Table of Content

18 November 2015, Volume 26 Issue 11

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Litter decomposition and lignocellulose enzyme activities of Actinothuidium hookeri and Cystopteris montana in alpine timberline ecotone of western Sichuan, China.

CHEN Ya-mei, HE Run-lian, DENG Chang-chun, YANG Wan-qin, ZHANG Jian, YANG Lin, LIU Yang

2015, 26(11):  3251-3258. 

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The mass loss and lignocellulose enzyme activities of Actinothuidium hookeri residues and Cystopteris montana leaf litter in coniferous forest and timberline of western Sichuan, China were investigated. The results showed that both the mass loss rates of A. hookeri and C. Montana in timberline were higher than those in coniferous forest, while enzyme activities in timberline were lower than those  in coniferous forest which was contrast with the hypothesis. The mass loss of two ground covers had significant differences in different seasons. The mass loss rate of A. hookeri in snowcovered season accounted for 69.8% and 83.0% of the whole year’s in timberline and coniferous forest, while that of C. montana in the growing season accounted for 82.6% and 83.4% of the whole year’s in timberline and coniferous forest, respectively. C. montana leaf litter decayed faster in the growing season, which was consistent with its higher cellulase activity in the growing season. The result illustrated that the enzymatic hydrolysis of cellulose and hemicellulose might be the main driving force for the early stage of litter decomposition. Multiple linear regression analysis showed that environmental factors and initial litter quality could explain 45.8%-85.1% variation of enzyme activity. The enzyme activities of A. hookeri and C. montana in the process of decomposition were mainly affected by the freezethaw cycle in snowcovered season.

Fine root production in initial stage of Castanopsis carlesii under different regeneration modes in Sanming, Fujian Province, China.

HU Shuang-cheng1,2, XIONG De-cheng1,2, HUANG Jin-xue1,2, DENG Fei1,2, CHEN Yun-yu1,2, LIU Xiao-fei1,2, CHEN Guang-shui1,2

2015, 26(11):  3259-3267. 

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Fine root biomass and production in initial stage of three different regeneration approaches, i.e., natural regeneration with anthropogenic promotion (AR), the Castanopsis carlesii plantation (CC) and the Cunninghamia lanceolata plantation (CL) on the clearcutting sites of the secondary forest of C. carlesii (CK), in Sanming, Fujian Province, were investigated by using both minrhizotrons and the soil coring methods. The results of a year observation showed that the average fine root biomass was 422.5, 253.1, 197.2 and 162.8 g·m^-2, and the fine root production  was 284.0, 182.6, 136.7 and 15.4 g·m^-2·a^-1 for AR, CC, CL and CK, respectively. The maximum value of production was found in spring for AR and CC, in autumn for CL, and in winter for CK. Fine root production of other plants was higher than that of target tree species in CC, and  vice verse in CL. There was a significant positive correlation between monthly fine root production and monthly precipitation in AR and CC. Significant positive correlation was found between monthly fine root production of other plants and monthly temperature in CL. The fine root under annual production and annual average biomass of these three young forests mainly distributed in the soil layer of 20-40 cm, and mainly in the diameter class of 0-1 mm. The study demonstrated that the biomass and production of fine root under anthropogenic promotion were greater than that of the plantation, and the method of anthropogenic promotion were more conducive to increase the returning of organic matter, improve soil fertility, and maintain a high productivity in initial stage of forest regeneration.

Seasonal dynamics of carbon and nitrogen in fine roots and their differences between successive rotation poplar plantations.

WANG Yan-ping1,2, XU Tan3, ZHU Wan-rui1, WANG Hua-tian1,2, ZHANG Guang-can1,2, LI Chuan-rong2, JIANG Yue-zhong4

2015, 26(11):  3268-3276. 

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In this study, poplar fine roots in two successive rotation plantations were sampled over seasons. Root samples were grouped from first to five orders to examine the seasonal dynamics of carbon and nitrogen contents of poplar fine roots with orders, and compared their differences between two successive rotation plantations, and finally to find the relationships between the fine root growth and the productivity decline of successive rotation poplar plantations. The results showed that nonstructure carbohydrates (NSC) content increased significantly with root orders, while nitrogen content decreased. The contents of total carbon and NSC were significantly related to total nitrogen content. Root orders explained 98.2% variance of carbon and nitrogen contents of poplar fine roots, and the difference between rotations only explained 1.7% of variance. Poplar fine roots consisted of more carbon and less nitrogen with root orders, and the seasonal changes in contents of total carbon, total nitrogen and NSC showed significant difference between rotations, while that of the C:N ratio didn’t show significant difference. Root order and season showed interaction effect on carbon and nitrogen dynamic. The C:N ratio was about 20:1 in lower order roots,  and more than 30:1 in higher order roots. The C:N ratio in summer and autumn was significantly less than those in other seasons, while NSC content was the highest in November. This study indicated that the allocation of carbon and nitrogen in fine roots was closely correlated with fine root orders. Both NSC content and C:N ratio were of greatly important ecological significance in fine root turnover and growth regulation.

 

Root anatomical structure and hydraulic traits of three typical shrubs on the sandy lands of northern Shaanxi Province, China.

AI Shao-shui1, LI Yang-yang2,3, CHEN Jia-cun3, CHEN Wei-yue1

2015, 26(11):  3277-3284. 

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Root xylem anatomical structure and hydraulic traits of three typical shrubs, i.e., Salix psammophila, Caragana korshinskii and Hippophae rhamnoides, within two soil layers (0-20 cm and 30-50 cm) were compared. The results showed that S. psammophila had a higher leaf water potential than C. korshinskii and H. rhamnoides, the average maximum and minimum lumen diameter (d_max and d_min, respectively), the average lumen area of vessels (A_lum) and the ratio of lumen area of all vessels to xylem area (A_ves/A_xyl) in S. psammophila roots were also significantly higher than those in C. korshinskii and H. rhamnoides, and the root vessel density (VD) in S. psammophila was the same as that in H. rhamnoides but significantly higher than that in C. korshinskii. Root hydraulic conductivity in S. psammophila was 5  times of C. korshinskii and 2.8 times of H. hamnoides. The vulnerability index in S. psammophila roots was similar to that in C. korshinskii but higher than that in H. hamnoides. S. psammophila belonged to a waterspending species, whereas both C. korshinskii and H. rhamnoides were watersaving species, and C. korshinskii was more droughtresistant than H. rhamnoides. There was no difference of d_max, d_min and A_lum between roots in two soil layers, but roots within in the 30-50 cm soil layer had larger VD and A_ves/A_xyl. The root specific hydraulic conductivity within the 30-50 cm soil layer was significantly higher than within the surface soil layer, whereas the vulnerability index within the 30-50 cm soil layer was smaller, indicating roots in deep soil layers had higher hydraulic transport efficiency and lower hydraulic vulnerability.

Time lag effects of throughfall in natural Larix gmelinii forest in the north of Great Xing’〖KG-*4〗an Mountains, China.

LIU Yu-jie, MAN Xiu-ling, SHENG Hong-cai

2015, 26(11):  3285-3292. 

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Based on a natural Larix gmelinii forest from Mohe Ecological Station, located in north of Great Xing’an Mountains, time lag effects of throughfall inside the Larix gmelinii forest were analyzed by measuring rainfall, throughfall and stemflow with the method of location observation. The result showed that forest throughfall, stemflow and canopy interception accounted for 76.5%, 2.6% and 20.9% of total rainfall, respectively. Time lag of rainfall inside L. gmelinii forest was found both in beginning and termination of rainfall compared to outside, and the higher the rainfall level, the shorter the time lag of throughfall. For throughfall and stemflow, variations of time lag were (67.8±7.8)-(17.2±3.9) min and (112.0±38.8)-(48.3±10.6) min, respectively. The time lag of throughfall decreased with the increasing rainfall intensity under the same rainfall level. When the rainfall intensity was greater than 2 mm·h^-1, the time lag of throughfall was shortened significantly, but it increased with prolonging the antecedent dry period before rainfall. Rainfall would be the critical factor to affect the time lag of throughfall when the antecedent dry period was longer than 48 h. Termination of throughfall also lagged when rainfall termination happened with a rainfall greater than 5.0 mm. The time lag of throughfall termination increased with increasing the rainfall intensity, but it had no significant relationship with the antecedent dry period before rainfall. However, the termination of stemflow occurred prior to
rainfall, which was relevant to the rainfall level, and the smaller the rainfall level, the sooner the stemflow terminated.

Physiological response and salttolerance of Gleditsia microphylla under NaCl stress.

LU Bin1, HOU Yue-min2, LI Xin-yang1, CHANG Yue-xia1, HUANG Da-zhuang1,3, LU Bing-she1,3

2015, 26(11):  3293-3299. 

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In order to exploit the salttolerance ability and mechanism of Gleditsia microphylla, the plant growth, cell membrane permeability, the activities of cell protective enzymes, and the distributions of Na⁺ and K⁺ in different tissues were investigated under various NaCl stress (0.053%, 0.15%, 0.3%, 0.45% and 0.6%) with potted twoyear seedlings. The results were as follows: With the increase of NaCl concentration, the seedling growth decreased while the salt injured index increased, and the salttolerance thresholds of seedling was 0.42% NaCl. With the NaCl concentration increasing, the membrane permeability, superoxide anion radical generating rate and MDA content increased grandly, while the activities of SOD, POD and CAT demonstrated an increasedecrease curve which reached the peak at 0.3% or 0.45%. Under the high salt stress condition, the superoxide anion could be consumed timely by increasing the activities of SOD, POD and CAT enzymes, which was useful to avoid cell injure. Under salt stress condition, the Na⁺ content in different tissues increased gradually, following the order of root > leaf > stem, and the K⁺ content and K⁺/Na⁺ in different tissues decreased, following the order of leaf > root > stem. The K⁺-Na⁺ selective transportation coefficients (S_K⁺·Na⁺) of stem and leaf tissues under the soil NaCl stress condition were both increased, following  the order of leaf > stem. In conclusion, the findings suggested that the saltadaptation mechanisms of G. microphylla were root saltrejection by Na⁺ accumulation and restriction in root tissue and leaf salttolerance by a remarkably increased ability of K⁺ selective absorption and accumulation in leaf tissue.

Effects of exogenous glucose and starch on soil carbon metabolism of root zone and root function in potted sweet cherry.

ZHOU Wen-jie1,2, ZHANG Peng1,2, QIN Si-jun1,2, LYU De-guo1,2

2015, 26(11):  3300-3308. 

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One-year-old potted sweet cheery trees were treated with 4 g·kg^-1 exogenous glucose or starch and with nonaddition of exogenous carbon as the control for up to 60 days. Soil of root zone was sampled to analyze soil microbial biomass carbon, activities of invertase and amylase and microbial community functional diversity during the 60day treatment, and roots were sampled for analysis of root respiratory rate, respiratory pathways and root viability after treatment for 30 days. Results showed that the invertase activity and the microbial biomass carbon  initially increased and decreased subsequently, with the maxima which were 14.0% and 13.1% higher in the glucose treatment than in the control treatment appeared after 15 and 7 days of treatments, respectively. Soil organic matter content increased first then decreased and finally moderately increased again. Amylase activity was 7.5fold higher in the starch treatment than in the control treatment after 15-day treatment. Soil microbial biomass carbon  was higher in the starch treatment than in the control treatment except after 7-day treatment. Soil organic matter content initially increased and then decreased, but it was still 19.8% higher than in the control after 60day treatment. BIOLOG results showed that the maximum average well color development (AWCD) value and microbial activity appeared after 15-day treatment in the following order: starch>glucose>control. After 30-day treatment, glucose treatment resulted in a significant increase in the soil microbial utilization of carbohydrates, carboxylic acid, amino acids, phenolic acids and amines, and starch treatment significantly increased the soil microbial utilization of carbohydrates, carboxylic acid, polymers and phenolic acids. After 30-day treatment, the total root respiratory rate and root viability were 21.4%, 19.4% and 65.5%, 37.0% higher in glucose treatment than in the control and starch treatments, respectively. These results indicated exogenous glucose and starch affected soil carbon metabolism and enhanced soil microbial activity, the root respiratory rate and root viability.

Effects of Cuscuta australis parasitism on the growth, reproduction and defense of Solidago canadensis. 

YANG Bei-fen1,2, DU Le-shan3, LI Jun-min1,2

2015, 26(11):  3309-3314. 

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In order to find out how parasitic Cuscuta australis influences the growth and reproduction of Solidago canadensis, the effects of the parasitism of C. australis on the morphological, growth and reproductive traits of S. canadensis were examined and the relationships between the biomass and the contents of the secondary metabolites were analyzed. The results showed that the parasitism significantly reduced the plant height, basal diameter, root length, root diameter, root biomass, stem biomass, leaf biomass, total biomass, number of inflorescences branches, axis length of inflorescence, and number of inflorescence. In particular, plant height, number of inflorescence and the stem biomass of parasitized S. canadensis were only 1/2, 1/5 and 1/8 of nonparasitized plants, respectively. There was no significant difference of plant height, root length, stem biomass and total biomass between plants parasitized with high and low intensities. But the basal diameter, root volume, leaf biomass, root biomass, the number of inflorescences branches, axis length of inflorescence and number of inflorescence of S. canadensis parasitized with high intensity were significantly lower than those of plants parasitized with low intensity. The parasitism of C. australis significantly increased the tannins content in the root and the flavonoids content in the stem of S. canadensis. The biomass of S. canadensis was significantly negatively correlated with the tannin content in the root and the flavonoids content in the stem. These results indicated that the parasitism of C. australis could inhibit the growth of S. canadensis by changing the resources allocation patterns as well as reducing the resources obtained by S. canadensis.

Effects of postponing nitrogen application on photosynthetic characteristics and grain yield of winter wheat subjected to water stress after heading stage.

YANG Ming-da1,2, MA Shou-chen3, YANG Shen-jiao4, ZHANG Su-yu2, GUAN Xiao-kang2, LI Xue-mei1, WANG Tong-chao2, LI Chun-xi1

2015, 26(11):  3315-3321. 

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A pot culture experiment was conducted to study the effects of postponing nitrogen (N) application on photosynthetic characteristics and grain yield of winter wheat subjected to water stress after heading stage. Equal in the total N rate in winter wheat growth season, N application was split before sowing, and/or at jointing and /or at anthesis at the ratio of 10:0:0 (N₁), 6:4:0 (N₂) and 4:3:3 (N₃), combined with unfavorable water condition (either waterlogged or drought) with the sufficient water condition as control. The results showed that, under each of the water condition, both N₂ and N₃ treatments significantly improved the leaf photosynthetic rate and the SPAD value of flag leaf compared with N₁ treatment during grain filling stage, and also the crop ear number, grain number per spike and aboveground biomass were increased. Although postponing nitrogen application increased water consumption, both grain yield and water use efficiency were increased. Compared with sufficient water supply, drought stress and waterlogging stress significantly reduced the photosynthetic rate of flag leaves at anthesis and grain filling stages, ear number, 1000grain mass and yield under all of the N application patterns. The decline of photosynthetic rate under either drought stress or waterlogging stress was much less in N₂ and N₃ than in N₁ treatments, just the same as the grain yield. The results indicated that postponing nitrogen application could regulate winter wheat yield as well as its components to alleviate the damages caused by unfavorable water stress by increasing flag leaf SPAD and maintaining flag leaf photosynthetic rate after anthesis, and promoting aboveground dry matter accumulation.

Effect of long-term shallow tillage and straw returning on soil potassium content and stratification ratio in winter wheat/summer maize rotation system in Guanzhong Plain, Northwest China.

SHI Jiang-lan, LI Xiu-shuang, WANG Shu-juan, LI Shuo, LI You-bing, TIAN Xiao-hong

2015, 26(11):  3322-3328. 

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Soil stratified sampling method and potassium chemical fractionation analysis were used to investigate effects of long-term shallow tillage and straw returning on soil K contents and stratification ratios in winter wheat/summer maize rotation system in Guanzhong Plain of Northwest China. The results showed that after 13-year continuous shallow tillage and straw returning, surface accumulation and stratification effect obviously occurred for soil available K (SAK) and nonexchangeable K (NEK), which was particularly remarkable for SAK and its fractions. Serious depletion of SAK occurred in 15-30 cm soil layer, and the SAK value was lower than the critical value of soil potassium deficiency. Meanwhile, significant differences were found between SR₁ and SR₂ values of SAK and its fractions, SR was obtained by values of topsoil layer (0-5 cm) divided by corresponding values of lower soil layers (5-15 cm layer, SR₁, or 15-30 cm layer, SR₂). However, no significant difference was observed between SR values of NEK and mineral K. In conclusion, returning of all straw  over 10 years  in the winter wheat/summer maize rotation system contributed greatly to maintaining soil K pool balance, while special attention should be paid to the negative effects of surface accumulation and stratification of SAK on soil K fertility.

Effects of  spacing on the yields and canopy structure of japonica rice at full heading stage.

LI Xiao-peng, WANG Shu, HUANG Yuan-cai, JIA Bao-yan, WANG Yan, ZENG Qun-yun

2015, 26(11):  3329-3336. 

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With three panicle types of rice varieties and hybrids in Liaoning as entries, the effects of  spacing of Japonica rice on light interception capacity, population light distribution, light conversion efficiency at full heading stage and yield were studied. The results showed that the leaf area indices at full heading stage, closely related to light interception, increased first and then decreased with the decrease of transplanting density. The extinction coefficient in one day increased first and then decreased, and the K value increased with the increase of planting density. Yield was positively correlated with canopy extinction coefficient and inclinations of the upper three leaves. In terms of energy efficiency, the yields were positively correlated to flag leaf stomatal conductance, intercellular CO₂ concentration and transpiration rate. At the configuration of high (15 cm×25 cm) and low （20 cm×30 cm and 20 cm×35 cm) densities, Japonica rice could increase light interception capability and optical conversion efficiency, but could not obtain high and stable yields due to limitation by lodging and panicles of per unit area, respectively. At the configurations of 15 cm×30 cm and 20 cm×25 cm, it was easy to get adequate panicles, optimize the structure of the canopy, reduce lodging risk, and obtain high yield.

Effects of elevated atmospheric CO₂ and nitrogen application on cotton biomass, nitrogen utilization and soil urease activity.

LYU Ning1, YIN Fei-hu1, CHEN Yun2, GAO Zhi-jian2, LIU Yu2, SHI Lei2

2015, 26(11):  3337-3344. 

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In this study, a semiopentop artificial climate chamber was used to study the effect of CO₂ enrichment (360 and 540 μmol·mol^-1) and nitrogen addition (0, 150, 300 and 450 kg·hm^-2) on cotton dry matter accumulation and distribution, nitrogen absorption and soil urease activity. The results showed that the dry matter accumulation of bud, stem, leaf and the whole plant increased significantly in the higher CO₂ concentration treatment irrespective of nitrogen level. The dry matter of all the detected parts of plant with 300 kg·hm^-2 nitrogen addition was significantly higher than those with the other nitrogen levels irrespective of CO₂ concentration, indicating reasonable nitrogen fertilization could significantly improve cotton dry matter accumulation. Elevated CO₂ concentration had significant impact on the nitrogen absorption contents of cotton bud and stem. Compared to those under CO₂concentration of 360 μmol·mol^-1, the nitrogen contents of bud and stem both increased significantly under CO₂ concentration of 540 μmol·mol^-1. The nitrogen content of cotton bud in the treatment of 300 kg·hm^-2 nitrogen was the highest among the four nitrogen fertilizer treatments. While the nitrogen contents of cotton stem in the treatments of 150 kg·hm^-2 and 300 kg·hm^-2 nitrogen levels were higher than those in the treatment of 0 kg·hm^-2 and 450 kg·hm^-2 nitrogen levels. The nitrogen content of cotton leaf was significantly influenced by the interaction of CO₂ elevation and N addition as the nitrogen content of leaf increased in the treatments of 0, 150 and 300 kg·hm^-2 nitrogen levels under the CO₂ concentration of 540 μmol·mol^-1. The nitrogen content in cotton root was significantly increased with the increase of nitrogen fertilizer level under elevated CO₂ (540 μmol·mol^-1) treatment. Overall, the cotton nitrogen absorption content under the elevated CO₂ (540 μmol·mol^-1) treatment was higher than that under the ambient CO₂ (360 μmol·mol^-1) treatment. The order of nitrogen accumulation content in organs was bud>leaf>stem >root. Soil urease activity of both layers increased significantly with the elevation of CO₂ concentration in all the nitrogen treatments. Under each CO₂ concentration treatment, the soil urease activity in the upper layer (0-20 cm) increased significantly with nitrogen application, while the urease activity under the application of 300 kg·hm^-2 nitrogen was highest in the lower layer (20-40 cm).  The average soil urease activity in the upper layer (0-20 cm) was significantly higher than that in the lower layer (20-40 cm). This study suggested that the cotton dry matter accumulation and nitrogen absorption content were significantly increased in response to the elevated CO₂ concentration (540 μmol·mol^-1) and higher nitrogen addition (300 kg·hm^-2).

Effects of potato/soybean intercropping on photosynthetic characteristics and yield of three soybean varieties.

CHEN Guang-rong1,2, YANG Wen-yu1, ZHANG Guo-hong2, WANG Li-ming2, YANG Ru-ping2, YONG Tai-wen1, LIU Wei-guo1

2015, 26(11):  3345-3352. 

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The potato/soybean intercropping trials using three soybean varieties including Zhonghuang 30 (early-maturing variety), Jidou 17 (mid maturing variety) and Qihuang 34 (late maturing variety) with the sole cropping potato as contro1 were carried out to determine the dynamic changes of leaf area index (LAI) of soybean, accumulation of dry matter, photosynthetic characteristics, yield and yield components. The results showed that the LAI, dry matter accumulation, net photosynthesis (P_n), transpiration rate (T_r) and stomatal conduction (g_s) of soybean in all intercropping systems were lower than in monoculture because of the influence of intensified lower light during earlier growing stage, and the duration from planting to flowering was extended. When the potato was harvested, the LAI, dry matter accumulation, P_n, T_r and g_s of soybean in all intercropping systems increased, especially for midmaturing and latematuring varieties, which became much closer to those in the monoculture. Compared with sole cropping, the pods per plant, seeds per plant and seeds per pod in intercropping system significantly decreased by 22.0%, 36.0% and 17.6% for earlymaturing soybean, 5.1%, 13.1% and 8.9% for midmaturing soybean, 5.7%, 7.6% and 2.1% for latematuring soybean, respectively. The yields of midmaturing and latematuring varieties in intercropping systems were higher than that of the earlymaturing, which increased by 92.4% and 163.4%, with the land equivalent ratio (LER) of 1.81 and 1.84, respectively. This suggested that midmaturing and latematuring soybean varieties were suitable for intercropping with the potato to improve photosynthetic efficiency, dry matter accumulation and yield of intercropping soybean.

Effects of nitrogen management on yield, quality, nitrogen accumulation and its transportation of watermelon in gravelmulched field.

MA Zhong-ming1, DU Shao-ping2, XUE Liang3

2015, 26(11):  3353-3360. 

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The effects of nitrogen management on yield, quality, nitrogen and dry matter accumulation and transportation of watermelon in sand field were studied based on a field experiment. The results showed that too low or too high basal nitrogen fertilization was unfavorable to seedling growth of watermelon in sand field, and no nitrogen application at vine extension or fruiting stages limited the formation of ‘source’ or ‘sink’. At the same nitrogen rate, compared with the traditional T₁ treatment (30% basal N fertilizer + 70% N fertilizer in vine extension), the nitrogen and dry matter accumulation of vegetative organs of T₄ treatment (30% basal N fertilizer + 30% N fertilizer in vine extension + 40% N fertilizer in fruiting) and T₆ treatment (100% basal N fertilizer + NAM) were reduced significantly, but the nitrogen and dry matter accumulation of fruit were increased significantly in the flushing period. The nitrogen transportation ratio and nitrogen contribution ratio of T₄ were 33.6% and 12.0%, respectively. Compared to T₁, the nitrogen harvest index, nitrogen fertilizer partial factor productivity and nitrogen fertilizer recovery efficiency of T₄ and T₆ treatments increased by 14.1% and 12.7%, 11.6% and 12.5%, 5.3% and 8.7%, respectively, and yield of watermelon increased by 11.6% and 12.5%, the soluble sugar, effective acid, the ratio of sugar and acid, Vc content increased by 16.5% and 11.7%, 4.5% and 2.8%, 19.4% and 13.4%，35.6% and 19.0%, respectively. Therefore, T₄ and T₆ treatments were the optimal nitrogen fertilizer management mode which could not only achieve high yield and quality but also obtain high nitrogen fertilizer use efficiency in sand field. T₆ treatment was the best nitrogen fertilizer management mode considering reduction of fertilizing labor intensity and extending service time of gravelmulched field.


 

Effects of short-term continuous lighting with LED lamps and nitrogen nutrition conditions on quality of hydroponically grown purple lettuce.

YU Yi, YANG Qi-chang, LIU Wen-ke

2015, 26(11):  3361-3366. 

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Purple lettuce was grown hydroponically under six different nitrogen nutrition conditions, with NO₃^--N:NH₄⁺-N at 1:0, 4:1 and 1:1 combined with nitrogen application levels of 10 and 15 mmol·L^-1, for 25 days in solar greenhouse, then treated with shortterm continuous lighting (SCL) before harvest to study the changes in contents of nutrients and analyze the effects of nitrogen nutrition conditions on the changes. Results showed that the shoot dry mass of all six nitrogen nutrition conditions were significantly improved under SCL treatment,  by 35.1% at least, and the root dry mass increased greatly except for NO₃^--N:NH₄⁺-N 1:1 combined with nitrogen application level 15 mmol·L^-1 treatment and NO₃^--N:NH₄⁺-N 1:0 combined with nitrogen application level 10 mmol·L^-1 treatment. The relative contents of total phenols and flavonoid of different nitrogen nutrition conditions turned significantly different after treatment with SCL. The relative contents of total phenols and flavonoid were enhanced with the improvement of ammonium nitrogen ratio, while the relative content of anthocyanin increased and then decreased with the improvement of ammonium nitrogen ratio. The lighting treatment reduced the nitrate content of leaf blade of all six nitrogen nutrition conditions remarkably  by 23.2% at least. The contents of ascorbic acid, soluble sugar and soluble protein rose significantly under SCL treatments. The study showed that the reduction of nitrate content speeded up with the enhancement of nitrogen application level and ammonium nitrogen ratio, and the advancement of ascorbic acid content slowed down with the increasing nitrogen application level. The soluble sugar improvement speed increased with the increasing ammonium nitrogen ratio, and SCL lifted the dry mass of the lettuce greatly. The results showed that SCL with LED lamps improved significantly the dry matter of lettuce under different nitrogen nutrition conditions, reduced the nitrate content and increased the ascorbic acid, soluble sugar and soluble protein contents greatly. In addition, nitrogen nutrition conditions affected the effectiveness of shortterm continuous lighting on quality improvement rate of hydroponic lettuce remarkably.

Difference of potassium absorption characters and mechanism of tobacco in genotypes.

HE Bing1,2, HAN Zhu-jun1, XUE Gang1, XING Xue-xia1, XU Xiao-jing1, XU Shi-xiao1, ZHANG Xiao-quan1, YANG Tie-zhao1

2015, 26(11):  3367-3372. 

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Tabacco (Nicotiana tabacum) has a relatively high requirement for potassium (K). The difference in root characteristics and ability to release K from minerals of fluecured tobacco in four genotypes ND202, NC628, G28 and NC628×ND202 were analyzed. The results showed that the more available K released from minerals by roots, the more K would be accumulated by plants. ND202, which was Kenriched genotype, had well developed root system and was easily influenced by K content in the environment. Compared with ND202, NC628 significantly enhanced the effectiveness of K in substrate by releasing K from minerals, though the ability to absorb K was weak. Moreover, the hybrid of NC628×ND202 had a higher ability to release K and to tolerate lowlevel K than maternal parent. It was higher in dry matter accumulation and K enrichment than male parent. So hybridization had the utility value in highK variety cultivation. These results provided evidence that parents should have the ability to enhance available K from soil besides the high combining ability for breeding the highK variety.

Variation characteristics of soil carbon sequestration under long-term different fertilization in red paddy soil.

HUANG Jing1,2,3, ZHANG Yang-zhu2, GAO Ju-sheng1,3, ZHANG Wen-ju1, LIU Shu-jun1,3

2015, 26(11):  3373-3380. 

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The objective of this study was to clarify the changes of soil organic carbon （SOC） content, the saturation capacity of soil carbon sequestration and its cooperation with carbon input (crop source and organic fertilizer source carbon) under longterm (1982-2012) different fertilization in red paddy soil. The results showed that fertilization could increase SOC content. The SOC content of all the fertilization treatments demonstrated a trend of stabilization after applying fertilizer for 30 years. The SOC content in the treatments applying organic manure with mineral fertilizers was between 21.02 and 21.24 g·kg^-1, and the increase rate ranged from 0.41 to 0.59 g·kg^-1·a^-1. The SOC content in the treatments applying mineral fertilizers only was 15.48 g·kg^-1. The average soil carbon sequestration in the treatments that applied organic manure with mineral fertilizers ranged from 43.61 to 48.43 t C·hm^-2, and the average SOC storage over the years in these treatments was significantly greater than those applying mineral fertilizers only. There was an exponentially positive correlation between C sequestration efficiency and annual average organic C input. It must input exogenous organic carbon at least at 0.12 t C·hm^-2·a^-1 to maintain the balance of soil organic carbon under the experimental conditions.

Irrigation scheduling with a 20 cm standard pan for drip-irrigated cucumber grown in solar greenhouse in the North China Plain.

GONG Xue-wen1, SUN Jing-sheng1, LIU Hao1, ZHANG Hao1, WU Xiao-lei1, SUN Yu-hong2

2015, 26(11):  3381-3388. 

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An experiment was conducted in 2013 and 2014 at the Xinxiang Comprehensive Experimental Station, Chinese Academy of Agriculture Sciences. Water amount was estimated with  the E_p-20 and pan coefficient. Responses of cucumber evapotranspiration (ET), yield, quality and water use efficiency (WUE) to different drip irrigation amounts  (K_cp1: 0.25; K_cp2: 0.5; K_cp3: 0.75; K_cp4: 1.0; K_cp5: 1.25) were investigated. The possibility of developing drip irrigation scheduling using the 20 cm pan was also discussed. Results showed that the seasonal evapotranspiration of cucumber ranged between 129 and 314 mm, and the water consumption generally increased with the increase in drip irrigation water amount. There was no significance difference in cucumber yield between the treatments with K_cp >0.75, and the responses of mean fruit mass, number and length to water amount had a threshold value (0.75E_p-20). Regarding the fruit quality, the contents of total soluble solids, vitamin C and soluble sugar slightly decreased with increasing the irrigation water amount, while the soluble protein content varied in order as: K_cp2＞K_cp3＞K_cp4＞K_cp1＞K_cp5. There was a significant positive correlation (P<0.01) between the pan evaporation and the reference crop evapotranspiration estimated based on a modified PenmanMonteith equation. In a conclusion, the drip water amount calculated with K_cp of 0.75 and the 20 cm pan were easy and feasible for cucumber cultivation in solar greenhouse in the North China Plain.

Effects of different barnyardgrass species on grain yield of rice and their physiological characteristics under alternate wetting and drying irrigation.

ZHANG Zi-chang, LI Yong-feng, YANG Xia, GU Tao, LI Gui

2015, 26(11):  3389-3397. 

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In order to investigate the influence of different barnyardgrass species on rice yield and physiological characteristics of rice, two rice cultivars, Liangyoupeijiu (an indica hybrid cultivar) and Nanjing 9108 (a japonica cultivar), were employed to coculture with four barnyardgrass species during the period from transplanting to maturity under alternate wetting and moderate drying irrigation condition. The treatments were separately designed as follow: weed free (control), rice with Echinochloa crusgalli var. mitis (T₁), rice with E. crusgalli (T₂), rice with E. crusgali var. zelayensis (T₃) and rice with E. colonum (T₄). The results showed that T₁, T₂,T₃ and T₄ treatments reduced the Liangyoupeijiu yield by 13.8%, 10.6%, 23.8% and 0.5%, but the corresponding yield loss of Nanjing 9108 could reach up to 45.5%, 36.9%, 60.7% and 15.1%, respectively. The results above showed that T₁, T₂ and T₃ treatments all significantly reduced grain yield, and T₄ treatment only reduced grain yield for Nanjing 9108 but not for Liangyoupeijiu. All treatments  elevated malondialehyde contents of rice leaf, but the activities of peroxidase, catalase, superoxide dimutase, dry matter accumulation in maturity stage, root oxidation activities and contents of indole-3-acetic acid as well as zeatin+zeatin riboside in roots during rice grain filling stage were all decreased. The influence degree of four barnyardgrass against physiological indices of rice had the order of T₃>T₁>T₂>T₄. It showed that the reductions in  enzyme activities of antioxidant system, root oxidation activities, contents of indole-3-acetic acid, zeatin+zeatin riboside during grain filling stage and accumulation of dry matter in maturity as well as increase in contents of malondialehyde of rice during grain filling stage might be important reasons for grain yield reduction when grew with barnyardgrass.

 

Variability of soil water soluble organic carbon content and its response to temperature change in green spaces along urbantorural gradient of Nanchang, China.

LI Pei-qing, FANG Xiang-min, CHEN Fu-sheng, WANG Fang-chao, YU Jin-rong, WAN Song-ze, LI Zu-yao

2015, 26(11):  3398-3404. 

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Topsoil of green space including typical forest, shrub and grassland were collected to measure their water soluble organic carbon (WSOC) before and after incubation of 30 days at 5, 15, 25, 35 and, 45 ℃. The results showed the average values of WSOC were higher in urban than in rural green spaces, but the percentage of WSOC to total organic carbon (TOC) showed an opposite trend. No significant changes were found among the three green space types in WSOC and WSOC/TOC. Response of WSOC in green space to incubation temperature was generally highest in urban sites, followed by suburban sites, and lowest in rural sites at the incubation temperature of 5 ℃, but showed an opposite trend at the temperature of 45 ℃. Response coefficient of WSOC to temperature change was lower in forest and shrub than in grassland, but increased along the urbanrural gradient. Further analysis showed that WSOC positively correlated with TOC, total nitrogen and available phosphorus, and the response coefficient of WSOC to temperature change negatively correlated with available phosphorus. In summary, exogenous substances input might lead to the accumulation of WSOC in urban green space, however, urban environment was helpful to maintain the stability of WSOC, which might be due to the enrichment of available phosphorus in urban sites.

Vertical temperature distribution and its forecast for two tree structures of apple orchard during the blooming period in the Loess Plateau.

QU Zhen-jiang1, SHANG Xiao-ning2, WANG Jing-hong1, LIANG Yi1, GAO Feng1, YANG Fang3

2015, 26(11):  3405-3412. 

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Temperature is the most sensitive environment factor for the blooming period of apple. Temperatures at different levels were measured by automatic microclimatic gradient system in the blooming periods from 2011 to 2014, in two Fuji apple orchards with two different tree ages and structures \[small canopy open center shape (SMCOCS) and freedom spindle shape (FSS)\], respectively, which were typical in the Loess Plateau. Variations of the temperature gradient in both canopy and tree body were analyzed in sunny, overcast, cloudy, and rainy weather conditions, and a predicting model was established that could predict the temperature of the canopy (TL) according to the temperature observed in nearby meteorological station (TM). The results showed that the vertical distribution of canopy temperature and its difference to the outside of orchard was mainly due to the tree structure, rather than the weather condition. The average temperature and daily minimum temperature increased while the daily maximum temperature and the diurnal temperature range decreased from the bottom to the upper of the canopy. For SMCOCS, the diurnal temperature range reached its peak under the canopy in the clear days, and the diurnal temperature range was less than that for FSS in the middle and upper canopy in cloudy or overcast conditions. The daily variation of temperature difference between inside and outside the orchard behaved as a single peakvalleypeak for FSS but as a single peak for SMCOCS. The minimum temperature outside the orchard was closer to that in the middle of canopy, but higher than that in the bottom of the canopy. For SMCOCS, the minimum temperature in the bottom of its canopy was rather lower than that in the orchard outside, especially in cloudy or overcast day, while in the middle or upper canopy, the minimum temperature difference with the orchard outside was smaller than that for the FSS. The linear model was found to be able to predict the TL with absolute errors below 1 ℃, and the best prediction was found for the FSS in rainy days.

A site index model for Larix principisrupprechtii plantation in Saihanba, north China.

WANG Dong-zhi1, ZHANG Dong-yan1,2, JIANG Feng-ling3, BAI Ye4, ZHANG Zhi-dong1, HUANG Xuan-rui1

2015, 26(11):  3413-3420. 

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It is often difficult to estimate site indices for different types of plantation by using an ordinary site index model. The objective of this paper was to establish a site index model for plantations in varied site conditions, and assess the site qualities. In this study, a nonlinear mixed site index model was constructed based on data from the second class forest resources inventory and 173 temporary sample plots. The results showed that the main limiting factors for height growth of Larix principisrupprechtii were elevation, slope, soil thickness and soil type. A linear regression model was constructed for the main constraining site factors and dominant tree height, with the coefficient of determination being 0.912, and  the baseline age of  Larix principisrupprechtii determined as 20 years. The nonlinear mixed site index model parameters for the main site types were estimated (R² >0.85, the error between the predicted value and the actual value was in the range of -0.43 to 0.45, with an average root mean squared error (RMSE) in the range of 0.907 to 1.148). The estimation error between the predicted value and the actual value of dominant tree height for the main site types was in the confidence interval of \[-0.95, 0.95\]. The site quality of the high altitude-shady-sandy loam-medium soil layer was the highest and that of low altitude-sunny-sandy loammedium soil layer was the lowest, while the other two sites were moderate.

Estimation of light-use efficiency of China’s midsubtropical planted coniferous forest based on flux measurements and spectral observations.

CHEN Die-cong1,2, WANG Shao-qiang1, HUANG Kun1,2, ZHOU Lei1, YU Quan-zhou1,2, WANG Hui-min1,3, SUN Lei-gang4

2015, 26(11):  3421-3432. 

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The photochemical reflectance index (PRI) calculated from spectral reflectance has universally become a proxy for the lightuse efficiency (LUE), which significantly improves the LUEbased estimation of ecosystem gross primary productivity on a large scale through upscaling. In this study, we observed the vegetation spectral reflectance of a planted subtropical coniferous forest from the top of a flux tower at Qianyanzhou Station, one of the ChinaFLUX sites, in September and December 2013, and simultaneously measured CO₂ flux and meteorological variables for correlation and regression analysis. Results showed that PRI had a better correlation with LUE (R²=0.20, P<0.001) than that of normalized difference vegetation index (NDVI), i.e., PRI was preferred in LUE retrieval. During the whole observation period, PRI and soil water content (SWC)based bivariate regression model correlated well with LUE (R₂=0.29, P<0.001 and R²=0.30, P<0.01 for daytime and midday observation, respectively), but in autumn the bivariate regression model of PRI and vapor pressure deficit (VPD) had a higher correlation with LUE (R²=0.448, P<0.001) for midday observation, which showed that environmental factors, i.e., SWC and VPD, had a potential in improving the LUE retrieval from PRI, but the choice of appropriate environmental factors depended on season.

Estimation of Hunan forest carbon density based on spectral mixture analysis of MODIS data.

YAN En-ping1, LIN Hui1, WANG Guang-xing1,2, CHEN Zhen-xiong3

2015, 26(11):  3433-3442. 

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With the fast development of remote sensing technology, combining forest inventory sample plot data and remotely sensed images has become a widely used method to map forest carbon density. However, the existence of mixed pixels often impedes the improvement of forest carbon density mapping, especially when low spatial resolution images such as MODIS are used. In this study, MODIS images and national forest inventory sample plot data were used to conduct the study of estimation for forest carbon density. Linear spectral mixture analysis with and without constraint, and nonlinear spectral mixture analysis were compared to derive the fractions of different land use and land cover (LULC) types. Then sequential Gaussian co-simulation algorithm with and without the fraction images from spectral mixture analyses were employed to estimate forest carbon density of Hunan Province. Results showed that 1) Linear spectral mixture analysis with constraint, leading to a mean RMSE of 0.002, more accurately estimated the fractions of LULC types than linear spectral and nonlinear spectral mixture analyses; 2) Integrating spectral mixture analysis model and sequential Gaussian cosimulation algorithm increased the estimation accuracy of forest carbon density to 81.5% from 74.1%, and decreased the RMSE to 5.18 from 7.26; and 3) The mean value of forest carbon density for the province was 30.06 t·hm^-2, ranging from 0.00 to 67.35 t·hm^-2. This implied that the spectral mixture analysis provided a great potential to increase the estimation accuracy of forest carbon density on regional and global level.

Difference between carbon storage of burned area under different restorations in Greater Xing’an Mountains, Northeast China.

XIN Ying, ZOU Meng-ling, ZHAO Yu-sen

2015, 26(11):  3443-3450. 

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In order to explore forest restoration approach effect on carbon storage of severely burned area in Greater Xing’an Mountains, the carbon contents of tree, shrub, herb and litter from two plantations (Larix gmelinii and Pinus sylvestris var. mongolica) and natural secondary forest were determined, respectively, by using dry combustion method. The biomass of each component was obtained to estimate the distribution characterization of forest vegetation carbon storage by combing whole harvest method with average standard wood method. The results showed that, for both plantations and secondary forest, the average carbon content of shrub was higher than that of arbor and herb. In the L. gmelinii plantation, the average carbon contents of shrub, litter, arbor and herb were 45.8%, 45.3%, 44.4% and 33.6%, respectively. The average carbon content of shrub and arbor was more than 50% in P. sylvestris var. mongolica plantation, while that of arbor, shrub and litter was about 42% for the secondary forest. The biomass of arbor was higher than shrub and herb. In L. gmelinii plantation, the total biomass of vegetation and litter was 123.90 t·hm^-2, which was significantly higher than that of P. sylvestris var. mongolica plantation and secondary forest. The carbon storage of vegetation in L. gmelinii plantation was 50.97 t·hm^-2, among which the arbor was 49.87 t·hm^-2, accounting for 97.8% of the total carbon storage in forest vegetation, while the proportion of herb carbon storage only occupied 0.02%. The total carbon storage of plantations was higher than that of the secondary forest, suggesting a stronger capacity of carbon sink through artificial restoration on severely burned area in Greater Xing’an Mountains during this period.

Quantification of crop residue burned areas based on burning  indices using Landsat 8 image.

MA Jian-hang1,2, SONG Kai-shan1, WEN Zhi-dan1, SHAO Tian-tian1,2, LI Bo-nan1, QI Cai3

2015, 26(11):  3451-3456. 

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Crop residue burning leads to atmospheric pollution and is an enormous waste of crop residue resource. Crop residue burning can be monitored timely in large regions as the fire points can be recognized through remotely sensed image via thermal infrared bands. However, the area, the detailed distribution pattern and especially the severity of the burning areas cannot be derived only by the thermal remote sensing approach. The burning index, which was calculated with two or more spectral bands at where the burned and unburned areas have distinct spectral characteristics, is widely used in the forest fire investigation. However its potential application for crop residue burning evaluation has not been explored. With two Landsat 8 images that cover a part of the Songnen Plain, three burning indices, i.e., the normalized burned ratio (NBR), the normalized burned ratio incorporating the thermal band (NBRT), and the burned area index (BAI), were used to classify the crop residue burned and unburned areas. The overall classification accuracies were 91.9%, 92.3%, and 87.8%, respectively. The correlation analysis between the indices and the crop residue coverage indicated that the NBR and NBRT were positively  correlated with the crop residue coverage (R²=0.73 and 0.64, respectively) with linear regression models, while the BAI was exponentially correlated with the crop residue coverage (R²=0.68). The results indicated that the use of burning indices in crop residue burning monitoring could quantify crop residue burning severity and provide valuable data for evaluating atmospheric pollution.

Spatio-temporal variability of habitat quality in BeijingTianjinHebei Area based on land use change.

WU Jian-sheng1,2, CAO Qi-wen1, SHI Shu-qin3, HUANG Xiu-lan1, LU Zhi-qiang1

2015, 26(11):  3457-3466. 

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Land use change is the core content of global change. To achieve sustainable land use planning, it is necessary to evaluate the habitat quality pattern and its spatiotemporal variation resulted from land use change, which can provide basis for the formulation of land management policy. Based on the analysis of land use change from 2000 to 2010, this study investigated the spatio-temporal variation of habitat quality pattern of BeijingTianjinHebei Area. We used the watershed profile sampling points and spatial autocorrelation analysis based on watershed subdivision. The results showed that the main land use change types from 2000 to 2010 in this area included the transition from cultivated land to construction land, the transition between forest and grassland, and the transition from water bodies to cultivated land. This land use/cover change process led to the decrease of heterogeneity of landscape structure and increase of fragmentation. The overall spatial pattern of habitat quality was that southeast and south areas were relatively lower, while north and west areas were relatively higher. The analysis based on watershed profile showed that the habitat quality of each watershed presented significant difference in each part. Habitat quality of most sampling points degraded in a way, while some improved compared with 2000. In general, the habitat quality of the bottom part of Luanhe River basin, the medium part of BaiChaobaiChaobaixin River basin, the medium and the bottom part of Yongding River basin and medium part of LaozhangFudongpaiBeipai River basin were poor and volatile, while other parts were relatively good. There was a decreasing agglomeration characteristic of distribution of habitat quality in BeijingTianjinHebei Area under the disturbance of human activities. Areas of high habitat quality in 2000 were mainly located in Luanhe River basin and top part of Baihe basin. Areas of low habitat quality were mainly located in medium and bottom part of Yongding River basin and some parts of Chaobai River basin. However, the areas of high habitat quality and areas with low habitat quality of 2010 had both expanded towards southwest.

Spatiotemporal variations of natural wetland CH₄ emissions over China under future climate change.

LIU Jian-gong1, ZHU Qiu-an1, SHEN Yan2, YANG Yan-zheng1, LUO Yun-peng1, PENG Chang-hui1

2015, 26(11):  3467-3474. 

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Based on a new processbased model, TRIPLEX-GHG, this paper analyzed the spatiotemporal variations of natural wetland CH₄ emissions over China under different future climate change scenarios. When natural wetland distributions were fixed, the amount of CH₄ emissions from natural wetland ecosystem over China would increase by 32.0%, 55.3% and 90.8% by the end of 21st century under three representative concentration pathways (RCPs) scenarios, RCP2.6, RCP4.5 and RCP8.5, respectively, compared with the current level. Southern China would have higher CH₄ emissions compared to that from central and northern China. Besides, there would be relatively low emission fluxes in western China while relatively high emission fluxes in eastern China. Spatially, the areas with relatively high CH₄ emission fluxes would be concentrated in the middlelower reaches of the Yangtze River, the Northeast and the coasts of the Pearl River. In the future, most natural wetlands would emit more CH₄ for RCP4.5 and RCP8.5 than that of 2005. However, under RCP2.6 scenario, the increasing trend would be curbed and CH₄ emissions (especially from the QinghaiTibet Plateau) begin to decrease in the late 21st century.

Regulation of four typical scenic recreational plantations to stand PM_2.5 concentration in Beijing, China.

ZHANG Zhi-dan1, CAO Zhi-guo2, JIA Li-ming1

2015, 26(11):  3475-3481. 

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To study the variation of PM_2.5 concentration in scenic recreational plantations and its response to meteorological factors, and to analyze the regulation effect of different stands on PM_2.5 concentration, in the summer, autumn and winter of 2013, PM_2.5 concentration and relevant meteorological factors in four typical scenic recreational plantations (Pinus armandii-Ginkgo biloba mixed plantation, Populus tomentosa-Fraxinus chinensi mixed plantation, Populus tomentosa pure plantation, multiple-species-layered mixed plantation) were simultaneously monitored, in Beijing Olympic Forest Park (the observation was conducted continuously for 28 days). The results showed that the daily variation of PM_2.5 concentration in the four stands didn’t represent a unified pattern at different air pollution levels, but were basically consistent at the same pollution level. When the wind force was 0-2 grade, there was no significant difference among daily average PM_2.5 concentrations \[the average PM_2.5concentration during the observation period (9:00—15:00)\] in the four stands at each pollution level. Stand PM_2.5 concentration was positively correlated to air relative humidity (P<0.01), negatively correlated with air temperature (P<0.05), but uncorrelated with wind speed. Changed percentage of stand PM_2.5 concentration compared to the space varied between -21.4% and 33.2%, and it was negatively correlated with air relative humidity (P<0.05), but not correlated with the wind speed and air temperature. The regulation effects of the four stands on PM_2.5 concentration included both increasing and decreasing effects, and in this study, the critical value of air relative humidity was 67% when this regulation shifted.

Effects of mowing and grazing on soil nutrients and soil microbes in rhizosphere and bulk soil of Stipa grandis in a typical steppe.

HU Jing1,2, HOU Xiang-yang1, WANG Zhen1, DING Yong1, LI Xi-liang1,2, LI Ping1， JI Lei1

2015, 26(11):  3482-3488. 

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This study conducted experiments using Stipa grandis, the dominant species of the typical steppe in Inner Mongolia. The research explored the different effects of mowing and grazing on organic carbon, total nitrogen, available nitrogen, total phosphorus and available phosphorus in rhizosphere and bulk soil. The results showed that: Both mowing and grazing inhibited assemble and storage capacity of rhizosphere, and decreased the organic carbon, total nitrogen, and available nitrogen contents in rhizosphere soil. The rhizosphere effect on total phosphorus in soil was found to be insignificant because of its high immobility. Available phosphorus in soil was distributed heterogeneously. Available soil phosphorus under mowing and grazing changed but the difference was not significant between rhizosphere and bulk soil. Grazing drastically reduced the number of soil microbes. The availability of soil nutrients was significantly correlated with soil microbial numbers. The status of soil nutrients could be more closely aligned with the change in bacteria and fungi. Grazing brought about greater soil nutrient loss and soil microbe loss than did mowing.

 

Characteristics of soil nematode community of different agricultural areas in Jiangsu Province, China.

JIAO Jia-guo, LIU Bei-bei, MAO Miao, YE Cheng-long, YU Li, HU Feng, LI Hui-xin

2015, 26(11):  3489-3496. 

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This paper investigated the genus diversity of soil nematodes of different agricultural areas in Jiangsu Province, analyzed the relationship between soil nematodes and soil environmental factors, and discussed the roles of soil nematodes as biological indicators of soil health. The results showed that, a total of 41 nematode genera were found in all six agricultural areas, belonging to 19 families, 7 orders, 2 classes. The numbers and community compositions of nematodes were obviously influenced by soil texture, fertilization and tillage practices. In all six agricultural areas, the numbers of nematodes in coastal agricultural area (400 individuals per 100 g dry soil) were significantly larger than that in Xuhuai, Ningzhenyang, and riverside agricultural areas. While the smallest number of nematodes was found in Yanjiang agricultural area (232 individuals per 100 g dry soil), which might be due to the differences in soil texture, annual rainfall and annual air temperature and other factors. The dominant genera of nematodes were similar in the adjacent agricultural areas. Correlation analysis showed that there was a significant positive correlation between the number of soil nematodes and levels of soil nutrients (soil organic matter, total nitrogen, available nitrogen, available potassium and available phosphorus). Redundancy analysis (RDA) indicated the total nitrogen, available potassium and pH obviously affected some soil nematode genera. The analysis of spatial distribution characteristics of soil nematode community in farmland of Jiangsu Province could provide data for health assessment of agricultural ecosystems.

Synergistion mechanism of exogenous Ca²⁺ to SAinduced resistance to Botrytis cinerea in tomato.

LI Lin-lin1,2, LI Tian-lai2, JIANG Guo-bin1, JIN Hua1, ZOU Ji-xiang1

2015, 26(11):  3497-3502. 

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In this study, we investigated the effect of exogenous calcium and salicylic acid (SA) on Botrytis cinerea resistance in tomato seedlings. We treated a tomato strain susceptible to Botrytis cinerea with foliar spraying of water, SA, SA+CaCl₂ and SA+EGTA (Ca²⁺ chelating agent) for one to five days. During the treatment, leaves were collected to analyze the reactive oxygen species (ROS) content, phenylalanine ammonia lyase (PAL) activity, chintase and β-1,3-glucanase levels, and the expression of pathogenesis related protein 1, 2, 3 (PR1, PR2, PR3). Three days after infection, the disease index was
74.8 in control plants, and 46.9, 38.5 and 70.3 in SA, SA+Ca and SA+EGTA 〖JP〗treated plants, respectively. SA treatment significantly increased ROS leaf accumulation, and activities of PAL, chintase and β-1,3-glucanase. These values were further enhanced in SA+Ca treated plants, but decreased in SA+EGTA treated plants. Application of SA significantly increased the expression levels of PR1, PR2a and PR3b, which were further elevated by the combination treatment with Ca²⁺. These effects were counteracted by the combination treatment of SA and EGTA. The transcription levels of PR2b and PR3a were upregulated by 1-2 folds, and PR1, 2a and 3b by 2-5 folds in SA and SA+Catreated plants relative to control. These data suggested that application of Ca²⁺ could synergistically increase SAinduced resistance to B. cinerea. The resistance was associated with ROS accumulation, therefore the increase in resistance might be through ROS ability to increase the activity of defenserelated enzymes and expression levels of PR1, PR2a and PR3b.

Adaptability of Helianthus annuus seedlings to crude oil pollution in soil and its improvement measures under salinization stress.

ZHANG Jing-lei, CI Hua-cong, HE Xing-dong, LIANG Yu-ting, ZHAO Xuan, SUN Hui-ting, XIE Hong-tao

2015, 26(11):  3503-3508. 

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To explore the adaptability of plant under salt stress to crude oil pollution of soil and improvement measures, a pot experiment of Helianthus annuus seedlings was conducted using orthogonal experiment method with crude oilsodium chloridedesulfurization gypsum and cinderzeolitedesulfurization gypsumsawdust. The results showed that, with the increase of soil crude oil concentration, the relative growth rate (RGR) of plant height, RGR of aboveground biomass and root N:P ratios of H. annuus seedlings decreased significantly, while the activity of SOD and CAT increased at first and then decreased significantly. The RGR of plant height and aboveground biomass significantly increased (P<0.05), while the activity of SOD decreased gradually with the increase of the volume fraction of sawdust, indicating that sawdust had the most significant effect in comparison with cinder, zeolite, desulfurization gypsum under salinization condition. The crude oil pollution of soil could decrease the relative growth rate of H. annuus seedling, and sawdust could reduce the influence of crude oil pollution on plant growth under salt stress.

Shrimp community structure and its relationships with environmental factors in the Yellow Sea in summer.

PANG Zhi-wei, LI Xian-sen, YING Yi-ping, WU Qiang, LUAN Qing-shan

2015, 26(11):  3509-3515. 

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Based on the data collected from the bottom trawl survey in Yellow Sea, August, 2014, the community structure of shrimp assemblage and its relationships with environmental factors in summer was examined by using index of relative importance, ecological diversity indices and multivariate statistical analysis. A total of 20 shrimp species were captured, belonging to 3 orders, 10 families, 16 genera. The relative abundance of shrimp of all stations ranged from 13 to 45047 g·h^-1 and its mean value was 6838 g·h^-1. The dominant species was Crangon affinis, and the common species was Eualus sinensis. The rare species were Metapenaeopsis dalei, Palaemon gravieri and Oratosquilla oratoria. The ranges of Shannon diversity index (H), Pielou’s evenness index (J) and the Margalef’s species richness index (D) of all stations of the shrimp community structure were 0.007-1.538, 0.101-1.138 and 0.006-0.947, respectively, and the mean values of H, J and D were 0.391, 0.374 and 0.298, respectively. MDS and Cluster analyses revealed that two clusters of Group I named cold water mass group and Group II named coastal group, which were bounded by the 45 m isobaths, were identified for all the sampling stations. Significant difference was detected by ANOSIM analysis between Group I and Group II. BIOENV analysis indicated that bottom temperature and bottom salinity were the most important environmental factors for structuring the spatial distribution of the shrimp assemblage. Cold water mass group accounted for absolute advantage and Yellow Sea cold mass had a decisive influence on the distribution pattern of the shrimp community in the Yellow Sea in summer.

Cladocera in Bosten Lake: Community characteristics and driving factors.

QI Feng, MA Yan-wu, LI Hong, XIE Chun-gang, CHEN Peng, CHEN Mu-xia

2015, 26(11):  3516-3522. 

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Cladocera of 17 sampling locations in Bosten Lake were investigated 11 times from 2010 to 2013. Their community structure and succession dynamics were elaborated, and their responses to environment factors were analyzed. The results showed that a total of 14 species were identified and 3 of them were the dominant species. Compared with history data, species preferring oligotrophic conditions were decreasing or even disappeared, and species preferring eutrophic conditions had occupied the dominant position gradually. Spatial and temporal distribution of Cladocera densities changed greatly. Densities of the 17 sampling locations varied from 0-567.0 ind·L^-1 with an average of 30.0 ind·L^-1. Annual density of 2011 was the highest (82.5 ind·L^-1), and then decreased year by year. Horizontal distribution of Cladocera showed a significant difference, and it was higher in shallow water area along the coast than in deep water area in the center. Temperature was the main ecological factor affecting the Cladocera community. Species distribution changed with water depth, and Daphnia longispina was common in the deep water while Bosmina longirostris was common in shallow water. Food limitation and fish predation might be the important reason that caused the variation of community structure.

Assessment of ecosystem energy flow and carrying capacity of swimming crab enhancement in the Yellow River estuary and adjacent waters.

LIN Qun, WANG Jun, LI Zhong-yi, WU Qiang

2015, 26(11):  3523-3531. 

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Stock enhancement is increasingly proved to be an important measure of the fishery resources conservation, and the assessment of carrying capacity is the decisive factor of the effects of stock enhancement. Meanwhile, the variations in the energy flow patterns of releasing species and ecosystem were the basis for assessing carrying capacity of stock enhancement. So, in the present study, based on the survey data collected from the Yellow River estuary and adjacent waters during 2012-2013, three Ecopath massbalance models were established in June, August and October, and the variations in ecosystem energy flow in these months were analyzed, as well as the assessment of carrying capacity of swimming crab enhancement. The energy flow mainly concentrated on trophic level I-III in Yellow River estuary and adjacent waters, and was relatively less on trophic level IV or above. The system flow proportion on the trophic level I was the highest in June, and was the lowest in August. The highest system flow proportion on the trophic level II was found in August, and the lowest in June. The relative and absolute energy flow of swimming crab mainly concentrated on the trophic level III, and the mean trophic level of swimming crab among June, August and October were 3.28. Surplus production was relatively higher in Yellow River estuary and adjacent waters, the highest value was found in June, and the lowest value in August. The ratios of total primary production/total respiration (TPP/TR) were 5.49, 2.47 and 3.01 in June, August and October, respectively, and the ratios of total primary production/total biomass (TPP/B) were 47.61, 33.30 and 29.78, respectively. Combined with the low Finn’s cycling index (FCI:0.03-0.06), these changes indicated that the Yellow River estuary ecosystem was at an early development stage with higher vulnerability. The energy conversion efficiency of system was from 7.3% to 11.5%, the mean trophic levels of the catch were 3.23, 2.97 and 2.82 in June, August and October, respectively. The highest gross efficiency of the fishery was found in August, and the lowest in June. Finally, based on the Ecopath model in August survey, the preliminarily assessed carrying capacity of swimming crab was 1.5115 t·km^-2 in Yellow River estuary and adjacent waters.

 

Effects and mechanism of freeze-thawing cycles on key processes of nitrogen cycle in terrestrial ecosystem.

WANG Li-qin1,2,3, QI Yu-chun1,2, DONG Yun-she1,2, PENG Qin1,2, GUO Shu-fang1,2,3, HE Yun-long1,2,3, YAN Zhong-qing1,2,3

2015, 26(11):  3532-3544. 

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As a widespread natural phenomenon in the soil of middle and high latitude as well as high altitude, freezethawing cycles have a great influence on the nitrogen cycle of terrestrial ecosystem in nongrowing season. Freezethawing cycles can alter the physicochemical and biological properties of the soil, which thereby affect the migration and transformation of soil nitrogen. The impacts of freezethawing cycles on key processes of nitrogen cycle in terrestrial ecosystem found in available studies remain inconsistent, the mechanism is still not clear, and the research methods also need to be further explored and innovated. So it is necessary to sum up and analyze the existing achievements in order to better understand the processes of soil nitrogen cycle subjected to freezethawing cycles. This paper reviewed the research progress in China and abroad about the effects and mechanisms of freezethawing cycles on key processes of nitrogen cycle in terrestrial ecosystem, including mineralization, immobilization, nitrification and denitrification, N leakage and gaseous loss, and analyzed the deficiencies of extant research. The possible key research topics that should be urgently paid more attention to in the future were also discussed.

Strategy of selecting 16S rRNA hypervariable regions for matagenome-phylogenetic marker genes based analysis.

ZHANG Jun-yi1,2, ZHU Bing-chuan1, XU Chao1, DING Xiao2, LI Jun-feng3, ZHANG Xue-gong3,LU Zu-hong2,4

2015, 26(11):  3545-3553. 

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The advent of next generation sequencing technology enables parallel analysis of the whole microbial community from multiple samples. Particularly, sequencing 16S rRNA hypervariable tags has become the most efficient and costeffective method for assessing microbial diversity. Due to its short read length of the 2ndgeneration sequencing methods that cannot cover the full 16S rRNA genomic region, specific hypervariable regions or V-regions must be selected to act as the proxy. Over the past decade, selection of V-regions has not been consistent in assessing microbial diversity. Here we evaluated the current strategies of selecting 16S rRNA hypervariable regions for surveying microbial diversity. The environmental condition was considered as one of the important factors for selection of 16S rRNA hypervariable regions. We suggested that a pilot study to test different V-regions is required in bacterial diversity studies based on 16S rRNA genes.

Emissions of methyl halides from coastal salt marshes: A review.

XIE Wen-xia1, ZHAO Quan-sheng1, CUI Yu-qian1, DU Hui-na1, YE Si-yuan2

2015, 26(11):  3554-3560. 

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Methyl halides are the major carrier of halogens in the atmosphere, and they play an important role in tropospheric and stratospheric ozone depletion. Meanwhile, methyl halides can act as greenhouse gases in the atmosphere, and they are also environmentally significant because of their toxicity. Coastal salt marshes, the important intertidal ecosystems at the landocean interface, have been considered to be a large potential natural source of methyl halides. In this paper, the research status of the natural source or sink of methyl halides, the mechanisms of their emission from coastal salt marshes and affecting factors were summarized. In view of this, the following research fields need to be strengthened in the future: 1) Long timescale and large regionrange researches about the emission of methyl halides and the evaluation of their source and sink function, 2) Accurate quantification of contribution rates of different plant species and various biological types to fluxes of methyl halides, 3) Further researches on effects of the tidal fluctuation process and flooding duration on methyl halides emission, 4) Effects of the global change and human activities on methyl halides emission.

Archival tags and geolocation methods for marine animals: A review.

ZHANG Tian-feng 1,2, FAN Wei1, DAI Yang1

2015, 26(11):  3561-3566. 

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Archival tags, a group of data storable electronic tags, are widely used as strong tools for obtaining long term and large scale activity information of marine animals, specifically highly migratory oceanic fishes, and corresponding environmental data. Though retrieving tags is an indispensable step for obtaining data, which is a shortage of archival tags, a series of achievements have been made on marine animals by using archival tags since the 1990s. With the appearance of popup satellite tag, which solved the problem of data retrieving and was fully independent of the fishing, both breadth and depth of marine animals’ studies are extended by the end of the 1990s. Geolocation based on light intensity is the key to estimate marine animals’ movement and has achieved some progress in the past 20 years. However, the accuracy of geolocation for latitude is not high enough, and there is still much room for improvement. To date, most geolocation methods that use ambient daylight involve identifying the times when the sun is at a precisely known zenith angle (e.g., sunrise and sunset). The problem of estimating longitude has been proved easy to solve, but accurate latitude estimates remain elusive. This paper mainly introduced two tags, i.e., archival tags and popup tags, and three geolocation methods, i.e., 1) the “fixed reference” method, 2) the “variable reference” method, and 3) the “reflection” method. We also presented a prospect analysis on archival tags and possible research direction of geolocation methods. We believed that miniaturization and multisensor integration are the trends for electronic tags while more environmental factors such as depth, SST (sea surface temperature) or magnetic field intensity, instead of single factor, as auxiliary parameters would be used for improving the geolocation accuracy in the future.