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Table of Content

    10 March 2021, Volume 40 Issue 3
    Effects of source-sink manipulation on the accumulation and translocation of nonstructural carbohydrates in stems and sheaths of Japonica rice under elevated CO2 concentration and different nitrogen fertilization levels.
    ANG Jing-rui, CAO Pei-pei, YANG Kai, LYU Chun-hua, WANG Yi-jie, SUN Wen-juan, YU Ling-fei, HU Zheng-hua, HUANG Yao
    2021, 40(3):  615-626.  doi:10.13292/j.1000-4890.202103.007
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    We investigated the effects of source-sink manipulation on the accumulation and translocation of non-structural carbohydrates (NSC) in the stems and sheaths of a Japonica rice (Oryza sativaL.) cultivar “Nangeng 9108” under elevated CO2 concentration (\[CO2\]) and different nitrogen (N) fertilization levels. There were two CO2 concentrations-ambient \[CO2\] (a\[CO2\]) and a\[CO2\]+200 μmol·mol-1 (e\[CO2\])-in open-top chambers (OTCs), and three N application rates, low N (N1, 10 g N·m-2), medium N (N2, 20 g N·m-2), and high N (N3, 30 g N·m-2). The source-sink manipulations were carried out by leaf cutting (LC) and spikelet removal (SR). No source-sink manipulations were set as control (CK). Leaf N content and the total mass of NSC stored in stems and sheaths (TMNSC) at heading and maturity were measured. The apparent transferred mass of NSC from stems and sheaths to grains (ATMNSC) and the apparent contribution of transferred NSC to grain yield (ACNSC) were calculated. The results showed that e\[CO2\] significantly decreased leaf N content at heading stage, and significantly promoted NSC accumulation at the N2 level. Under different \[CO2\] and N levels, SR treatment increased TMNSC at maturity but decreased ATMNSC and ACNSC. LC treatment significantly decreased TMNSC and increased ATMNSC at maturity under a\[CO2\] and different N levels. There were no significant effects of LC treatment on TMNSC and ATMNSC at maturity under elevated CO2. The LC treatment did not affect grain yield and its components. We found higher ratio of spikelet number to leaf area (grain/leaf ratio), higher ATMNSC, ACNSC, grain yield and harvest index but lower TMNSC and 1000grain weight at maturity. The factors affecting ACNSC were grain/leaf ratio, and TMNSC at heading and maturity, while those affecting grain yield were grain/leaf ratio, leaf N content and TMNSC at maturity. The relationships between ACNSC and grain yield can be quantified by multiple regression models.
    Biochar regulates the salt tolerance of rice seedlings under salt stress.
    HUANG Jing, KONG Ya-li, WU Long-long, ZHANG Lu, ZHU Lian-feng, CAO Xiao-chuang, ZHU Chun-quan, ZHANG Jun-hua
    2021, 40(3):  627-634.  doi:10.13292/j.1000-4890.202103.030
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    Salinization reduces the productivity of soils. Exploring the effects of biochar on salt tolerance of rice seedlings under salt stress is important to regulate rice production potential in saline areas. In this study, the effects of biochar on soil environment and salt tolerance of rice seedlings under salt stress were examined in a pot experiment. There were four levels of salt concentrations: 0 g NaCl·kg-1 soil (S0), 1 g NaCl·kg-1 soil (S1), 2 g NaCl·kg-1 soil (S2), and 3 g NaCl·kg-1 soil (S3). There were two levels of Biochar applications: 0 g biochar·kg-1 soil (C0) and 3 g biochar·kg-1 soil (C1). The results showed that biochar application in salt stressed soil significantly increased aboveground biomass and agronomic characters of rice seedlings. Biochar application significantly increased total K content in the stem of rice seedlings and enhanced K/Na ratio in rice seedlings by 79.61%. Biochar application greatly improved the antioxidant abilities of rice seedlings and reduced the MDA content of leaves by 14.25%. Biochar application inhibited membrane lipid peroxidation of rice seedlings and alleviated the negative effects of salt stress on rice seedlings. After the harvest of rice seedlings, soil watersoluble Cl- and Na+ contents under biochar treatments were significantly decreased by 9.13% and 17.77% respectively. Our results showed that applying appropriate amount of biochar in the soil can effectively reduce soil watersoluble salt content, improve the salt stress of soil, and enhance the adaptability of rice seedlings to the saline soil.
    Effects of stand age on soil greenhouse gas flux in Korean pine and larch plantations.
    PEI Yu, ZHANG Yue, GENG Shi-cong, FENG Yue, ZHANG Jun-hui
    2021, 40(3):  635-643.  doi:10.13292/j.1000-4890.202103.014
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    Studies on soil greenhouse gas emission and its mechanism in the process of plantation development can provide theoretical basis for estimating forest greenhouse gas flux. We examined the soil greenhouse gas emission and absorption rate of Korean pine (Pinus koraiensis) and larch (Larix gmelinii) plantations with different stand ages (15, 30 and 50 years old) in Maoer Mountain of Heilongjiang Province, using laboratory incubation method. The results showed that soil CO2 emission rates (Korean pine: 1724.18±98.57 μg C·kg-1·h-1; larch: 1306.37±142.27 μg C·kg-1·h-1) and CH4 absorption rates (Korean pine: 5.12±0.68 μg C·kg-1·h-1; larch: 1.91±0.85 μg C·kg-1·h-1) were significantly higher in 30-year-old plantations than that in 15 and 50-year-old plantations. Soil N2O emission rate of 30-year-old Korean pine plantation was significantly higher than that of 15 and 50-year-old Korean pine plantation (P<0.05). Soil N2O emission rate in the larch plantations did not change across stand ages. The maximum soil N2O emission rates were (0.139±0.016) μg N·kg-1·h-1 in Korean pine plantation and (0.137±0.056) μg N·kg-1·h-1 in larch plantation, respectively. Soil CO2 emission rates were higher in Korean pine plantations of all stand ages than in larch plantations in 15 and 30-year-old plantations. For all stand ages, soil CH4 absorption rate was significantly higher (P<0.05) in Korean pine plantations than in larch plantations. Soil N2O emission rates in Korean pine plantations of all stand ages were not significantly different from those in larch plantations. The main factors driving the CO2 emission rate were total soil carbon content and microbial biomass nitrogen in Korean pine and larch plantations. Microbial biomass nitrogen was affected by the tree species and stand age. The CH4 absorption rate was affected by microbial biomass carbon, dissolved organic carbon, and dissolved organic nitrogen contents. Microbial biomass carbon  was regulated by tree species and stand age. The emission rate of N2O was affected by the contents of dissolved organic nitrogen, ammonium and nitrate. Dissolved organic nitrogen content was affected by stand age. In conclusion, different soil physical and chemical properties and microbial biomass carbon and nitrogen  can explain the variation in soil greenhouse gas emission rates among forests with different tree species and stand ages.
    Effects of freeze-thaw process on the emission of two greenhouse gases from different forest soils in Changbai Mountain.
    XIN Gui-min, ZHAO Qing-zhu, YIN Hang,  LI Long, HE Shu-min, ZHOU Pei-hua, FU Min-jie
    2021, 40(3):  644-653.  doi:10.13292/j.1000-4890.202103.003
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    We examined the emission of CO2 and N2O from soils of five forest types (hardwood broad-leaved forest, Korean pine broad-leaved forest, secondary birch forest, Changbai pine forest and Mongolian oak forest) in the process of freeze-thaw by in situ continuous sampling. The results showed that soils from all the forest types were CO2 and N2O source during freeze-thaw season. The average flux of CO2 and N2O for secondary birch forest and Korean pine broad-leaved forest soils were significantly higher than that of other forest types. Except for the hardwood broad-leaved forest, there was a significant negative correlation between CO2 flux and soil water content in the forest soils. The water sensitivity of soil CO2 emissions varied greatly among different forest types. There was a significant positive correlation between soil N2O flux and soil water content in all forest types except the hardwood broad-leaved forest. The soil CO2 and N2O emission fluxes in five forest types were related to the temperature of surface soils by quadratic function.
    Effects of management patterns on soil physicochemical properties and ecological stoichiometric ratio in Pinus massoniana near mature forest.
    LU Li-hua, LI Hua, CHEN Lin, MING An-gang, YANG Yu-jing
    2021, 40(3):  654-663.  doi:: 10.13292/j.1000-4890.202103.020
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    In a 25-year-old Pinus massonianaplantation, five forest management patterns were set up to examine the effects of forest management pattern on soil physicochemical properties and ecological stoichiometric ratio. The management patterns included: (1) super-large diameter timber cultivation (PTD), (2) continuously planting P. massoniana after clear-cutting (PM), (3) planting Castanopsis hystrix after clear-cutting (CH), (4) planting P. massoniana×C. hystrix same aged mixed forest after clear-cutting (PCT), and (5) planting P. massoniana×C. hystrix differentaged mixed forest after thinning (PCY). Results showed that forest management pattern significantly affected soil C∶N and N∶P and soil physicochemical characteristics except for soil bulk density and total potassium. Soil total porosity in CH and PCT was significantly higher than that in PTD and PCY. Soil pH was the highest in CH. The contents of soil total carbon, total nitrogen, available nitrogen, and total phosphorus were higher in PCY and PTD than in other forest management patterns, whereas the content of soil available phosphorus in CH and PCT and available potassium in PCT were higher than in other patterns. Soil C∶N was higher in PM and PCT, whereas soil N∶P in PCY was slightly higher than in PTD and CH but significantly higher than in PM and PCT. There was no significant difference of C∶P among different patterns. Our results indicated that soil quality of C. hystrix pure forest and P. massoniana×C. hystrix differentaged mixed forest was slightly higher than that of the patterns of super-large diameter timber cultivation and P. massoniana×C. hystrix sameaged mixed forest, but significantly higher than that of continuously plantingP. massoniana. We should pay attention to the limitation of soil phosphorus availability on plant growth resulted from the extended rotation periods of P. massoniana stands.
    Effects of shading on the growth indices and stoichiometric characteristics of Firmiana platanifolia seedlings.
    ZHI Xi-min, WANG Meng-ying, NIU Pan-qing, YANG Yao, JIANG Meng-lin, HU Yun-yi, CHEN Liang-hua, GAO Shun
    2021, 40(3):  664-671.  doi:10.13292/j.1000-4890.202103.023
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    The content and stoichiometry of nutrients in plant tissue reflect the distribution and interaction of elements in plants, as well as plant nutrient use efficiency and the nutrient limitation of the environment. Here, we analyzed the effects of four light intensities (full light, 50%, 75% and 95% shading) on the growth and the contents and stoichiometric characteristics of C, N, P, and K in Firmianaplatanifolia seedlings. Results showed that shading significantly affected growth traits, biomass, element content and accumulation, and stoichiometric ratio of seedlings (P<0.05). The height and specific leaf area of seedlings increased with the increases of shading intensity, while the basal diameter and roughness decreased. The total biomass was the highest under 75% shade and the lowest under 95% shade. Across those shading treatments, foliar C, N, P and K concentrations were higher than that in roots and stems. The N content in different organs followed the order of leaf>root>stem, while K content was in order of leaf>stem>root. The total accumulation of C, P and K increased with the increases of shading intensity, with the maximum and minimum values occurring under 75% shade and 95% shade, respectively. The changes of C∶N and C∶P of seedlings were similar, which increased first and then decreased with the increases of shading intensity, and reached the maximum value under 50% shading. N∶P in each organ was much lower than 14, indicating that seedling growth under different shading conditions was severely restricted by nitrogen availability. Our results highlight that shading can regulate the nutrient accumulation and distribution of F.platanifolia seedlings under different light environments, with consequences on biomass production. The 75% shading is optimal for seedling breeding, which helps to increase the height, specific leaf area, biomass, nutrient content and accumulation. Excessive shading might inhibit seedling growth.
    Soil nutrients and their ecological stoichiometry of Pinus yunnanensis forest along an elevation gradient.
    2021, 40(3):  672-679.  doi:10.13292/j.1000-4890.202103.006
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    I compared the differences in the contents and stoichiometry of soil organic carbon (C), total nitrogen (N), total phosphorus (P), total potassium (K), available nitrogen (AN), available phosphorus (AP), and available potassium (AK) in Pinus yunnanensis secondary forest along an elevation gradient in northeast Yunnan. Results showed that (1) the concentrations of C, N, P, K, AN, AP, AK among elevations ranged 7.85-31.61 g·kg-1, 1.08-2.11 g·kg-1, 0.19-1.41 g·kg-1, 3.65-15.10 g·kg-1, 51.33-144.35 mg·kg-1, 0.56-2.42 mg·kg-1, 0.03-0.35 g·kg-1, respectively; (2) with increases in elevation, soil C, N, P,P∶K, C∶N showed a trend of first increasing and then decreasing, whereas C∶P and N∶P showed an opposite trend; (3) Soil C content was positively correlated with N, AN, AP, AK,C∶N, C∶P, C∶K, N∶K or P∶K, but negatively correlated with K. These results suggest that the main soil nutrients and their stoichiometric characteristics of P. yunnanensis forest in this area varied obviously with altitude, with poor nitrogen and phosphorus status. Nutrient rich soil was found in the middle elevation, which is consistent with the growth performance of P. yunnanensis. Results from this study provide insights for understanding the growth and distribution of P. yunnanensis.
    The nutrient and ecological stoichiometric characteristics of soils developed from different parent rocks in areca plantation, Hainan Province.
    ZHAO Yue, LI Yu-zhu, SU Lei, GE Cheng-jun, YANG An-fu, TANG Shi-xin, BAO Xue-lian, XIE Hong-tu
    2021, 40(3):  680-691.  doi:10.13292/j.1000-4890.202103.033
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    Parent rock plays an important role in driving the nutrient content and characteristics of soils. In this study, we investigated the contents and stoichiometry of carbon, nitrogen, and phosphorus in areca plantation soil formed by different parent rocks, including volcanic, intrusive, metamorphic and sedimentary rock. The sampling sites are distributed in 11 cities and counties in Hainan Province. We examined the variations of soil nutrients among parent rocks and different soil layers. The results showed that soil nutrient status and stoichiometric characteristics of areca plantations were influenced by the factors related to the historical heritage of parent rocks. The contents of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and available nitrogen (AN) in soils developed from volcanic rocks were significantly higher than those in intrusive rocks, metamorphic rocks, and sedimentary rocks. The contents of total and available potassium (TK and AK) in soils developed from intrusive and sedimentary rocks were significantly higher than those in volcanic rocks and metamorphic rocks. The characteristics of the parent rocks affected the distribution of soil nutrients among soil profile. The contents of AN, AK, and DOC/AP in sedimentary rocks showed no differences among soil layers. The stoichiometric ratios of carbon, nitrogen and phosphorus showed the opposite variation between the soils developed from volcanic and sedimentary rocks, while that of carbon and phosphorus showed the same variation pattern. The higher SOC/TN and lower TN/TP in volcanic rocks indicated that the decomposition rate of organic carbon would be lower and that nitrogen availability was severely limited. The higher DOC/AN and lower AN/AP in sedimentary rocks indicated that the soil was richer in active organic carbon pool but poorer in available nitrogen, highlighting the limitation of N. In general, the contents of soil organic carbon, total nitrogen and available phosphorus were all at an optimal state, while the contents of total phosphorus (except for volcanic rock) and available potassium were mainly at a scarce state. To improve the soil nutrient content and its availability, and further mine the planting potential, the soils should be reasonably fertilized and scientifically managed according to different parent rocks.
    Stoichiometric characteristics of fine roots in Phyllostachys edulis and its varieties.
    GUO Wen, HUANG Hong-liang, WANG Rui, YANG Chang, LEI Gang, QI Liang-hua
    2021, 40(3):  692-700.  doi:10.13292/j.1000-4890.202103.015
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    The stoichiometric characteristics of fine roots in Phyllostachys edulis and its varieties (P. edulis f.luteosulcata, P. edulis f.taokiang, P. edulis f. pachyloen, P. edulis f.gracilis) at three stages (1, 3, and 5 years old) were analyzed and compared, aiming to explore nutrient use strategies of P. edulis and its varieties. The results showed that: (1) The stoichiometric characteristics of fine roots in P. edulis were varietyspecific, while age had minor effects. (2) There were differences of nutrient contents in fine roots of P. edulis and its varieties. The contents of total C, total N and total P in fine roots of P. edulis f.luteosulcata were higher than other varieties. The C∶N and C∶P of fine roots of P. edulis were larger, and no differences of fine root N∶P across P. edulis and its varieties were found. (3) Fine root N and P contents in P. edulis and P. edulis f.gracilis showed a significant allometric relationship, and the fine roots of P. edulis and its varieties were generally limited by P availability. The allometric relationships among C, N and P elements in fine roots of other bamboo species were not significant, indicating a similar nutrient allocation pattern. (4) Fine root stoichiometry and soil chemical properties were closely correlated, with the C∶P of fine roots being mainly restricted by soil organic matter and total P content. Compared with soil environmental factors, fine root stoichiometric characteristics of P. edulis and its varieties were more limited by the genetic characteristics of bamboo species. The stoichiometric characteristics of fine roots of P. edulis and its varieties were affected by their growth stage. The nutrient use strategies differed across bamboo species.
    Stoichiometric responses of Phragmites australis organs to soil factors in a wetland from arid area.
    ZHANG Jian, QI Xuan-xuan, LIU Dong, ZHAO Hai-yan, XIE Huan-jie, CAO Jian-jun
    2021, 40(3):  701-711.  doi:10.13292/j.1000-4890.202103.010
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    Understanding the response of plant element concentrations and stoichiometry to the changes of soil factors is essential to predict the responses of fragile and sensitive ecosystems to environmental changes. We examined the ecological stoichiometry of different organs in Phragmites australis and the driving factors in a wetland of Yangguan, Dunhuang. The results showed that carbon (C) and phosphorus (P) concentrations in different organs of P. australiswere in a descending order of leaf > root > stem, nitrogen (N) concentration and N∶P were in order of leaf > stem > root, C∶N was in order of root > stem > leaf, and C∶P was in order of stem > root > leaf. The concentration of C in leaves and roots was significantly higher than that in stems (P<0.05), but there was no difference between leaves and roots (P>0.05). The concentrations of N, P and C∶N, C∶P and N∶P varied among organs (P<0.05). Root N∶P of P. australis was <14, leaf N∶P was >16, and stem N∶P was between 14 and 16. The C concentrations of different organs were not significantly correlated (P>0.05). The N concentrations between root and stem and that between root and leaf showed a significantly positive correlation (P<0.01). The P concentrations between root and stem were positively correlated (P<0.01). There was a positive correlation between soil salinity and N concentration in roots and stems (P<0.01). The P concentrations in stems and leaves were significantly positively correlated (P<0.05). Soil P concentration was positively correlated with stem P concentration (P<0.01). Soil available P concentration was positively correlated with root and stem N concentration (P<0.05). Soil P was the main factor driving the stoichiometry of roots and stems of P. australis, while soil salinity was the main factor driving the stoichiometry of leaves. P. australis tended to adapt to the high salinity and low P conditions by increasing the N concentration in various organs.
    Seasonal variations of non-structural carbohydrate contents in coarse roots of Quercus variabilisBlume at different altitudes in the eastern Qinling Mountain.
    ZHANG Yi-ping, SHI Zhi-qiang, ZHU Lei, JIAO Hui-jing, WANG Chun-qiu, WU Jing, XU Jun-liang
    2021, 40(3):  712-720.  doi:10.13292/j.1000-4890.202103.017
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    Understanding the carbohydrate reserves in root is necessary for the accurate estimation of carbon allocation between aboveground and belowground organs. Here, we investigated the seasonal variations of non-structural carbohydrates (NSC) and its components (soluble sugar and starch) in coarse roots of Chinese cork oak (Quercus variabilisBlume) at two altitudes (650 and 970 m) in eastern Qinling Mountain. Root samples were collected for 14 times at a biweekly/monthly interval from May 2016 to June 2017. The results showed that the concentrations of NSC and its components in Q. variabilis coarse roots had a significant seasonal variation at both altitudes (P<0.05), except for the starch at high altitude. The maximum concentrations of NSC in coarse roots appeared at the non-growing season (February), and declined at the beginning of the growing season (March). Starch was the major contributor to total NSC in oak coarse roots, accounting for 61% and 71% of the total NSC at high and low altitudes, respectively. As the reservoirs for future use, higher content of starch in coarse roots would support carbon resource and guarantee tree growth in the next year. There was a significant difference in the NSC concentrations of Q. variabilis coarse roots between high and low altitudes (March, P<0.05). Overall, the NSC concentration of Q. variabilis was lower at high altitude (10.26%) than that of the low altitude (13.96%). Seasonal fluctuations of NSC in coarse roots of Q. variabilis were consistent with the tree’s phenological rhythms. The storage of NSC in coarse roots at the end of the growing season and the non-growing season is important for the onset of tree growth in the following year. Our results help understand the mechanism of carbon supply from underground organs to tree growth.
    Population structure of Cerasus serrulata in Baxianshan National Nature Reserve.
    QIU Zhen-lu, LI Xue-ying, TANG Li-li, ZHANG Mei, YANG Li-fang, SHI Fu-chen
    2021, 40(3):  721-730.  doi:10.13292/j.1000-4890.202103.021
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    Cerasus serrulata is a wild species of cherry blossoms, with beautiful flower color and tree shape. It is an important and rare ornamental plant resource ofCerasus. A relatively concentrated population of wild Cerasus serrulata was recently found in the northern mountainous area of Tianjin, which is located at the east of Yanshan Mountains. To clarify the population characteristics of wild Cerasus serrulata and explore its ecological habits, we carried out community investigation at three different slope positions (shady slope, ridge, and sunny slope) in Baxianshan Mountain National Nature Reserve of Tianjin. We examined the population structure and the change of species diversity of Cerasus serrulata community with altitude and slope position. Principal component analysis and redundancy analysis were used to explain the differences among communities and the influence of community structure on diversity. The results showed that: (1) Cerasus serrulata was a companion species in the deciduous broadleaved forest. The main species of tree layer in the community were Quercus mongolica, Fraxinus chinensis,Quercus aliena,Carpinus turczaninowii,Euodia daniell, Morus alba and Acer truncatum, while the main species of shrub layer were Rhododendron mucronulatum,Spiraea trilobata, Deutzia parviflora, Deutzia grandiflora, Celtis koraiensis andWeigela florid. The population structure and community structure of Cerasus serrulata varied across slope positions. (2) The age structure of Cerasus serrulata population showed an inverted “J” type. The regeneration status was the best in the altitude of 600-800 m and at the sunny slope. (3) Under different slope positions, the Shannon niche breadth of Cerasus serrulata population followed the order of sunny slope > ridge > shady slope. The species with the highest niche overlap with Cerasus serrulata were Salix sinicaand Quercus mongolica in shady slope, Euodia deniellii and Quercus mongolica in ridge, and Armeniaca vulgarisand Morus alba in sunny slope. (4) The diameter class distribution of tree layer showed an inverted “J” pattern. The diversity index increased first and then decreased with the increases of altitude. In different slope positions, the diversity index was the highest in shade slope and lower in the ridge and sunny slope. The diversity index of shrub layer was opposite to that of tree layer. The species diversity of the community increased with the development of the community, with the dominance of the dominant species being further increased. The companion species Cerasus serrulata population may decline in the shady slope and develop well in the ridge and sunny slope. Our results can provide a scientific basis for the protection and utilization of wild Cerasus serrulatepopulation in northern China.
    Numerical classification and ordination of shrub communities on the north slope of Qilian Mountains.
    ZHAO Ting-ting, ZHAO Cheng-zhang, KANG Man-ping, LI Qun, TANG Yu-rui, ZENG Hong-xia, WANG Yu-fang
    2021, 40(3):  731-739.  doi:10.13292/j.1000-4890.202103.013
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    The spatial distribution pattern of plant communities is a consequence of interspecific interaction in heterogeneous habitats. The study on its differentiation and its relationship with environmental factors is helpful to understand plant adaptation. Based on the survey data from 28 plots on the north slope of Qilian Mountains, the TWINSPAN and CCA analysis methods were used to explore the relationship between spatial distribution of shrub communities and environmental factors. The results showed that: (1) shrub communities on the north slope of Qilian Mountains could be classified into seven association groups by TWINSPAN, namely, Ass. Kalidium foliatum+Phyllanthus urinaria, Ass.Ajania fruticulosa+Sympegma regelii, Ass. Sympegma regelii+Artemisia capillaries, Ass.Lyonia ovalifolia+Allium polyrhizum, Ass.Caragana opulens+Stipa capillata, Ass. Caragana jubata+Salixcupularis, and Ass.Dosiphora fruticose+Polygonum viviparumn. (2) The results of CCA ordination showed that altitude and soil salinity were the main environmental factors driving the distribution of shrub communities on the north slope of Qilian Mountains, while soil organic matter, soil water content, soil bulk density and soil pH were the secondary factors. Soil available phosphorus and available potassium had minor effects on the distribution of plant community.

     

    Podding characteristics of Caragana aurantiaca shrub ramet in riparian zone of Tekes River, Yili.
    HAN Da-yong, HU Peng-fei, ZHANG Wei, CHAI Yong-bin, NIU Zhong-ze, HE Qi, AERMANAI·Kadeerbieke, NIU Yi-fei, PENG Na-na, SUERNA·Jinbao, YANG Yun-fei
    2021, 40(3):  740-748.  doi:10.13292/j.1000-4890.202103.022
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    By surveying Caragana aurantiaca population in the riparian terrace and floodplain of Tekes River in Yili, we explored the relationships of number, weight and size of pods with vegetative ramet height, branch number and shrub diameter, and examined the roles of pod production in population regeneration. The results showed that the abundance, length, and biomass of C. aurantiacapods in the terrace were significantly higher than those in the floodplain, whereas both the sexual reproductive allocation and single pod weight were significantly lower than those in the floodplain. The distribution characteristics of the number and biomass of pod were consistent and the values were 0-20 and 0-0.5 g respectively, which showed Lshaped distribution patterns and complied with the gamma distribution. The weight of individual pod varied from 10-30 mg, showing a lognormal distribution. The large individuals largely contributed to the variations of pod sizes in both habitats. The results of standard major axis regression analysis showed that the regression between the pod biomass and ramet heights in floodplain habitat was not significant, whereas the regression between the pod numbers, pod biomass and ramet heights, branch numbers and shrub diameters were statistically significant. Irrelevant of the pod amount or pod biomass, their slopes in the two habitats showed an order of ramet height > shrub diameter > branch number. The slopes of ramet heights and shrub diameters were statistically insignificant, but were larger than that of branch numbers. Both habitats can grow a large number of pods. The terraces tended to produce the small pods with large amount, while the floodplain tended to produce large pods with small amount. The population regeneration processes were not constrained by seed source. We propose that conservation strategies should emphasize on the increases of height, diameter, and pods, which would help accelerate the self-regeneration and self-maintenance of this shrub species.
    Effects of soil and topographic factors on functional traits of dominant plant species in a grassland of loess hilly region, Northwest Shanxi.
    JI Wen-xia, ZHAO Feng-xia, ZHANG Rui, TANG Xue-juan, YAN Li-fei, ZHANG Jin-tao
    2021, 40(3):  749-758.  doi:10.13292/j.1000-4890.202103.016
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    It is essential to predict the impacts of climate change on ecosystem functioning. The effects of environmental factors on the functional traits of the dominant plant species are becoming more obvious with the increasing warming and drying in the Loess Plateau. In this study, using the redundancy analysis, we examined the effects of soil and topographic factors on the functional traits of nine plant species in a grassland in the loess hilly region of Northwest Shanxi. Our results showed that soil and topographic factors played a key role in affecting the functional traits of dominant species, but did not affect that of nondominant species. Soil water content and available phosphorus content were the key soil factors affecting the functional traits of the dominant species. Soil water content was positively correlated with the height of the dominant species but negatively correlated with the relative branch number. Soil available phosphorus content was positively correlated with leaf nitrogen content, dry weight per plant and specific leaf area of dominant species, but negatively correlated with leaf carbon/nitrogen ratio and leaf dry matter content. Altitude is the main topographical factor affecting the functional traits of dominant species. It was positively correlated with leaf dry matter content and relative branch number of dominant species, and negatively correlated with plant height, leaf carbon content, and leaf area. Our results suggest that plant species in loess hilly areas would change resource use strategies to adapt to the environment of reduced soil moisture and nutrients under future warming and drying climate.
    Responses of belowground bud bank to simulated extreme drought in the meadow steppe of Inner Mongolia.
    Teniwu, GUO Zi-yue, LIU Dan, LUO Wen-tao, Wuyunna, Aruhan, QIAN Jian-qiang
    2021, 40(3):  759-765.  doi:10.13292/j.1000-4890.202103.005
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    The extreme climatic events caused by global changes have significant impacts on ecosystem structure and function of grasslands. As the important propagule bank in perennial grasslands, the responses of belowground bud bank to extreme drought in semiarid meadow steppe have not been clarified. In this study, using a simulated extreme drought experimental platform, we explored the responses of belowground bud bank, aboveground vegetation, and their relationships to simulated extreme drought during growing season in the Hulunbeir meadow steppe of Inner Mongolia. Results showed that under ambient precipitation and drought treatments, the total bud densities were 1443 and 1128 buds·m-2, the total shoot densities were 1791 and 1346 shoots·m-2, and the meristem limitation index were 0.84 and 0.83, respectively. The simulated extreme drought treatment had no significant effect on the belowground bud bank density, aboveground shoot density and their relationships at the community scale. For the dominant plant group, rhizomatous grasses, the extreme drought treatment did not affect their belowground bud banks. Our results demonstrated the resistance of belowground bud bank to extreme drought in semiarid meadow steppe. Belowground bud bank could be an insurance strategy of meadow steppe, and could facilitate plant regeneration and vegetation restoration under extreme climate, which is essential to vegetation stability and ecosystem function maintenance.
    Effects of arbuscular mycorrhizal fungi on biomass distribution and root architecture characters ofZenia insignis seedlings in karst soil.
    QU Ming-hua, YU Yuan-chun, WANG Jia, XUE Liang, WANG Zu-fang, LI Sheng
    2021, 40(3):  766-776.  doi:10.13292/j.1000-4890.202103.002
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    Vegetation recovery in karst region is limited by poor availability of soil nutrients. Root plays an important role in the growth and development of seedlings. Arbuscular mycorrhizal fungi (AMF) can promote dry matter accumulation and stress resistance of karst plants, whereas the mechanism and effect of AMF infection on roots of main restoration tree species in karst area remain largely unknown. In this study, the effects of AMF on growth, root architecture of Zenia insignis in karst soil with different nutrient levels were evaluated in a greenhouse experiment. There were four inoculations of arbuscular mycorrhizal fungi: Funneliformis mosseae (Fm), Rhizophagus intraradices (Ri), their mixture inoculation (Mi) and no inoculation (CK), and two nutrient levels. Under lownutrient level, Fm treatment significantly increased root architecture parameters. The inoculated plants had the maximum colonization rate, and aboveground biomass, root biomass, total biomass, the numbers of tips, forks and crossings and projected area were increased by 2.50, 5.60, 3.67, 3.03, 3.78, 3.66 and 3.56 times than CK, respectively. Ri treatment did not affect aboveground biomass, root biomass, total biomass and the number of forks, but decreased the numbers of tips and crossings and projected area by 46.59%, 50.00%, and 38.60%, respectively. Mi treatment increased aboveground biomass, root biomass, total biomass, the numbers of forks and crossings and projected area by 3.02, 3.47, 3.14, 1.64, 1.60 and 1.70 times, respectively, but did not affect the number of tips. Under highernutrient level, Fm treatment increased root biomass and projected area by 2.38 and 1.51 times respectively, did not affect aboveground biomass, total biomass, the numbers of forks and crossings, but decreased the number of tips by 22.82%. Ri treatment increased root biomass, total biomass, the numbers of tips and crossings and projected area by 2.29, 1.37, 1.31, 1.29 and 1.66 times, but did not affect aboveground biomass and the number of forks. Mi treatment increased aboveground biomass, total biomass, the number of tips and projected area by 1.44, 1.46, 1.25 and 1.40 times, but did not affect root biomass, the numbers of forks and crossings. Collectively, inoculation with F. mosseae significantly increased root architecture parameters and plant growth under low-nutrient soil.R. intraradices had a positive impact in soils with low calcium and high phosphorus contents. F. mosseae has extensive ecological adaptability and facilitates resource uptake of roots and root spatial expansion in soils, showing high application potential for vegetation restoration under low-nutrient karst soil.
    Bird diversity in Dongpu Reservoir.  
    YU Qing-qing, SUN Qing-ye
    2021, 40(3):  777-787.  doi:10.13292/j.1000-4890.202103.018
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    The stopover wetlands play an important ecological role in the migration of waterbirds, which supply energy and rest site for waterbirds. The largescale loss and degradation of wetland habitats seriously affect the migration of waterbirds. Under such context, the ecological substitute role of small and medium sized wetlands with good habitats has gradually emerged. Therefore, studies on bird resources in small and mediumsized wetlands are not only important for monitoring bird resources but also for the scientific protection of wetland networks of migratory birds. From November 2017 to December 2019, we used point sampling method and line sampling method to investigate species richness, abundance, and habitat of waterbirds in Dongpu Reservoir. A total of 118 bird species in 16 orders and 43 families were recorded. Among them, there were 2 and 10 species among China’s National Class Ⅰ and Ⅱ Key Protected Birds, including Ciconia boyciana andGrus monacha. There were 16 dominant species, including Mareca falcata, Phalacrocorax carbo, Anas zonorhyncha, Podiceps cristatus, Egretta garzetta, and Tachybaptus ruficollis. The Shannon diversity and Pielou evenness of birds in the study area were summer > autumn > winter > spring, while the Simpson dominance showed an opposite pattern. Our results showed that the role of Dongpu Reservoir as a stopover for overwintering waterbirds is expanding.
    Behavioral responses of Crested Ibis (Nipponia nippon) to low temperature in winter.
    2021, 40(3):  788-794.  doi:10.13292/j.1000-4890.202103.019
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    Low temperature affects the growth, metabolism, and living status of birds. Birds can change their behavior to adapt to changing temperature. Crested Ibis (Nipponia nippon) is an endangered species endemic to East Asia, which was introduced to Beidaihe of Hebei Province from Yangxian of Shaanxi Province to establish the world’s highest-latitude acclimation population. In this study, we analyzed the effects of season and temperature on the rest behavior of Crested Ibis in Beidaihe and Yangxian. The doublelegstand with bill out (DO) was the most common rest behavior in wandering period (70.9%). However, the proportion of DO decreased significantly in wintering period (55.6%), while the proportion of onelegstand with bill out (OO) and bill tuck increased correspondingly. Temperature significantly affected the behavior of double leg stand with bill tuck (DT), OO and onelegstand with bill tuck (OT). Therefore, CrestedIbis adapted to low temperature by increasing the proportion of protecting exposed parts in winter. In winter, the proportion of groveling on branch of nocturnal roost tree increased with decreasing temperature, but this behavior was not observed in daytime. This suggested that groveling might be a response of Crested Ibis to the extremely tolerable low-temperature, which should arouse vigiance in protection monitoring. Crested Ibis seldom used the shelters in the acclimation cage in winter, indicating they could adapt to temperature as low as -20 ℃. To ensure the safe wintering of Crested Ibis, we suggest that more evergreen trees such as Pinaceae are needed to provide optimalnocturnal roost habitat, and that using wind barrier using straws to reduce the negative effect of strong wind at night in the acclimation cage.
    Physiological responses and Cd accumulation characteristics in four cold-resistant flower species exposed to Cd polluted soil.
    ZHANG Ming-hua, ZHANG Chang-feng, WANG Hui-hui, XIONG Rui, PU Yu-lin, ZHANG Shi-rong, XU Xiao-xun, JIA Yong-xia
    2021, 40(3):  795-803.  doi:10.13292/j.1000-4890.202103.008
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    A pot experiment was conducted to investigate the physiological responses and accumulation characteristics to cadmium (Cd) of Dendranthema morifolium, Lupinus luteus, Primula vulgaris andPapaver rhoeas. The aims of this study were to explore the feasibility of phytoremediation technology using these four ornamental flowers in winter and spring, and to provide reference for improving the efficiency of phytoremediation technology. The results showed that: (1) There was no difference in the biomass of L. luteusbetween Cd treatments and the control. The root biomass of P. vulgariswas significantly lower at 80 mg·kg-1 Cd treatment than that of the control, being 74.51% of the control. The total biomass of D. morifolium and P. rhoeas was significantly lower than that of the control when the Cd concentration was higher than 10 and 40 mg·kg-1, respectively, with the minimum value at 80 mg·kg-1 Cd treatment, which were 41.21% and 64.15% of the control, respectively. (2) Under Cd treatments, the activities of antioxidant enzymes inL. luteus were significantly higher than those in the control, the content of MDA was not changed, and the ability of scavenging ROS was the strongest and unharmed. The activity of antioxidant enzymes in P. vulgaris increased slightly, the content of MDA and REC increased slightly, and the ability of scavenging ROS was better. The capacity of scavenging ROS of D. morifolium and P. rhoeas was the lowest, which were suffered serious oxidative damage. (3) Under all Cd treatments, the allocation of Cd was higher in shoot than in root, the BCF and TF were greater than 1, and the maximum concentration and content of Cd in shoot were 136.20 mg·kg-1 and 1118.20 μg·plant-1, respectively. TF in L. luteus, P. vulgaris and P. rhoeas was less than 1, Cd concentration and accumulation of shoot, BCF and TF were L. luteus > P. vulgaris and P. rhoeas. In summary, compared with P. vulgaris and P. rhoeas, D. morifolium has relatively poor tolerance to Cd, but it has strong absorption and transfer ability to Cd, which is suitable for the remediation of Cd polluted soil in winter and spring. L. luteus has strong tolerance, absorption and transfer ability to Cd, which is also suitable for the remediation of Cd polluted soils in winter and spring.
    Assessment of heavy metal pollution in dust of residential quarters and streets in Shenyang.  
    LI Ping-ping, MIAO Chun-ping, CHEN Wei, YU Shuai, HU Yuan-man, HE Xing-yuan
    2021, 40(3):  804-812.  doi:10.13292/j.1000-4890.202103.001
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    Urban residential area is an important place for human activities and is closely related to the daily life of residents. To understand the spatial distribution of heavy metals in the dust of residential districts and streets in Shenyang, we analyzed heavy metal concentrations, and assessed the pollution degree using enrichment factors and geoaccumulation indices by collecting dust samples in residential districts and streets. The results showed that the average concentrations of Cr, Cd, Cu, Pb and Zn in the dusts exceed the background value of surface soil elements in Liaoning Province. The concentrations of heavy metals Cu, Fe, Mn and Zn in the dust of streets and that of Cd, Cr, Fe, Mn and Pb in residential districts showed significant spatial variations. Among all the investigated heavy metals, Cd, Zn, and Pb were the most serious pollutants. The Cd and Zn concentrations in the residential districts were significantly higher than those in the streets. The pollution levels of heavy metals in the residential areas of Shenyang ranged from light to moderate degrees.
    Spatiotemporal variations of PM2.5 and driving factors over central and eastern China between 2015 and 2019.
    YAO Rong-peng, ZHANG Bo, WANG Li-bing, ZHANG Yao-wen
    2021, 40(3):  813-824.  doi:10.13292/j.1000-4890.202103.004
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    Smog events are widespread in central and eastern China. Scientifically identifying the spatiotemporal variations and the drivers of PM2.5, the primary cause of smog, is of great significance for regional prevention and control. Using PM2.5 data from December 2014 to November 2019 of the national air quality monitoring stations, the spatiotemporal characteristics and variations of PM2.5 pollution were analyzed by using the methods of geostatistics, REOF and Geodetector. The region classifications were identified, and the driving factors for differentiation of PM2.5 were identified in each region. The results showed a steady downward trend in mean annual PM2.5 concentration in central and eastern China, with a mean annual decrease of 3.2 μg·m-3. The area with high annual PM2.5 concentration showed a rapid spatial contraction. There was an insignificant increasing tendency of PM2.5 pollution days in some areas. The concentration of PM2.5 decreased outwardly in the center of BeijingTianjinHebei, with a characteristic of “higher concentration in the north than in the south”. The strong spatial agglomeration of PM2.5 concentration was distributed in central and eastern China. The values of global Moran’s I in all four seasons exceeded 0.70 (P<0.01). Hot spots were mostly distributed in and around the North China Plain, while cold spots were distributed in south China. Based on the result of REOF, three regions were classified. Their boundaries roughly overlapped with the topography and geomorphology. The time coefficients showed a “pulse” downward trend, indicating a significant improvement trend of PM2.5 pollution. Meteorological factors and human activities are essential drivers for the differentiation of PM2.5 in different regions, with the key drivers being region-specific.
    Spatiotemporal variation of net primary productivity and its climatic driving factors in Xilingol League.
    WANG Shuang, LI Qing-xu, ZHANG Biao
    2021, 40(3):  825-834.  doi:10.13292/j.1000-4890.202103.028
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    Net primary productivity (NPP) is widely used in evaluating the quality and function of ecosystems. Monitoring the temporal and spatial variations of NPP in ecological engineering region is an important task of ecological construction effectiveness evaluation. Here, we evaluated the spatialtemporal variations of NPP in Xilingol League using sequential remote sensing data from 2000 to 2015 and CarnegieAmes Stanford approach (CASA), and analyzed the impacts of temperature and precipitation on NPP. The results showed that the NPP of Xilingol League ranged from 108.66 to 359.74 g C·m-2·a-1 during 2000-2015, with an average growth rate of 13.47 g C·m-2·a-1. The average NPP in Xilingol League was 254.18 g C·m-2·a-1 from 2000 to 2015, with a spatially descending trend from east to west. The NPP in Taipusi Banner, Duolun County, Xiwuzhumuqin Banner and Dongwuzhumuqin Banner was above 280 g C·m-2·a-1, the total areas of these regions covered 40.13% of Xilingol League. Approximately 94.56% of total area in Xilingol League showed an increasing tendency in NPP between 2000 and 2015, while the increased magnitude of NPP in 33.95% of area was more than 120 g C·m-2. The NPP in Xilingol League was positively correlated with rainfall, while 31.18% of area showed a positive correlation between NPP and temperature. The complex correlation coefficient between NPP and annual temperature and precipitation reached 0.59. We conclude that the NPP in about 55% of area is clearly driven by climatic factors. These regions should fully utilize the positive effects of climate change on ecological restoration. More ecological engineering measures should be adopted in the rest areas where the NPP is relatively insensitive to climate change.
    Analysis on ecological water demand and supply of Kaidu River based on water system connection.
    JI Chang-ming, CAO Cheng-lin, WANG Yi
    2021, 40(3):  835-843.  doi:10.13292/j.1000-4890.202103.026
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    Kaidu River is the source of Bosten Lake, the largest inland fresh water lake in China. The regulation of water resources in Kaidu River plays a key role in the production, living, and ecology of the Yanqi Basin and also in the watersystem connection between Bosten Lake and other water body in the basin. Ensuring the ecological basic flow and stable ecological function in Kaidu River is important for the effective management of water resources in the basin. We first improved Tennant Method by dividing the runoff data into different periods and improving the corresponding base flow standard. With the observed runoff data from Dashankou hydrological station in 1971-2016, we analyzed the ecological base flow and corresponding minimum ecological water demand of different periods at high and low flow period. The results showed that the minimum ecological water demand of Kaidu River in each year could be basically satisfied under the conditions of considering river water loss and the government’s surface water usage controlling rules of “Three Red Lines”. However, in the semidry and extremely dry years, the remaining water in the river is little, and thus the situation to guarantee the basic ecological water demand of the river would be severe. After ensuring the minimum ecological water demand, river water loss and surface water consumption, the surplus water of Kaidu River could serve for the ecological water demand of Bosten Lake and its watersystem connection in both wet and normal years. However, it could not satisfy the ecological water supply to Bosten Lake in the semidry and extremely dry years. Our results provide important guidance for maintaining ecological health and sustainable utilization of water resources in Kaidu River Basin.
    Responses of plant phenology to urban heat island effects in Beijing.
    MENG Dan, LIU Xin-rui, ZHANG Cong-cong
    2021, 40(3):  844-854.  doi:10.13292/j.1000-4890.202103.029
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    The rapid development of cities increases urban heat island (UHI) effect. Urban greening can alleviate the heat island effect, but plant phenology could be affected by the heat island effect. Using remote sensing images, we compared the plant phenology between UHI areas and non-UHI areas as well as the different levels of UHI intensity in Beijing. Landsat-8 images for Beijing were used to invert the land surface temperature (LST). Spatial analysis methods were used to identify UHI zones and the UHI intensity classification. With data of normalized differential vegetation index (NDVI) of MOD13A1, three phenological parameters (start of growth season (SOG), end of growth season (EOG), and length of growth season (LOG)) were extracted by the Dallimer mean value method and dynamic threshold method. The three parameters were used to examine the differences in plant phenology between the UHI areas and the non-UHI areas and between different UHI intensity levels. The UHI effect of Beijing in summer was more obvious than that in winter. The SOG in the UHI areas extracted by Dallimer mean value method was four days earlier, the EOG was nine days later, and the LOG was 13 days longer than that in non-UHI areas. The SOG in UHI areas extracted by dynamic threshold method was 10 days earlier, the EOG was four days later, and the LOG was 14 days longer than that in nonUHI areas. Compared with the Dallimer mean value method, the phenology calculated by the dynamic threshold method was closer to the observation data. Under higher UHI intensity, the SOG would be earlier, the EOG would be later, and the LOG would be longer. This study enriches the response mechanism of plant phenology to the UHI effect in North China, which helps us to understand the effects of global warming on ecosystems.
    Cooling effect of mountain greenspace on urban heat island in Karst mountain city: A case study of Anshun City.
    WU Wu, WANG Zhi-jie
    2021, 40(3):  855-863.  doi:10.13292/j.1000-4890.202103.032
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    Mountain greenspace is a typical type of urban green land landscape in Karst mountain cities, which plays a significant role in improving the urban ecological environment and promoting urban ecological service in Karst mountain cities. We analyzed the relationship between mountain greenspace and the distribution of cold points of urban heat island effect in Anshun City, a typical Karst mountain city in central Guizhou Province. We used cold/hot spot analysis and the thermal infrared remote sensing images and urban landscape structure spatial data in 2011 and 2016, based on the inversion analysis of urban heat island effect and the spatial temporal distribution characteristics of its intensity. We further revealed the cooling effect of mountain greenspace on urban heat island. The results showed that the average retrieved land surface temperature in Xixiu District of Anshun City increased by about 4 ℃ from 2011 to 2016, based on the results of Landsat thermal infrared remote sensing data inversion of surface temperature. The heat island effect in the main urban area showed an increasing trend, whereas the overall heat island area showed a decreasing trend. The green island area was mostly distributed in water and mountain greenspace. The mitigation effect of mountain greenspace on the heat island increased year by year. The cold/hot aggregation area showed an increasing trend. About 40%-50% of the cold accumulation area was contributed by mountain greenspace. The hot aggregation area was mainly composed of construction land and other land-use types. The mountain greenspace area was significantly negatively correlated with the surface temperature at the 500m grid scale, as indicated by the fact that surface temperature would decrease by 0.17-0.27 ℃ for every 10% increase in the proportion of mountain greenspace area in the grid. Our results provide a scientific basis for the mountain greenspace management, urban greenspace planning, and urban thermal environment mitigation in Karst mountain cities.
    Research advances in the relationship between root morphological structure, radial oxygen loss and salt/heavy metal uptake, accumulation and tolerance of wetland plants
    XIE Huan-huan, YE Zhi-hong
    2021, 40(3):  864-875.  doi:10.13292/j.1000-4890.202103.011
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    Many wetlands are currently faced with the problems of heavy metal pollution and salinization. It is important to use wetland plants to remediate these damaged wetlands, to increase the yield of sea rice, and to reduce the accumulation of toxic metals in rice grains. Wetland plants (including rice) develop various strategies and mechanisms to withstand environmental stresses. Their root system has high plasticity. The root morphology and anatomical structure can change with environmental conditions, which directly affect their adaptability to environmental stresses. In recent years, many studies examined root morphology, structure and oxygen secretion of wetland plants, and their relationships with the uptake, accumulation and tolerance of salts and heavy metals. Here, we reviewed the relationships between root morphology, apoplastic barrier, aerenchyma and oxygen secretion of wetland plants and their uptake, accumulation and tolerance to salts and heavy metals. We further prospected the future development of this field.
    Research progress and prospects on ecosystem services of global rice terrace.
    YANG Yan-fen, JIAO Yuan-mei, LIU Cheng-jing, DING Yin-ping, LIU Zhi-lin, XU Qiu-e
    2021, 40(3):  876-886.  doi:10.13292/j.1000-4890.202103.031
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    Rice terrace provides multiple ecosystem services. A global systematic review could improve the research and understanding of its ecosystem services. Based on the Millennium Ecosystem Service Classification System and systematic literature analysis, we summarized the research progress of global rice terrace ecosystem services. The literature on global rice terrace ecosystem services is mainly from China, Vietnam, and Philippines. Studies in China mainly use the value assessment method (VAM) while studies in foreign countries emphasize on physical assessment method (PAM) for assessing ecosystems services. The VAM results of Chinese rice terraces in four sites show higher regulating and supporting services than other ones. It is difficult to compare with each other due to different spatial units and calculating methods used in the studies. With respect to physical assessment, studies on regulating services were carried out on soil erosion, disaster, and pest regulations, studies on supporting services were carried out on the cycling and transformation of silicon that is beneficial to rice growth, and studies on provisioning services mainly focused on the impact factors for rice growth and its simulation prediction. At the landscape scale, increasing the number of patches planted with other crops beside rice could enhance all kinds of ecosystem services. The analysis framework based on ecosystem service matrix and mapping has promising application prospect. Future research should focus on the multiscale evaluation system of rice terrace ecosystem services, the tradeoff/synergy relationships from aspects of service formation mechanism, and the relationships among the pattern, process, service, and human well-being at landscape scale.
    Multi-scenario simulation of the impacts of land-use change on ecosystem service value on the Qinghai-Tibet Plateau.
    ZHANG Xiao-yao, LU Lin, YU Hu, ZHANG Xiao, LI Dong-hua
    2021, 40(3):  887-898.  doi:10.13292/j.1000-4890.202103.025
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    The Qinghai-Tibet Plateau has outstanding ecological service value. Due to the volatile climate and fragile environment on Qinghai-Tibet Plateau, it is vulnerable to interference from human activities. Based on the land-use data and an improved equivalent factor method, we quantitatively analyzed the impacts of land-use change on the spatial and temporal variations ofecosystem service values on the Qinghai-Tibet Plateau from 1992-2015. Furthermore, combined with the CA-Markov model, we explored the relationship between land use and ecosystem service value under the scenarios of natural development and ecological protection. From 1992 to 2015, the land-use structure of the Qinghai-Tibet Plateau was stable, with grasslands being the main land use type supplemented by woodlands and bare land. The overall value of ecosystem services showed an increasing trend. Grasslands, water body, and forests were the stable suppliers of ecological value of Qinghai-Tibet Plateau. The spatial distribution of the ecosystem service value of the Qinghai-Tibet Plateau was extremely uneven, while the distribution of different climatic zones was spatially heterogeneous. Cold spots were concentrated in the arid zone of the northwestern Qinghai-Tibet Plateau and the humid zone in the southeast. Hot spots were concentrated in the humid and semihumid zone in the middle. The altitude of 6000 m was the threshold of ecosystem service value of the QinghaiTibet Plateau. The land-use change under the ecological protection scenario is more balanced than that under the natural development scenario. Ecosystem service value generally increases, and the ecological environment develops optimally.
    Designing of precipitation index insurance of maize in Changwu, Shaanxi Province.
    YANG Xiao-juan, LIU Bu-chun, LIU Yuan, BAI Wei
    2021, 40(3):  899-907.  doi:10.13292/j.1000-4890.202103.027
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    Weather index insurance can be used to avoid the disadvantages of traditional agricultural insurance. Based on the data of yield and planting area of maize and meteorological data of Changwu in Shaanxi Province from 1990 to 2018, we analyzed the planting area, total yield, yield per unit area, trend yield, relative meteorological yield, water demand, and supply during growth period of maize. The maize planting risk was evaluated using the method of agricultural production loss-risk assessment. The pure rate of maize was determined by the Logistic modeling. The maize precipitation index during the whole growth period was designed according to the relationship between precipitation index and yield. The compensation scheme of maize precipitation index insurance was designed by projection pursuit regression. The results showed that planting area, total yield, yield per unit area, trend yield, and relative meteorological yield all showed an increasing trend over the years. The average water demand, supply, and deficit of maize were 650, 434, and 216 mm in the whole growing season, respectively. From late April to late August, water deficit of maize occurred. The largest water deficit was 33.65 mm in tasseling period in midJuly, and a slight water surplus was shown in September. The maize production was reduced by 14%, 20%, and 44% in 1994, 1995, and 1997, respectively, with the corresponding precipitation anomalies of -42.44%, -47.72% and -29.71% respectively. The planting risk probability of light, medium, severe and excessive disaster was 7.49%, 3.40%, 1.43%, and 1%, respectively. The pure rate of maize agricultural insurance was 2.92%. The cumulative ten-day precipitation during the growing season was designated as maize precipitation index, with a threshold value of 40 mm. The precipitation index was used to make compensation in sections. Our results provide a new choice for agricultural insurance of maize in Changwu, which is of great significance for solving the current dilemma of agricultural insurance.
    Parameter estimation and verification of the DSSAT-CROPGRO-Tomato model under the condition of different amounts of straw returned to the field in the greenhouse.
    LI Bo, SUN Xiang-long, YAO Ming-ze, BAO Hui, WANG Jun-hao
    2021, 40(3):  908-918.  doi:10.13292/j.1000-4890.202103.009
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    We examined whether the tomato growth simulation model DSSAT-CROPGRO-Tomato can accurately simulate the growth, development, and yield formation of tomatoes in northern China solar greenhouse under the condition of returning straw to the field. The model was verified based on the greenhouse tomato plot test data in both 2016 and 2018. There were four treatments of straw returning, including 0 (S0), 1.5×104 (S1), 3×104 (S2) and 4.5×104 kg·hm-2 (S3). The corresponding crop genetic parameters of different schemes were obtained using GLUE parameter estimation module. Moreover, the simulation accuracy of the model was verified by comparing the measured and simulated values of tomato phenology, fresh fruit yield, maximum leaf area index, soil moisture, soil inorganic nitrogen, and aboveground dry matter quality. The results showed that the coefficients of variation of the parameters PODUR (the duration of light 〖JP2〗and heat required for the final fruit load under optimal conditions) and SLAVR (specific leaf area)were 28.53% and 14.13%, respectively. The model had the highest simulation accuracy in 2016 when all treatments were under parameter estimation schemes, and its ARE (absolute relative error) and nRMSE were 10.33% and 7.12%, respectively. The model had high accuracy in simulating soil moisture, tomato growth, and yield. The results of leave-one-out cross-validation method showed that the overall error of the model to the yield of greenhouse tomato was 18.68%-21.95%. Our results indicated that the CROPGRO-Tomato model can accurately simulate tomato growth and yield formation in the solar greenhouse in Shenyang with straw returning to the field.
    Spatiotemporal variation and risk regionalization of frost damage of spring tea in Hangzhou City based on the phenological model.
    FAN Liao-sheng, JIN Zhi-feng, WANG Pei-juan, HUANG Hai-tao, YANG Jun, ZHU Lan-juan
    2021, 40(3):  919-928.  doi:10.13292/j.1000-4890.202103.034
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    Regionalization of frost damage risk on spring tea is helpful for optimizing the distribution of high-quality tea planting. Based on the phenology data of Longjing 43 spring tea in 2015-2020 and the meteorological daily data of Hangzhou National Reference Climatological Station in 1951-2020 and 263 regional automatic weather stations in 2010-2020, we estimated early germination date of spring tea in the missing years using an effective accumulated temperature phenology model, and analyzed the spatiotemporal variation of frost damage in spring tea production in Hangzhou City. The spatial distribution maps of frost damage risk for spring tea were developed by conducting the weighted average model of frost damage rate of spring tea. Results showed that the dates for early germination of spring tea and final frost were advanced during the past 70 years, with the advance of final frost date being faster than that of early germination date. The frost years of spring tea were decreasing due to decreasing years of mild frost, whereas severe frost years had a light increasing. The inter-annual variation of moderate frost damage was not obvious and fluctuated greatly among different decades. The variations of frost damage days at different grades were basically consistent with frost damage years. The occurrence frequency of mild, moderate, severe, and extra severe frost was 31.4%, 18.6%, 4.3% and 1.4%, respectively. There was no significant variation in the annual damage rate. For every 100m elevation rising, the early germination date of spring tea and the last frost date were delayed by about 1.3 and 2.6 days, respectively, and the frost damage rate of spring tea increased by about 1%. Generally, the risk of spring frost damage would be higher with increasing altitude. The frost damage on spring tea production showed regional variation in Hangzhou. The frost-free area of spring tea (its damage rate was less than 10%) accounted for 25.2% of the total area of Hangzhou, which was mainly distributed in the Qiandao lake region, the West Lake region, the Qiantang River valley and areas surrounded by large water bodies. Those regions were the priority areas for spring tea planting. The areas with the high risk of frost damage only accounted for 6.3% of total area of Hangzhou. Our results indicated that Hangzhou is suitable for planting high-quality and famous teas-because of the small frost damaging areas of spring tea and the light disaster level.