Table of Content

10 April 2017, Volume 36 Issue 4

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Response of Stipa breviflora height to grazing in a desert grassland.

WEI Zhi-jun1*, LIU Wen-ting1, LU Shi-jie2, Wang Tian-le1, ZHANG Shuang1, Ding Li-jun1

2017, 36(4):  885-891. 

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Plant height is a central part of plant ecological strategy. It is a potential way to analyze the regulation mechanism of plant population to herbivores. Based on a longterm grazing experiment in Sonid Right Banner, Xilingol, this study aimed to reveal the height response of desert grassland plant Stipa breviflora under grazing regulation through three different dimensions (i.e. leaf macroscopic traits, leaf anatomical traits, and leaf nutrient contents). The results showed that the plasticity index (PI) of S. breviflora leaf height was the largest and leaf length was the second. The leaf anatomical structure showed a higher PI of leaf thickness, and PIs of leaf traits were greater under heavy grazing than under moderate grazing. The PI of leaf phosphorus (P) content was greater than those of leaf nitrogen (N) and carbon (C) content. The PI of leaf N content was greater than that of C content. Leaf height of S. breviflora in the moderate grazing treatment was higher than in the nongrazing treatment, and nongrazing treatment had higher leaf height than heavy grazing treatment. The area of upper epidermis cell under heavy grazing was lower than those under the other treatments. The leaf N content was increased by grazing. Leaf height of S. breviflora was significantly positively correlated with leaf length, leaf width and leaf erection index, and negatively correlated with leaf rolling index. Furthermore, it was significantly positively correlated with upper epidermal cell surface area, upper epidermis cell thickness, and leaf C content.

Interspecific associations of dominant plant populations in a mid-subtropical Choerospondias axillaris forest.

PAN Gao1,2, ZHANG He-ping1*, PAN Deng1,2

2017, 36(4):  892-901. 

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A number of statistic methods (variance ratio method, χ² test, Pearson’s correlation coefficient test and Spearman’s rank correlation coefficient test) were used to characterize interspecific associations of 13 overstory tree species, 14 shrub species and 16 herbaceous species in a secondary natural forest of Choerospondias axillaris in mid-subtropical region at Qingyanghu National Forest Park, Hunan Province. The overall interspecific associations were non-significantly negative, significantly negative and non-significantly positive correlations among dominant plant populations in overstory, shrub and herbaceous layers, respectively. The χ² test showed that the speciespairs of negative correlation were dominant in the three layers, accounting for 80.77%, 80.22% and 83.33% of the total speciespairs in overstory, shrub and herbaceous layers, respectively; followed by speciespairs of positive correlation, which accounted for 16.67%, 18.68% and 16.67% in the three layers, respectively. There were few speciespairs of no correlations in the plant community. The Pearson’s correlation coefficient test showed that the number of speciespairs in positive association was 41, the number of speciespairs in negative association was 37, and the association ratio was 1.11 in overstory layer; the corresponding values were 34, 57 and 0.60, and 43, 77 and 0.56 in shrub and herbaceous layers, respectively. The Spearman’s rank correlation coefficient test showed that the number of species pairs in positive association was 40, the number of species pairs in negative association was 37, the number of species pairs in non-association was 1, and the association ratio was 1.08 in overstory layer; the corresponding values were 35, 55, 1 and 0.64, and 45, 74, 1 and 0.61 in shrub and herbaceous layers, respectively.

Nutrient absorption, accumulation, and distribution characteristics of three excellent native tree species plantations in karst area of western Hunan.

LI Jin-hua1, Li Zhi-hui1, LIU Qiu2*, WANG Pei-lan1, HU Shu-rong1

2017, 36(4):  902-909. 

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The content, accumulation, distribution and cycling dynamics of five nutrient elements (N, P, K, Ca, and Mg) in 31-year-old Corylus chinensis, Choerospondias axillaries and Tapiscia sinensis plantations in Xiangxi Autonomous Prefecture Forest Ecological Station were studied to clarify the nutrient use characteristics of different plantation ecosystems in karst area. The results showed that: (1) The contents of nutrient elements in tree organs, forest floor and litter were the lowest in the Ch. axillaries plantation among the three plantations. Maximum Ca and minimum P accumulations were found in tree organs, forest floor and litter in the three plantations, suggesting a typical characteristic of vegetation nutrient in karst region. The ranking order of nutrient element contents of different tree components in the three plantations was as follows: leaf > bark > branch > root > trunk. (2) Tree layer and forest floor layer had the biggest enrichment capacity of P in Ch. axillaries plantation. Tree layer and forest floor layer had the biggest enrichment capacity of P and Ca respectively both in C. chinensis and T. sinensis plantations. (3) The lowest and highest nutrient accumulation occurred in C. chinensis plantation and T. sinensis plantation respectively, and the latter was 188% of the former. Among the five nutrient elements, maximum Ca and minimum P accumulated in the three plantations, showing a similar pattern to the nutrient contents in the organs of the three species. (4) The ranking order of nutrient uptake, remaining and return amount in the three plantations was as follows: T. sinensis > Ch. axillaries > C. chinensis. The three plantations had a similar pattern of nutrient cycle rate, being the highest with K and the lowest with P; they also had a similar pattern of nutrient use efficiency, being the highest with P. (5) T. sinensis plantation was the optimal choice among the three tree species in karst area for its advantages of high absorption capacity, high remaining, low cycling rate and highly economical nutrient use. (6) A similar pattern of low content in organs, high enrichment from soil, low cycling rate and high use efficiency of P occurred in the three plantations. Therefore, P deficiency generally existed in soil of our tested region, which should be improved to guarantee the normal growth of forest plantations.

Canopy seed bank of Sophora alopecuroides L. in Ili River Valley.

LIU Ying1,2, ZHAO Yu1,2, MUNIR3, LI Wen-hui3

2017, 36(4):  910-915. 

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Canopy seed banks and delayed release adaptations are particularly prominent in sandy ecosystems. In this study, we investigated the size, seed vigor, supplementary effect on soil seed bank, and the retention dynamics of Sophora alopecuroide canopy seed bank in a desert grassland of Huocheng County, Xinjiang. The result showed that canopy had 271±124 beans·m^-2, and the number of complete seeds reached 144±138 beans·m^-2 which contributed to the canopy seed bank. After mechanical damage, the germination rate reached 76.98%±11.89%, seed vigor index was 72.44±39.01, which indicated that canopy seed bank could keep higher seed vigor. Canopy seed bank lasted about nine months. As a result, canopy seed bank could be an effective supplement to the soil seed bank, and both of them performed as effective supply bank of propagules during population regeneration and community succession. The results would be helpful to understand the reproductive characteristics, reveal the bioecological mechanism of its malignant invasion, and provide theoretical support for management of grassland ecosystem in the Ili River Valley.

 

Seasonal variation in photosynthetic parameters of Artemisia ordosica in relation to leaf nitrogen and specific leaf area.

WANG Zi-qi, ZHA Tian-shan, JIA Xin*, WU Ya-juan, ZHANG Ming-yan, MU Jia-wei

2017, 36(4):  916-924. 

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Understanding the seasonal dynamics of photosynthetic capacity of plants and its relationship with leaf traits is of great significance for accurate simulation of ecosystem carbon cycle. In this study, we measured in situ photosynthetic light and CO₂ response curves of Artemisia ordosica over an entire growing season in the Mu Us Desert, and analyzed the relationship of leaf nitrogen content (N_mass), specific leaf area (SLA) with the photosynthetic parameters of A. ordosica. As a result, the maximum net photosynthetic rate (P_nmax), apparent quantum yield (α), maximum carboxylation rate (V_cmax), maximum electron transportation rate (J_max) were relatively higher in the late spring and early autumn in the growing season, largely fluctuated in summer. P_nmax, α, V_cmax and J_max ranged as 13.79-33.31 μmol CO₂·m^-2·s^-1, 0.020-0.053 mol·mol^-1, 27.25-89.10 μmol·m^-2·s^-1 and 24.19-62.18 μmol CO₂·m^-2·s^-1, and averaged at 23.77 μmol CO₂·m^-2·s^-1, 0.037 mol·mol^-1, 56.29 μmol·m^-2·s^-1 and 42.44 μmol CO₂·m^-2·s^-1 respectively. The light compensation point (LCP) and CO₂ compensation point (C_o) did not change significantly over the growing season. Correlation analysis showed that photosynthetic parameters P_nmax, V_cmax and J_max were positively correlated with N_mass and SLA. The results further confirmed that the N_mass and SLA were important factors affecting the photosynthetic capacity of A. ordosica. The relationship between photosynthetic parameters and leaf traits obtained in this study can be used to help build parametric models of ecosystem processes.

 

Relationships between multi-stem type and stand density, tree growth index and mast year cone yield in Pinus koraiensis plantation.

NGUYEN Thanh-tuan1,2, SHEN Hai-long1*, ZHANG Jin-hu1, WANG Long1, ZHANG Peng1

2017, 36(4):  925-934. 

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A study was carried out to assess the influence of multi-stem phenomenon on cumulative volume and cone yield in 40-year-old Pinus koraiensis plantations. Four stand density levels (600, 750, 900 and 1200 trees·hm^-2) were sampled (15 plots in 25 m×40 m) to determine the relationships between stem types (single stem, two branching stems, and three or more branching stems) and stand density, tree height, diameter at breast height (DBH), crown diameter, mast year cone yield using one variable Logistic model and Meta analysis. The frequency of multistemmed trees decreased as the stand density increased. The frequencies in the stands of 750, 900, 1200 trees·hm^-2 were reduced by 24%, 51% and 59%, respectively compared with that in the stand of 600 trees·hm^-2. The frequency of double multi-stemmed type that exceeded 60% was the highest among the three multistemmed types. The multistem phenomenon had significantly promoting effect on DBH, tree height, crown diameter and cone number per tree by increasing 2.12%, 4.69%, 4.89% and 29.57%, respectively, compared with non multistemmed trees. The multistemmed types had different effects on cone production and tree height, DBH and crown diameter. The DBH, tree height, crown diameter and cone number per tree of single multistemmed trees were 1.49%, 1.99%, 1.47% and 20.64% higher than those of non multistemmed trees, respectively, but there were no significant differences. The doublestemmed and multiplestemmed trees had significant positive effect on cone production and stand growth indexes. The tree height of doublestemmed tree and multiplestemmed trees were increased by 2.07% and 2.90%, respectively; the DBH increased by 6.00% and 6.09% respectively; the crown diameters increased by  6.29% and 5.99%, respectively; the cone number per tree increased by  34.61% and 26.22%, respectively. In conclusion, the results of Logistic regression and Meta analysis suggested that the multistemmed trees had evident promotion effect on cone production, in which multiplestemmed trees and doublestemmed trees had more significant effect on tree growth and cone production. The multistem effects decreased with the increasing stand density. The highest multistemmed effect was observed in 40-year-old Korean pine plantation with the stand density of 600-750 trees·hm-2.

Responses of growth, photosynthesis and nonstructural carbohydrate of Quercus aliena var. acuteserrata seedlings to shading and simulated sunfleck.

CHEN Zhi-cheng1, LIU Xiao-jing2,3, LIU Chang4, WAN Xian-chong1*

2017, 36(4):  935-943. 

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In recent years, it has been found that Quercus aliena var. acuteserrata mature forests in Baotianman Mountains in southwestern Henan Province in China are difficult to regenerate. This study aims to explore the reasons why Q. aliena could not well regenerate by investigating the effects of different light environments on photosynthetic characters and nonstructural carbohydrate (NSC) of Q. aliena seedlings, and to discuss the impact of sunfleck on Q. aliena regeneration. In this study, sunfleck was simulated by opening shading apparatus at noon every day. Five treatments were set up: control (CK, natural sunlight) and four shading treatments including shade by 80% with opening one hour at noon (T80-1), shade by 80% (T80), shade by 98% sunshine with opening one hour at noon (T98-1) and shade of 98% sunshine (T98). Dry matter yield, NSC of Q. aliena seedlings, gas exchanges in photosynthetically active radiation (PAR) under 1500 μmol·m^-2·s^-1, photosynthesisPAR curves, diurnal variation of photosynthesis and chlorophyll fluorescence parameters of the leaves were measured. The dry matter yield and total NSC content of Q. aliena seedlings in shaded treatments were significantly lower than those of CK. The NSC content of seedlings under simulated sunfleck treatments was significantly higher than that of the seedlings with corresponding only shading treatments. Serious shading treatment (T98) resulted in higher death rate of seedlings. Different light environments had significant effects on photosynthetic capacity of Q. aliena seedlings. The net photosynthetic rates (P_n) of T80, T98-1 and T98 were significantly lower than CK under high PAR because of nonstomatal limitation in the shading treated seedlings. The efficiency of photochemical reaction of T98 was the lowest among all treatments. Q. aliena seedlings showed the ability of shade tolerance to some degree, such as lower light compensation point and dark respiration rate in shaded treatments, and T98 had higher P_n than T98-1. In summary, Q. aliena seedlings had difficulty to maintain the balance of carbon and to survive in seriously shading environment. However, sunfleck relieved the negative influences of carbon reserves of Q. aliena seedlings in shading environment, and had significant effects on building up high photosynthetic capacity of seedlings under high light conditions.

Effects of elevated O₃ concentration on photosynthetic physiological characteristics of Catalpa ovata.

XIONG Dong-lan1,2, LI Jing4, XU Sheng2,3*, HE Xing-yuan2, DENG Li-lan1, CHEN Wei2, HUANG Yan-qing2, FU Wei2

2017, 36(4):  944-950. 

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By using opentop chambers (OTCs), this paper studied the effects of elevated O₃ concentration on the growth and photosynthesis of Catalpa ovata, a common greening tree species in Shenyang City. The results showed that elevated O₃ concentration significantly inhibited the growth of C. ovata. Compared to the ambient air control, relative water content, dry weight, fresh weight, specific leaf weight, dry weight increment and fresh weight increment were significantly decreased in leaves of C. ovata after 20 days exposure to O₃ (160 nmol·mol^-1). The net photosynthetic rate (P_n) of C. ovata gradually decreased with the extension of time. The decrease in photosynthesis of C. ovata was related to nonstomatal factors. The change trends of intercellular CO₂ concentration (C_i) and transpiration rate (T_r) and stomatal conductance (G_s) were consistent, with decline first and then increase. The maximal photochemistry efficiency of PSⅡ (F_v/F_m) and quantum yield of PSⅡ electron transport (Φ_PSⅡ) decreased significantly over the time (P<0.05), the decline of C. ovata photosynthesis correlated markedly with the excess of light energy, and photoinhibition phenomenon under O₃ stress. Superoxide dismutase (SOD) and ascorbic acid peroxidase (APX) activities showed no significant change during the whole O₃ stress, which implied that it was quite difficult for C. ovata to tolerate excessive O₃ concentration, and two antioxidant enzymes did not make positive physiological response to the acute stress of O₃.

Shading, cooling and humidifying effects of urban forests in Harbin City and possible association with various factors.

ZHANG Bo1, WANG Wen-jie1,2*, HE Xing-yuan2, ZHOU Wei1,2, XIAO Lu1, LV Hai-liang2, WEI Chen-hui2

2017, 36(4):  951-961. 

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In this paper, a total of 183 plots distributed in Harbin urban region were selected, and 4 different forest types (affiliated forests, AF; roadside forests, RF; landscape forests, LF and ecological welfare forests, EF) were classified, and tree growthrelated parameters and environmental factors (inside and outside the forest) were measured simultaneously. The aims of this study were to find differences between the 4 forests types in shading, cooling and humidifying effects and their associations with the environmental and tree growth characteristics. We found that urban forests produced a 77%-90% reduction of sun lights (shading effect) and a 3%-6% increase in relative humidity (humidifying effect). The forests had a horizontal cooling effect of around 3 ℃ lower than open sites (outside forests). Soil cooling effect was 1-2 ℃ lower under canopy than in outside forests. The vertical cooling effect characterized as canopy temperature about 1 ℃ lower than under canopy temperature. Shading, cooling and humidifying effects significantly differed among the four forest types. The comprehensive scores for all these microclimate regulations demonstrated that LF was 19% higher than the other three forest types on average. Urban forests had much stronger regulating functions at high air temperature, low air humidity and sunny days. Moreover, four treegrowth factors (tree height, canopy area, clear bole height and diameter at breast height) had significant influences on temperature reduction and relative humidity increase, and the general patterns were that larger trees usually accompany with higher regulating function. Our findings highlight that different forest types have dramatically different ecological service functions. For the landscape forests, we should continue to maintain its high ecological service function and strengthen the management of the forest types with low environmental regulation ability.

Responses of growth of Wedelia trilobata and W. chinensis to soil nutrients.

YUAN Wei-ying, FENG Jin, ZHANG Xiao-ya, AN Jing, GAO Jun-qin*

2017, 36(4):  962-970. 

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Plant invasion seriously threatens the structure and function of ecosystems, and soil nutrient availability (soil nutrient amount and spatial heterogeneity) plays a key role in the successful invasion of introduced species. To explore the effect of soil nutrients on the growth of invasive and native species, a greenhouse experiment was conducted with the invasive species (Wedelia trilobata) and its native congener (W. chinensis) under monoculture and mixture in homogeneous soil environments of three nutrient levels and one heterogeneous environment. Growth measures (e.g., total biomass, root mass, stem mass, leaf mass, number of nodes, and root to shoot mass ratio were measured and the effect of soil nutrients was analyzed. Increased soil nutrient levels significantly promoted the growth of the two species. Soil nutrient heterogeneity improved the root mass and root to shoot mass ratio of W. trilobata, as well as the total biomass, root mass, and stem mass of W. chinensis. Soil nutrient level or nutrient heterogeneity had no significant impact on competition response of W. trilobata. We concluded that compared to its congener, W. trilobata had a higher probability to invade successfully in the higher homogeneous soil nutrient environment, and also in highnutrient patches of the heterogeneous soil nutrient environment.

Effects of thinning intensity on soil physicochemical properties of Larix kaempferi plantation in eastern Liaoning Province.

MA Fang-fang1,2, JIA Xiang3, ZHAO Wei4, ZHOU Wang-ming1, ZHOU Li1*, YU Da-pao1, WU Zhi-jun5, DAI Li-min1

2017, 36(4):  971-977. 

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The present study investigated the response of soil physical and chemical properties of the larch (Larix kaempferi) plantation to thinning intensity after five years in eastern mountainous area of Liaoning Province, through collecting soil sample from the topsoil (0-10 cm) and subsoil (10-20 cm) along a thinning gradient (CK, 20%, 30% and 40%). The results indicated that there were no significant variations in the soil bulk density, total porosity, capillary porosity, total C content, total N content, C∶N, N∶P, and NO₃^--N content under different thinning intensities, compared to the CK treatment. However, the soil waterholding capacity, total C content, total N content, N∶P, and active carbon content in the topsoil (0-10 cm) under the 40% thinning intensity were significantly higher than under the other two thinning intensities. Furthermore, 40% thinning intensity was beneficial to obtaining the largediameter wood. Therefore, the 40% thinning intensity was preferable to the management of the larch plantations in the eastern mountainous area of Liaoning Province.

Effects of cultivation duration on soil microbial functional diversity of artificial grassland in the ThreeRiver Headwater Region.

ZI Hong-biao1, LIU Min2, ADE Lu-ji1, HU Lei2, WANG Chang-ting2*

2017, 36(4):  978-987. 

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The objective of the current study is to reveal the changes of soil microbial functional diversity in the artificial grassland with different cultivation periods in the ThreeRiver Headwater Region, so as to provide evidence to ameliorate the degraded alpine meadow based on the efforts of planting artificial grassland. Three artificial grasslands with cultivation durations of 4, 8 and 12 years were selected. Soil nutrients and microbial functional diversity were determined using conventional laboratory analysis and the BiologECO microplate method. In the 0-10 cm soil layer, soil pH and total nitrogen (TN) content were significantly greater with 4 cultivation years than with the other cultivation years, while total potassium (TK) and available nutrients increased with increasing cultivation years (P<0.05). In the 10-20 cm soil layer, soil pH was significantly higher in 4-year grassland than in the other grasslands, while TK in 12-year grassland was significantly lower than in the other grasslands (P<0.05). Additionally, available nitrogen (AN) and available potassium (AK) showed the following pattern: 8 years > 12 years > 4 years. In the 0-10 cm soil layer, average well color development (AWCD) value showed 8 years > 12 years > 4 years. But AWCD value increased with increasing cultivation years in the 10-20 cm soil layer. Soil microbial functional diversity showed that Shannon and Pielou index in 0-10 cm soil layer of the 12-year grassland were lowest, while in the 10-20 cm soil layer the least values were found in the 4-year grassland. McIntosh index increased with increasing cultivation years in the 10-20 cm soil layer. Principal component analysis (PCA) showed that amino acids were the main carbon source for maintaining soil microbial community. Redundancy analysis (RDA) indicated that soil organic carbon (SOC), TK, AN, AK and pH were the main factors influencing the metabolic rate of soil microbial community and microbial functional diversity. In summary, there were differences among soil microbial functional diversity in the artificial grasslands of different cultivation durations. Soil nutrient content, soil microbial community stability and ecological environment improved with increasing cultivation years.

Isolation, identification and biocontrol effect of antagonistic bacteria on Phytophthora capsici.

TAN Tai-meng1, LI Ji-lie1*, SHEN Ai-rong1,3, YAN Zhun2, ZHANG Meng-jun1, ZHU Jiu-xiang1, ZENG Liang-bin2*, ZHAO Meng-rui1

2017, 36(4):  988-994. 

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Bacteria were isolated and screened from the rhizosphere soil of healthy pepper to obtain antagonistic strains with strong inhibitory effect on Phytophthora capsici. This study aimed to provide a basis for utilization of biocontrol strains. Antagonistic strains were screened out by spread plate and dual culture method. Strains were identified by morphological, physiological and biochemical characteristics, and 16S rDNA sequences analysis. The biocontrol potential was determined by pot experiment. IBFCBF-4 was isolated from the soils, which showed strong inhibitory effect on P. capsici. And it also had strong antagonistic effect against other eight kinds of plant pathogens. This bacterium was identified as Bacillus subtilis by methods described above. Pot experiment showed the control efficiency was 64.28% on P. capsici, and the fresh weight of shoot and root increased by 45.2% and 34.3%, respectively, when compared with the control group. IBFCBF-4 had a strong biocontrol effect on P. capsici and a significant growthpromoting effect on pepper; it was of great development and utilization value for P. capsici control in the field.

Effects of passage through the digestive tract of long-eared hedgehog on caper seed water uptake and germination.

XIAO Li-rong, LIN Ying-ying, LIANG Tao, SHI Lei*

2017, 36(4):  995-1001. 

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Animal and plant interaction has been a hot topic in recent years, and studies on the role of animals on seed dispersal are an important area of research. One of the main mechanisms by which frugivores promote seed germination is the scarification effect of their digestive tracts on the seed coat, which increases the seed’s permeability to water and gas. The effect of passing through the digestive tract of longeared hedgehog (Hemiechinus auritus) on water uptake in the germination of the seeds of caper (Capparis spinosa) was examined in this study. Caper seeds that had been passed by the long-eared hedgehog and separated from its feces served as the experimental group, and caper seeds separated from fresh fruit served as the control group. The results showed that passage of the seeds through the longeared hedgehog digestive tract increased the quantity of their water uptake (0-12 h), the speed of water uptake (0-12 h), and both the total water uptake percentages (0-2 h, 10 h) and the water uptake percentage over time (0-2 h). The long-eared hedgehog digestive tract had no significant effect on the caper seed germination rate. However, the germination rate of caper seeds that had passed through the long-eared hedgehog digestive tract and then soaked in GA₃ was significantly higher than those of experimental group seeds that were soaked in GA₃, and their germination period was lengthened as well. The TTC test showed that there were no significant differences in caper seed viability between any of the tested groups. These results demonstrated that the effect of passage through the long-eared hedgehog digestive tract is to increase the water uptake capability and to break down the mechanical barriers of caper seeds, indirectly improving seed germination while having no effect on seed viability. Thus, the long-eared hedgehog is an animal with significant potential in caper seed dispersal.

Effects of five fishing taggers on biochemical parameters of Ctenopharyngodon idellus.

YU Li-xiong1,2, DUAN Xin-bin2, CHEN Da-qing2*, LUO Hong-wei1,2, LIU Shao-ping2, GAO Lei2

2017, 36(4):  1002-1008. 

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This study aims to assess the effects of five tagging methods on the biochemical para-meters of grass carps (Ctenopharyngodon idellus). The tagging methods include ultrasound mar-king, passive integrated transponder (PIT) marking, fluorescent marking, fins amputated marking, T-type marking, and control. One hundred and eight grass carps, with body length (18.54±2.04) cm and body weight (109.04±36.36) g, were randomly allocated into 6 groups, and each group contained three replications. Two blood samples were extracted randomly from each replication 1, 7 and 15 days after tagging. The results showed that levels of globulin (GLB), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in ultrasound marking group increased significantly 1 day after tagging. After 7 days, the level of chlorine (Cl) was elevated and GLB remained at high level, whereas the concentrations of ALT and AST declined to the normal level. After 15 days, the level of GLB declined but still remained higher than that in the control group. There was a significant increase in concentration of Cl in PIT marking group 7 days after tagging, and it declined to the normal level at day 15. The level of triglyceride (TG) in fins amputated marking group decreased significantly while the concentration of AST in T-type marking group increased significantly 1 day after tagging and both of them recovered at day 7. All of the biochemical parameters of fluorescent marking showed no significant difference as compared with the control group. In conclusion, fluorescent marking is appropriate for largescale tagging and the fish can be released soon after tagging. Grass carps with PIT marking, fins amputated marking or T-type marking are recommended to be kept for 7 days to eliminate the bad effects before release. Ultrasound marking has the greatest effect on the health status of grass carp, and it is advisable for fish to be kept at least for 15 days before release.

Effect of calcium carbonate content in substrate on spat settlement of Pacific oyster Crassostrea gigas.

FAN Rui-liang1,2, CHAO Min1, REN Guo-ping3, QUAN Wei-min1*

2017, 36(4):  1009-1013. 

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To understand whether calcium content in substrate of artificial reefs could affect oyster spat settlement, we designed a twofactor randomized experiment with calcium carbonate in different contents (four treatment levels: 5%, 20%, 40%, 60%) and oyster larvae abundances (low treatment group: 1 ind·mL^-1, high treatment group: 7-8 ind·mL^-1). The density and shell height of oyster spats attached onto experimental substrates were measured. The results showed that both calcium content and planktic larvae abundance significantly affected the density of settled oyster spats (P<0.05). Planktic larvae abundance in seawater had a significant effect on the shell height of settled oyster spats (P<0.05), but calcium content did not significantly affect the shell height of settled oyster spats (P>0.05). The substrate with calcium carbonate content of 20% showed the greatest inducing ability to settlement of oyster larvae, and attracted significantly greater oyster settlement than the experimental group of 60% (P<0.05). The density of settled oyster spats was greater in the high abundance of oyster larvae than in the low abundance (P<0.05) regardless of calcium carbonate content, while the contrast result was found for the shell height: high larval abundance treatment < low larval abundance treatment (P<0.05).

Effects of pH and temperature on carbon budget of Sinonovacula constricta.

HE Miao1,2, LAI Qi-fang1, YAO Zong-li1, SUI Yan-ming1, LU Jian-xue1, GAO Peng-cheng1, ZHOU Kai1

2017, 36(4):  1014-1019. 

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The purpose of this study was to estimate the effects of seawater acidification and elevated temperature on the carbon budget of clam Sinonovacula constricta. Adult clams were exposed to various treatments under conditions of three pH values and three temperatures. The ingestion, respiration, defecation, and excretion of S. constricta were detected. The results showed that the carbon source obtained by S. constricta was mainly consumed through breathing, and then they were directly discharged as dejection, with a small part being discharged by excretion. The remaining carbon was mainly used for growth and development. At 23 ℃, the utilization rate of carbon at pH 8.2 was greater than that at pH 7.6 and pH 7.9. In pH 8.2 seawater, the utilization rate of carbon reached the peak at 23 ℃ when the water temperature ranged from 15 ℃ to 31 ℃. Oneway ANOVA showed that the ingestion rate was significantly influenced by low pH and temperature (P<0.05). In 23 ℃ seawater, with pH declining, S. constricta fed less Isochrysis sphaerica. At pH 8.2, the ingestion rate reached the peak at 23 ℃ when temperature changed from 15 to 31 ℃. Moreover, the oxygen consumption was significantly influenced by low pH and temperature (P<0.05). In 23 ℃ seawater, the respiration rate declined with pH decreasing. At pH 8.2, the respiration rate reached the peak at 23 ℃ when the temperature ranged from 15 ℃ to 31 ℃. However, no significant differences in excretion rate and defecation rate under low pH and temperature were found in this study (P>0.05).

Spatial-temporal distribution and its influencing factors of vegetation net primary productivity in Guangxi Xijiang River basin.

RONG Jian1,2,3, HU Bao-qing1,2,3, YAN Yan1,2*

2017, 36(4):  1020-1028. 

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Vegetation net primary productivity (NPP) is one of the key factors determining the ecosystem functions in a basin. In this paper, the NPP of Guangxi Xijiang River basin was estimated by applying a model of CarnegieAmesStanford approach (CASA) with the time series data sets of MODIS, vegetation and meteorological data collected for the period from 2003 to 2012. Then the spatial and temporal patterns of NPP and its influencing factors were analyzed. The results indicated that: (1) the average annual NPP value from 2003 to 2012 in this basin was 524.67 g C·m^-2·a^-1. The high NPP values were mainly concentrated in the south and east while the low values in the central part. From the perspective of terrain, the areas in the valley plain had lower values of NPP but those areas in the hilly region had higher values. The NPP exhibited a significant variation among vegetation types. The evergreen broadleaf forest was the most productive with a NPP value of 788 g C·m^-2·a^-1, and the planting crop the least productive with a NPP value of 386 g C·m^-2·a^-1; (2) The average annual NPP value in this study area was in the range of 430.05-602.48 g C·m^-2·a^-1 from 2003 to 2012. Generally, NPP value exhibited a fluctuating and descending trend. In 88.89% of total study area, the NPP showed a decreasing trend. The NPP value was high from July to October and low from January to March. (3) The NPP was negatively correlated with annual average precipitation but positively correlated with annual average temperature. The correlation between NPP and meteorological elements (precipitation and temperature) was significant, with a multiple correlation coefficient value of 0.67.

Dynamic monitoring of desertification in the Tarim Basin based on RS and GIS techniques.

WANG Fei1,3, WU Zhao-peng1, WANG Yang2, JIAO Wei3, CHEN Ya-ning3*

2017, 36(4):  1029-1037. 

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The Tarim Basin is one of the regions with the most serious land desertification in China. In this study, the spatial and temporal variations of land desertification in the Tarim Basin during 2000-2014 were monitored and analyzed using RS and GIS technologies based on the vegetation coverage from Normalized Difference Vegetation Index (NDVI) data of MODIS. Besides, the impacts of climate change and human activities on the desertification for the Tarim Basin were investigated. The results showed that: (1) The Tarim Basin was characterized by the largest proportion of severe desertification (64.63%), followed by moderate desertification (17.70%), and slight desertification (9.95%), and nondesertification was the least (4.18%). The gravity center of the severe desertification migrated to the northeast part in the past 15 years, with a migration distance of 21.08 km. (2) During the past 15 years, the severe desertification area decreased at a rate of 0.0076 km²·a^-1. However, the moderate desertification area increased rapidly, with an average annual rate of 0.0169 km²·a^-1, the slight desertification area had a slightly increasing trend with a rate of 0.0093 km²·a^-1, and the proportion of nondesertification increased significantly with a rate of 0.0289 km²·a^-1. (3) The changes of desertification were the results of the interaction of climate change and landuse change. Annual precipitation was closely related to annual average vegetation coverage with a correlation coefficient of 0.45. At the same time, the expansion of cultivated land area, which had increased by 13.18×10³ km² during the last 15 years, accelerated the desertification processes of the peripheral oasis area.

Ecosystem services assessment of wetlands in Qingdao based on metaanalysis.

YANG Ling, KONG Fan-long, XI Min*, LI Yue, WANG Sen

2017, 36(4):  1038-1046. 

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To investigate the ecosystem service values of various wetland types in Qingdao, this paper used metaanalysis to estimate the ecosystem service value levels of various wetland types on the basis of wetland ecosystem service value transfer model, and explored the influence factors and effectiveness of the model. The results showed that the regression coefficients of independent variables such as pollution prevention method, cost control method, ecological value method, water conservation, and erosion control were positive, which had positive effects on wetland value in Qingdao. However, the regression coefficients of independent variables such as shadow price method, carbon tax method, travel cost method, marshes, and wetlands area were negative, which had negative effects on wetland value. The values of various wetland types were in order of onshore and offshore wetland (3.29×10⁴ yuan·hm^-2) > river wetland (2.38×10⁴ yuan·hm^-2) > constructed wetland (2.27×10⁴ yuan·hm^-2) > swamp wetland (1.77×10⁴ yuan·hm^-2). Compared with 1997, the value of wetland ecosystem services decreased by 0.801 billion yuan in Qingdao in 2012. The results indicated that the evaluation methods of the ecosystem service value, different ecosystem services, and the wetland area were the important aspects affecting the wetland ecosystem service value. Ecosystem service values of different types of wetland were different in Qingdao. People’s attention and protection effort, local consumption level and government investment were the main reason affecting wetland ecosystem service value per area unit. Compared with 1997, the reduction of offshore and coastal wetland ecosystem service value was the main reason for the decreased wetland ecosystem service value in Qingdao in 2012. Our results indicated that metaanalysis was a feasible method to evaluate wetland ecosystem service value when human and financial resources were restricted or valuation data was lacking.

Determination of cold and freezing injury grade index of wax apple.

CHEN Hui1*, YANG Kai1, LI Li-chun1, CHEN Fu-zi2, LIN Jing1, PENG Ji-da1, XU Ling3, HU Fei4

2017, 36(4):  1047-1052. 

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Based on 89 cold and freezing injury sample disaster data of wax apple from 2008 to 2014 in Fujian, Guangdong, Guangxi and Guizhou provinces, combined with the morphological standard of cold and freezing injury, the grade index of cold and freezing injury for wax apple was preliminarily obtained by using regression analysis method. Accordingly, the grade index was tested and verified by the morphological changes and physiological and ecological standard of wax apple, which were obtained in the geographical transplantation experiment of natural low temperature, the simulated low temperature experiment of artificial climate chamber, and the investigated disaster data of orchards in 2016. The cold and freezing injury grades of wax apple were determined as: T_min>5.5 ℃, without cold and freezing injury, normal growth; 3.0 ℃<T_min≤5.5 ℃, light injury; 1.0 ℃<T_min≤3.0 ℃, moderate injury; -1.5 ℃<T_min≤1.0 ℃, severe injury; T_min≤-1.5 ℃, most severe injury, no recovery or death. The grade index in this study was verified by the results of typical year experiment, geographical transplantation and artificial climate chamber experiment, with accuracy rates of more than 90%, which could be applied in practice.

Characterization of molecular composition and seasonal variation of natural organic matter in source water using Fourier transform ion cyclotron resonance mass spectrometry.

YANG Hong-xia*, CHEN Jun-liang, GAO Jin-xu, LIU Wei

2017, 36(4):  1053-1059. 

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Natural organic matter (NOM) is of great significance in water treatment processes. Concentrations and molecular compositions of NOM may vary significantly with time. In particular, the seasonal variations of NOM compositions are site specific and unique to individual source water. In this study, molecular compositions and seasonal variations of NOM in source water from Queshan Reservoir in Shandong were investigated by using electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). The results demonstrated that various C, H, O-only molecules were the major components in the source water NOM. The van Krevelen diagram showed that compounds corresponding to biopolymers such as lignin were the most abundant components in the source water NOM. From winter to summer, the H/C ratio decreased with a concomitant increase in double bond equivalent (DBE), indicating that the molecules in corresponding seasonal samples became more unsaturated. Understanding NOM compositions and its seasonal variations in source water will help to develop effective strategies for drinking water treatment operation and ensure to meet the requirements of drinking water quality.

Emergybased analysis of sustainability of tidal power plant in China: A case study of the Jiangxia tidal power.

TANG Shou-juan, ZHANG Li-xiao*, PANG Ming-yue, HAO Yan

2017, 36(4):  1060-1066. 

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Although endowed with abundant tidal resource, China’s tidal power generation industry has been largely lagging compared with other renewable energy alternatives such as small hydropower, photovoltaic power, wind power and biomass power. To probe the reasons behind this stagnancy, an emergy evaluation was conducted for the 4.1 MW Jiangxia Tidal Power Station (JTPS), the largest tidal power station in China and the fourth in the world. The evaluation results indicate that the total emergy use of this production system was 5.08×10^19 sej to generate 2.61×10¹³ J of electricity in 2014, of which renewable resources accounted for 17.77%. Thus, the transformity of electricity produced by this plant is 1.95×10⁶ sej·J^-1. The environmental loading ratio (ELR) and the emergy sustainability index (ESI) of the JTPS were 4.63 and 0.12 respectively, exhibiting a poorer environmental performance than other renewable energy power plants except photovoltaic power. These results reveal that tidal energy is a kind of lower quality and more decentralized energy and its current exploitation presents low environmental competitiveness. In such context, the development of tidal power in China should proceed with cautions and avoid largescale blind development. Nevertheless, R&D is needed to promote the technology development and ultimately utilize abundant tidal resource in an efficient and sustainable way.

Mercury and methylmercury concentrations and their influencing factors in soils of different types of wetlands of Liaohe Estuary.

ZHENG Dong-mei1,2*, YANG Ji-song1,2, LI Hang1,2, CHEN Su1,2, LI Hui-ying1,2

2017, 36(4):  1067-1071. 

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The distribution and conversion factors of soil total mercury and methylmercury in different types of wetlands in Liaohe Estuary (two sites: Sandaogou and Bijialing) were analyzed along plant natural succession to study the levels of total mercury and methylmercury and their influencing factors. The results showed that the concentration of total mercury ranged from 0.036 to 0.069 mg·kg^-1 and the concentration of methylmercury ranged from 0.77 to 2.56 μg·kg^-1 in different types of wetlands soil in Liaohe Estuary. The concentrations of total mercury and methylmercury were significantly lower in Sandaogou wetlands than in Bijialing wetlands. The concentrations of total mercury and methylmercury in surface soil gradually decreased from mudflats to Phragmites australis wetlands. The concentrations of total mercury and methylmercury gradually decreased from the surface soil layer to the deep soil layer in Ph. australis wetlands and Suaeda salsa wetlands. The concentration of total mercury showed a trend of increasedecreaseincrease along the soil profile in mudflats of Bijialing, while the concentration of methylmercury was decreasing overall. The concentration of total mercury had a significant correlation with methylmercury concentration and a positive correlation with concentrations of potassium and soluble salts.

Photocatalytic degradation of nitrobenzene in wastewater by Fe-doped nanostructured ZnO.

ZANG Shu-yan1, YU Bo1, FANG Zhi-hao1, ZHOU Man-man1, ZHANG Xin1, LIAN Bin2*

2017, 36(4):  1072-1078. 

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Photocatalytic degradation of nitrobenzene in wastewater by Fe-doped nanostructured ZnO suspended system was studied under a high voltage fluorescence mercury lamp. Effects of initial concentration of nitrobenzene, mass concentration of Zn_1-xFe_x-O, ratio of amount of substance between Zn and Fe, reaction temperature, initial pH and photodegradation time were investigated. The results showed that the removal of nitrobenzene was effective, the rate of photodegradation in aqueous solution followed firstorder kinetics, and activation energy (E_a) was 9.3 kJ·mol^-1. When mass concentration of Zn_1-xFe_x-O was 0.8 g·L^-1 (the molar ratio of Zn and Fe was 1∶99), the first order photodegradation rate constant of nitrobenzene (initial concentration was 400 mg·L^-1, reaction temperature was 30 ℃, reaction pH was 3.27) was 0.0136 min-1, irradiated by a 125 W  high voltage fluorescence mercury lamp in wastewater. The photodegradation rate constant of nitrobenzene was related to the influential factors mentioned above. More-over, the catalyst Zn_0.99Fe_0.01-O prepared by us significantly lowered activation energy and improved the effect of the photodegradation of nitrobenzene in contaminated wastewater.

Advance in algal ecotypes research.

PANG Yun-long, LIU Zheng-yi, LI Jia-lin, WANG Yin-chu, YU Shu-xian, QIN Song*

2017, 36(4):  1079-1086. 

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Algae distribute from the tropics to the poles, and are important marine primary producers. Some algae gradually form different ecotypes during their adaptation to different environmental conditions and environmental changes. In this article, the definition and research methods of algal ecotypes are summarized. Algal ecotypes should be determined according to their ecological niches, biological and genetic characteristics. Through analyzing the current situations and problems in this field, it is concluded that phenotypic traits can be used as reference factors, but not as absolute standards. A new floating ecotype is defined in Ulva (Enteromorpha) prolifera, after analyzing the environment of the Yellow Sea, genetic differences and biological characteristics of the floating population.

 

Review of nutrient enrichment and global warming effects on seagrasses.

LIU Wei-Yan1, HAN Qiu-Ying2*, TANG Yu-Qin3, SUN Xi-Yan2

2017, 36(4):  1087-1096. 

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Seagrass beds support important ecosystem services, such as sediment stabilization, water quality improvement and carbon sequestration. In recent years, seagrass beds have declined worldwide. Considering eutrophication and global warming, we summarized the effects of nutrient enrichment and global warming on seagrasses. In oligotrophic environments, nitrate and ammonium can promote seagrass growth. Nitrate enrichment can disturb carbon balance of seagrass tissues, therefore negatively impacting seagrasses because nitrate needs to be reduced into nitrite, and then transformed into amino acid by a series of metabolism processes. Higher concentration ammonium can induce seagrass decline due to its toxicity. Organic nitrogen, as selectable nitrogen source of seagrasses, is effectively complementary nitrogen for seagrass. Temperature, as one of the important variables, controls seagrasses distribution and growth. Modest nutrient enrichment can increase seagrass production in spring, but higher temperature and nutrient enrichment can inhibit seagrass growth in summer. Nutrient enrichment and higher temperature in summer also accelerate macroalgae blooms, resulting in light attenuation and shift from seagrasses to macroalgae ecosystems. Further directions of research on seagrasses should include seagrass bed observation in a long term, effects of organic nitrogen on seagrasses, combined effects of nutrient enrichment and increasing temperature on seagrasses, and responses of tropical seagrass respiration to global warming.

Advances in biosynthesis and degradation of indoleacetic acid in plants under heavy metal stress.

ZHANG Xue-mei, WANG Hai-juan, WANG Hong-bin*

2017, 36(4):  1097-1105. 

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Auxin plays an important role in regulating the growth and heavy metal resistance of plants. The healthy growth of plants is a result of the homeostasis of auxin and the balanced plant metabolism under heavy metal stress. The homeostasis of auxin is strictly regulated by its biosynthesis, conjugation, hydrolysis and catabolism. Some enzymes and genes involved in auxin biosynthesis and degradation have been identified or cloned. However, little information is available regarding the enzymes and genes concerning auxin biosynthesis and degradation under heavy metal stress. Understanding the mechanisms related to auxin biosynthesis and degradation under heavy metal stress will be helpful to properly regulate plant growth during phytoremediation. Taking indoleacetic acid (IAA, a main representative substance of auxin) as an example, this review focused on the recent advances in the mechanisms of IAA biosynthesis and degradation, and its existing forms in plants under heavy metal stress. Prospects in this field have been proposed from the viewpoints of the relative importance of IAA biosynthesis routes, the variation of IAA forms and their functions, and the interactions among different plant hormones.

Research progress on aluminum toxicity and its control in forest soilplant system.

XU Xiao-li1, ZHANG Jin-biao1,2*

2017, 36(4):  1106-1116. 

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Aluminum is the most abundant metal in the crust. More and more aluminum originally fixed in the forest soils has been transferred into active forms due to the environmental problems such as soil acidification, which led to the increase in its potential toxicity in forest plants. The potential toxicity of active aluminum in terrestrial ecosystems was a major factor leading to the forest degradation overspreading along Central Europe in the 1970s. This problem aroused concern in various countries. Studies on aluminum toxicity in forest soilplant system are very important for the protection of forest resource, the evaluation of aluminum toxicity in forest ecosystems and its control. This paper summarized researches on the chemical forms and distribution of aluminum in forest soils, the accumulation and chemical forms of aluminum in forest plants, the effects of aluminum on the growth, physiological processes and genetic factors of forest plants. Furthermore, the alleviation measures, including the control of soil acidity, addition of base cations, control of organic acid in rhizosphere soil, inoculation of mycorrhizal fungi, selection of suitable plants and mixed plantation, were also described. Accordingly, some suggestions for further research in this field were proposed: the threshold value of aluminum toxicity and risk assessment of aluminum toxicity, the subcellular distribution and chemical forms of aluminum and their relationship with aluminum phytotoxicity, and new alleviation measures.

Advances in the mechanism of crop disease control by intercropping.

ZHU Jin-hui1, DONG Kun2, YANG Zhi-xian3, DONG Yan1*

2017, 36(4):  1117-1126. 

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Reasonable intercropping is a natural barrier against plant disease epidemic. In recent years, using intercropping to control crop diseases has risen to become one of the most important issues in agriculture. Previous studies have mainly focused on field crop collocation patterns, efficient utilization of light, heat and nutrient resources, effects of disease control, and yield advantage. So far, the mechanism of disease control has been rarely summarized systematically. In this review, the control effect of intercropping on airborne and soilborne diseases were summarized first and then the mechanism of intercropping control of diseases, including host crop resistance, pathogens and environment (such as soil condition and canopy microclimate) were demonstrated. The mechanisms of disease suppression mainly include: (1) Nutrient absorption and utilization are promoted and the physiology and biochemistry characteristics of host crops are improved, and thus the resistance of crops to pathogens is increased by reasonable intercropping. (2) On one hand, the diversity of aboveground crops are increased by intercropping and thus physical barrier is formed to block pathogen spread; on the other hand, the increased diversity of root exudates in intercropping systems directly allelopathically inhibit the growth of pathogens and reduce their survival and infection further. (3) The field microclimates (such as temperature, moisture and ventilation conditions) and the soil microecological environment (such as rhizosphere microflora, community structure and diversity as well as soil enzyme activities) are improved to enhance the disease control effect by intercropping. Finally, the limitations of research methods of crop disease control in intercropping systems were discussed and some research prospects in the future were also put forward.

Threedimension structure model of the costal Metasequoia glyptostroboides shelterbelts.

ZHANG Lei1, ZHANG Peng1, WANG Hua2, ZHOU Xin-hua3, YU Mu-kui1, WU Tong-gui1*

2017, 36(4):  1127-1133. 

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In order to clarify the structure features of Metasequoia glyptostroboides shelterbelts and improve the prediction accuracy of windbreak effect, we measured the vegetative surface area and volume of the trunks, branches and leaves and established the threedimensional structure model of M. glyptostroboides stands. The results showed that the vegetative surface area density ranged from 0.0012 to 3.4857 m²·m^-3, and the cubic density ranged from 0.000002 to 0.012397 m³·m^-3. Moreover, the crown shape and growth status were closely related with the shelterbelt structure. And the structure was heterogeneous in space: the surface and volume of branches and leaves reached a maximum value at the middle of the crown, but for the trunk, they gathered at the lower part. Meanwhile, the vegetative surface area density changed with the shapes of trunks, braches and leaves. The trunk had big volume (accounting for 75.28% of the total volume) but less vegetative surface area (accounting for 5.57% of the total surface area), the leaves had big surface area (accounting for 78.39% of the total surface area) but less volume (accounting for 3.87% of the total volume). The ratio of surface to volume was ranked in the order of leaves (20.23) > branches (0.77) > trunks (0.07). Compared with previous studies, our model could describe the structure much more comprehensively, which was much closer to the real structure of the shelterbelts. Additionally, owing to the different influences of wind, each component had different aerodynamic effects. Thus, using both vegetative surface area density and cubic density to parameterize the shelterbelts structure could reflect the different effects of each component on wind and better exhibit the aerodynamic effect of the shelterbelts.

Spatial structure optimizing model of stand thinning of Cunninghamia lanceolata ecological forest.

CAO Xiao-yu, LI Jing-ping, HU Yuan-jie, YANG Jing

2017, 36(4):  1134-1141. 

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The methods of multiplication and division were adopted to carry out the multiobjective programming and to determine the objective function so as to optimize stand spatial structure for the total mingling, forest layer index, W_V_Hegyi competition index, uniform angle index, and open degree, taking spatial structure and nonspatial structure as constraints. The model of stand thinning spatial structure optimizing model of Cunninghamia lanceolata ecological forest was built based on the determination of stand spatial structure constraint conditions priority by using grey relation method. This model was then used to determine the optimal solution of stand thinning spatial structure optimization of C. lanceolata ecological forest. The results showed that the stand spatial structure optimization objective function values of C. lanceolata ecological forest followed the order of total mingling (0.7016) > forest layer index (0.7008) > uniform angle index (0.6578) > open degree (0.5960) > W_V_Hegyi competition index (0.5785). Therefore, when considering stand spatial structure constraint condition before stand thinning, we must consider mingling firstly, followed by the forest layer index. The model was used in plots (20 m×30 m), where 14 optimally cutting trees were chosen with a thinning intensity of 14.1%. After thinning, the numbers of diameter class and tree species that describe nonspatial structure remained unchanged; stand mingling was increased by 2.71%, and species spatial isolation level was enhanced; forest layer index was increased by 10.91%, stand vertical hierarchical structure was improved greatly; W_V_Hegyi competition index was reduced by 8.64%, which showed a decline in stand competition pressure; uniform angle index was reduced by 8.25%, which showed a tendency of random distribution in stand spatial structure; open degree increased by 11.98%, which showed an improvement of light transmission. The objective function Q(g) value of stand spatial structure optimization model was increased by 12.18%.

Optimization of resource distribution of forest fire management in southern Fujian based on ArcGIS.

YANG Xia-jie1,2, SU Zhang-wen1,2, Tian Chao1,2, JIN Quan-feng1,2, GUO Fu-tao1,2*

2017, 36(4):  1142-1149. 

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To investigate the factors responsible for forest fires in major cities of southern Fujian from 2000-2010, logistic regression model and ArcGIS application were carried out. Climate, vegetation, terrain, population density, and socioeconomic factors were considered in this study. Watchtower locations and fire management divisions were also analyzed. The results revealed that 12 factors including elevation, slope, daily minimum relative humidity, the distance to railway, the distance to highway, the distance to the nearest residential area, daily maximum surface temperature, daily minimum surface temperature, daily precipitation, sunshine duration, daily maximum temperature and GDP were significantly correlated with forest fires. The forecast accuracy of the regression model exhibited 74.0%. The fire danger grading with the model was also investigated and found that areas of high fire dangers took up 33.58% and these fire dangers were distributed unevenly. Watchtower site selection results showed that visible rates of traditional way, 20 km × 20 km gridding, and 10 km × 10 km gridding were 25.63%, 42.25% and 63.38% respectively for the high fire danger area. As for the division of forest fire protection and extinguishing area, the results form AHP showed that weights of the distances to high fire risk areas, roads and residential areas were 0.620, 0.284 and 0.096, respectively. By weighted superposition, the corresponding division map of forest fire protection and extinguishing area was made by ArcGIS. The results can provide some support for forest fire prevention and management in mountainous regions of southern China.

Hyperspectal predicting model of chlorophyll content of Stellera chamaejasme in Qinghai Province.

KAI Nan1, LIU Yong-mei1*, LI Jing-zhong1,2, CHANG Wei1, XIE Xiao-yan1

2017, 36(4):  1150-1157. 

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Chlorophyll content is an important indicator of plant growth. The chlorophyll content of Stellera chamaejasme can provide a basis for both monitoring the growth and controlling the hazard of S. chamaejasme. A typical degraded meadow, which was dominated by S. chamaejasme in Xinghai County, Qinghai Province, was chosen for the experiment. Five methods were adopted to predict, contrast and analyze the SPAD values so as to construct the optimal prediction model of the chlorophyll content of S. chamaejasme in Qinghai Province, which included partial least squares (PLS) in the whole wavelength region of 400-1000 nm, multiple linear regression (MLR) and PLS based on successive projections algorithm (SPA), the red edge parameters and vegetation index. Results indicated that the optimal prediction performance was achieved by SPA-PLS model that was established by 9 characteristic wavelengths with SPA algorithm, and the correlation coefficient was predicted as 0.778, while the root mean square error was 1.895. Compared with the PLS model built on the full spectrum, the SPA-PLS model significantly reduced the computational complexity and improved the modeling efficiency. Compared with the SPA-MLR model, SPA-PLS model effectively solved the collinear problem among variables and also improved the forecasting accuracy, thus, it was the best model for predicting chlorophyll content of S. chamaejasme. Among predicting models built on the red edge parameters and vegetation index, a model constructed by MCARI index possessed the highest predicting accuracy with a correlation coefficient of 0.808 and a root mean square error of 1.969. Consequently, it could be the optimal vegetation index for inversing chlorophyll content of S. chamaejasme.

Applying fast independent component analysis algorithm of blind source separation method to remove soil effects on hyperspectral data for wheat biomass estimation.

LI Yan-li1,2, WU Shi-wen1,2, LIU Ya1, WANG Chang-kun1, LIU Jie1,2, XU Ai-ai1,2, PAN Xian-zhang1*

2017, 36(4):  1158-1164. 

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Hyperspectral technique has been an effective method to monitor the vegetation biomass as a rapid and nondestructive approach. However, the accuracy of biomass estimation is always limited by the influence of soil background. The purpose of this study aimed to alleviate the effects of soil on spectra and improve the accuracy of wheat biomass estimation based on the extracted vegetation spectra by blind source separation (BSS) method. In this study, with the application of fast independent component analysis (FastICA), pure vegetation spectra were extracted from the 110 groups of original fieldobserved canopy spectra, and the wheat biomass estimation accuracy were compared before and after FastICA with the partial least squares regression (PLSR). The results showed that the FastICA method could separate the soil spectra and vegetation spectra effectively, and the accuracy of wheat biomass estimation was significantly improved based on the extracted vegetation spectra, as compared with the original spectral, with the improvement of the ratio of performance to deviation of the calibration (RPD_c) and the ratio of performance to deviation of the cross calibration (RPD_cv) from 1.83 and 1.64 to 2.77 and 2.09, respectively. These results indicated that FastICA method could be applied as an effective spectral preprocessing method to significantly improve the accuracy of biomass estimation, thus providing guidance for accurate regional monitoring of wheat biomass by hyperspectral technology.

Layout optimization of tourism resort lands based on stress ecology theory: A case study of Wuyishan national tourist resort.

WANG Jian-ying1, ZOU Li-lin2, HUANG Yuan-shui1*, YE Xin-cai1

2017, 36(4):  1165-1172. 

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Ecological environment is the core attraction of tourist resort; therefore, it is very important to optimize the resort landuse distribution in terms of ecological environment protection. In this paper, an ecological stress evaluation model was built based on stress ecology theory, thereby the ecological stress level of Wuyishan Mount national tourist resort was evaluated, and the land distribution pattern under the restriction of ecological stress was simulated by CA-Markov model. The comprehensive ecological stress index of the study area was 0.0685 in 2015, showing a severe stress state. Water body, grassland and unused land were also seriously stressed, while cultivated land, garden land and forest land were in a slightly stressed state, and tourism lands except entertainment land also faced a serious stress. Simulated results suggest that in 2025, tourism lands (such as entertainment land, residential land and traffic land) would be characterized mainly by an increasing trend, with gradual outward expansion around the existing lands, whereas the ecological land except water body would be reduced and the fragmentation degree would be improved significantly. In future, differential strategies such as increasing vs. decreasing, utilizing vs. protecting, rigid vs. flexible, and hardening vs. softening corresponding to stress degrees should be taken to develop Wuyishan Mount national tourist resort. The layout optimization of tourism resort lands based on the evaluation of ecological stress could balance the tourism development and ecological protection harmoniously.