Table of Content

18 November 2012, Volume 23 Issue 11

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Articles

Litterfall amount and its dynamics in urban forest of Shenyang, Northeast China.

XU Wen-duo, CHEN Wei, HE Xing-yuan, XU Sheng, ZHANG Yue, WEN Hua

2012, 23(11):  2931-2939. 

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Twenty sampling sites were set in the urban forest of Shenyang to continuously observe the amount of forest litterfall and its dynamics in 2005-2007. During the three years, the leaf litters collected in twenty 1 m² litterfall traps were of 30 tree species, which accounted for 15.5% of the entire tree species in Shenyang, but the individual number and leaf area of the populations accounted for 63.8% and 69.9%, respectively. A significant positive correlation was observed between the leaf litterfall amount and the leaf area of the corresponding tree species, and there was a great difference in the beginning time of the leaf fall between different tree species. The species with earlier beginning time of leaf fall finished their leaf fall earlier, and thus, there was a significant positive correlation between the beginning time of leaf fall and the ending time and duration of leaf fall. The average annual litter production was 4229.0 kg·hm^-2, among which, leaf litterfall was 3397.36 kg·hm^-2, branch litterfall was 463.89 kg·hm^-2, and fruit and flower litterfall was 367.73 kg·hm^-2, accounting for 80.3%, 11.0%, and 8.7% of the total production, respectively. The seasonal dynamics of the litterfalls showed a single peak, with the maximum appeared in October and accounted for about 50.0% of the total. The large amount of the litterfalls could supply nutrients and energy for urban forest.

Effects of gap size on seedling natural regeneration in artificial Pinus tabulaeformis plantation.

HAN Wen-juan1, YUAN Xiao-qing2, ZHANG Wen-hui1

2012, 23(11):  2940-2948. 

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To clarify the effects of gap size created by thinning on the seedling natural regeneration in artificial Pinus tabulaeformis plantation, a
 plot investigation was conducted to study the ecological factors and the age structure, height, diameter, length of needles, and dry biomass of roots, stems, and needles of 1-10 year-old seedlings in different habitats, and a path analysis was made on the environmental factors affecting the seedling regeneration. Obvious differences were observed in the ecological factors in different size gaps and slope aspects. There lacked of above 3 year-old seedlings in understory and of above 7 year-old seedlings in small gap, and the seedlings of 5 and 6 yearold were lesser in big gap. The 1-10 year-old seedlings could be divided into 3 development phases, i.e., 1-3 year-old, 4-7 year-old, and 8-10 year-old seedlings, among which, 1-3 year-old seedlings were critical for the establishment and growth of the population. The growth situation of the seedlings in different habitats was in order of big gap in shady slope > big gap in sunny slope > small gap in sunny slope > small gap in shady slope > understory in sunny slope > understory in shady slope. Path analysis showed light intensity had decisive positive effects on the seedling number of different development phases, shrub coverage had decisive negative effects on the seedling number of 4-7 year-old and 8-10 year-old phases, whereas humus dry mass had negative effects on the seedling number of 4-7 year-old but positive effects on the seedling number of 8-10 yearold. It was suggested that in the management of artificial P. tabulaeformis plantation, relatively high intensity thinning combined with shrub clearing should be adopted to provide favorable conditions for the sustainable development of P. tabulaeformis population.

Effects of waternitrogen coupling on leaf nutrient contents of triploid Populus tomentosa clone BT17.

LUO Pan-pan, NIE Li-shui, XIN Ying, SUN Zhao-di, REN Zhong-xiu, WEI Dan

2012, 23(11):  2949-2954. 

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To understand the coupling effect of water and nitrogen on the leaf nutrient contents of Populus tomentosa and to search for an optimal combination of water and nitrogen for P. tomentosa, a field experiment with randomized block design (3 levels of irrigation water and 4 levels of fertilizer nitrogen) was conducted in a two-year-old P. tomentosa clone BT17 plantation in the nursery of Weixian County, Hebei Province of North China from 2007 to 2009. The N, P and K contents in BT17 leaves differed significantly among seasons, with the order of spring > summer > autumn, and had  significant differences among the 12 treatments, being the highest in the treatment 75% of field capacity and 160 g per plant of N application rate. The coupling of water and nitrogen had positive effects on the leaf N, P, and K contents, and thus, more attention should be paid to this coupling effect in the management of P. tomentosa. The leaf nutrient contents had different responses to water and nitrogen. The leaf N and K contents were more affected by soil water content, while the leaf P content was more affected by N application rate.

Variations of ground vegetation and soil properties during the growth process of artificial sandfixing Caragana intermedia plantations in desert steppe.

LIU Ren-tao, CHAI Yong-qing, XU Kun, ZHU Fan

2012, 23(11):  2955-2960. 

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To study the variation characteristics of ground vegetation and soil properties during the growth process of Caragana intermedia plantations in desert steppe is of scientific significance in revealing the ecological effect of the plantations on the restoration of desertified grassland ecosystem. In this paper, an investigation was conducted on the ground vegetation and soil properties in 6-, 15-, 24-, and 36-yr artificial sandfixing C. intermedia plantations in desert steppe of Ningxia, Northwest China, with the variation characteristics of the ground vegetation and soil properties during the growth process of the C. intermedia plantations analyzed. With the growth and development of the plantations, the shrub crown width, height, sprout number, and basal diameter all increased significantly, the contents of soil coarse sand and fine sand had significant decrease while those of very fine sand and clay silt were in adverse, the soil organic carbon, total N, and total P contents increased linearly, and the soil pH decreased significantly. During the growth process of the plantations, the species number and individual number of ground vegetation increased significantly, and the vegetation coverage and height presented the order of 24- > 15- > 6- > 36-yr plantation. The soil texture, bulk density, nutrient contents, and pH value were the main factors affecting the species and individual number as well as the coverage of ground vegetation in C. intermedia plantations. It was suggested that in desert steppe, the growth process of artificial sandfixing C. intermedia plantation benefited the improvement of soil conditions and the recovery of ground vegetation, and promoted the restoration of degraded grassland ecosystem in desert steppe.  

Changes of foliar δ¹³C value of Quercus fabric in different root underground habitat types in Karst area.

FU Yu-hong1,2, HUANG Zong-sheng1, YU Li-fei1

2012, 23(11):  2961-2967. 

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Selecting the dominant tree species Quercus fabric in three root underground habitat types (the dolomites of low oblique occurrence with multilayer space, middle oblique occurrence with multilayer space, and high oblique occurrence with multilayer space) in Karst area as test object, this paper studied the foliar δ¹³C value and its correlations with habitat soil conditions, and the plant water use efficiency. There existed remarkable differences in the foliar δ¹³C value of Q. fabric among the three habitat types, being decreased in the order of low oblique occurrence with multilayer space type (-26.35‰) > high oblique occurrence with multilayer space type (-26.66‰) > middle oblique occurrence with multilayer space type (-27.07‰). Accordingly, the plant water use efficiency decreased in the same order. The foliar δ¹³C value had significant correlation with habitat soil moisture content, but less correlation with habitat soil elements contents. The δ¹³C value increased with the decrease of soil moisture content and soil fertility.

Effects of treating with concentrated sulfuric acid on the seed germination of ten Hibiscus hamabo provenance families.

WANG Xiao-xue1,2, SUN Hai-jing1, LIU Yun2,CHEN Yi-tai1, FENG Da-lan3, LI Sha4

2012, 23(11):  2968-2974. 

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The seeds from ten Hibiscus hamabo provenance families were treated with concentrated sulfuric acid for different durations (0, 10,
15, and 20 min), and the seed germination rate, germination energy, and germination index, as well as the seed relative water adsorption rate, soluble sugar and starch contents, and α-amylase activity during the germination, were determined, aimed to study the effects of treating with concentrated sulfuric acid on the seed germination of H. hamabo and the differences of the seed germination among different H. hamabo provenance families. After treated with concentrated sulfuric acid, the seed germination rate, germination energy, and germination index increased significantly, and the germination time shortened remarkably. Treating with concentrated sulfuric acid for 15 minutes had the best effect, i.e., the germination rate, germination energy, and germination index were up to 95.7%, 91.3%, and 13.28, respectively, and the germination time was the shortest. The seed germination rate, germination energy, and germination index differed significantly with different provenance families, the highest germination index (15.13) being 2.12 times of the lowest germination index (7.15), and the highest germination energy (98.0%) being 1.77 times of the lowest one (55.5%). Treating with concentrated sulfuric acid accelerated the physiological and biochemical processes of seed germination, and the relative water absorption rate, soluble sugar content, and α-amylase activity were decreased after an initial increase, with the maximum at the early stage of germination. There was a significant negative relationship between the seed starch content and the seed germination index.

Canopy conductance characteristics of poplar in agroforestry system in west Liaoning Province of Northeast China.

LI Zheng1,2, NIU Li-hua1, YUAN Feng-hui1, GUAN De-xin1, WANG An-zhi1, JIN Chang-jie1, WU Jia-bing1

2012, 23(11):  2975-2982. 

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By using Granier’s thermal dissipation probe, the sap flow of poplar in a poplar-maize agroforestry system in west Liaoning was continuously measured, and as well, the environmental factors such as air temperature, air humidity, net radiation, wind speed, soil temperature, and soil moisture content were synchronically measured. Based on the sap flow data, the canopy conductance of poplar was calculated with simplified Penman-Monteith equation. In the study area, the diurnal variation of poplar’s canopy conductance showed a “single peak” curve, whereas the seasonal variation showed a decreasing trend. There was a negative logarithm relationship between the canopy conductance and vapor pressure deficit, with the sensitivity of canopy conductance to vapor pressure deficit change decreased gradually from May to September. The canopy conductance had a positive relationship with solar radiation. In different months, the correlation degree of canopy conductance with environmental factors differed. The vapor pressure deficit in the whole growth period of poplar was the most significant environmental factor correlated with the canopy conductance.

Genetic diversity and genetic differentiation of Rhododendron concinnum wild populations in Qinling Mountains of Northwest China: An AFLP analysis.

ZHAO Bing, XU Man, SI Guo-chen, LI Hou-hua， ZHANG Yan-long

2012, 23(11):  2983-2990. 

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By using amplified fragment length polymorphism (AFLP) technique, an investigation was made on the genetic diversity and genetic differentiation of seven wild populations of Rhododendron concinnum in Qinling Mountains of Northwest China．A total of 182 amplification products were generated from three AFLP selective primer combinations, of which, 151 were polymorphic．The percentage of polymorphism was 83.1%. The change trends showed by the percentage of polymorphic loci (PPL), Nei’s gene diversity (h), and Shannon’s information index (I) were uniform, and the order of the populations was Meixian > Zhashui > Zhen’an > Huxian > Ningqiang > Nanzheng > Zhouzhi. The POPGENE analysis showed that the R.concinnum had higher genetic diversity at both species level (PPL=91.22%，I=0.7217，h=0.5095) and population level (PPL=77.56%，I=0.6409，h=0.4725). The coefficient of gene differentiation among the populations (G_st) was 0.0726, indicating that 92.74% of genetic variation occurred within the populations. The analysis of molecular variance (AMOVA) showed that 85.3% of the genetic variation was within the populations, and 14.7% of it was among the populations. The unweighted pair group method with rithmeticmean (UPGMA) indicated that there was no significant correlation between the genetic distance and the geographic distance among the R. concinnum populations. The conservation strategies for R. concinnum germplasm resources were put forward.

Effects of grazing disturbance on leaf traits and their interrelationships of plants in desert steppe.

AN Hui

2012, 23(11):  2991-2996. 

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This paper studied the effects of grazing disturbance on the specific leaf area (SLA), leaf dry matter content (LDMC), leaf area, and leaf dry mass of dominant plant species Cynanchum komarovii, Euphorbia esula, Glycyrrhiza uralensis, and Lespedeza potaninii in desert steppe of Ningxia, Northwest China, aimed to approach the responses and adaptation strategies of different plant species in desert steppe to the environmental change. With the decrease of grazing intensity, the specific leaf area (SLA) of the four dominant species presented a decreasing trend. Under different grazing intensities, the SLA of the four dominant species had significant differences, while the LDMC didn’t. There existed definite differences in the interrelationships of leaf traits among different plant species. For C. komarovii and G. uralensis, there was a significant negative relationship between SLA and LDMC， for E. esula and L. potaninii, there was a positive relationship between the two parameters. The changes in the leaf traits in response to grazing intensity suggested that the SLA could be more sensitive to the environmental change than LDMC, and the SLA could be used as an indicator of resources use strategies of plants in desert steppe environments.

Reinvasion of exotic plant species Spartina alterniflora in Chongming Dongtan Nature Reserve of Shanghai.

XIAO De-rong1, ZHU Zhen-chang2, YUAN Lin2, TIAN Kun1

2012, 23(11):  2997-3002. 

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A demonstration plot in Chongming Dongtan for controlling exotic plant species Spartina alterniflora by using an integrated treatment technique of tussock cutting plus water level controlling was selected to make a 2-year monitoring on  the reinvasion process of this plant species. A large number of S. lterniflora seedlings could proliferate and settle down in the hydrological restoring plots by tidal water in spring, and, after two years, the reinvasion community was established, with no obvious differences in its density as compared to the communities in neighboring areas. However, the distance of extension via vegetative propagation was limited. At the plots maintaining waterlogging, the distance of 2-year lateral extension was less than 1 m; at physically isolated plots, there was no any reinvasion of S. alterniflora. The rapid spreading of the seedlings in spring was the key of the fast reinvasion of S. alterniflora, and thus, to completely eradicate the spreading source from neighboring areas, to build isolation barrier to stop the spreading of this plant, and to adopt biological substitute by planting a native species such as Phragmites australis would be the main countermeasures to effectively prevent the reinvasion of S. alterniflora.

Effects of exogenous nitric oxide on the growth and nitrogen metabolism of alfalfa seedlings under salt stress.

ZHOU Wan-hai1，2，3, SHI Shang-li1，2，3, KOU Jiang-tao1，2，3

2012, 23(11):  3003-3008. 

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In order to explore the regulation approaches for improving the salt-tolerance of alfalfa, the seedlings of Medicago sativa L. cv. Gannong No. 4 were taken to study their growth and nitrogen metabolism under salt stress as affected by NO-donor SNP, NO-scavenger c-PTIO, and sodium ferrocyanide (a SNP analogue with NO not released). Exogenous NO could obviously alleviate the inhibition effects of salt stress on the seedling growth and photosynthesis via increasing plant dry matter and leaf chlorophyll content, net photosynthesis rate, transpiration rate, and soluble protein content. Exogenous NO enhanced the activities of leaf nitrate reductase, glutamine synthetase, and glutamateoxoglutarate aminotransferase, restrained the activities of protease and glutamate dehydrogenase, decreased the free amino acid content, and improved the nitrate content and ammonium assimilation under salt stress. Applying sodium ferrocyanide did not show any alleviation effect on the seedling growth and nitrogen metabolism under salt stress. As a NO-scavenger, c-PTIO inhibited the growth and nitrogen metabolism under salt stress, but the inhibition effect could be mitigated by supplementing SNP. It was suggested that exogenous and endogenous NO were involved in the regulation of alfalfa nitrogen metabolism under salt stress.

Photosynthetic characteristics of Bothriochloa ischaemum under drought stress and elevated CO₂ concentration.

ZHANG Chang-sheng1, LIU Guo-bin2, XUE Sha1,2, JI Zhi-qing1, ZHANG Chao2

2012, 23(11):  3009-3015. 

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A pot experiment was conducted to study the variations of the photophysiological characteristics of native bluestem (Bothriochloa ischaemum) in loess hillygully region under different soil moisture condition (80% and 40% field capacity) and different atmospheric CO₂ concentration (375 μmol·m^-2·s^-1 and 750 μmol·m^-2·s^-1). The results showed that drought stress decreased the maximum photosynthetic rate (P_{n max}), apparent quantum efficiency (AQE), stomatal conductance (g_s), transpiration rate (T_r), maximum photochemical efficiency (F_v/F_m), potential photochemical efficiency (F_v/F_o), and photosynthetic pigments contents, and increased the malondialdehyde (MDA) and proline (Pro) contents. Under sufficient moisture condition, elevated CO₂ concentration didn’t change the P_{n max} and the MDA and Pro contents significantly; under drought stress, elevated CO₂ improved the maximal fluorescence (F_m), F_v/F_m, F_v/F_o, photosynthetic pigments contents, and AQE, and the P_{n max}  under elevated CO₂ was increased significantly by 23.3%, and the MDA and Pro contents were decreased significantly, as compared with those under ambient CO₂ concentration. All the results suggested that elevated CO₂ concentration had definite compensation effect on the photosynthetic reduction of B. ischaemum induced by drought stress, and alleviated the damage of drought stress on B. ischaemum.

Effects of high temperature and humidity on leaf Bt protein expression of transgenic Bt cotton.

ZHANG Xiang, WANG Gui-xia, GU Chao, HAN Yong, XU Ying-fei, CHEN Yuan, CHEN De-hua

2012, 23(11):  3016-3020. 

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Different origins Bt cotton cultivars, including DP410B (conventional cultivar) and Daiza No.1 (hybridized cultivar) from US and Sikang No.1 (conventional cultivar) and Sikang No.3 (hybridized cultivar) from China, were taken as the test materials to investigate the effects of high temperature (37 ℃) and different humidity (50%, 70%, and 90%) on the leaf Bt protein expression of Bt cotton. At high temperature, temperature and humidity had no significant effects on the leaf Bt protein expression of the cultivars at peak squaring stage. At peak flowering stage, as compared with the control (25-30 ℃ and 60%-70% humidity), 37 ℃ and 50% humidity decreased the leaf Bt protein content of conventional cultivars significantly by 2.6%-3.0%. At peak bolling stage, compared with the control, 37 ℃ and 50% humidity decreased the leaf Bt protein content of DP410B, Sikang No.1, and Sikang No.3 significantly by 3.3%-5.8%. Among the four cultivars, DP410B and Daiza No.1 had the highest leaf Bt protein content, while Sikang No.1 had the lowest one.

Impacts of drought stress on the growth and development and grain yield of spring maize in Northeast China.

JI Rui-peng1, CHE Yu-sheng2, ZHU Yong-ning2, LIANG Tao3, FENG Rui1, YU Wen-ying1, ZHANG Yu-shu1

2012, 23(11):  3021-3026. 

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Taking spring maize variety Danyu39 as test object, an  experiment was conducted in a largescale agricultural water controlling experimental field to study the impacts of drought stress at three key growth stages, i.e., 3leaf-jointing, jointingsilking, and silkingmilk ripe, on the growth and development and grain yield of spring maize in Northeast China. Two treatments were installed, including moderate drought stress (MS) and rewatering to suitable water (CK). Compared with CK, the MS at 3-leaf-jointing stage postponed the whole growth period of Danyu39 by 13 d, and the plant height and leaf area at jointing stage were decreased by 29.8% and 41.2%, respectively. After re-watering, the plant height and grain yield recovered obviously, and the differences in ear characteristics and final yield were insignificant. The MS at jointingsilking stage shortened the whole growth period by 7 d, the plant height and leaf area at silking stage were decreased by 18.6% and 14.1%, respectively, the ear length, grain number per ear, ear dry mass, and grain mass per ear decreased by 6.9%, 19.1%, 28.1%, and 29.4%, respectively, and the blank stem rate increased by 13.3%. When the maize suffered from moderate drought stress at silking-milk ripe stage, the whole growth period was shortened by 15 d, the plant height and leaf area at milk ripe stage were decreased by 2.3% and 37.3%, respectively, the ear length, grain number per ear, ear dry mass, and grain mass per ear decreased by 9.2%, 24.1%, 30.8%, and 27.9%, respectively, and the blank stem rate increased by 24.5%. After re-watering at the latter two stages, the recovery of plant height was little, and the grain yield decreased significantly.

Effects of sub-low temperature and drought stress on root morphology and leaf structure of tomato seedlings.

SUN San-jie1, LI Jian-ming1, ZONG Jian-wei2, YAO Yong-zhe1, CHEN Kai-li1

2012, 23(11):  3027-3032. 

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By using WinRhizo 2005a root scanning measurement system and traditional paraffin sectioning method, this paper studied the root morphology and leaf structure of tomato seedlings under effects of sub-low temperature (8-15 ℃) and mild drought stress (55%-70% of normal field capacity). Single treatment of sub-low temperature or mild drought stress promoted the increase of the seedling root length, surface area, and volume, while the interaction of the sub-low temperature and mild drought stress resulted in the decline of the indices. At sub-low temperature or under mild drought stress, the root length increase was promoted via the increase of the proportion of 0.50-1.00 mm diameter class roots, and the increase of the root surface area and volume was promoted via the increase of the proportion of 1.00-2.00 mm diameter class roots. Under the interaction of the sub-low temperature and mild drought stress, the root growth was inhibited owing to the decrease of the proportions of 0.20-0.50 mm and <0.20 mm diameter classes roots. There was a significant negative correlation between the cell tense ratio (CTR) and spongy ratio (SR), and a significant positive correlation between the CTR and palisade tissue thickness/spongy tissue thickness. At sub-low temperature, the palisade tissue thickness decreased; under mild drought stress, both the palisade tissue thickness and the spongy tissue thickness decreased; whereas the interaction of sub-low temperature and mild drought stress made leaf become thinner and palisade tissue thickness/spongy tissue thickness had a significant decrease.  

Effects of exogenous nitric oxide on the subcellular distribution and chemical forms of copper in tomato seedlings under copper stress.

JIANG Chun-hui1, WANG Xiu-feng2, YIN Bo1, LI Xiao-yun1, CUI Xiu-min1

2012, 23(11):  3033-3039. 

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A nutrient solution culture experiment was conducted to study the effects of exogenous NO donor (sodium nitroprusside) on the subcellular distribution and chemical form of copper (Cu) in tomato seedlings under the stress of 50 μmol·L^-1 of Cu²⁺ (CuCl₂). Under this stress, the biomass and plant height of tomato seedlings decreased by 33.7% and 23.1%, respectively. Exogenous NO alleviated this inhibition effect significantly, but the Cu concentration and accumulation in the seedling organs still had a significant increase. Under the Cu stress, the Cu concentration and accumulation in the seedling organs were in the order of root > leaf > stem > petiole. Exogenous NO limited the absorbed Cu transferred from root to shoot, but could not remove this translocation. Exogenous NO increased the Cu concentration in vacuole and cell wall significantly, and decreased the Cu concentration in organelle, which lessened the damage of Cu on the regular metabolic balance in cytoplasm and increased the tolerance of organelle against Cu. Exogenous NO increased the acetic acidextractable Cu (F_HAc) in root, sodium chlorideextractable Cu (F_NaCl) in stem, F_HAc in petiole, and ethanolextractable Cu (F_E) and F_NaCl in leaf, while decreased the concentration and distribution of water-extractable Cu (F_W) in different organs, which efficiently reduced the bio-toxicity of excessive copper.

Effects of straw returning on the integrated soil fertility and crop yield in southern China. 

YANG Fan1, DONG Yan1, XU Ming-gang2, BAO Yao-xian2

2012, 23(11):  3040-3944. 

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Based on the data from 94  experiments of straw returning in Anhui, Jiangxi, Hunan, Hubei, Guangxi, Sichuan, and Chongqing, and by using mathematic modeling approach, this paper evaluated the effects of straw returning on the soil fertility and crop yield in southern China. Obvious regional differences were observed in the soil fertility index (SFI) and crop yield response. In study area, the croplands with the SFI of Grade III and Grade IV were predominant, occupying 69.1% and 21.3% of the total, respectively. Averagely, straw returning increased the SFI and crop yield by 6.8% and 4.4%, respectively, as compared with the control (no straw returning). The SFI was significantly linearly correlated with rice yield, and could well reflect the integrated soil fertility in study area. At present, straw returning with decomposing agent added is one of the most important measures to improve the integrated soil fertility in southern China, which should be widely popularized.

Effects of temperature on the growth and development of Aglossa dimidiata parasitized on Litsea coreana.

SHANG Xiao-li1, YANG Mao-fa1, HUANG Li1, GOU Guang-qian2

2012, 23(11):  3045-3050. 

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In order to reveal the effects of temperature on the growth and development of Aglossa dimidiata  parasitized on Litsea coreana, a laboratory experiment was conducted to study the mean development duration, development rate, and survival rate of A. dimidiata at its different growth stages at 31 ℃, 28 ℃, 25 ℃, 22 ℃, and 19 ℃, with the development threshold temperature and effective accumulated temperature for different growth stages calculated. Temperature had significant effects on the developmental duration. Except that the development duration of egg was shortened with increasing temperature, the development durations of larva, pupa, and immature A. dimidiata were the shortest at 25 ℃, being 249.53±23.83, 12.94±1.27, and 273.00±24.19 days, respectively. There existed significant relationships between the development rates of A. dimidiata at its different growth stages and temperature, with positive linear relationship at egg stage, and quadratic relationship at larva, pupa, and immature stages. Temperature also had significant effects on the survival rate of A. dimidiata. The survival rates of A. dimidiata at its different growth stages were all the highest at 25 ℃, being 94.0%, 73.8%, 91.3%, and 63.4% for the egg, larva, pupa, and immature A. dimidiata, respectively, followed by at 22 ℃ and 19 ℃, and the lowest at 31 ℃. No larva and pupa could survive at 31 ℃, suggesting that A. dimidiata was not resistant to high temperature. The development threshold temperature for egg, larva, pupa, and immature A. dimidiata was 13.21 ℃, 17.12 ℃, 14.76 ℃, and 16.47 ℃, and the effective accumulated temperature was 117.94, 870.88, 149.70, and 1442.75 daydegree, respectively. The results coincided with the fact that the A. dimidiata  reproduced 2 or 3 generations a year in Xifeng area of Guizhou, Southwest China.

Effects of temperature on the development and fecundity of Diachasmimorpha longicaudata (Ashmead).

LIU Chun-yan1,2, CHEN Ke-wei1, ZENG Ling1

2012, 23(11):  3051-3056. 

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A laboratory experiment was conducted to investigate the growth and reproduction of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) reared on the 3rd instar larvae of Bactrocera dorsalis (Diptera: Tephritidae) at 15, 18, 21, 24, 27, and 30  ℃. Within the range of test temperatures, the generational development time shortened with increasing temperature, from about 45.7 days at 15 ℃ to 15.2 days at 30 ℃. Excessively low or high temperature had definite inhibition effect on the development of D. longicaudata. At 15 ℃ and 30 ℃,  the survival rate of D. longicaudata at immature stages (i.e., from egg to adult) was 10.2% and 31.3%, respectively; while at 24-27 ℃,  the survival rate was above 50%. The longevity of D. longicaudata decreased with increasing temperature, and that of the females was usually longer than that of the males. The fecundity of D. longicaudata was the highest (74.2 progenies) at 24 ℃, followed by at 27 ℃ (53.4 progenies), at 21 ℃ (35.7 progenies), and at 18 ℃ (31.6 progenies). At 15 ℃ and 30 ℃, no more than 20 progenies were observed. At 15-24 ℃, the female/male ratio increased with increasing temperature, being the highest (0.59) at 24 ℃; at 21-27 ℃, females predominated in the progenies populations. The intrinsic increase rate (r_m) was the highest (0.1318) at 27 ℃, followed by at 24 ℃ (0.1239), at 21 ℃ (0.0747), at 30 ℃ (0.0318), and at 18 ℃ (0.0187). At 15 ℃, the intrinsic increase rate and population trend index were -0.0240 and 0.8, respectively, indicating that the population at this temperature presented a negative increasing trend. The favorite temperature range for the development and reproduction of D. longicaudata was from 24 ℃ to 27 ℃.

Characteristics of soil nematode communities in coastal wetlands with different vegetation types.

LIU Bei-bei, YE Cheng-long, YU Li, JIAO Jia-guo, LIU Man-qiang, HU Feng, LI Hui-xin

2012, 23(11):  3057-3064. 

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An investigation was conducted on the characteristics of soil nematode communities in different vegetation belts (Spartina alterniflora belt, Sa; Suaeda glauca belt, Sg; bare land, Bl; Phragmites australis belt, Pa; and wheat land, Wl) of Yancheng Wetland Reserve, Jiangsu Province of East China. A total of 39 genera and 20 families of soil nematodes were identified, and the individuals of dominant genera and common genera occupied more than 90% of the total. The total number of the nematodes differed remarkably with vegetation belts, ranged from 79 to 449 individuals per 100 grams of dry soil. Wheat land had the highest number of soil nematodes, while bare land had the lowest one. The nematode ecological indices responded differently to the vegetation belts. The Shannon index (H) and evenness index (J) decreased in the order of Pa > Sg > Wl > Sa > Bl, and the dominance index (λ) was in the order of Bl > Sa > Wl > Sg > Pa, suggesting that the diversity and stability of the nematode community in bare land were lower than those in the other vegetation belts, and the nematode community in the bare land tended to be simplified. The maturity index (MI) was higher in uncultivated vegetation belts than in wheat land, suggesting that the wheat land was disturbed obviously. The nematode community structure differed significantly with vegetation belts, and the main contributing species in different vegetation belts also differed. There existed significant correlations between the soil physical and chemical characteristics and the nematode numbers, trophic groups, and ecological indices. Our results demonstrated that the changes of soil nematode community structure could be used as an indicator well reflecting the diversity of vegetation belt habitat, and an important bio-indicator of coastal wetland ecosystem.

Effects of two years planting transgenic Bt rice (BtSY63) on soil nematode community.

LI Xiu-qiang1,2, CHEN Fa-jun3, LIU Man-qiang1, CHEN Xiao-yun1, HU Feng1

2012, 23(11):  3065-3071. 

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A two-year field experiment was conducted to evaluate the effects of planting transgenic Bt rice (BtSY63) and its nearisogenic nonBt rice (SY63) on the soil nematode abundance, trophic group composition, ecological indices, and community structure. With the planting of BtSY63 and SY63, the soil nematode abundance changed obviously with sampling time, but had no significant difference between planting BtSY63 and SY63. Only at specific sampling time, the percentage of omnivorepredators and the Shannon diversity index of nematode community under the planting of BtSY63 were significantly higher than those under the planting of SY63. The nonmetric multidimensional scaling (nMDS) of nematode community revealed that no significant difference was observed in the nematode community composition between planting BtSY63 and SY63 across all sampling times. In conclusion, two years planting BtSY63 had no deleterious effects on the soil nematode community.

Effects of continuous enclosure and fertilization on soil microbial community structure in alpine meadow.

ZHANG Li1,2, DANG Jun1,2, LIU Wei1, WANG Qi-lan1, XIANG Ze-yu3 ,WANG Chang-ting3

2012, 23(11):  3072-3078. 

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By using phospholipid fatty acid (PLFA) method, this paper studied the changes of soil microbial community structure in an alpine meadow under six years continuous enclosure and its combination with fertilization, taking grazing area as the control. Both continuous enclosure and its combination with fertilization had significant effects on the microbial flora and total PLFA in different soil layers, and the effects were greater for 0-10 cm than for 10-20 cm soil layer. The species of PLFA in different soil layers also changed significantly. Under enclosure and its combination with fertilization, the number of gramnegative bacteria in different soil layers was lower than that of the control, and the numbers of bacteria, fungi, and gram-positive bacteria and the total PLFA in 0-10 cm soil layer were also lower, but the number of actinomycetes was higher than that of the control. In 10-20 cm soil layer, the number of grampositive bacteria had no significant differences among different treatments, whereas the numbers of bacteria, fungi, and actinomycetes and the total PLFA were notably higher under enclosure but decreased markedly after fertilization. As compared with that of the control, the ratio of bacteria and fungi in different soil layers under enclosure and its combination with fertilization increased, the ratios of saturated fatty acid to monounsaturated fatty acid (SAT/MONO) and of grampositive bacteria to gramnegative bacteria (G⁺/G^-) under enclosure were all lower, but those after fertilization were in adverse. It was suggested that continuous enclosure and its combination with fertilization led to the decline of soil microbial diversity and activity and soil ecosystem stability.

Fungal population structure and its biological effect in rhizosphere soil of continuously cropped potato.

MENG Pin-pin1,2, LIU Xing1,2, QIU Hui-zhen1,2,3, ZHANG Wen-ming1,2,3, ZHANG Chun-hong1,2,3, WANG Di2,3,4, ZHANG Jun-lian2,3,4, SHEN Qi-rong5

2012, 23(11):  3079-3086. 

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Continuous cropping obstacle is one of the main restriction factors in potato industry. In order to explore the mechanisms of potato’s continuous cropping obstacle and to reduce the impact  on potato’s tuber yield, a field experiment combined with PCR-DGGE molecular fingerprinting was conducted to investigate the fungal population structure and its biological effect in rhizosphere soil of continuously cropped potato. With the increasing year of potato’s continuous cropping, the numbers of visible bands in rhizosphere fungal DGGE profiles increased obviously. As compared with that of CK (rotation cropping), the operational taxonomic unit (OTU) in treatments of one to five years continuous cropping was increased by 38.5%, 38.5%, 30.8%, 46.2%, and 76.9% respectively, indicating that potato’s continuous cropping caused an obvious increase in the individual numbers of dominant fungal populations in rhizosphere soil. Also with the increasing year of potato’s continuous cropping, the similarity of the fungal population structure among the treatments had a gradual decrease. The sequencing of the fungal DGGE bands showed that with the increasing year of continuous cropping, the numbers of the potato’s rhizosphere soilborne pathogens Fusarium oxysporum and F. solani increased obviously, while the number of Chaetomium globosum, as a biocontrol species, had a marked decrease in the fifth year of continuous cropping. It was suggested that potato’s continuous cropping caused the pathogen fungal populations become the dominant microbial populations in rhizosphere soil, and the rhizosphere microecological environment deteriorated, which in turn affected the root system, making the root vigor and its absorption area reduced, and ultimately, the tuber yield decreased markedly.

Genetic diversity and population genetic structure of Beauveria bassiana in northern China.

HE Ling-min, HU Xiao-lei, CHEN Xue, ZHANG Sheng-li, LUAN Feng-gang, LI Zeng-zhi

2012, 23(11):  3087-3095. 

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A total of 622 isolates of Beauveria bassiana collected from 13 provinces in northern China were divided into 13 provincial subpopulations, and 568 of the 622 isolates belonging to 8 insect orders and Araneida, whose hosts could be indentified to order level, were divided into 9 host order subpopulations, with the genetic diversity and population genetic structure of the B. bassiana in northern China analyzed by using ISSR (intersimple sequence repeat) technique. All the diversity indices showed that the B. bassiana in northern China had higher genetic diversity and population heterogeneity. Among the B. bassiana subpopulations, Inner Mongolia subpopulation and Lepidoptera subpopulation showed the highest genetic diversity and population heterogeneity, while Henan subpopulation and Araneida subpopulation showed the lowest ones. The genetic differentiation index and genetic distance between Henan and Liaoning subpopulations and between Araneida and Mantodea subpopulations were the highest, while those between Ningxia and Shaanxi subpopulations and between Coleoptera and Hymenoptera subpopulations were the lowest. The mean genetic differentiation index and mean genetic distance between the host order subpopulations were lower than those between the provincial subpopulations. These results and the subpopulation clustering analysis based on the genetic distance of subpopulations all demonstrated that the genetic lineage of B. bassiana isolates in northern China was associated with neither their geographic origin nor their host origin. The variation of B. bassiana in northern China was mainly caused by the variation between families and between genera of different host orders, and also, caused by the diversity between different collection sites and between different microhabitats within the collection sites.

Screening, denitrification characteristics, and anaerobic ammonium oxidation ability of denitrifying bacterium aHD7.

CHU Shu-yi, JIANG Hui-xia, XIAO Ji-bo, SHAN Sheng-dao

2012, 23(11):  3096-3102. 

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A highly efficient denitrifying bacterium aHD7 was screened from activated sludge. After static culture at 30 ℃ for 3 days, the  denitrification rate of the aHD7 reached 91.7%, and during denitrification, nitrite had lower accumulation, with its concentration basically maintained at 1.8 mg·L^-1. The microscopy observation demonstrated that the aHD7 was a gramnegative bacillus, with an average size of 0.5 μm×(1.5-2.5) μm. Based on its biochemical/morphological characteristics and homologic analysis of 16S rDNA sequence, the aHD7 was identified as Pseudomonas mendocina. The investigation on the factors affecting the denitrification capacity of aHD7 showed that at the initial concentration of nitrate nitrogen being less than 276.95 mg·L^-1, the  denitrification rate was almost 100%, and when the initial concentration of nitrate nitrogen was as high as 553.59 mg·L^-1, the denitrification rate could reach 66.8%, with little nitrite accumulated. Ethanol was the most suitable carbon source. C/N ratio 6-8 and pH value 6-9 benefited the denitrification. The aHD7 had a good ability of anaerobic ammonium oxidation, and its average ammonium utilization rate reached 4.56 mg·L^-1·d^-1.

Diversity and enzyme-producing activity of culturable halophilic bacteria in Daishan Saltern of East China.

YANG Dan-dan1, LI Qian2, HUANG Jing-jing1, CHEN Min1

2012, 23(11):  3103-3108. 

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Soil and saline water samples were collected from the Daishan Saltern of East China, and the halophilic bacteria were isolated and cultured by using selective media, aimed to investigate the diversity and enzyme-producing activity of culturable halophilic bacteria in saltern environment. A total of 181 strains were isolated by culture-dependent method. Specific primers were used to amplify the 16S rRNA gene of bacteria and archaea. The operation taxonomy units (OTUs) were determined by ARDRA method, and the representative strain of each OTU was sequenced. The phylogenetic position of all the isolated strains was determined by 16S rRNA sequencing. The results showed that the isolated 181 strains displayed 21 operational taxonomic units (OTUs), of which, 12 OTUs belonged to halophilic bacteria, and the others belonged to halophilic archaea. Phylogenetic analysis indicated that there were 7 genera presented among the halophilic bacteria group, and 4 genera presented among the halophilic archaea group. The dominant halophilic strains were of Halomonas and Haloarcula, with 46.8% in halophilic bacteria and 49.1% in halophilic archaea group, respectively. Enzyme-producing analysis indicated that most strains displayed enzymeproducing activity, including the activities of producing amylase, proteinase and lipase, and the dominant strains capable of enzyme-producing were of Haloarcula. Our results showed that in the environment of Daishan Saltern, there existed a higher diversity of halophilic bacteria, being a source sink for screening enzyme-producing bacterial strains.

Control effect and bacteriostasis of mulberry endophytic bacterium Burkholderia cepacia Lu10-1 on silkworm septicemia. 

DONG Fa-bao, MU Zhi-mei， YU Qi, ZHAO Kai, LIU Zhao-yang, WANG Yan-wen, GAO Hui-ju

2012, 23(11):  3109-3115. 

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A laboratory test was conducted to study the control effect and bacteriostasis of antagonistic bacterium Burkholderia cepacia Lu10-1 isolated from mulberry on silkworm septicemia, aimed to develop a new microbial pesticide to control silkworm diseases. The supernatant of Lu10-1 zymotic fluid achieved 41.2% control efficiency and 24.0% prophylactic effect on silkworm septicemia. The antibacterial crude extract of Lu10-1 had stronger antagonistic activity against Bacillus bombyseptieus. The diameter of inhibition zone reached 18.20 mm, and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the antibacterial crude extract were 1.56 and 3.13 mg·mL^-1, respectively. After treated with the antibacterial crude extract, B. bombyseptieus never appeared logarithmic growth phase, its cell membrane permeability changed, intracellular protein leaked out, intracellular macromolecular protein degraded, and at last, the thalli cracked, inner substances out-flowed, cavity formed, and cell ablated. It was considered that the antagonistic substances of Lu10-1 strain could be used for controlling silkworm septicemia, with preferable development foreground.

Transfer characteristics of cadmium in soilvegetableinsect food chain.

DING Ping1,2, ZHUANG Ping1,2, LI Zhi-an1,2, XIA Han-ping1,2, TAI Yi-ping1,2, LU Huan-ping1,2

2012, 23(11):  3116-3122. 

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Taking two kinds of vegetables (Brassica rapa and Amaranthus mangostanus) and one insect species (Prodenia litura) as test materials, a greenhouse pot experiment was conducted to study the transfer characteristics of cadmium (Cd) in soilvegetableinsect food chain and the distribution patters of different Cd chemical forms in the organs of the two vegetables. With the increasing concentration of applied Cd in soil, the biomass of the two vegetables decreased significantly, while the Cd concentration in the vegetables had a significant increase. The Cd concentration in the vegetable organs decreased in the order of stem > root > leaf for A.  mangostanus, and of stem > leaf > root for B. rapa. The Cd concentration in P. litura larvae also increased with the increasing concentration of Cd in soil, and the maximum Cd concentration in the P. litura larvae on B. rapa and A. mangostanus was 36.7 and 46.3 mg·kg^-1, respectively. In the feces of the larvae on B. rapa and A. mangostanus, the Cd concentration was up to 190 and 229.8 mg·kg^-1, respectively, suggesting that the most part of Cd absorbed by P. litura larvae was excreted out of their bodies via feces. In the organs of the two vegetables, NaClextractable Cd was the dominant Cd form (>70%), followed by dH₂O and ethanolextractable Cd, while the HAcextractable Cd (insoluble cadmium phosphate), HClextractable Cd (insoluble cadmium oxalate), and residual Cd only had a very low concentration. Such a present pattern of different Cd forms in vegetable organs could be conducive to the Cd transfer in the food chain. P. litura could ease Cd poison by excreting large amount of absorbed Cd via feces, and effectively restrict the transfer of Cd to next trophic level. Since B. rapa and A. mangostanus could accumulate large amount of Cd in their biomass, the two vegetables were suggested not to be planted in highly Cdcontaminated soil.

Ecological characteristics and seasonal variation of macrobenthos near the Ningjin coastal water of Shandong, East China.

GAN Zhi-bin1,2, LI Xin-zheng1, WANG Hong-fa1, ZHANG Bao-lin1

2012, 23(11):  3123-3132. 

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The coastal water off Ningjin is located at the eastern end of the Shandong Peninsula, the boundary of the Northern and Southern Yellow Sea. In this paper, the ecological characteristics and seasonal variation of macrobenthic community in this region were studied, based on the investigation data collected from the four cruises in January (winter), April (spring), July (summer), and October (autumn), 2007. A total of 243 macrobenthic species were identified, of which, 96 species were of Polychaeta, 77 were of Crustacea, 43 were of Mollusca, 13 were of Echinodermata, and the rest 14 species were of other benthic groups. The dominant species varied with seasons, but Paralacydonia paradoxa (Polychaeta) and Amphioplus japonicus (Echinodermata) were dominant throughout the four seasons. The average biomass of the macrobenthos estimated from the four cruises was 9.5 g·m^-2, with the highest biomass during the spring cruise and the lowest one during the winter cruise. The average abundance estimated from the four cruises was 219.6 ind·m^-2, with the highest abundance during the winter cruise and the lowest one during the autumn cruise. The Shannon index (H) of the macrobenthos community varied from 2.82 to 3.23, the species richness index (D) varied from 2.28 to 2.75, and the species evenness index (J) varied from 0.82 to 0.86. The Bray-Curtis similarity cluster analysis and MDS ordination analyses indicated that there was a distinct distribution of macrobenthic communities from seashore to offshore, which was closely correlated with the spatial structure of bathymetry and the sediment type in the study region.

Change trend of vegetation cover in Beijing metropolitan region before and after the 2008 Olympics.

SUN Xiao-peng1, WANG Tian-ming1, WU Jian-guo1,2, GE Jian-ping1

2012, 23(11):  3133-3140. 

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The MODIS-NDVI data from 2000 to 2009 were used to analyze the temporal dynamics and spatial distribution of the vegetation cover in the Beijing metropolitan region before and after the 2008 Olympics. During the study period, the proportion of the significantly increased pixels of NDVI occupied 20.7% while that of the significantly decreased pixels only occupied 4.1% of the total, and the decreasing rate of the NDVI was slightly faster than the increasing rate. The significant changes of the NDVI were mainly concentrated in the low altitude and small slope areas with intensive human activities, and two bands were formed in the plain area, i.e., the vegetation increasing band within the 5th Ring Road and the vegetation decreasing band from the 5th Ring Road to the outside areas of the 6th Ring Road. In the areas with significant vegetation change, there was an obvious transition between the high and low NDVI sections but less change in the medium NDVI section, mainly due to the conversion of land cover type. In the Capital  function core area and ecological conservation zones, vegetation change represented a positive trend; while in the urban function expansion area and urban development area, vegetation change had the dual characteristics of both positive and negative trends. A series of ecological engineering projects during the preparatory period of the 2008 Olympics was the main cause of the vegetation increase in the study area.

Accumulative nitrogen deficit models of wheat aboveground part based on critical nitrogen concentration.

ZHAO Ben, YAO Xia, TIAN Yong-chao, LIU Xiao-jun, CAO Wei-xing, ZHU Yan

2012, 23(11):  3141-3148. 

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Based on threeyear field experiments, three models of critical nitrogen concentration dilution curve, nitrogen nutrition index, and accumulative nitrogen deficit were constructed for the aboveground  dry matter in  medium protein wheat variety Yangmai 16 and low protein wheat variety Ningmai 13, respectively. The critical nitrogen concentration dilution curve model had specific biological meaning, i.e., there existed a negative power function correlation between shoot maximum dry matter (DM) and critical nitrogen concentration (N_cnc) (Yangmai 16: N_cnc=4.65DM^-0.44; Ningmai 13: N_cnc=4.33DM^-0.45), the nitrogen nutrition index model could be used for accurate diagnosis of wheat plant nitrogen status, and the accumulative nitrogen deficit model could be used for quantitative regulation of nitrogen fertilizer management. The tests of the derived equations with independent experiment data (2007-2008) showed higher accuracy and reliable prediction, suggesting that the present models could be used for the diagnosis and regulation of wheat nitrogen nutrition, providing a key technical approach to precise fertilization management in wheat production.

Fire behavior of Mongolian oak leaves fuel bed under no-wind and zero-slope conditions. Ⅱ. Analysis of the factors affecting flame length and residence time and related prediction models.

ZHANG Ji-li, LIU Bo-fei, DI Xue-ying, CHU Teng-fei, JIN Sen

2012, 23(11):  3149-3156. 

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Taking fuel moisture content, fuel loading, and fuel bed depth as controlling factors, the fuel beds of Mongolian oak leaves in Maoershan region of Northeast China in field were simulated, and a total of one hundred experimental burnings under no-wind and zero-slope conditions were conducted in laboratory, with the effects of the fuel moisture content, fuel loading, and fuel bed depth on the flame length and its residence time analyzed and the multivariate linear prediction models constructed. The results indicated that fuel moisture content had a significant negative liner correlation with flame length, but less correlation with flame residence time. Both the fuel loading and the fuel bed depth were significantly positively correlated with flame length and its residence time. The interactions of fuel bed depth with fuel moisture content and fuel loading had significant effects on the flame length, while the interactions of fuel moisture content with fuel loading and fuel bed depth affected the flame residence time significantly. The prediction model of flame length had better prediction effect, which could explain 83.3% of variance, with a mean absolute error of 7.8 cm and a mean relative error of 16.2%, while the prediction model of flame residence time was not good enough, which could only explain 54% of variance, with a mean absolute error of 9.2 s and a mean relative error of 18.6%.

Change trends of summer fire danger in Great Xing’an Mountains forest region of Heilongjiang Province, Northeast China under climate change.

YANG Guang1,2, SHU Li-fu2, DI Xue-ying1

2012, 23(11):  3157-3163. 

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By using Delta and WGEN downscaling methods and Canadian Forest Fire Weather Index, this paper analyzed the variation characteristics of summer fire in Great Xing’an Mountains forest region of Heilongjiang Province in 1966-2010, estimated the change trends of the summer fire danger in 2010-2099, compared the differences of the forest fire  in summer, spring, and autumn, and proposed the prevention and control strategies of the summer fire  based on the fire environment. Under the background of climate warming, the summer forest fire  in the region in 2000-2010 showed a high incidence trend. In foreseeable future, the summer forest fire  across the region in 2010-2099, as compared to that in the baseline period 1961-1990, would be increased by 34%, and the increment would be obviously greater than that of spring and autumn fire. Relative to that in 1961-1990, the summer fire  in 2010-2099 under both SRES A2a and SRES B2a scenarios would have an increasing trend, and, with the lapse of time, the trend would be more evident, and the area with high summer fire would become wider and wider. Under the scenario of SRES A2a, the summer fire  by the end of the 21st century would be doubled, as compared to that in 1961-1990, and the area with high summer fire  would be across the region. In the characteristics of fire source, attributes of forest fuel, and fire weather conditions, the summer forest fire  was different from the spring and autumn forest fire, and thus, the management of fire source and forest fuel load as well as the forest fire forecast (mid-long term forecast in particular) in the region should be strengthened to control the summer forest fire.  

Eco-fitness of county-level agricultural leading industry structure: Assessment and development prediction.

WANG Liang, ZHU Li-qun, ZHANG Si-wei, ZHANG Pei-qi, XU Min-lun, BIAN Xin-min

2012, 23(11):  3164-3172. 

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Based on the ‘three critical points’ theory of eco-fitness, and by using dynamic weighting and fitting methods, an assessment system for the eco-fitness of county-level agricultural leading industry structure was constructed, and, taking Zhangqiu of Shandong Province, East China as a case, the eco-fitness of county-level agricultural leading industry structure was assessed and predicted. Due to the limited agro-ecological resources, the comprehensive eco-fitness index of four kinds of agricultural leading industry in Zhangqiu presented an upward trend from 2005 to 2010, but a downward trend from 2011 to 2015. The eco-fitness indices of oil crops and fruits would be negative in 2015. The applied research in Zhangqiu confirmed the validity of the assessment system constructed for the ecofitness of county-level agriculture leading industry structure and the rationality of the prediction model.

Reconstruction of urban land space based on minimum cumulative resistance model: A case study of Xintang Town, Guangzhou City.

ZHONG Shi-yu1,2, WU Qing1, LI Yu1, CHENG Jin-ping1

2012, 23(11):  3173-3179. 

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Based on the source-sink landscape theory and the principles of ecosystem services, the minimum cumulative resistance (MCR) model was modified, where the urban center construction land was taken as the expansion source, and the contribution rate of ecological land ecosystem services value was considered as the resistance coefficient. With the modified MCR, the urban spatial expansion process of Xintang Town, Guangzhou City was successfully simulated, and, based on the protection of ecological security pattern, the optimum path for reconstructing urban land space was put forward. The simulated urban spatial expansion short path in 1988-2008 was in accordance with the real situation. By the modified MCR, the urban space  was divided into four zones of high, higher, medium, and low resistance, with the area of 80.84, 78.90, 24.26, and 61.88 km², respectively. The expansion path of the urban space was along the route from low to medium and then to high resistance zones successively. The land suitable for eco-protection and construction had an area of 159.74 km² and 86.14 km², while the ecological conflict area (17.37 km²) was mainly located in higher and high resistance zones, being 10.38 and 6.99 km², respectively. The modified MCR could not only effectively reflect the distribution area of urban land use and the conflict relationship between urban construction and ecological protection, but also reasonably judge the best developmental short path for urban spatial expansion.

Spatiotemporal dynamic fuzzy evaluation of wetland environmental pollution risk in Dayang estuary of Liaoning Province, Northeast China based on remote sensing.

SUN Yong-guang, ZHAO Dong-zhi, ZHANG Feng-shou, WEI Bao-quan, CHU Jia-lan, SU Xiu

2012, 23(11):  3180-3186. 

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Based on the aerial image data of Dayang estuary in 2008, and by virtue of Analytic Hierarchy Process (AHP), remote sensing technology, and GIS spatial analysis, a spatiotemporal evaluation was made on the comprehensive level of wetland environmental pollution risk in Dayang estuary, with the impacts of typical human activities on the dynamic variation of this comprehensive level discussed. From 1958 to 2008, the comprehensive level of the environmental pollution risk in study area presented an increasing trend. Spatially, this comprehensive level declined from land to ocean, and showed a zonal distribution. Tourism development activities unlikely led to the increase of the comprehensive level, while human inhabitation, transportation, and aquaculture would exacerbate the risk of environmental pollution. This study could provide reference for the sea area use planning, ecological function planning, and pollutants control of estuary region.  

Research advances in simulating land water-carbon coupling.

LIU Ning1, SUN Peng-sen1, LIU Shi-rong2

2012, 23(11):  3187-3196. 

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The increasing demand of adaptive management of land, forest, and water resources under the background of global change and water resources crisis has promoted the comprehensive study of coupling ecosystem water and carbon cycles and their restrictive relations. To construct the water-carbon coupling model and to approach the ecosystem water-carbon balance and its interactive response mechanisms under climate change at multiple spatiotemporal scales is nowadays a major concern. After reviewing the coupling relationships of water and carbon at various scales, this paper explored the implications and estimation methods of the key processes and related parameters of watercarbon coupling, the construction of evapotranspiration model at large scale based on RS, and the importance of this model in watercarbon coupling researches. The applications of assimilative multivariate data in watercarbon coupling researches under future climate change scenarios were also prospected.

Lake eutrophication modeling in considering climatic factors change: A review.

SU Jie-qiong1,2, WANG Xuan1,2, YANG Zhi-feng1,2

2012, 23(11):  3197-3206. 

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Climatic factors are considered as the key factors affecting the trophic status and its process in most lakes. Under the background of global climate change, to incorporate the variations of climatic factors into lake eutrophication models could provide solid technical support for the analysis of the trophic evolution trend of lake and the decision-making of lake environment management. This paper analyzed the effects of climatic factors such as air temperature, precipitation, sunlight, and atmosphere on lake eutrophication, and summarized the research results about the lake eutrophication modeling in considering climatic factors change, including the modeling based on statistical analysis, ecological dynamic analysis, system analysis, and intelligent algorithm. The prospective approaches to improve the accuracy of lake eutrophication modeling with the consideration of climatic factors change were put forward, including 1) to strengthen the analysis of the mechanisms related to the effects of climatic factors change on lake trophic status, 2) to identify the appropriate simulation models to generate several scenarios under proper temporal and spatial scales and resolutions, and 3) to integrate the climatic factors change simulation, hydrodynamic model, ecological simulation, and intelligent algorithm into a general modeling system to achieve an accurate prediction of lake eutrophication under climatic  change.

Research advances in the effects of environmental factors on the growth and development of Aurelia spp.

WANG Jian-yan1, YU Zhi-gang2, ZHEN Yu3, MI Tie-zhu3, YAO Qing-zhen2, WANG Guo-shan1

2012, 23(11):  3207-3217. 

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Aurelia spp. is a cosmopolitan coastal species, and also, one dominant species of large jellyfish in the coastal waters of China. In recent years, Aurelia spp. bloom events occur frequently in the world, causing severe damage to marine ecosystems, coastal economy, and society development. Aurelia spp. has a complicated life history comprising a benthic asexually-reproducing polyp generation and a sexuallyreproducing medusa generation, and various vegetative reproduction (budding, strobilation, and podocyst production) and sexual reproduction. Surrounding physical and biological factors affect each growth stage of Aurelia spp., especially the juvenile stage of planktonicbenthic life cycle, which has major effect on the population dynamics of Aurelia spp. This paper reviewed the research advances in the effects of environmental factors on Aurelia spp. at its different growth and development stages, and discussed some problems worthy of further study, aimed to provide useful reference for the research of the key factors controlling the jellyfish blooms in coastal waters of China.  

Biodegradation of organic pollutants by thermophiles and their applications: A review.

CUI Jing-lan1, CHEN Chen1, QIN Zhi-hui1,2, YU Chun-na3, SHEN Hui1, SHEN Chao-feng1,2, CHEN Ying-xu1,2

2012, 23(11):  3218-3226. 

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Persistent organic pollutants have increasingly become a  critical environmental concern, while thermophiles have the high potential of degrading various kinds of environmental organic pollutants. At high temperatures, thermophiles have higher metabolic activity, and the competition by mesophiles is reduced, meanwhile, the solubility and bioavailability of some persistent organic pollutants are greatly increased, and thus, the degradation of the pollutants by thermophiles is more rapid and complete. Therefore, thermophils are of great significance for the biotreatment of organic wastewater and the bioremediation of organic pollutantscontaminated sites. This paper introduced the research progress on the degradation of organic pollutants by thermophiles in terms of the characteristics of thermophiles in degrading organic pollutants, the effects of temperature on the degradation, the degradation pathways, the degradation enzymes, their coding genes, and practical engineering applications. The future research directions including the degradation mechanisms of thermophiles, their resources reserve, related technology strategies and their applications were also prospected.