Table of Content

20 July 2009, Volume 20 Issue 07

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Articles

Effects of temperature, moisture and forest succession on nitrogen mineralization in hillside red soils in mid-subtropical region, China.

CHEN Fu-sheng;YU Kun;GAN Lu;LIU Yi;HU Xiao-fei;GE Gang

2009, 20(07):  1529-1535 . 

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Effects of temperature, moisture and forest succession, as well as the ir interaction on nitrogen mineralization in hillside red soils in mid-subtropi cal region were investigated. The results showed that effects of temperature and succession stage on soil ammonification rate were significant with rate at 12 ℃<24 ℃<36 ℃, and rate in shrub and Masson pine forest being lower than that in evergreen broad-leaved forest (P＜005), while the impact of moisture was not significant. Moisture and succession stage significantly affected the so il nitrification rate, with that of half-saturation being higher than natural a nd saturation moisture levels, and that in Masson pine forest being higher than in shrubs (P＜005), while temperature had no significant impact. The effec ts of temperature, moisture and succession stage on soil net N-mineralization r ate were all significant, with 12 ℃<24 ℃<36 ℃, half-saturation higher than natural and saturation, and shrubs<Masson pine forest<evergreen broad-leaved forest (P＜005). Soil ammonification and net N-mineralization rates incr eased with increasing temperature, while the maximum soil nitrification rate occ urred at medium temperature. Moderate soil moisture would benefit the nitrogen m ineralization process, and forest succession could improve soil nitrogen supply and restrain excessive nitrification.

Soil active organic matter in broadleaved forest and Chinese fir plantation in subtropical region of China.

WANG Qing-kui^1，2;FAN Bing²;XU Guang-biao²

2009, 20(07):  1536-1642 . 

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A comparative study was made on the soil active organic matter in a broadleaved forest and two Chinese fir (Cunninghamia lanceolata) plantations in subtropical region of China, aimed to understand the effects of forest conversion and continuous plantation on soil organic C and nutrient status. After the conversion from broadleaved forest to Chinese fir plantation, the contents of soil total organic C, humus C, humic acid, and fulvic acid decreased by 278%〖KG-*2〗-〖KG-*7〗521%, 322%〖KG-*2〗-〖KG-*7〗528%, 364%〖KG-*2〗-〖KG-*7〗590%, and 297%〖KG-*2〗-〖KG-*7〗500%, respectively. Continuous plantation also resulted in the decrease of soil organic C and humus contents. The contents of soil total organic C, humus C, humic acid, and fulvic acid in second generation of Chinese fir plantation were 90%〖KG-*2〗-〖KG-*7〗250%, 250%〖KG-*2〗-〖KG-*7〗380%, 286%〖KG-*2〗-〖KG-*7〗392% and 231%〖KG-*2〗-〖KG-*7〗364% lower than those in the first generation of Chinese fir plantation, respectively. More obvious effects were observed on the soil active organic matter. After the conversion from broadleaved forest to Chinese fir plantation, the maximum decrement of soil microbial biomass C and N and dissolved organic C and N was 618%, 382%, 433%, and 690%; while comparing with the first generation of Chinese fir plantation, the second generation of Chinese fir plantation had the maximum decrement of soil microbial biomass C and N and dissolved organic C and N being 347%, 293%, 304%, and 184%, respectively. Soil nutrient contents also decreased due to forest conversion and continuous plantation. In comparing with broadleaved forests, Chinese fir plantations had a decrease of soil N, P, and K contents being 157%〖KG-*2〗-〖KG-*7〗312%, 115%〖KG-*2〗-〖KG-*7〗493%, and 151%〖KG-*2〗-〖KG-*7〗338%, respectively. There were close relationships between soil nutrients and soil active organic matter fractions except cold water extractable organic N.

Effects of soil factors on vegetation community structure in an abandoned subtropical paddy wetland.

PENG Yi^1,2;LI Yu-yuan¹;LI Zhong-wu²;YE Fang-yi²;PAN Chun-xiang¹;XIE Xiao-li¹

2009, 20(07):  1543-1550 . 

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Based on the investigation data from a subtropical wetland having been abandoned from paddy agriculture for one year, a redundancy analysis was conducted on the relationships between vegetation community and soil factors in the wetland. It was found that soil moisture regime, available K and P, and pH were the main factors affecting the distribution of plant species. The common plant species could be classified into three groups, i.e., Ludwigia prostrata〖KG-*2〗-〖KG-*7〗Murdannia triquetra group (G1), Hemarthria altissima〖KG-*2〗-〖KG-*7〗Rotala rotundifolia〖KG-*2〗-〖KG-*7〗Lapsana apogonoides group (G2), and Conyza canadensis〖KG-*2〗-〖KG-*7〗Polygonum hydropiper〖KG-*2〗-〖KG-*7〗Paspalum pasaloides group (G3). G1 mainly distributed on the soils with higher available K, G2 mainly distributed in periodically flooded area, while G3 mainly distributed in drainage area and was positively correlated to soil available P and pH. Species diversity and above-ground biomass had significant positive correlations with soil pH and total K, respectively, while evenness index was significantly negatively correlated with soil available N. No significant correlations were observed among other indices.

Genetic diversity of Camellia sinensis germplasm in Guangdong Province based on morphological parameters and SRAP markers.

SHEN Cheng-wen^1,2;NING Zheng-xiang¹;HUANG Jian-an²;CHEN Dong³;LI Jia-xian³

2009, 20(07):  1551-1558 . 

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By the methods of phenotypic identification and SRAP makers amplification, the g enetic diversity of twenty-five local tea cultivars in Guangdong Provi nce and five contrastive cultivars from other regions was assessed and classifie d, and the phenotypic traits of the cultivars were clustered by Pearson correlati on and Farthest neighbor methods. The coefficient of variation of the phenotypic traits was averagely 3215%. Fine-hair had the highest coefficient of variati on (4241%), while the growth period of bud leaves had the smallest one (1852 %). Based on the cluster analysis of phenotypic traits, the test 30 tea cultivars co uld be clustered into 4 groups, 17 cultivars in the first group, 10 cultivars in the second group, 2 contrastive cultivars Yunnan-dayezhong and Lingyun-baimao ch a in the third group, and 1 contrastive cultivar Hainan-dayezhong in the fourth group. After the amplification with 21 SRAP primers, a total of 127 fragments we re detected, among which, 114 fragments were polymorphic, accounting for 8867% of the total. The amplified fragments and polymorphic fragments per primer combi nation were averagely 605 and 543, respectively. At the genetic distance of 0 39 cm, the tea cultivars could be classified into three groups A, B and C, and 8 333% of the cultivars were belonged to group A. At the genetic distance of 0.3 1 cm, group A could be further classified into three sub-groups Ⅰ, Ⅱ and Ⅲ, 13 cultivars in subgroup Ⅰ, 2 cultivars in subgroupⅡ, and 10 cultivars in subgro up Ⅲ. It was not exactly the same between the clustering based on SRAP markers amplification and the performance of phenotypic traits.

Challenge to the desertification reversion in Horqin Sandy Land.

ZHAO Xue-yong¹;ZHANG Chun-min²;ZUO Xiao-an¹;HUANG Gang¹;HUANG Ying-xin¹;LUO Ya-yong¹;WANG Shao-kun¹;QÜ Hao¹

2009, 20(07):  1559-1564 . 

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Analyses of the changes in desertified land area, water resource a vailability, land use, and plant productivity in Horqin Sandy Land in recent 50 years showed that from 1950 to the late 1980s, the land desertification in Horqin Sa ndy Land had a rapid expansion, but reversed since then. The annual runoff of Xi liaohe River decreased consistently, and in 1999, the middle reach at Tongliao s ection was dried up. In recent 20 years, the water table of Xihu Lake was decrea sed by about 10 m, and dried up in 2001. The above-ground biomass of grasslands decreased from 520 g·m-2 in 1937 to 197 g·m-2 in 2005. The main c ause of these results was the change of land use pattern, i.e., the overuse of w ater resources for re-vegetation or cropland irrigation. Water resources reduct ion was the major challenge to the desertification reversion in Horqin Sandy Lan d.

Effects of soil thickness on spatiotemporal pattern of soil moisture in catchment level.

CHEN Jia;SHI Zhi-hua;LI Lu;LUO Xuan

2009, 20(07):  1565-1570 . 

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Based on the fixed-spot observation, this paper analyzed the effects of soil th icknesses on the spatiotemporal pattern of soil moisture in the Wulongchi catchm ent of Danjiangkou, China. The soil moisture content increased soon after precip itation events, followed by a decline as the soil dried down, whilst its spatial heterogeneity exhibited an opposite pattern. The profile-averaged soil moistur e content differed significantly with soil thickness. The soil with a thickness of 20 cm had lower profile-averaged moisture content whose variation trend was s imilar to that of precipitation and varied obviously among seasons; medium thick ness (20〖KG-*2〗-〖KG-*7〗40 cm) soil had medium level of profile-averaged moi sture content whose seasonal variation was moderately and affected by the charac teristics of precipitation; while the soil with a thicknesses of >40 cm had high er profile-averaged moisture content whose seasonal variation was relatively sm all. The profile distribution pattern of soil moisture was determined by the int egrated effects of precipitation, evapotranspiration, and leakage, exhibiting in creasing-type at semi-humid stage, waving-type at humid stage, and both of th e two types at arid stage. There was a significant positive correlation be tween profile-averaged soil moisture content and soil thickness, and the correl ation coefficient was 0630〖KG-*2〗-〖KG-*7〗0855. The moisture content in 0 〖KG-*2〗-〖KG-*7〗15 cm soil layer had less correlation with soil thickness, bu t the moisture content in 20〖KG-*2〗-〖KG-*7〗55 cm soil layer was significantl y correlated with soil thickness.

Effects of land use change on soil erosion intensity in small watershed of Loess Hilly Region: A quantitative evaluation with 137-Cesium tracer.

WANG Ya-feng¹;FU Bo-jie¹;CHEN Li-ding¹;LÜ Yi-he¹;LUO Chun-yan²

2009, 20(07):  1571-1576 . 

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Based on the land use change data and by using 137Cs tracer technique, this paper studied the change process of soil erosion intensity in Yangjuangou watershed in Loess Hilly Region. Since the 1980’s, the land use intensity in the watershed decreased gradually. In 1980〖KG-*2〗-〖KG-*7〗2006, the slope arable land decreased from 949 hm2 to 02 hm2, while the forest land, shrub land, orchard land, and grassland increased from 0 to 511 hm2, from 0 to 192 hm2, from 0 to 180 hm2, and from 769 hm2 to 801 hm2, respectively. The soil erosion intensity was in the order of slope arable land > shrub land > orchard land > grass land > forest land. In 1980, 1984, 1996, and 2006, the soil erosion intensity was 64089, 53624, 49039, and 36414 t·km-2·a-1, respectively, being changed from intense to moderate. Soil and water conservation and vegetation restoration were the main causes of the decrease of soil erosion intensity in the study area.

Sensitivity evaluation and key sensitive factors identification of soil erosion around Hangzhou Bay based on RUSLE.

LI Cheng¹;LI Jun-xiang^1,2,3;ZHU Fei-ge¹;CAO Lu¹;CHEN Zhu¹;WU Tong⁴;WU Ming⁵;SUN Hai-jing⁵

2009, 20(07):  1577-1585 . 

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By using GIS and RS techniques and RUSLE, the rainfall erosiv ity (R), soil erodibility (K), vegetation and management factor (C), and slope length and steepness factor (LS) around Hangzhou Bay of Zhejiang Province, China were calculated to make a comprehensive sensitivity evaluation o f soil erosion in the study area. In the meantime, the contribution of each natu ral factor, i.e., rainfall, soil texture, slope, and elevation, was analyzed, an d a new approach, overlapping and ordering method, was developed to identify the key affecting factors in the given sensitive areas. In the study area, soil ero sion was mainly at non-sensitive and low sensitive levels. The percentages of the areas with different soil erosion sensitivity varied with the strength of th e affecting factors. Soil erosion sensitivity increased with increasing rainfall and slope, and the percentage of the area with high soil erosion sensitivity wa s the largest at elevation 200〖KG-*2〗-〖KG-*7〗500 meters. The overlapping and ordering method was a practicable approach in identifying the key affecting fac tors in given sensitive areas, being helpful to understand the mechanisms causin g soil erosion.

Soil water and its karst effect in epikarst dynamic system.

DENG Yan¹;QIN Xing-ming^1,2;JIANG Zhong-cheng¹;LUO Wei-qun¹;QI Xiao-fan^1,3

2009, 20(07):  1586-1590 . 

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This paper studied the soil physical properties, soil CO2, soil water and spring water chemistry in a mature forest and a shrub in Nongla of Guangxi, China, as well as the relationships between the chemistry of soil water and spring water, aimed to understand the karst effect of the soil water in Nongla epikarst dynamic system. Significant differences were observed in the soil bulk density and non-capillary porosity under forest and shrub, which affected soil water content. The fixed CO2 in soil water had a significant negative correlation with soil CO2, and the free CO2 in soil water was 0 mg·m-3 in the forest and 533×103mg·m-3 in the shrub. In soil water and spring water, there was a negative correlation between pH and Ca2＋, Mg2+, and Cl- concentrations, and a positive correlation between K+, Na＋, and HCO3- concentrations and organic C content. After the eluviation of rain water, the ion concentrations in leached soil water increased greatly, and accordingly, its corrosion ability enhanced greatly. The karst process in forest environment was stable and intensive, while that in shrub environment was active but weak.

Application of DNDC model in estimating cropland nitrate leaching.

LI Hu;WANG Li-gang;QIU Jian-jun

2009, 20(07):  1591-1596 . 

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The leaching amount of soil water and nitrate from winter wheat field under typical planting system in Jinan City of Shandong Province was measured wi th lysimeter during the whole growth season in 2008, and the feasibility of appl ying DNDC model to estimate this leaching amount was tested by the obtained data . On the whole, DNDC model could better simulate the soil water movement in the crop field, with the accuracy being acceptable. However, there existed definite deviation in the simulation of nitrate leaching. The simulated value (18.35 kg N ·hm-2) was 3.46 kg N·hm-2 higher than the observed value (14.89 kg N·hm-2), w ith a relative error of about 20%, which suggested that some related parameters were required to be further modified. The sensitivity test of DNDC model showed that cropland nitrate leaching was easily to be affected by irrigation and ferti lization. It was proved that the model had definite applicability in the study a rea.

Effects of maize/peanut intercropping on rhizosphere soil microbes and nutrient contents.

ZHANG Jia-en;GAO Ai-xia;XU Hua-qin;LUO Ming-zhu

2009, 20(07):  1597-1602 . 

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A field experiment was conducted to study the effects of maize/peanut intercropping on the rhizosphere soil microbial community and nutrient contents. Three treatments were installed, i.e., maize/peanut intercropping, maize monoculture, and peanut monoculture. Comparing with monoculture, intercropping could significantly increase the quantity of soil bacteria in both maize and peanut root areas. The numbers of soil actinomyces and fungi had no significant differences in the root areas of intercropped and mono-cultured peanut, but were much higher in intercropped than in mono-cultured maize root area. The functional diversity and metabolic activity of soil microbial community also improved under intercropping. Maize/peanut intercropping increased the soil alkali-hydrolysable N, available P and organic matter contents and EC to some extent, especially in the root area of maize. All the results suggested that maize/peanut intercropping could obviously improve the status of soil microbes and nutrients in root areas, which in turn, would promote the growth of intercropped crops.

Homogenization of plant diversity in Shanghai residential areas.

SONG Kun;QIN Jun;GAO Kai;HU Yong-hong

2009, 20(07):  1603-1607 . 

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Residential area’s vegetation will become an important component of C hina’s urban vegetation, and the distribution pattern of its diversity will aff ect urban vegetation diversity. Based on the residential area’s vegetation inve stigation in the urban, suburban, and rural areas of Shanghai, the plant diversi ty and species composition in the residential areas along the urban-rural gradi e nt were compared in terms of ornamental plants (OP), spontaneously occurring orn amental plants (SOOP), and weeds. There was no significant difference in the spe cies richness of OP and weeds along the gradient, but the richness of SOOP was t he highest in suburban area. The species compositions of OP, SOOP, and weeds wer e similar in the residential areas along the gradient, with 40〖KG-*2〗-〖KG-*7 〗50% of all species occurring in more than one location. The main causes induci ng the homogenization of plant diversity in Shanghai residential areas were the almost identical residential building styles and greening patterns, which limite d the planting of greening plants and the construction of heterogeneous habitats .

Regional eco-economic resilience of Changzhi City.

WANG Shu-yu;YANG Xin-mei;SHI Chun-fen

2009, 20(07):  1608-1612 . 

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Based on the theory of resilience, an eco-economic resilience coefficient model was proposed, and the regional eco-economic resilience of Changzhi City in 2001〖KG-*2〗-〖KG-*7〗2006 was analyzed. In the City, the ecological footprint was increased from 86569×106 hm2 in 2001 to 198190×106 hm2 in 2006. The ecological footprint of energy was 1/2 or more of the regional ecological footprint, and its increasing rate was decreasing and lower than that of regional economic growth. The eco-economic resilience coefficient of the City decreased from 080 in 2002 to 010 in 2006. Relative to economic growth, the demand for natural resources was decreasing. To achieve the sustainable development of Changzhi City, some countermeasures including readjusting industrial structure, changing habitant consumption patterns, increasing regional ecological capacity, decreasing the increasing rate of ecological footprint, and strengthening regional eco-economic resilience were proposed.

Ecological issues and loss risk of cold-resistant rubber germplasm resource in Xishuangbanna.

CHEN Yan-ping^1,2;WU Zhao-lu¹

2009, 20(07):  1613-1616 . 

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Based on the field investigation data and related literatures, this pa per analyzed the ecological issues in the breeding and utilization of highly col d-resistant and high-yielding rubber germplasm in Xishuangbanna, and the loss risk of this germplasm. The rubber farmers in Xishuangbanna had built a cycle pa ttern of establishing rubber nursery and managing rubber plantations to develop the local rubber industry, but the unlimited utilization of this germplasm made the rubber plantations expand to the highland with an elevation of 1300 m, resul ting in the ecological issues such as the destruction of natural forests and spec ies, decline of soil fertility, regional drought, rubber diseases and insect pes ts, and human-elephant conflicts. This germplsm and its intellectual property w ere under transnational loss without any control, making even more potential eco logical and economic risks. Great attentions should be paid by the related organ izations to take effective measures to conserve this germplsm resource to reduce its potential risks.

Vertical zonation of mountain landscape: A review.

SUN Ran-hao¹;CHEN Li-ding¹;ZHANG Bai-ping²;FU Bo-jie¹

2009, 20(07):  1617-1624 . 

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Vertical gradient of mountain landscape is about 1000 times of its hor izontal gradient, and hence, only using landscape pattern index is quite difficu lt to reflect the landscape regularity along vertical gradient. Mountain altitud inal belt is a kind of classic geographic models representing the vertical diffe rentiation of landscape, being of significance in geographic and ecological rese arches. However, the discrete expression pattern and the inaccuracy of the borde rlines of mountain vertical belts limit the roles of mountain vertical belt in a ccurately describing landscape pattern in regional scale and in explaining ecolo gical processes. This paper reviewed the research progress and existing problems on mountain altitudinal belt, put forward a suggestion of using modern informat ion technology to establish a comprehensive and continuous mountain landscape in formation chart, and discussed the framework and prospect of the establishment o f the chart, which would have reference value for accurately describing mountain landscape pattern and explaining specific ecological processes, and promote the further improvement of the methodology for mountain ecological research.

Effects of spider mite and two substitute diets on the development and reproduction of Euseius nicholsi (Ehara et Lee)(Acari: Phytoseiidae).

ZHENG Xue^1,2;JIN Dao-chao^1,2

2009, 20(07):  1625-1629 . 

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Three kinds of diets, i.e., two-spotted spider mite Tetranychus urticae Koch, Camellia oleifera Abel pollen, and mould mite Tyrophagus putrescentiae (Schrank), were used to feed Euseius nicholsi (Ehara et Lee) in laboratory at 25 ℃ and 80％ RH to study the effects of these diets on the development and reproduction of E. nicholsi. The E. nicholsi could prey on T. putrescentiae egg, but could not complete its natural development due to the deficiency of the egg. Other two diets were the favorable foods for the normal growth and reproduction of E. nicholsi. The life cycle duration, longevity, oviposition duration, and average lifetime fecundity of the adult female E. nicholsi fed with C. oleifera pollen and T. urticae were 618 d, 2479 d, 1672 d and 2303, and 567 d, 2572 d 1817 d and 2538, respectively. The quantity of the experimental E. nicholsi populations fed with these two diets all showed an increasing trend, with the population tendency index being the highest (I=1428) for the population fed with C. oleifera pollen and the double population time being the shortest (t=35201 days) for the population fed with T. urticae.

Directions of ecology specialty construction and personnel training in China.

ZHANG Jia-en;LUO Shi-ming;QIN Zhong;YE Yan-qiong;ZHAO Ben-liang

2009, 20(07):  1630-1634 . 

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This paper analyzed the present status of ecology specialty constru ction and personnel training in China. It was considered that there existed some problems to be solved, e.g., the contradiction between the rapid development of new subjects in ecology and the relative weakness in personnel qualified to teach, the unbalance between the extensive and intensive, and the deep and shall ow teaching programs for the students in ecology, the conflict between the “sof t” (theoretical) ecologcal education and the “hard” (technical) ecological con struction, and the contradiction between the limited demands and the relative su rplus supply of undergraduate students in ecology. Based on these analyses, a se ries of suggestions and countermeasures for the innovation of the teaching style s and training directions in ecological specialties were put forward, including 1) to formulate a development and construction plan of ecology specialty an d to appropriately regulate the enrollment of undergraduate students, 2) to achi eve the changes in current teaching styles from classroom to field and from “so ft” theoretical teaching to “hard” technical training, 3) to develop and impl ement a variety of diversified teaching methods, such as participative, interact ive, research-based, and innovative teaching for undergraduate students, 4) to enhance the undergraduate educational quality and teaching resource bank constru ction and to achieve teaching resource sharing, and 5) to establish “T-type” personnel training system in ecology. Some employment-oriented personnel traini ng directions in ecology specialty were also presented.

Effects of climate warming on the N₂O emission from Larix gmelinii forest soils at different latitudes during soil thawing period.

FU Min-jie^1,2;WANG Chuan-kuan¹;WANG Ying¹;LIU Shi¹;DING Shuang¹

2009, 20(07):  1635-1642 . 

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During the soil thawing period in spring, large amount of N2O was emitted from the forest soils in North China, being a major source of atmospheric greenhouse gases. However, the contribution of the emitted N2O and its responses t o climatic change are unclear. In this paper, sampling plots of Larix gmelinii  f orest (including sapling, ground vegetation, and soil A and B horizons) with sim ilar stand conditions in Tahe (52°31′ N), Songling (50°43′ N), Sunwu (49°13′ N), and Dailing (47°05′ N) were displaced to the south boundary of L. gmelinii natural distribution area to simulate that the plots were under climate warming, and their N2O fluxes were measured during the soil thawing period in spring 2 007. For the four plots, the N2O fluxes all peaked at the mid- or late stage of soil thawing. The N2O flux of the plots from Dailing, Suwu, Songling, and T ahe during soil thawing period was averagely 665±93, 543±56, 443±53, and 335±37 μg ·m-2·h-1, respectively, and significantly positively correlated to the soil temperature at 5 cm depth and the soil microbial biomass carbon at 0 〖KG-*2〗-〖KG-*7〗1 0 cm depth. No significant relationship was observed between the N2O flux and soil moisture content. The soil N2O emission during soil thawing period differ ed significantly among the plots. Both the mean N2O flux and the cumulative N 2O emission decreased with increasing latitude, mainly due to the differences in soil microbial activities and soil physical properties.

Ecological adaptability of different provenance Eupatorium adenophorum Spreng.

ZHOU Meng^1,2;LIU Wen-yao^1,3;MA Wen-zhang^1,2;ZHAO Xiang-jian^1,2

2009, 20(07):  1643-1649 . 

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By using reciprocal transplant method, Eupatorium adenophorum Spreng. s eedlings of five different provenances were reciprocally transplanted into six d ifferent sites in Yunnan Province, with the survival rate, plant height, branch number, biomass, flower number per plant, and seed production measured during th e period from April 2007 to May 2008. The seedlings growth and reproductive trai ts of different provenance E. adenophorum all showed strong plasticity to environmental conditions. With increasing latitude and altitude of transplant site, plant height, branch number, biomass, flower number per plant, and seed prod uction of different provenance E. adenophorum decreased, and the differences in these growth and reproductive traits were significant among the transplant sites . However, there were no significant differences in these traits among different provenance E. adenophorum. Provenance and transplant site had no significan t in teractive effects on the above-mentioned traits except seed production. At each site, the survival rate, growth potential, and reproductive capability of local provenance E. adenophorum didn’t have any superiority, illustrating that th e su ccess in the invasion of E. adenophorum in Yunnan Province was mainly due to the phenotypic plasticity of the plant, while local adaptability only played lesser important role.

Effects of NO₂ on Cinnamomum camphora seedlings growth and photosynthesis.

CHEN Zhuo-mei^1,2;CHEN Ying-xu¹;DU Guo-jian²

2009, 20(07):  1650-1656 . 

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A 2-month fumigation experiment was conducted with opened top chambers to study the effects of different concentration (01, 05, and 40 μl·L-1) NO2 on the growth and photosynthesis of 1-year Cinnamomum camphora seedlings. Fumigation with 01 and 05 μl NO2·L-1 promoted the growth of the se edlings, while with 40 μl NO2·L-1 was in adverse. The diurnal variat ion of net photosynthetic rate (Pn) presented two-peaks, with an obvious depression in midday. 05 μl NO2·L-1 increased the Pn, the maxi mum of Pn reached 8542 μmol CO2·m-2s-1; 40 μl NO2·L-1 decreased the Pn in most period of time; while the effect of 0 .1 μl NO2·L-1 varied with time period. Fumigation with 05 and 4.0 μ l NO2·L-1 increased the maximal and minimal values of stomatal conducta nce (Gs) and intercellular CO2 concentration (Ci), while 0.1 μl N O 2·L-1 increased th e maximal and mi nimal values of Ci but decreased the maximal and minimal values of G s. At the middle and late stages of fumigation, the mean Pn of the seedlings treated with 05 μl NO2·L-1 was significantly higher than that treated with 01 and 4 μl NO2·L-1. At the early stage of fumigation, 05 and 40 μl NO2·L-1  significantly decreased the maximal PSⅡ efficiency (Fv/Fm); and at the late st age, 40 μl NO2·L-1 still decreased the Fv/Fm significantly.

Effects of vegetation cover on physical and chemical properties of bio-crust and under-layer soil in Horqin Sand Land.

ZHAO Ha-lin¹;GUO Yi-rui¹;ZHOU Rui-lian²;ZHAO Xue-yong¹

2009, 20(07):  1657-1663 . 

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To understand the effects of different vegetation cover on the bio-crust and its under-layer soil in Horqin Sand Land, the bio-crust and 0〖KG-*2〗-〖KG-*7〗5 cm soil samples in Artemisia frigida, Salix microstachya, Populus simonii, and Pinus sylvestris var. mongolica stands were collected, and their physical and chemical properties were studied. After fifteen years enclosure protection and vegetation establishment, the flowing sand dune in most natural and artificial vegetation sites was covered with bio-crusts. The coverage degree of the crust was 50%〖KG-*2〗-〖KG-*7〗80%, with a thickness of 1〖KG-*2〗-〖KG-*7〗2 cm. In S. microstachya stand, the crust thickness, hardness, and organic matter and nutrient contents were the highest, followed by in P. sylvestris var. mongolica stand, and in A. frigida and A. frigida stands. Moss crust had higher thickness, hardness, and organic matter and nutrient contents than lichen crust. Comparing with those in flowing sand land, the physical and chemical properties of under-layer soil in test stands were improved obviously, the improvement degree being higher under moss crust than under lichen crust, and higher in S. microstachya and P. sylvestris var. mongolica stands than in A. frigida and P. simonii stands. Vegetations with moderate height and rich branches and leaves were more helpful to the development of bio-crust and the improvement of under-layer soil, because they could reduce wind velocity and accumulate more dust and litters, and the development of moss crust was more favorable than lichen crust to the improvement of its under-layer soil.

An evaluation of net carbon sink effect and cost/benefits of a rice-rape rotation ecosystem under long-term fertilization from Tai Lake region of China.

LI Jie-jing¹;PAN Gen-xing¹;ZHANG Xu-hui¹;FEI Qing-hua²; LI Zhi-peng¹;ZHOU Ping¹;ZHENG Ju-feng³;QIU Duo-sheng⁴

2009, 20(07):  1664-1670 . 

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Taking a long-term fertilized rice-rape rotation system in Taihu Lake as test objective, its annual C balance and economic benefit were estimated, based on th e measurement of past years grain yield, litter C content, and field CO2 emission as well as the investigation of material and management inputs. The ca lculated annual C sink under different fertilizations ranged from 09 t C·hm -2·a-1 to 75 t C·hm-2·a-1, and the net C sink effect under combined inorganic/organic fertilization was three folds as that under che mical fertilization. The C cost of material input ranged from 037 t C·hm- 2·a-1 to 113 t C·hm-2·a-1, and that of management input ranged from 169 t C·hm-2·a-1 to 183 t C·hm-2·a-1 . The annual economic benefit ranged from 58×103 CNY·hm-2·a -1 to 165×103 CNY·hm-2·a-1, and was 21 times higher under combined fertilization than under chemical fertilization. Comparing with that u nder chemical fertilization, the marginal cost for per ton C sink under combined inorganic/organic fertilization was estimated as 2171 CNY· t-1 C, very close to the C price of 20 Euro·t-1 C in the EU. In sum, under combined inorgani c/organic fertilization, this rice paddy ecosystem could not only have higher pr oductivity, but also present greater net C sink effect and higher economic benef it, compared with under chemical fertilizer fertilization.

Effects of two controlled-release fertilizers with different proportions of N, P and K on the nutrient uptake and growth of Chrysanthemum morifolium Ramat.

ZHU Li-xiang¹;WANG Jian-hua¹;SUN Yin-shi¹;LI Yu-peng²;SUN Li-wen³;ZHANG Chun-ling⁴

2009, 20(07):  1671-1677 . 

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A pot experiment was conducted to study the effects of two controlled-release f 〖JP2〗ertilizers CRFA (4% resin-coated, N∶〖KG-*2〗P2O5∶〖KG-*2〗K2O=14∶〖KG-*2〗14∶〖KG-*2〗14) and CRFB (4% resin-coated, N∶〖KG-*2〗P2O5∶〖KG-*2〗K2O=20∶〖KG-*2〗8∶〖KG-*2〗10) on the nutrient uptake and growth of Chrysanthemum morifolium, with common 〖JP〗compound fertilizer CCF (N∶〖KG-*2〗P2O5∶〖KG-*2〗K2O=15∶〖KG-*2〗15∶〖KG-*2〗15) as the control. Six treatments were installed, i.e., CCF1 (CCF, 6 g N·pot-1), CCF2 (CCF, 3 g N·pot-1), CRFA1 (CRFA, 6 g·pot-1), CRFA2 (CRFA, 3 g·pot-1), CRFB1 (CRFB, 6 g·pot-1), and CRFB (CRFB, 3 g·pot-1). On the 30th day of applying common compound fertilizer CCF1 and CCF2, soil available N, P and K contents were 16329 and 14526 mg·kg-1, 18039 and 16313 mg·kg-1, and 30008 and 21315 mg·kg-1, respectively, and decreased rapidly since then. In treatments CRFA1, CRFB1, CRFA2, and CRFB, soil available N content increased slowly, and reached the peak on the 60th day after fertilizing, being 12951, 13865, 11836, and 12631 mg·kg-1, respectively. Soil available P con tent had the same variation trend. Its maximum concentration was 16954 and 133 46 mg·kg-1 in treatments CRFA1 and CRFA2 on the 30th day after fertiliz ing, and 13713 and 8468 mg·kg-1 in treatments CRFB1 and CRFB2 on the 60th day after fertilizing, and decreased slowly then. The agronomic traits such as leaf area, leaf area index, branch number, flowering rate, flower number, an d flower diameter, etc., in treatments CRFA and CRFB were obviously better than those of the control, and CRFB was better than CRFA, suggesting that CRFB more m atched the nutrient demand of C. morifolium. Under the conditions of present experiment, applying CRFB2 obtained the highest yield.

Effects of different water and fertilizer supply on cucumber soil nutrient content, enzyme activity, and microbial diversity.

WEI Ze-xiu¹;LIANG Yin-li^1,2;INOUE Mitsuhiro³; ZHOU Mao-juan¹;HUANG Mao-lin¹;GU Jian-feng¹;WU Yan¹

2009, 20(07):  1678-1684 . 

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With cucumber (Cucumis sativus L.) variety Jinyou 1 as test material, a greenhouse experiment was conducted to study the effects of different water an d fertilizer supply on the cucumber soil nutrient content, enzyme activity, and microbial diversity. Three water regimes (50%〖KG-*2〗-〖KG-*7〗60%, 70%〖KG-*2 〗-〖KG-*7〗80%, and 90%〖KG-*2〗-〖KG-*7〗100% soil relative moisture content) and two fertilization practices (600 kg N·hm-2 + 420 kg P2O5·hm-2 and 420 kg N·hm-2+294 kg P2O5·hm-2) wer e designed. The increase of water and fertilizer supply benefited the increase o f soil available P content and sucrase activity. Increasing fertilization rate i ncreased soil NH4+-N content but decreased soil protease activity, and incr easing soil relative moisture content decreased the soil NH4+-N content and urease activity. Soil microbial diversity had no significant correlations with soil nutrient contents, but significantly positively correlated with soil urease activity and negatively correlated with soil sucrase activity. Among the treatm ents, the treatment 70%〖KG-*2〗-〖KG-*7〗80% soil relative moisture content + 6 00 kg N·hm-2 and 420 kg P2O5·hm-2 had the highest soil nutrien t contents, soil urease, sucrase, and phosphatase activities, and soil microbial diversity and evenness, being the best in soil potential productivity.

Quantitative relationships between hyper-spectral vegetation indices and leaf area index of rice.

TIAN Yong-chao;YANG Jie;YAO Xia;ZHU Yan;CAO Wei-xing

2009, 20(07):  1685-1690 . 

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Based on field experiments with different rice varieties under differ ent nitrogen application levels, the quantitative relationships of rice leaf are a index (LAI) with canopy hyper-spectral parameters at different growth stages were analyzed. Rice LAI had good relationships with several hyper-spectral vege tation indices, the correlation coefficient being the highest with DI (differenc e index), followed by with RI (ratio index), and NI (normalized index), based on the spectral reflectance or the first derivative spectra. The two best spectral indices for estimating LAI were the difference index DI(854,760) (based on two spectral bands of 850 nm and 760 nm) and the difference index DI (D676,D 778) (based on two first derivative bands of 676 nm and 778 nm). In general, the hyper-spectral vegetation indices based on spectral reflectance performed better than the spectral indices based on the first derivative spectra. The test s with independent dataset suggested that the rice LAI monitoring models with di fference index DI (854,760) as the variable could give an accurate LAI estimatio n, being available for estimation of rice LAI.

Salt resistance of different tomato genotypes at seed germination stage.

YANG Feng-jun^1,2;LI Tian-lai¹;ZANG Zhong-jing³;SHU Yue¹;LU Shao-wei¹

2009, 20(07):  1691-1697 . 

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Based on the cluster analysis of relative germination potential and relative germination rate under NaCl stress, fourteen tomato genotypes were clustered into two groups. Five tomato genotypes held high resistance to NaCl stress, and nine tomato genotypes were moderately NaCl- tolerant. The highly NaCl-tolerant genotypes wild Lycopersicon pimpinellifolium, Liaoyuanhongmanao and Hongbaoshi and the moderately NaCl- tolerant genotype Liaoyuanhongduoli were then under different Na+-salts and NaCl, Na+, and Cl- stresses. The responses of the four tomato genotypes to different Na+-salts stress were the same as those to NaCl stress. Among the test Na+-salts, NaHCO3 had the greatest impact. Under the stress of 100 mmol NaHCO3·L-1, the embryo’s relative lengths of the four tomato genotypes were all below 8 %. The inhibitory effect of test Na+-salts on tomato seed germination was in the order of NaNO3<Na2SO4<NaH2PO4<NaCl<NaHCO3. As for NaCl, Na+ and Cl-, the Cl- had the smallest injury.

Physiological characteristics of rice seedlings roots under aluminum stress.

XIE Guo-sheng¹;SHI Rui-hong^1，2;PANG Zhen-wu¹;CAI Ke-tong¹

2009, 20(07):  1698-1704 . 

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A hydroponic experiment was conducted with the four-leaf stage seedlings of aluminum (Al)-susceptible rice variety IR24 and Al-tolerant rice varieties Jingyou 725 and Liangyoupeijiu to study the physiological characteristics of the seedlings roots under effects of 0, 05 mmol·L-1, and 75 mmol·L-1 of Al. Under the stress of 75 mmol Al·L-1, Al-tolerant varieties had a far lesser decrement of root vigor than Al-susceptible variety, while the Al-susceptible variety had a higher root mitochondria H2O2 content than Al-tolerant varieties. Al stress induced a lesser increment of CAT activity in the root mitochondria of all tested varieties. With the increasing Al concentration, the root mitochondria POD activity of IR24 and Jingyou 725 decreased after an initial increase while that of Liangyoupeijiu was increasing, and the root mitochondria APX activity of IR24 decreased after an initial increase while that of Jingyou 725 and Liangyoupeijiu was increasing. The root glutamic acid content of all tested varieties showed an increase-decline trend, and their citric acid content decreased while PEP content increased. The ratio of cyanide-resistant respiration rate to total respiration rate of Al-tolerant Jingyou 725 and Liangyoupeijiu increased obviously, compared with that of Al-susceptible IR24.

Effects of calcium on cadmium bioavailability in lateritic red soil and related mechanisms.

SONG Zheng-guo^1,2;XU Ming-gang²;LI Ju-mei²;JU Xue-hai¹;TANG Shi-rong¹

2009, 20(07):  1705-1710 . 

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A pot experiment with Cd-polluted lateritic red soils was conducted to study the effects of applying different concentration (0, 40, 100, and 200 mg·kg-1) Ca on the rape biomass, its Cd uptake, and the Ca and Cd concentrations in soil solution. Comparing with no Ca application, applying Ca increased the rape dry mass, whether under high or low level Cd pollution. The increment of the dry mass in two cropping seasons was averagely 55% (low level Cd pollution) and 173% (high level Cd pollution). The Ca concentration both in soil solution and in rape plant increased markedly with increasing Ca application rate. At the Ca application rate 100 mg·kg-1, the Cd concentration in soil solution increased by 745% (low Cd pollution) and 310% (high level Cd pollution), while that in rape plant decreased by 45% (low Cd pollution) and 131% (high level Cd pollution). There was a positive relationship between the Ca/Cd (mass ratio) in soil solution and the Cd concentration in rape plant under both low and high levels Cd pollution. The Ca/Cd (mass ratio) in soil solution affected the bioavailability of soil Cd, and further, affected the Cd uptake by rape.

Ecological responses of Brassica juncea-alfalfa intercropping to cadmium stress.

LI Xin-bo;XIE Jian-zhi;LI Bo-wen;WANG Wei

2009, 20(07):  1711-1715 . 

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A pot experiment was conducted to study the effects of cadmium (Cd) stress on the soil-plant system under Brassica juncea-alfalfa intercropping, and to evaluate the Cd feed safety of alfalfa. Comparing with monoculture, when the soil Cd content was in the range of 037〖KG-*2〗-〖KG-*7〗2037 mg·kg-1, intercropping decreased the B. juncea biomass by 04%〖KG-*2〗-〖KG-*7〗118% while increased the alfalfa biomass by 553%〖KG-*2〗-〖KG-*7〗700%. Soil available Cd was mainly determined by soil total Cd and plant species, and less affected by planting pattern. Comparing with monoculture, when the soil Cd content was in the range of 037〖KG-*2〗-〖KG-*7〗537 mg·kg-1, intercropping increased the Cd content in above-ground part of B. juncea by 145%, but decreased the Cd content in above-ground part of alfalfa by 571%. The Cd contents in the above-ground parts of alfalfa under monoculture and intercropping were 021 and 009 mg·kg-1, respectively, neither of them being over the feed safety standard (05 mg·kg-1). When the soil Cd content was in the range of 1037〖KG-*2〗-〖KG-*7〗2037 mg·kg-1, though the Cd contents of mono-cultured and intercropped alfalfa were both over the standard, the Cd contents in the above-ground parts of alfalfa and B. juncea under intercropping were decreased by 28%〖KG-*2〗-〖KG-*7〗483% and 11%〖KG-*2〗-〖KG-*7〗486%, respectively. Under both monoculture and intercropping, the Cd transport coefficient of B. juncea was far greater than that of alfalfa.

Forage habitat selection of white-naped crane during its incubation period in Zhalong Wetland.

WU Qing-ming;ZOU Hong-fei

2009, 20(07):  1716-1722 . 

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By using the methods of fixed-spot observation, GPS positioning, sampling plot investigation, and factor analysis, the forage habitat selection of white-naped crane (Grus vipio) during its incubation period in Zhalong Wetland was studied f rom April to May 2002〖KG-*2〗-〖KG-*7〗2008. In the study area, the crane durin g its incubation period chose a variety of habitat types as its forage habitat, among which, wetland (reed swamp) was the main one, occupying 7436% of the tot al, followed by farmland. The forage habitat included four elements, i.e., habit at identification, food, water, and cover, and the main selection criteria were the identification factor and energy factor, followed by eating feasibility fact or, security distance factor, and concealment factor. The forage habitat selecti on of the crane during its incubation period had two levels (macro- and microha bitat) and three courses (forage habitat type choice, forage area choice, and fo rage microhabitat choice).

Habitat characteristics of Andrias davidianus in Zhangjiajie of China.

LUO Qing-hua

2009, 20(07):  1723-1730 . 

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By the methods of field investigation and laboratory analysis, the hab itat characteristics of Chinese giant salamander （Andrias davidianus） in Zhangjiaj ie Giant Saramander National Nature Reserve were studied from July to August in 2006〖KG-*2〗- 〖KG-*7〗2008. In the study area, the inhabited reaches of A. davidianus were ch aracterized by moderate altitude (373±97 m), relatively small river width (63 9±213 m) and depth (107±053 m), lithoid substrate with more gravels or r ocks, irregular river bed, stony river bank with more scrub vegetation and larger cov erage (>50%), steeper bank gradient (58°±17°), higher water flow rate (033±0 08 m·s-1), and weaker anthropogenic disturbances. There were many burro ws (4±2 ind·100 m-1) in the habitat, and the water flow rate in the bur rows were relatively low (022±010 m·s-1). The waters in the habitat were with high DO (723±085 mg·L-1), low COD (400±251 mg·L- 1), low TN (011±015 mg·L-1), moderate total hardness (13716±67 69 mg·L-1), and lesser coliform groups (3419±3407 ind·L-1) . Crabs were the most important food organisms affecting the A. davidianus population in the study area, followed by shrimps.

Impacts of large hydropower station on benthic algal communities.

JIA Xing-huan^1,2;JIANG Wan-xiang^1,3;LI Feng-qing¹;TANG Tao¹;DUAN Shu-gui¹;CAI Qing-hua¹

2009, 20(07):  1731-1738 . 

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To investigate the impacts of large hydropower station in Gufu River on benthic algae, monthly samplings were conducted from September 2004 to June 2007 at the site GF04 which was impacted by the hydropower station, with the site GL03 in Gaolan River as reference. During sampling period, no significant differences were observed in the main physicochemical variables between GF04 and GL03, but the hydrodynamics differed significantly. GL03 was basically at a status of slow flow; while GF04, owing to the discharging from the reservoir, was at a riffle status during more than 60% of the sampling period. Such a difference in hydrodynamics induced significant differences in the community similarity of benthic algae and the relative abundance of unattached diatoms, erect diatoms, and stalked diatoms between GF04 and GL03, which could better reflect the impacts of irregular draw-off by large hydropower station on river eco-system.

Management effectiveness of China nature reserves: Status quo assessment and countermeasures.

QUAN Jia;OUYANG Zhi-yun;XU Wei-hua;MIAO Hong

2009, 20(07):  1739-1746 . 

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Based on the questionnaire of World Bank/World Wide Fund for Nature (WB/WWF) management effectiveness tracking tool, a survey was conducted in 535 China nature reserves to assess their management effectiveness, with the countermeasures suggested. The 535 nature reserves had an average score of 5195, and 6935% of them had a score less than 60, illustrating that the general management level of our nature reserves was relatively low. There was a significant difference (P<001) in the scores of management effectiveness among the nature reserves of different class and established at different time, i.e., the higher class and the longer establishing time, the higher score of management effectiveness. However, no significant differences (P>005) were observed in the scores among the reserves with different area and type. The average scores of management base, management mechanism, management behavior, and management effectiveness were 155, 144, 152, and 190, respectively. The indices (management of protection targets, condition assessment, reserve boundary, resource management, and management agency) had the highest average scores, while equipment use and maintenance, community co-management, budget sources, budget expending and management, and management system and regulations had the lowest ones. The management system for China nature reserves had been generally established, the major targets and their values had been successfully protected, but there were still many problems in the management of China nature reserves, such as management mechanism and management base construction. To improve the management effectiveness, some countermeasures should be taken, e.g., establishing rational distribution and management mechanisms of budgets, strengthening ability construction, and promoting community participation.

Assessment of land use environmental impacts in urban built-up area: A case study in main built-up area of Nanchang City.

CHEN Wen-bo¹;LIU Shi-yu¹;YU Dun¹;ZOU Qiu-ming²

2009, 20(07):  1747-1752 . 

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Based on the relevant studies of land use environmental impacts and the characteristics of urban land use, a conceptual model on the assessment of land use environmental impacts in urban built-up area was established. This model grouped the land use environmental impacts in built-up area into four basic processes, i.e., detailization, abstractization, matching, and evaluation. A case study was conducted in the main built-up area of Nanchang City, with noise, smell, dust, and hazard as the impact factors. In the test area, noise had a widespread impact, its impacting area accounting for 59% of the total, smell and dust impacts centralized in the east and south parts, while hazard impact was centralized in the southeast part, an industrial area. This assessment model of four basic processes was practical, and could provide basis for the decision-making of urban land use management and planning.

Dynamic analysis of ecological footprint of Dongying City based on a modified model.

YANG Hai-bo^1,2;WANG Zong-min^1,2;ZHAO Hong-ling¹;LI Ji-ren³

2009, 20(07):  1753-1758 . 

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Taking the spatiotemporal heterogeneity of water-heat condition into consideration, the traditional ecological footprint (EF) model was modified with net primary productivity (NPP). In the meanwhile, water resource EF was calcula ted to complement the deficiency of water EF account which only included water’ s fishing function. The EF dynamics of Dongying City from 1996 to 2003 was analy zed by using the modified model. Based on traditional model, the EF of Dongying City in 1996〖KG-*2〗-〖KG-*7〗2003 increased from 1766 hm2 to 2644 hm2, and the ecological capacity (EC) decreased from 0889 hm2 to 0813 hm2; w hile based on the modified model, the EF increased from 2819 hm2 to 3776 h m2, and the EC decreased from 1935 hm2 to 1865 hm2. Comparing with tha t from traditional model, the ecological pressure calculated by the modified mod el was lesser, which suggested that to increase the utilization of water resourc e would alleviate the ecological pressure on the region. The modified EF model w as more precise to reflect the natural resource utilization of Dongying City.

Spatiotemporal changes of wetlands in Hangzhou Bay Industrial Belt.

LU Zhang-wei¹;WU Ci-fang¹;YUE Wen-ze¹;LIU Yong²;REN Li-yan¹

2009, 20(07):  1759-1764 . 

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By using RS and GIS techniques, the spatiotemporal changes of wetlands in Hangzhou Bay Industrial Belt, one of the most developed zones in Zhejiang Pr ovince, from 1990 to 2005 were studied. There was a frequent conversion between the wetlands and other land use types and between the wetlands themselves, mainl y manifested in the conversion between wetland and farmland, and from wetland to construction land and from tidal flat to aquiculture area. The comparative adva ntage of other land use types and the policy of cultivated land’s requisition- compensation balance decided the inherent mechanisms of these spatiotemporal cha nges. Driven by the aquaculture’s comparative advantage to traditional agricult ure, large areas of inland farmland and of the tidal flat along the coast of Han gzhou Bay were reclaimed into aquiculture area, and the rapid expansion of const ruction land, limited land resources, and the implement of cultivated land’s re quisition-compensation balance policy induced the wetlands being occupied.

Effects of introducing Eucalyptus on indigenous biodiversity.

PING Liang^1,2;XIE Zong-qiang¹

2009, 20(07):  1765-1774 . 

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Eucalyptus is well-known as an effective reforestation tree species, due to its fast growth and high adaptability to various environments. Howev er, the introduction of Eucalyptus could have negative effects on the local envi ronment, e.g., inducing soil degradation, decline of groundwater level, and decr ease of biodiversity, and especially, there still have controversies on the effe cts of introduced Eucalyptus on the understory biodiversity of indigenous pl ant communities and related mechanisms. Based on a detailed analysis of the literatu res at home and abroad, it was considered that the indigenous plant species in t he majority of introduced Eucalyptus plantations were lesser than those in n atural forests and indigenous species plantations but more than those in other exoti c species plantations, mainly due to the unique eco-physiological characteristi cs of Eucalyptus and the irrational plantation design and harvesting techniq ues, among which, anthropogenic factors played leading roles. Be that as it may, the negative effects of introducing Eucalyptus on local plant biodiversity coul d be minimized via more rigorous scientific plantation design and management based o n local plant community characteristics. To mitigate the negative effects of Eucalyptus introduction, the native trees and understory vegetation in plantations should be kept intact during reforestation with Eucalyptus to favor the normal d evelopment of plant community and regeneration. At the same time, human disturba nce should be minimized to facilitate the natural regeneration of native species.

Soil phosphorus form and fractionation scheme: A review.

ZHANG Lin¹;WU Ning¹;WU Yan¹;LUO Peng¹;LIU Lin¹;CHEN Wen-nian¹;HU Hong-yu²

2009, 20(07):  1775-1782 . 

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As an essential element of plant nutrition, phosphorus plays an import ant role in the agricultural sustainable development and ecosystem balance. Adop ting appropriate soil phosphorus fractionation scheme to study the forms, transf ormation, and availability of soil phosphorous is critical for understanding soi l phosphorus supply and its losses. This paper reviewed the recent researches about the forms of soil inorganic and organic phosphorous, as w ell as their fractionation schemes and limitations. Hedley method, a widely used soil phosphorous fractionation scheme, gives attention to both organic and inor ganic phosphorous forms, being available to understand the bioavailability and d ynamics of soil phosphorus. The process of Hedley method and its application sco pe were described. A detailed discussion of its modification, the Tiessen method , was also presented.