-->Special Issue： Global Change and Ecological Environment

Prediction of potential distribution of Sophora flavescens in China under climate change

2022/4/2 15:08:56

In order to understand the changes of potential distribution of Sophora flavescens in China under the climate change and to explore the relationship between bioclimatic factors and the suitable distribution pattern of S. flavescens, we investigated the distribution pattern of S. flavescens in China under the three climate scenarios(last glacial maximum, current climate, and future climate), and analyzed the dominant ecological factors affecting the growth of S. flavescens with Maximum Entropy Model(MaxEnt)and Geographic Information System(ArcGIS)by collecting the geographical distribution points of S. flavescens combining with 19 ecological factors. The results were as follows:(1)Under the current climate conditions, the average temperature in the warmest quarter(bio10)and the precipitation in the wettest quarter(bio16)were the dominant climate factors affecting the distribution of S. flavescens.(2)The suitable habitat of S. flavescens accounted for 35.90% of the total land area of China. The optimum areas of S. flavescens were mainly distributed between the 800 mm isopyet and the 400 mm isopyet in China.(3)From the last glacial maximum to the future climate, the suitable habitat area of S. flavescens in China gradually decreased, and showed a trend of moving to high latitude.(4)The suitable habitat area of S. flavescens under the current climate was 0.3% less than that in the last glacial maximum, and the suitable habitat area of S. flavescens under the future climate was 0.75% less than that in the current climate. In conclusion, global warming plays a negative role in the potential distribution area of S. flavescens, and leads to the reduction of suitable habitat and the narrowing of actual niche of S. flavescens, which is not conducive to the growth of S. flavescens to a certain extent. The results of this study provide the theoretical basis for the rational distribution of wild conservation and artificial cultivation of S. flavescens.

Potential suitable area of Altingia multinervis predicted by optimizated MaxEnt model

2022/4/2 15:08:56

Altingia multinervis has been listed as a second-class protected plant in China., with high economic and medicinal values. However, its wild germplasm resources have been nearly exhausted due to the strong disturbance of climate change and human activities. Here, we aim to simulate the changes in the geographical distribution pattern of A. multinervis since the last interglacial(LIG)and to explore how climatic factors restrict the potential suitable areas, to provide a reliable scientific basis for habitat protection and cultivation of A. multinervis and its surrounding wildlife. In this study, based on optimized MaxEnt model and ArcGIS software, we simulated the potential suitable areas of A. multinervis and its spatial change pattern. The importance of environmental factors that constrains current geographical distribution was evaluated by percent contribution(PC), permutation importance(PI)and Jackknife test. The results were as follows:(1)The prediction accuracy of the optimized MaxEnt model was extremely high, as indicated by the value of the area under the receiver operator characteristic curve over 0.97. The potential suitable areas of A. multinervis for the present distribution were mainly distributed in the Yangtze River basin at the junction of Guizhou, Sichuan and Chongqing, of which the best suitable area was around Chishui River basin in Guizhou. The key environmental factors affecting the potential distribution of A. multinervis were mean diurnal range(bio2), annual precipitation(bio12), seasonality of precipitation(bio15)and range of annual temperature(bio7).(2)The potential middle-high suitable area of A. multinervis in current was 2.692 6×10⁴ km², in last interglacial(LIG)was 2.277 3×10⁴ km², in the mid-Holocene(MH)was 2.831×10⁴ km², in four future scenarios were 2.159 6×10⁴ km²(2050s RCP2.6), 2.605 1×10⁴ km²(2050s RCP8.5), 2.330 4×10⁴ km²(2070s RCP2.6), 2.460 4×10⁴ km²(2070s RCP8.5), respectively.(3)Under the four future discharge scenarios, the newly increased area of A. multinervis was concentrated in Sichuan and Guizhou, while it was concentrated in Chongqing in the mid-Holocene. All the above results indicate that the distribution range of A. multinervis is narrow and the potential suitable area is very small, and the unique topographic advantage of Chishui River Basin may be the main refuge place of A. multinervis.

Exploring the flowering period change of Meconopsis based on digital specimen

2022/4/2 15:08:57

In the recent years, with the significant increase in global temperature, global warming caused by climate change has attracted widespread attention. Climate warming will change plant phenology, and the changes in flowering period can directly reflect the adaptation of plants to the surrounding environment, especially alpine plants are more sensitive to climate change, therefore, exploring the flowering period of alpine plants is more representative. In order to understand the changing characteristics of the flowering period of plants under the background of climate warming, and to develop reasonable plant protection measures. We took the famous alpine plant Meconopsis as an example, based on the data of 3 056 alpine plant specimens of Meconopsis from 1880 to 2017 kept by the Chinese Virtual Herbarium. Among them, the attributive years of flowering specimens were 104 years, and there were 1 539 specimens of statistical significance. Correlation analysis was used to study the relationship between the flowering period and year of Meconopsis plants distributed in China. The results were as follows:(1)Under the background of climate warming, with the increase of years, the flowering period of Meconopsis showed a trend of postponing.(2)There were differences between species, among them, six species of Meconopsis, including M. integrifolia, M. punicea, M. racemosa, M. henrici, M. lancifolia and M. chelidonifolia, showed a trend of delayed flowering period with the increase of years; the flowering period of three Meconopsis species, M. horridula, M. quintuplinervia and M. impedita showed an earlier trend with the increase of years.(3)Among them, the number of days of delayed flowering period was M. punicea, which was delayed by 6 d on average from 1880 to 2017, and the most advanced number of flowering days was M. impedita, with an average of 5 d in advance from 1880 to 2017. In conclusion, the results of this study indicate that the flowering period of Meconopsis trends to be delayed as a whole under the influence of climate warming, and the flowering period of most species is delayed, while the flowering period of a few species trends to be earlier.

Analysis of elevation pattern of seed flora on the south slope of Budanla Mountain in southern Tibet, China

2022/4/2 15:08:57

The ecotone of ecological communities is usually rich in species and complex in floristic components, which is regarded as a key zone. Budanla Mountain is located in the transition zone of semi-humid to semi-arid ecological environment in Tibet. Because of its special natural geographical environment, it has rich mountain plant diversity. However, the composition and floristic characteristics of seed plants in this important ecological transition area are still not well understood. In order to clarify the floristic composition and vertical distribution pattern of seed plants on the south slope of Budanla Mountain, the floristic characteristics of seed plants on the south slope of this mountain were systematically studied through field plant community quadrat investigation, laboratory specimen identification and related literature review in this paper, the richness pattern of advantage genera and geographical composition along the altitude gradient was also explored. The results were as follows:(1)There were approximately 316 species of seed plants belonging to 45 families and 156 genera in the south slope of Budanla Mountain, in which there were the most abundant single species and small genera of seed plants, the temperate distribution type was dominant at the genus and species level.(2)In the vertical distribution gradient of geographical elements, the temperate distribution type had a peak value at 4 000 m, including 53 genera, and showed a downward trend with the increase of altitude.(3)The nature of floristic geographical elements and the vertical distribution of species richness in this area might be mainly affected by the local semi-humid climate, local environmental factors and topography. The results of this study can provide important basic data for the study of plant diversity protection and resource utilization in this region.

Latitudinal variation of branchlet biomass allocation and functional traits of endangered species Michelia odora and its influencing factors

2022/4/2 15:08:57

In this study, the functional traits of annual branchlets and leaves of Michelia odora, an endangered species, were sampled and measured along five different latitude gradients in Guangxi. The variation of biomass distribution and leaf functional traits along the latitude gradient were discussed. The results were as follows:(1)The total branchlet weight and total leaf weight tended to allometric growth relationship with the increase of latitude, and its biomass tended to the construction of branchlets.(2)The functional traits of the leaves showed a certain rule, i. e. increased with latitude from south to north, and its leaf area and leaf mass decrease of with the increasing latitude; leaf thickness, leaf dry matter content, stomatal length, stomatal area, stomatal density showed a trend of gradual increase; specific leaf area, leaf water content and stomatal width increased at first and then decreased, and overall showed a trend of gradual decrease, leaf tissue density decreased and then increased, which indicates that M. odora can respond to changes in the geographical environment through the plasticity of the leaf shape.(3)Specific leaf area was significantly positively correlated with leaf moisture content, but negatively correlated with leaf fresh weight, leaf dry matter content, and stomatal density. There was a significantly negative correlation between leaf dry matter content and leaf water content, which means that M. odora can respond to the change of geographical environment by adjusting and balancing the character combination of leaves.(4)CCA analysis showed that slope was the most significant variable affecting the functional traits of M. odora, the mean annual temperature also had a significant impact on the functional traits of M. odora, the mean annual precipitation, and relative humidity had a certain intensity effect on plant functional traits, but not significant. All the results are helpful to understand the adaptation characteristics of M. odora to the environment, and its response mechanism to latitude variation is of great significance.

Limiting factors of photosynthesis of Phyllostachys edulis seedlings treated with nitrogen fertilized and change of short-term light irradiance

2022/4/2 15:08:57

In order to understand the limiting factors of photosynthesis of Phyllostachys edulis seedlings under nitrogen addition and change of short-term light irradiance. The light response curve and CO₂ response curve were measured under different short-term light irradiance conditions(high light:1 200 μmol·m^-2·s^-1, low light:200 μmol·m^-2·s^-1), and an improved FvCB model was used to study the photosynthetic characteristics of P. edulis seedlings with nitrogen fertilized. The results were as follows:(1)Biomass of P. edulis seedlings treated with nitrogen fertilized was significantly higher than that of control, and light saturated maximum net photosynthetic rate(P_Lmax), carboxylation efficiency(CE), maximum carboxylation rate(V_cmax)and maximum electron transport rate(J_max)were significantly higher than those of control.(2)CO₂ saturated maximum net photosynthetic rate(P_Cmax), CE, mesophyll conductance(g_m), triose phosphate utilization rate(T_p)and carbon dioxide saturation point(CSP)of P. edulis seedlings under high light level were significantly higher than those of low light level.(3)g_m has no differences after nitrogen fertilized, but it reduced 60.31% while the decrease of short-term light irradiance. In conclusion, P. edulis seedlings with nitrogen treatment increased the quantity and activity of ribulose-1, 5-bisphosphate carboxylase/oxygenase(Rubisco)protease in photosynthesis process, promoted photosynthetic phosphorylation and NADPH synthesis, and improved the reqeneration rate of ribulose-1, 5-bisphosphate(RuBP)through higher V_cmax and J_max, in order to fully assimilate photosynthetic carbon, promote the high growth and biomass accumulation. Therefore, it could be inferred that the content and activity of Rubisco and regeneration capacity of RuBP were the limiting factors of the photosynthesis rate, for the control P. edulis seedlings with no nitrogen. To sum up, light heterogeneity affect the photosynthetic physiological and biochemical changes inside the leaves of P. edulis, the decreasing of light intensity effectively regulate the changes of g_m and T_p, indicating that the photosynthesis of P. edulis seedlings are mainly limited by g_m and T_p. The research shows that nitrogen fertilized and the change of short-term light irradiance affect the photosynthesis and carbon acquisition of P. edulis seedlings, and also affect its growth and regeneration.

Effects of fertigation under equal nitrogen on ratoon yield and nitrous oxide emissions in soil

2022/4/2 15:08:57

In order to get reasonable water and fertilizer management measures, the effects of different fertigation proportions under the same nitrogen(N)rate on the yield of ratoon and nitrous oxide(N₂O)flux and inorganic N content in soil at the different growth stages were studied, the relationships between soil N₂O flux and inorganic N content were analyzed. Taking natural rainfall(W₀)as the control, two drip irrigation levels, W₁(75% of field water capacity)and W₂(85% of field water capacity)and four fertigation proportions at the same N rate(N 300 kg·hm^-2), F₁₀(100% basal fertilizer), F₅₅(50% basal fertilizer, 50% fertigation topdressing), F₃₇(30% basal fertilizer, 70% fertigation topdressing)and F₁₉(10% basal fertilizer, 90% fertigation topdressing)were designed. Agronomic traits(stalk weight, plant height, stalk diameter and effective stalks per hectare)and yield of sugarcane, the N₂O flux and the contents of nitrate, nitrite and ammonium nitrogen in soils at the three growth stages were determined. The results were as follows:(1)The ratoon yields in W₁F₅₅ and W₂F₅₅ were higher, i.e. 102.4 t·hm^-2 and 97.8 t·hm^-2, respectively; Soil N₂O emission flux in F₅₅ was lower under the same irrigation amount.(2)There was a significant negative correlation between soil N₂O flux and ammonium nitrogen content, with a correlation coefficient of -0.497(P<0.05, n=24); A reasonable fertilization proportion with drip irrigation can effectively increase sugarcane yield and reduce soil N₂O emission. Therefore, the treatment with a fertigation proportion of 5:5 under the same N rate can not only have a relatively high yield of ratoon, but also reduce the N₂O emission from the sugarcane soil.

Effect of inorganic nitrogen supply on the salt-tolerance of Brassica napus plantlets in vitro

2022/4/2 15:08:57

The Brassica napus(Bn)plantlets in vitro were used as the experimental materials in this study. The sodium nitrate was employed to provide the sole nitrogen source and salt stress. The growth parameters, chlorophyll contents and foliar δ¹³C of B. napus plantlets were measured in this study. The photosynthetic capacity of B. napus plantlets was estimated by the stable carbon isotope value. The relationship between inorganic nitrogen supply and salt-tolerance of the B. napus plantlets was studied based on the photosynthetic capacity. The results were as follows:(1)The deleterious effect of slight salt stress could be counteracted by 40 mmol·L^-1 sodium nitrate, while the deleterious effect of moderate salt stress could be effectively relieved by 80 mmol·L^-1 sodium nitrate. However, even if the inorganic nitrogen supply was excessive, the growth of B. napus plantlets was heavily inhibited by the severe salt stress.(2)The chlorophyll contents of B. napus plantlets decreased gradually with increasing salt stress.(3)The photosynthetic capacity of B. napus plantlets reached the maximum under slight salt stress condition. However, the photosynthetic capacity of B. napus plantlets decreased obviously with increasing salt stress. Hence, when the inorganic nitrogen demand is met for plants, the salt-tolerance of plants will depend on the photosynthetic capacity. Excessive inorganic nitrogen supply can not improve the photosynthetic capacity of plants suffered from the severe salt stress.

Temporal and spatial distribution characteristics of naturalized plants in West China

2022/4/2 15:08:57

Naturalization is the basic premise for exotic plants to surmount a series of obstacles and become invasive plants. It is helpful to prevent and control plant invasion for studying the species composition and distribution of naturalized plants. Based on literature reports and specimen records, we firstly maked statistics on naturalized plants in 126 prefecture-level cities in 12 provinces(regions)in West China, included all vascular plants, and analyzed the plant composition and temporal and spatial distribution characteristics. The results were as follows:(1)There were 826 species of naturalized plants belonging to 107 families and 473 genera in the western region, accounting for about 75.16% of 1 099 species of naturalized plants in the country.(2)In terms of time, according to regression fitting, the cumulative growth of naturalized plants in the western region was stable before the 15th century, and then showed a Logistic pattern of growth, and the growth rate was the largest in 1936. At present, the growth rate slowed down but the proportion of unintentional introduction was significantly higher than that in other periods.(3)Spatially, the number and density of species were increasing from northwest to southeast and inland to the border, and there was a phenomenon of strong provincial capitals.(4)Regression tree analysis showed that annual precipitation, GDP, average annual temperature and cropland ratio were the main driving factors for the distribution pattern of naturalized plants in the western region. These results enriches the basic data of naturalized plants in the western region, are conducive for finding out the current situation of alien plant invasion in the western region, and provide scientific basis for its comprehensive control.

Analysis on the differences of light utilization strategies of four Poaceae species with different evolution degrees in the south subtropical region of China during summer period

2022/4/2 15:08:57

In order to explore the light energy utilization strategy of four Poaceae species, including sugarcane, carpet grass, bulrush and buddha bamboo, the plants in the field or original habitat were used as materials. We determined the chlorophyll fluorescence and photosynthetic gas exchange characteristics from fresh seedlings leaves in vivo, and analyzed the pigment contents during the hottest period of the summer. The results were as follows:(1)The C₄ sugarcane and carpet grass had high net photosynthetic rate(P_n)coupled with high water use efficiency(WUE)and high quantum yield efficiency(Φ_i), thus being able to assimilate a large fraction of light energy;(2)The C₃ bulrush had relatively high P_n, WUE and Φ_i, and its high carotenoid pool which coupled high nonphotochemical quenching heat dissipation(NPQ)might help the bulrush to get rid of the excessive light energy;(3)The C₃ buddha bamboo had the lowest P_n, WUE and Φ_i, however, its large carotenoid contents and high xanthophyll de-epoxidation level(DPS), coupled with high NPQ were expected to help the leaves to dissipate the excess light energy. In addition, the light-use strategies of the four species were also affected by their life forms. These findings are expected to help breeding programs for sugarcane, carpet grass and buddha bamboo, and to provide a physiological reference for wetland ecological restoration and planning of bulrush.

Distribution pattern of plant community and its relationship with environmental factors in Qilian Mountains National Nature Reserve of Gansu Province

2022/4/2 15:08:57

The distribution pattern of plant community is the result of the interaction of environmental factors and human activities, especially the elevation gradient is considered as the decisive factor of the distribution pattern of plant community. In order to explore the relationship between plant community distribution pattern and environmental factors and its driving mechanism in Qilian Mountains National Nature Reserve of Gansu Province, the characteristics of plant community and its relationship with environmental factors in the study area were disucssed, using quantitative classification and DCCA sequencing methods on the basis of field investigation. The results were as follows:(1)There were 85 species of seed plants belonging to 30 families and 56 genera in 88 sampling plots of Qilian Mountains National Nature Reserve of Gansu Province, including twelve species of Gramineae, nine species of Compositae, eight species of Fabaceae, six species of Rosaceae and five species of Chenopodiaceae, accounting for 14.11%, 10.59%, 9.41%, 7.06% and 5.88% of total species, respectively. These plants could be classified into nine plant communities throught TWINSPAN.(2)Nine plant communities were clustered and distributed on the DCCA sequencing diagram, showing a good environmental gradient. Altitude had a great influence on the distribution pattern of plant communities, followed by precipitation, temperature, slope, slope direction and soil humus.(3)Among the variables influencing plant community spatial distribution pattern, environmental factors accounted for 25.24%, spatial factors accounted for 13.21%, space factor and environment factor interactions accounted for 9.03%, 52.52% of the community distribution pattern was not accounted by spatial factor and environmental factor section, and this part mainly reflected the human activity influence on plant community distribution pattern in the study area. The results of this paper are of great significance to the ecological restoration of vegetation and the stable maintenance of biodiversity in the region.

Displacement distribution and climate explanation on humid and semi-humid evergreen broadleavedforests using niche model of Cyclobalanopsis glauca and C. glaucoides in China

2022/4/2 15:08:57

To explain the geographical displacement law and the dominant climate variables between humid evergreen broadleaved forests(HEBF)and semi-humid evergreen broadleaved forests(SHEBF), Cyclobalanopsis glauca and C. glaucoides were selected as research objects because the both species are the typical dominant tree species of the HEBF and SHEBF, then the specimens data of the both species and the 19 bio-climate variables map layer were collected to simulate their distribution area using MaxEnt model. Moreover, the niche differences were quantitatively analyzed by the kernel density analysis, discriminant function analysis(DFA)and analysis of variance(ANOVA)to reveal the dominant climate variables which affect the niche differentiation between the both species, then the geographical displacement law and the dominant climate variables between the HEBF and SHEBF were analyzed. The results were as follows:(1)The AUC values of C. glauca and C. glaucoides were 0.995 and 0.986 respectively, which accurately predicted the potential distribution of the both species; C. glauca was suitable for the subtropical and north-tropical regions of 20°to 30° N, but C. glaucoides was mainly distributed in subtropical area of Yunnan-Guizhou Plateau.(2)The results of DFA and ANOVA were consistent, and the mean diurnal range(bio2), isothermality(bio3)and the precipitation seasonality(bio15)were the climate variables that promoted the niche differentiation of the two species.(3)Kernel density analysis showed the mean diurnal range(bio2), isothermality(bio3)and temperature seasonality(bio4)were the dominant temperature variables affecting the niche differentiation of the both species; and the precipitation seasonality(bio15), annual precipitation(bio12), precipitation of the driest month(bio14), precipitation of the driest quarter(bio17)and precipitation of the coldest quarter(bio19)also significantly affected the niche differentiation of the both species. All the above results indicate that isothermality, the seasonal differences of temperature and precipitation are the main variables determining geographical displacement distribution of the HEBF and SHEBF from the niche simulation of C. glauca and C. glaucoides.

Heavy metal pollution and health assessment in sediments of Kandelia obovata wetlands of different origins

2022/4/2 15:08:57

Heavy metal pollution in Kandelia obovata ecosystem is an important part of coastal wetland research. In order to explore the health risk and heavy metal pollution of K. obovata wetland of different origins in eastern Fujian, this study explored the content characteristics of heavy metals in surface sediments of different origins of K. obovata wetlands and assessed their health risks in East Fujian by using the pollution load index method and human health risk assessment method. The results were as follows:(1)The average contents of heavy metals in surface sediments of K. obovata natural forest wetlands were Zn(102.38 mg·kg^-1)> Pb(101.53 mg·kg^-1)> Cu(11.72 mg·kg^-1)> Cd(0.91 mg·kg^-1). The order of heavy metal contents in surface sediments of K. obovata plantation was Zn(152.81 mg·kg^-1)> Pb(105.83 mg·kg^-1)> Cu(16.38 mg·kg^-1)> Cd(1.33 mg·kg^-1).(2)The regional pollution load index(I_{PL zone})of heavy metals in surface sediments of K. obovata natural forest was lower than that of K. obovata plantation, and the corresponding pollution levels of K. obovata plantation and natural forest were both one, which belonged to moderate pollution.(3)The non-carcer risk(RN)of heavy metals in surface sediments of K. obovata wetlands to adult males and adult females was lower than one, and the RN to human body was very low. The RN of Pb element to children was higher than one, it would cause RN to children. The carcer risk(cancer risk, RI)of Cd to adult males, adult females and children was greater than 1.0×10^-6, and there was a serious RT to the human body. The results indicate that heavy metal pollution of wetlands in East Fujian was serious. Therefore, we should control the pollutant emission around the wetland and purify the wetlands. In addition, adding the health risk assessment of heavy metals to the evaluation of K. obovata wetland ecosystem will help to strengthen the ecological protection and risk management of K. obovata.

Heavy metal enrichment of dominant plants in Niujiaotang mining area of Guizhou Province

2022/4/2 15:08:57

To select suitable materials for remediation of heavy metal pollution in karst areas of Guizhou Province and ecological reclamation of mining area. A total of 30 dominant plants and their root soils were collected in Niujiaotang lead-zinc mining area of Guizhou Province for testing of the contents of Cd, Cu, Ni, Pb and Zn in aboveground, underground and root soils. The enrichment and transport coefficients of heavy metals by plants were calculated, and the application potential of plants was comprehensively evaluated by cluster analysis. The results were as follows:(1)Cd contents in the aerial part of Senecio scandens and Bidens Pilosa were respetively 40.33 mg·kg^-1and 43.26 mg·kg^-1, the enrichment coefficients(aboveground part)were respectively 0.20 and 0.37, and the transport coefficients were respectively 1.35 and 1.16, and they had strong ability to enrich Cd and had certain remediation potential for Cd contaminated soil.(2)The contents of Cd and Zn in aboveground of Polygonum capitatum were 77.49 mg·kg^-1 and 3 557.96 mg·kg^-1 respectively, which were the maximum values among the 30 plants investigated in this survey. It is a potential plant material for remediation of Cd and Zn contaminated soil.(3)The content of Ni in aboveground of Buddleja lindleyana was 0.62 mg·kg^-1, and the enrichment coefficient(aerial part)and transport coefficient were 6.16 and 1.37 respectively. However, a further study need to be done to test whether the plant for Ni enrichment.(4)The contents of Cd, Cu, Pb and Zn in the roots of Mirabilis jalapa and Equisetum ramosissimum were much higher than those in aboveground, which were root-hoarding plants. The contents of Cd, Cu, Zn and other heavy metals in aboveground and underground parts of Indigofera bungeana were relatively low, which belonged to evading plant. Therefore, Senecio scandens, Bidens pilosa, and Polygonum capitatum can be used to remediate heavy metal pollution in soil, and Mirabilis jalapa, Equisetum ramosissimum, and Indigofera bungeana can be used for reclamation of mining area.

Analysis of microbial diversities and enzyme activities of rhizosphere soil of Pennisetum giganteum(giant juncao) under different degrees of saline-alkali stress

2022/4/2 15:08:57

Salinty and alkali are the serious stress in arid and semiarid area, which has a bad effect on plant growth. It is necessary for us to explore the variety of microbial community and the activity of enzyme in rhizosphere of Pennisetum giganteum(giant juncao)under saline-alkali environment. As a result, we set up the experiment with seven different kinds of saline-alkali concentrations, analyze the difference significance and correlation of physiological data under different saline-alkali concentrations with the method of SPSS, and analyzed the diversities of microbial communities with the method of Illumina high-throughput sequencing. The results were as follows:(1)The composition of microbial communities in rhizosphere soil of giant juncao differed at different saline-alkali stresses; The dominant groups were Sordariomycetes(68.5%), Eurotiomycetes(16.3%), Chloroflexia(8.5%), Bacteroidia(13.5%), Gemmatimonadetes(5.6%)and δ-Proteobacteria(3.7%)at the 12‰ saline-alkali concentration; The relative abundance of the Dothideomycetes(27.7%)and Anaerolineae(2.4%)was sharply reduced to 2.5% and 0.007% when the saline-alkali concentration increased from 6‰ to 12‰; The Chao and Shannon indexes of the rhizosphere microbial community of giant juncao decreased with increasing saline-alkali concentration, and were significantly correlated with soil saline-alkali concentration(P<0.01).(2)The low concentration of saline-alkali stress had a positive effect on activities of urease, polyphenol oxidase and alkaline phosphatase in rhizophere soil of giant juncao, but activities of polyphenol oxidase, alkaline phosphatase and sucrase were inhibited when the saline-alkali concentration of soil exceeded 8‰; After planting giant juncao, the content of soil organic matter increased significantly(P<0.05)and the saline-alkali concentration were reduced significantly(P<0.05); The neutralizing ability to soil alkalinity gradually weakened with the increasing saline-alkali concentration, and the neutralizing ability of soil salinity gradually weakened when the concentration exceeded to 8‰; When the saline-alkali concentration was 6‰, the production of giant juncao was the highest and the soil had higher contents of available nutrients and organic matter. The research indicates that growing giant juncao is beneficial to improving the fertility of saline-alkali soil by adjusting the enzyme concentration to better adapt to the medium and low concentration saline-alkali soil environment, and producing the corresponding dominant flora to adapt to the environment in different degrees of saline-alkali soil.

Ecological adaptability of endangered plant

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Bhesa robusta is a critically endangered plant in China, which also is an important component of natural vegetation in the coastal ecotone of Guangxi. In order to learn about whether the light factor has the effects on the natural regeneration of B. robusta saplings or not, the interannual variation characteristics of physiological and growth indexes of B. robusta saplings under three different photosynthetic habitats of forest edge, forest gap, and understory were studied. The results were as follows:(1)The deficiency of photosynthesis active radiation affected the growth of B. robusta saplings, the growth of ground diameter, plant height, and leaf area of understory saplings decreased significantly, while the growth index of saplings growing in the forest edge with sufficient light was the largest.(2)With the decrease of photosynthesis active radiation, the contents of superoxide dismutase(SOD)and catalase(CAT), soluble protein, relative electrical conductivity, and malonaldehyde(MDA)of the B. robusta saplings under forest edge habitat were significantly higher than those in the understory habitat, and the free proline content of B. robusta sapling under the understory habitat were significantly higher than in forest edge and forest gap habitat.(3)With the decrease of photosynthesis active radiation, the photosynthetic pigment index chlorophyll a, chlorophyll b, carotenoids of B. robusta sapling were increased in the understory habitat, and the chlorophyll a/b ratio of B. robusta sapling was higher in the forest edge habitat; The net photosynthetic rate(P_n)and transpiration rate(T_r)on the photosynthesis physiological target of B. robusta saplings in forest edge habitat were higher than those in understory and forest gap habitats; The intercellular CO₂ concentration(C_i)and water use efficiency(WUE)of B. robusta sapling in the understory were higher than those in forest gap and forest edge habitats. And WUE was the highest in the forest edge habitat from February to April, WUE of B. robusta saplings in the understory habitat were higher than those of the other two habitats in June to October, and there were almost no differences between the three habitats in December. All the above results indicate that the light factor is one of the limiting factors during the growth period of B. robusta sapling, and the growth of B. robusta sapling in the forest edge habitat is significantly better than that in the forest gap and understory habitats because of the abundant sunlight.

Bhesa robusta sapling in different habitats

2022/4/2 15:08:57

Plant species can adapt to heterogeneous habitats through variations in functional traits. For the plants with different growth forms, how to adjust their phenotypes to adapt to the environment has been one of the core topics in ecology. To clarify the response mechanisms of plant species with different growth forms to heterogeneous habitats in south subtropical forests, we measured a total of eight functional traits involving four structural traits(leaf thickness, leaf length/width ratio, leaf dry matter content and specific leaf area)and four stoichiometric traits(leaf nitrogen content, leaf phosphorus content, SymboldA@ ¹³C and SymboldA@ ¹⁵N)of five dominant trees(2 canopy species and 3 understory species)and their diameter at breast height, in 27 quadrats(20 m × 20 m)at different elevations and convexity along three mountain ridges within the 20 hm² south subtropical evergreen broad-leaved forest plot at Dinghu Mountain in Guangdong Province. We analyzed and compared the differences in responses of the canopy and understory species to different elevations and convexity in terms of functional traits. The results were as follows:(1)There existed some leaf functional traits in each tree species that were significantly correlated with altitude, but for convexity, only the leaf area of Cryptocarya chinensis was positively correlated with convexity and the leaf nitrogen content of Blastus cochinchinensis was negatively correlated with convexity.(2)Specific leaf area, leaf thickness and SymboldA@ ¹⁵N were generally more responsive to elevation, while leaf length/width ratio and leaf dry matter content were less responsive.(3)There were significant differences in specific leaf area, leaf dry matter content and leaf nitrogen content between canopy and understory tree species in heterogeneous habitats. Compared with canopy tree species, understory tree species had lower leaf thickness, leaf dry matter content and SymboldA@ ¹³C. Moreover, canopy and understory species responded to elevation and convexity to different extents, with understory species having more functional traits with significant differences in different types of habitats. The results indicate that the degree of response to the environment varied greatly between plants with different growth forms, i.e., the dominant understory tree species had greater plasticity in the heterogeneous habitats than the dominant canopy species in the forest plot. In addition, specific leaf area, leaf thickness and SymboldA@ ¹⁵N are important and effective traits indicating plant adaptation and responses to the environment in the south subtropical evergreen broad-leaved forest.

Population structure and dynamics analysis of rare and endangered plant Camellia kweichowensis

2022/4/2 15:08:57

Camellia kweichowensis is a rare 5-locular capsule-bearing representative species of the section Camellia with biological importance and economic value. In order to explore the reasons for its endangered status, we studied the quantitative characteristics of population structure dynamics and future development trend by combining the sample investigation and actual measurement methods, the analysis of population age structure and survivability. The results were as follows:(1)The primary vegetation of C. kweichowensis had typical characteristics of subtropical humid evergreen broad-leaved forests. While the mixed evergreen and deciduous broad-leaved forest were the main stands, and the coniferous broad-leaved mixed forest of Pinus armandii + Betula luminifera + Liquidambar formosana + Nyssa sinensis + Camellia sp. + Eurya sp. + Schima sp. was common.(2)The growth population of C. kweichowensis dominated the growth structure. The points were mainly concentrated in the small and medium tree stages, and the sum of the proportion constituted 73.02% of the overall population. Deevey-Ⅱ type characteristic of the population survival curve was obvious, the life expectancy of C. kweichowensis was the maximum at the seedling stage. The change trend of mortality and the vanishing curves of the same plot were approximately the same. The quantitative dynamic analysis indicated that the three plots had abundant seedling pools, but were sensitive to the disturbance outside the habitat. The probability of surviving to Ⅶ age-class dropped significantly to 36.17%. On the whole, the population structure showed the characteristics of “growth in the early stage and decline in the late stage of Ⅳ age-class”.(3)After the growth period of 2, 4, 6, 8, and 10 diameter scales, the C. kweichowensis population dynamics tilted toward the succession of middle trees(Ⅴ-Ⅶ age-class), big trees(Ⅷ-Ⅹ age-class), and aged trees(Ⅺ-ⅩⅢ age-class). In conclusion, due to the limited habitat resources and space, intraspecific and interspecific competition intensifies, which reduces the survival rate of population seedlings and the number of young, and increased the mortality of adult plants caused by human predatory logging. As a result, the population renewal and diffusion are hindered, the distribution area is narrow, and the species tend to be endangered.