Table of Content

20 March 2010, Volume 21 Issue 3

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Articles

Spatial relevance between natural regeneration of Picea and heterogeneity of soil available nitrogen in Guandi Mountain

2010, 21(3):  533-540. 

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By using geostatistic and pattern analysis methods, this paper studied the spatial pattern of Picea seedlings in naturally regenerated conifer (Picea) and mixed (Picea-Populus-Betula) forests in Guandi Mountain of Shanxi Province, China. The spatial distribution of soil nitrogen was also quantified by semivariogram analysis. To understand the effects of spatial heterogeneity of soil nitrogen on the regeneration of Picea seedlings, the relationships between the regeneration pattern of the seedlings and the spatial distribution of soil nitrogen were investigated by using GIS superposition and statistical analysis. In conifer stands, the distribution of Picea seedlings appeared as a patch pattern and was auto-correlated; while in mixed stands, the distribution was of gathering distribution pattern controlled by random factors. In the Picea stands with relatively low soil nitrogen content, the spatial distribution of soil available nitrogen was significantly heterogeneous and auto-correlated; whereas in the mixed stands with high nitrogen content, the distribution of soil available nitrogen showed random heterogeneity. In the conifer stands, the spatial correlation between Picea seedlings regeneration pattern and soil available nitrogen distribution was significant, regenerating more seedlings in the patches with higher NH₄⁺-N concentration; while in the mixed stands, the correlation was not significant.

Short term effects of low intensity thinning simulated by gap on ground microclimate and soil nutrients of pure spruce plantation.

2010, 21(3):  541-548. 

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Taking a dense spruce pure plantation as test object and simulating the formation of natural forest gap, this paper studied the effects of low intensity thinning by gap creation on the ground temperature, ground humidity, and nutrient contents in different soil layers of the plantation. In the first year of gap creation, the mean diurnal temperature in the gap across the growth season (May-September) increased, while the mean diurnal humidity decreased. The soil organic matter (SOM) and NH₄⁺-N contents in O-horizon (humus layer) increased by 19.62% and 283.85%, and the dissolved organic carbon (DOC) and NO₃^--N contents decreased by 77.86% and 23.60%, respectively. The SOM, total nitrogen (TN), and NO₃^--N contents in 0-10 cm soil layer increased by 45.77%, 37.14%, and 75.11%, and the  NH₄⁺-N, DOC, and total phosphorus (TP) contents decreased by 48.56%, 33.33%, and 13.11%, respectively. All the results suggested that low intensity thinning by gap creation could rapidly improve the ground microclimate of the plantation, and consequently, promote the soil microbial activity and mineralization processes in O-horizon, the release of soil nutrients, and the restoration of soil fertility.

Multiple time scale analysis of precipitation series in Changbai Mountain Region in 1959-2006.

2010, 21(3):  549-556. 

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Based on the 1959-2006 monthly and annual precipitation data from Songjiang, Donggang, Changbai, Helong, Linjiang, and Tianchi meteorological stations, and by using Morlet wavelet method, a multiple time scale analysis was made on the precipitation series from May to September (vegetation growth season), November to next April (snow season), and the annual in Changbai Mountain Region. The precipitation series was decomposed and low-frequency reconstructed at different levels by using the db5 wavelet of Daubechies wavelets, and the trend of the reconstructed series was identified and analyzed. In 1959-2006, there existed 3-6 years, 10-13 years, and 24-30 years cycles of precipitation series in vegetation growth season, 1-2 years, 5-7 years, and 17-20 years cycles in snow season, and 8-10 years, 16-20 years, and 25-30 years cycles in the annual, and the annual precipitation series showed an overall downward trend.

Effects of elevated CO₂ and O₃ on active oxygen metabolism of Quercus mongolica leaves.

2010, 21(3):  557-562. 

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By using open top chamber fumigation method, this paper studied the effects of elevated O₃ (≈80 nmol·mol^-1) and CO₂ (≈700 μmol·mol^-1), single and in combination, on the active oxygen metabolism of Quercus mongolica leaves. Elevated O₃ increased the superoxide anion radical (O₂^•) generation rate, hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) contents, and electrolyte leakage (EL) (P<0.05), but decreased the superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) activities and ascorbate (AsA) content (P<0.05); while elevated CO₂ had no significant effects on the active oxygen metabolism of Q. mongolica leaves. The combination of elevated O₃ and CO₂ had less effects on the O₂^• generation rate, H₂O₂ and MDA contents, and EL, indicating that elevated CO₂ alleviated the oxidative stress of elevated O₃ on Q. mongolica leaves, but increased the SOD, APX, and CAT activities and the AsA and total phenol contents, compared with elevated O₃ (P<0.05), indicating that elevated CO₂ alleviated the negative effects of elevated O₃ on Q. mongolica leaf antioxidant system.

Soil greenhouse gases emission from an Acacia crassicarpa plantation under effects of understory removal and Cassia alata addition.

2010, 21(3):  563-568. 

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Forest soil is one of the main sources of greenhouse gases CO₂, CH₄, and N₂O. By using static chamber and GS technique, this paper measured in situ the CO₂, CH₄, and N₂O fluxes of Acacia crassicarpa plantation in Heshan Hilly Land Interdisciplinary Experimental Station under Chinese Academy of Sciences (CAS), and studied the soil CO₂, CH₄ and N₂O emissions from the plantation under effects of understory removal and Cassia alata addition. The CO₂ flux of the plantation maintained at a higher level during rainy season but decreased obviously in dry season, while the CH₄ and N₂O fluxes varied widely from September to November, with the peaks in October. Under the effects of understory removal and C. alata addition, the soil in the plantation could be a sink or a source of CH_4, but consistently a source of CO₂ and N₂O. Understory removal enhanced the soil CO₂ emission (P<0.05), C. alata addition increased the soil CH₄ emission (P<0.05), while both understory removal and C. alata addition increased the soil N₂O emission (P<0.05). Surface soil temperature, moisture content, NO₃^--N concentration, and microbial biomass carbon were the main factors affecting the soil CO₂, CH₄ and N₂O emissions.

Effect of drought stress on photosynthetic characteristics and growth of Jatropha curcas seedlings under different nitrogen levels.

2010, 21(3):  569-576. 

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A pot experiment with controlled water supply was conducted to study the effects of drought stress (continuous drought for 0 d, 5 d, 10 d, …, 45 d) on the photosynthetic characteristics and growth of Jatropha curcas seedlings under different nitrogen fertilization levels(N₀, 0 kg N·hm^-2; N_L, 96 kg N·hm^-2; N_M, 288 kg N·hm^-2; N_H, 480 kg N·hm^-2). With the enhancement of drought stress, the leaf relative water content (RWC_l), height growth (Z_h), basal diameter growth (Z_d), leaf area (L_a), net photosynthetic rate (P_n), transpiration rate (T_r), and stomatal conductance (G_s) decreased significantly (P<0.01), irrespective of nitrogen fertilization level. The chlorophyll (Chl) content and water use efficiency (WUE) increased first and decreased then, while the intercellular CO₂ concentration (C_i) had an increase after an initial decrease. Under adequate water condition, nitrogen fertilization promoted the photosynthesis and growth of J. curcas seedlings to different degrees, and the effect was increased with increasing nitrogen fertilization level. Under drought stress, the effects of nitrogen nutrition on the photosynthesis and growth were dependent on drought intensity and nitrogen fertilization level. Specifically, increasing nitrogen fertilization level could promote the photosynthesis and growth of J. curcas seedlings under mild drought, the promotion effect of N_M was higher than that of N_L and N_Hunder moderate drought, and N_L had the best promotion effect while N_H weakened the effect or made it negative under severe drought.

Complex effects of simulated acid rain and Cu on the physiological characteristics of Paulownia fortunei and its detoxification mechanism.

2010, 21(3):  577-582. 

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A pot experiment was conducted to study the effects of simulated acid rain (pH 4.0, 5.0) and Cu (0-200 mg·kg^-1) on the physiological characteristics of Paulownia fortunei and its detoxification mechanism. With no Cu addition, the leaf chlorophyll, carotenoid, O₂^?, H₂O₂, and MDA contents of P. fortunei had no significant differences between the two acid rain treatments. However, with the addition of 100 and 200 mg Cu·kg^-1, the chlorophyll and carotenoid contents of treatment pH 4.0 were lower, while the O₂^?, H₂O₂ and MDA contents were higher than those of treatment pH 5.0. The chlorophyll a/b ratio of treatments Cu was higher than that of the control. The leaf Cu content decreased obviously with the increasing acidity of stimulated acid rain, but the root Cu content was in reverse. With increasing Cu addition, both the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) and the total contents of phytochelatins (PCs) and glutathione (GSH) in treatment pH 5.0 increased, while the activities of SOD, POD, CAT and APX in treatment pH 4.0 decreased after an initial increase, and the total contents of glutathione (GSH) decreased greatly in treatment 200 mg Cu·kg^-1. All of these demonstrated that the oxidative stress of high Cu concentration to P. fortunei was aggravated by stimulated acid rain.

Woody plant fine root biomass and its spatial distribution in top soil of broad-leaved Korean pine forest in Changbai Mountain

2010, 21(3):  583-589. 

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Geostatistic method was applied to study the spatial distribution of woody plant fine root biomass in a natural broad-leaved Korean pine (Pinus koraiensis）mixed forest soil in Changbai Mountain. The investigation was carried out in three selected plots, sized 50 m×50 m, in 2008. In the three plots, the living fine root biomass in surface soil (0-20 cm) was 3.195, 1.930, and 2.085 t·hm^-2, and the dead fine root biomass was 0.971, 0.581,and 0.790 t ·hm^-2, respectively. In 0-10 cm soil layer, the living fine root biomass had no correlation with the dead fine root biomass; but in 10-20 cm soil layer, a significant positive correlation was found between them (r=0.352，P<0.05). The variograms of living fine root biomass and dead fine root biomass could be well fitted by spherical model. Spatial variation explained more than 70% of the total variance of fine root biomass across three plots. The regressed ranges were 5.2, 14.6, and 9.8 m for living fine root biomass, and 4.3, 20.4, and 20.1 m for dead fine root biomass in plots 1, 2, and 3, respectively. For comparison, Bayesian method was also used to estimate the ranges for the fine root biomass. The results obtained by geostatistic method and Bayesian method were consistent with each other.

Effects of waterlogging on the growth and energy-metabolic enzyme activities of different tree species.

2010, 21(3):  590-596. 

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Aimed to understand the waterlogging tolerance and adaptation mechanisms of different tree species, a simulated field experiment was conducted to study the growth and energy-metabolic enzyme activities of one-year-old seedlings of Taxodium distichum, Carya illinoensis, and Sapium sebiferum. Three treatments were installed, i.e., CK, waterlogging, and flooding, with the treatment duration being 60 days. Under waterlogging and flooding, the relative growth of test tree species was in the order of T. distichum>C. illinoensis>S. sebiferum, indicating that T. distichum had the strongest tolerance against waterlogging and flooding, while S. sebiferum had the weakest one. Also under waterlogging and flooding, the root/crown ratio of the three tree species increased significantly, suggesting that more photosynthates were allocated in roots, and the lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH) activities of the tree species also had a significant increase. Among the test tree species, T. distichum had the lowest increment of LDH and ADH activities under waterlogging and flooding, but the increment could maintain at a higher level in the treatment duration, while for C. illinoensis and S. sebiferum , the increment was larger during the initial and medium period, but declined rapidly during the later period of treatment. The malate dehydrogenase (MDH), phosphohexose (HPI), and glucose-6-phosphate dehydrogenase (G6PDH)-6-phosphogluconate dehydrogenase (6PGDH) activities of the tree species under waterlogging and flooding had a significant decrease, and the decrement was the largest for T. distichum, being 35.6% for MDH, 21.0% for HPI, and 22.7% for G6PDH-6PGDH under flooding. It was suggested that under waterlogging and flooding, the tree species with strong waterlogging tolerance had a higher ability to maintain energy-metabolic balance, and thus, its growth could be maintained at a certain level.

Dynamics of sensible and latent heat fluxes over a temperate desert steppe ecosystem in Inner Mongolia.

2010, 21(3):  597-603. 

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This paper studied the diurnal and seasonal characteristics of sensible and latent heat fluxes over a temperate desert steppe ecosystem in Inner Mongolia, based on the 2008 observation data from eddy covariance tower. The diurnal patterns of sensible and latent heat fluxes over the ecosystem were both single kurtosis, with the maximum value being  319.01 W·m^-2 (on May 30th, 2008) and 425.37 W·m^-2 (on Jun 2nd, 2008), respectively, and occurred at about 12:00-13:30 (local time), which was similar to the diurnal pattern of net radiation but lagged about one hour of the maximum net radiation. The maximum diurnal variations of monthly mean sensible and latent heat fluxes occurred in May and June, and their minimum diurnal variations occurred in January and November, respectively. There was a closer relationship between soil moisture content and precipitation. Surface soil moisture content was most sensitive to precipitation, while the moisture content in deeper soil layers had a lagged response to precipitation. The seasonal dynamics of sensible and latent heat fluxes was similar to that of net radiation, and affected by precipitation. Sensible heat flux was obviously affected by net radiation, but latent heat flux was more sensitive to precipitation and mainly controlled by soil moisture content.

Spatial pattern of soil moisture at the cropland-grassland boundary in agro-pastoral transitional zone of North China.

2010, 21(3):  604-612. 

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By the methods of classic statistics and geostatistics, this paper analyzed the spatial heterogeneity of soil moisture at 0-50 cm depth in different sampling grain sizes (1 m×1 m and 2 m×2 m) at the cropland-grassland boundary in agro-pastoral transitional zone of North China. In study area, the soil moisture at 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, and 40-50 cm depths of cropland, grassland, and cropland-grassland boundary presented moderate variance, and the  coefficient of variation (CV) of grassland was highrr than that of cropland. The CV increased with soil depth, and a significant linear regression relation(P＜0.05) was observed between them in sampling grain size 1 m×1 m. In sampling grain size 1 m×1 m, the spatial heterogeneity of soil moisture at different depths was obviously higher at croplandgrassland boundary than in cropland and grassland, which had a moderate to strong spatial dependency, and the range (A₀) was 7.65-30.99 m; whereas in sampling grain size 2 m×2 m, the spatial distribution of soil moisture at cropland-grassland boundary had both the moderate to strong spatial dependency and the pure nugget effect, and the A₀ was 4.16-18.86 m, suggesting that there existed ecological edge effect of soil moisture at croplandgrassland boundary.

Carbon storage of poplar-crop ecosystem in Eastern Henan Plain.

2010, 21(3):  613-618. 

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Aimed to understand the carbon storage of poplar-crop ecosystem in Eastern Henan Plain, the poplar-crop ecosystems with different ages (5, 9, 11, and 13 years old) of poplar were selected, and each of them was further divided into four subsystems, i.e., forest, crop, litterfall, and soil. In the poplar-crop ecosystems with 5, 9, 11, and 13 years old poplar, the carbon storage of the subsystems forest and litterfall was summed as 7.86, 42.07, 44.31, and 60.71 t·hm^-2, respectively. Subsystem crop averagely sequestrated 6.8 t·hm^-2 of CO₂ per year, and the carbon storage of subsystem soil chieved 45.55, 51.06, 55.94, and 60.49 t·hm^-2, respectively. The total carbon storage of these four poplar-crop ecosystems reached 60.81, 100.09, 106.76, and 127.34 t·hm^-2, respectively, much higher than that in mono-cultured farmland (49.36 t·hm^-2). For the test poplar-crop ecosystems, the carbon storage of subsystems forest and soil occupied a large proportion, accounting for 87.1%-93.1% of the total carbon storage, while that of subsystems crop and litterfall occupied a relatively small proportion, being 6.9%-12.9% of the total, illustrating that agroforestry ecosystem had a high potential in carbon absorption and sequestration.

Effects of drought stress on leaf gas exchange and chlorophyll fluorescence of Salvia miltiorrhiza.

2010, 21(3):  619-623. 

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Taking the seedlings of Salvia miltiorrhiza cv. Sativa（SA) and S. miltiorrhiza cv. Silcestris（SI) as test materials, this paper studied the effects of drought stress on their leaf gas exchange and chlorophyll fluorescence parameters. After 15 days of drought stress, the net photosynthetic rate (P_n) and the maximal photochemical efficiency of PSⅡ (F_v/F_m) of SA were decreased by 66.42% and 10.98%, whereas those of SI were decreased by 29.32% and 5.47%, respectively, compared with the control, suggesting that drought stress had more obvious effects on the P_n and F_v/F_m of SA than of SI. For SI, the reduction of P_n under drought stress was mainly due to stomatal limitation; while for SA, it was mainly due to non-tomatal limitation. Drought led to a decrease of leaf stomatal conductance (G_s), but induced the increase of water use efficiency (WUE), non-hotochemical quenching coefficient (q_N), and the ratio of photorespiration rate to net photosynthetic rate (P_r/P_n), resulting in the enhancement of drought resistance. The increment of WUE, q_N, and P_r/P_n was larger for SI than for SA, indicating that SI had a higher drought resistance capacity than SA.

Comparison of spatial interpolation methods for daily meteorological elements.

2010, 21(3):  624-630. 

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A comparative study was made to evaluate the methods of inverse distance weighting (IDW), co-kriging (CK), and thin plate spline (TPS) in interpolating the average meteorological elements (including maximum air temperature, minimum air temperature, sunshine hours, and precipitation) of the 15^th day per month from the 1951-2005 comprehensive observation data of 559 meteorological stations in China. The results showed that the RMSEs for the maximum and minimum air temperature in a year interpolated by TPS were the smallest (1.02 ℃ and 1.12 ℃, respectively), and the R² between the observed and predicted values were the highest (0.9916 and 0.9913, respectively), compared with those interpolated by IDW and CK. In four seasons, the smallest RMSEs for the maximum and minimum air temperature interpolated by TPS were observed in autumn (0.83 ℃) and summer (0.86 ℃), respectively, and the R² between the observed and predicted values interpolated by TPS were higher in autumn than in other seasons. The RMSEs for the sunshine hours and precipitation in a year interpolated by TPS were the smallest (0.59 h and 1.01 mm, respectively),and the R² between the observed and predicted values were the highest (0.9118 and 0.8135, respectively), compared with those interpolated by IDW and CK. In four seasons, the RMSE for the sunshine hours in winter interpolated by TPS was the smallest (0.49 h), and the R² between the observed and predicted sunshine hours was the smallest (0.9293). The RMSE for the precipitation in winter interpolated by TPS was the smallest (0.33 mm), while the RMSE for the precipitation in summer interpolated by IDW was the smallest (2.01 mm). The R² between the observed and predicted precipitation in winter interpolated by CK was the highest (0.8781). It was suggested that TPS could be the optimal spatial interpolation method in interpolating and rasterizing the daily meteorological elements in China.

Spatial characteristics of soil organic carbon and nitrogen storages in Songnen Plain maize belt.

2010, 21(3):  631-639. 

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By using the data of 382 typical soil profiles from the second soil survey at national and county levels, and in combining with 1:500000 digital soil maps, a spatial database of soil profiles was established. Based on this, the one meter depth soil organic carbon and nitrogen storage in Songnen Plain maize belt of China was estimated, with the spatial characteristics of the soil organic carbon and nitrogen densities as well as the relationships between the soil organic carbon and nitrogen densities and the soil types and land use types analyzed. The soil organic carbon and nitrogen storage in the maize belt was （163.12±26.48）Tg and （9.53±1.75）Tg, respectively, mainly concentrated in meadow soil, chernozem, and black soil. The soil organic carbon and nitrogen densities were 5.51-25.25 and 0.37-0.80 kg·m^-2, respectively, and the C/N ratio was about 7.90-12.67. The eastern and northern parts of the belt had much higher carbon and nitrogen densities than the other parts of the belt, and upland soils had the highest organic carbon density ［(19.07±2.44) kg·m^-2］, forest soils had the highest nitrogen density ［(0.82±0.25) kg·m^-2］, while lowland soils had the lower organic carbon and nitrogen densities.

Nitrate leaching characteristics of wheat-corn rotation farmland in Guanzhong area of Shaanxi.

2010, 21(3):  640-646. 

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By using in situ leaching device, a field experiment was conducted to study the effects of nitrogen fertilization rate and straw mulching on the nitrate leaching at 90 cm soil depth, nitrate accumulation in soil profile (0-100 cm), crop yield, and nitrogen balance of wheat-corn rotation farmland in Guanzhong area of Shaanxi. Six treatments were installed, i.e., no fertilization (N₁,0 kg·hm^-2·a^-1), conventional fertilization (N₂, 471 kg·hm^-2·a^-1),recommended fertilization (N₃, 330 kg·hm^-2·a^-1), reduced N application (N₄, 165 kg·hm^-2·a^-1), increased N application (N₅, 495 kg·hm^-2·a^-1), and recommended fertilization plus straw mulching (N₃+S). The nitrate leaching loss was increased with increasing N fertilization rate. Excessive N fertilization and straw mulching could easily cause nitrate leaching. In treatment N₃+S, the annualNO₃^--N loss at 90 cm soil depth was the greatest (22.32 kg N·hm^-2), and the NO₃^--N loss from N fertilization was 16.44 kg N·hm^-2·a^-1, being 158.9% higher than that in treatment N_3. Nitrate mainly accumulated in 20-60 cm soil layer. When the N application rate was 330 kg N·hm^-2·a^-1, straw mulching had less effect on theNO₃^--N distribution in soil profile. No significant difference was observed in the crop yield among the treatments, but reduced N application (N₄) tended to decrease the yield. Under our experimental condition, a fertilization rate of 150 kg N·hm^-2·a^-1 for wheat and 180 kg N·hm^-2·a^-1 for maize could ensure the crop production and reduce the soil nitrate leaching and accumulation.

Evapotranspiration characteristics and crop coefficient of rain-fed maize agroecosystem.

2010, 21(3):  647-653. 

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Based on the eddy covariance flux data, meteorological gradient data, and ecological observation data, an analysis was made on the diurnal and seasonal dynamics of evapotranspiration from a rain-fed maize agroecosystem in the growth season of 2007. The diurnal and seasonal dynamics of the evapotranspiration could be both expressed as parabola curve, with the peak values appeared at about 12:00 and July, respectively. The crop coefficient of the agroecosystem was mainly affected by leaf area index (LAI), air temperature, net radiation, and surface soil moisture content. A statistical model of crop coefficient on half-hour scale was constructed.

Mathematical simulation of point source average infiltration depth under film hole irrigation.

2010, 21(3):  654-660. 

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By using RETC and SWMS-3D software, the point source infiltration characteristics of several typical soils under film hole irrigation were simulated, with the infiltration characteristics and related affecting factors analyzed. One simplified point source infiltration model with the parameters opening film hole rate, film hole diameter, soil clay particle content, and soil bulk density was established, and tested by infiltration experiments with the typical soils from Loess Plateau. It was shown that the infiltration coefficient under film hole irrigation increased with increasing opening film hole rate and decreased with increasing film hole diameter and soil clay particle content, while the infiltration index decreased with increasing opening film hole rate and soil clay particle content. This model could simply and accurately reflect the point source infiltration characteristics under film hole irrigation, and credibly determine the infiltration coefficient and index.

Effects of cinnamic acid on bacterial DNA polymorphorism in rhizosphere soil of cucumber under NaCl stress.

2010, 21(3):  661-667. 

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By using PCR-DGGE technique, this paper studied the effects of different concentration (0, 25, 50, 100, and 200 mg·kg^-1 soil) cinnamic acid on the bacterial DNA polymorphorism in rhizosphere soil of cucumber seedlings under the stress of 292.5 and 585 mg NaCl·kg^-1 soil. At all growth stages of cucumber seedlings, treatment 50 mg·kg^-1 of cinnamic acid had the similar band numbers and band gray scales in DGGE profiles to treatment 0 mg·kg^-1 of cinnamic acid, but the diversity index, richness index, and evenness index were the highest; while in treatments 100 and 200 mg·kg^-1 soil of cinnamic acid, the band numbers and band gray scales decreased, and the diversity index, richnes index, and evenness index were lower. Our results demonstrated that low concentration cinnamic acid relieved the salt stress on soil microbes, while high concentration cinnamic acid aggravated the stress. The cloning and sequencing results showed that the main bacterial groups affected by salt stress were uncultured bacterial species, α-roteobacteria, β-proteobacteria, and γ-proteobacteria, and a few were Firmicutes, Acidobacteria, and Actinobacteria.

Effects of nitrogen fertilization on leaf senescence, photosynthetic characteristics, yield, and quality of different flue-cured tobacco varieties.

2010, 21(3):  668-674. 

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Taking three flue-cured tobacco (Nicotiana tabacum L.) varieties Y5, Y7, and NC89 as test objects, this paper studied the effects of nitrogen fertilization on their leaf senescence, photosynthetic characteristics, yield, and quality. Increasing nitrogen supply increased the leaf superoxide dismutase (SOD) activity, chlorophyll content, and photosynthetic performance, and decreased the leaf malondialdehyde (MDA) content significantly. Accordingly, the leaf senescence was delayed. Compared with Y5 and NC89, variety Y7 had higher leaf MDA content and lower leaf SOD activity, chlorophyll content, and photosynthetic performance, and thus, its leaves senesced faster. High quality tobacco leaves with higher average price, gross value, superior leaves percentage, and reasonable chemical constituents were harvested under the application of 45 kg N·hm^-2,compared with applying 60 and 75 kg N·hm^-2. It was suggested that different flue-cured tobacco varieties had obvious differences in their leaf senescence physiological characteristics, and nitrogen fertilization played important roles in regulating their leaf senescence, yield, and quality. Appropriate nitrogen fertilization could improve the quality of tobacco leaves, and achieve higher economic benefits.

Effects of Ca²⁺ -carrier A23187 and Ca²⁺-chelator EGTA on the flower formation of chrysanthemum under photoperiodic induction and the Ca²⁺ distribution and carbohydrate contents in leaves during the flower formation.

2010, 21(3):  675-682. 

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This paper studied the effects of Ca²⁺ -carrier A23187 and Ca²⁺ -chelator EGTA on the bud differentiation of cut flower chrysanthemum (Dendranthema grandiflorium ‘Shenma’) under photoperiodic induction, as well as the Ca²⁺ distribution and the sucrose, soluble sugar, and starch contents in ‘Shenma’ leaves during the differentiation. In the control, the leaf Ca²⁺ content was lower at the vegetative stage of apical bud (Ⅰ), increased rapidly and reached a peak at the stage of initial differentiation (Ⅱ), and decreased then. At stage Ⅰ, the Ca²⁺ was mainly allocated in vacuole, cell wall, and cell lacuna; while at stage Ⅱ, it was more in cytoplasm. Compared with the control, the leaf Ca²⁺ content of A23187-treated plants increased significantly, and the days of initiation and ending of bud differentiation were advanced by 2 days and 3 days, respectively. On the other hand, the leaf Ca²⁺ content of EGTA-treated plants decreased significantly, and the days of initiation and ending of bud differentiation were postponed by 4 days and 8 days, respectively. For both A23187- and EGTA-treated plants, their leaf Ca²⁺  at stage Ⅱ was more allocated in cytoplasm. The leaf sucrose and soluble sugar contents of A23187-treated plants reached a peak on the 2nd day after treatment, and the time to reach the peak was shortened by 2 days, compared with the control, which was consistent with the peak time of Ca²⁺ . The leaf sucrose and soluble sugar contents of EGTA-treated plants had no significant changes on the 2nd day of treatment, but increased rapidly and reached the peak on the 8th day of treatment (stage Ⅱ), and then decreased. However, the leaf sucrose and soluble sugar contents during the whole period of bud differentiation were higher than those before photoperiodic induction. The leaf starch content of A23187-treated plants and the control decreased 2 days after treatment, while that of EGTA-treated plants began to decrease 8 days after treatment, and maintained at a lower level by the end of bud differentiation. The results indicated that Ca²⁺ and carbohydrates participated in the flower formation of chrysanthemum under photoperiodic induction.

Effects of exogenous Ca²⁺ on D₁ protein phosphorylation and PSⅡ performances of wheat leaf chloroplasts under high temperature and illumination stress.

2010, 21(3):  683-688. 

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Aimed to understand the effects of exogenous Ca²⁺ on the D₁ protein phosphorylation and PSⅡ performances of wheat leaf chloroplasts under high temperature and illumination stress, wheat leaves at grain-filling stage were sprayed with 10 mmol·L^-1 of CaCl₂ or water (as control), and then subjected to high temperature and illumination stress (35 ℃ and 1600 μmol·m^-2·s^-1) for various hours,  with the changes in photosynthetic electron transport rate (ETR), net photosynthetic rate, chlorophyll fluorescence parameters, and relative amount of phosphorylated and nonphosphorylated D₁ protein in thylakoid membranes determined. After spraying with Ca²⁺, the PSⅡ reaction center under the stress was reversibly inactivated, the net degradation of D-protein was effectively restrained, the D₁ protein phosphorylation was maintained at a higher level, and the ETR of whole chain and PSⅡ, the maximal photochemical efficiency of PSⅡ (F_v/F_m),  the actual photochemical efficiency of PSⅡ (Ф_PSⅡ),  the photochemical quenching coefficient (q_P ), and  net photosynthetic rate (P_n) were all higher, suggesting that exogenous Ca²⁺ could improve the PSⅡ performances and mitigate its damage under high temperature and illumination stress via regulating the turnover of D₁ protein in wheat leaf chloroplasts.

Effects of exogenous salicylic acid on protein expression level in Baphicacanthus cusia (Nees) Bremek leaves.

2010, 21(3):  689-693. 

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By using two-dimensional eletrophoresis method, this paper studied the protein expression level in Baphicacanthus cusia (Nees) Bremek leaves after sprayed with exogenous salicylic acid (SA). A total of significantly different 20 protein spots were obtained, among which, eight protein spots were indentified, being of ATP synthase, alpha tubulin, cell division protein, glyceraldehyde-phosphate dehydrogenase, and ACC oxidase, respectively. The expression abundance of all identified proteins was up-regulated, except for ACC oxidase which was down-regulated. Therefore, exogenous SA could affect the protein expression level in B. cusia leaves, and improve the plant resistance to environment stress and self-restoration capability.

Effects of temperature on mineralization and adsorption of exogenous amino acids and peptides in soil.

2010, 21(3):  694-700. 

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An incubation test was conducted to study the effects of different temperature (1 ℃, 15 ℃, and 25 ℃) on the mineralization and adsorption of exogenous amino acid and peptide in the soils of horticultural production systems, including organic farming system (OS), transitional farming system (TS), and conventional farming system (CS). With the increase of incubation temperature, the mineralization of exogenous amino acids and peptides in test soils quickened. The mean half-life (D₅₀) of Glu at 1 ℃, 15 ℃, and 25 ℃ was 13.3, 6.8, and 5.5 h, while the D₅₀ of Glu-Phe was 29.7, 7.5, and 4.4h, respectively. The adsorption rate of the exogenous amino acids and peptides was dependent on their concentrations and incubation temperature. The maximum adsorption rate (V_max) and affinity (K_m) of amino acids and the adsorption rate (V_h) of peptides were all increased with incubation temperature. In the range of 0-2.5 mmol·L^-1, the adsorption of amino acids conformed to classical Michaelis-Menten equation, while that of peptides conformed to linear equation. The turnover rate and the V_max,K_m, and V_h values of exogenous amino acids and peptides generally followed the series OS>TS>CS. In summary, temperature had significant effects on the mineralization and adsorption of exogenous amino acids and peptides in test soils.

Effects of land cover change on soil organic carbon and light fraction organic carbon at river banks of Fuzhou urban area.

2010, 21(3):  701-706. 

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By using Vario EL III element analyzer, the vertical distribution characteristics of soil organic carbon (SOC) and light-fraction organic carbon (LFOC) in the lawn, patch plantation, and reed wetland at river banks of Fuzhou urban area were studied in July 2007. For all the three land cover types, the SOC and LFOC contents were the highest in surface soil layer, and declined gradually with soil depth. Compared with reed wetland, the lawn and patch plantation had higher SOC and LFOC contents in each layer of the soil profile (0-60 cm), and the lawn had significantly higher contents of SOC and LFOC in 0-20 cm soil layer, compared with the patch plantation. After the reed wetland was converted into lawn and patch plantation, the SOC stock in the soil profile was increased by 94.8% and 72.0%, and the LFOC stock was increased by 225% and 93%, respectively. Due to the changes of plant species, plant density, and management measure, the conversion from natural wetland into human-manipulated green spaces increased the SOC and LFOC stocks in the soil profile, and improved the soil quality. Compared with the SOC, soil LFOC was more sensitive to land use/cover change, especially for those in 0-20 cm soil layer.

Spatiotemporal pattern of urban growth and its driving forces in urban agglomeration of central Liaoning Province, China.

2010, 21(3):  707-713. 

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Based on the five temporal  Landsat TM remote sensing data of 1988, 1992, 1997, 2000, and 2004, and by using GIS spatial analysis and landscape pattern analysis, this paper analyzed the spatiotemporal pattern of urban growth and its driving forces in the urban agglomeration of central Liaoning Province (UACLP). From 1988 to 2004, the urban area in the UACLP had being increased from 812.55 km² to 1345.86 km², with an average growth rate of 32.96 km² per year. The urban growth rate increased rapidly after 1997, and the urban growth intensity was up to the peak in 1997-2000. The urban growth was mainly concentrated in the central dense belt of the UACLP. From 1988 to 1997, the urban growth was relatively slow, its spatial pattern was compact, and edge growth and filling were the main urban growth types. From 1997 to 2004, the urban growth became faster with diffused spatial pattern and  complex patch shape, and “frog leap” and diffusion were the main urban growth types. Non-agricultural population growth, economic growth, urban spatial mutual attraction, industrial development, and development zones construction policies were the main driving forces of urban growth in the UACLP.

Landscape pattern and its dynamics in typical oasis-desert transitional zone of Minqin Region in 1960-2005.

2010, 21(3):  714-722. 

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By using ERDAS and GIS techniques, a systematic analysis was made on the landscape pattern and its dynamics in typical oasis-desert transitional zone of Minqin Region in 1960-2005. Forest land and cultivated land were the dominant factors leading to the landscape change. During the research period, oasis expanded toward the periphery by 2-3 km, and the transitional zone moved toward desert, with its width increased from 4 km in 1960 to about 9 km in 1987 and decreased rapidly then. In 1978-1987, the landscape change reached the historically highest level; but after 1998, the landscape pattern became relatively stable. In the whole transitional zone, the period with higher fragmented index occurred in 1978-1987, during which, the quickest variation among patch types was observed. The fragmentized regions were located in the area 2 km from oasis and in the forestation area. In 1960-1987, arbor forest tended to vanish. Shrubbery area increased widely before 1987, and decreased sharply since then. The intensity of land reclamation kept increasing in 1960-1998 but decreased after 1998, while the abandon rate had a trend of linear increase during the research period.

Changes of agroecosystem services value under effects of land consolidation.

2010, 21(3):  723-733. 

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This paper quantitatively described the changes of agroecosystem functions before (2003) and after (2007) the implementation of Gaolong land consolidation project in Hechuan of Chongqing. Engineering design and shadow price were  integrated to quantify the effects of the project on the functions, and cost-benefit analysis was used to further explain the economic meanings of the functions, and to analyze the changes of the agroecosystem services value under effects of the project. Compared with that before the land consolidation, the agroecosystem services value after the land consolidation was somewhat improved, with the largest increment of nutrient cycling function and the smallest change of soil conservation function. In the implementation of the project, the changes of the agroecosystem services value induced by farmland water conservancy, field road building, and land-leveling engineering mainly manifested in the change of disturbance function. From the 7th to 35th year after the project, the cost benefit would have a rapid increase, and tended to be stable after then, giving a weak ecological pressure and little services value loss, and benefiting the improvement of regional ecological environment.

Bioaccumulation of sediment heavy metals in Bellamya aeruginosa and its relations with the metals geochemical fractions.

2010, 21(3):  734-742. 

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A 28-day sediment bioaccumulation test was conducted to study the bioaccumulation of river sediment heavy metals in Bellamya aeruginosa, and its relations with the geochemical fractions of the metals. A higher bioaccumulation of Cd, Pb, Cu, Cr, Zn, and Mn was found in the hepatopancreas of B. aeruginosa, with the greatest accumulation of Zn (84.32%±4.36%), followed by Cu (7.67%±2.84%), Pb (3.62%±1.84%), Cr (2.22%±1.03%), Mn (1.33%±0.15%), and Cd (0.83%±0.53%). No significant correlations were observed between the heavy metals accumulations in B. aeruginosa hepatopancreas, but the significant positive correlation between the metals pollution index of hepatopancreas and the Nemerow pollution index of sediments suggested that B. aeruginosa could be used as a potential bioindicator for sediment heavy metals pollution. The biota-sediment accumulation factors (BSAFs) for Cd, Cr, Zn, and Mn from different sediments showed a higher variability, while the BSAFs for Cu and Pb were relatively constant. The bioaccumulation of Cd had significant correlations with exchangeable Cd, weak acid soluble Cd, and oxidizable Cd; Pb bioaccumulation had significant correlation with reducible Pb; Cu bioaccumulation had significant correlation with oxidizable Cu; while Cr and Mn bioaccumulation had no correlations with the total concentrations and geochemical fractions of the two metals. Therefore, it would be inappropriate to use the BSAF as the indicator for the bioaccumulation of heavy metals in B. aeruginosa.

Control efficacy of Trichogramma japonicum against Chilo suppressalis and Chilaraea auricilia.

2010, 21(3):  743-748. 

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In order to understand the relationships of the population increase capacities between egg parasitoid Trichogramma japonicum Ashmead(Hymenoptera: Trichogrammatidae) and two rice borers Chilo suppressalis Walker and Chilaraea auricilia Dudgeon (Lepidoptera: Pyralidae), and to evaluate the control efficacy of T. japonicum against C. suppressalis and C. auricilia, life table method was adopted to establish the experimental population life tables of the two rice borers and the population fecundity tables of T. japonicum on the two hosts, and to estimate the fecundity and parasitism capacity of T. japonicum on the two hosts. The generation period （T） of C. suppressalis and C. auricilia was 56.40 d and 47.80 d, and their intrinsic rate of natural increase (r_m) was 0.0489 and 0.072; while the T of T. japonicum on C. suppressalis and C. auricilia was 9.75 d and 9.78 d, and the r_m was 0.3154 and 0.3161, respectively. These parameters indicated that T. japonicum could control the two rice borers effectively.

Feeding habits of Trichiurus lepturus in Beibu Gulf of South China Sea.

2010, 21(3):  749-755. 

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From August 2008 to September 2009, the feeding habits of Trichurus lepturus L. in Beibu Gulf of South China Sea were studied by monthly sampling
and stomach content analysis. In study area, T. lepturus was euryphagous, which fed on fish, cephalopoda, benthic crustacean, and zooplankton, etc., among which, Bregmaceros rarisquamosu, Decapterus maruadsi, and Acetes chinensis were the main prey components, accounting for 37.99%, 16.42%, and 10.03%, respectively. D. maruadsi and Anchoviella heteroloba appeared throughout the Beibu Gulf all year round, and could be served as the index species for the migration and fishing ground distribution of T. lepturus. The indices feeding intensity and stomach fullness differed significantly among seasons (P<0.001); while the index prey diversity had no significant seasonal difference (P>0.05), which peaked in autumn and had an annual average value of 1.97. Cluster analysis revealed that when the preanal length of T. lepturus was 190 mm, i.e., at 50% of maturity length, a clear diet shift happened, from small zooplankton, pelagic fishes, and crustacean for the juveniles to predominantly larger fish and cephalopoda for the adults.

Age identification and growth characteristics of Katsuwonus pelamis in western and central Pacific Ocean.

2010, 21(3):  756-762. 

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Fish age and growth are the important biological parameters for the assessment of fishery resources. With the help of purse seiners, 262 individuals of skipjack tuna (Katsuwonus pelamis) were sampled from western and central Pacific Ocean in October 2007-January 2008. The measurements in situ showed that the fork length of the samples ranged from 278 to 746 mm, and their body mass ranged from 345 to 9905 g. The first dorsal spine of each individual was collected for age identification and growth parameters estimation. The relationship between fork length (L,mm) and body mass (M,g) was expressed as M=3.612×10^-6L^{3. 278} （R²=0.9782）,and no significant difference was found for the males and females (F=2.002,P>0.05). A comparison with Akaike information criterion (AIC) suggested that among power regression equation, linear regression equation, and exponential regression equation, linear regression equation was most suitable for describing the relationship between fork length and spine radius (AIC=2257.4). The mean back-calculated fork lengths of K. pelamis with the ages of 1-5 estimated by FraserLee’s method were 398.4, 494.2, 555.4, 636.8, and 728.8 mm, respectively. Residual analyses indicated that there was no significant difference in the growth of male and female K. pelamis (F=0.670;df=182;P>0.05). The sex-combined von Bertalanffy growth equation of K. pelamis was L_t=706.51(1-e^{-0.64(t+0.037)}).

Physical and chemical properties of land-filling pile and aged refuse in 5-year-old semi-aerobic and anaerobic landfills.

2010, 21(3):  763-769. 

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This paper studied the surface settlement, temperature, and gas production of land-filling pile, and the physical and chemical properties of aged refuse in 5-year-old semi-aerobic and anaerobic landfills. The pile’s surface settlement and its volume reduction rate were significantly higher in semi-aerobic than in anaerobic landfill; and the treatment with leachate recycling brought larger uneven settlement than the treatment with water recycling. The temperature of anaerobic landfill pile (25.6 ℃) was slightly higher than that of semi-aerobic landfill file (24.8 ℃), but the difference was not significant. During land-filling period, the O₂ concentration in semi-aerobic landfill pile was significantly higher than that in anaerobic one, while the CH₄ concentration was in reverse. After 5 years land-filling, the contents of easily degradable organic matters in aged refuse, such as kitchen refuses and papers, decreased dramatically, while the contents of plastics, glasses, bricks, and woods increased. In addition, the contents of organic matters and nutrients in aged refuse were higher than those in typical southern China soils, and the concentrations of heavy metals except chromium in anaerobic landfill aged refuse were not beyond the grade three of Environmental Quality Standards for Soils (GB 15618-1995).

Applications of GIS in biomass energy source research

2010, 21(3):  770-776. 

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Biomass resources have the characteristics of widespread and dispersed distribution, which have close relations to the environment, climate, soil, and land use, etc. Geographic information system (GIS) has the functions of spatial analysis and the flexibility of integrating with other application models and algorithms, being of predominance to the biomass energy source research. This paper summarized the researches on the GIS applications in biomass energy source research, with the focus in the feasibility study of bioenergy development, assessment of biomass resources amount and distribution, layout of biomass exploitation and utilization, evaluation of gaseous emission from biomass burning, and biomass energy information system. Three perspectives of GIS applications in biomass energy source research were proposed, i.e., to enrich the data source, to improve the capacity on data processing and decision-support, and to generate the online proposal.

Nonpoint source pollution in Northeast China: Research advance.

2010, 21(3):  777-784. 

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In order to understand the research trend on nonpoint source (NPS) pollution in Northeast China and to find its problems and shortcomings, the related research findings from 1991 to 2008 were searched, categorized, and statistically analyzed, so that the regional strategies could be employed to bring water pollution under control. Overall, the research on NPS pollution in Northeast China had an increasing trend, and the research contents included investigation and assessment, quantification of pollution load, mechanisms of pollutants translocation, modeling simulation, and prevention and control. The research interests were nitrogen, phosphorus, sediments, pesticides, and heavy metals. Empirical methods rather than mechanism models were more used to estimate the pollution load, and the researches were more on agricultural rather than urban NPS pollution. The control and management of NPS pollution was remained in soil and water conservation, and lacked of optimal collection assessment for soil and water conservation measures and of assessment for optimal management methods. At present, the research was overall at the stage of theoretical exploration, and controversy remained whether the nonpoint source was major source or not. Incoming researches should focus on the measure application, assessment, basic data collection, determination of regional NPS pollutants, quantification of pollution load, and invention of new technologies; and multi-disciplinary corporation should be strengthened to supply scientific bases for regional water environmental control and prevention.

Odor pollution from landfill sites and its control: A review.

2010, 21(3):  785-790. 

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Landfill sites are the major sources of offensive odor in urban public facilities. With the progress of urbanization and the residents’ demands for a higher living environment quality, the odor emission from landfill sites has become a severe pollution problem, and the odor control at landfill sites has been one of the research hotspots. This paper summarized the main components and their concentrations of the odor from landfill sites, and expatiated on the research progress in the in-situ control of the odor. The further research directions in in-situ control of the odor from landfill sites were prospected.

Land cover classification of Four Lakes Region in Hubei Province based on MODIS and ENVISAT data.

2010, 21(3):  791-795. 

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Based on the differences of back scattering coefficient in ENVISAT ASAR data, a classification was made on the towns, waters, and vegetationcovered areas in the Four Lakes Region of Hubei Province. According to the local cropping systems and phenological characteristics in the region, and by using the discrepancies of the MODIS-NDVI index from late April to early May, the vegetation-covered areas were classified into croplands and non-croplands. The classification results based on the above-mentioned procedure was verified by the classification results based on the ETM data with high spatial resolution. Based on the DEM data, the non-croplands were categorized into forest land and bottomland; and based on the discrepancies of mean NDVI index per month, the crops were identified as mid rice, late rice, and cotton, and the croplands were identified as paddy field and upland field. The land cover classification based on the MODIS data with low spatial resolution was basically consistent with that based on the ETM data with high spatial resolution, and the total error rate was about 13.15% when the classification results based on ETM data were taken as the standard. The utilization of the above-mentioned procedures for large scale land cover classification and mapping could make the fast tracking of regional land cover classification.

Distribution and accumulation of mineral nitrogen in apple orchard soils in dry plateau of eastern Gansu Province.

2010, 21(3):  796-800. 

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This paper studied the distribution and accumulation characteristics of mineral nitrogen in the soils of different years old apple orchards in dry plateau of eastern Gansu Province. The soil ammonium nitrogen content was increased with the increase of planting year. In the 2-3, 5, 10, 15, 20, and 22 years old apple orchards, the ammonium nitrogen content in 0-120 cm soil layer was 3.3, 5.8, 6.5, 9.1, 12.1, and 15.3 mg·kg^-1, respectively, and 0-60 cm soil layer had a higher ammonium nitrogen content than 60-120 cm soil layer. For all the apple orchards, the nitrate nitrogen content in 0-40 cm soil layer was relatively low, but increased with increasing depth. The soil nitrate nitrogen content also increased with the increase of planting year, which reached 2602.5 kg·hm^-2 in the 0-120 cm soil layer of 22 years old apple orchard. It was concluded that in the apple orchards in dry plateau of eastern Gansu Province, soil ammonium nitrogen was more accumulated in upper layers, while nitrate nitrogen was more accumulated in deeper layers.

Affecting factors on capture efficacy of sex pheromone traps for Cydia pomonella L .

2010, 21(3):  801-806. 

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Codling moth Cydia pomonella L. (Lepidoptera, Olethreutidae) is the most serious pest of orchards, and one of the most important quarantine pests in China. This paper studied the effects of the color, shape, placement location, lure color, and lure number of sex pheromone traps on the capture efficacy for C. pomonella L. male moth. It was found that the capture efficacy of white and green traps was two times higher than that of blue trap (P<0.05), and water bottle and triangle traps had no significant difference in their trapping effect. The traps hung in the middle of crown gave two times higher catches than those hung in the upper portion of crown (P<0.05). Lure color and number had no significant effect on the capture efficacy. The present results could be used in better monitoring C. pomonella by using its sex pheromones.