Table of Content

15 March 2007, Volume 26 Issue 03

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Articles

Effects of elevated CO₂ on the growth and nutrient contents of Betula albosinensis seedlings with two planting densities

QIAO Yun-zhou¹;WANG Kai-yun^1,2; ZHANG Yuan-bin¹

2007, 26(03):  301-306 . 

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By using growth chamber, Betula albosinensis seedlings were planted with two densities (28 and 84 plants·m^-2) and treated with 350 and 700 μmol CO₂·mol^-1 to study the effects of elevated CO₂ on the growth and nutrient contents of the seedlings. The results showed that under elevated CO₂, the plant height, leaf area index, net assimilation rate and relative growth rate of B. albosinensis seedlings with both of the two planting densities increased, while the leaf-mass ratio and specific leaf area decreased. Elevated CO₂ increased the dry mass of stem, branch, leaf and root and the uptake of N and P per plant, but decreased the N and P contents of each organ. It also benefited the use efficiency and accumulation rate of N and P. The decrease of N and P contents in each organ was mainly resulted from the dilution effect of the rapid accumulation of biomass, while the increase of N and P use efficiency might be helpful to the alleviation of the impact of soil nutrients deficiency, a limiting factor on the productivity of subalpine and alpine mountain forests owing to the elevated CO₂ environment in the future. The increment of plant growth under elevated CO₂ decreased with increasing planting density, and the more enhancement of nutrient uptake per plant was observed under low than under high planting density, mainly because the increase of planting density significantly decreased the dry mass of B. albosinensis seedlings.

Carbon concentration and its characteristics in terrestrial higher plants

ZHENG Wei-jie^1,2; BAO Wei-kai²; GU Bin¹; HE Xiao^1,2; LENG Li²

2007, 26(03):  307-313 . 

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A precise estimation of vegetation carbon storage is the key of illustrating the effects of vegetative restoration on the carbon balance in terrestrial ecosystem. In common, this carbon storage is estimated by carbon concentration coefficient and biomass. This paper collected the actual data of various plants carbon concentration, and analyzed the characteristics of the carbon concentration in different plant life types, plant tissues, and different areas. The results showed that plant carbon concentration was in the range of 24.95%-55.44%, with an average of (43.63±0.14) %. The average carbon concentration of different life types was arbor (46.22%)＞shrub (45.93%)＞bryophyte (41.64%)＞herbage (37.13%), and that of different tissues was flower (48.52%)＞fruit (47.19%)＞branch (45.42%)＞stem (44.48%)＞leaf (43.36%)＞root (42.88%). As for different geographical areas, the average carbon concentration was high latitude area (50.30%)＞low latitude area (45.30%)＞middle latitude area (39.68%), and there were significant differences among different climatic types. As a result, error always existed when fixed coefficients were used to estimate the carbon storage.

Quantitative analysis of endangered Acanthopanax senticosus communities in Dongling Mountain

XU Yun； ZHANG Jin-tun

2007, 26(03):  314-318 . 

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Based on the survey of community plots, a quantitative analysis of endangered Acanthopanax senticosus communities in Dongling Mountain was performed with two way indicator species analysis (TWINSPAN), detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA). The communities of A. senticosus were classified into 9 types by TWINSPAN, and the results were validated by DCA. On the DCA graph, the first axis reflected the gradient of altitude, and the second axis reflected the aspect and slope. A. senticosus was more distributed in the thick forests at high altitude and with low light. Except as a dominant species of shrub layer in a few communities, A. senticosus had a relatively less distribution. With accordance to DCA, the results of CCA also showed the trend that the distribution of A. senticosus communities changed with the gradient of environmental factors. Altitude and light were the main factors affecting A. senticosus growth.

Economic value of vegetation carbon fixation and oxygen release in Loess Plateau of North Shaanxi Province under land-use and land-cover change

XIE Hong-xia^1,2; REN Zhi-yuan¹; LI Rui^1,2

2007, 26(03):  319-322 . 

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By using land-use and meteorological data, estimation was made on the economic value of vegetation carbon fixation and oxygen release in the Loess Plateau of North Shaanxi under land-use and land-cover change. Compared with that in 1986, this economic value in 1996 and 2001 was increased by 9.97718×10⁸ yuan and 1.361481×10⁹ yuan, respectively. The policies of returning farmland to forest and grassland and of reasonably controlling the increase of urbanization area were of significance in improving the ecological functions of the Loess Plateau in North Shaanxi Province.

Carbon density, storage and distribution in birch forest ecosystem on the forestland converted from farmland

WU Xiao-shan;HUANG Cong-de

2007, 26(03):  323-326 . 

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The study on the carbon density, storage and distribution in a five-year birch forest on the forestland converted from farmland showed that in different organs of birch, carbon density ranged from 0.4519 to 0.5137 g C·g^-1, and decreased in the order of branch >trunk>leaf>root. The carbon density in floor was 0.3953 g C·g^-1, and that in soil was 0.0150 g C·g^-1 on average, being declined with soil depth. The total carbon storage in the birch forest ecosystem amounted to 127.9298 t C·hm^-2, of which, overstory stored 21.9282 t C·hm^-2, accounting for 17.14%, floor stored 0.3401 t C·hm^-2, accounting for 0.27%, and soil within the depth from 0 to 60 cm stored 105.6615 t C·hm^-2, accounting for 82.59% of the total. The carbon storage in different organs of birch was positively related to its biomass.Stem accumulated the highest biomass, and comprised 57.33% of carbon storage in overstory. The annual net productivity of birch trees was 8.9912 t C·hm^-2·a^-1, and the annual carbon storage was up to 4.4537 tC·hm^-2·a^-1. Compared with that before the conversion of farmland to forestland, the carbon storage of birch forest ecosystem on the converted forestland was increased by 15.4797 t C·hm^-2.

Spatial characteristics of farmland and residential land in dry valley of Minjiang River upper reaches

YANG Zhao-ping^1,2; CHANG Yu¹; WEN Qing-chun^1,2

2007, 26(03):  327-331 . 

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By using FRAGSTATS 3.3 software, this paper calculated the total area, patch number, patch density, and fractal dimension of the farmland and residential land in dry valley of Minjiang River upper reaches based on the spatial neighboring properties of the farmland and residential land analyzed by ARCMAP 9.0 and the relationships between their distribution and topographic factors altitude and slope studied based on DEM. The results showed that shrub land was the landscape radix of the dry valley. The farmland and residential land in the valley had small mean patch size and patch density, and their shapes were simple. Most farmlands were distributed on the steep slopes at the elevations ranging from 1 700 to 3 000 m, and adjacent to shrub land patches. Residential patches had far distances among each other, with a relatively dense distribution at low altitude, but very sparse distribution at high altitude. The spatial distribution pattern of residential land was most affected by that of farmland.

Yield estimation model for different utilization status grassland based on remote sensing data

TAO Wei-guo^1，2; XU Bin^1，2; LIU Li-jun²; YANG Xiu-chun^1，2; QIN Zhi-hao^1，2

2007, 26(03):  332-337 . 

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Based on the observation data obtained from five representative steppes, i . e . , temperate meadow steppe, temperate steppe, temperate desert steppe, temperate steppe-desert and temperate desert in Inner Mongolia, regression models were established to express the relations between each grassland biomass and four vegetation indices, with the information about grassland utilization status considered. The qualitative variable utilization status was introduced into remote sensing estimation models as a dummy variable, and the optimal mixed estimation models and vegetation indices for three types of utilization status were selected. The results showed that EVI was the best index reflecting grassland yield variation, and the average estimation precision of the models was 80%. The precision of the mixed models introduced with utilization status (mixed model Ⅱ) arrived to 79%, being higher than that of the models without the information of utilization status. Comparing with the models established for different utilization status, mixed model Ⅱ had the advantages of concision and convenience.

Growth and decay patterns of riparian Canna glauca and Vetiveria zizanioides

LI Rui-hua^1,2; GUAN Yun-tao^1,3,4; HE Miao¹; HU Hong-ying¹; JIANG Zhan-peng¹

2007, 26(03):  338-343 . 

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The study on the growth and decay of Canna glauca and Vetiveria zizanioides in a pilot scale trial of riparian ecosystem restoration showed that both C. glauca and V. zizanioides didn’t have strong endurance in deep water. C. glauca did not adapt to the water body in a depth more than 20 cm, but V. zizanioides could grow in deeper water depth. The aboveground biomass of C. glauca and V. zizanioides was 27.5% and 79% more than their underground biomass, and the harvest of their aboveground biomass could remove 59% and 57％of total N and 55% and 57% of total P, respectively. After dunked in water for 130 days, the aboveground part of C. glauca lost 31.89% of its dry mass, 49.43% of total N, and 77.30% of total P, while that of V. zizanioides lost 19.8% of its dry mass, 47.54% of total N, and 86.06% of total P. The dunking of the plants induced the release of organic materials, N and P, but the concentrations of COD, NH⁺₄-N and TP in water didn’t have a persistent increase.

Variation characters of agrometeorological elements in Loess Plateau of East Gansu

WAN Xin^1,2; WANG Run-yuan¹; LI Zong-yan¹

2007, 26(03):  344-347 . 

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The analysis on the 1971-2000 meteorological data showed that in the Loess Plateau of East Gansu, air temperature had an obvious increasing trend, especially in winter and spring, and the mean, maximum and minimum temperature increased simultaneously. The maximum temperature got its peak at the turn of seasons, while the minimum temperature always presented increasing trend, with larger increment than that of the maximum temperature. Both the minimum and maximum temperatures were increased obviously in December. Under the effects of climate warming, evaporation increased notably, and the beginning of boundary temperature was advanced while its ending was delayed. The accumulated temperature of ≥0 ℃ and ≥10℃ increased, frost-free period lengthened, and soil moisture in spring and autumn reduced. No significant variation was observed in precipitation, bright sunshine duration, solar radiation, and air relative humidity. The variation of these elements caused by climate warming had both advantages and disadvantages to agricultural production. To improve agricultural economic benefits, agricultural administrative departments should adjust and optimize farming systems in time, go after profits and avoid disadvantages, and make full use of climate resources, according to the variation characters of local climate.

Effects of NaCl stress on K⁺, Na⁺ and Cl^- allocation in different organs of Cucumis sativus L. seedlings

WANG Su-ping; GUO Shi-rong; HU Xiao-hui; JIA Yong-xia; JIAO Yan-sheng

2007, 26(03):  348-354 . 

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By the method of hydroponics, this paper studied the effects of different concentration NaCl on the allocation of K⁺, Na⁺ and Cl^- in the seedlings of two Cucumis sativus L. cultivars with different levels of salt-tolerance. The results showed that under NaCl stress, the seedlings K⁺ content decreased, while their Na⁺ and Cl^- contents increased, with the increase in salinity. Among the test organs, stem had the highest content of Na⁺ and Cl^-, while upper leaves had the lowest. The decrease of K⁺ content in upper leaves was less than that in other organs. Compared with salt-susceptible cultivar ‘Jinchun No. 2’, salt-resistant cultivar ‘Changchun Mici’ had a higher transportation selectivity of K⁺ to Na⁺ from root to stem, and of K⁺ to Na⁺ and Cl^- to Na⁺ from stem to upper leaves, and retained more Na⁺ in root. As a result, ‘Changchun Mici’ accumulated more K⁺ and less Na⁺ in its leaves, and the ratios of leaf K/Na and Cl/Na were higher.‘Changchun Mici’ also had a higher biomass than ‘Jinchun No. 2’ under same salinity. All of these suggested that the higher accumulation of Na⁺ in roots and the lower transportation selectivity of Na⁺ from stem to upper leaves were the main reasons for the stronger salt-tolerance of ‘Changchun Mici’.

Stereotyped behavior of captive Moschus sifanicus in Xinglong Mountain Nature Reserve

MENG Xiu-xiang^1,2; YANG Qi-sen²; FENG Zuo-jian²; XU Hong-fa³

2007, 26(03):  355-358 . 

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From March 2001 to January 2002, the stereotyped behavior of Moschus sifanicus was studied in a deer farm of Xinglong Mountain Nature Reserve. Focal sampling method was used to observe and record the stereotyped behavior patterns of M. sifanicus and the potential differences among its special populations classified by some variables such as age, gender, and reproduction history,etc. The results showed that abundant stereotyped behavior was formed by the captive M. sifanicus in the farm, and the expression duration of this behavior was less for female than for male, which was supposed to be related to the nursing activity of the former. The deer captured from the wild expressed less stereotyped behavior than that born in captivity , because of the artificial lactating history of the former. Sub-adult M. sifanicus expressed more stereotyped behavior than the adult, and the stereotyped behavior of M. sifanicus older than 5.5 years was most intensive. The key period for the stereotyped behavior formation of M. sifanicus was 2.5 and 4.5 years old, and the individuals with successful reproduction had less stereotyped behavior than those with failed reproduction, although the difference was not significant.

Social hierarchy and its seasonal changes of marked Lasiopodomys brandtii population

WAN Xin-rong¹; ZHANG Xin-jie^1,2; LIU Wei¹; WANG Guang-he¹; WANG Meng-jun¹; ZHONG Wen-qin¹

2007, 26(03):  359-362 . 

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With marking-recapture, hair dyeing, and field observation, this paper studied the social hierarchy and its seasonal changes of Lasiopodomys brandtii in Xilinguole district of Inner Mongolia. The results revealed that in reproductive season, an obvious social hierarchy existed in the family groups of L. bramdtii. The social status from high to low was over-wintering males, over-wintering females, adult newborn females, adult newborn males,and sub-adults and juveniles. Since the newborn males had a lower social status, there was little chance for an adult newborn male to mate within an over-wintering male’s territory. Over-wintering males played a critical role in the population reproduction. By the end of reproductive season, the social status of over-wintering males began to fall down, while that of the newborn males promoted gradually. The present study supported the hypothesis about the polygynous mating system of L. bramdtii.

Overwintering and early rearing of Latrodectus tredecimguttatus baby spiders

DUAN Zhi-gui; YAN Xiao-jun; DENG Xing-can; WANG Xian-chun

2007, 26(03):  363-367 . 

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Overwintering and early rearing of Latrodectus tredecimguttatus baby spiders is the key of artificially rearing the spiders. Through the comparison of the hatch rate, survival rate, and average body mass of overwintered baby spiders under different preservation temperature and duration, this paper studied the overwintering pattern of L. tredecimguttatus baby spiders, and the effects of relative humidity, environmental temperature and food on the early growth and development of the baby spiders after leaving egg bags. The results showed that the optimal temperature for the preservation and overwintering of the egg bags was around 4 ℃, but the survival rate of baby spiders decreased gradually after 7 months of the preservation under this temperature, and got to zero after 13 months. To let the eggs hatch out, egg bags should be placed indoor for a period of time (around 2 months) before preserved at low temperature. After left egg bag and reared with Tenerio molitor for four weeks, the average body mass of overwintering baby spiders under 55%-60% relative humidity and 25 ℃-30 ℃ increased by 40- or more fold, with a survival rate greater than 80%.

Grazing behavior of 4-month old Nanjiang yellow goat ram

XU Yong-feng^1,2; LUO Hai-ling^1,2; ZHAO Heng-bo^1,2; CHEN Yu³

2007, 26(03):  368-371 . 

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A successive observation was made on the diurnal grazing behavior of four healthy 4-month old Nanjiang yellow goat rams in summer. The rams were free grazing at daytime, and supplemented with concentrated forage at night. The results showed that the duration of their intake at daytime and night was 513.75 min, occupying 35.68% of the total duration of their activities, and that of rumination, stroll, standing, and sleeping was 289.00, 113.00, 89.75, and 361.50 min,respectively. The duration of intake, standing, excretion and stroll were longer and the frequency of fighting was more at daytime than at night, while the duration of rumination or sleeping was shorter at daytime than at night. The duration ratio of rumination to intake was 0.56:1.00, and the total number of ruminated cuds at daytime and night was 422.25. Nanjiang yellow goat was approved to be fast intake, good in tolerance, and able to bear low quality forage and various climate conditions.

Temporal and spatial fluctuation of macrobenthos community in a newly established wetland in Yangtze River Estuary

ZHOU Xiao; GE Zhen-ming; SHI Wen-yu; WANG Tian-hou

2007, 26(03):  372-377 . 

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To understand the temporal and spatial fluctuations of macrobenthos community in a newly established Jiuduansha wetland in Yangtze River Estuary, an investigation was made on the main habitats of three shoals in the wetland from November 2004 to October 2005. The results showed that the macrobenthos community in the wetland had the highest biomass and density in spring, which declined in summer and autumn and went up in late autumn and winter. The overall diversity of macrobenthos species was relatively low and distributed unevenly. There was a significant difference in macrobenthos densities between Shangsha and Zhongsha in summer, and the spatial grads of macrobenthos density and biomass was in the sequence of Xiasha>Shangsha>Zhongsha in all seasons. The trade-off of dominant species groups had a significant effect on the temporal and spatial fluctuations of macrobenthos community. The density and biomass of macrobenthos were the highest in Scirpus mariqueter and S. triqueter and the second in Phragmites australis and Spartina alterniflora zones during the whole year, and the lowest with extensive seasonal fluctuation in intertidal mudflat zones. No significant difference in the community characteristics of macrobenthos was observed between alien S. alterniflora and native P. australis zones.

Geostatistic analysis on population dynamics of second generation cotton bollworm

LIU Qing-nian¹; LIU Jun-zhan¹; LIU Jing-tao¹; ZHANG Lu-sheng¹; LI Jian-qing²

2007, 26(03):  378-382 . 

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By the methods of geostatistics, this paper analyzed the temporal structural characters and autocorrelations of the population dynamics of second generation cotton bollworm (Helicoverpa armigera) in Binzou City of Shandong Province in 1965—2004. Optimal simulation models were selected based on the decision coefficient R² and Akaike’s Information Criteria (AIC). The results showed that the optimal simulation models of the amount of overwintering pupae(Ⅰ), accumulated amount of eggs on 100 cotton plants (Ⅱ), and occurrence degree (Ⅲ) of second generation H. armigera were all of spherical. These three indices had an aggregative distribution, and their change ranges were 10.41, 12 and 12.06 years, respectively, with a high accordance. The temporal autocorrelations of the three indices were 53.22%, 52.62% and 69.06%, respectively, and the population variance resulted from the structural characters of the indices ranged from 25% to 75%, being a medium degree of spatial autocorrelation with the sequence of Ⅱ<Ⅰ<Ⅲ, while the spatial variance resulted from the random parts ranked in adverse.

Scanning electron-microscopic observation on morphologic damage of Hydra pseudoligactis under Pb²⁺ and Cd²⁺ pollution

WU Ben-fu; HAO Jia-sheng; ZHAO Hua-bin; CHEN Na; SU Cheng-yong

2007, 26(03):  383-388 . 

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Hydra pseudoligactis was treated with different concentrations of Pb²⁺ and Cd²⁺, and the variations of its surface ultra-structure were observed by scanning electron-microscopy. The results showed that the variation of H. pseudoligactis surface ultra-structure was correlated with the kinds of test ions, their concentrations and exposure time, and generation number of H. pseudoligactis. Under the ion concentrations of ≥0.04 mg Cd²⁺·L^-1 and ≥0.25 mg Pb²⁺·L^-1, the surface ultra-structural damage increased with exposure time, and was irreversible. The epidermis corroded, collapsed and disintegrated, and the epitheliomuscular cells, interstitial cells and nematocysts mostly deformed and decreased in number. Especially for nematocysts, they were continuously cracked with exposure time. The morphologic damage of the same generation H. pseudoligactis surface ultra-structure was more serious under Cd²⁺ than under Pb²⁺ exposure.

Degradation effect of ectomycorrhizal fungi-inoculated Fraxinus sogdiana on petroleum hydrocarbon in soil

CHENG Guo-ling¹;LI Pei-jun²

2007, 26(03):  389-392 . 

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With pot experiment, this paper studied the degradation effect of Fraxinus sogdiana inoculated with ectomycorrhizal fungi E1-Hebeloma mesophaeusm, E2-Lactarius insulsns, E3-Strobilomyces floccopus, and E4-Cortinarius russus on the petroleum hydrocarbon in soil of Shenfu sewage irrigation area. The results showed that the degradation rate of soil petroleum hydrocarbon was enhanced by 23.6% when the F. sogdiana was inoculated with the 4 species of ectomycorrhizal fungi together, and by 21.0% and 12.7% when inoculated with E1E3, and E2E4, respectively, compared with the control. Inoculation with ectomycorrhizal fungi could improve the growth of F. sogdiana, and especially, increase its root biomass and the number of side-roots. When inoculated with E1E3, E2E4, and four associated ectomycorrhizal fungi, the number of side-roots increased by 100%, 67%, and 81%, respectively, and a significant positive correlation was observed between the degradation rate of soil petroleum hydrocarbon and the number of side-roots, suggesting that the increase of side-root number was the main reason for the increasing degradation rate of petroleum hydrocarbon in soil.

Effects of exogenous nitric oxide donor SNP on seed germination and seedling growth of Lolioum multiflorum

LIU Jian-xin; WANG Xin; LEI Rui-xia

2007, 26(03):  393-398 . 

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By the method of solution culture, this paper studied the effects of different concentrations exogenous nitric oxide (NO) donor (sodium nitroprusside, SNP) on the seed germination and seedling growth of ryegrass (Lolioum multiflorum). The results showed that 50 and 100 μmol SNP·L^-1 increased the seed germination rate, seedling’s dry matter accumulation, germinated seed α-amylase activity, and leaf soluble protein and chlorophyll contents. The reduced glutathione (GSH) and ascorbic acid (ASC) contents and the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) activities in seedling’s roots and leaves also increased, but the generation of O₂^-_·and the accumulation of malondialdehyde (MDA) and H₂O₂ decreased. High concentration SNP (500-2000 μmol SNP·L^-1) inhibited the seed germination and seedling growth of L. multiflorum. The contents of soluble protein, chlorophyll, GSH and ASC as well as the activities of SOD, POD and APX decreased, but the MDA content, production rates of H₂O₂ and O₂^-_·, and CAT activity increased. It was suggested that NO could promote the seed germination and seedling growth of L. multiflorum through increasing its seed amylase activity and seedling’s scavenging ability of reactive oxygen species.

Elements and configuration of ecological function network in typical cities of the Mainland and Taiwan

CHANG Hsiao-fei¹; WANG Yang-lin^1,2; LI Zheng-guo²

2007, 26(03):  399-405 . 

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Rapid urbanization accelerates the evolvement of urban landscape through urban function upgrading and spatial configuration renewing. However, the consequent eco-environmental problems, such as landscape fragmentation and heat island effect, have negative effects on the development of urban landscape. Therefore, the spatial optimization of urban landscape should take the economic and ecological needs into account, and propose ecological approaches for solving eco-environmental problems. Through analyzing the present status of the elements and configuration of urban ecosystem, the relationships among the elements were illuminated, aimed to protect the environment and promote the open spatial value of cities through optimizing urban framework. Taking Shenzhen of the Mainland and Wuxi of Taiwan, the two cities with stable economic development and well environment as study cases, their ecological function networks were evaluated by cost distance model, and the results showed that the urban ecological function networks in Shenzhen and Wuxi were significantly affected by urban development, with the location of their ecological center and economic center polarized obviously. The ecological center was far away from the transmission center, and the ecological functions flow and transmission had to depend more on the ecological components and unblocked structure within the areas of the cities. It was suggested that urban framework should be strengthened to promote urban ecological function, with the landscape units optimized and the key network nodes unblocked, which in turn could optimize urban landscape.

Dynamic assessment of ecological carrying capacity of Yellow River Basin in Qinghai Province

SUI Xin; QI Ye

2007, 26(03):  406-412 . 

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By using the methods of quantitative ecological carrying capacity (ECC) appraisal, the dynamic changes of the ECC of Yellow River Basin in Qinghai Province were investigated. The results showed that the ECC index decreased from 0.5096 in 1985 to 0.4700 in 1999, and would be 0.4263 in 2015. The ecosystem health in studied region was mostly at sub- or un-healthy level, and Huangshui Basin and the basins of Yellow River mainstream were at the lowest level. Among the sub-indices of ECC, the ecosystem health level corresponding to resources environmental carrying capacity was the highest. Human potential and ecological resilience were the two main factors affecting the ecosystem health of the studied region.

Eco-environmental sensitivity evaluation of Central Guizhou Province based on GIS technique

HE Qiu-hua¹; ZHANG Dan²; CHEN Zhao-meng¹; WANG Jing-song¹

2007, 26(03):  413-417 . 

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With the combination of geographical information system (GIS) and analytical hierarchy process (AHP), the eco-environmental sensitivity of Central Guizhou Province was evaluated comprehensively. A total of fifteen indices in 4 categories were selected to set up an indices system. The weight of each selected index and the value of each evaluation cell were calculated by AHP, and the eco-environmental sensitivity evaluation map was built by GIS. The spatial variation pattern of the sensitivity was analyzed from the aspects of soil erosion, rocky desertification, biodiversity, habitat and acid rain. The results indicated that in Central Guizhou, biodiversity and habitat had the highest sensitivity, followed by soil erosion and acid rain, and rocky desertification, which could provide a theoretical basis for the reasonable utilization of natural resources, layout of industry and agriculture, and sustainable development of this region.

Grade classification and annual case assessment of agro-meteorological disasters in Fujian Province

ZHANG Xing^1,2; ZHENG You-fei¹; ZHOU Le-zhao²

2007, 26(03):  418-421 . 

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Based on the statistic data of disaster-affected agricultural area in Fujian Province from 1985 to 2004, the affecting rates and variation values of the main agro-meteorological disasters including drought, flood, wind and hailstone damage, and cool and frost injury were calculated, and five grades were classified. Through grey correlation analysis, the correlation degree between the total disaster and each of the main disasters was worked out, and the weights of the affecting factors were obtained. An integrated assessment model was built to estimate the affecting degree of the disasters in the last 25 years, and the results showed that the appearance frequency of light and medium degree disasters was 88%. The most serious disasters happened in 1999, and the lightest ones were in 1984. The harmfulness of agro-meteorological disasters on agricultural production increased with time, and the fluctuation tended to be intensified.

Value evaluation of agricultural land resources in Wuhan

CAI Yin-ying; ZHANG An-lu

2007, 26(03):  422-427 . 

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In this paper, the market value and non-market value of different type agricultural land resources in Wuhan City were estimated by the methods of random sampling, income approach, and contingent valuation. The results showed that the total non-market value of agricultural land resources including cultivated land, horticultural land, forestland and water body was 57.712 billion Yuan, equivalent to 29.51% of the whole city’s GDP in 2004. Cultivated land had a total value of 105.698 billion Yuan, with its non-market value being 19.41% of the total. The total values of horticultural land and water body were 21.932 and 98.994 billion Yuan, and the proportion of their non-market value was 48.45% and 14.23%, respectively. Forestland had a non-market value of 12.472 billion Yuan in total, or 163236 Yuan per hectare.

Minirhizotron and radiocarbon methods: Their application and comparison in estimating fine root longevity

QUAN Xian-kui¹; YU Shui-qiang¹; SHI Jian-wei¹; YU Li-zhong²; WANG Zheng-quan¹

2007, 26(03):  428-434 . 

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The production and turnover of fine root plays an important role in terrestrial C- and nutrients cycling of terrestrial ecosystem, and is of significance in indicating global environmental changes. Fine root longevity is a key parameter in estimating fine root turnover, which determines the velocities of C- and nutrients consuming and cycling. However, the estimated longevity of fine root had a larger difference, owing to the discrepancy among the methods adopted.As for the newest estimation methods minirhizotron and radiocarbon (e . g . , bomb ¹⁴C, and FACE ¹³C), there was a 10 times more difference of estimated value between them. This paper introduced the principles and advantages of these two methods, and analyzed the reasons inducing such a difference of estimation results from the aspects of fine root heterogeneity, mortality pattern, and sampling errors, which would benefit the future study in this field.

Research progress on permafrost in cold region ecosystem

LU Jiu-jun^1,2; LI Xiu-zhen¹; HU Yuan-man¹; LIU Hong-juan^1,2; XIE Fu-ju^1,2;WANG Xian-wei^1,2; BING Long-fei^1,2

2007, 26(03):  435-442 . 

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Permafrost near earth surface is an important part of terrestrial ecosystem, and its research is a special concern of ecologists, hydrologists and engineers. Climate change plays a significant role on permafrost, being an indispensable part of the permafrost research at home and abroad. At the same time, the study on the hydrological and ecological effects of permafrost is developing. In China, the research on permafrost has a close link with the economic development in cold region, and admiring achievements have been obtained in the distribution, type, and degradation of permafrost, and especially in the exploitation of permafrost region. In the future, more attention should be paid on the permafrost mapping with high resolution and the thickness variation of permafrost active layer, and a long-term observation system on this variation should be established to better understand the response and feedback of terrestrial ecosystem to global climate change.

Effects of elevated CO₂ on soil microbes

JIA Xia¹; ZHAO Yong-hua²; HAN Shi-jie³

2007, 26(03):  443-448 . 

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A broad attention has been paid on the responses of soil microbial ecosystem to atmospheric CO₂ enrichment. In this paper, the effects of elevated CO₂ on soil microbial community structure, soil microflora, soil respiration, soil microbial biomass, and soil enzyme activities were summarized. Because of the differences in elevated CO₂ experimental system, test plants, and soil characteristics, no consistent conclusions were drawn, but the effects of elevated CO₂ on soil microbial ecosystem did exist.

Polycyclic aromatic hydrocarbons-degradation genes of microbes: A research review

ZHENG Le^1,2; LIU Wan¹; LI Pei-jun¹

2007, 26(03):  449-454 . 

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Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment, while microbial degradation is considered to be an essential approach in their decontamination. Many researches have been made on the pathways and metabolic intermediates of PAHs degradation. In general, low molecular weight PAHs can be degraded by microbes directly, while the microbial degradation of high molecular weight PAHs should be carried through by co-metabolism. In the last two decades, the PAHs-degradation genes of microbes were discovered consecutively, and their structure-function relationships were studied. This paper summarized the research advances in these fields, with the focus on the genes in the microbial degradation of naphthalene and phenanthrene, and discussed their application prospects.

Equiangular elliptic sector method, an improved approach to estimate forest gap size

HU Li-le^1,2; ZHU Jiao-jun¹; TAN Hui^1,2; YU Li-zhong¹; HU Zhi-bin^1,2; ZHANG Jin-xin¹

2007, 26(03):  455-460 . 

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Gap size is one of the important characteristics of forest gaps, and an important index for characterizing the light penetration and resource availability within forest gap. Therefore, it is of significance to measure gap size conveniently and accurately. One kind of the most commonly used methods in measuring gap size is to measure the distance from gap center to its edge along eight or sixteen compass directions, and then, estimate gap size approximately as a siogon. In this paper, this kind of method is called siogon methods (SMs), including equiangular octagon method (EOM), equiangular sixteen-gon method (ESM), and equiangular quadrangle method (EQM). Although EOM has less precision, it has been used more universally than ESM, because of its less time-consuming. Previous studies indicated that both EOM and ESM underestimated gap size, and thus, an improved approach was proposed in the present paper, i.e., using the same data sets to calculate the gap size approximating forest gap as 8 or 16 equiangular elliptic sectors. This improved method was named as equiangular elliptic sectors method (EES), which involved 8-equiangular elliptic sector (8-EES) and 16-equiangular elliptic sector (16-EES). Paired t-test indicated that the gap size estimated by ESM was significantly larger than that estimated by EOM and EQM, with an average of 10.96% and 61.66% increment respectively. The gap size estimated by 16-EES was significantly larger than that estimated by ESM, with an average of 1016% increment, while 8-EES had no significant difference with 16-EES, but had significant difference with EOM. Moreover, there was a significant difference between the gap size estimated by EOM with two data sets (the octagons were formed with eight different compass directions), but not for 8-EES. Therefore, it is recommended that gap size could be better estimated by 8-EES.