Table of Content

10 September 2012, Volume 31 Issue 09

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Articles

Dynamics of xylem sap flow of two Magnoliaceae tree species in relation to environmental factors.

CAI Xi-an**, ZHAO Ping, ZENG Xiao-ping, ZHU Li-wei, ZOU Lü-liu, MEI Ting-ting, YU Meng-hao

2012, 31(09):  2163-2169. 

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To understand the water use characteristics of Magnoliaceae is of significance to improve its survival rate in exsitu conservation. By using thermal dissipation probe, this paper studied the dynamics of the diurnal and seasonal sap flow densities of Alcimandra cathcartii and Michelia macclurei as well as the relationships between the dynamics and environmental factors in Guangzhou of South China. A single peak pattern was observed in the diurnal variation of the transpiration of the two species, but there was still a visible sap flow after sunset. In January 2009, the daytime maximum sap flux density per unit basal area (F_d) of A. cathcartii (25.00±7.35 g·m^-2·s^-1) was obviously higher than that of M. macclurei (6.35±1.46 g·m^-2·s^-1); in July 2008 and January 2009, the daytime mean F_d (6:00-18:00) of A. cathcartii was also obviously higher than that of M. macclurei. Partial correlation analysis indicated that the responses of the transpiration of the two species to environmental factors varied with seasons, being stronger in dry season (October and January) than in wet season (April and July). The wholeday transpiration per unit area at breast height was an effective indicator to reveal the differences in the diurnal water consumption for transpiration among the individuals and the tree species. The water consumption of A. cathcartii was greater than that of M. macclurei, and thus, more attention should be paid to A. cathcartii in its exsitu conservation because of its high physiological demand for water.

Effects of exotic tree species Larix principisrupprechtii introduction on forest community in Qinling Mountains of Northwest China.

PENG Shun-lei1,2, WANG De-xiang1**, CHAI Zong-zheng

2012, 31(09):  2170-2176. 

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By the method of plot investigation, a comparative study was made on the differences in the community characteristics among the exotic tree species Larix principisrupprechtii plantation, indigenous tree species Pinus armandii plantation, and P. armandii secondary forest in Huoditang forest area of Qinling Mountains. The similarity coefficient between L. principisrupprechtii plantation and P. armandii secondary forest was only 0.11, and the species number in the P. armandii secondary forest and P. armandii plantation was significantly greater than that in L. principisrupprechtii plantation (P<0.01). The Margalef index, Simpson index, ShannonWiener index, and Pielou evenness index in the arbor, shrub, and herb layers of P. armandii secondary forest and P. armandii plantation were significantly higher than those in L. principisrupprechtii plantation (P<0.001), but the four diversity indices in the shrub layer and herb layer in P. armandii secondary forest and P. armandii plantation had less difference (P>0.05). The compose index (CI) was the lowest (0.3) in L. principisrupprechtii plantation, 3.5 in P. armandii plantation, and the highest (5.2) in P. armandii secondary forest, showing a significant difference among the three forest types (P<0.001). This study indicated that exotic tree species introduction led to the decrease of species abundance, species diversity, and stand’s naturalized degree in the forest community in Qinling Mountains, while natural secondary forest succession or indigenous tree species plantation were more beneficial to the restoration of understory vegetation than exotic tree species plantation.

Dynamics of species diversity and interspecific association in shrub layer of naturally restored woodland on northern slope of Qilian Mountains, Northwest China.

SHI Fu-xi, ZHAO Cheng-zhang**, GAO Fu-yuan, REN Heng, SHENG Ya-ping, SHI Li-li

2012, 31(09):  2177-2183. 

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By substituting spatial difference for time change, seven major natural communities representing the succession series of degraded woodland from herbage community to tree community at altitudes from 2468 to 2761 m on the northern slope of Qilian Mountains were selected to measure the species diversity in shrub layer by multiple indices, and the species overall interspecific association and dominant species interspecific association in the shrub layer of the communities at different succession stages were analyzed by variance analysis and χ² test. Up to 19 shrub species belonging to 10 families and 16 genera were investigated. The results showed that in shrub layer, the species number and Gleason index were the greatest in Picea-Betula community, the Simpson index and Shannon-Wiener index were the greatest in Betula community, the evenness index was the greatest in Potentilla glabra community, and the dominance index was the greatest in Picea crassifolia community. Except for Betula-Populus community, all the other communities had a larger number of shrub species pairs with negative association than with positive association, reflecting the interspecific competition relationship of shrub species in the succession series. With the succession of the communities, the interspecific association of most shrub species pairs changed with succession stage, i.e., insignificant at early stage, significant or very significant at middle stage, and null or insignificant at late stage. The species overall interspecific association was negative in the restored shrub community at early stage and in the broadleaved forest dominated by heliophytes, positive in the mixed coniferous forest dominated by heliophytes, negative in the mixed coniferous and broadleaved forest, and positive in the coniferous forest dominated by mesophytes. The changes in the species diversity and interspecific association among the shrub species pairs in the succession series could be related to the niche separation or niche overlapping caused by the stratification of community structure from the ground to the community’s top crest.

Effects of elevated O₃ and CO₂ concentrations on the membrane lipid peroxidation and antioxidant systemof Oligostachyum lubricum leaves.

ZHUANG Ming-hao, CHEN Shuang-lin**, LI Ying-chun, GUO Zi-wu, YANG Qing-ping

2012, 31(09):  2184-2190. 

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By using opentop chamber, this paper studied the effects of elevated CO₂(700 μmol·mol^-1) and O₃(100 nmol·mol^-1) concentrations and their combination on the leaf membrane lipid peroxidation and antioxidant system of two years old Oligostachyum lubricum. After 30 days exposure to elevated O₃ concentration, the activity of the leaf antioxidant system and the contents of the leaf osmotic adjusting substances increased, the ability of eliminating reactive oxygen production enhanced, but the malondialdehyde content had less change, suggesting that the O. lubricum could tolerate shortterm O₃ stress. After 90 days exposure to elevated O₃, the activity of leaf antioxidant system decreased while the leaf malondialdehyde content increased significantly, and the cell membrane structure was seriously damaged. After 30 days exposure to elevated CO₂ concentration, both the activity of leaf antioxidant system and the contents of leaf osmotic adjusting substances increased, suggesting that O. lubricum had a definite physiological adaptability to high CO₂ oncentrations. After 90 days exposure to elevated CO₂ concentration, the activity of leaf antioxidant system and the contents of leaf reactive oxygen species decreased significantly, and the leaf soluble sugar and protein contents increased, which benefited the growth of O. lubricum. Under the effects of the combination of elevated CO₂ and O₃, the O. lubricum leaves could maintain high levels of antioxidant activity and osmotic adjustment substances contents to effectively regulate the balance between reactive oxygen species production and clearance, indicating that elevated CO₂ could mitigate the oxidative stress in certain degree.

Effects of secondary forest canopy openness on the growth of Pinus koraiensis saplings in eastern Liaoning Province of Northeast China.

MIAO Jie1,2,3, YU Li-zhong1,2**, SUN Yi-rong1,2,3

2012, 31(09):  2191-2196. 

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To understand the effects of light regimes on the height growth  of Pinus koraiensis saplings, an investigation was made under the canopies of secondary forests treated by light thinning (stand A), heavy thinning (stand B), and clear cut (stand C) as well as the currentyear height growth of P. koraiensis under the canopies. The canopy openness on the top of P. koraiensis saplings was measured by hemispherical photographs, and the relationship between the light regimes and the height growth increment of P. koraiensis saplings was established. The light transmittance in stand C dominated by Quercus mongolica was highers, while that in stands A and B dominated by mixed broadleaved species was lower. The major factor limiting the growth of P. koraiensis saplings was the shading of the understory broadleaved trees with a height of 10 m. The height growth increment of the P. koraiensis saplings in stand C was significantly higher than that in stands A and B. There was a significant positive relationship (R²=0.516, P<0.01) between the currentyear height growth increment of P. koraiensis saplings and the canopy openness. It was suggested that to accelerate the positive succession of the secondary forests in eastern Liaoning Province, the canopy openness on the top of P. koraiensis saplings should be modified to more than 30%.

Effects of drought stress on the photosynthesis and growth of Cyclobalanopsis glauca seedlings: A study with simulated hierarchical karst water supply.

ZHANG Zhong-feng1,2, YOU Ye-ming3, HUANG Yu-qing1, LI Xian-kun1, ZHANG Jin-chi2, ZHANG De-nan4, HE Cheng-xin1**

2012, 31(09):  2197-2202. 

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Based on the geological characteristics of karst environment, a simulated hierarchical columniation of water supply (soil layerepikarst layerrock layer) was built up, and a gradient of soil moisture content (severe drought, medium drought, suitable soil moisture, and saturated soil moisture corresponding to 30%-40%, 50%-60%, 70%-80%, and 90%-100% of field moisture capacity, respectively) was installed to investigate the photosynthesis and growth of 2-year-old Cyclobalanopsis glauca seedlings under the simulated karst environment. The results showed that soil drought stress decreased the growth of the seedlings basal diameter and branch significantly (P<0.01), but had less effects on the basal diameter growth when the water in epikarst layer was available. The photosynthesis-light response curve of the seedlings fitted the nonrectangular hyperbola model well, meaning an agreement between the model and the actual response of the seedlings photosynthesis, and the light response curve under different soil moisture conditions had the similar variation trend. The maximum net photosynthetic rate (P_max) and the apparent quantum yield (AQY) of the seedlings under different soil moisture conditions were in the order of saturated soil moisture > suitable soil moisture > medium drought > severe drought. Soil drought stress decreased the light saturation point (LSP) and increased the light compensation point (LCP), but the LSP and LCP changed irregularly when the water in epikarst layer was available.

Effect of exogenous nitric oxide on antioxidant system of Taxus chinensis var. mairei under UV-B stress.

LI De-wen, LI Mei-lan, YU Jing-hua, ZU Yuan-gang**

2012, 31(09):  2203-2208. 

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In order to approach the effect of nitric oxide (NO) on the plant antioxidant system under the stress of UV-B radiation, a pot experiment with 5-year old Taxus chinensis var. mairei seedlings was conducted to study the effect of sodium nitroprusside (SNP) as an exogenous NO donor on the seedlings leaf antioxidant system under elevated UV-B radiation. Four treatments, i.e., CK (control), SNP (+ 0.1 mmol·L^-1 of SNP), UV-B (+4.22 kJ·m^-2·d^-1 UV-B), and UV-B+SNP (+ 0.1 mmol·L^-1 of SNP + 4.22 kJ·m^-2·d^-1 UV-B), were installed, and the leaf hydrogen peroxide (H₂O₂),  malondialdehyde (MDA),
 and  antioxidant concentrations were measured. Elevated UV-B radiation increased the leaf H₂O₂ and MDA concentrations significantly (P<0.05), while exogenous NO addition decreased the H₂O₂ and MDA concentrations and increased the taxol, flavonoids, carotenoids and soluble protein concentrations significantly (P<0.05). Different treatments had different effects on the leaf antioxidase activities. SNP increased the CAT and POD activities significantly (P<0.05), while UV-B and SNP+UV-B increased the POD activity and decreased the CAT and APX activities significantly (P<0.05), as compared with CK. It was suggested that exogenous NO could increase the plant antioxidase activities and antioxidant concentrations and decrease the plant H₂O₂ concentrations and lipid peroxidation, and thereby, could relieve the impact of UV-B stress on plant to a certain extent.

Nutrient use characteristics of Phyllostachys praecox leaves as affected by continuous year soil-surface mulching.

LIU Ya-di1, FAN Shao-hui1**, CAI Chun-ju1, LIU Guang-lu1, XIAO Fu-ming2, ZHANG Da-peng1

2012, 31(09):  2209-2216. 

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To reveal the effects of continuous year soilsurface mulching on the nutrient use characteristics of Phyllostachys praecox leaves, this paper studied the leaf nutrient use efficiency and resorption efficiency in a P. praecox forest during refoliation across three years soil-surface mulching. With the mulching, both the soil nitrogen (N) availability and the P. praecox leaf N use efficiency and N resorption efficiency had a significant increase, showing a higher N-nutrientconserving ability of the forest. The soil phosphorus (P) availability increased significantly but the leaf P use efficiency was in adverse, reflecting the leaf adaptation strategy to high soil P content. There was a significant negative correlation between leaf N and P use efficiency. Opposite to soil N and P, soil potassium (K) had a significantly decreased availability. The leaf K resorption efficiency increased up to 95.8%, suggesting that the forest could maintain normal nutrient circulation through enhancing its leaf K resorption efficiency. The leaf N_m/P_m across the three years soil-surface mulching had a significant decrease, being less than 14, indicating the high capability of P. praecox leaves to absorb soil P within the three years soil-surface mulching. The matured leavesN_m/P_m had no significant correlations with leaf N and P resorption efficiency, and thus, leaf N_m/P_m could not best reflect the nutrient resorption pattern of the P. praecox forest.

Pollination biology and breeding system of Craigia yunnanensis in fragmented habitat.

GAO Ze-rui1, ZHANG Chang-qin2**, HAN Zhi-qiang1, LI Zhong1, WEI Jie1, SHI Hong-lin1

2012, 31(09):  2217-2224. 

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By the methods of field observation and artificial pollination, this paper studied the characteristics of pollination biology and breeding system of endangered species Craigia yunnanensis in the fragmented habitats of Fadou distribution area, Xichou County of Yunnan Province, Southwest China. Each cyme of the C. yunnanensis had 2-9 hermaphroditic flowers, and the lifespan of a single hermaphroditic flower was approximately 3-4 days. There existed certain temporal isolation (dichogamy) and spatial isolation (herkogamy) between the pistils and stamens of each hermaphroditic flower. The outcrossing index (OCI) was >4, and the ratio of pollen to ovule (P/O) was 1381±53. The most frequent and effective pollinator was Chrysomyia megacephala. The fruiting rate of geitonogamous pollination was rather low, and thus, the breeding system of C. yunnanensis was mainly belonged to outcrossing, with partial selfcompatibility, and the pollinator insects were essential. Both the fruit-setting ratio and the seed-bearing ratio under natural conditions were low as 56.67%±3.85% and 6.26%±0.75%, respectively, whereas artificial xenogamous pollination could significantly promote the fruit-setting and seed-bearing ratios (P< 0.01). In the fragmented habitats, the pollinators were lesser, and the pollination efficiency was lower, suggesting that habitat fragmentation affected the early stage reproduction process of C. yunnanensis plants.

Influence of water condition on morphological characteristics and biomass of Calligonum caputmedusae Schrenk seedlings.

SONG Cong1,2,3, ZENG Fan-jiang1,2**, LIU Bo1,2,3, ZHANG Li-gang1,2,3, LUO Wei-cheng1,2,3, PENG Shou-lan1,2,3, Stefan K. ARNDT4

2012, 31(09):  2225-2233. 

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In the desert-oasis transitional zone in southern fringe of Taklimakan Desert, Xinjiang of Northwest China, the mean annual precipitation is only about 35 mm, but occasional strong precipitation sometimes happens, like the event in 2010. How the perennial species adapt to the short-term heavy precipitation is less known. In this paper, a site-specific field investigation was conducted to understand the morphological and growth characteristics of Calligonum caputmedusae Schrenk under different soil water conditions. At seedling period, the morphological characteristics (including plant height, crown width, basal diameter, and root depth) and population density of C. caputmedusae were positively correlated with soil water content, and increasing root/shoot ratio was an effective strategy of C. caputmedusae to adapt to soil water shortage. Especially in July and August, the root/shoot ratio increased with decreasing soil water content. The plants allocated more biomass into aboveground part in their early growth period to compete for light resource, and allocated more biomass into root in the late growth period to explore underground space resources. The seedlings could selfregulate their growth proportion to adapt the environment when soil water content changed. An allometric relationship between plant height and basal diameter was always observed under different soil water condition. To some extent, these results reflected the growth pattern of the C. caputmedusae seedlings under different soil water conditions, and provided theoretical support for the vegetation restoration in the south fringe of the Taklamakan Desert.

Litter biomass and its carbon and nitrogen storage in four subtropical forests in central Southern China.

LU Xiang1,2, XIANG Wen-hua1,2**, REN Hui3, PENG Chang-hui4

2012, 31(09):  2234-2240. 

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Four subtropical forests with similar site conditions in the hilly area of Dashanchong Forest Park in central Hunan Province of China were selected to compare the existing litter biomass and its carbon (C) and nitrogen (N) storage. The litters were collected in the peak time of litterfall. Among the four forests, Cyclobalanopsis glauca-Lithocarpus glaber mixed forest had the highest litter biomass (12.04±3.60 t·hm^-2), followed by Pinus massonianaL. glaber mixed forest (11.65±2.15 t·hm^-2), Choerospondias axillaris forest (9.12±2.30 t·hm^-2), and Cunninghamia lanceolata plantation (8.92±1.80 t·hm^-2). In litter layer, leaf litter had the largest proportion, while fruit litter had the smallest one (<5%). No significant differences were observed in the amounts of the litters with different decomposition degrees. The C concentration of the litters in the four forests ranged from 177.90 to 581.34 g·kg^-1, and the N concentration varied from 5.18 to 15.48 g·kg^-1. The C concentration of the litters decreased significantly with their decomposition degree (P <0.0001). The proportions of the semidecomposed litter and decomposed litter in the forests had a negative correlation  with the litter C/N. The litter C storage in the four forests ranged from 3.37 to 5.69 t·hm^-2, and the N storage varied from 81.52 to 152.18 kg·hm^-2. Because of the low litter decomposition rate and high existing litter amount,P. massoniana-L. glaber mixed forest had the highest C and N storage in its litter layer.

Inhibitory effects of aqueous extracts from mangrove plant Kandelia candel leaves on microalgae.

SUN Zhi-wei1, TIAN Fei1, AN Min2, DUAN Shun-shan1**

2012, 31(09):  2241-2246. 

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Through the measurement of algal cell density, this paper evaluated the allelopathic inhibitory effects of different concentration (0.5, 1.0, and 2.0 g·L^-1) aqueous extracts from the fresh leaves of mangrove plant Kandelia candel on Phaeocystis globosa and Heterosigma akashiwo. The impacts of heat treatment on the allelopathic effects of the extracts were also examined. The leaf extracts of K. candel had significant inhibitory effects on the two microalgae, and the effects were concentration-dependent. In five days, the maximum inhibitory rates of the extracts at 2.0 g·L^-1 on P. globosa and H. akashiwo were 91.6% and 77.0%, respectively. P. globosa and H. akashiwo had different sensitivity to the extracts. The inhibitory effect of the extracts was stronger on P. globosa than on H. akashiwo. Heat treatment decreased the inhibitory effects of the extracts significantly (P<0.05). The extracts damaged the cell membrane of the microalgae, making their cells expanded and broken.

Distribution patterns of sediment chlorophylla in Spartina alterniflora salt marshes at Rudong coast of Jiangsu, East China.

WANG Dan-dan, GAO Shu, DU Yong-fen**, GAO Wen-hua

2012, 31(09):  2247-2254. 

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Sediment chlorophylla (Chl-a) in intertidal zone is an indicator of the primary productivity of microphytobenthos in intertidal ecosystem. In order to understand the distribution patterns of the Chl-a in Spartina alterniflora salt marshes and bare flats at the Rudong coast of Jiangsu, surface (0-8 cm) sediment cores were collected from 11 sites in July and October 2010, with the Chl-a content determined. Except for the sites 1-5 in October, the vertical distribution of the Chl-a at other sites presented a similar trend, i.e., a rapid reduction with the depth in the top 2 cm and little change at the depth of 2-8 cm. The decrease of illumination was a major factor for this pattern. The horizontal distribution of the Chl-a in the salt marshes and bare flats was different between summer and autumn. In summer, the Chl-a content was higher in salt marshes than in bare flats; but in autumn, it was in adverse. Such a difference was due to the combined effects of illumination and sediment grain size. The shading of illumination and the trapping of finegrained sediment by S. alterniflora at its different growth stages varied, which directly affected the growth of benthic microalgae, and further, affected the primary productivity of microphytobenthos in the intertidal ecosystem.

Responses of active oxygen metabolism and osmotica accumulation of Avena nude L. seedlings to NaCl stress.

LIU Jian-xin**, WANG Jin-cheng, WANG Rui-Juan, JIA Hai-yan

2012, 31(09):  2255-2260. 

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A sand culture experiment was conducted to study the effects of NaCl stress on the seedling’s growth, active oxygen metabolism, and osmotica contents of Avena nude L. (cultivar Dingyou No. 6). Six levels (0, 50, 100, 150, 200, and 250 mmol·L^-1) of NaCl were installed. NaCl stress inhibited the seedling growth significantly, and the inhibition was aggravated with increasing concentration of NaCl. The maximum concentration of NaCl that the seedlings could be in resistance to was about 150 mmol·L^-1. With the increasing concentration of NaCl, the leaf O₂^-_· production rate and H₂O₂ and malondialdehyde contents increased dramatically, the activities of superoxide dismutase, guaiacol peroxidase, and ascorbate peroxidase decreased after an initial increase, and the catalase activity increased gradually after a rapid decrease. The NaCl stress decreased the leaf glutathione content markedly, but the ascorbic acid content was less affected. Under NaCl stress, the leaf proline content had a significant increase. With the increasing concentration of NaCl, the leaf Na⁺ content increased markedly, the K⁺ content and K⁺/Na⁺ ratio were in adverse, the plasma membrane H⁺-ATPase activity and the contents of total soluble protein, heatstable protein, and heatunstable protein decreased after an initial increase, the free amino acid content decreased first and increased then, and the soluble sugar content presented a trend of decreaseincreasedecrease. All the results indicated that the imbalance of leaf active oxygen metabolism, the disturbance of leaf Na⁺ and K⁺ homeostasis, and the more consumed energy for osmotic adjustment by accumulated organic solutes under NaCl stress could be the main causes for the growth inhibition of the seedlings.

Effects of sowing date on the growth and tuber yield of potato in semiarid area of loess plateau in central Gansu Province of Northwest China.

ZHANG Kai1,2,3**, WANG Run-yuan1, LI Qiao-zhen3, ZHAO Hong1, WANG He-ling1, GUO Lin3, ZHANG Xiu-yun3

2012, 31(09):  2261-2268. 

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A field experiment with six sowing dates of potato was conducted in Dingxi of Gansu in 2010, and the growth and yield formation of the potato after sowed at different dates were analyzed, aimed to search for the suitable sowing period of potato in semiarid area of the loess plateau in central Gansu under the background of climate change. With the delay of sowing dates, the whole growth period of potato shortened, plant height had obvious change, and the dates corresponding to the peak values of dry matter accumulation rate per plant advanced. Among the test sowing dates, the potato sowed on May 27 had the largest plant height, leaf area index, and dry matter accumulation and maximum accumulation rate per plant, and the tuber fresh weight showed an Svariation curve of “slow-fast-slow”. The dates corresponding to the peak values of tuber fresh weight accumulation rate were also advanced with the delay of sowing dates. The variance analysis and multiple comparisons of the yield data showed that sowing date was the main factor affecting potato yield which was the highest when the sowing date was May 27. The analysis of the meteorological conditions at different growth stages of potato indicated that the suitable sowing period of potato in semi-arid area of the loess plateau in central Gansu was by the end of May or in early June.

Decadal variations of potential cultivation distribution of spring maize in China in 1961-2010.

HE Qi-jin1,2, ZHOU Guang-sheng1,3**, SUI Xing-hua3, SUN Jing-song3

2012, 31(09):  2269-2275. 

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Based on the established model of spring maize cultivation distributionclimate in China, this paper analyzed the decadal variations of the potential cultivation distribution of spring maize in this country in 1961-2010. There was an increasing trend in the potential cultivation distribution of spring maize in China. The optimal cultivation area presented a fluctuating increase, and reached about 5.3×10⁵ km² in last decade; while the suitable cultivation area expanded eastward obviously, and increased by 8.2×10⁵ km² in last 50 years. The northern boundary of the potential cultivation distribution shifted northward, and the maximum northward shift reached about 1.4 degrees in latitude. The results implied that climatic change helped the enlargement of spring maize cultivation in China, but the water condition in some areas of this country might limit this enlargement.

Effects of fertilization and mowing on community biomass compensation in eastern alpine meadow of Tibetan Plateau.

YANG Zhong-ling, ZHANG Jia-yang, CHU Li-li, LI Hui**, XIAO Rui

2012, 31(09):  2276-2282. 

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A comparative study was made on the community biomass, species richness, and compensation index in eastern alpine meadow of Tibetan Plateau under four levels of fertilization and seven levels of mowing, aimed to understand the responses of the community to different intensities of fertilization and mowing. Fertilization increased the aboveground biomass and reduced the species richness, while mowing increased the species richness but had little effects on the aboveground biomass. With increasing fertilization, the dominance of Cyperaceae and forb species gradually shifted to grass species. Fertilization also promoted the community compensation ability, but the ability after mowing differed along the fertilization gradient. In addition, the probability of overcompensation increased with increasing mowing intensity and decreasing mowing number along the fertilization gradient. Therefore, fertilization was the main factor for community compensation, and the mowing effect on the community characters depended on fertilization level.

Nitrogen availability in black soils and its relations with crop yields under long-term applications of organic amendments.

SHI Hong-ai1,2, YOU Meng-yang2, LI Lu-jun2, HAN Xiao-zeng1,2**

2012, 31(09):  2283-2288. 

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Based on a long-term field experiment, this paper studied the effects of longterm applications of organic amendments (straw and organic manure) on the nitrogen availability in black soils of Northeast China, and analyzed the relationships between the soil nitrogen supply and the crop biomass and yield. The applications of chemical fertilizer plus organic manure and of chemical fertilizer plus low amounts of straw increased the soil inorganic nitrogen and nitrate nitrogen significantly, and thereby, promoted the crop yields. The application of chemical fertilizer plus high amounts of straw increased the soil nitrogen mineralization rate, but the soil inorganic nitrogen content had less increase, as compared with the application of chemical fertilizer plus low amounts of straw, possibly due to the enhanced soil nitrogen transformation or nitrogen losses such as nitrate nitrogen leaching under high level of straw application. Our study suggested that it would be of importance to apply rational amount of organic amendments to improve the nitrogen availability in black soils, increase the crop yields, and protect the environment.

Effects of conservation tillage on soil photosynthetic bacteria and type II methanotrophs.

WANG Jing-jing1,2, LI Xin-yu1, XU Ming-kai1, SU Zhen-cheng1, LI Xu1, SUN Jian1, ZHANG Hui-wen1**

2012, 31(09):  2289-2298. 

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Conservation tillage has beneficial effects on soil microbes, but the effects on soil photosynthetic bacteria and methanotrophs are rarely reported. In this study, denaturing gel gradient electrophoresis (DGGE) and quantitative PCR technique were adopted to investigate the abundance and community structure of photosynthetic bacteria and type Ⅱ methanotrophs in a fluvoaquic soil as affected by different tillage modes (no-tillage and conventional tillage) and straw mulching (0, 50%, 100%). Under no tillage, the diversity of soil photosynthetic bacteria was significantly higher but the abundance was slightly lower, as compared with those under conventional tillage, and there was a significant positive correlation between the diversity of soil photosynthetic bacteria and the soil total nitrogen. Both the abundance and the diversity of soil photosynthetic bacteria had a trend of increased with increasing amount of straw mulch. Tillage, straw mulching, and their interaction also had definite beneficial effects on the abundance and diversity of type Ⅱ methanotrophs. In all treatments, the community structure of soil photosynthetic bacteria and type Ⅱ methanotrophs had less change. The dominant groups of soil photosynthetic bacteria were Rhizobiales and Sphingomonadales, and that of type Ⅱ methanotrophs was Methylocystaceae.

Effects of atmospheric and soil lead on lead accumulation in maize plants and its contribution to maize seed.

ZHOU Ying, LI Guo-chen, ZHANG hong, WANG Yan-Hong**, CUI Jie-hua, WANG Shi-cheng

2012, 31(09):  2299-2304. 

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By foliar spraying Pb to simulate atmospheric Pb and by adding Pb into soil to simulate soil Pb, this paper studied the accumulation and allocation of atmospheric and soil Pb in maize plants, the relationship between leaf and seed Pb contents, and the contribution rates of atmospheric and soil Pb to seed Pb. After foliar spraying Pb, the Pb concentration in maize organs was in the order of leaf > stalk, root > seed, mainly allocated in leaf; after adding Pb into soil, the Pb concentration in maize organs was in the order of root > stalk > leaf > seed, mainly allocated in root. With the increase of atmospheric and soil Pb concentration, the Pb concentration in the organs increased to different extents. There was a significant positive correlation between the seed Pb concentration and the Pb concentrations in soil and leaf (P<0.01). The toxicity threshold value of Pb added in soil was 118.95 mg·kg^-1. The contribution rates of atmosphere and soil Pb to seed Pb were 53.7% and 46.3%, respectively, suggesting that foliar transfer of atmospheric Pb was the dominant pathway for the Pb intake of maize seeds.

Removal efficiency and uptake kinetics of nitrogen in water body by Salix integra.

WANG Ying, ZHANG Jian-feng**, CHEN Guang-cai

2012, 31(09):  2305-2311. 

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A water culture experiment was conducted to study the uptake of nitrogen (N) in simulated eutrophic water by 2 Salix integra clones (‘Yizhibi’ and ‘Weishanhu’), and the routine depletion technique was adopted to approach the uptake kinetics of NH₄⁺-N and NO₃^--N by the root systems of these two clones. In low concentrations of eutrophic water, the 2 clones could effectively remove N, with the removal rate of total N being >90%, which was 2 times as that in high concentrations of eutrophic water. The 2 clones could also effectively remove phosphorous (P), with the removal rate of total P reached 80% and 92% in the low and high concentrations of eutrophic water, respectively. Compared with ‘Weishanhu’, ‘Yizhibi’ had a higher efficiency in removing total N and total P, and the 2 clones performed better in higher concentrations of the simulated eutrophic water. Under the conditions of only existing NH₄⁺-N or NO₃^--N, ‘Weishanhu’ had greater maximum N uptake rate and N affinity than ‘Yizhibi’; when the other N sources existed, the NH₄⁺-N or NO₃^--N uptake rate of the two clones fell down to 50%. It was concluded that these 2 clones performed well in the ecological remediation of eutrophic water, and could be chosen as the better tree species for non-point source pollution control.

Chemical components of aquatic plants applied in ecological restoration of eutrophic water in Lake Hongfeng, Guizhou Province of Southwest China.

WANG Jing-fu1,2, CHEN Jing-an1**, PU Pei-min3, LI Jian1, YANG Yong-qiong1,2, YANG Hai-quan1,2

2012, 31(09):  2312-2318. 

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The deep lakes in Plateau Canyon, because of their deep water and their dramatic water level change, are not conducive to the growth of aquatic plants, and thus, the ecological restoration techniques used for shallow lakes are difficult to be applied in deep lakes. In this study, various kinds of aquatic plants were planted on the floating island carrier in Youer Bay at the Lake Hongfeng, a typical plateau deep lake in Guizhou, and the chemical components (nitrogen, phosphorus, and heavy metals) in the roots, stems, and leaves of the plants were analyzed. The nitrogen content of the plants was Potamogeton crispus > Rumex > Silpniumper foliatum, the phosphorous content was P. crispus > Elodea muttallii > Rumex, and the effective plants for both nitrogen and phosphorus removal were P. crispus, E. muttallii, and Rumex. All test aquatic plants could accumulate the heavy metals Cu, Cd, Pb, Zn, and Hg. The cumulative concentration of the heavy metals in the plants was in the order of Zn > Pb > Cu >> Cd > Hg. In different parts of the plants, root had a higher bioaccumulation coefficient than stem and leaf. The Zn/Cd ratio was higher in leaves than in stems and roots. Overall, Lolium perenne, Rumex, and P. crispus had greater potential application prospect in water phytoremediation. There was a significant positive correlation between plant total nitrogen (TN) and total phosphorus (TP), but no obvious correlation between plant nutrients and heavy metals. The plant heavy metals were significantly positively correlated with each other. This study also showed that terrestrial plants could grow well on the floating island barrier, being available in the ecological remediation of the polluted water in deep lakes. In practice, both the water pollution and the plant absorption characteristics should be considered in selecting the best plant combinations.  

Effects of nitrification inhibitors on N₂O emission from different upland agricultural soils.

BAI Xue1,2, XIA Zong-wei1, GUO Yan-ling1, ZHANG Ying1, XU Hui1**, WANG Zhen-yu1

2012, 31(09):  2319-2329. 

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A laboratory incubation experiment was conducted to evaluate the effects of nitrification inhibitors dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) applied with urea fertilizer on the N₂O emission, nitrogen transformation rate, and microbial community structure in meadow brown soil (Shenyang, Northeast China), cinnamon soil (Yuncheng, Central China), and silt loam soil (Minnesota, USA). In meadow brown soil, both of the two nitrification inhibitors reduced the N₂O emission by 54.1%-75.9%, but had no effects on soil mineral nitrogen content. The DCD inhibited the nitrification potential of meadow brown soil by about 24%, while the DMPP was inefficient under the higher soil moisture content. In cinnamon soil, the DMPP had significant inhibitory effect on the N₂O emission and nitrification potential, with the N₂O emission decreased by 85.5% and 66.7% and the nitrification potential reduced by 97.2% and 96.4% under lower and higher soil moisture contents, respectively. The DCD in cinnamon soil showed a weak inhibitory effect on the N₂O emission (decreased by 24.6%-57.5%) under lower soil moisture content, and no effect under the higher soil moisture content. The DMPP in silt loam soil decreased the N₂O emission by 42.9% and 53.1% under lower and higher soil moisture contents, respectively, while the DCD was inefficient under higher soil moisture content. In meadow brown soil and cinnamon soil, applying urea fertilizer alone promoted the growth and reproduction of soil ammoniaoxidizing bacteria (AOB) effectively, while the application of DCD and DMPP decreased the abundance of AOB by 4.1%-63.5% but had little effects on the abundance of soil ammoniaoxidizing archaea (AOA) and denitrifying bacteria. As compared with AOB, AOA were dominant in meadow brown soil and cinnamon soil, but the abundance of AOB amoA had a significant positive correlation with soil nitrification potential, indicating that soil AOB played more important role in the nitrification of these two soils.

Reactive oxygen production and genome DNA polymorphism change in root tip tissues of two leguminous species with different tolerance under Cd stress.

ZHANG Fen-qin1, ZHANG Hong-xiao2, SHEN Zhen-guo3**

2012, 31(09):  2330-2336. 

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The effects of cadmium (Cd) on the reactive oxygen productions and genome DNA polymorphism changes in roots of Phaseolus aureus Roxb. cv. VC3762 (Cdsensitive species) and Vicia sativa L. cv. 333/A (Cdresistant species) seedlings were investigated using hydroponic solution culture. The results showed that Cd stress decreased the genomic template stability and induced the changes of the genome DNA polymorphism in the root tips of the two species, manifesting the variation of band intensity, loss of normal bands, and appearance of new bands. Meanwhile, Cd stress inhibited the root growth and increased the production of O₂^-· and the accumulation of H₂O₂ in the roots. The root length of the two species under Cd stress was negatively correlated with the production of O₂^-·, accumulation of H₂O₂, and genome DNA polymorphism in root tip tissues, and the genome DNA polymorphism was positively correlated with the accumulation of H₂O₂ under Cd stress.

Cadmium-induced DNA damage of arabidopsis seedlings.

SUN Li-zong1,2, LIU Wan1, MA Shan-shan1,2, QIN Qin1,2, TAI Pei-dong1, LI Pei-jun1

2012, 31(09):  2337-2343. 

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By using random amplified polymorphic DNA (RAPD) technique in combining with morphological and physiological observation, this paper studied the genomic DNA damage of Arabidopsis thaliana seedlings under the Ca stress. After treated with 0.25, 30 and 5.0 mg·L^-1 of Cd for 24 days, the root elongation growth of the seedlings was inhibited, the total soluble protein content in shoots decreased after an initial increase, but the leaf number, fresh weight, and chlorophyll content were less affected. Using 12 oligonucleotide primers (10 bp) to amplify the genomic DNA of the seedlings shoot and root cells by polymerase chain reaction (PCR), it was observed that the RAPD profiles showed obvious differences between the normal and Cdexposed plantlets, and the change effect was dosedependent. The genomic template stability (GTS) decreased with increasing Cd stress. The GTS of the shoots in the treatments  0.25, 3.0 and 5.0 mg·L^-1 of Cd was 91%, 89%, and 80%, and that of the roots was 71%, 67%, and 60%, respectively. In sum, the changes in the DNA polymorphism of A. thaliana seedlings detected by RAPD technique could be used as a biomarker to detect the genotoxic effect of Cd on plants, and the changes in the RAPD profiles of A.thaliana roots were more sensitive than the other indicators, being more suitable for the diagnosis of soil pollutants.

Geographical components of macrofungal flora in Huangpushan Nature Reserve, Anhui Province of East China.

CHAI Xin-yi**, ZHU Shuang-jie, YIN Pei-feng, XIANG Yu-yong

2012, 31(09):  2344-2349. 

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To understand the diversity of macrofungal flora in Huangpushan Nature Reserve of Anhui Province, an investigation was conducted on the geographical components of the flora. A total of 103 macrofungal species were identified, belonging to 48 genera of 24 families. The dominant families were Tricholomataceae (14 species, 13.59%), Russulaceae (11 species, 10.68%), Cortinariaceae (10 species, 9.71%), and Polyporaceae (10 species, 9.71%), and the dominant genera were Lactarius (8 species, 7.77%), Psathyrella (6 species, 5.83%), Cortinarius (5 species, 4.85%), and Marasmius (5 species, 4.85%). Geographically, the genera could be divided into four components, i.e., cosmopolitan (58.33%), pantropical (29.17%), north temperate (10.42%), and tropical or subtropical (2.08%), and the species could be grouped into four components, i.e., cosmopolitan (45 species, 43.69%), tropical or subtropical (31 species, 30.1%), temperate (24 species, 23.3%), and Eurasia North America Australia (3 species, 2.91%). It was suggested that the geographical components of macrofungal flora in Huangpushan Nature Reserve were largely cosmopolitan, followed by tropical or subtropical and by north temperate.

Seasonal changes of macroalgae community structure in intertidal zone of Shengsi Archipelago, East China.

LIN Qing-jing, JIANG Xia-min**, XU Zhen, TANG Feng, WANG Tao

2012, 31(09):  2350-2355. 

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From August 2010 to August 2011, an investigation was conducted on the macroalgae in the intertidal zone of Shengsi Archipelago. A total of 114 macroalgae species belonging to 53 genera of 3 phyla were identified, among which, 75 species of 33 genera belonged to Rhodophyta, 21 species of 13 genera belonged to Phaeophyta, and 18 species of 7 genera belonged to Chlorophyta. Rhodophyta, Phaeophyta, and Chlorophyta accounted for 65.8%, 18.4%, and 15.8% of the total, respectively. The macroalgae had the largest number (87 species) in Gouqi Island, followed by in Jinping Island (42 species), and in Maguan Island (26 species). 79.8% of the macroalgae were distributed in low intertidal zone, and 62.3% distributed in middle intertidal zone. The similarity value of the algae composition between the low and middle intertidal zone, the middle and high intertidal zone, and the low and high intertidal zone was 0.57, 0.15, and 0.06, respectively. The species number of macroalgae changed with season and in the order of summer (57 species) > winter (55 species) > spring (52 species) > autumn (46 species). The dominant species also differed with season. The dominant species in spring were Undaria pinnatifida, Ulva pertusa, Ulva linza, and Pachymenia carnosa, those in summer were Sargassum vachellianum,Chondria crassicaulis,Sargassum thunbergii and Alga eucheumae, those in autumn were Gracilaria verrucosa, Gigartina intermedia suring, Sargassum thunbergii, and Ulva lactuca, and the dominant species in winter were Scytosiphon lomentarius, Porphra suborbiculate, Sargassum thunbergii, and Polysiphonia japonica.

Macrozoobenthos community structure and water quality evaluation of Yuqiao Reservoir in Tianjin, North China.

MA Xiu-juan1, SHEN Jian-zhong1**, SUN Jin-hui2, WANG Hai-sheng1, ZHANG Kai3

2012, 31(09):  2356-2364. 

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A quarterly investigation of the macrozoobenthos community in Yuqiao Reservoir was conducted during May 2010 to May 2011. A total of 51 macrozoobenthos species were found, among which, Insecta (23 species), Mollusca (15 species), Oligochaeta (12 species), and others (1 species) accounted for 45.1%, 29.4%, 23.5%, and 2.0% of the total, respectively. The dominant species were Glyptotendipes lobiferus, Cipangopaludina cathayensis, Limnodrilus hoffmeisteri, and L. claparedeianus.The average annual density and biomass of macrozoobenthos were 159.58 ind·m^-2 and 3.31 g·m^-2, respectively. The macrozoobenthos had the highest density in spring, followed by in winter and autumn, and in summer, and had the highest biomass in winter, followed by in summer and spring, and in autumn. The evaluation with Goodnight biotic index (GBI), ShannonWiener diversity index (H′), Margalef richness index (d), biological pollution index (BPI), familylevel biotic index (FBI), and integrated pollution index (BI) indicated that the overall water quality of the Reservoir was in slightmoderate pollution (Ⅱ-Ⅲ). As compared to that in 1999-2000 (Ⅲ), the water quality of Yuqiao Reservoir was somewhat improved.

Influence of different bird-driving modes on the behaviors of orchard pest birds.

HU Can-shi1, LI Hai-yang1, YE Yuan-xing1, CHEN Li-xia1, ZHANG Xiao1, ZHAO Xin-ru2, WU Wen-biao3, DING Chang-qing1**

2012, 31(09):  2365-2370. 

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Playing back bird calls is an effective and noninvasive way to drive pest birds away from farms and orchards, and widely used in agriculture and fruit industry. However, little attention has been paid to assess the bird-driving effect of playing back bird calls and the bird response behaviors. In order to evaluate the effect of playing back bird calls on driving orchard pest birds, three bird-driving modes with playing back Accipiter gentilis calls, Pica pica scared calls, and Cyanopica cyana scared calls were set up in two cherry orchards in Haidian District of Beijing in May 2009, and an indoor experiment was conducted from April to May, 2010 to examine the behavioral responses of the individuals of two main pest birds P. pica and C. cyana. The playback of A. gentilis calls could significantly reduce the population of P. pica in the cherry orchards (P<0.05), and scare the C. cyana and Passer montanus. The pest birds had different behaviors to respond different bird-driving modes, and thus, it would be necessary to adopt comprehensive techniques and measure cost-profit efficiency, and to establish effective assessment mechanism in pest bird control management.

Effects of tillage mode on the diversity of soil meso- and micro-fauna.

ZHAN Li-li1,2, XU Yan-li1**, ZHANG Xing-yi1, PAN Feng-juan1, PEI Xi-chao3, LIU Zhen-yu4

2012, 31(09):  2371-2377. 

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To understand the effects of tillage mode on the community structure and diversity of soil meso- and micro-fauna, a field experiment was conducted at the National Observation Station of Agroecology System in Hailun of Northeast China. Five tillage modes including no tillage, reduced tillage, mold board tillage, combined tillage, and rotary tillage were chosen, and the modified Tullgren method were adopted to extract soil fauna from 0-15 cm soil layer, with the community structure and vertical distribution of soil meso- and micro-fauna analyzed. There existed differences in the community structure and vertical distribution of soil meso- and micro-fauna under different tillage modes. Liodidae and Oribatellidae were the dominant families under the five tillage modes, and the similarities of the community structure of soil meso- and micro-fauna were higher between moldboard plough and rotary tillage and between no tillage and reduced tillage. Combined tillage kept the surface accumulation of soil fauna. The diversity, evenness, and dominance of the soil fauna under reduced tillage were higher than those under other tillage modes. It was suggested that tillage mode could affect the community structure of soil meso- and micro-fauna, and conservation tillage (combined tillage and reduced tillage) could benefit the stability of soil faunal community structure and kept the surface accumulation of soil fauna in vertical distribution.

Community structure and temporal dynamics of arthropod in upper canopy of wheat field: A study with suction trap.

JIANG Yue-li1, WU Yu-qing1**, QIAO Ge-xia2, DUAN Yun1, MIAO Jin1

2012, 31(09):  2378-2384. 

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In this study, suction trap was first applied for the survey and diversity analysis of arthropod community in an agroecosystem in China. A suction trap was installed in a winter wheat field in Yuanyang County of Henan Province to collect arthropods during the period from April 7 to June 2, 2010. A high species richness of the arthropod community was observed in the upper canopy of winter wheat, with 64 species from 8 orders and 39 families trapped. Diptera and Hemiptera were most dominant, followed by Coleoptera and Hymenoptera. The most dominant species were Sitobion miscanthi and Rhopalosiphum padi. The Cecidomyiidae and Chironomidae of Diptera and the Aphidiidae of Hymenoptera were also dominant. Based on the analysis of arthropod diversity, the species richness, total quantity, and diversity indices varied through time, mainly with an increasing trend, but the uniformity had less obvious variation. The occurrence of the main insect pests and natural enemies peaked after May 1, and the prevalent period of Aphidiidae was 10-20 days later than that of wheat aphids.

Butterfly diversity in Yinpingshan Nature Reserve of Dongguan, South China.

LI Zhi-gang1, ZENG Huan-chen2, YE Jing-wen1, DAI Jian-qing1, HAN Shi-chou1**

2012, 31(09):  2385-2390. 

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A fourtime investigation with line transect method was conducted on the butterfly diversity in Yinpingshan Nature Reserve of Dongguan in 2010-2011. Fortytwo species of butterfly belonging to 31 genera and 9 families were identified. Pieridae had the most abundant individuals, followed by Papilionidae, Nymphalidae, and Satyridae. Nymphalidae was the highest in species richness, followed by Papilionidae, and Pieridae. The Shannon index and abundance of the butterfly were the highest in July, followed by in May,  November, and February. Due to the rapid social and economic development, the Yinpingshan Nature Reserve suffered great environmental stress, leading to the significantly lower species richness and abundance of butterfly than that in the peripheral areas of the Pearl River Delta. It was suggested that more attention should be taken to restore and improve the environmental quality during the process of urban development, so that the biodiversity could be effectively protected.

Effects of land use change on soil conservation value in southern Loess Plateau of Northwest China.

BIAN Hong-yan**, PANG Jiang-li, REN Zhi-yuan, XU Qian

2012, 31(09):  2391-2396. 

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Soil conservation capability is closely related to land use/cover change (LUCC). Based on 3S technology and by using Markov matrix, US universal soil loss equation (USLE), contingent valuation method, shadow project method, and opportunity cost method, this paper analyzed the characteristics of LUCC in southern Loess Plateau from 1980 to 2005, and quantitatively estimated the soil conservation capability and its ecological benefits under different land use types. In the study area, cultivated land and construction land changed significantly from 1980 to 2005. During this period, 1123.80 km² cultivated land in this area was converted to construction land, and the total soil conservation capability was declined from 20.43×10.8 t in 1980 to 19.94×10.8 t in 2005. The soil conservation capability per unit area of different land use types was in the order of construction land < cultivated land < unutilized land < grassland < forestland. In 1980 and 2005, the total soil conservation value in the study area was 674.27 billion Yuan and 1064.80 billion Yuan, respectively, and forestland, grassland, and cultivated land played leading roles in the soil conservation.

Major terminologies and concepts in seed dispersal biology.

ZHU Jin-lei1,2, LIU Zhi-min1**

2012, 31(09):  2397-2403. 

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Seed dispersal is a research hotspot nowadays in evolutionary biology, conservation biology, and restoration biology, with a rapid development over the last two decades in the world. However, little related research has been reported in China, and many terminologies and concepts in seed dispersal biology are hard understandable to relevant Chinese researchers. This paper collected the major terminologies and concepts in seed dispersal biology, aimed to contribute to constructing the framework of terminologies and concepts in seed dispersal biology and to hastening the seed dispersal research in China.

DNA damage and DNA mismatch repair of plants under adverse circumstance stress: A review.

ZHONG Ming1, CHEN Zhuo1,3, LIU Wan2**, LI Pei-jun2, TAI Pei-dong2

2012, 31(09):  2404-2411. 

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The genomic DNAs in plants are quite stable in normal circumstances, but easily to be damaged under adverse circumstance stresses such as chemical mutagens, ultraviolet ray, ionizing radiation, and fungal and bacteria toxins, as well as the reactive oxygen free radicals generated in plant metabolic processes. The main DNA lesions are the altered bases, apurinic/apyrimidinic (AP) sites, mismatch base, deletion or insertion, linked pyrimidines, DNA adducts, DNA strand breaks, methylated damage, and intra and interstrand crosslinks. These DNA lesions could be genotoxic or cytotoxic to plant cells, while the repair of the DNA lesions is the basis of the plant antagonism to all kinds of damage. This paper summarized the research progress on the DNA damage (methylated damage, and DNA adducts) and DNA mismatch repair (procaryotic organism MMR, botanic MMR, and microsatellite instability) of plants. It was considered that in the bioremediation of environmental contaminants and in the early diagnosis and assessment of environmental pollution, plant DNA mismatch repair genes and MMR mutants would have higher application prospective.

Interspecific differences of seagrass morphology and growth patterns and their allometry.

ZHENG Feng-ying, HAN Xiao-di, JIN Yan-mei, ZHANG Wei, ZHAO Hong**

2012, 31(09):  2412-2419. 

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Seagrass is a kind of marine submersed higher plants, and belongs to typical rhizomatousclonal plants. Rhizome diameter and ramet weight are the first and the second useful descriptors of seagrass size, respectively, while body size is a key identification feature for seegrasses. In this paper, a comprehensive analysis was made on the 6 module indices and 18 growth indices of seagrass. The results indicated that fruit size, leaf size, and shoot weight were speciesspecific. Shoot plastochrone, branching rate of horizontal rhizome, leaf production per year, shoot longevity, and branching rate of vertical rhizome were the most speciesspecific dynamic properties, suggesting that the difference in seagrasses growth dynamics was mainly reflected in the clonal growth capacity and ramet life cycle length. Large seagrasses displayed a phalanx clonal architecture, while small seagrasses except Cymodocea nodosa displayed a guerrilla growth strategy. The horizontal spreading rate of large seagrasses genets was slower than that of small ones. There existed allometric relationships between segrasses size and their architectural properties and dynamic properties. With increasing seagrass size, the plastochrone interval and longevity of leaf, ramet, and node extended in modular growth level, and the horizontal internodal length and elongation rate of horizontal rhizome, ramet production rate, branching rate, and branching angle decreased while spacer increased in clonal growth level. The physiological integration among clonal fragments enhanced with the increasing size. For the seagrass populations, the biomass increased while the density decreased when the seagrass size increased. Therefore, seagrass size strongly affected the architecture module, growth type, clonal architecture, population density, and productivity of seagrasses. The differences in form, growth dynamics, and module component showed the differences of seagrasses in their life strategy and ecological functions, which could be the useful information in exploring the restoration theory of seagrass bed.

Effects of Bttransgenic crops on soil earthworms: A review.

ZHANG Yan-yan1,2,3, SHU Ying-hua1,2,3, WANG Jian-wu1,2,3**

2012, 31(09):  2420-2424. 

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Whether the commercial planting of Bacillus thuringiensis (Bt) transgenic crops could have potential adverse effects on soil ecosystem is a controversial issue over the past decade. The Bt larvicidal protein from Bttransgenic crops can enter into the soil in various ways, leading to the changes in soil organisms and in the essential functions of soil ecosystem. Soil earthworm can accelerate the degradation of animal and crop residues, and promote the decomposition and mineralization of soil organic matter. As compared with other soil organisms, soil earthworm is more sensitive to some pollutants. In the present paper, the research progress in the effects of Bttransgenic crops on the nontarget soil animal earthworm was summarized from the aspects of the earthworm species and the methods applied in related experiments as well as the problems explored in related studies, and the future research trend was prospected. The aim of this review was to provide a reference for the study of the effects of Bttransgenic crops on nontarget soil animals, and to offer the basis for the comprehensive evaluation of Bttransgenic crops on soil ecosystem.

Ecological remediation technologies for China’s freshwater aquaculture pond environment: A review.

SONG Chao, CHEN Jia-zhang, QIU Li-ping, MENG Shun-long, FAN Li-min, HU Geng-dong**

2012, 31(09):  2425-2430. 

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Traditional freshwater aquaculture is facing more and more serious environmental problems, and thus, ecological remediation technologies for freshwater pond environment are more attracted. The insitu remediation represented by fish-vegetable mutualism mode (FVMM) and the ectopic remediation represented by recirculating aquaculture system (RAS) are the emphases of present researches. From the viewpoint of water eutrophication, and with pond nitrogen cycle as the point of penetration, this paper analyzed the advantages and disadvantages of FVMM and RAS, and discussed their referred area configuration. The FVMM could reduce the discharge coefficient of fish pond, but the ecological balance would be hard to realize if this mode was applied to all our fish ponds. The RAS could not avoid the extra economic cost and land resources, but its zerodischarge made this system have definite ecological value when applied in eutrophication area.

Simulation model of spring maize developmental stages in Northeast China based on climatic suitability.

HOU Ying-yu**, WANG Liang-yu, MAO Liu-xi, Lu Hou-quan, WANG Jian-lin

2012, 31(09):  2431-2436. 

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Based on the ecophysiological development processes of spring maize and the principle of the physiological development time for specific type of crops at a given development stage being a constant, a simulation model for spring maize developmental stages was established by the scale of physiological development time. In the published methods for determining crop physiological development time, only the daily thermal and photo-periodical effectiveness is considered, and some specific genetic parameters are introduced to adjust the genotypic differences. However, it is difficult to gain these parameters in real time in large regional scale when simulation model comes into use operationally. In this paper, the physiological development time during the development stages of spring maize was determined based on the climatic suitability, with the joint effects of sunlight, air temperature, and precipitation on the crop development processes considered. The validation of the model with the data from the agro-meteorological observation stations in Northeast China in 2009 and 2010 indicated that there was a high goodness of fit between the simulated results and the observed values. The correlation coefficient between the simulated results and observed values was over 0.84 in vegetative growth stage and over 0.77 in reproductive growth stage. Moreover, the root mean square error (RMSE) between the simulated results and the observed values during the whole crop growth period was 3.8 days. Therefore, this model was relatively robust on mechanistic explanation, had high operability, and could be applied to simulate and predict the date and duration of different growth stages of maize in agrometeorological information service.

Conformity degree evaluation of urban ecological river: A case study in Shanghai.

ZUO Zhuo**, ZHU Xue-dan, HU Wei, ZHANG Lu-jun

2012, 31(09):  2437-2442. 

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Urban river ecosystem is composed of two subsystems, i.e., river water and riparian area, and provides many resources and eco-services to human society. In China, the ecological construction and management of urban river is still at the beginning, and it is of great importance to exactly define ecological river and establish relevant evaluation index system. This paper expatiated on the characteristics of urban ecological river, and, based on the features of ecological construction of urban rivers in China, established an evaluation system containing 5 primary indices and 23 secondary indices, and first put forward the urban river ecological conformity index (URECI). Taking Shanghai as a case, 9 urban rivers were analyzed to evaluate their ecological conformity degree. The 9 urban rivers had a URECI of 5.60-17.25, among which, the Xinjiangwan Town River Network had the outstanding level of ecological conformity, the Zhengyicun River, Dianpu River, Dayucun River, and Xinglonggang River had the satisfactory level, and the others were in ordinary level.