Table of Content

20 February 2009, Volume 20 Issue 02

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Articles

Effects of precipitation and interspecific competition on Quercus mongolica and Pinus koraiensis seedlings growth.

WU Jing-lian^1,2;WANG Miao¹;LIN Fei¹;HAO Zhan-qing¹;JI Lan-zhu¹;LIU Ya-qin³

2009, 20(02):  235-240 . 

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Aiming at the variation of precipitation pattern caused by global warming, a field simulation experiment was conducted to study the effects of 30% increase (+W) and decrease (-W) of precipitation on the morphology, growth, and biomass partitioning of mono- and mixed cultured seedlings of Quercus mongolica and Pinus koraiensis, the two dominant tree species in temperate broad-leaved Korean pine mixed forest in Changbai Mountains. Comparing with monoculture, mixed culture increased the canopy width and main root length of Q. mongolica seedlings, but decreased the basal diameter, plant height, leaf number, and dry masses of root, stem, leaf and whole plant of P. koraiensis seedlings significantly. Treatment （-W） increased the stem/mass ratio while decreased the main root length of Q. mongolica seedlings, and decreased the main root length, leaf number, dry masses of leaf and whole plant, and leaf/mass ratio, while increased the stem/mass ratio of P. koraiensis seedlings significantly, compared with treatment CK. Treatment (+W) had no significant effect on these indices of the two species. At early growth stage, interspecific competition and precipitation pattern had significant effects on the morphology and growth of the seedlings, and the responses were much stronger for P. koraiensis than for Q. mongolica.

Simulation of carbon stocks of forest ecosystems in Northeast China from 1981 to 2002.

ZHAO Jun-fang¹;YAN Xiao-dong²;JIA Gen-suo²

2009, 20(02):  241-249 . 

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Based on the forest carbon budget model for China FORCCHN, which had been improved through adding variables and modules of precipitation (rainfall and snowfall) intercepted by tree crown and of understory and litter, the spatiotemporal distribution pattern of carbon stocks of forest ecosystems in Northeast China from 1981 to 2002 were simulated. The results showed that from 1981 to 2002, the forest ecosystems in Northeast China played a role of carbon sink, and the total carbon stock was about 1237 Pg C·a-1, of which, the stock of vegetation and soil was 401 Pg C·a-1 and 836 Pg C·a-1, respectively. During the study period, the carbon stock of both vegetation and soil all had an increasing trend, and the increase of air temperature contributed more than the change of precipitation. Spatially, the carbon density of vegetation had the characteristics of high in southeast part and low in northwest part, with an average of 1045 kg C·m-2. Most of the forest ecosystems in Northeast China had a higher soil carbon density, with a mean value of 2178 kg C·m-2 and the maximum in part regions of Daxing’anling, Xiaoxing’anling, and Changbai mountains. The forest area in Northeast China accounted for 314 % of that in the whole country, possessing an important position in China forest carbon pool. The carbon stock of vegetation and soil in the forests of Northeast China occupied 7423 % and 6388 %, and the carbon density of vegetation and soil was 270 and 122 times of that in the forests of the whole country, respectively.

Competition intensity of Mongolian pine forests in Hulun Buir sand region of Inner Mongolia, China.

YU Hong;YANG Xiao-hui;CI Long-jun

2009, 20(02):  250-255 . 

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By using totally locating method and single tree competition index model, this paper studied the competition intensity of Mongolian pine forests in Hulun Buir sand region of Inner Mongolia, with the fire-disturbed Mongolian pine forest as a case. The results showed that within the same sampling plots, dead trees had the similar competition intensity, while the accompanying species in living and whole stems had two or three times higher competition intensity than Mongolian pine. The competition stress of Mongolian pine mainly came from intra-specific, and that of accompanying species mainly came from inter-specific. The competition intensity of living Mongolian pine was significantly lower in fire-disturbed than in undisturbed plot, and the competition intensity (CI) of living stems had a power functional relationship with their diameter at breast height (D), i.e., CI=AD-B. It was concluded that surface fire could significantly decrease the competition intensity among the stems, which would benefit the growth and development of living stems and the culture of the stems with larger diameter of breast height.

Seasonal variation of Cyclobalanopsis glauca whole-tree transpiration in karst region.

HUANG Yu-qing¹;ZHANG Zhong-feng¹;HE Cheng-xin¹;ZHAO Ping²;YUAN Wei-Yuan^1，3; JIAO Ji-fei^1,3;YOU Ye-min^1,3

2009, 20(02):  256-264 . 

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By using Granier’s sap-flow method, the variations of sap flux density and whole-tree transpiration of Cyclobalanopsis glauca (syn. Quercus glauca) on a hilly slope in the karst region of South China were studied, with their driving factors analyzed. The sap flux density (Js) of C. glauca varied randomly with the diameter of breast height of individual trees, and its maximum occurred at 13：30〖KG-*2〗-〖KG-*7〗14:30. In a seasonal course, the daily Js was the maximum (5600 g H2O·m -2·s-1) in summer, and the minimum (3586 g H2O·m-2·s-1) in spring. The daily whole-tree transpiration had a greater change with weather condition, representing a power functional relationship with vapor pressure deficit (VPD) and photosynthesically active radiation (PAR) (R=097，P<001). The average daily whole-tree transpiration tended to be high in summer and low in winter and spring, and decreased with the decrease of soil moisture content in autumn (drought season). However, comparing with that of the tree species in other regions, the daily whole-tree transpiration amount of C. glauca in study region was still higher, even though the weather was dry and the soil was thin. It was presumed that in the dry season in karst region, the water supply for C. glauca could be mainly depended on the water-rich epikarst.

Effects of human disturbance on coarse woody debris of Larix gmelinii forest on northern slope of Greater Hinggan Mountains.

GU Hui-yan;JIN Jing-bo;CHEN Xiang-wei;WANG En-heng;ZHOU Yi-yang;CHAI Ya-fan

2009, 20(02):  265-270 . 

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An investigation was conducted on the living tree volume, coarse woody debris (CWD) loading, and composition of Larix gmelinii forest along a human disturbance gradient, i.e., no disturbance (natural larch forest), one-time d isturbance (natural forest was disturbed once only), and two-time disturbance (natural forest was disturbed two times consecutively), on the northern slope of Greater Hinggan Mountains. The results showed that under no disturbance, one -time disturbance, and two-time disturbance, the average living tree volume of L. gmelinii forest was 1616, 1383, and 1148 m3·hm-2, and the average CWD loading was 6977, 3664 and 3261 m3·hm-2, respectively . In natural L. gmelinii forest, most of CWD was of 20〖KG-*2〗-〖KG-*7〗40 c m diameter class, among which, fallen logs occupied 72%, and snags and stumps oc cupied 28%; while in one-time and two-time disturbance L. gmelinii forests, most CWD was of 10〖KG-*2〗-〖KG-*7〗30 cm diameter class, with the fallen logs , snags, and stumps occupied 70%, 14% and 16%, and 57%, 15% and 28%, respectivel y. Human disturbance reduced the CWD loading of L. gmelinii forest and altere d the composition of the CWD.

Chlorophyll content and net photosynthetic rate of Machilus pauhoi and M.leptophylla.

ZHONG Quan-lin¹;CHENG Dong-liang¹;HU Song-zhu²; HE Li-zhong³; TANG Cheng-cai¹;WEN Ya-xiang¹;QIU Jian-fei¹;LI Xiu-hua¹

2009, 20(02):  271-276 . 

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By using SPAD-502 chlorophyll meter, LI-6400 portable photosynthesis system, and spectrophotometer, the leaf SPAD value, net photosynthetic rate ( Pn), and chlorophyll (a+b) content (Ct) of 3-year-old Machilus pauhoi and M. leptophylla seedlings were measured, and the relationships of SPAD value with Pn and Ct were analyzed. The M. pauhoi seedlings were grown from the seeds originated from Suichuan County of Jiangxi Province and Ji an’ou County of Fujian Province, named as MPS and MPJ, respectively; while the M. leptophylla seedlings were grown from the seeds originated from Shangyou County of Jiangxi Province, named as MLG. There were significant differences in the mean chlorophyll content of MPS, MPJ, and MLG. The SPAD value and the conten ts of chlorophyll (a+b) (Ct), chlorophyll a (Ca) and chlorophyll b (Cb) we re in the order of MPS<MLG<MPJ, with the mean SPAD value being 4380, 4512, and 5067 and the Ct value being 1944, 2831, and 3447 mg·g-1 , respectively. The chlorophyll content was influenced by the maturing degree of meso phyll tissues of M. pauhoi and M. leptophylla, being lower in current-year le aves than in 2-year-old leaves. The Ct of same age leaves at different c rown layers of MPS and MPJ and of MLG was in the order of upper layer<middle la yer<lower layer and of upper layer<lower layer<middle layer, respectiv ely, and the SPAD value of the same lamina at different positions was in the ord er of apex<middle<base. SPAD value had a significant positive linear correla tion with Ct, and a statistically not significant positive correlation wit h Pn.

Nitrogen accumulation and allocation in Calamagrostis angusifolia in different plant communities of Sanjiang Plain.

SUN Zhi-gao^1,2;LIU Jing-shuang²;YU Jun-bao¹

2009, 20(02):  277-284 . 

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From May to October in 2004, the characteristics of nitrogen (N) accumula tion and allocation in Calamagrostis angustifolia, the dominant species in t he typical meadow and marsh meadow communities of Sanjiang Plain, were studied. The results showed that the total nitrogen (TN) content in the aboveground organ s and litters of typical meadow C. angustifolia (TMC) and marsh meadow C. angustifolia (MMC) decreased during growth season, which could be described by exponential decay model (TN=Aexp(-t/B1)+B2,R2≥094). The TN content in TMC and MMC roots fluctuated greatly, and a significant N accumula tion period (15〖KG-*2〗-〖KG-*7〗30 d) was observed before the coming of growth midseason. The N accumulation amount and rate of different organs and litters h ad obvious seasonal changes, and their values of the aboveground organs were muc h higher for TMC than for MMC， while the values of the roots were in adverse. The N allocation ratio of different parts of TMC and MMC also had significant diffe rences. Root was the important N storage, and the root N allocation ratio of TMC and MMC was (5938±1286)% and (8458±338)%, respectively. Among the abo veground parts, leaf had the highest N allocation ratio, being (2428±1209)% for TMC and (818±332)% for MMC. The change patterns of the N allocation ra tio of aboveground and underground parts were just in adverse, which reflected t he osculation contact in N supplement aspect. The annual N absorption amount and maximum standing crop of TMC and MMC were 2302， 3630 g·m-2,and 2818， 5143 g·m-2, respectively. The N absorption coefficient and ut ilization coefficient of TMC were much higher than those of MMC (0017 and 0634 relative to 0015 and 0548, respectively), illustrating that TMC had higher capability of N absorption and utilization than MMC.

Responses of subalpine meadow Poa botryoides to climate change.

YAO Yu-bi^1,2,3;ZHANG Xiu-yun³;WANG Run-yuan¹;AN Hua-yin⁴

2009, 20(02):  285-292 . 

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Based on the field plot observation and related meteorological data, the effects of climate change in 1985〖KG-*2〗-〖KG-*7〗2005 on the growth and development o f subalpine meadow Poa botryoides in Maqu County of Gansu Province were analyzed . The results showed that during study period, the annual precipitation in the Maqu County had a decreasing tr〖JP2〗end, with a rate of -9895 mm·(10 a)-1 and a cyc le of 3 years, while the annual air temperature had an increasing trend, with a rate of 0341 ℃·(10 a)-1. The aridity index of P. botryoides in grow th season had an obvious increasing trend, with a rate of 0036 ·(10 a)-1 , and the tendency was more markedly from the beginning of the 1990s to 2005. The pe riod from reviving to ripeness of P. botryoides was 140〖KG-*2〗-〖KG-*7〗150 d, and the requirements of accumulated temperature above 0 ℃, precipitation, a nd sunshine duration in this period were 1000 ℃〖KG-*2〗-〖KG-*7〗1200 ℃, 400〖KG-*2〗-〖KG-*7〗450 mm, and 1000〖KG-*2〗-〖KG-*7〗1100 h, respectively . The growth rate of P. botryoides turned to higher at 54 d after reviving, reached the highest at 80 d after reviving, and became lower at 104 d after revi ving. Under the effects of climate warming, the phenophase of P. botryoides was advanced by 15 d·(10 a)-1 at heading stage, 7〖KG-*2〗-〖KG-*7〗8 d·(1 0 a)-1 at flowering stage, 8〖KG-*2〗-〖KG-*7〗9 d·(10 a)-1 at ripenes s stage, and 3 d·(10 a)-1 at withering stage. Climate change made the P. botryoides yield in study area have greater variation and higher unsteadiness.

Influence of salt marsh vegetation on spatial distribution of soil carbon and nitrogen in Yancheng coastal wetland.

MAO zhi-gang;WANG guo-xiang;LIU jin-e;REN li-juan

2009, 20(02):  293-297 . 

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Soil samples under different salt marsh vegetations in Yancheng coasta l wetland were collected, and their organic carbon (C) and total nitrogen (N) we re determined, aimed to analyze the influence of salt marsh vegetation on the sp atial distribution of soil carbon and nitrogen. The results showed that the orga nic C and total N contents in top soils varied from 171 to 792 g·kg-1 and from 017 to 036 g·kg-1, respectively, and there were significant differences among different vegetation zones. The top soils organic C and total N contents in vegetation zones were higher than those in mudflat without vegeta tion. In the soil profiles in vegetation zones, organic C and total N contents h ad a trend of decreasing with depth, but changed little below the depth of 15 cm . Soil organic C was significantly positively correlated with soil total N and C /N, but soil total N had no significant correlation with soil C/N.

Species composition and spatial structure of plants in urban parks of Beijing.

ZHAO Juan-juan;OUYANG Zhi-yun;ZHENG Hua;XU Wei-hua;WANG Xiao-ke

2009, 20(02):  298-306 . 

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By the method of stratified random sampling, the species composition and spatial structure of the plants in 53 parks in Beijing urban area were investigated, aimed to provide basic information for the protection of plant diversity in the parks and the management of the parks. A total of 492 plant species belong to 96 families and 283 genera were recorded. Based on the data of 21 investigation items about the trees, shrubs, and grasses in the study area and related statistical analyses, the plant structural patterns commonly seen in the green space of the parks of Beijing urban area were introduced. Among the plants in the parks, native species occupied 5386% of the total. The chorological composition of the genera embraced broad kinds of geographical elements in China, and the predominance of dominant plants was remarkable. In most green patches of the parks, herbaceous species were more abundant and had higher coverage, shrubs had relatively low coverage and were less beneath tree canopy, and trees and shrubs had lower species richness and density. The canopy breadth and the diameter of breast height of trees as well as the breadth of shrubs and the heights of trees and shrubs were basically at the second grade, but the canopy structure of the trees were better, with good conditions of sunlight and growth. The crown missing of the shrubs was relatively low. It was suggested from correlation analyses and document survey of Beijing parks construction history that park landscape design, alien species introduction, and cultivation management were the main factors affecting the species composition and spatial structure of the plants in Beijing urban parks.

Crop root growth and water uptake in maize/soybean strip intercropping.

GAO Yang;Duan Ai-wang;LIU Zhan-dong;WANG He-zhou;CHEN Jin-ping;LIU An-neng

2009, 20(02):  307-313 . 

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A field experiment was conducted to study the root distribution and water adsorption of maize and soybean in their strip intercropping. The results showed that under the condition of full irrigation, both maize roots and soybean roots were distributed approximately in triangle-shape in soil profile. Maize roots extended horizontally into a wider area, 58 cm away from the plant row and usually occurred in 16〖KG-*2〗-〖KG-*7〗22 cm soil layer. They were not restricted to maize root zone, but traversed into soybean strip zone. Soybean roots were horizontally distributed in a limited zone near the plant row, and their reached range was within about 26 cm. Both for maize and for soybean, their root mass density decreased with increasing distance from the plant row. About 90% of the root mass of maize and edge-row soybean was presented in 0〖KG-*2〗-〖KG-*7〗30 cm soil layer. The root mass density of maize at 10 cm from maize row was greater than that of soybean, but this density of soybean at 20 cm from maize strip was greater than that of maize. About 85% of root mass was distributed in 0〖KG-*2〗-〖KG-*7〗30 cm soil layer, and the variation of soil water content in intercropping strips also occurred mainly in this soil layer. In the maize/soybean strip intercropping system, soil water content decreased in the order of maize zone>soybean zone>middle zone, indicating that each strip-intercropped crop preferentially absorbed the soil water in its strip and utilized the soil water in intermingled zone later.

Effects of fertilization on carbon/nitrogen ratio of maize straw and its mineralization in soil.

CHEN Xing-li;ZHOU Jian-bin;LIU Jian-liang;GAO Zhong-xia;YANG Xue-yun

2009, 20(02):  314-319 . 

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Maize straws were collected from different treatments of two long-term fertilization studies, their carbon (C) / nitrogen (N) ratios were determined, and their C and N mineralization rates in soil were compared in an aerobic incubation test. The results showed that comparing with no fertilization, applying chemical fertilizers (NPK) or chemical fertilizers plus manure (MNPK) increased the N content and decreased the C/N ratio of maize straw. The amounts of mineralized and immobilized C and N of the straws from different fertilization treatments differed with incubation time. The straws from treatments NPK, MNPK, and N240 had significantly higher C mineralization rates than that from the treatment without fertilization. After incubation for 60 days, the straw from treatment NPK had the highest C mineralization rate (1324% of added organic C), and the immobilized N from the straws of fertilized plots, especially of MNPK plot, was lesser, compared to unfertilized plots. Adding maize straw into soil increased the metabolic quotient (qCO2) of soil microorganisms, but the difference among the treatments was not significant. During incubation, the amounts of soil microbial biomass C and N from different treatments differed with time. Therefore, in agricultural practices, the differences in the nutrient contents of straw due to different fertilization should be considered when the straw was to be added into soil.

Responses of rice genotypes with different silicon uptake efficiency to different silicon supply.

LIU Hui;ZHANG Jing;DU Yan-xiu;ZHAO Quan-zhi;CHEN Jing-rui;QIAO Jiang-fang

2009, 20(02):  320-324 . 

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To understand the effects of silicon on the growth and development of rice roots, a hydroponic experiment with 3 levels of silicon, i.e., no silicon (T1), 125 mmol silicon·L-1 (T2), and 2 mmol silicon·L-1 (T3), was conducted, using rice cultivars TN1 and Baixiangjing with high silicon uptake efficiency and Juanyejing and Hitomebore with low silicon uptake efficiency as test materials. The results showed that with the increase of silicon supply, the root dry mass, root-shoot ratio, lateral root number, and total root length of all test rice cultivars decreased, while the dry mass of above-ground parts, root number, and root diameter increased. Relatively higher silicon supply was beneficial to the differentiation and development of indefinite roots, but not favorable to the lateral roots. Under lower silicon supply, the root dry mass and root-shoot ratio of TN1 and Baixiangjing were significantly higher than those of Juanyejing and Hitomebore. Furthermore, the number of lateral roots and the total root length of Baixiangjing were also significantly higher than those of Juanyejing and Hitomebore. It was concluded that total root length and lateral root number were the main factors affecting rice silicon uptake efficiency.

Effects of applying inorganic P and wheat straw on the microbial biomass P and microbial P concentration in a calcareous soil with low concentration available P .

ZHAO Xiao-rong¹;ZHOU Ran^1,2;LI Gui-tong¹;LIN Qi-mei¹

2009, 20(02):  325-330 . 

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In an incubation test, a calcareous soil with low concentration of ava ilable P was amended with KH2PO4 (0, 25, 50, and 100 mg P·kg-1) and g round wheat straw (5 g C·kg-1), and incubated at 25 ℃ for 90 days. The aim was to investigate the change patterns of soil microbial biomass P and microbial P concentration as well as their relationships with soil available P. The results showed that both soil microbial biomass P and microbial P concentration increased with increasing inorganic P addition, with the maximum being 7137 and 10534 mg·kg-1, respectively. The combine d application of inorganic P (except 100 mg P·kg-1) and wheat straw decre ased the soil microbial biomass P and microbial P concentration, being most obvi ous at early incubation period. Soil microbial biomass P and microbial P concent ration had significant positive correlations (P<005) with soil available P (R2=026 and 040, n=49, respectively). The applied P could rapidly transform into microbial biomass P. The maximum apparent contribution rate of applied P to microbial biomass P was 71%. The added wheat straw could further improve the appar ent contribution rate.

Soil soluble organic nitrogen in different horticultural production systems.

GE Ti-da^1,2;TANG Dong-mei¹;SONG Shi-wei¹; HUANG Dan-feng¹

2009, 20(02):  331-336 . 

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By using ultra-centrifugal technique and KCl extraction, the contents of soil soluble organic nitrogen (SON), dissolved organic nitrogen (DON), and f ree amino acid (FAA) in three horticultural production systems, i.e., organic (O S), transitional (TS), and conventional (CS), were determined, and their correla tions with some other soil properties were investigated. The results showed that SON content in the three production systems was in the order of OS>CS>TS, and t he ratios of SON to soil total soluble N (TSN) and total N (TN) in OS, CS, and T S were 429%, 245%, and 184%, and 111%, 119%, and 74%, respectively. T he DON content in OS, TS and CS was 438, 168 and 326 mg·kg-1, occup ying 479%, 221% and 261% of TSN, and 29%, 23% and 36% of TN, respect ively. FAA content occupied 1%〖KG-*2〗-〖KG-*7〗3% of TSN and 2%〖KG-*2〗-〖KG- *7〗10% of SON, and decreased in the order of CS>TS>OS. Correlation analysis sho wed that TSN, SON and FAA were significantly correlated with soil total N, total carbon, NO3--N and NH4+-N. Different management measures of horticult ural production system changed the SON content and its characters.

Optical properties and remote sensing retrieval model of diffuse attenuation coefficient of Taihu Lake water body.

LE Cheng-feng¹;LI Yun-mei¹;ZHA Yong¹;SUN De-yong¹;WANG Li-zhen¹;He Jun-liang²

2009, 20(02):  337-343 . 

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The spectral and chemical analytical data of Taihu Lake water quality in Nov. 8〖KG-*2〗-〖KG-*7〗22, 2007 were used to analyze the spectral characteristics of dif fuse attenuation coefficient (Kd) of the water body in autumn and related affecting factors. On the basis of this analysis, the Kd at band 490 nm, Kd(490), was used as a variable to build the relationship between Kd and remote sensing reflectance. The results indicated that within the scope of visible band, the Kd of the water body at most locations of Taihu Lake pre sented an exponent decreasing trend with the increase of wave length. Due to the higher concentration of phytoplankton in some locations, a peak value of K d was presented at band 675 nm. Non-organic suspended particles, because of t heir higher content in suspended sediment, had larger effects on Kd than o rganic suspended ones. There was a good correlation between Kd and remote sensing reflectance. Taking Rrs(550), Rrs(675) and R rs(731) as independent variables and doing regression analysis with Kd(4 90), a good linear relationship was found between Kd(490) and Rrs (731), and multi-variate linear regression analysis using variables R rs(550), Rrs(675) and Rrs(731) could get better effect ( R2>096) than the regression analysis using variable Rrs(731).

Functional groups of high trophic level communities in adjacent waters of Changjiang estuary.

ZHANG Bo;JIN Xian-shi;TANG Qi-sheng

2009, 20(02):  344-351 . 

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Based on the three bottom trawl surveys in adjacent waters of Changjiang estuary in June, August and October 2006, the composition and variation of the functional groups of high trophic level communities in the waters were studied. According to diet analysis, the high trophic level communities in the waters included six functional groups, i.e., piscivore, shrimp predator, crab predator, benthivore, planktivore, and generalist predator. Due to the variation of marine environment and fish migration behavior, the composition and trophic level of the high trophic level communities had greater monthly change. In June, fishes, acetes, and crabs dominated the communities, and planktivore was the major functional group, with its trophic level being the lowest (306); in August, fishes were dominant, and shrimp predator was the major functional group, with its trophic level being the highest (378); and in October, fishes also dominated the communities, the proportion of shrimp and crab increased, and planktivore and benthivore were the major functional groups, with a trophic level of 358.

Effects of nonylphenol on proliferation and anti-oxidative functions of Carassius auratus primary culture hepatecytes.

ZHANG Yi;ZHANG Gao-feng;WEI Hua

2009, 20(02):  352-357 . 

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The study on the proliferation and anti-oxidative functions of Cara ssius auratus primary culture hepatecytes under effects of different concentra tion nonylphenol showed that at all test concentrations of nonylphenol, the prol iferation of the hepatecytes was inhibited. High concentration (10-3 mol· L-1) nonylphenol had significant inhibitory effect, and induced an apparen t morphological alteration of the hepatecytes. Nonylphenol upset the balance of hepatecytes anti-oxidative system through decreasing the activities of superoxi de dismutase (SOD) and catalase (CAT) while increasing the hydroxyl free radical concentration. Nonylphenol also caused the oxidative damage on the hepatecytes, resulting in the increase of malondialdehyde (MDA) concentration in cell cultur e medium. The nonylphenol-induced oxidative stress engendered a series of in vi tro toxic effects on the primary culture hepatecytes of C. auratus.

Effects of initial feeding on the growth, survival, and body biochemical composition of Siberian sturgeon (Acipenser baerii) larvae.

ZHANG Tao¹;ZHUANG Ping¹;ZHANG Long-zhen¹;WANG Bin²;GAO Lu-jiao¹; XIA Yong-tao²;TIAN Mei-ping^1,3

2009, 20(02):  358-362 . 

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Siberian sturgeon (Acipenser baerii) larvae were raised with Lim nodrilus sp., Artemia nauplii, Moina sp., and artificial commercial di et for 30 days to investigate the effects of different initial feeding diets on the growth, survival, and body biochemical composition of the larvae. The results showed that A. nauplii was the best initial feeding diet, with the survival rate of A. baerii larvae being significant higher (9667%) than the others. Feeding with Limnodrilus sp. gave the highest growth rate of A. baerii larvae, while fee ding with artificial commercial diet gave the lowest efficiency on the growth ra te and survival rate of the larvae. The larvae raised with different diets had s ignificantly different body biochemical composition. After fed with artificial c ommercial diet, the larvae had the highest moisture content but the lowest crude protein and crude ash contents. Taking A. nauplii as the initial feeding d iet and then feeding with Limnodrilus sp. could gave the ideal growth and survival rates of A. baerii larvae.

Diversity and niche of soil moniliaceous hyphomycetes in Taibai Mountain.

PAN Hao-qin;ZHANG Tian-yu;HUANG Yue-hua;XIA Hai-bo;YU Jin-feng

2009, 20(02):  363-369 . 

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Sixteen genera of soil moniliaceous hyphomycetes were isolated from 40 soil samples collected from the southern and northern slopes of Taibai Mountain , and the indices Shannon-Wiener diversity index, evenness, niche breadth, and niche overlap were used to analyze the community structure and niche of soil mon iliaceous hyphomycetes in different forest types on the southern and northern sl opes of Taibai Mountain. The results showed that the distribution of soil monili aceous hyphomycetes on the study area had an obvious environmental gradient patt ern. Altitude and forest type were the main determinants of the fungal community distribution. The species richness and diversity index of soil moniliaceous hyp homycetes decreased significantly with increasing altitude, but the community ev enness represented an increasing trend. Among the genera of soil moniliaceous hy phomycetes, Penicillium, Aspergillus, Verticillium, Paecilomyces and Acrem onium had larger niche width and greater niche overlap with other genera, sugg eting that these genera had wide distribution on the southern and northern slope s of Taibai Mountain. As for Trichothecium, Gliocladium and Metarhizium, their niche width was narrower, and their niche overlap with other genera was s maller, indicating that the distribution of these genera was more affected by al titude and vegetation, with the occurrence only in special forest types.

Effects of food concentration on life history traits of Brachionus calyciflorus clones in Jinghu Lake.

DONG Li-li^1,2;XI Yi-long¹;ZHANG Lei¹

2009, 20(02):  370-375 . 

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Four Brachionus calyciflorus clones (clone A, B, C, and D) different i n biochemical and genetic characteristics were collected from Jinghu Lake in sum mer, and their life history traits were studied at 25 ℃ under the conditions of feeding with 10×106, 20×106, 40×106 and 80×106 cells·L -1 of Scenedesmus obliquus. The results showed that S. obliquus concen tration had different effects on the survival rate and fecundity of different B. calyciflorus clones. Among the four clones, clone C had the shortest gene ration time, clone B had the longest generation time, life expectancy and averag e lifespan, and clone A had the highest percentage of mictic females in its offs pring. No significant differences were observed in the net reproductive rate and individual fitness among the four clones. At 20×106 cells·L-1 of S. obliquus, the net reproductive rate of B. calyciflorus was the lowest ; at 10×106 cells·L-1 of S. obliquus, B. calyciflorus had the sh ortest average lifespan and life expectancy but the highest mictic rate in its o ffspring; at 80×106 cells·L-1 of S. obliquus, B. calyciflorus ha d the highest intrinsic rate of population increase and the longest average life span and life expectancy; and at 40 and 80×106 cells·L-1 of S. obliquus, the individual fitness of B. calyciflorus was the highest. Clone C had the smallest individual fitness at 39×106 cells·L-1 of S. obliquus and clone D had the highest one at 634×106 cells·L-1 of S. obliquus, while the individual fitness of clones A and B was not corr elated with S. obliquus concentration. After July, the disappearance of gene tically different B. calyciflorus clones from Jinghu Lake might attribute to the va riation of algal food concentration, and the similar individual fitness of the four clones might be one of the reasons that contribute to the c oexistence of B. calyciflorus clones in Jinghu Lake in summer.

Distribution of Formica cunicularia mound and related affecting factors on mobile dune in Horqin sandy land.

LIU Ren-tao;ZHAO Ha-lin;ZHAO Xue-yong

2009, 20(02):  376-380 . 

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Taking the typical mobile dune in Horqin sandy land as test object, th e density, diameter, and coverage of Formica cunicularia mounds on different land forms were investigated by quadrate method, with the spatial distribution of F. cunicularia mounds and the effects of topography and soil property on F. cunicularia nest-building activities discussed. The results showed that the density of F. cunicularia mounds decreased in the order of ridge>leewar d slope>windward slope, while the diameter and coverage of the mounds were in t he order of ridge>windward slope>leeward slope and conditioned by mound densit y. The spatial distribution of F. cunicularia mounds was in random pattern. Topography and soil property co-affected the nest-building activities of F. cunicularia.

Population life parameters and relative fitness of alpharmethrin-resistant Bactrocera dorsalis strain.

ZHANG Yu-ping^1,2;LU Yong-yue¹;ZENG Ling¹;LIANG Guang-wen¹

2009, 20(02):  381-386 . 

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Based on the observation of the development and reproduction of experi mental populations of alpharmethrin-resistant and susceptible Bactrocera dor salis strains at (28±2) ℃, the life tables of the populations were establish ed, and the differences in the relative ecological fitness of the two strains wa s analyzed. The results showed that comparing with alpharmethrin-susceptible B. dorsalis strain, the resistant one had longer durations of development st ages, average generation, and previposition, its fecundity was not stable and lo wer, and the hatch of eggs and the emergence of adults were depressed. The fecun dity of the susceptible and resistant strains was 3240 and 2407, respectivel y. Based on the life tables, the population trend index (I) of resistant str ain was 7910, while that of susceptible strain was 11697. The net reproducti on rate (R0) and the intrinsic rate of increase (rm) of resistant st rain were 141400 and 79463, while those of susceptible strain were 218400 and 83809, respectively. The relation fitness of resistant strain was only 06474. All of the results revealed that the resistant strain was at an obvious inferior position of reproduction and development.

Effects of land use type on diurnal dynamics of environment microclimate in Karst zone.

LI Sheng¹;REN Hua-dong¹;YAO Xiao-hua¹;ZHANG Shou-gong²

2009, 20(02):  387-395 . 

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In June 2007, the diurnal dynamics of light intensity, air temperature , air relative humidity, soil temperature, and surface soil (0〖KG-*2〗-〖KG-*7 〗5 cm) water content of five land use types in the typical Karst zone of Lingyu n City in Guangxi Zhuang Autonomous Region were observed. The results showed tha t different land use types altered the composition, coverage, and height of abov eground vegetation, which in turn changed the environment microclimate to differ ent degree. The microclimate quality was in the order of forestland>shrub land>g rassland>farmland>rock land. On rock land, the light intensity, air temperature, air relative humidity, soil temperature, and soil water content were higher, an d the diurnal variation of the five climatic factors was notable, with the micro climatic conditions changed towards drier and hotter. Compared with those on roc k land, the light intensity on forestland, shrub land, grassland, and farmland d ecreased by 964%, 520%, 170% and 442%, air temperature decreased by 30 1%, 202%, 127% and 178%, air relative humidity increased by 1292%, 572 %, 180% and 412%, soil temperature decreased by 115%, 8%, 25% and 55%, and soil water content increased by 426%, 332%, 157% and 140%, respecti vely. The five climatic factors on forestland and shrub land had lesser fluctuat ion, with the microclimate tended to cool and wet. Light intensity, air temperat ure, and soil temperature correlated positively with each other, and had negativ e correlations with air relative humidity and soil water content. A positive cor relation was observed between air temperature and soil water content.

Simulation model on barley yield formation.

ZOU Wei^1,3;LIU Tie-mei²;KONG De-yan¹;TANG Liang¹;CAO Wei-xing¹

2009, 20(02):  396-402 . 

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By the method of yield component, a simulation model on barley yield f ormation was established, which could be available for different barley cultivar s in different areas. The establishment process of the model was as the followin g. With the yield components of different cultivars under optimal conditions in Wuhan, Yangzhou, and Kunming as the bases, the regression equations of the relat ive values of ears per plant, kernels per ears, and thousand-grain weight with the accumulated photosynthetic effective radiation (∑PAR) were established, and the functional relations between the ears per plant, kernels per ears, and thou sand-grain weight under actual conditions as well as their potential values und er optimal conditions and the variables soil moisture regime and nutrient conten ts under actual conditions were formed. The model more comprehensively considere d the internal and external factors of barley growth and development. The intern al factors reflecting the genetic properties of cultivar included potential ears per plant, potential kernels per ear, potential thousand grain weight, and grai n-filling duration; while the external factors included ∑PAR and soil moistur e regime and nutrient contents. Field experiments with different barley cultivar s at different sowing dates were conducted in Wuhan, Kunming, and Yangzhou, and the data obtained were used to calibrate and validate the model. The results sho wed that the model better simulated the yield components and theoretical yield, with the average absolute values of relative error (RE) of ears per plant, kerne ls per ear, and thousand-grain weight being 196%, 188% and 167%, respe ctively. The correlation coefficient from y=x regression analysis on the sim ulated and observed values of the three yield components and theoretical yield w as between 09464 and 09987, indicating that this model was more predictab le and applicable.

Dynamics of plant community species diversity in the process of ecological rehabilitation in north Shaanxi loess area.

QIN Wei;ZHU Qing-ke;ZHANG Yu-qing;ZHAO Lei-lei

2009, 20(02):  403-409 . 

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Based on the vegetation survey on 18 sampling plots in Wuqi County of Shaanxi Province, and by using the methods of substituting space series for time series and of contrastive analysis, the dynamics of plant community species diversity in the process of ecological rehabilitation in the County was analyzed from the aspects of succession time, rehabilitation mode, and slope direction. The results showed that in the 25 years natural succession series, the natural restoration community on previous cropland experienced the sequence of Salsola collina, Artemisia scoparia, Lespedeza davurica, Artemisia sacrorum, and Bothriochloa ischcemum, with the dominant species tended to be changed from annual to perennial and from low-class to high-class. The variations of species number, Margalef index, Simpson index, Shannon-Wiener index, and Pielou index in the succession process could all be described by a quadratic function y = at2 + bt + c, suggesting that after the outside pressure removed, the degraded ecosystem in loess area could naturally restore to an advanced and steady state, but the restoration rate would be very slow. With the same site factors and restoration periods, the Margalef index, Shannon-Wiener index and Pielou index of herb layer decreased in the order of naturally restoring on previous cropland (Ⅰ)＞converting cropland to grassland (Ⅱ)＞converting cropland to forestland (Ⅲ)＞afforestation on barren hills (Ⅳ), while Simpson index changed in adverse. Comparing with natural restoration, the community types of herb layer in Ⅱ and Ⅲ were at the more advanced stage of natural succession series though the species diversity index was lower, indicating that artificial planting would accelerate the succession process. In the same period of rehabilitation, the Margalef index, Shannon-Wiener index and Pielou index of natural restoration community were obviously higher on shady slope than on sunny slope, and the community type was at the more advanced stage of natural succession series, suggesting that the basic ecological rehabilitation condition on sunny slope was worse, and the succession rate was slower.

Strategic environmental assessment on land use programming of Shaya County, Xinjiang Uygur Automous Region.

ZHANG Fei;TASHPOLAT Tiyip;DING Jian-li;TIAN Yuan;MAMAT Sawut

2009, 20(02):  410-416 . 

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With the establishment and implement of national and regional land use programming, to approach the technology and methodology of environmental assessment appropriate for the overall land use programming is of great significance. By using the theories of strategic environmental assessment and taking ecosystem services value as an evaluation index, a comprehensive assessment on the potential eco-environmental effects of 1996〖KG-*2〗-〖KG-*7〗2010 land use programming of Shaya County in Xinjiang Uygur Automous Region was made. The results showed that from 1996 to 2010, the total ecosystem services value of the County increased from 6933×108 Yuan to 7081×108 Yuan, with an annual increment of 015%, which suggested that this programming was basically reasonable. However, the common land expansion should be controlled strictly. The increase rate of eco-value was higher than that of GDP, indicating that Shaya County was of eco-value gaining. There were still some shortages in the programming, e. g., the area ratio of unutilized land (desert) would be 8395% in 2010, and thus, the programming should be emended to increase the eco-benefit of land use.

Evaluation of economic forest ecosystem services in China.

WANG Bing¹;LU Shao-wei²

2009, 20(02):  417-425 . 

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This paper quantitatively evaluated the economic forest ecosystem services in the provinces of China in 2003, based on the long-term and continuous observations of economic forest ecosystems in this country, the sixth China national forest resources inventory data, and the price parameter data from the authorities in the world, and by applying the law of market value, the method of substitution of the expenses, and the law of the shadow project. The results showed that in 2003, the total value of economic forest ecosystem services in China was 1176339×108 yuan, and the total value of the products from economic forests occupied 193% of the total ecosystem services value, which indicated that the economic forests not only provided society direct products, but also exhibited enormous eco-economic value. The service value of the functions of economic forests was in the order of water storage > C fixation and O2 release >biodiversity conservation > erosion control > air quality purification> nutrient cycle. The spatial pattern of economic forest ecosystem services in the provinces of China had the same trend with the spatial distribution of water and heat resources and biodiversity. To understand the differences of economic forest ecosystem services in the provinces of China was of significance in alternating the irrational arrangement of our present forestry production, diminishing the abuses of forest management, and establishing high grade, high efficient, and modernized economic forests.

Grain for Green Project: Willingness evaluation of the farmers in northern Shaanxi Province of China.

CAO Shi-xiong¹;CHEN Li²;YU Xin-xiao¹

2009, 20(02):  426-434 . 

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To understand the social-economic effects of the policies about ecolo gical restoration in northern Shaanxi Province of China, an investigation to the farmers was made in 2007 about the effects of Grain for Green Project (GGP) on their livelihoods, and the concerns raised by this Project. Most farmers appreci ated the compensation policy of GGP, but a few of them (89% and 22%, respect ively) considered the planting of trees and of forage species to be a priority. Although only 191% of the farmers felt that their livelihoods were adversely a ffected by the GGP and 638% of the farmers supported the project, a large prop ortion (372%) still planned to return to cultivating forested areas and grassl and, once the project was over. Therefore, the vegetations restored by the Proje ct were at the risk of being converted once more into farmland and rangeland whe n the Project’s subsidies ended, compromising the sustainability of the Project’s environmental achievements. For the success of the programs about environment al restoration, the GGP should give rational compensation to the farmers for the ir costs, make technical progress to increase the output of per unit land, and c reate jobs and training programs to transfer the rural surplus labor.

Influence of fungi-feeding nematodes on soil functional stability under heat or copper stress.

CHEN Shi;CHEN Xiao-yun;LI Hui-xin;HU Feng;LIU Man-qiang

2009, 20(02):  435-440 . 

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In a microcosm experiment, the effects of the interaction between soil fungi-feeding nematodes and microorganisms on the soil functional stability under persistent stress of CuSO4 or transient stress of heating to 40 ℃ for 18 h were studied, with the short-term decomposition of barley leaf powder as a representative of soil function. The results showed that whether the stress existed or not, inoculation of fungi-feeding nematodes could enhance soil basal respiration, an overall indicator of soil microbial activity. Under copper stress, the soil basal respiration after the inoculation increased significantly during the period from the 8th day to the end of the experiment (P<005); while under heat stress, the promotion effect of the inoculation was only significant at the 8th day of the experiment, suggesting that the influence of fungi-feeding nematodes on soil microorganisms varied with stress type. Under the two stresses, inoculation of fungi-feeding nematodes had no influence on the resistance of soil function but could promote its recovery, and the soil fungal biomass in the late period of the experiment was lower in the treatment of inoculation than in CK, indicating that under stress condition, fungi-feeding nematodes depressed the growth and development of soil fungi, and possibly, indirectly promoted bacterial development.

Effects of salicylic acid on the leaf photosynthesis and antioxidant enzyme activities of cucumber seedlings under low temperature and light intensity.

LIU Wei^1,2;AI Xi-zhen^1,2;LIANG Wen-juan^1,2;WANG Hong-tao^1,2;LIU Sheng-xue^1,2;ZHENG Nan^1,2

2009, 20(02):  441-445 . 

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In order to elucidate the regulation functions of salicylic acid (SA) o n the photosynthesis of cucumber under low temperature and light intensity, the seedlings of cucumber ‘Jinyou 3’ under low temperature and light intensity wer e foliar-sprayed with different concentration SA, and the leaf gas exchange par ameters, photochemical efficiency, MDA content, and antioxidant enzyme activitie s were measured. The results showed that under low temperature and light intensi ty, the leaf photosynthetic rate (Pn), stomatal conductance (Gs), tr anspiration rate (Tr), actual photochemical efficiency of PSⅡ(ΦP SⅡ), and maximal photochemical efficiency of PSⅡ (Fv/Fm) of the seedlings all decreased but the intercellular CO2 concentration (Ci) inc re ased, suggesting that non-stomatal limitation was the main cause of the decreas e of Pn under low temperature and light intensity stress. Low temperature and light intensity also led to the increase of leaf malondialdehyde (MDA) conte nt and superoxide dismutase (SOD) activity, the decrease of catalase (CAT) activ ity, and the decrease after an initial increase of peroxidase (POD) activity. Ho wever, foliar-spraying 05〖KG-*2〗-〖KG-*7〗25 mmol ·L-1 of SA before the stress increased the leaf Pn, Gs, T r, ΦPSⅡ, Fv/Fm, and activities of SOD, POD and CAT whi le decreased the Ci and MDA content, suggesting that SA could regulate the leaf photosynthetic functions of cucumber seedlings, and enhance the see dlings resistance against low temperature and light intensity. The optimum conce ntration of SA for the foliar-spraying was 1 mmol·L-1.

Effects of spermidine on seed germination and seedling antioxidant system of tomato under NaCl stress.

HU Xiao-hui¹;WANG Su-ping²;QU Bin¹

2009, 20(02):  446-450 . 

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A pot experiment was conducted to study the effect of exogenous sperm idine (Spd) on the seed germination and seedling antioxidant system of tomato cu ltivar ‘Baiguoqiangfeng’ under NaCl stress. The results showed that after soak ing with Spd, the tomato seed’s germination rate (Gr), germination index (Gi), and vigor index (Vi) increased by 104.90%, 142.31% and 12222% , respectively, and the mean germination time (MGT) shortened by 497%, compare d with the control. Soaking seed with Spd increased the seedling leaf’s superox ide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and soluble protein content, and decreased its superoxide anion (O2〖SX(B-*3〗-〖〗· 〖SX)〗) production rate, hydrogen peroxide (H2O2) content, malondialdehyd e (MDA) content, and electrolyte leakage of plasma membrane. The seedling growth was also promoted. It was concluded that soaking seed with Spd could promote th e seed germination and seedling growth of tomato under NaCl stress, and enhance the salt-resistance of tomato plant.

Physiological responses of different peanut (Arachis hypogaea L.) varieties to cadmium stress.

LIU Wen-long¹;WANG Kai-rong¹;WANG Ming-lun²

2009, 20(02):  451-459 . 

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To have a deep understanding on the mechanisms of cadmium (Cd) toxicit y on peanut plants is of theoretical and practical significances for the selecti on and utilization of Cd-resistant peanut germ plasm resources. With fourteen peanut varieties as test materials and taking the chlorophyll content of functio nal leaves, malondialdehyde (MDA) content and cell membrane permeability of root s and leaves, and oxidative vitality of roots at flowering stage as test physiol ogical parameters, a sand culture experiment was conducted in an artificial clim a te chamber to investigate the physiological responses of different peanut variet ies to six levels of Cd stress. The results showed that within the range of 0〖 KG-*2〗-〖KG-*7〗60 mg Cd·L-1 addition, the chlorophyll content of functional leaves and the oxida tive vitality of roots decreased significantly with increasing Cd addition, whil e the MDA content and cell membrane permeability of leaves and roots were in adv erse. The cell membrane permeability of roots and leaves was the most sensitive physiological parameter, while the chlorophyll content of functional leaves was the least sensitive one in the responses of peanut plant to Cd stress. In the li near regression equations describing the relationships between test physiologica l parameters and Cd concentrations in nutrient solution, the absolute value of s lope (b)/intercept (a) ratio, ︱b/a︱, could better describe the sen sitivity of peanut plants to Cd stress. It was known from the integrative evaluation of︱b/a︱values and the cluster analysis of sensitivity that among the fourteen peanut varieties, “Zhonghua-4”, “Xiangnong-55” and “Xiangnong-3010-w” were hi ghly sensitive to Cd stress (first grade), “Lainong-29”, “Xiangnongxiaoguo-w2-7”, “Fenghua-2”, “Lainong-13”, “Yuhua-15” and “Fenghua-3” were sensitive (second grade), “Xiangnong-312”, “Qiyangxiaozi” and “Pingdu-01” were less sensitive (third g rade), while “Huayu-20” and “Huayu-23” were insensitive (forth grade).

Research advances on interactions among bryophytes.

BU Zhao-jun^1,2;CHEN Xu^1,3;JIANG Li-hong¹;LI Hong-kai¹;ZHAO Hong-yan^1,2

2009, 20(02):  460-466 . 

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This paper summarized the present research status and advances on the intra- and inter-specific positive interaction, intra- and inter-specific comp etition, niche, and coexistence of bryophytes. Bryophytes are generally the domi nant plants in harsh environments, and there is a trade-off between their water retention and light and nutrient resource availability. Because of the lesser importance of competition in harsh environments, the positive interaction among bryophytes is common, but the intra- and inter-specific competition among bryop hytes and the competition between bryophytes and vascular plants are not rare. C ompetition hierarchy may exist among some bryophytes, but often changes with env ironments. In the process of bryophyte community formation, the random process, nature of colonization, and difference in regeneration strategy can result in th e niche overlap and coexistence of bryophytes, and the niche differentiation res ulted from competition is also one of the mechanisms for bryophytes coexistence. Bryop hytes should not be simply classified as stress tolerated-ruderal life history strategists, and competition is still one of important factors for constructing some bryophyte comm unities and vegetations co-existed by bryophytes and vascular plants.

Soil seed bank research in China： Present status, progress and challenges.

SHEN You-xin; ZHAO Chun-yan

2009, 20(02):  467-473 . 

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By searching soil seed bank (SSB) papers from http://www.cqvip.com (19 89〖KG-*2〗-〖KG-*7〗2006) and Web of Science (1985〖KG-*2〗-〖KG-*7〗2006), the information on SSB density, species richness, and research methods were summarized according to the 29 classified v egetation types in Vegetation of China. In total, the data of 238 sites with 14 vegetation types were collected. The results showed that the research methods ad opted by different researchers and the obtained data of SSB density and species richness varied greatly. In related researches, sampling work was mostly conduct ed in April and October, sampling plot number ranged from 2 to 480, plot area ra nged from 78 cm2 to 10000 cm2, with 10 cm×10 cm and 20 cm×20 cm as most common, and total sampling area ranged from 600 cm2 to 500000 cm2, with the most being 1000〖KG-*2〗-〖KG-*7〗10000 cm2. SSB density varied from 8 ind·m-2(desert) to 65355 ind·m-2 (tropical rain forest), and spe cies richness varied from 1 (secondary bare alkali-saline patch in temperate) t o 74 (tropical seasonal rain forest) per site. SSB density and species richness were higher in tropical rain forest and seasonal rain forest than in temperate c oniferous forest, and in manmade forest than in agricultural land or barren land. Grassland, desert, and meadow had sma ller species richness. In future, the SSB research should be extended both in sc ope and in deepness, with the focus on the long term research and strategy resea rch of some important ecosystems, and the research should be incorporated into v egetation regeneration and restoration studies. The related methodological resea rch should be also emphasized in the future.

Landscape pattern change and its simulation forecast in Zigui County of Three Gorges Reservoir Area.

JIANG Huan-huan;LI Ji-hong;FAN Wen-yi;BAO Chen-guang

2009, 20(02):  474-479 . 

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Based on the TM images of 1987 and 2002, the landscape pattern change of Zigui County from 1987 to 2002 was analyzed by using landscape index method; and the simulation forecast of this change in next 50 years was conducted by usi ng Markov model. The results showed that in 1987〖KG-*2〗-〖KG-*7〗2002, the lan dscape pattern of Zigui County changed dramatically. The area of sparse wood lan d increased greatly while that of upland and shrub land decreased obviously, and the distribution of the areas of different landscape types tended to balance. T he average shape index of landscape had an overall decline, which was represente d by the concentrated and connected distribution of different landscape types, s implification of landscape shape, and obvious human interference. As a whole, th e landscape diversity and fragmentation in Zigui County were improved to some ex tent. In next 50 years, the area of sparse wood land in Zigui would have a rapid increase, followed by that of forestland, while the areas of upland and shrub l and would be declining, and the other landscape types would have a less fluctuat ion in their areas. The main driving forces of the landscape pattern change in Z igui were the relocation of the County and the implementation of forestry polici es.

Effects of simulated acid rain on decomposition of soil organic carbon and crop straw.

ZHU Xue-zhu¹;HUANG Yao²;YANG Xin-zhong¹

2009, 20(02):  480-484 . 

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To evaluate the effects of acid rain on the organic carbon decomposition in different acidity soils, a 40-day incubation test was conducted with the paddy soils of pH 548, 670 and 818. The soils were amended with 0 and 15 g·kg-1 of rice straw, adjusted to the moisture content of 400 g·kg-1 air-dried soil by using simulated rain of pH 60, 45, and 30, and incubated at 20 ℃. The results showed that straw, acid rain, and soil co-affected the CO2 emission from soil system. The amendment of straw increased the soil CO2 emission rate significantly. Acid rain had no significant effects on soil organic carbon decomposition, but significantly affected the straw decomposition in soil. When treated with pH 30 acid rain, the amount of decomposed straw over 40-day incubation in acid (pH 5.48) and alkaline (pH 818) soils was 8% higher, while that in neutral soil (pH 670) was 15% lower, compared to the treatment of pH 60 rain. In the treatment of pH 30 acid rain, the decomposition rate of soil organic C in acid (pH 548) soil was 43% and 50% (P<005) higher than that in neutral (pH 670) and alkaline (pH 818) soils, while the decomposition rate of straw in neutral soil was 17% and 16% (P<005) lower than that in acid and alkaline soils, respectively.