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Differences in the Water-retention Function of Humus Layer between Two Typical Forests with Different Densities in the Qinling Mountains
WANG Ya-ping, ZHANG Shu-lan, HAN Yong, DONG Xin-yu, ZHAO Yu-wei, WAN Ge
, Available online  , doi: 10.12403/j.1001-1498.20220377
Objective The differences in water-retention function of humus layer in typical forests with different densities in the Qinling Mountains were explored to provide basis for the vegetation construction. Methods Three plots with different densities (low, medium, and high) of Pinus tabulaeformis forest and Quercus aliena va.acuteseata forest were selected in Huoditang of Qinling Mountains. The indoor soaking and entropy weight methods were used to quantitatively analyze and comprehensively evaluate the water-retention function of humus layer. Results ①The thickness of humus in Pinus tabulaeformis and Quercus aliena va.acuteseata was 3.48~5.14 cm and 6.54~9.48 cm, respectively. The weight was the largest when the density was mediumwith 9.09 and 5.61 t·hm−2, respectively. The humus of Pinus tabulaeformis forest was mainly semi-decomposed layer (56.5%~60.55%), while that of Quercus aliena va.acuteseata forest was mainly undecomposed layer (63.58%~74.53%); ②The maximum water holding capacity of humus in Pinus tabulaeformis forest was found in medium density (24.55 t·hm−2), while that in Quercus aliena va.acuteseata forest increased with the increase of density, and reached 17.8 t·hm−2 in high density. The semi-decomposed layer of Pinus tabulaeformis forest and the undecomposed layer of Quercus acutissima forest played a major role in the absorption and retention of water by humus in the two forests; ③The accumulated water holding capacity of humus increased rapidly within 10 minutes after soaking, and the water holding growth rate of humus in Quercus aliena va.acuteseata forest was better than that of Pinus tabulaeformis forest. With the increase of soaking time, the water absorption rate of humus first decreased rapidly, then gradually decreased and tended to 0. The water holding rate(capacity), water absorption rate and soaking time of humus showed logarithmic and power function, respectively. Conclusion The water retention function of the semi-decomposed layer in Pinus tabulaeformis and undecomposed layer in Quercus aliena va.acuteseata forest can be complement each other, and the best performance of the Quercus aliena va.acuteseata forest can be reached when the density was 725 trees·hm−2. It is suggested to build a Pinus tabulaeformis Quercus aliena va.acuteseata mixed forest and control the density reasonably, so as to fully contribute to the hydrological function of humus.
Effects and Sensitivity of Progressive Drought on Photosynthetic Characteristics of Quercus liaotungensis Seedlings
WANG Li-min, ZHOU Shuai
, Available online  , doi: 10.12403/j.1001-1498.20220230
Objective To investigate the response of photosynthetic system of leaves in Quercus liaotungensis seedlings under progressive drought and select drought sensitive indicators. Method Based on the progressive drought stress method in pots, we performed variance analysis (ANOVA) and LOESS nonlinear fit on leaf droop angle, chlorophyll fluorescence, and photosynthesis of 2-year-old Q. liaotungensis seedlings. Result The results indicated that progressive drought had the most significant effect on photosynthetic gas exchange, followed by leaf droop angle and electron transfer and energy dissipation of PSII. According to the influence of soil relative water content (SRWC) to photosynthetic characteristics, the drought response of the photosynthetic system of Q. liaotungensis seedling could be classified into four stages: Stage I (no stress, 26%>SRWC>20%), photosynthetic gas exchange parameters did not drop; Stage II (moderate stress, 20%>SRWC>14%), the effect of stomatal restriction was evident and the leaf droop angle was lowered to -14.0 ± 1.7°; Stage III (high stress, 14%>SRWC>8%), the water use efficiency (WUE) of leaf and the gas exchange parameters decreased significantly, and the leaf droop angle was lowered to -43.2 ± 10.3°, which indicated that SRWC lowered to 14% was the irrigation water threshold values for Q. liaotungensis seedling; Stage IV (extreme stress, SRWC<8%), the electron transport and energy dissipation of PSII changed significantly, the photosynthetic apparatus were severely damaged, the leaf droop angle was lowered to -68.5 ± 6.7° indicated that SRWC lowered to 8% was the lethal threshold for leaf of Q. liaotungensis seedling. Based on the stage differences in the leaf droop angle responses to soil drought, it could be used as the warning index of the irrigation water threshold value of Q. liaotungensis seedlings. The number of reaction centers per unit area in PSII (RCO/CS), the absorption flux per reaction center in PSII (ABS/RC), the flux of energy dissipated in processes other than trapping per active in PSII (DIO/RC), and the leaf performance index (PIABS) could be used as warning indexes of the lethal threshold for leaf. Conclusion In this study, the stage differences of the photosynthetic system of Q. liaotungensis seedling‘s leaf response to soil drought were observed, therefore determining the irrigation water threshold values and sensitivity indicators reflecting soil drought, which provides a theoretical basis for developing an efficient irrigation strategy for Q. liaotungensis seedlings.
Plant Community Succession in the Burned Area of Picea asperata- Abies fargesii Forest on the Northeastern Edge of the Qinghai-Tibetan Plateau
ZHOU Xiao-lei, YANG Fu-qiang, TIAN Qing, ZHOU Xu-jiao, ZHAO An, HE Wan-peng, ZHAO Yan-li, JIANG Li-hong
, Available online  , doi: 10.12403/j.1001-1498.20220435
Objective To analyze the dynamic changes of species composition and plant biodiversity at different succession stages in the burned area of Picea asperata- Abies fargesii forest on the northeastern edge of the Qinghai-Tibetan Plateau for providing a scientific reference for scientific management of plant communities in burned areas.. Method Using the method of space-for-time substitution, plant communities in four different succession stages were selected on the northern slope of Mount Dieshan, including5-year post-fire succession (5 a), 15-year post-fire succession (15 a), 23-year post-fire succession (23 a) and the climax forest community (Climax). The species composition of plant communities, and species important value, α diversity index and β diversity index were calculated. Result 1) The species richness of the community and the number of plant decreased during the succession of plant community in the burned area. Among them, species richness and the number of plant (4 008 ± 298 individual ·400 m−2) in the community 5 a were the largest, but those in the Climax community were the least (1 759 ± 90 individual ·400 m−2). The Margalef index and the Shannon-Wiener index of the 5 a community in the herb layer, the Climax community in the shrub layer and the tree layer were the largest. 2)Based on the important value, the communities of 5 a, 15 a, 23 a and Climax in four different stages can be named as Rosa sweginzowii + Fargesia spathacea + Carex crebra, Lonicera tangutica + Salix heishuiensis + Carex crebra, Picea crassifolia-Betula albosinensis + Rosa sweginzowii + Carex crebra, Abies fargesii-Picea asperata + Lonicera tangutica + Carex crebra community, respectively. 3) The heterogeneity of herbaceous community at different succession stages were 5 a (0.07) < 15 a (0.12) < 23 a (0.19) < Climax (0.22). 4) The plant abundance in stages 5 a, 15 a and 23 a presented the geometric progression distribution, indicating that the environmental conditions were conducive to herb growth and species with deterministic niche occupied a dominant role in community construction. The plant abundance in Climax stage showed an “S” distribution which belongs to late successional community because the "intermediate-type" species occupied the vast majority of the community. 5) According to the β diversity index, the shrub layer of 4 succession stages could be divided into initial shrub (5 a) and stable shrub (15 a, 23 a and Climax), and the herb layer could be divided into drastically changing layer (5 a and 15 a) and stable layer (23 a and Climax). Conclusion With the succession of plant communities, the species richness decreases in the burned area of Picea asperata- Abies fargesii forest on the northeastern edge of the Qinghai-Tibetan Plateau, and the similarity between communities become closer. The succession of plant communities in the burned area is a positive succession, and the succession process is shrub- deciduous broad-leaved forest - coniferous forest - Picea asperata-Abies fargesii forest.
Variations on the Height Growth and Photosynthetic Characteristics of Pinus massoniana Lamb. Seedlings along a Soil Phosphorus Content Gradient
XU Jin, LEI Lei, ZENG Li-xiong, LIU Ya-hui, WAN Yi, NI Yan-yan, JIAN Zun-ji, DENG Xiu-xiu, ZHANG Jia-jia, XIAO Wen-fa
, Available online  , doi: 10.12403/j.1001-1498.20220250
Objective To study the response of Pinus massoniana seedlings of height growth and photosynthetic characteristics under different phosphorus concentrations, reveal the adaptation mechanism of P. massoniana to low phosphorus environment, and provide experimental basis for the management and accurate growth simulation prediction of P. massoniana forest. Method From May 2021, to November 2021, two-year-old seedlings of P. massoniana were planted in 7 different soil phosphorus concentrations, including control group (2.325 mg·kg−1, CK), no phosphorus group (0AP), with an eighth of CK (1/8AP), a quarter of CK (1/4AP), a half of CK (1/2AP), two times of CK (2AP), and four times of CK (4AP); and then the growth and photosynthetic parameters were tested. Result Relative height increment (RHI) and photosynthetic parameters of P. massoniana seedlings were affected by growing times and soil phosphorus concentrations. RHI during from May to June (RHI5-6) was higher than that from July to August (RHI7-8) and September to October (RHI9-10). RHI5-6 of 4AP was significantly higher than that of 1/8AP. Relative growth rate of seedlings was positively correlated with soil phosphorus concentrations (P<0.05), and linearly increased with phosphorus concentrations. Net photosynthetic rate (Pn), conductance to H2O (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr) were significantly affected by soil phosphorus content, growing time and their interaction. And all of them reached their peak in July to September. Pn, Gs and Ci were positively correlated with RHI. Growing time had a promoting effect on RHI, Pn, Ci and Gs. Conclusion The height growth and photosynthetic parameters of P. massoniana seedlings are significantly affected by soil phosphorus concentrations. P. massoniana seedlings have a special adaptive mechanism to the low-phosphorus environment by regulating photosynthesis and the dynamic changes of height growth.
Characteristics of Radial Growth of Picea schrenkiana at Different Ages and Their Simulation
HOU Tian-hao, JIANG Sheng-xia, WANG Yong-hui, ZHANG Tong-wen, YU Shu-long, WANG Zhao-peng, GUO Dong, RUXIANGULI·Abudoureheman, SONG Jing-hui
, Available online  , doi: 10.12403/j.1001-1498.20220616
Objective In this study, we developed two tree-ring chronologies using samples of Schrenk spruce (Picea schrenkiana) that were collected from the upper and lower treeline in the middle of the northern slope of Tianshan Mountains, and analyzed the radial growth characteristics of trees. Method According to the tree ages, the lower treeline spruce was divided into young, middle-aged and old groups. The ARIMA model was established to simulate the radial growth of spruce at different ages based on basal area increment. Results The analysis results showed that the tree-ring width chronology of the lower treeline contains more climate information comparing with the upper treeline. Among the BAI changes of three tree age groups simulated by the ARIMA model, the model fitting the middle aged trees performed the best (R² = 0.832). Considering the ARIMA model is modeled based on the univariate self-change trend, we analyzed the radial growth trend before and after the climate change, and found that the BAI of young spruce increased significantly overall, but the growth rate slowed down gradually. Conclusion The radial growth of middle-aged and old spruce showed a decreasing trend before the abrupt change of temperature. But after the abrupt change of temperature, the BAI of middle-aged spruce tends to be stable and the BAI of old spruce changes from a decreasing trend to an increasing trend.
Population Structure and Quantitative Dynamics of a Wild Plant with Extremely Small Populations Hopea hainanensis
LUO Wen, XU Han, LI Yan-peng, XIE Chun-ping, LU Chun-yang, LIANG Chun-sheng, SU Hong-hua, LI Zi-li
, Available online  , doi: 10.12403/j.1001-1498.20220510
Objective Hopea hainanensis is not only a Wild Plant with Extremely Small Populations but also a national grade first-level key protected plant and a representative species of tropical rainforest in Hainan, China. Here, the population structure, dynamic change characteristics, and future development trend of Hopea hainanensis were explored for providing a scientific basis for protection and management. Methods In this study, the population structure and dynamic characteristics of Hopea hainanensis distributed in Jianfengling, Hainan was analyzed using population statistics, including static life table, survival curve, and time series prediction model. Results (1) The population structure of wild Hopea hainanensis in Jianfengling showed an inverted J shape, and the number of seedlings (age class I) accounted for 95.24% of the total individuals. (2) The slop populations in the primary forest and secondary forest in the Jianfengling area tended to grow, but there was a limitation in the growth of young trees during the transition from seedlings to saplings, resulting in a very small number of adults. (3) The regeneration ability of Hopea hainanensis population in primeval forests was lower than that in secondary forests, but the recovery process in secondary forests was more susceptible to external disturbance. (4) The Hopea hainanensis population in primeval forests and secondary forests would recover steadily after 2-5 age classes if the existing Hopea hainanensis population and their habitats in Jianfengling were well protected. Conclusion There are still a certain number of wild saplings in Jianfengling, Hainan. It is urgent to strengthen the protection of the existing wild Hopea hainanensis populations and promote the transformation of the seedlings to saplings in the natural state.
Soil Silicon Form Characteristics of Natural Castanopsis fargesii Forest at Different Altitudes in Guoyan Mountain
HE Dong-mei, CHEN Yi-fei, SU Yi, WANG Yun-xiang, HUANG Guo-qing, LIAO Xiao-li, FANG Shu-zhen, HUANG Wei, JIN Shao-fei, ZHENG De-xiang
, Available online  , doi: 10.12403/j.1001-1498.20220460
: Objective To better understand the characteristics of soil silicon morphology variation and its correlation with soil physi-chemical properties in Castanopsis fargesii stands at differentaltitudes in Guoyan Mountain for further illuminatingthe response mechanism of soil silicon morphology content to environmental changes in subtropical areas. Methods In order to gather soil samples from various soil layers (0−20, 20−40, and 40−60 cm) at differentaltitudes in Guoyanshan Nature Reserve, standard plots were set up at 600, 700, 800, and 900 m, respectively. Different soil silicon forms were extracted and measured to examine the effects of environmental changes on soil silicon forms. Results (1) Available silicon(258.26 mg·kg−1), water-soluble silicon (155.69 mg·kg−1), active silicon(388.97 mg·kg−1) and amorphous silicon (1561.97 mg·kg−1) in the high-altitidesoil weresignificantly higher than those in thelow altitudesoils with the data of 93.16, 78.38, 231.84, and 832.24 mg·kg−1, respectively. The availablesilicon (227.53 mg·kg−1)in deep soil layer (40−60 cm) was significantly higher than that in 0−20 cm (120.79 mg·kg−1) and 20-40 cm (171.37 mg·kg−1) soil layers. (2) The content of available silicon in soil was significantly positively correlated with the content of active silicon and water-soluble silicon. Active silicon was the most important direct contributing form to the increase of availablesilicon, andwater-soluble silicon was an important transitional form in the soil silicon transformation process.(3) Soil organic matter and soil pH had the most significant effects on the content of each soil silicon form, which explained the variations of14.1% and 9.2%, respectively. Soil organic matter was positively correlated with amorphous silicon and water-soluble silicon, and negatively correlated with soil active silicon and effective silicon, while soil pH was positively correlated with availablesilicon and active silicon, and negatively correlated with amorphous silicon. Conclusion Variations on environment and soil physical and chemical properties caused by altitude can change the content of silicon in soil.This study offers a foundation for successful soil silicon use and soil silicon morphology control in natural Castanopsis fargesii forest, which is crucial scientific advice for the preservation of natural Castanopsis fargesii forest.
Variation of Negative Air Ions and Its Influencing Factors in Typical Plantations in Rocky Mountain Area of North China
ZHANG Jia-xing, JIANG Li-ya, GAO Jun, JIA Chang-rong, LI Jian-xia, SANG Yu -qiang, ZHANG Jin-song
, Available online  , doi: 10.12403/j.1001-1498.20220568
Objective To explore the variation characteristics of Negative air ion (NAI) of typical plantations and the relationship between NAI and environmental factors in growing period and non-growing period in rocky mountain area of north China, and reveal environmental factors affecting NAI in different seasons in this area. Method The variation characteristics of NAI of typical plantations in Henan Xiaolangdi Earth Critical Zone National Research Station were measured from May to December in 2021 using the air negative ions, PM 2.5, PM 10 and meteorological data. Besides, the main environmental factors and variable importance measures affecting NAI of typical plantations in the area were analyzed by random forest algorithm. Results The diurnal variation of NAI in Quercus variabilis showed single peak curve in growing period but not obvious in non-growing period. The NAI of Platycladus orientalis showed single peak cure during the experiment period. The NAI concentration of Quercus variabilis plantations (740.32 ion·cm−3) was higher than that of Platycladus orientalis (703.74 ion·cm−3) during the observation period. The daily NAI of Quercus variabilis (858.94 ion·cm−3) was higher than that of Platycladus orientalis (724.33 ion·cm−3) during the growing period. The daily NAI of Quercus variabilis (621.70 ion·cm−3) was lower than that of Platycladus orientalis (683.16 ion·cm−3) during the non-growing period. The meteorological factors such as Air temperature (Ta), Relative humidity (RH), Vapor pressure deficit (VPD) and photosynthetically active radiation (PAR) in the growing period were higher than those in the non-growing period, while the particulate matter (PM2.5 and PM10) in the non-growing period was higher than that in the growing period. The concentration of PM10 was higher than that of PM2.5 during the experiment period. There was no significant difference between Wind speed (WS) between the growing period and non-growing period. The random forest method revealed that the main environmental factors affecting the NAI concentrations of Quercus variabilis and Platycladus orientalis in the growing period were VPD, PAR and WS, and their variable importance measures were 20.22, 15.08 ,14.71, respectively, and 25.08, 16.76, 16.49, respectively. The main environmental factors affecting the NAI concentration of Quercus variabilis and Platycladus orientalis during the non-growth period were PM 2.5, WS and PM 10, and their variable importance measures were 33.36, 17.58, 14.28, respectively, and 15.89, 17.51, 14.62, respectively. Conclusion The diurnal variation of NAI concentration of Quercus variabilis and Platycladus orientalis in growing period both showed a single peak curve; the diurnal variation of NAI concentration of Quercus variabilis plantations was not obvious, while the diurnal variation NAI concentration of Platycladus orientalis plantations showed a single peak curve in non-growing period. There were significant differences in NAI concentration between Quercus variabilis and Platycladus orientalis plantations, NAI concentration of Quercus variabilis was higher than that of Platycladus orientalis during the growing period, while NAI concentration of Quercus variabilis was lower than that of Platycladus orientalis during the non-growing period. The NAI concentration of Quercus variabilis was higher than that of Platycladus orientalis during the observation period. Differences of environmental factors affecting NAI of typical plantations in the area were obvious. VPD and PAR were the key factors during the growing period, while PM2.5, PM 10 and WS were the key factors during the non-growing period.
The Effects of Stand Structure of Quercus wutaishanica Forests on the Biomass of Different Plant Layers in the Liupan Mountains of Northwest China
ZHANG Xue, LIU Bing-bing, WANG Yan-hui, YU Peng-tao, DUAN Wen-biao, ZHANG Jun
, Available online  , doi: 10.12403/j.1001-1498.20220479
Objective To quantify the effects of stand density and canopy density on the biomass of different plant layers (overstory tree layer, understory plant layer, and litter layer) of Quercus wutaishanica secondary forests in the Liupan Mountains of Ningxia in northwest China, and to determine the optimal stand structure that can maintain the biomass of each layer at a relatively high level for fully using the multiple forest ecosystem services. Method Using sample plot data obtained from field survey, the response of biomass in each layer of Quercus wutaishanica forests to stand density and canopy density were determined by upper boundary lines (UBL) analysis. Then these UBLs were superimposed to find an optimal canopy density range. Result With the increase of canopy density and stand density, the overstory tree layer biomass increased rapidly at first, reaching 292.3 and 296.9 t·hm−2 when the canopy density was 0.75 and the density was 1050 trees∙hm−2, respectively (80% and 82% of the UBL predicted maximum), and then the growth rate slowed down; the understory plant biomass decreased slowly first, and reached 9.08 and 9.17 t∙hm−2 when the canopy density was 0.75 and the density was 1 150 plants∙hm−2, which were 89% and 86% of the maximum value of UBL, respectively. Then it decreased rapidly; the litter layer biomass increased rapidly at first, and reached 33.34 t∙hm−2 when the canopy density was 0.75, which was 97% of the maximum value of UBL. Therefore, the canopy density should be maintained at about 0.75-0.79 in order to keep the biomass of each layer of the stand above 80% of the maximum value of UBL. Conclusion In order to maintain the biomass at relatively high level for all different plant layers of Quercus wutaishanica forests in Liupan Mountains, the canopy density should be maintained at about 0.75-0.79, which will be helpful for guiding the multifunctional management of Quercus wutaishanica forests in the study region and similar areas.
Differences in the Response of Radial Growth of Three Quercus species to Climatic Elements at the Northern Edge of the Warm Temperate Zone and Prediction
WANG Qi, SUN Jing-yi, LIU Jian-feng, CHANG Er-mei, FENG Jian, ZHANG Xiao-fang
, Available online  , doi: 10.12403/j.1001-1498.20230025
Objective The aim of this study was to compare the differences of growth responses of different Quercus species to climatic factors in the same climatic region, and pay special attention to the differences among populations distributed in the same region but belonging to different margins of tree species distribution. Methods The response of radial growth of three dominant deciduous Quercus species (Quercus mongolica, Q. variabilis and Q. acutissima) to climatic factors in the northern margin of warm temperate zone in China was analyzed by dendrochronological method. At the same time, the relationship between radial growth and climate of three tree species was constructed by using mixed linear effect model, and their future growth trends were predicted based on future climate scenarios (RCP2.6 and RCP8.5). Results Chronology of Quercus species in the same area presented high similarity, but there were large differences among different areas. In terms of the response of radial growth to climate, the chronology of different Quercus species in the same region and the same Quercus species in different regions are also different. The radial growth of three Quercus species in Beijing was negatively correlated with the current June temperature, but there was no significant correlation with the temperature in Xianrendong (Liaoning Province). The radial growth of Q. acutissima in Beijing, Q. mongolica in Hebei and Q. variabilis in Dahei Mountain (Liaoning Province) were all limited by precipitation. The modeling results showed that by the end of this century, the radial growth of Quercus species in Beijing and Dahei Mountain would show a decreasing trend, while the trend in Xianrendong (Liaoning Province) would show an increasing trend. Conclusion There are significant differences in the growth responses of Quercus species to climate factors in different areas of the northern margin of warm temperate zone in China, which are mainly dominated by the climate features of sampling regions. In the next step, it should be necessary to clarify the relative contribution of various environmental factors (e.g., stand features and site factors) to radial growth of Quercus species.
Chloroplast Genome Phylogeny and Codon Preference of Anabasis aphylla L.
Huang Xiang, Sulaiman Shah, He Meng-yao, Jiang Ping
, Available online  , doi: 10.12403/j.1001-1498.20220578
Objective To analyze the structural characteristics of Anabasis aphylla chloroplast genome, clarify the taxonomic status of Anabasis in Chenopodiaceae for further exploring its codon preference and determining the optimal codon. Method Total genomic DNA was extracted from fresh assimilation twigs of A. aphylla based on CTAB method. Sequencing was performed using the Illumina HiSeq 2000 high-throughput sequencing platform. The chloroplast genome sequence was assembled and annotated by GetOrganelle and Plann. Simple sequence repeat (SSR) in chloroplast genome was analyzed by MISA. Multiple sequence alignment and ML phylogenetic tree construction were analyzed using MAFFT v.7.450 and IQ-TREE v.2.1.1 software. The nucleotide polymorphism values were calculated using DnaSP 6.0 software. The codon preference was studied by CUSP and Codon W 1.4.2. software. Result The full-length chloroplast genome of A. aphylla was 154 084 bp, including a large single copy region (LSC, 85 124 bp), a small single copy region (SSC, 18 934 bp), and a pair of inverted repeat regions (IRa and IRb, 25 013 bp). A total of 132 genes were annotated, including 83 protein-coding genes, 8 rRNA genes, 37 tRNA genes and 4 pseudogenes. The number of SSRs located in the intergenic region was the largest (70.4%), and the number of single-base (A/T) repeat type SSRs was the largest. The optimal model of phylogenetic tree was TVM + F + R3, and Chenopodiaceae was divided into four clustering groups. Among them, A. aphylla showed the closest relationship with Haloxylon and Salsola. TrnS-trnG(exon1)、ndhF-rpl32rpl32-trnLrps16(exon1)-trnQ and ycf1 were high nucleotide polymorphism regions. A total of 20 optimal codons (UUU, UAU, UGU, CAU, UCU, UCA, UUA, CUU, CCU, AGA, GAA, ACU, ACA, AAU, GAU, AAA, GUU, GCU, GGU, CAA) were determined, all ending with A/U. The codon usage preference was mainly affected by natural selection, and the influence of mutation and other influencing factors was weak. Conclusion The chloroplast genome structure of A. aphylla is conservative, showing typical quadripartite structure. In the phylogeny of Chenopodiaceae, A. aphylla has the closest relationship with Haloxylon and Salsola. The identified hypervariable regions and SSR loci can be used for molecular identification of intergeneric species in Chenopodiaceae. The codon of the chloroplast genome of A.aphylla prefer endings with A/U, and the 20 optimal codons determined are useful for the optimization of its exogenous codons. The results can provide a reference for molecular marker development, phylogeny and chloroplast gene engineering of A. aphylla.
Reproductive Behavior of Monochamus saltuarius (Coleoptera: Cerambycidae)
WANG Jue, SHI Yong, FAN Li-chun, ZHANG Yan-long, ZHENG Ya-nan
, Available online  , doi: 10.12403/j.1001-1498.20220203
Objective To clarify the reproductive characteristics and regulation of Monochamus saltuarius, in this study, the reproductive behavior of the adults of M. saltuarius under laboratory conditions was observed and analyzed, which is helpful to study the control strategies on the basis of its reproductive characteristics. The population density of the next generation can be reduced by inhibiting or delaying the mating of the M. saltuarius. Method After nutrition supplementation, the 3-day-old one female and one male adults of M. saltuarius were put in a transparent glass jar with segments and branches of P. koraiensis at room temperature, relative humidity 55% ± 5%, lighting conditions 8D:16L. The mounting, mating, gnawing oviposition scars, ovipositing and circadian rhythm of adults were observed continuously until they died. Result The results showed that the mating of M. saltuarius could be divided into three stages: pair-bonding, ejaculation, and post-copulatory guarding. The average mating time per adult was 2.38 ± 0.89 times/day, and the average mating time was 27.86 ± 18.37 min·time−1; the average mating time was 1.74 ± 0.51 times·day−1, and the average mating time was 8.68 ± 4.42 min·time−1 ; Female adults made an average groove of 1.76 ± 0.74 times per day-1, and the average length of groove was 16.25 ± 9.45 min per time-; the average spawning time was 1.87 ± 0.61 times per day, and the average duration of spawning was 16.00 ± 10.04 min per time. When there were three pairs of M. saltuarius in the glass jar, the times of mounting, mating, and gnawing oviposition scars increased, the number of eggs laid decreased, and the average duration of each mating behavior shortened. The reproductive behavior of M. saltuarius had an obvious diurnal rhythm, and both mating and oviposition peaks, among which the peak mating period was 12:00-14:00, and the peak oviposition period of female adults was 14:00-16:00 00. The study also found that during the mating process male adults tried to mate with the dead female adults, homosexual adults tried to mate, and three adults mounted together. Conclusion Under indoor conditions, M. saltuarius begins to reproduce on the 4th day after nutritional supplementation. The mating process can be divided into three stages: pair-bonding, ejaculation, and post-copulatory guarding. The mating and spawning behaviors of longhorns have diurnal rhythms.
Seasonal Phenology and Population Dynamics of Japanese Pine Sawyer Monochamus alternatus Hope (Coleoptera: Cerambycidae) in Different Regions of Jiangxi Province
PAN You-liang, LIU Qing, PENG Guan-di, CHEN Yuan-sheng, LI Jin, CAO Yang, LIU Xing-ping
, Available online  , doi: 10.12403/j.1001-1498.20220150
Objective The seasonal phenological characteristics and population dynamics of Japanese pine sawyer beetle, Monochamus alternatus Hope (Coleoptera: Cerambycidae), in different regions of Jiangxi province were analyzed to provide the basic data and scientific basis for improving the local population monitoring level and formulating accurate control strategies of this beetle. Method The initial and terminal occurrence periods, activity peak period and the sex ratio of adult M. alternatus were monitored through setting up monitoring plots and installing the attractant traps in pure stands of Masson pine forest in Quannan, Nankang, Wan'an, Nancheng, Wanli and Fuliang along the latitude gradient of about 1° in Jiangxi province. Results The initial occurrence periods of M. alternatus in Jiangxi were from late March to early May, and were obviously delayed from south to north regions. The final appearance periods of this beetle were from early October to early December, and were obviously shorten from south to north regions. The occurrence period of adults M. alternatus lasted for 5-9 months and decreased significantly from south to north regions. Adult activity peak period gradually postponed and the peaks transited from 2 to 1 from south to north regions. The population density of M. alternatus in central Jiangxi were larger than that in southern or northern Jiangxi. The sex ratio of this beetle was 1: 0.74-0.87, showing biased female and no difference was found in different regions of Jiangxi province. There was an obviously positive correlation between trapping amounts of this beetle and the mortality of Masson pine. Conclusion Geographical latitude and local climatic conditions significantly affect the seasonal occurrence and adult activity peak of M. alternatus, and the population density of M. alternatus is positively related with the mortality of their host plant.
Response of Photosynthesis to Low Temperature in Different Provenances of Bruguiera gymnorrhiza
WU Zhong-hua, ZHAO Hao-yang, ZENG Si-jie, ZHU Jun-jie
, Available online  , doi: 10.12403/j.1001-1498.20220455
Objective This study aims to compare the photosynthetic responses and carbon assimilation of the thermophilic mangrove plant Bruguiera gymnorrhiza (L.) Savigny from different regions under chilling stress. Method The 5-year-old seedlings were collected from three different provenances (Futian (FT) in Shenzhen, Yunxiao (YX) in Fujian) and Okinawa (UR) in Japan (the average temperature of the coldest month was 14.1, 13.3, and 16.1 °C, respectively). The seedlings were treated under normal temperature (20 ℃) and chilling temperature (10 ℃). For each treatment, the chlorophyll fluorescence properties and gas exchange were monitored. Result (1) Compared with normal temperature treatment, after 3 days of chill temperature and cold stress treatment, the maximum light energy conversion efficiency Fv/Fm of photosystem II (PSII) in FT, UR, and YX decreased by 39.04%, 25.69%, and 22.83%, respectively. The maximum light energy conversion efficiency Pm of photosystem I (PSI) decreased by 21.80%, 20.19% and 42.84%, respectively. Under low temperature treatment, the proportion of PSII effective photochemical quantum yield Y(II) of UR and YX all decreased, and the ratio of non-regulatory energy dissipation Y(NO) of the three types of B. gymnorrhiza all increased, and the proportion of YX increased the most. The effective photochemical quantum yield Y(I) of PSI of B. gymnorhiza from the three regions decreased significantly, and the proportion of non-regulated energy dissipation Y(NA) of UR and YX decreased slightly. (2) After 4 days of cold damage treatment, net photosynthetic rate Pn of FT, UR and YX decreased by 92.12%, 97.50% and 86.44%, respectively. Transpiration rate (Tr) and stomatal conductance (Gs) also decreased and Pn, Tr and Gs were positively correlated. The stomatal limit value LS of the three types of B. gymnorhiza decreased significantly, while the intercellular CO2 concentration (Ci) increased significantly. (3) Fv/Fm, Pn and water use efficiency were significantly positively correlated with each other. Conclusion Regardless of the photoreaction of photosynthesis or the carbon reaction, B. gymnorhiza from the three provenances show high sensitivity to short-term chilling. PSII was significantly inhibited, while PSI was relatively stable. Mesophyll damages limited the carbon assimilation more than stomata traits. In summary, FT highly suffers from chilling, while YX is less affected. Hence, cold tolerance of mangroves is closely related to the average temperature at the region sites.
Eco-stoichiometry Characteristics of Litter-Soil in Coniferous and Broad-leaved Mixed Forest of Changbai Mountains
CUI Xue, WANG Hai-yan, ZOU Jia-he, QIN Qian-qian, DU Xue, LI Xiang, ZHANG Mei-na, GENG Qi
, Available online  , doi: 10.12403/j.1001-1498.20220226
Objective The ecological stoichiometry of litter-soil at the stand scale was studied to clarify the changes of litter and soil nutrients and their relationship in forest ecosystem, and to provide a scientific basis for the operation and management of natural coniferous and broad-leaved mixed forest. Method Based on the four plots of spruce-fir broad-leaved mixed forest with an area of 1 ha on North slope of Changbai Mountains, soil samples of 0−20 and 20−40 cm and litter samples of the semi-decomposed horizon (F) and completely decomposed horizon (H) were collected. Soil pH, soil organic matter, total nitrogen, total phosphorus, available phosphorus and readily available potassium were determined, and litter standing crop and litter-soil stoichiometric ratios were calculated. The correlation analysis and redundancy analysis were used to study the litter characteristics and their effects on soil nutrients and the stoichiometric ratios in spruce-fir broad-leaved mixed forest. Result The results showed that litter standing crop had a very significant and strong correlation with soil C/N at depth of 0-20 cm (P < 0.01). Litter C, C/P and N/P decreased significantly with increasing litter a strong positive effect on the litter carbon and C/P in F horizon and litter phosphorus in H horizon. The decomposition degree (P < 0.05). The redundancy analysis results showed that litter standing crop in F horizon had stoichiometric ratios of litter nutrients and soil nutrients were C/P > C/N > N/P. Conclusion Litter nitrogen in the H horizon is the critical factor affecting soil pH, soil organic matter, total phosphorus, readily available potassium and C/P ratio in 0−20 cm soil. Litter nitrogen is the main source of total nitrogen in 20−40 cm soil. Therefore, litter nitrogen may be an important factor driving soil nutrient changes in the study area.
Establishment of Tissue Culture System of the Ancient Trees of Platycladus orientalis
Chang Er-mei, Liu Jian-feng, Jia Zi-rui, Li Xiang, Zhang Jian-qiang, Zhao Xiu-lian
, Available online  , doi: 10.12403/j.1001-1498.20220498
Objective This study aims to establish a tissue culture system for ancient Platycladus orientalis for overcoming the difficulties such as non-thoroughness of disinfection and sterilization, sever browning, and weak meristematic ability. Method In this study, the new shoots of about 3,000-year-old P. orientalis were used as explants, and aseptic explants were obtained through disinfection and sterilization. The tissue culture system for ancient P. orientalis was established by selecting the appropriate culture medium and hormone. Result Disinfecting the explants from ancient P. orientalis using 0.3% HgCl2 for 10 min showed the best sterilization effect, with a pollution rate of 25.81% and the survival rate of 54.82%. The effect of using 3% sucrose as the sugar source for the tissue culture medium of ancient P. orientalis was better than that of 3% glucose. The results of antioxidant and adsorbent tests demonstrated that the browning rate of explants was the lowest under the addition of 3.00 g·L−1 active carbon to the explant initiation medium. The optimal primary culture medium for tissue culture of ancient P. orientalis was 1/2MS + NAA 0.2 mg·L−1 + 6-BA 0.1 mg·L−1, with the induction rate of adventitious buds of 32.05%, rapid bud growth, as well as tender green and robust buds. The optimal proliferation medium was 1/2MS + 6-BA 0.05 mg·L−1 + NAA 0.2 mg·L−1 + KT 0.1 mg·L−1, with the proliferation coefficient reaching 1.93, and rapid growth of green and robust buds. The optimal rooting culture medium was WPM + NAA 0.5 mg·L−1 + IBA 0.5 mg·L−1, which achieved a rooting rate of 9.12%, with an average number of roots per plant of 2.67, and an average root length of 1.23 cm. A total of 24 rooting seedlings were obtained. Two months later, red roots appeared in 2 plants, and the tender buds continued to grow. The tissue-cultured rooting seedlings of ancient P. orientalis were successfully obtained. Conclusion The selection of culture medium and the ratio of auxin to cytokinin are important factors for the proliferation and adventitious root formation of ancient P. orientalis. This study provides a reference for tissue culture of other Cupressaceae trees.
Investigation and Analysis on Host Species and Their Resistance Substances to Bacterial Bark Canker of Populus × euramericana
LI Yong, CHANG Ju-pu, GUO Li-min, SUN Shang, YANG Xu-qi, PIAO Chun-gen
, Available online  
Objective To investigate and analyze the host species of bacterial canker of Populus × euramericana, the disease-resistant varieties and the possible disease-resistant substances they contain. Method The host of the pathogen and the resistant varieties were determined by field investigation and inoculation tests. The content of active substances in the bark of disease-resistant and susceptible varieties was analyzed by HPLC. Result The hosts of bacterial pathogen of P. × euramericana canker are P. deltoides, P. × euramericana and Salix matsudana. P. × euramericana cl. 'Zhonglin 46', P. deltoides cl. '2025', P. × euramericana cv. '2001', P. deltoides cl '313', P. deltoides 'Zhonghe-1' and P. deltoides '16-09' were highly susceptible to the bark canker disease; P. × euramericana 'Yukang 1' and P. deltoides '16-10' were highly resistant varieties, P. deltoides '131', P. deltoides '03-59', P. deltoides '02-212' and P. deltoides '03-34' were resistant varieties. Hybrid willows and Salix babylonica are resistant to the pathogen, and Salix × aureo-pendula can be affected, but do not cause serious disease. The HPLC analysis showed that the contents of catechol, benzoic acid and chlorogenic acid in the bark of resistant and highly susceptible poplar varieties were significantly different. The catechol and catechin increased when the hosts were infected by Lonsdalea populi. Conclusion In this study, the host species of bacterial canker of P. × euramericana are determined, and resistant and highly susceptible poplar varieties are screened. It is showed the catechol and catechin are important compound for host to defense the pathogen infection. The results will be helpful to the control of the bacterial disease of poplar.
Effects of Castanopsis kawakamii Forest Litter on Seed Germination of Pinus massoniana
JIA Mei-hua, WANG Zhe, LIU Jin-fu, JIN Meng-ran, HE Zhong-sheng, XING Cong, SHI You-wen, SHEN Cai-xia
, Available online  
Objective To understand the effect of litter of Castanopsis kawakamii natural forest on the competitive intensity of regeneration of Pinus massoniana. Method The allelopathic effects of litter extract of natural forest with different concentration and decomposition degree on seed germination and radicle growth of P. massoniana were studied. Result (1) The main factor affecting the germination of P. massoniana seeds was the degree of litter decomposition. Compared with the blank control, the litter of undecomposed layer and fully decomposed layer had no significant effect on the germination of P. massoniana seeds; the semi-decomposed layer inhibited the germination rate and germination index and promoted the germination potential. (2) The main factors affecting the growth of radicle were the concentration and action time of litter extract, and the effect of undecomposed layer on the whole radicle growth period of P. massoniana seeds was enhanced with the decrease of concentration, but increased with the decrease of concentration, and the promoting effect was the strongest at the concentration of 1 ≤ 100, and the effect of semi-decomposition layer was promoted by low concentration and high concentration, and the intermediate concentration was inhibited by the undecomposed layer. The fully decomposition layer showed promoting effect as a whole, and the promoting effect decreased with the decrease of concentration. (3) Correspondence analysis showed that different decomposition degree-concentration had no significant effect on seed germination of P. massoniana, but had significant correlation with radicle growth. Conclusion The result proves that the litter extract of different decomposition degree has a weak promoting or inhibiting effect on the seed germination of P. massoniana, promotes the growth of radicle at low concentration, and promotes the regeneration of P. massoniana, which will intensify the interspecific competition in the forest, and lead to the inhibition of the natural regeneration of C. kawakamii.