless, the species composition and diversity of small edible plants in the pine forest potential habitats are similar to that of the natural forest habitats, which shows that there is potential for the pine forest potential habitats to be developed into Hainan gibbons’ habitat. While large edible plants are the key ecological species for the current restoration of the pine forest's potential habitats.

Objective: Female adults of Sclerodermus pupariae can develop into winged or wingless morphs. However, winged females are only occasionally found in both wild and mass-reared populations. This study aims to investigate whether there are differences in the parasitic behavior and progeny development between winged and wingless female individuals, so as to provide a theoretical basis for further clarifying the necessity of inducing production of winged females in the parasitoid mass-rearing. Method: The parasitism ability, pre-oviposition period, offspring immature duration, fecundity, and male offspring proportion of winged and wingless females were measured in the laboratory conditions. Result: 1) Both winged and wingless females could complete four times of parasitism. There was no significant difference in parasitism ability between the two types of morphs of the parasitoids, but the parasitism ability decreased with the increasing parasitism times. There was no significant difference in longevities of winged and wingless females, with an average lifespan of approximately 43 days. 2) There were no significant differences in the pre-oviposition period and the offspring immature duration between winged and wingless females. 3) The total numbers of offspring and male proportions of winged and wingless females exhibited no significant differences. Winged and wingless females could produce approximately 103 and 98 progenies, respectively. Their male progeny proportions were 10.59% and 6.90%, respectively. Both winged and wingless females had the four parasitism times, and their offsprings in the first two broods were dominated by females, and the second two broods of offsprings were dominated by males. Conclusion: The parasitism and fecundity of winged females are not lost due to the development of wings, and the reproductive fitness of winged females does not decrease in comparison to the wingless individuals. Due to the strong self diffusion ability of winged females after release, more winged females produced by artificial regulations would achieve benefits for biocontrol application of this parasitoid.

Objective: In order to protect the surface and improve the visual effect of wood, this paper presents a preparation method and properties of the green, environmentally-friendly and fast-drying wax oil for wood, which provides theoretical basis and technical supports for the development and industrialization of wood wax oil. Method: Taking natural and renewable vegetable oil and wax as the main film-forming materials, ascorbic acid 6-palmitate (L-AsA₆P) and iron[III] 2-ethylhexanoate (Fe-eh) were used as the synergistic drying agent to prepare an environmentally-friendly and fast-drying wood wax oil. Then the commercial wood wax oil as the control group, Entandrophragma cylindricum was used as the coating substrate, and the properties of the film were also evaluated. Result: The experimental results showed that the ratio of L-AsA₆P to Fe-eh had significant effects on the drying time, glossiness and contact angle of wood wax oil. It had the fastest dry speed when the molar ratio of L-AsA₆P to Fe³⁺ in Fe-eh was 5∶1, its surface dry time was 1.2 h and the actual dry time was 3.5 h; compared with the dry time of reference samples, it was decreased by 25% and 34.3%, respectively. Its glossiness was increased by 1.1 times, and the contact angle was always kept above 95°, so the purposes that improving the visual effect and hydrophobicity of wood was achieved. In addition, the hardness, adhesion, water resistance of the film were similar to those of control group, and the total color difference（ΔE) was lower. The analysis of digital images collected by scanning electron microscope (SEM) showed that the prepared wood wax oil not only filled the bare cell cavities on the surface of the substrate, but also penetrated into the inside of the wood through the pits. It was confirmed by FTIR spectroscopies that the esterification reaction took place between carboxyl groups in the fatty acid chains of wood wax oil and hydroxyl groups in the substrate, which formed strong chemical bonds, and presented excellent adhesion performance. Conclusion: L-AsA₆P and Fe-eh as the synergistic drying agents had positive effects on increasing the drying speed of the wood wax oil. When the molar ratio of L-AsA₆P to Fe³⁺ was 5∶1, the prepared wood wax oil had the best drying performance, strong adhesion and protection abilities to the substrate. Furthermore, it could improve the surface decoration effect of the substrate effectively.

Shrinkage and swelling of wood are critical characteristics that impact its processing and utilization. This is closely link to the dimensions and stability of wood products. The complexities of shrinkage and swelling are closely correlated with the multi-scale hierarchical structure of wood, varying from macro- to micro-scales. The shrinkage and swelling behavior of wood is investigated across macro-, meso-, and micro-scales to establish an organic relationship between them. This contributes significantly to a better understanding of the occurrence and evolution mechanism and has important theoretical and practical implications for in-depth comprehension of wood properties and its rational utilization. In this paper, the wood shrinkage/swelling behavior and its hysteresis phenomena under macroscopic scale (clear wood sample), mesoscopic scale (growth ring) and microscopic scale (wood cells) were reviewed. This paper summarized the occurrence and evolution of the shrinkage and swelling behavior of wood at three scales, as well as the test methods and technical means employed to measure these phenomena in wood with multi-scale structures. Meanwhile, some suggestions for future research about the shrinkage and swelling behavior of wood with multi-scale structures are proposed: 1) To conduct a systematic investigation into the shrinkage and swelling behavior of softwood and hardwood at the meso- and micro-scales, utilizing growth rings and wood cells, in order to establish the structure-activity relationship between multi-scale structures and their shrinkage and swelling performance. 2) To reveal the differential responsive law and interaction mechanisms of the shrinkage/swelling behavior of wood induced by anisotropy, heterogeneity, and the diversity of cell types. 3) To illuminate the time hysteresis and strain hysteresis phenomena of the shrinkage and swelling behavior. 4) To introduce the related theoretical models, such as the application of finite element method, with the aims to build a visual element finite of the free shrinkage and swelling of wood with multi-scale structures.