Table of Content

10 October 2012, Volume 31 Issue 10

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Articles

Impacts of species composition, richness, sowing density, and soil nutrients on the complementary effect of plant communities.

LI Ang1**, ZHANG Ming1, DU Guo-zhen2

2012, 31(10):  2443-2448. 

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Taking the common perennial grass species Elymus nutans, Festuca sinensis, and Festuca ovina widely distributed over the alpine grassland of QinghaiTibetan Plateau as test materials, and through establishing different mono and mixed cultured species combinations, a fiveyear continuous measurement of the plant community productivity was conducted, aimed to understand the effects of species composition, richness, sowing density, and soil nutrients on the  complementary effect of plant communities, and how the  complementary effect changed with time. The results indicated that species composition had significant effects on the  complementary effect of plant communities. When the soil nutrients were richer, the plant communities with higher species richness had higher  complementary effect. With increasing sowing density, the  complementary effect had a decreasing trend at the initial stage, but did not vary significantly in subsequent years. Fertilization increased the  complementary effect significantly, and this effect tended to be increased with the increasing years of plant growth.

Morphological variation of Lithocarpus glaber seeds in evergreen broadleaved forest at its different succession stages in Gutian Mountain, Zhejiang Province of East China.

HU Xing-hua1,2**, REN Yong-li1, ZHANG Yu-xuan1

2012, 31(10):  2449-2454. 

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By substituting spatial difference for temporal change, this paper studied the morphological variation patterns of Lithocarpus glaber seeds in evergreen broadleaved forest during the succession of plant communities in Gutian Mountain of Zhejiang Province, and the redundancy analysis (RDA) was adopted to analyze the relationships between the seed morphological characteristics and ecological factors. The results indicated that succession stage explained the majority of the variation of the seed morphology (P<0.001), elevation was ranked as the second (P<0.001), while slope had minor effects on the variation. With the succession of the plant communities, the coefficients of variation of the L. glaber seed length, seed diameter, and seed volume all increased significantly (P<0.001). Furthermore, the proportion of the second grade seeds declined with succession, while the proportions of the first grade seeds and third grade seeds increased steadily, resulting in the polarization of seed size at the late succession stage. The proportion of empty seeds increased gradually with succession, leading to the significantly higher empty seed percentage at middle succession stage than at early succession stage (P<0.001), and also, at late succession stage than at middle succession stage (P<0.001). It was speculated that the morphological variation of L. glaber seeds could be attributed to the changes in the light environment and community structure during the process of succession. Further analysis revealed that the seed morphological characters of L. glaber at the late succession stage of plant communities could lead to the severe regeneration barrier for L. glaber, which might explain the observed regeneration failure of this species.

Biomass, carbon accumulation and its partitioning of a Pinus tabulaeformis plantation ecosystem in Shanxi Province, China.

CHENG Xiao-qin, HAN Hai-rong**, KANG Feng-feng

2012, 31(10):  2455-2460. 

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Pinus tabulaeformis(Carr.) is one of the main forestation tree species in northern China. To accurately estimate the biomass and carbon storage of P. tabulaeformis plantation ecosystem is critical to the study of the carbon sequestration function of regional P. tabulaeformis plantations. By using plot sampling method, this paper measured the biomass, carbon storage, and carbon partitioning of a 38-year-old P. tabulaeformis plantation in Shanxi Province, and estimated the net productivity and annual net carbon sequestration of the plantation. It was found that the biomass of the individual tree was closely correlated with the diameter at breast height and tree height. The mean stand biomass was 145.35 t·hm^-2, of which, tree layer biomass was 123.98 t·hm^-2, accounting for 85.30% of the total. The carbon content in various components of the plantation ecosystem was 0.5032 g C·g^-1 in stem, 0.4887 g C·g^-1 in bark, 0.5414 g C·g^-1 in branch, 0.4774 g C·g^-1 in leaf, 0.4862 g C·g^-1 in root, 0.4468 g C·g^-1 in shrub layer, 0.4417 C·g^-1 in herb layer, 0.4112 g C·g^-1 in litter layer, and 0.0090 g C·g^-1 in soil layer (0-100 cm), and the soil carbon content was decreased gradually with depth. The total carbon storage of the plantation ecosystem was 172.95 t·hm^-2, and the carbon storage of each layer was in the order of soil layer (102.07 t·hm^-2) > tree layer (62.08 t·hm^-2) > litter layer (7.75 t·hm^-2) > shrub layer (0.58 t·hm^-2) > herb layer (0.47 t·hm^-2). The carbon storage in different tree organs was positively correlated with their biomass. Stem had the highest biomass, and its carbon storage was also the greatest, accounting for 58.80% of the tree layer’s. The plantation had an annual net productivity of 10.19 t·hm^-2·a^-1, and its annual net carbon sequestration was 5.03 t C·hm^-2·a^-1.

Responses of soil respiration rate in Chinese fir plantation to the changes of heat and moisture condition.

WANG Na1, HUANG Yi-xiong1**, YE Gong-fu2, SUN Yue1, WANG Liang1

2012, 31(10):  2461-2465. 

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By using Li-8100, this paper studied the dynamic variations of soil respiration in a Chinese fir plantation in Jianyang of Fujian Province, East China during weather change. The soil respiration rate in the plantation had a similar variation trend with soil temperature, but the peak value of the soil respiration rate occurred at different time under different weather conditions. Normally, the peak value occurred at about 13:00, but appeared at 11:00 when the air temperature and precipitation had obvious change. The diurnal variation range of the soil respiration rate also varied under different weather conditions, being 37.9% and 50.6% at lower temperature and higher temperature, respectively. In companying with great extent of cooling and raining, the soil respiration rate decreased sharply, with the minimum on the fifth day after the weather change, and then increased with rising temperature, taking 10 days from decrease to recover. The soil respiration rate showed a significant positive correlation with the surface soil temperature, and a negative correlation with the soil moisture content.  

Dynamics of soil respiration under Phragmites australis community in dry habitats of Songnen Plain and related affecting factors.

WANG Ming1,2, LIU Xing-tu1, LI Xiujun1**, ZHANG Ji-tao1, WANG Guo-dong1,2

2012, 31(10):  2466-2472. 

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Soil respiration is one of the important components in global carbon cycle, and a sensitive indicator of many soil processes that control soil metabolism. In order to understand the dynamics of soil respiration under the Phragmites australis community in dry habitats of Songnen Plain, Northeast China, a field observation on the soil respiration was conducted from May to October 2011 by using LI-6400 automated soil CO₂ flux system. There existed obvious diurnal and seasonal patterns of the soil respiration. The diurnal curve of the soil respiration was unimodal, with the peak appeared at 11:00-13:00, and the seasonal change of the soil respiration was with the maximum (4.8 μmol·m^-2·s^-1) in July and August and the minimum (1.51 μmol·m^-2·s^-1) in October. The main factor affecting the soil respiration was temperature. The soil respiration rate was significantly correlated with the nearground ambient air temperature and the soil temperature at depths 0-10, 10-20, and 20-30 cm, of which, nearground ambient air temperature and the soil temperature at depth 0-10 cm were the two most important controlling factors. The Q₁₀ values of the soil respiration from May to October varied from 1.2 to 1.65, with a mean value of 1.39 and a coefficient of variation of 15.4%. Soil moisture content and near-ground air humidity were not the main environmental factors affecting the soil respiration.

Effects of land use change on soil organic carbon and microbial biomass carbon and nitrogen in Naban River watershed, Yunnan Province of Southwest China.

GUO Fang-fang, LI Yong-mei, LI Zhao-li**, WANG Zi-lin

2012, 31(10):  2473-2478. 

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The land use change in tropical forest area, as compared to that in other areas, is more vital to global carbon cycle. Taking the Naban River watershed in Xishuangbanna of Yunnan as study area, and by the methods of field survey and laboratory analysis, this paper studied the effects of the land use change from natural forest to dry farmland, paddy field, rubber plantation, or tea garden on the soil organic carbon (SOC) and soil microbial biomass carbon (SMNC) and nitrogen (SMBN). The results showed that after the natural forest changed into other land use types, the SOC, SMBC, and SMBN decreased significantly, with the greatest decrements of SOC and SMBC in paddy field. The SOC, SMBC, and SMBN were significantly higher in latosolic red soils than in latosols. The SOC was significantly positively correlated with SMBC, SMBN, and soil moisture, and significantly negatively correlated with soil bulk density and soil pH. The SMBN was significantly positively correlated with SOC and SMBC, and significantly negatively correlated with soil bulk density. The ratio of SMBC to SOC was significantly positively correlated with soil pH.

Effects of roundup ready transgenic soybean on ammonia-oxidizing archaeal diversity in rhizospheric soil.

LIU Zhi-hua, XU Guang-hui, WANG Hong-yan**, LIU Jia

2012, 31(10):  2479-2485. 

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Roundup ready transgenic soybean [Glycine max (L.) Merr.] (RRS) is one of the genetically modified crops and firstly commercialized by the Monsanto Company. In recent years, more attention has been paid on the risk assessment of RRS, including the potential effects on soil biota diversity. Ammoniaoxidizing archaea (AOA) are a group of the key microbes in nitrification, playing an important role in N cycle. By using PCR-DGGE cloning, this paper studied the diversity of AOA communities in the rhizosphere soils of RRS, its non-transgenic parental isoline (RRS-S), wild soybean (W-S), and cultivated soybean (D-46), aimed to provide theoretical basis for the ecological safety assessment on the transgenic soybean. The RRS had no remarkable effects on the AOA diversity, based on the Shannon diversity index and evenness index. The principal components analysis and DGGE analysis showed that the AOA community structure in the rhizosphere of RRS was significantly different with that in the rhizosphere of WS and D-46, but had no significant difference with that in the rhizosphere of RRS-S. Moreover, the AOA amoA gene sequencing of DGGE bands and the phylogenetic analysis revealed that parts of the AOA in the rhizosphere of test soybean cultivars belonged to the clusters already reported in soil/sediment, others belonged to the unknown clusters or groups in soil, but none of them belonged to the clusters in water or sediment. There was little change in the DGGE bands, among which, bands 1, 20, and 25 were missing, and band 3 was specific for RRS. In conclusion, RRS had no apparent effect on the diversity of AOA in rhizosphere soils, but could alter the composition of AOA community.

Effects of transgenic Bt+CpTI insect-resistant cotton on microbial community diversity in rhizosphere soil.

WULAN Tu-ya1,2,3, ZHAO Jian-ning1,2, LI Gang1,2, HONG Mei3, LIU Hong-mei1,2, WANG Hui1,2, YANG Dian-lin1,2**

2012, 31(10):  2486-2492. 

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An experiment with transgenic Bt+CpTI cotton SGK321 and its parental isoline Shiyuan 321 was conducted to examine the effects of planting transgenic Bt+CpTI cotton on the soil microbial community diversity. Rhizosphere soil was sampled at different growth stages (30, 60, 90, and 120 d) of SGK321 and Shiyuan 321. The Biolog analysis showed that the average well color development (AWCD, reflecting soil microbial activity) of all carbon sources changed in the following patterns. As compared with that for Shiyuan 321, the AWCD for SGK321 was significantly higher (P<0.05) at the growth stage of 30 d but significantly lower at other growth stages (P<0.05). The Shannon richness index and Simpson’s dominance index of the soil microbial community changed differently during the growth of SGK321 and Shiyuan 321, whereas the evenness index had no significant difference at the four growth stages of the two cultivars. Principal component analysis indicated that at the SGK321 growth stage of 30 d and the Shiyuan 321 growth stages of 60 and 120 d, and also, at the SGK321 growth stages of 60, 90, and 120 d and the Shiyuan 321 growth stage of 30 d, the carbon sources utilization of soil microbial community was similar. The main carbon sources utilized by the soil microbes were carbohydrates, amino acids, carboxylic acids, and polymers.

Biomass allocation characteristics of differentaged Lycium barbarum in Jintai electrical irrigation area, Gansu Province of Northwest China.

LIU Rui, JIN Hu-jia**, MA Quan-lin, WANG Yao-lin, LI Yin-ke, SUN Tao, SONG De-wei, ZHU Guo-qing

2012, 31(10):  2493-2500. 

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Lycium barbarum L. is the top choice cash shrub planted on the saline soils in arid areas of China. To study the morphology and biomass allocation of L. barbarum could provide theoretical basis for enhancing the productivity of this shrub and supporting its sustainable use. In this paper, the L. barbarum plants of 4-, 7-, and 11-year old in the Jintai electrical irrigation area of Gansu were selected to study the biomass allocation in their branches, fruits, leaves, and different diameter sizes roots. Little variation was observed in the plant height and canopy diameter among the 4-year-old plants, greater variation was found among the 7-year-old plants (the vigorous growth stage), and little variation was observed again among the 11-year-old plants. Vertically, the total biomass and branch biomass of the 4-, 7-, and 11-year old plants were the greatest at the 50-100 cm layer, the fruit and leaf biomass of the 4-year old plants were the greatest at the 50-100 cm layer, whereas the fruit and leaf biomass of 7-year-old plants were the greatest at the 100-150 cm layer. The biomass of the thick and thin roots of the 4- and 7-yearold plants occupied a greater proportion, while the biomass of the thick roots of the 11-year-old plants occupied over 50% but the biomass of the thin roots only had a small proportion. The biomass allocation to the fruits, leaves, and medium and coarse roots increased with plant age, whereas the biomass allocation to the fine roots was the greatest for the 7-year-old plants, followed by the 11-year-old plants, and then the 4-year-old plants. A quadratic function was developed to describe the relationships between the leaf and root biomass and the plant age.

Effects of litter cover on soil evaporation in broadleaved Korean pine forest.

LIN Mao-sen1,2, GUAN De-xin1, JIN Chang-jie1, WANG An-zhi1**, Niu Li-hua1, WU Jia-bing1, YUAN Feng-hui1

2012, 31(10):  2501-2506. 

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By observing the soil evaporation under litter cover in broadleaved Korean pine forest, this paper studied the effects of the litters with different dry weights and at different decomposition stages on the soil evaporation as well as the relations between the soil evaporation and soil moisture content. The results showed that at the same soil moisture contents, the larger the litter cover, the smaller the soil evaporation was. The mitigation effect of the litter cover on the soil respiration differed with the decomposition stage of the litters, being decreased in the order of undecomposed, semidecomposed, and decomposed litters. There existed a logarithm relationship between the soil evaporation and the litter mass. With the decrease of soil moisture content, the soil evaporation reduced. When the soil moisture content was within the range of 38%-41%, each 1% decline of the moisture content induced the soil evaporation under the covering of 75 g, 45 g, and 15 g litters decreased by 2.38 g, 1.43 g, and 1.30 g, respectively, and, during the declining of the moisture content, the higher the decomposition rate of the litters, the lesser the decrement of the soil respiration.

Interspecific association of dominant species of wetland vegetation in the middle and lower reaches of Fenhe River, Shanxi province of China.

WANG Hui-min1, PANG Chun-hua1**, ZHANG Feng2, ZHAO Cai-li1

2012, 31(10):  2507-2512. 

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By using χ²test, Pearson’s correlation coefficient, and Spearman’s rank correlation coefficient, a quantitative study was made on the interspecific association among the 561 species pairs of 34 dominant plant species of wetland vegetation in the middle and lower reaches of Fenhe River. The χ²test showed that among the 561 species pairs, 178 pairs were positively while 256 pairs were negatively correlated, and the correlation ratio was 0.70. Pearson’s correlation coefficient test showed that 157 pairs were positively while 402 pairs were negatively correlated, and the correlation ratio was 0.39. Spearman’s rank correlation coefficient test showed that 216 pairs were positively while 343 pairs were negatively correlated, and the correlation ratio was 0.63. As compared with χ²test and Pearson’s correlation coefficient, Spearman’s rank correlation coefficient was more sensitive. Most of the total 561 species pairs did not show significant association. The results indicated that the wetland vegetation in the middle and lower reaches of Fenhe River was at the early stage of succession. According to the adaptation to the environment and the leading ecological factors, the 34 dominant species were divided into four ecological species groups.

Interspecific associations among tree species in natural deciduous broadleaved forests in western Qinling, Northwest China.

YANG Hai-yu1,2, ZHANG Song-zhi1,2**, LIU Xiao-lin1,2, PEI Hui-ming1,2, LIN Yan-xiong1,2

2012, 31(10):  2513-2520. 

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In order to understand the plant population growth status and community structure characteristics of natural deciduous broadleaved forests in Xiaolongshan region of western Qinling and to solve the selection issue of tree species in forest management, an investigation by the method of typical sampling was conducted on the deciduous broadleaved forest dominated by Quercus aliena var. acuteserrata from June to September 2009. The distributions of the tree species in this forest were investigated on small quadrat scale (10 m×10 m), the importance values of the tree species were calculated, and the interspecific associations among the 666 speciespairs of 37 tree species were quantitatively studied by 2×2 contingency table, variance ratio VR, Jaccard index, and χ² test. In the forest studied, Q. aliena var. acuteserrata had the highest importance value, while the others were the associated tree species. Overall, the 37 tree species showed positive associations, and the associations reached significant level. The χ² test showed there were 7 tree species pairs (1.05% of the total) presenting very significant association, 19 tree species pairs (2.85% of the total) presenting significant association, and 640 pairs (96.10% of the total) presenting no or insignificant association. In combining with the AC value, there were 5 pairs showing significant positive association, and 2 pairs showing significant negative association. The community was in a relatively stable stage of secondary succession. This study could provide guidance for the management of natural secondary forest and the selection of afforestation species.

Meteorological grading indices of water-saving irrigation for winter wheat.

XIAO Jing-jing1,2, HUO Zhi-guo1**, JIN Zhi-feng2, LI Na3, WANG Li1, LU Xiao-feng1，4, ZHANG Lei1

2012, 31(10):  2521-2528. 

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In this paper, the meteorological grading indices of water-saving irrigation for winter wheat at its different development stages were built, based on the principle of cropland water balance and the theories of insufficient irrigation and regulated deficit irrigation, and by using the multidimensional information, including the daybyday meteorological data in 1961-2008 from 560 meteorological stations, the every ten-day soil moisture data in 1993-2008 from 463 agro-meteorological stations (of which, the data in 1980-2008 came from 84 agrometeorological stations), and the yearbyyear irrigation amount and yield data. In combination with the product-water function (FAO-1979), the relationships of the water deficiency rate and water deficit quantity of winter wheat at the stages of sowingjointing, jointingheading, and heading-maturing and in the whole growth period with yield reduction rate were analyzed. During the whole growth period of winter wheat, the water-saving irrigation meteorological grading indices from I to Ⅲ levels of water deficiency rate and water deficit quantity (secondary indicator) were [15%, 30%), [30%, 50%), and ≥50%, corresponding to 1-2 irrigations (600 m³·hm^-2 each time), 2-4 irrigations, and >4 irrigations, respectively. At sowingjointing stage, the indices were [20%, 40%), [40%, 60%) and ≥60%, corresponding to 1 irrigation, 1-2 irrigations, and >2 irrigations; at jointing-heading stage, the indices were [15%, 30%), [30%, 45%) and ≥45%, corresponding to 0.5 irrigation, 1 irrigation, and >1 irrigation; and at heading-maturing stage, the indices were \[15%, 30%), \[30%, 50%) and ≥50%, corresponding to 1 irrigation, 1-2 irrigations, and >2 irrigations, respectively. These indices could supply scientific support for the optimization of irrigation, and give guidance to agricultural production

Fruit type spectra and their altitudinal distribution patterns of wild plants in Beijing.

YU Shun-li**, FANG Wei-wei, ZHANG Xiao-feng

2012, 31(10):  2529-2533. 

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The fruit type spectrum of terrestrial ecosystem is a result of long-term adaptation evolution to the environment. In this paper, the fruit type spectra of 1371 wild seed plants and their four life forms (tree, shrub, herb, and liana) in Beijing area were analyzed, and the distribution patterns of the fruit type spectra along an altitudinal gradient in Donglingshan Mountain in western Beijing were investigated. Among the fruit types of the seed plants, capsule was the dominant, followed by achene, nut, caryopsis, berry, and legume. The percentage of fleshy fruits was 13.57%, and that of dry fruits was 86.43%. Among the dry fruits, dehiscent fruits occupied 35.6%, and indehiscent fruits occupied 50.83%. Large differences occurred in the fruit type spectra of the 4 life forms. Nut was the dominant fruit type in trees, berry was the dominant fruit type in shrubs and lianas, and achene was the dominant fruit type in herbs. The percentages of fleshy fruits and dry fruits were 32.7% and 67.3% in trees, 49.2% and 50.8% in shrubs, 6.4% and 93.6% in herbs, and 52.2% and 47.8% in lianas, respectively. All these fruit type characteristics were related to the adaptation of the fruit types to the warm temperate climate and geographical position (higher altitude and lower altitude) in Beijing. In the Dongilingshan Mountain in western Beijing, the percentage of fleshy fruits decreased gradually from 18.52% at 1083 m alt. to zero at 2100 m alt., while the percentage of dry fruits increased gradually from 80.95% to 100% with rising altitude. The percentages of berry and drupe had significant negative relationships to altitude because the heat and moisture condition at increasing altitude became unfavorable to the growth of berry and drupe plants, but favorable to the achene and capsule plants. This study could have significance in understanding the relationships between the fruit type spectra of wild plants in Beijing area and the local climate as well as the longterm adaptation evolution of terrestrial ecosystems to their natural environment.

Effects of different irrigation modes on the photosynthetic function and antioxidant enzyme activities of ‘Hanfu’ apple leaves.

MA Huai-yu1, LU De-guo1**, LIU Guo-cheng1, QIN Si-jun1, KANG Li-quan2

2012, 31(10):  2534-2540. 

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Taking ‘Hanfu’ apple (Malus domestica Borkh.) as test material, this paper studied the effects of different irrigation modes, including regular irrigation (control), alternate half root-zone irrigation, half root-zone irrigation, and drought, on the photosynthetic function and antioxidant enzymes activities of apple leaves. Compared with the control, the other three irrigation modes had inhibitory effects on the leaf net photosynthetic rate (P_n) and stomatal conductance (G_s), with the effects decreased in the order of drought > half root-zone irrigation > alternate half root-zone irrigation. Alternate half root-zone irrigation, half root-zone irrigation, and drought all made the leaf chlorophyll content decreased obviously after an initial increase, with the peak on the 9th day, and the chlorophyll content was the lowest in drought treatment all along. Alternate half root-zone irrigation, half root-zone irrigation, and drought increased the leaf proline content throughout the experiment, with the highest proline content in drought treatment and the lowest one in alternate half root-zone irrigation treatment. Alternate half root-zone irrigation, half root-zone irrigation, and drought induced different changes in the leaf antioxidant enzymes activities. The SOD activity in drought treatment and half root-zone irrigation treatment increased markedly and reached a peak on the 9th day, and then decreased rapidly, while the SOD activity in alternate half rootzone irrigation treatment kept at a relatively higher level. In half root-zone irrigation and alternate half root-zone irrigation treatments, the POD and CAT activities showed a similar variation trend, i.e., increased to a peak on the 9th day, followed by a decline later. In contrast, the POD and CAT activities in drought treatment went up speedily first and remained relatively high after 9 days. All the treatments except the control increased the leaf electrical conductivity and MDA content, with the increments being the highest and reached the significant level in drought treatment, and the lowest in alternate half root-zone irrigation treatment. In short, alternate half root-zone irrigation could maintain relatively higher efficiency of photosynthesis on the basis of reduced irrigation amount, with lighter drought stress, which could realize the water-saving cultivation of fruit trees.  

Effects of high temperature stress on the flag leaf photosynthesis and chlorophyll fluorescence parameters of rice.

DU Yao-dong1,2, LI Jian-ling2, WANG Hua1, TANG Xiang-ru2, HU Fei2**

2012, 31(10):  2541-2548. 

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Super hybrid rice variety Tianyou 998 was pot-cultured in climate chambers to study the characteristics of its flag leaf photosynthesis and chlorophyll fluorescence parameters at four growth stages (heading, milking, waxmaturing, and full maturing) under high temperature stress. Five high temperature treatments were installed. The maximum temperature was installed at 32, 35, 38, 40, and 42  ℃, respectively, with a 6  ℃ difference per day, and each treatment was lasted for 5 days, 2 hours per day, and taking the natural condition as the control (CK). High temperature had obvious effects on the characteristics of the flag leaf photosynthesis and chlorophyll fluorescence parameters, and the effects differed with the high temperature treatments, rice development stages, and test items. The higher the temperature, the greater the effects were. After treated with high temperature, the test items such as chlorophyll content (SPAD), net photosynthetic rate (P_n), stomatal conductance (G_s), efficiency of PSII photochemistry (F_v/F_m), actual quantum yield (Φ_PSII), apparent photosynthetic electron transport rate (ETR), photochemical quenching coefficient (q_P), and photochemical reaction (P) decreased, while the intercellular CO₂ concentration (C_i), initial fluorescence (F_o), nonphotochemical quenching coefficient (q_N), and other heat dissipation (E) increased. Most of the photosynthetic and chlorophyll fluorescence parameters at the four growth stages changed significantly when the maximum temperature was above 35  ℃, and decreased greatly when the maximum temperature was above 38  ℃. At heading and milking stages, the P_n and G_s had a significant decrease while the C_i had a significant increase; at wax and full maturing stages, the SPAD decreased significantly. The decrement of the F_v/F_m and the decrement of the F_o were greater at heading and milking stages than at wax and full maturing stages. High temperature stress had greater effects on the P_n than on the SPAD. The decrease of the P_n at heading and milking stages was mainly induced by the stomatal factors, while the P_n decrease at wax and full maturing stages was mainly caused by the no-stomatal factors.

Effects of grafting on eggplant growth and antioxidant enzyme activities under carbendazim stress.

ZHOU Bao-li**, LI Juan, GAO Ping, MENG Zhao-hua, CHEN Zhi-xia

2012, 31(10):  2549-2554. 

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Taking the wild eggplant (Solanum torvum) as rootstock and the cultivated eggplant (S. melongena) cultivar ‘Xi’anlüqie’ as scion, this paper studied the fruits’ pesticide residue, growth indices, and antioxidant enzyme activities of grafted and self-rooted eggplants under the stress of different frequencies carbendazim application. After applying carbendazim for once, twice, and three times, the fruits’ pesticide residue of grafted eggplants decreased by 12.7%-49.6%, 11.4%-63.1%, and 13.5%-44.1%, respectively, as compared with that of self-rooted eggplants. The plant height, stem diameter, and plant and fruit fresh weights of grafted eggplants were obviously higher than those of self-rooted eggplants, and the root activity of grafted eggplants after applying carbendazim for once, twice, and three times increased by 6.8%-29.3%, 8.7%-24.5%, and 11.1%-28.6%, respectively. The leaf catalase (CAT), peroxidase (POD), and glutathione peroxidase (GSH-PX) activities of grafted eggplants were higher than those of self-rooted plants, and the leaf relative conductivity and malondialdehyde (MDA) content of grafted eggplants after applying carbendazim for once, twice, and three times decreased by 16.3%-27.3%, 19.7%-31.9% and 20.5%-36.1%, and 21.4%-31.6%, 24.6%-37.9% and 23.7%-39.0%, respectively, as compared with those of self-rooted eggplants. These results showed that there was an obvious change in the test indicators after applying carbendazim for twice and three times, as compared with that after applying carbendazim for once. Under the stress of carbendazim, grafted eggplants had little fruits’ pesticide residue, apparently enhanced plant growth, and significantly improved metabolic activities of related enzymes, and thereby, mitigated the harmful effect of carbendazim stress on eggplant.

Effects of exogenous methyl jasmonate and insect injury-induced cotton plants on  selection behaviors of Aphis gossypii and its natural enemies. 

FENG Hong-zu, YAO Yong-sheng, WANG Lan**

2012, 31(10):  2555-2560. 

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By using Y-tube olfactometer, this paper studied the behavioral responses of cotton aphid (Aphis gossypii) and its two natural enemies Coccinella undecimpanctata and Chrysopa phyllochroma to different odor sources. No significant difference was observed in the attraction of healthy cotton leaves and the leaves injured by insects or treated with methyl jasmonate (MeJA) to cotton aphids. The selection of C. undecimpanctata and C. phyllochroma to the injured leaves was 2.7 and 2.2fold of that to the healthy leaves, respectively, with significant differences (P<0.001) among them. The selection of C. undecimpanctata and C. phyllochroma to the leaves treated with MeJA was significantly higher than that to the healthy leaves (P<0.01). The leaves treated with 0.02 μmol·mL^-1 of MeJA showed the strongest attraction to natural enemies. Even the leaves treated with MeJA alone also had the attraction to C. undecimpanctata and C. phyllochroma. This study would provide a theoretical basis for the chemical ecological regulation of cotton aphid.

Effects of cycocel on the dwarfing characteristics and physiological indices of Vallisneria natans.

LIU Xiao-pei1, ZHANG Yin-jiang1,2**, LI Yan1, DONG Yue1, WEN Xiao-feng1, YI Mian1, HE Pei-min1,2, LI Juan-ying1,2

2012, 31(10):  2561-2567. 

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More and more attention has being paid to the  pollution in waters induced by the fast growth of submerged macrophyte. In this paper, a laboratory simulation experiment was conducted to study the effects of different concentrations (0, 0.01, 0.02, 0.10, 0.20, 0.50, 0.75, 1.00, and 1.25 g·L^-1) of cycocel on the dwarfing characteristics and physiological indices of Vallisneria natans. After treated with different concentration cycocel for 30 days, the plant height of V. natans had significant differences (P<0.05). The higher the cycocel concentration, the higher the dwarfing effect was. Cycocel made V. natans leaves wider and its roots shorter. At 0.02-0.20 g·L^-1 of cycocel, the root/shoot ratio increased; at 0.01-0.50 g·L^-1 of cycocel, the plant number increased. At 0.10-0.50 g·L^-1 of cycocel, the wet weight of V. natans increased by 61%-123%, which meant that the plants could absorb more nutrients such as nitrogen and phosphorus from waters and sediments, and improve water quality. At 0.02 g·L^-1 of cycocel, the dwarfing effect was much better, and the plants occupied smaller space. Moreover, the plants at 0.02 g·L^-1 of cycocel had longer root length and higher root/shoot ratio, chlorophyll content,  SOD and POD activities,  accordingly, had an increased stressresistance and a delayed aging. In sum, 0.02 g·L^-1 of cycocel was more suitable for V. natans dwarfing.

Habitat suitability assessment of Mongolian gazelle around Dalai Lake area in Inner Mongolia.

LIU Bing-wan1**, GU Li1, ZHANG Bo1, QIN Li-xin1, BAO Li-ming2

2012, 31(10):  2568-2572. 

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Based on the survey of Mongolian gazelle (Procapra gutturosa) habitats around the Dalai Lake area of Inner Mongolia in 2008, the vegetation type, vegetation coverage, slope, distance from water, distance to grazing point, distance to residential area, and distance to road were selected as the factors for the assessment of habitat suitability, and the 3S technique and fuzzy evaluation were adopted to assess the habitat suitability of the Mongolian gazelle around the Dalai Lake area. Without considering human disturbance, the most suitable, less suitable, and unsuitable habitat areas for Mongolian gazelle were 17.7%, 36.9%, and 45.4% of the total, respectively; with the consideration of human disturbances, the most suitable, less suitable, and unsuitable habitat areas for Mongolian gazelle reduced to 13.0%, 28.3%, and 58.7% of the total, respectively. The comparison of the actual and potential habitats of the Mongolian gazelle showed that the unsuitable habitat area was increased by 29.2%, suggesting that human disturbance could be the main cause of the sharp decrease of suitable habitat for Mongolian gazelle around the Dalai Lake area of Inner Mongolia.  

Effects of Pinus tabuliformis needles from different stand types on the growth and development of Dendrolimus tabulaeformis with two differentcolored morphs.

CHEN Chen1, ZHOU Guo-na1, LIU Qiao-hong1, GAO Bao-jia1,2**

2012, 31(10):  2573-2578. 

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A laboratory experiment was conducted to study the effects of breeding with the Pinus tabuliformis needles from different stand types on the growth and development of Dendrolimus tabulaeformis with differentcolored morphs. Compared with yellow morph larvae, black morph larvae had the characteristics of fast body weight growth, heavier female pupa, larger fertility, and higher survival rate. Breeding with the P. tabuliformis needles from mixed stand prolonged the larvae development duration and restrained the larvae growth and development, as compared to the breeding with the needles from pure stand. It was suggested that the P. tabuliformis needles from mixed stand could contain unfavorable substances for the development of D. tabulaeformis larvae.

Diversity of butterfly in different habitat types in rapid urbanization area.

LIN Fang-miao1,2, YUAN Xing-zhong1,3**, WU Yu-yuan1,2, LIU Hong1

2012, 31(10):  2579-2584. 

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From May to October 2011, an investigation was made on the butterfly diversity in the artificial secondary forest, artificial grassland, nursery land, waste grassland, cropland, and natural secondary forest in Liangjiang New District of Chongqing City, Southwest China. A total of 1547 butterflies were collected, belonging to 37 species, 27 genera, and 6 families, among which, Pieris rapae, Pieris canidia, Pseudozizeeria maha, and Tongeia filicaudis were the dominant species. The butterfly diversity index varied obviously along a gradient of urbanization, i.e., the higher level the urbanization, the lower the butterfly diversity index. Habitat type and human disturbance had remarkable effects on the butterfly diversity, and the latter could be used as an effective indicator of habitat quality and environmental change. It was suggested that in rapid urbanization area, different measures should be taken to conserve and enhance the biodiversity, based on the urbanization level and habitat type.

Genetic diversity of six mud crab (Scylla paramamosain) populations in Beibu Gulf of South China based on ISSR analysis.

SONG Zhong-kui1, 2**, SUN Feng-yu1, 3, LI Meng-yun1, 4, ZHAO Peng1, NIE Zhen-ping1, SU Qiong1

2012, 31(10):  2585-2590. 

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ISSR-PCR technique was adopted to investigate the genetic variation and genetic structure of six Scylla paramamosain geographic populations (QH, DJ, QZW, LSW, ZZW, and ZK) in the Beibu Gulf of South China. A total of 111 individuals were amplified by 8 ISSR primers, and 66 valid loci were analyzed, of which, 56 loci were polymorphic. The percentage of polymorphic loci (PPL) was 84.85% at species level. The PPL of the six populations ranged from 51.52% to 63.64%, with an average of 57.58%. The genetic diversity of the six populations decreased in the order of QH > DJ >QZW> LSW >ZZW >ZK. The PPL and the Shannon′s information index at species or population level showed that the genetic diversity of S. paramamosain arrived at a higher level within the crustacean, but was still lower than that of the other several marine animals of economic importance. The total coefficient of genetic differentiation (G_ST=0.1841) showed that most of the total genetic variation variance (81.59%) indwelled within populations, suggesting a higher level of genetic differentiation among the populations. However, the coefficient of genetic differentiation (G_ST=0.0689-0.1276) of pairwise populations suggested the mediumdegree genetic differentiation among the populations. The analysis of molecular variance (AMOVA) showed that the genetic variation variance within and among the populations accounted for 87.03% and 12.97%, respectively, suggesting that the genetic differentiation among the populations was at a medium level, but the differentiation was significant (P<0.001). The Mantel test suggested that there was no significant correlation between the genetic distance and geographic distance of the six S. paramamosain populations. Clustering analysis showed that the four populations from Guangxi coastal areas could be clustered into a clade.

Community structure and diversity of demersal fish in the middle reaches of Heilongjiang River, Northeast China.

HUO Tang-bin1,2**, JIANG Zuo-fa1, MA Bo1, LI Zhe1, YU Hong-xian2

2012, 31(10):  2591-2598. 

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By using fixing nets and hanging nets, an investigation was conducted on the demersal fish in the middle reaches of Heilongjiang River from 2010 to 2011. A total of 47 demersal fish species were recorded, belonging to 33 genera, 12 families, and 7 orders, among which, Rutilus rutilus lacustris (Pallas) was adventive, and Acipenser schenckii (Brandt), Huso dauricus (Georgi), Lampetra japonica (Martens), and L. reissneri (Dybowski) were the fish species listed in the China Red Data Book of Endangered Animals (Pisces). Cypriniformes had the most abundant species (31), accounting for 65.96% of the total. The average density and biomass of the demersal fish were 139.00 ind·m^-3 and 344.58 g·m^-3, respectively. Fluviolacustrine species and heterophagous species were the main ecological groups, and Acheilognathus chankaensis (Dybowski), Pelteobagrus nitidus (Sauvage et Dabry), Pseudorasbora parva (Temminck et Schlegel), Leiocassis argentivittatus (Regan), and Xenocypris argentea (Gunther) were the dominant community species. The body weight of the dominant species except Silurus asotus (Linnaeus) was less than 30 g. The Margalef richness index D, Shannon diversity index H′, and Pielou evenness index J′ of the demersal fish in each section of Heilongjiang River were all lower, but had definite differences. The water quality in the middle reaches of Heilongjiang River was high, and surpassed the II class water quality during most of time. No significant relationships were observed between the fish diversity index and the environmental factors including nutrients and transparency in the River, but a positive relationship was found between the H′ and the water NH₄⁺-N and total N.

Community structure and dynamic distribution pattern of waterbird in Shanghai.

PEI En-le1**, YUAN Xiao1, TANG Chen-dong2, CAI Yin-ting3, WU Di1

2012, 31(10):  2599-2605. 

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From 2006 to 2010, an investigation was conducted synchronously at nine important sites of Shanghai to understand the inhabited status and population dynamics of waterbird. In the study period, a total of 796738 waterbird individuals belonging to 133 species of 18 families and 9 orders were recorded, among which, there were 53 species of Charadriiformes, 28 species of Anseriformes, 17 species of Ciconiiformes, and 16 species of Lariformes. According to resident type, the residents, summer breeders, winter migrants, and traveling birds occupied 3.0%, 9.0%, 43.6%, and 44.4% of the total species number, respectively. The migration period of winter migrants with Anatidae as the priority was from September to next April, and the traveling birds with Charadriiformes as the priority were generally migrated northward from March to May (spring) and southward from August to October (autumn). The habitats with more quantities of waterbird were in the order of Chongming Dongtan Nature Reserve, Nanhui Dongtan, and Jiuduansha Nature Reserve. Clustering and habitat preference analyses showed that goose and duck (Anatidae) preferred to the mudflats with shallow water and the open and large water areas, while shorebirds (Charadriiformes) preferred to the larger areas coastal mudflats. Mudflat reclamation and human disturbance were the important factors negatively affecting the waterbird community, and accordingly, some recommendations for waterbird habitat management were put forward.

Swimming performance and energy metabolism of male and female crucian carps (Carassius auratus) during their Ⅲ reproduction phase.

YANG Han, CAO Zhen-dong**, FU Shi-jian

2012, 31(10):  2606-2612. 

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To examine whether the swimming performance and metabolic traits of 1-year-old male and female crucian carps (Carassius auratus) during their Ⅲ reproduction phase have differences, the fast-start movement, critical swimming speed (U_crit), rest metabolic rate (MO_2rest), active metabolic rate (MO_2active), and metabolic rate (MO₂) during different swimming speeds were measured at water temperature 20±1 ℃. The U_crit of female and male crucian carps was 6.97±0.22 and 7.29±0.31 BL·s^-1, and the maximum linear velocity during fast-start movement (V_max) was 20.48±0.69 and 20.40±1.09 BL·s^-1, respectively, with no significant differences. The U_crit, V_max, maximum linear acceleration during fast-start movement (a_max), reaction time, migration distance during the first 120 ms of faststart movement, and MO_2rest of female and male crucian carps also had no significant differences. However, the MO_2active and metabolic scope of female crucian carps were significantly higher than those of the males (341.92±22.59 vs. 307.50±22.66 mg O₂·kg^-1·h^-1 and 257.18±18.51 vs. 220.20±18.95 mg O₂·kg^-1·h^-1, respectively). It was suggested that the male and female crucian carps during their Ⅲ reproduction phase had no significant difference in the swimming capacity, but the females adopted metabolic up-regulation strategy as a compensation for their increased energy burden due to reproduction status.

Effects of water and sediment regulation at Xiaolangdi Dam on the fish assemblages from Hukou to Sanmenxia section of Yellow River.

ZHANG Jun-yan, ZHANG Jian-jun**, SHEN Hong-bao, LU Bin-bin, WANG Xiao-chen, XING Juan-juan

2012, 31(10):  2613-2618. 

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In order to understand the effects of water and sediment regulation at Xiaolangdi Dam on the fish assemblages in the midstream of Yellow River, an investigation was conducted on the fish resources from Hukou to Sanmenxia section of Yellow River during the period from June to July, 2011. Twenty six and thirty five species of fish composition were observed before and after the water and sediment regulation, respectively. After the water and sediment regulation, both the fish composition and the fish captured in Sanmenxia Reservoir declined, and the smallsized fish community, e.g., Hemiculter leucisculus, dominated. The fish kinds and catches in the section from Hukou to Tonguan after the water and sediment regulation had somewhat increase, but the smallsized fish community still occupied the main position. The adult fish resources from Hukou to Sanmenxia section reduced significantly. The analysis of the fish diversity before and after the water and sediment regulation showed that in Sanmenxia Reservoir, the Margalef richness index, Shannon diversity index, and Pielou evenness index of fish resources all changed obviously. Some advices were given in the protection of migratory fish stocks in the middle reaches of Yellow River.

Effects of salinity stress on the adjustment of branchial chloride cells in Oreochromis niloticus.

ZHUANG Qing-qing, ZHAO Jin-liang**, ZHAO Li-hui, CHANG Jian-ju

2012, 31(10):  2619-2624. 

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By the methods of scanning electron micrograph and immunohistochemistry, this paper studied the distribution of epithelial chloride cells (CC) in Nile tilapia (Oreochromis niloticus) gills and the effects of different salinity (0, 10, 20, and 30) stress on the CC number and morphology. The surface scanning of the gills showed the epithelial chloride cells were distributed close to the interlamellar regions of gill filaments. According to the apical size, the CC could be divided into three subtypes, i.e., subtype Ⅰ (>6.5 μm), subtype Ⅱ (3.2-6.5 μm), and subtype Ⅲ (<3.2 μm). The CC number in the gills at different salinities was in the sequence of salinity 10 < salinity 20 < salinity 0 < salinity 30. When the Nile tilapia transferred to the waters from salinity 0 to salinity 10, the total number of the CC in gills decreased, mainly due to the significant decrease of the subtype Ⅰ cells. The CC number at salinity 20 was higher than that at salinity 10, but the difference was not significant. The CC number at salinity 30 increased significantly with the increase of subtype Ⅲ cells. Immunohistochemical staining further confirmed that at different salinities, the Na⁺-K⁺-ATPase immunoreactive (NKA-IR) cells were all distributed in the interlamellar region of the gill filaments. It was suggested that Nile tilapia could adapt to the salinity change of the environment through changing the quantity and morphological structure of branchial chloride cells, and the subtypes Ⅰ and Ⅲ cells could play a key role for the osmoregulation in the waters with low and high salinity, respectively.

Effects of water salinity on the antioxidant enzyme activities and growth of clam Cyclina sinensis. 

LI Zi-niu, LIN Ting-ting, YAO Zong-li, LAI Qi-fang, LU Jian-xue, WANG Hui, ZHOU Kai**

2012, 31(10):  2625-2630. 

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In order to clarify the effects of water salinity on the growth and immune enzymes of clam Cyclina sinensis, and accordingly, to explore the possibility of breeding C. sinensis in different salinity environment, the individuals of the clam were undergone different salinity stress (10, 15, 25 (control), and 35), with the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in gill, mantle, and hepatopancreas at 0, 3, 6, 12, 24, 48, and 96 h of salinity stress measured respectively. The monthly length and weight gain rates were also measured after the individuals cultured under different salinity stress for two months. In different tissues of the clam, hepatopancreas had the highest antioxidant enzyme activities, followed by mantle, and gill. For the individuals under salinity 10, the SOD activity in gill at 3 h and in mantle and hepatopancreas at 3, 6, 12, and 24 h, as well as the CAT activity in mantle at 6 and 12 h and in hepatopancreas at 3 and 6 h, was significantly higher than that of the control (P <0.05); for the individuals under salinity 15, only the SOD and CAT activities in hepatopancreas at 3 h were significantly higher than those of the control (P<0.05); whereas for the individuals under  salinity 35, the SOD activity in gill at 3 and 6 h, in mantle at 3, 6, 12, and 24 h, and in hepatopancreas at 0, 3, 6, 12, 24, 48, and 96 h, as well as the CAT activity in gill at 3 h, in mantle at 3, 6, 12, and 24 h, and in hepatopancreas at 3, 6, 24, 48, and 96 h, was significantly higher than that of the control (P <0.05). In addition, the variation extents of the SOD and CAT activities under salinity 35 were significantly higher than those under salinity 10 (P<0.05). The length and weight gain rates of the individuals under salinity 15 were greater, but had no significant differences with the control, and also, had no differences between the first month and the second month (P>0.05). Under salinity 10, the length and weight gain rates were significantly lower than those under salinity 15 and of the control, and had significant differences between the first and second months (P<0.05). Under salinity 35, both the length gain rate and the weight gain rate were the lowest, and had no significant differences between the first and second months. In conclusion, when stressed by salinity, the C. sinensis should take about 24 h for the restoration of its antioxidant enzyme activities. C. sinensis had a stronger tolerance against low salinity than against high salinity. When the salinity was at 35, the antioxidant enzyme activities of the clam varied greatly, and the growth was almost stopped.

Flocculating effect of three kinds of flocculants on Isochrysis galbana.

GAO Wei, LI Qian, LI Lin, JIA Xing-jun, CUI Zhi-song, ZHOU Wen-jun, ZHENG Li**

2012, 31(10):  2631-2634. 

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Aimed to investigate the flocculating effect and impairment of three kinds of flocculants on Isochrysis galbana, spectrophotometry and gravimetric method were adopted to determine the flocculating rate, and morphological observation and total ester measurement were made to evaluate the flocculating impairment on algae cell. The results showed that ferric chloride and alum showed higher flocculating velocity (less than 4 hours). For flocculating >90% of algae cells, a dose of ≥20 mg·L^-1 of ferric chloride or at least 80 mg·L^-1 of alum was required. At a dose of 80 mg·L^-1 of alum, the algal total lipid productivity was the highest (29.9%), while the impairment on the cell integrity was the least, suggesting that 80 mg·L^-1 of alum could be used as the flocculant to harvest I. galbana for biofuel production.

Spatial difference of precipitation variation in Three-River headwaters region of China in recent 51 years.

LI Shan-shan, ZHANG Ming-jun**, WANG Bao-long, LI Xiao-fei, LUO Shu-fei

2012, 31(10):  2635-2643. 

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Based on the 1960-2010 precipitation data from 12 meteorological stations in the Three-River headwaters region, and by the methods of climatic linear regression, 5-year moving average, inverse distance weighted (IDW) interpolation, Morlet wavelet analysis, and rescaled range analysis, this paper analyzed the spatiotemporal variations of precipitation and its future tendency in this region. In 1960-2010, the annual precipitation in this region presented an overall increasing trend, being lower in the 1960s, 1970s, and 1990s, obviously higher in the 1980s, and markedly increased after 2000. The precipitation in spring, summer, and winter, especially in spring, exhibited an increasing trend, but that in autumn had a decreasing trend. The variation trend of the precipitation in different catchments was not the same in four seasons. In most areas of this region, the precipitation had an increasing trend, being higher in the north and lower in the south, but less difference in the east and west. The precipitation in different catchments had different vibration periods during a certain time series. A similar variation trend was observed in the annual and seasonal precipitation in the region between the past and the future, but the continual strength of the precipitation somewhat differed with the catchments.

Interregional conflicts in water resources utilization during Beijing urbanization.

YANG Pei-guo1**, WU Shao-hong2, HU Jun-feng1, LI Jing3, PAN Tao2, YU Bo-hua2

2012, 31(10):  2644-2650. 

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With rapid urbanization, Beijing needs more and more water with high quality, which inevitably reduces the water amount in the upper reaches of the whole watershed. Meanwhile, it requires the upper reaches to adopt various measures, including limiting industry development, to protect water quality, which in a certain degree restricts the economic development and life quality improvement in the upper reaches, resulting in the interregional conflicts in water resources utilization between the upper reaches and the lower reaches. Based on the analysis of the imbalance between the water supply and demand in Beijing, this paper discussed the interregional conflicts of the watershed water resources utilization on the basis of water quality protection and water demand increase. It was considered that the inadequate total water resources, unclear ownership, and having not fully implement interregional compensation mechanism could be the main causes for the interregional conflicts of water resources utilization. To solve this problem, four measures should be adopted, i.e., coordinating the economic benefits among different regions and establishing eco-compensation and cooperation mechanism, applying right water allocation institution, implementing unified management of basin water resources, and accelerating the construction and utilization of huge project to transfer water to Beijing.

Ecological importance zoning and its spatial overlay relationships with construction lands in Xijiang River Economic Belt of Guangxi, South China.

LI Ping-xing**

2012, 31(10):  2651-2656. 

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The evaluation of ecological importance is an effective way to identify the important ecological function areas and to optimize the regional spatial development pattern. In this paper, a model for evaluating the ecological importance by integrating the suitability of ecological factors and the importance of ecological locations was proposed, and, taking the Xijiang River Economic Belt of Guangxi as a case, the spatial zoning of ecological importance and its spatial overlay relationships with the distributions of current construction lands were studied. In the Belt, the zones with extremely important, very important, important, general, and unimportant ecological importance accounted for 16%, 36%, 17%, 15% and 16% of the whole area, respectively. The western part of the Belt had a relatively high importance, followed by the eastern part, while the central part had the least one. The existed construction lands in cities and towns and the rural lands were mainly located at unimportant, important, and very important zones, whereas the industrial and mining lands were in relatively dispersed distribution. To a certain extent, a selective and oriented ecological spatial occupation based on the evaluation of ecological importance could alleviate the ecoenvironmental pressure induced by regional industrialization and urbanization, and thus, realize regional sustainable development.

Availability of arsenic in paddy and vegetable soils in Shuikoushan mining area of Hunan Province, South-central China.

ZHU Yan-ming1,2, FENG Ren-wei3, WEI Chao-yang1**

2012, 31(10):  2657-2661. 

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Soil samples were collected from the surrounding areas of Shuikoushan mining area in Hunan Province of South-central China to determine the soil total and available arsenic contents and the soil physical and chemical properties (pH value, organic matter content, and clay content), with the differences of the test parameters in two agricultural soils (vegetable soil and paddy soil) and the relationships between the soil available arsenic content and the soil physical and chemical properties analyzed. The average content of the arsenic in paddy soil and vegetable soil was 72.01 and 30.71 mg·kg^-1, respectively, being close to or exceeding the National Soil Environmental Quality Standard Ⅱ. There existed significant differences in the soil physical and chemical properties between the two agricultural soils, with the higher contents of clay and organic matter but lower pH value in paddy soil than those in vegetable soil, and the paddy soil being obviously acidified. The total arsenic content in vegetable soil was far higher than that in paddy soil, but the available arsenic content of the two soils had less difference. Except for total arsenic, the available arsenic content in paddy soil was significantly positively correlated with organic matter content, and that in vegetable soil was significantly positively correlated with pH value. In the Shuikoushan mining area, vegetable soil had a higher risk of arsenic pollution than paddy soil, and thus, necessary remediation strategies or adjustment of land use pattern should be
adopted to reduce the health risk of soil arsenic contamination.

Plant physiological mechanisms in adapting to waterlogging stress: A review.

PAN Lan, XUE Li**

2012, 31(10):  2662-2672. 

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Waterlogging stress causes low light condition, and makes gas diffusion limited, plant leaf membrane lipid peroxidation induced, endogenous protective enzyme system damaged, chlorophyll degraded, MDA accumulation promoted, and photosynthetic rate declined. To adapt to waterlogging, plants develop a series of effective physiological and biochemical mechanisms to keep normal life activity, e.g., maintaining the balance of cell osmotic potential via regulating osmolyte contents, increasing intracellular antioxidant enzyme activities to remove free radicals and to prevent or reduce cell injury, and changing metabolic paths and regulating hormones to maintain energy reserves and lower rate metabolism. This paper summarized the research advances in the impacts of waterlogging stress on plant cell membrane system and its function, photosynthesis, respiration, hormones, physiological metabolism, and gene regulation, as well as the changes of plant ecological and physiological characteristics after waterlogging, and revealed the adaptation mechanisms of plants to waterlogging stress. It was suggested that to study the molecular mechanisms of plants in response to waterlogging and the effects of environmental factors on submerged plants and to make site-specific observations on the waterlogging stress on forests would be the important research aspects in the future.

Estimation methods of wetland ecosystem carbon storage: A review.

CUI Li-juan**, MA Qiong-fang, SONG Hong-tao, LUAN Jun-wei

2012, 31(10):  2673-2680. 

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To estimate the carbon storage in wetland ecosystem is a difficulty in wetland research. The current methods can only roughly estimate but cannot accurately calculate the wetland ecosystem carbon storage. This paper reviewed the methods for estimating the carbon storages in various components of wetland ecosystem, and indicated that the estimation of wetland ecosystem carbon storage should be fully integrated the estimation methods of carbon storage in both aquatic and terrestrial components. The factors affecting the precision of wetland ecosystem carbon storage estimation were summarized, and it was considered that wetland area, carbon density, and depths of water, soil and sediment could be the main factors affecting the precision of wetland carbon storage estimation at regional scale.

Organic carbon in mangrove wetlands: A review.

ZHU Yao-jun, GUO Ju-lan, WU Gao-jie

2012, 31(10):  2681-2687. 

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Mangrove wetland is one of the most productive ecosystems in the world. Its occupied area is not vast, but its carbonsequestration capability per unit area is quite strong, being an important ‘blue carbon’ sink, and the storage and dynamics of the organic carbon in the sink having great effects on the balance of global carbon cycle. In this paper, the present research progress on the organic carbon storage (including that of vegetation biomass and sediment) in mangrove wetlands and related measurement methods, the components and source of the sediment organic carbon, and the factors affecting the dynamics of the organic carbon in mangrove wetlands were summarized, and the existing problems and future research trends were analyzed. In terms of the rapid decline of the carbonsequestration capability of mangrove wetland and the rapid decrease of the wetland resource, it would be necessary to accurately assess the carbon sink and its dynamics of mangrove forests, which would contribute to the carbon measurement and valuation of coastal wetlands under the treaty of climate change framework, help to reveal the feedback relationships of mangrove ecosystem and global change, and provide a basis for the restoration and protection of mangrove ecosystems.

Rhizosphere soil fauna and its effects on plant growth: A review. 

ZHU Yong-heng1,2**, LI Ke-zhong1,2, LU Lin1

2012, 31(10):  2688-2693. 

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Rhizosphere soil fauna is an important component of soil organisms, playing active roles in the transformation, storage and release of nutrients, the regulation of soil microbes, and the changes of soil physical and chemical properties, and finally, affecting the plant growth and its productivity. This paper reviewed the roles of soil fauna in rhizosphere soil ecosystem, the interactions between rhizosphere soil fauna and microbes, and the effects of rhizosphere soil fauna on plant growth, and approached the problems to be urgently solved in the researches of rhizosphere soil fauna and its effects on plant growth. The future related research directions needed to be strengthened were proposed as well.

Assessment of eco-environmental impacts of linear project construction: Research progress and perspectives.

XIAO jun1,2, WANG Ya-feng1, CHEN Li-ding1**

2012, 31(10):  2694-2702. 

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Linear project construction is very common in construction projects. It plays an important role in accelerating socio-economic development and improving living standard, but brings about a series of ecological and environmental problems. Therefore, assessing the eco-environmental impacts of linear project construction is of great practical significance. This paper summarized the main types of linear project construction and their ecological and environmental impacts, analyzed the importance of eco-environmental assessment of linear project construction, and introduced the applications and related researches of eco-environmental assessment in linear project constructions. The prominent problems in current related studies were discussed, and the future research directions were suggested. It was considered that, to integrate the geographic information system and the remote sensing and modelling simulating techniques, to improve evaluation methods through establishing more quantitative and accurate assessment systems, to achieve the indices systematization while paying attention to the scale effect of assessment scope, and thus, to make the eco-environmental impact assessment more scientific and credible would be the development directions for the eco-environment assessment of linear project construction.

Simulation and prediction of urban spatial expansion in Shanghai: A comparison of multiple models.

CUI Fu-quan1, XU Xin-liang2**, SUN Xi-hua1

2012, 31(10):  2703-2708. 

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Using models is an effective way to simulate and predict the spatiotemporal process of urban expansion. In this paper, the CLUE-S, LTM, and SLEUTH models were used, and combined with GIS technology, to simulate and predict the urban expansion process of Shanghai, with the results compared and analyzed. It was shown that the three models had somewhat different mechanisms in the simulation and prediction. CLUE-S and LTM models predicted the urban expansion demand first, and then, through comprehensively analyzing different affecting factors, calculated the probability of urban expansion to achieve the spatial allocation, whereas SLEUTH model did the simulation and prediction directly, based on the analysis of the historical development of urban expansion. The three models simulation results of the urban expansion in Shanghai in 2005 were highly consistent with the remote sensing monitoring results. SLEUTH model had the highest simulation precision, with the Kappa coefficient being 0.85, suggesting that this model was superior to CLUE-S and LTM models. In 2005-2020, the area of urban expansion in Shanghai would be 207.7-320.87 km², and in 2020, the City’s area would be 1121.96-1235.13 km². In the next 15 years, the urban expansion rate of the City would be 13.85-21.39 km²·a^-1. Each of CLUE-S, LTM and SLEUTH models had its advantages and disadvantages, and to integrate the advantages of the three models and develop an open and comprehensive model would be the tendency of simulating and predicting urban expansion.