Table of Content

08 August 2011, Volume 30 Issue 08

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Articles

Density dependence-determined plant biomass allocation pattern.

2011, 30(08):  1579-1589. 

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A simulation experiment under natural condition was conducted to study the dynamics of biomass accumulation, biomass allocation percentage, biomass ratio, and morphological traits of Allium cepa var. proliferum at different plant densities (36, 49, 64, 121 allocatione to and 225 individuals·m^-2), aimed to analyze the effects of density-dependence on the biomass allocation pattern of A. cepa var. proliferum. With increasing plant density, the biomass allocation to above-ground part, leaf, and sheath increased, but less to  below-ground part and bulb, while the blomass allocation to root biomass remained constant. The biomass ratios of above- to below-ground parts, sheath to leaf, root to sheath, bulb to root, bulb to leaf, bulb to sheath, and bulb to shoot exhibited apparent density-dependence, but the ratios of root to leaf and root to shoot remained unchanged. With the growth of plant, the ratios of sheath to leaf and bulb to root increased gradually, ratios of root to sheath, root to leaf, and root to shoot were in reverse, ratios of bulb to leaf, bulb to sheath, and bulb to shoot increased after an initial decrease, and the ratio of above- to below-ground parts decreased after an initial increase. Plant density had significant negative effects on specific leaf area (P<0.001), positive effects on leaf area and root length (P<0.05), but less effects on specific root length (P>0.05). All the results suggested that intraspecific competition exerted great influence on the resource allocation inside plant bodies. In response to different plant densities, the biomass allocation patterns displayed plasticity. With the increase of plant density, the photosynthates allocated more to above-ground vegetative organs, with the cost of decreasing the photosynthates allocation to below-ground asexsual reproductive organ. It was appeared that the “optimal partitioning theory” was only applicable at the absence of plant competition between individual plants. When the competition between plants was present, the population density and density-dependent regulation were the important factors determining plant biomass allocation pattern.

Allelopathic potential and resource competition capability of Amaranthus retroflexus under different nitrogen supply.

2011, 30(08):  1590-1597. 

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In order to approach the relationships between the allelopathy and the resource competition capability of Amaranthus retroflexus during its invasion to farmland ecosystem, a sand culture experiment with A. retroflexus and Glycine max was conducted to study the biomass accumulation and allocation and the nitrogen content in different organs of the two plants under four levels of nitrogen supply with or without the addition of activated carbon. Under lower nitrogen supply, the allelopathic potential of A. retroflexus increased, and its biomass was mainly allocated to reproduction organs, under higher nitrogen supply, the allelopathic potential of A. retroflexus  decreased, and its biomass was mainly allocated to root and leaf. Under the conditions of poorer nitrogen nutrition, the nitrogen content of G. max was significantly lower when active carbon was added, compared with the control, but the difference became smaller when the nitrogen supply was increasing. These results suggested that the A. retroflexus during its invasion could adjust its allelopathic potential and biomass allocation to adapt different levels of nitrogen nutrition.

Effects of different proportion mixed Phyllostachys pubescens leaf litter on litter decomposition in P. pubescens forest.

2011, 30(08):  1598-1603. 

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Mixed Phyllostachys pubescens forest has high productivity and good ecological functions, which is possibly related to the nutrient return characteristics of mixed litter. By using litterbag method, a one-year experiment was conducted to study the decomposition characteristics of different proportion mixed P. pubescens leaf litters in P. pubescens forest in the Yangkou National Forest Farm, Fujian Province of Southeast China. Five treatments were installed, i.e., pure P. pubescens leaf litters (Ⅰ), P. pubescens+Phoebe bournei litters (mass ratio 8:2, Ⅱ), P. pubescens+Cunninghamia lanceolata litters (8:2, Ⅲ), P. pubescens+P. bournei litters (5:5, Ⅳ), and P. pubescens+C. lanceolata litters (5:5, Ⅴ). The litter decomposition rates of different treatments were all compatible with the exponential decomposition model of Olson (R²>0.92, P<0.01). The decomposition rate in treatmentsⅠand Ⅱwas significantly higher than that in other treatments, and the coefficient of decomposition was in the order of Ⅱ >Ⅰ > Ⅲ > Ⅴ > Ⅳ, being 0.68, 0.66, 0.58, 0.55, and 0.49, respectively, which illustrated that only appropriate proportions of mixed tree species leaf litters could promote the litter decomposition. The litter of mixed bamboo-broadleaved forest had higher decomposition rate than that of mixed bamboo-conifer forest. Therefore, the mixed bamboo-broadleaved forest could benefit the persistent productivity of bamboo forest. During decomposition, the N, P, and K in the litters had different release patterns. The N followed the pattern of alternate enrichment and release; the P was rapidly enriched in the first four month, released from the fourth month to fifth month, and then enriched; the K was released in the first three months, and then enriched. The nutrient return of the litters was closely related to the nutrient contents of the litters. The litter C/N ratio and P content could be the key indices for the litter decomposition.

Environment-dependence of seed germination in autumn in Grurbantonggut Desert.

2011, 30(08):  1604-1611. 

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Seed germination time scatters in different seasons, being propitious to the resources utilization and the population continuation and growth. In this paper, a field survey was conducted on the autumn-germinating plant species and their distribution in Grurbantonggut Desert, and, based on the biological characteristics of their seeds and the responses of the seeds germination to air temperature and soil moisture, the common characteristics of the seeds and the environment-dependence of their germination were studied. Among the 67 sites surveyed, 33 sites had autumn-germinating species, and most of them were ephemeral plants. The fruits of autumn-germinating plants were easy to dehiscence, and the seeds had a shorter life span without dormancy. The seed germination had a broader high temperature threshold, and the germination type was not a low-temperature type of early spring but in correspondence to the temperature in autumn (September-November). The germination was sensitive to soil moisture. Redundancy analysis further revealed that soil moisture was a limiting factor to the germination time of the seeds, and affected the distribution of autumn-germinating plants. Because of the increasing precipitation in autumn and winter and the shortening frozen period in winter under the background of climate change, it was deduced that that the species and number of autumn-germinating plants in Gurbantunggut Desert would be increased.

Difference of rainfall use strategy between Haloxylon ammodendron and Haloxylon persicum in Gurbantonggut Desert.

2011, 30(08):  1612-1619. 

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By the method of simulated rainfall, this paper studied the redistribution of rainfall on shrubs Haloxylon ammodendron and H. persicum in Gurbantonggut Desert, and investigated the root distribution of the shrubs in 0-100 cm soil layer. Regression analysis showed that the stemflow, throughfall, and interception of the shrubs had logarithmic correlation with rainfall. The rainfall redistribution on the two shrubs had no significant difference at the same rainfall intensities, but differed significantly at different rainfall intensities. The stemflow of H. ammodendron and H. persicum at rainfall intensity 20 mm·h^-1 was 2.3 and 2.9 times of that at 30 mm·h^-1, respectively. The root system of H. persicum was mainly distributed in surface soil, and 86% of the lateral roots were distributed in 0-60 cm soil layer. The amount of the lateral roots of H. persicum  in 0-20 cm, 20-40 cm, and 40-60 cm soil layers was 10.0, 9.6, and 10.9 times of that of H. ammoderdron, respectively. The extending space of H. persicum lateral roots was significantly larger than that of H. ammoderdron’s, and the root coronal radius of H. persicum was larger than that of H. ammoderdron, being 7.1 m and 2.3 m, respectively. All the results suggested that in the study area, H. persicum  could use rainwater more efficiently than H. ammoderdron via the synergistic effects of the special plant morphological structure to increase the redistribution of throughfall and the root absorption of water. H. persicum had sparse distribution of lateral roots, and thereby, this shrub had limited capability of using rainfall and more tended to use underground water.

Effects of exogenous nitric oxide on biomass and chlorophyll fluorescence of Catharanthus roseus seedlings under NaCl stress.

2011, 30(08):  1620-1626. 

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A pot experiment in greenhouse was carried out to study the effects of different concentration exogenous NO donor (sodium nitroprusside, SNP) on the biomass, chlorophyll content, and chlorophyll fluorescence of Catharanthus roseus seedlings under the stress of 50 mmol NaCl·L^-1. Among the treatments with SNP, the seedlings treated with 50 mmol NaCl·L^-1 + 0.1 mmol SNP·L^-1 had the highest  fresh weight and dry weight, being significantly higher (18.8% and 13.9%, respectively) than the control (50 mmol NaCl·L^-1). Similar to biomass, the chlorophyll a, chlorophyll b, and carotenoid contents in treatment 50 mmol NaCl·L^-1 + 0.1 mmol SNP·L^-1 were the highest, but had no significant differences with the control. The variation trend of chlorophyll a/b was more complicated. Applying 0.1 mmol·L^-1 of SNP had the best effect in mitigating the salt damage to PSⅡreaction center, which increased the fluorescence (F_v), maximal fluorescence (F_m), light energy transformation efficiency of PSⅡ (F_v/F_m), activity potential of PSⅡ (F_v/F_o), actual photochemical efficiency of PSⅡ (φ_PSⅡ), and photochemical quenching (q_P) markedly, and decreased the minimal fluorescence (F_o) and non-photochemical quenching (q_N) obviously. To sum up, 0.1 mmol·L^-1 of SNP had the best effect in protecting chlorophyll and PSⅡ reaction center against salt damage, and also, could promote the growth of the seedlings and enhance their tolerance to 50 mmol·L^-1 NaCl stress.

Responses of two turfgrass species seed germination and seedling growth to phenanthrene stress.

2011, 30(08):  1627-1631. 

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An exposure experiment of seeds in Petri dishes was conducted to study the responses of Lolium perenne and Trifolium repens seed germination and seedling growth to different concentration phenanthrene and different soil ameliorants. No significant differences were observed in the germination percentage and seedling growth among the two plants under different concentration phenanthrene, but the indices became worsened with increasing phenanthrene concentration. Several approaches for ameliorating contaminated soil had definite positive effects on the seed germination and seedling growth of the two grasses, among which, the combined application of surfactants and tree litters had better effects than their single treatments.

Effects of manganese stress on Phytolacca americana growth and development.

2011, 30(08):  1632-1636. 

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A hydroponic experiment was conducted to study the growth responses of Phytolacca americana to the stress of different Mn concentrations (1, 5, 8, 12, and 15 mmol·L^-1). With the increasing Mn concentration in growth medium, the seed germination rate, germination potential, and mitotic index of P. americana decreased, root growth was inhibited gradually, root activity presented a decreasing trend, and the biomass of plant organs reduced. Under the stress of Mn≥ 12 mmol·L^-1, the Mn had very obvious toxic effect on the growth of P. americana, which was manifested in the serious inhibition of seed germination, root tip’s cell division, and seedling’s root growth and in the significant decrease of plant biomass. Mn stress had little effects on the buds of P. americana seedlings, but large effects on the reproductive organ, resulting in a great decrease of bearing fruit quantity and quality.

Effects of elevated atmospheric O₃ on N, P, and K concentrations in soil and wheat plant during wheat growth season.

2011, 30(08):  1637-1641. 

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Taking the rice/wheat ozone free-air concentration enrichment (O₃-FACE) system in Jiangdu County of Jiangsu Province as a platform, this paper studied the effects of elevated atmospheric O₃ (target at 50% above ambient) on the N, P, and K concentrations in soil and wheat plant during wheat growth season. In the whole growth season of wheat, the concentrations of soil NH₄⁺-N,NO₃^--N, and available K under elevated O₃ decreased by 5.7%, 3.6% and 3.0%, respectively, while the soil available P concentration increased by 26.3% (P<0.05), compared with those under ambient O₃. Under elevated O₃, the K concentration in wheat plant at jointing stage increased by 28.4% (P<0.01), the plant N concentration at maturing stage decreased, while the P and K concentrations in wheat grain increased by 6.5% and 4.2%, respectively. Our results suggested that elevated atmospheric O₃ could promote the N and K uptake by wheat plant in its whole growth period, increase the K and P concentrations in wheat grain, but decrease the N concentration in wheat plant at maturing stage.

Effects of water addition and fertilization on soil nutrient contents and pH value of typical grassland in Inner Mongolia.

2011, 30(08):  1642-1646. 

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With the combination of field experiment and laboratory analysis, this paper studied the effects of water addition and nitrogen (N) and phosphorus (P) fertilization on the soil properties of typical grassland in Inner Mongolia. Water addition and fertilization showed less effect on the soil organic C and total N contents. Water addition decreased the soil NH₄⁺-N and NO₃^--N contents by 31.1% (P<0.01) and 7.9% (P<0.001), respectively, and N fertilization increased the soil NH₄⁺-N and NO₃^--N contents significantly (P<0.01). Under P fertilization, soil total P and available P contents were 1.7 and 5.9 times of the control, respectively (P<0.01). Soil pH increased significantly with water addition (P<0.01), but decreased in different degree under N and P fertilization. All the results suggested the obvious effect of water addition and N and P fertilization in improving the soil properties in temperate grassland in Inner Mongolia, which would be of importance for the restoration and management of degraded grassland in North China.

Effects of controlled-release compound fertilizer on flue-cured tobacco leaf physiological properties and nitrogen, phosphorus, and potassium contents.

2011, 30(08):  1647-1653. 

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A pot experiment was conducted to study the effects of applying controlled-release compound fertilizer on the flue-cured tobacco leaf physiological properties and nitrogen, phosphorus and potassium contents. Increasing the application rate of controlled-release compound fertilizer largely improved the tobacco leaf chlorophyll content in whole growth period, the carotenoids content and superoxide dismutase activity at spherical plant-topping stag, and the asorbic
acid content and peroxidase activity at fast growing-mature stage. In the meantime, the leaf nitrogen, phosphorus and potassium contents also showed an increasing trend. On the contrary, increasing the application rate of controlled-release compound fertilizer markedly decreased the leaf carotenoids content at mature stage, the malondialdehyde and ascorbic acid contents at spherical plant stage, the glutathione content at spherical plant-fast growing stage, and the production rate of superoxide anion free radicals (O^-.₂). To increase the application rate of controlled-release compound fertilizer could not only improve the antioxidant ability of flue-cured tobacco, but also promote the accumulation of nitrogen, phosphorus, and potassium in leaf.

Effects of NaCl stress on ion contents in different organs of maize (Zea mays L.) seedlings.

2011, 30(08):  1654-1661. 

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A water culture experiment was conducted to study the changes of Na⁺,K⁺, Ca²⁺, Mg²⁺, and Cl^- contents in different organs of maize seedlings under NaCl stress. With increasing concentration of NaCl in the medium, the Na⁺ and Cl^- contents and Na⁺/K⁺ and Na⁺/Ca²⁺ ratios in different organs of maize seedlings increased rapidly, and the change extent of the Na⁺, K⁺, and Cl^- contents was in the order of root > mature sheath > young blade > mature blade, suggesting that maize seedling’s root was most easily affected by environment ion concentration, while blade was less affected. Under NaCl stress, the Ca²⁺ and Mg²⁺ contents in seedling’s root decreased while those in mature blade increased, but the Mg²⁺ content in mature blade sheath had no obvious change. The seedlings had Na⁺-exclusion mechanism, presenting definite salt-tolerance. The Na⁺ was mainly accumulated in root and mature blade sheath, and less transported to mature and young blades. The mature blade sheath also had Cl^- exclusion capability.

Comparative analysis on the fitting effect of different models of Koelreuteria bipinnata var. integrifoliola rapid light curves.

2011, 30(08):  1662-1667. 

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By using gas analyzer Li-6400, the foliar gas exchange and chlorophyll fluorescence of Koelreuteria bipinnata var. integrifoliola were measured under the CO₂  concentrations  of 380 and 600 μmol·mol^-1, and the measured curves were fitted by different models. The results showed that the maximum electron transport rate fitted by rectangular hyperbola and double exponential equation were far higher than the measured data, rectangular hyperbola, non-rectangular hyperbola, and single exponential equation could not fit the rapid light curve with dynamic down-regulation of PSⅡ, and only double exponential equation and modified rectangular hyperbola could fit the rapid light curve with dynamic down-regulation of PSⅡ and correctly calculate the saturation irradiance, indicating that modified rectangular hyperbola could not only well fit the rapid light curve of K. bipinnata var. integrifoliola, but also make the simulated maximum electron transport rate and saturation irradiance accord with the measured data. Moreover, modified rectangular hyperbolic model could judge whether the simulated electron transport rate and CO₂ assimilation synchronously reached the maximum values through fitting the rapid light curves and light response curve of plant photosynthesis.

Seed dispersal and predation of Castanopsis sclerophylla by small rodents in habitats with different disturbance intensity.

2011, 30(08):  1668-1673. 

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In this study, the Castanopsis sclerophylla seeds in three habitats under slight, moderate, and serious disturbances in Qiandaohu area of Zhejiang Province were tagged and tracked to investigate the impacts of disturbance intensity on the predation and dispersal of C. sclerophylla seeds by rodents. The rodents trapped were identified as the members of Niviventer fulvescens. In the three habitats, all the seeds were eaten in situ or dispersed by the rodents within 2 days. In the habitat under moderate disturbance, the seeds eaten in situ had the highest percentage (37.8% of identified seeds). The seed dispersal distance in the three habitats was mostly <5 m, with the largest being 24.76 m, and the seed dispersal all presented negative exponential distribution, with no significant difference among the habitats. The fate (eaten in situ or dispersed) of sound and infested seeds in the three habitats had no significant difference, but the maximum dispersal distance of sound seeds was significantly larger than that of infested seeds. Except in the habitat under moderate disturbance, where the mean dispersal distances of sound and infested seeds had no significant difference, the mean dispersal distances of sound seeds in the other two habitats were significantly larger than those of infested seeds, indicating that rodents had definite capability in distinguishing sound and infested C. sclerophylla seeds.

Egg reflectance spectra of Chinese Pond Heron (Ardeola bacchus) in Lingao and Chengmai of Hainan Island, South China.

2011, 30(08):  1674-1677. 

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Fiber spectrophotometer and avian visual modeling were adopted to quantitatively analyze the egg color of Chinese Pond Heron (Ardeola bacchus) in Linao and Chengmai of Hainan Island during the breeding season from April to July, 2009. The egg reflectance spectra showed that the wave crest was located on the range of medium wave, with a peak on green light zone. The blue-green egg color of A. bacchus could be an adaptation to predation, nesting habitat, or sexual selection by male. The analysis based on avian visual modeling indicated that the egg chroma, brilliance, and hue UV had no significant differences between Chengmai and Lingao populations, but the hue RGB was significantly different. Robinson Project showed that the variation of egg hue RGB was larger for Chengmai population than for Lingao population, possibly due to the difference in brood parasitism pressure or nest habitat characteristics between Chengmei and Lingao.

Avian diversity and bird strike avoidance at Wuhai civil airport in Inner Mongolia.

2011, 30(08):  1678-1685. 

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Aimed to reduce the accident of potential bird strike at Wuhai civil airport, an investigation was made on the bird communities in 7 habitat types in the airport and its surrounding areas from August 2009 to July 2010, with the avian diversity indices analyzed. A total of 106 avian species belonging to 37 families and 16 orders were recorded, of which, 78 species were native progenitive, and 28 species were non-progenitive. Based on the importance value, and combined with distribution coefficient, grouping behavior, and the behavior of traversing or flying above the runway, the 106 species could be divided into four types of hazard grades, i.e., catastrophic hazard, serious hazard, substantial hazard, and minor hazard. According to the investigation data and the analysis of the main environmental factors attracting birds, the countermeasures for bird strike avoidance at the airport were proposed.

Breeding behavior of common coot (Fulica atra).

2011, 30(08):  1686-1690. 

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An investigation was conducted on the breeding Fulica atra population in Anbanghe Nature Reserve and Longfeng wetland of Heilongjiang Province from April to September, 2008 and 2009. The F. atra in breeding season built three kinds of nest structures, i.e., display platform, egg nest, and brood nest. Both the female and the male participated in the construction of these structures, and protected their territory. The nest height and depth increased with clutch size, but the nest diameter didn’t. The clutch size decreased with the delay of breeding time, with a mean value of 8.77±0.24 (n=75). Both the female and the male made incubation, and the female consumed more time in each incubation event. The female and the male nursed the nestlings together, and some of the young birds were fed by their parents until at sub-adult stage. F. atra was omnivorous. The food list was mainly made up of vegetations, but also contained some animals.

Influence of starvation on juvenile Paralichthys olivaceus compensatory growth, biochemical composition, and energy budget.

2011, 30(08):  1691-1695. 

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By using indoor re-circulating system, this paper studied the compensatory growth, biochemical composition, and energy budget of juvenile Japanese flounder (Paralichthys olivaceus) starved for various days and re-fed with trash fish and formulated diets at 23.0±1.0 ℃. The experimental groups S1F5 and S5F25 all had complete compensatory growth. The compensatory growth of group S1F5 was primarily attributed to the increase of feeding rate, while that of S5F25 was heavily dependent on the improvement of food conversion efficiency. After compensatory growth, there were no significant differences in the biochemical composition of the fish between treated groups and the control (P>0.05). Under starvation, the proportion of energy intake for growth tended to increase, while the proportion of energy for excretion and metabolism energy tended to decrease.

Macrobenthos community structure and its spatial distribution in Erhai watershed lakes.

2011, 30(08):  1696-1702. 

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In May 2009, an investigation was conducted to understand the macrobenthos community structure and its relationships with water environmental factors in Erhai Lake and in three small lakes (Haixihai, Cibihu and Xihu) in Erhai watershed. In Erhai Lake, the mean density of macrobenthos was 1556 ind·m^-2, and the biomass was 8.9 g·m^-2. The macrobenthos community was dominated by Chironomus sp., Limnodrilus hoffmeisteri, and Radix sp., with the relative abundance being 43.5%, 39.5%, and 8.6% respectively. The biomass was mainly contributed by Corbicula largillierti, Radix sp., and Chironomus sp. The spatial distribution of macrobenthos community based on GIS interpolation showed that the density was the highest in the north region of Erhai Lake, the biomass was the highest in the littoral zone of the middle region, both the density and the biomass were relatively low in the south region, and the Shannon diversity index was higher in the littoral zone. In the three small lakes, the main taxa were Nematoda, Chironomidae, Tubificidae and Chaoboridae. Both the density and the biomass had the maximum values (260.8 ind·m^-2 and 1.14 g·m^-2, respectively) in Cibihu Lake. CCA analysis showed that the total phosphorous and Ca²⁺ concentrations in water body had significant effects on the macrobenthos community, with the contribution rate being 34% and 27%, respectively. The Xihu Lake nearest to Erhai had the similar macrobenthos community type as Erhai Lake, mainly because of the relatively high total nitrogen concentration in the water. Compared with historical data, the proportions of Oligochaete and Chironomid in Erhai Lake continued to increase, which implied that the organic pollution in the Lake was further intensified.

Soil erosion in a small watershed in water source areas of Beijing and Tianjin: Spatial simulation.

2011, 30(08):  1703-1711. 

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Aiming at the fragile ecological environment and the strong spatial variability and unpredictable occurrence of soil and water loss in the water source areas of Beijing and Tianjin, a case study was conducted on the soil erosion pattern and its modulus in the Dongbeigou watershed in Pingquan County of Hebei Province by using geographic information system (GIS) and Chinese Soil Loss Equation (CSLE), and the simulation precision of the CSLE was tested. The CSLE had a coefficient of determination higher than 0.85, being highly credible, and the watershed had a soil erosion modulus 2359.24 t·km^-2·a^-1, belonging to light degree erosion. 92.1% of the total soil loss came from the areas with a slope >15°. The soil erosion modulus increased gradually with slope, but showed a decreasing trend when the slope was >45°. A highly spatial heterogeneity was observed in the soil erosion modulus, being the highest (6112.90 t·km^-2·a^-1) for sloping cropland. Degraded grassland occupied 33.2% of the total area, but its soil erosion amount accounted for 74.9% of the total. 59.3% of soil erosion was from sunny and half-sunny slopes, and only 16.2% of it came from shady and half-shady slopes. This study provided a technical basis for applying CSLE to assess the soil erosion in the water source areas of Beijing and Tianjin, and offered scientific reference for the soil and water conservation in the region.

Impacts of extreme rainfall on soil erosion and tree-falling in secondary forest ecosystems in mountainous regions of eastern Liaoning Province, Northeast China.

2011, 30(08):  1712-1719. 

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In order to make clear the damage in secondary forest ecosystems after extreme rainfall, a comprehensive investigation was conducted on the disturbances induced by ertreme rainfall in july-August, 2010 in the  secondary forest ecosystems with different forest types and sites at the Qingyuan Experimental Station of Forest Ecology, Institute of Applied Ecology of Chinese Academy of Sciences in a mountainous region of eastern Liaoning province, China. Extreme rainfall induced serious soil erosion and a great deal of fallen trees, and produced slope debris flow in many places. The seriously damaged areas were those with steeper slopes and higher height differences. There was a negative correlation between the quantities of erosion gully and debris flow, and the shrub coverage. Litter layer had definite inhibitory effect on soil erosion. The number of fallen trees varied with tree species, among which, Fraxinus mandshurica, Larix olgensis, and Betula platyphylla had larger number of fallen trees than the other tree species. Compared with forest lands, non-forest land was more seriously damaged. Based on these results, the likely impacts of extreme rainfall on the stand characteristics, site conditions, and succession processes in secondary forest ecosystems were discussed.

Characteristics of agricultural non-point source nitrogen and phosphorus losses in a typical small watershed in Three Georges Reservoir area.

2011, 30(08):  1720-1725. 

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This paper studied the time series variations of agricultural non-point source nitrogen and phosphorous losses and their relationships with rainfall-runoff in the Daijiagou small watershed (0.67 km²) in Three Georges Reservoir area, based on the 2007-2009 field observation data. In 2007-2009, the peak values of the rainfall and runoff in the watershed had the same variation trend, with the correlation coefficient as high as 0.904. The total nitrogen (TN) and total phosphorus (TP) losses also showed a same variation trend, but the TN loss was more sensitive to the variation of rainfall-runoff, as compared to TP loss. The TN loss fluctuated with rainfall-runoff, but the TP loss showed an increasing trend year by year. The variation pattern of N/P ratio accorded with that of TN concentration, and showed a good coupling relationship with the runoff fluctuation. The peak time of the cumulative percentage of rainfall-runoff was not consistent with that of TN and TP losses, suggesting that the agricultural non-point source nitrogen and phosphorous pollution in the watershed was of random and dispersive, and there was no strict parallelism relationship between the nitrogen and phosphorous pollution.

Cassava’s ethanol productive potential and its spatial distribution in China.

2011, 30(08):  1726-1731. 

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In this paper, the cassava’s ethanol productive potential and its spatial distribution in China were analyzed, based on the climatic, topographic and soil data, and by the method of ArcGIS 9.2 spatial analysis. In this country, the regions suitable for planting cassava and with the highest cassava’s ethanol productive potential mainly distributed in the southern provinces such as Guangxi, Guangdong, Fujian, Yunnan, Jiangxi, and Hainan. However, the suitable but unused lands for cassava in these regions were quite small, only 1.53×10.4 hm², and the cassava’s ethanol productive potential from these lands could only satisfy 1.0% of the China total demand for E10 ethanol gasoline. To fully satisfy the present demand for E10 ethanol gasoline in China, the total area for planting cassava would be expanded 4.7-5.7 times, which is hard to achieve, considering China’s food security. Therefore, the prospect that the present cassava’s ethanol production in China could meet the future demand for bioethanol of the country would be not optimistic. It was suggested that in the development planning of cassava ethanol, our related institutions and industries should fully consider the availability of raw materials, and not enlarge the cassava ethanol production blindly.

Spatial pattern optimizing of apple orchard in mountainous area based on GIS.

2011, 30(08):  1732-1737. 

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Qixia City of Shandong Province is one of the major apple production areas in China, while light and heat conditions and terrain are the key factors affecting the distribution of local apple orchard and the apple quality. It is necessary to optimize the local land use pattern of apple orchard, based on the principles of ecological suitability for the agricultural structure adjustment of the City. On the basis of the simulation on the spatial distribution of light and heat conditions and topographical parameters, and choosing the present land use types as the landscape medium surface, this paper established a minimum cumulative resistance (MCR) model by using GIS technology, and explored the technical approaches for the optimization of apple orchard land use in the mountainous area of Qixia City. Four zones were divided, i.e., most suitable, highly suitable, suitable, and the sub-suitable, occupying 20466, 38392, 97367, and 41301 hm², respectively. The acreage of the most and highly suitable zones for apple planting was 29% of the total. This study showed that the MCR model provided decision-making basis for apple industry development and agricultural structure adjustment of Qixia City.

Screening and fungistatic activity of an endophytic bacterial strain from wheat against Fusarium graminearum.

2011, 30(08):  1738-1743. 

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In this paper, the population density of endophytic bacteria in the wheat plants collected from Huaibei City of Anhui Province was investigated, and the endophytic bacteria were screened, with their fungistatic activity determined. The population density of endophytic bacteria in wheat root, stem, and leaf was 7.01×10⁵, 4.26×10⁵, and 0.94×10⁵ CFU·g^-1 fresh weight, respectively, and a total of 131 endophytic bacterial strains were isolated from the health wheat plants. By using dual culture technique, 6 strains with antagonistic effect on Fusarium graminearum were screened, accounting for 4.58% of the isolated endophytic bacteria. The strain HB022 from wheat root had the best fungistatic effect, with an inhibition zone of radius 17.0 mm. Based on the morphological, physiological, and biochemical characteristics as well as the sequencing of 16S rDNA, the strain HB022 was preliminary identified as Paenibacillus polymyxa. Fungistatic assay showed that the 100-times diluted culture filtrate of strain HB022 was effective in inhibiting the mycelium growth of F. graminearum, and the 5-times diluted culture filtrate completely inhibited spore germination, suggesting that the endophytic P. polymyxa strain HB022 had the potential in biological control of F. graminearum.

Threshold analysis of water blooms in Baiyangdian wetlands.

2011, 30(08):  1744-1750. 

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Threshold analysis of water body eutrophication can provide scientific basis for controlling water bloom and defining pollutants rational control level. Taking the Baiyangdian wetlands as the case, and by using 2000-2009 water quality monitoring data, the main indices characterizing the water body eutrophication of the wetlands were clustered by principal component analysis, and, using chlorophyll a as dependent variable, and water pH, temperature, transparency, COD_cr, total nitrogen, total phosphorus, ammonia nitrogen, nitrate nitrogen, and dissolved inorganic phosphorus as independent variables, the multiple linear relationship of chlorophyll a and water quality indices was established by stepwise regression to determine the thresholds of water blooms in the wetlands. The Baiyangdian wetlands could be categorized into two kind water areas, i.e., low dissolved oxygen and high nutritional, and unstable. With 30 μg·L^-1 of chlorophyll a as the threshold of water bloom, the COD_cr concentration in the low dissolved oxygen and high nutritional water area should be controlled at 37.31 mg·L^-1, and the total phosphorous concentration in the unstable water area should be at 0.12 mg·L^-1.

Spatial distributions of water body nitrogen and their relations with environmental factors in two reservoirs in Xiamen during winter.

2011, 30(08):  1751-1756. 

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This paper probed into the spatial distribution patterns of nitrogen (N) in the water bodies of Hubian and Shidou-Bantou reservoirs in Xiamen during winter, and analyzed the relationships of the N forms in the water bodies with environmental factors, aimed to provide scientific bases for the prevention and treatment of the water pollution of the reservoirs. The average concentrations of total N in the water bodies of Hubian reservoir and of the Shidou and Bantou sections of Shidou-Bantou reservoir were 1.36, 1.44, and 1.45 mg·L^-1, respectively, with the pollution source being exogenous for the Hubian reservoir whereas endogenous for the Shidou-Bantou reservoir. Inorganic N was the major N form in the two reservoirs, accounting for 61.7% and 58.0% of the total N in Hubian and Shidou-Bantou reservoirs, respectively. The inorganic N in Hubian reservoir was mainly NO₃^--N, and that in Shidou-Bantou reservoir was mainly NH₄⁺-N. In Hubian reservoir, the NH₄⁺-N was positively correlated with NO₃^--N but negatively correlated with DO; and in the Bantou section of Shidou-Bantou reservoir, the NH₄⁺-N was positively correlated with transparency but negatively correlated with pH.

Phytoplankton community composition and its relationships with the environment in Shantou Harbor of South China.

2011, 30(08):  1757-1765. 

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Based on the monitoring data of the eco-environment in Shantou Harbor from March 2009 to March 2010,this paper studied the composition of phytoplankton community and its sensitivity to the environment in the Harbor. A total of 322 phytoplankton species were identified, including 234 diatom species, 141 fresh-water and brackish water species, and 64 red tide species.The average abundance, Shannon index, and evenness index of the community were 3127.6×10⁴ cells·m^-3, 2.53, and 0.57, respectively, and Skeletonema costatum and Oscillatoria sp. were the dominant species throughout the year, with the dominance index being 0.066 and 0.038, respectively. There was a significant positive correlation between phytoplankton community composition and water temperature (r=-0.699, P<0.01), and the phytoplankton growth was mainly limited by water transparence. The relevance degree of phytoplankton composition and environmental factors showed that upstream input was an important source of Shantou Port pollutants, and the multi-scale and Pearson correlation analyses indicated that water temperature, salinity, and pH were the main factors affecting the phytoplankton community composition.

Niche characteristics of main plant species in spruce-fir forests in Changbai Mountains.

2011, 30(08):  1766-1774. 

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By using TWINSPAN, the 23 sampling plots of spruce-fir forests in Changbai Mountains were divided into eight community types, and, taking this division as one-dimensional resource state, the niche characteristics of 12 main trees, 13 main shrubs, and 18 main herbs in the spruce-fir forest communities were analyzed by using Levins and Hurlbert formulae of niche breadth and Pianka formula of niche overlap. In tree layer, Abies nephrolepis and Picea jezoensis had the biggest niche breadth, and were the main constructive species of the forest communities in this region. In shrub layer, Euonymus pauciflorus and Acer ssp. had larger niche breadth than other species. In herb layer, Dryopteris crassirhizoma, Oxalis acetosella,and Maianthemum bifolium had higher niche breadth, showing that these species widely distributed under the dense canopy of the forests, and had strong capability to adapt to the environment. The populations with larger niche breadth could produce smaller niche overlap, while those with smaller niche breadth would have larger niche overlap, mainly depending on the biological characteristics of plant species and their demands for environmental resources. From the viewpoint of the distribution pattern of niche overlap, there generally existed niche overlaps among main populations, but the niche overlaps were mostly at low level, indicating that the interspecific competition generated by utilizing same resources or occupying specific resources was not intense, and the environmental resources could be sufficiently shared by different populations. The spruce-fir forest communities in Changbai Mountains were at relatively stable stage.

Interspecific association and correlation of main plant species in subalpine meadow of Zibai Mountain.

2011, 30(08):  1775-1780. 

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By using variance ratio (VR) of overall association, χ²-test, Jaccard association index, Pearson coefficient, and Spearman rank coefficient, this paper studied the interspecific association and correlation of 20 main plant species in the subalpine meadow of Zibai Mountain. Among the 20 species, few pairs had significant or very significant interspecific association (correlation). The ratios of positive and negative associations (correlations) by χ²-test, Pearson coefficient, and Spearman rank coefficient were 0.85, 0.61, and 1.02, respectively, suggesting that the plant community was relatively stable. According to Spearman rank correlation coefficient, the 20 species were divided into 4 ecological groups. In each group, the species had the similar ecological demands and the similar ways of utilizing resources; among the groups, there was an obvious transform and succession trend. Positive association (correlation) occurred between the species pairs having similar biological traits and similar ecological adaptability to habitats, whereas negative association (correlation) occurred between the species pairs having different biological features and different ecological adaptability to habitats.

Typical forest ecosystem services in Baimaxueshan National Nature Reserve.

2011, 30(08):  1781-1785. 

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Ecosystem service is currently a hot research topic in ecology, especially for critical regions. Located at the southern edge of Qinghai-Tibet Plateau, the Baimaxueshan National Nature Reserve in Yunnan Province is a biodiversity hotspot with special geographical position. In this study, three typical categories of forest ecosystem services (biomass and productivity, water conservation, and nutrient cycling) in the Reserve were evaluated. The forest total biomass was 2215.86×10⁴ t, productivity was 171.84×10⁴ t·a^-1, water-holding capacity was 11964.56×10⁴ m³, and annual absorption of N, P, and K was 26025.94 t, 2638.57 t, and 12016.85 t, respectively, indicating that the forests in Baimaxueshan Nature Reserve had significant ecological benefits, and had importance in maintaining the ecological safety of the local and surrounding areas.

Landscape aesthetic assessment of old-tree communities in Jiuhua Mountain Scenic Area of Anhui Province.

2011, 30(08):  1786-1792. 

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Taking the old-tree communities in Jiuhua Mountain Scenic Area as the object, the landscape photos and sampling plots information of 26 representative old-tree forest stands and 45 contrast forest stands were collected, and the scenic beauty values of the stands were acquired by using scenic beauty estimation (SBE) method. The landscape elements of old-tree communities were quantified by semantic differential (SD) method, and the relationships between scenic beauty values and specific landscape elements were evaluated with multi-regression model. The old-tree communities had significantly higher scenic beauty values than the other forest stands. In old-forest stands, the test trees had higher feedback values to the landscape elements such as arrangement of trees, light perception, and variation of tree size. The main elements affecting the landscape aesthetic value of old-tree community were the trunk form, richness of color, arrangement of trees, uniformity of ground plants, landscape gradation, natural pruning, and uniformity of shoots and leaves in tree layer. F-test showed that the model established by these landscape elements was reasonable and feasible.

Habitat degradation features of Père David’s Deer Natural Reserve in Dafeng of Jiangsu Province, East China.

2011, 30(08):  1793-1798. 

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To understand the degradation mechanism of Père David’s deer habitat, an investigation was made on the plant community characteristics in Père David’s Deer Natural Reserve in Dafeng of Jiangsu Province. In the Reserve, the community similarity index of the grassland inside and outside the fence was low. The aboveground biomass, species number, richness index, Shannon index, and evenness index of the plant community inside the fence were all lower than those outside the fence, whereas the ecological dominance index of the plant community was in adverse. The further the distance between grassland communities, the lower the plant community similarity index was. Inside the fence, the species dominance of Pennisetum alopecuroides was absolutely dominant. With the increasing distance from the activity center of Père David’s deer, the plant community evenness index increased, and the percentage of P. alopecuroides aboveground biomass in total plant community as well as the population characteristic values of P. alopecuroides declined. It was considered that the fire for killing Haemaphysalis longicornis could be one of the major reasons causing the habitat degradation. The results could serve as the theoretical references for ecological restoration of Père David’s deer habitat.

Impacts of water conservancy project on Yalu River delta.

2011, 30(08):  1799-1804. 

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Based on the TM images in 1997 and 2007, and by using GIS spatial analysis, this paper analyzed the impacts of water conservancy project on Yalu River delta in last ten years. In the meantime, with statistical methods and by using Markov Model, the evolvement of Yalu River delta in the next 20 years was predicted. The results showed that water conservancy project reduced the sediments transported to the River, and the delta eroded intensely. Due to extensive reclamation, the west channel of Yalu River was silted up severely. In the future, Yalu River delta would be eroded more seriously, and, when the erosion arrived at stable state, the waters area in the delta would take up 44。9% of the total, and the landscape matrix would be changed.

Urban green space land suitability and its spatial distribution in Shenyang City of Northeast China.

2011, 30(08):  1805-1812. 

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Land suitability analysis is the necessary premise for spatial distribution planning of urban green space. Based on the status investigation and statistical data, and by using multi-factors evaluation method, this paper evaluated the land suitability of green space in Shenyang City. The weights of affecting factors were decided by analytic hierarchy process (AHP) and pair-wise comparison, the suitable area for green space construction was analyzed based on the spatial analysis module in ArcGIS, and the identified land resource for green space construction was determined for the green space system planning and development direction in Shenyang in the future. In the City, the most suitable area for urban green space construction took 11.1%, suitable area took 19.2%, basically suitable area took 23.3%, unsuitable area took 29.5%, and unavailable area took 16.5%. According to the results, suggestions were provided on the spatial distribution of the construction of urban ventilation, urban group green space, and urban green space ecological network to highlight the urban green space system planning of Shenyang.

Research advances in plant density-dependent regulation and its responses to environmental change.

2011, 30(08):  1813-1821. 

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To study the plant density-dependent regulation pattern is of significance to the development of plant ecology and to give guidance to the rational density in forestry, agriculture, animal husbandry, and restoration of degraded ecosystems. This paper reviewed the recent researches on the -3/2 and -1/2 self-thinning rules, the instability and dispute of self-thinning exponent, and the relationships between self-thinning rules and density regulation exponent, summarized the responses of density regulation exponent to environmental changes such as water gradient, salt concentration, altitude, and light condition, and discussed the positive and negative interactions among individual plants and the relationships of plant density regulation mechanisms in ecological field with plant morphology, coverage and environmental changes. The study of self-thinning exponent had experienced invariable, variable, and change with environment. The future research trend of plant density-dependent regulation pattern was proposed from the aspects of WBE (West, Brown and Enquist) model and metabolic ecological theory (MET), plant neighbor effect, belowground and aboveground integration, rhizospheric microbial regulation to plant interaction, and combination of macro and micro levels.

Responses of stem/branch respiration to environmental change: A review.

2011, 30(08):  1822-1829. 

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Stem/branch respiration contributes about 8% of the total ecosystem respiration, being one of the most important components of forest carbon budget. In recent 10 years studies, specific respiration chamber with complex system was applied to measure the stem/branch respiration. However, it’s still difficult to precisely estimate the stem/branch respiration at cell, tissue, individual, and stand scales. It is becoming a major trend to estimate the CO₂ flux from the  internal and external stem/branch, using the combination of CO₂ microelectrode technology and infrared gas analyzer (IRGA) method. Generally, the stem/branch respiration rate increases with elevated atmospheric CO₂ concentration and temperature, but it’s still unclear whether the stem/branch　respiration acclimates to the elevated CO₂ concentration and temperature. The Q₁₀ value of stem/branch respiration, ranged from 1.0 to 4.3, could be affected by measurement method, season, tree age, and stem diameter. In addition, the stem/branch respiration rate decreased with increasing drought stress, and increased abruptly with the following rewetting process. The management practices, including fire, fertilization, irrigation, pruning, and girdling, could also affect the stem/branch respiration rate. Therefore, four research priorities were proposed, i.e., 1) sources and fate of the CO₂ release from stem/branch respiration and its measurement standard, 2) biological mechanisms of the responses of stem/branch respiration to environmental change, 3) acclimation of stem/branch respiration to environmental changes, and 4) integrated application of stem sap flow measurement, isotopic tracing, and CO₂ microelectrode technology in measuring stem/branch respiration.

Main ecological service functions in riparian vegetation buffer zone: Research progress and prospects.

2011, 30(08):  1830-1837. 

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Riparian vegetation buffer zone is the ecotone between aquatic and terrestrial ecosystems, which has unique spatial structure and ecological service functions, being a research hotspot in ecological and environmental sciences. In this paper, the researches on the ecosystem structure of the riparian zone and its main ecological service functions in biodiversity conservation and non-point nitrogen pollution prevention were summarized and analyzed. Owing to the complicated structure, multiple interference factors, and high spatial-temporal heterogeneity of the riparian zone, more theoretical and case studies are needed to improve the scientific management of riparian ecosystem. It was prospected from the viewpoints of ecosystem ecology and landscape ecology that further researches in the following fields would be made: (1) effects of human disturbances such as the spatiotemporal change of land use on the biodiversity and eco-environment in the riparian zone, (2) effects of different riparian vegetation buffer zones and regional environmental characteristics on the purification mechanisms and control processes of non-point nitrogen pollution, and (3) development of ecosystem management models adaptive to our regional and environmental characteristics, and quantitative study of dynamic changes in riparian ecosystem structure, process, and function as well as their relationships with and impact mechanisms of human disturbances, based on the small-scale and long-term observation in fixed location and mechanism study and on the comprehensive usage of mathematical methods, remote sensing, and GIS, with the aim of providing scientific evidences and management policies for the sustainable development of regional economy.

Biological traits and their ecological significances of parasitic plants: A review.

2011, 30(08):  1838-1844. 

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Parasitic plants are an important component of terrestrial ecosystems, and widely distributed in most terrestrial ecosystems. They totally or partially depend on the host plants to absorb organic and/or mineral nutrients and water to complete their life cycle. Parasitic plants not only have direct effects on their host plants, but also give influence on the whole plant community via affecting the competition between their host and non-host plants. At individual level, parasit
ic plants generally show negative effects on the growth of their host plants, and often result in severe financial losses. As a result, the control of parasitic plants has been the focus of relevant research. At community level, however, parasitic plants have positive effects on promoting biodiversity. By this token, parasitic plants have a potential to be used in plant community engineering. Whether to control or to utilize parasites, it is essential to understand their biological traits. This paper reviewed the biological traits of parasitic plants, including parasitism type, host range and preference, host recognition, and haustoria formation and functions. Also, the impacts of parasitic plants on their hosts and on the community structure where the host plants occurred were discussed. The research gaps in relevant fields were pointed out, and the possible research topics were suggested.

Responses of Schizosaccharomyces pombe to environmental stress: A review.

2011, 30(08):  1845-1850. 

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Schizosaccharomyces pombe is an excellent model organism widely applied in the study of cell-cycle control, mitosis and meiosis, DNA repair and recom
bination, and checkpoint controls important for genome stability. Because of its close relationship with human beings evolution, S. pombe has recently being applied in the researches on its responses to environmental stresses. A majority of the stresses can directly or indirectly induce the reactive oxygen species (ROS) of S. pombe. This paper summarized the basic characteristics of S. pombe genome, proteome, and cellular structure, reviewed the research progress in the responses of S. pombe to environmental stresses, e.g., physical radiation, oxidants, heavy metals, and hormones, etc., and analyzed the response pathways as well as the components possibly involved under different environmental stresses. Further studies on the better application of the model organism in environmental assessment were prospected.