Table of Content

10 February 2018, Volume 37 Issue 2

Previous Issue    Next Issue

Litter stock and nutrient characteristics of decomposing litter layers in Maolan Karstprimary forest in different slope directions.

ZHAO Chang, LONG Jian, LI Juan, LIAO Hong-kai, LIU Ling-fei, ZHANG Ming-jiang, HUA jian

2018, 37(2):  296-303. 

Asbtract ( 487 )   PDF (611KB) ( 187 )  

In the present study, we selected forest floor litters from three slope directions inMaolan Karst primary forest to investigate the distribution characteristics of litter stock, nutrientcontents (C, N, P and K) and their release rates of different decomposing layers. The results showed that: (1) Total litter stock was higher in north slope (0.568 kg·m^-2) than that in south slope (0.504 kg·m^-2) and northeast slope (0.295 kg·m^-2). Litter stocks in different layers arranged in the order of fresh litter layer (layer L>fragmented litter layer (layer F) > fullydecomposed layer (layer Y); (2) The C and K contents in different decomposing layers were in the order of layer L>layer F>layer Y, whereas the N and P contents were followed by the order of layer Y> layer F> layer L. (3) Total storage of litter C, N and K was in the order of north slope>south slope>northeast slope, and total litter P storage was the highest in the south slope, followed by north slope, and then the northeast slope. (4) The litter nutrient storage in layer Laccounted for 37.1% to 64.2% of the total nutrient storage, showing a decrease trend with theincreases of decomposition degrees. The release rates of the nutrient elements in layers L and F were the highest in the north slope, followed by the northeast slope and the south slope.Moreover, the release rates of C and K were higher than that of N and P. Our results indicated that the slope direction had a great influence on the chemical properties and decomposition rate oflitters. In general, litters in the north slope decomposed rapidly and the cycling time of nutrient elements was shorter than that in other slopes in the Karst primary forest.

Effects of freezethaw cycles on soil microbial biomass carbon and carbon emissions from wetland soils, Northeast China.

ZHANG Chao-fan, SHENG Lian-xi, GONG Chao, HE Chun-guang, ZHANG Jing

2018, 37(2):  304-311. 

Asbtract ( 734 )   PDF (580KB) ( 179 )  

A laboratory experiment was conducted to assess the effects of the freezing thawingcycles (FTCs) on soil microbial biomass carbon (MBC), and CO₂ and CH₄ emissions from wetland soils in the continuous permafrost zone (TQ) and seasonally frozen region (JC) of Northeast China. Soil samples were incubated at different frost intensities \[+5 (control), -5, and -15 ℃\] for 12 h respectively, and then thawed at +5 ℃ for 12 h. These freezethaw cycles were repeated for 0, 1, 5, 10, and 15 times. The results showed that the CO₂ and CH₄ emission rates and MBC of two  types of soil decreased after the first freezethaw incubation, and presented an increase and then decrease pattern and then trended to be stable with the increases of cycling times. Compared with the control (5 ℃) and low frost intensity (-5 ℃) treatments, high frost intensity (-15 ℃) significantly promoted CO₂ and CH₄ emissions but did not significantly influence MBC. At -15 ℃, the cumulative CO₂ emissions from TQ soil reached 679.99 mg·kg^-1 after 15 FTCs, which was about 50% higher than that of JC soil (454.32 mg·kg^-1). The highest cumulative CH₄ emission from TQ soil was 334.49 μg·kg^-1 at -5 ℃ after 15 FTCs, while this value was 600.07 μg·kg^-1 at -15 ℃ for JC soil. The temperature sensitivities of methanogens might bedifferent between these two frozen soils during the freezingthawing cycles. Our results provide scientific data for the assessment of global climate change on soil carbon turnover in the mainpermafrost regions of Northeast China.

 

Effects of dryingwetting cycles on soil organic carbon mineralization along an elevation gradient in Wuyi Mountain.

HUANG Shi-de, YE Gong-fu, LIN Jie, RUAN Hong-hua, JIN Cang-shan, LI Yuan-yuan, CHEN Jie

2018, 37(2):  312-321. 

Asbtract ( 478 )   PDF (835KB) ( 162 )  

Drying wetting (DW) cycles have important influence on soil carbon mineralization, nutrient cycle, and microbial growth and metabolism. Soil samples (0-10 cm layer) were taken from three different elevations in Wuyi Mountain, and were incubated under temperature of 5, 15 and 25 ℃ in the laboratory, respectively. DW and constant water content (CW) treatments were set to examine the effects of dryingwetting on soil carbon mineralization. The results showed that, compared to CW treatment, carbon mineralization significantly decreased when the soil became dry. When the dry soils were rewetted, a flush of mineralized C was observed. Such pulse effect of rewetting gradually decreased with the increases of DW cycles. The cumulative soil carbonmineralization of DW treatment was significantly lower than that of CW treatment, indicating that the amount of pulse mineralized C in rewetting of dry soil was not enough to compensate for the reduction of mineralized C during the drought period. The temperature sensitivity (Q₁₀) in the DW treatment was significantly lower than that in the CW treatment. In DW treatment, the moisture sensitivity (k) increased with the elevation, indicating that soil mineralization was more dependent on moisture in high elevation than in low elevation. Microbial biomass carbon content of DW treatment was higher than that of CW treatment, while dissolved organic carbon content of cold and hot water extraction was lower than that of CW treatment.

Variation of  net ecosystem carbon flux in growing season and its driving factors in a poplar plantation from Hung-tse Lake wetland.

XU Yong-feng, JI Huai, HAN Jian-gang, XUE Tong-liang, ZHU Yong-li, LI Ping-ping

2018, 37(2):  322-331. 

Asbtract ( 459 )   PDF (1394KB) ( 209 )  

Fluctuations of water level in Hung-tse Lake are induced by the regional increasingirrigation demands and normalized water transfer with the operation of the SouthtoNorth water diversion project, with consequences on soil moisture and wetland vegetation. A poplar plantation in Hung-tse Lake wetland was selected to investigate the dynamics of CO₂ flux and its influencing factors during the growing season (April to September) using the system of eddy covariance in 2016. The results showed that a typical daily and monthly variation characterized the changes of net ecosystem CO₂ exchange (NEE) and environmental factors across the whole growing season. The monthly meanNEE showed a general “U” type curve with1758.10 g CO₂·m^-2 of accumulatedNEE, implying that the plantation was a carbon sink in the growing season. There was ahyperbolic relationship between the photosynthetically active radiation (PAR) and daytime netecosystem CO₂ exchange (NEE_d).PAR accounted for 34.3%-75.5% of the variation ofNEE_d in the growing season. A significant exponential function relationship between soil temperature (T_s) at 5 cm depth and nighttime net ecosystem CO₂ exchange (NEE_n) was found, andT_s explained38.9%-55.2% of the variation inNEE_n. Soil water content, net radiation (R_n) and vaporpressure deficit mainly dominated the daily variation of CO₂ flux, while the monthly variation of CO₂ flux was mainly affected by rainfall and soil moisture. Therefore, changes of soil moisture in the wetlands, affected by the fluctuations of water level in Hung-tse Lake, would potentiallyaffect ecosystem carbon sequestration.

 

Niche characteristics of understory herb layer in a mature Chinese fir plantation.

ZHENG Xiao-yang, ZHAO Chong, LIU Qing-qing, FENG Yu-chao, ZHU Chen-xi, WANG Zheng-ning, LIU Bo

2018, 37(2):  332-338. 

Asbtract ( 614 )   PDF (513KB) ( 267 )  

The niche theory is widely used to explain the interspecific coexistence andcompetition mechanisms in the communities, which is of significance for understanding the coupling between plant community assembly and environmental factors. By investigating the herbaceous communities in the understory of mature Chinese fir plantation (Cunninghamia lanceolata), Shannon, Levins niche width indexes, Levins niche overlapping indexes and ecological responding were used to analyze the niche characteristics of the herbaceous plants. The results showed that the niche width of the herbaceous plants in the mature Chinese fir plantation was not high. The niche width index ofB_(SW) (3.6254) and B_(L) (0.7069) were the largest for Woodwardia japonicadue to its wide distribution and strong adaptation to environment. W. japonica and Mussaenda pubescens with large niche width had higher niche overlapping with other dominant species. In general, relatively lower niche overlapping among species were apparent in the herb layer in the understory of Chinese fir plantation, indicating that the ability of species for sharing resources was weak. Our study suggested that most of the dominant species of herbaceous plants were in developing stage due to low niche overlapping, and that Chinese fir plantation community tended to be relatively stable.

Effects of tending on functional diversity of understory vegetation inPinus tabuliformis plantation on the Loess Plateau.

YUAN Zhi-jian, WANG Xiao-an, WANG Li-juan, HAN Bing-bing, LI Jing

2018, 37(2):  339-346. 

Asbtract ( 482 )   PDF (706KB) ( 217 )  

Understory vegetation is an important component of forest ecosystem. Restoring understory biodiversity is one of the primary objectives in forest management. The specialgeographic environment on the Loess Plateau has resulted in poor availability of effectiveunderstory tending measures. Furthermore, previous studies on changes of understory vegetation diversity in post-tending forests have mostly focused upon species diversity, but rarely uponfunctional diversity. The present study investigated the differences of the functional diversity in the understory between the tended and untendedPinus tabuliformis plantations on the Loess Plateau. The results showed that: (1) Soil temperature, moisture, salinity and indirect site factor significantly increasedunder the tended forest. (2) The tended forest was significantly higher than the untended forest in leaf area (LA), leaf dry matter content (LDMC) and leaf thickness (L_th) of the herb layer, but was significantly lower in specific leaf area (SLA). L_th  of the shrub layer was significantly higher in the tended forest than that in the untended forest. (3) Forsingle-trait functional diversity indices, the tended forest exhibited significantly higher functional richness (FR_ci) of LA, SLA andL_th of the herb layer, lower functional regularity (FRO) of SLA and LDMC of the herb layer and higher functional divergence (FD_var) of SLA andFR_ci of L_th of the shrub layer than did the untended forest. (4) For multitrait functional diversity indices, the tended forest displayed significantly higher functional richness (FR_ic) of the herb layer,significantly lower functional evenness (FE_ve) and functional divergence (FD_iv) of the herblayer, and significantly higherFE_ve of the shrub layer than the untended forest. These findings suggested that forest tending improved the understory environmental conditions. Tending exerted obviously greater effects upon the herb layer than upon the shrub layer. Properly raising theintensity of tending may further improve the functional diversity of understory vegetation.

Vegetation numerical classification and ordination of a 20hectare tropical forest plot in Xishuangbanna, Southwest Yunnan.

ZHANG Rong, DONG Ting-fa, DENG Xiao-bao, LIU Jun-yan

2018, 37(2):  347-352. 

Asbtract ( 527 )   PDF (609KB) ( 227 )  

To distinguish the vegetation types of tropical forest and understand the relationship between the community characteristics and topographical factors, we investigated the vegetation characteristics and topographical factors of 500 quadrats in a 20 hm² forest dynamics plot (FDP) in Xishuangbanna. Cluster analysis was used for community classification. The detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used toassign ordination of the forest communities. The results showed that: (1) The forest communities were classified into two types: tropical seasonal rain forest and tropical montane evergreen broad leaved forest; (2) The result from CCA ordination of 500 quadrats was consistent with that from cluster analysis, and CCA axis 1 and axis 2 showed the change of elevation and convexity gradient, which explained 83.9% of vegetation distribution pattern, indicating that the elevation and convexity factors played a crucial role in driving the distribution of vegetation types in the FDP; (3) DCA and CCA of dominant species showed that adaptation of plant species to thetopography was different and the distribution pattern of those species were mainly affected byelevation and convexity; (4) The results of cluster analysis, DCA and CCA unequivocallyindicated the existence of vertical distribution pattern of forest vegetation in the FDP. Therefore, the inherent relationship between vegetation distribution and topography could be uncovered by the combination of both methods, thus shedding new light for the management and conservation of tropical forests.

 

Plant-soil feedback effects of four common species in the Inner Mongolia Steppe, China.

QU Yao-bing, REN Hui-qin, GAO Shao-bo, ZHAO Nian-xi, GAO Yu-bao

2018, 37(2):  353-359. 

Asbtract ( 550 )   PDF (755KB) ( 258 )  

Plant-soil feedback plays an important role in explaining the change of community composition and in predicting the community dynamics, and thus becomes a hot point in the field of community ecology and restoration ecology. In the present study, we selected four common species,Leymus chinensis,Stipa grandis,Stipa krylovii and Agropyron cristatumfrom a community in the Inner Mongolia Steppe, and examined the plant-soil feedback with a two phase method. In the first phase, we planted those four species in monoculture and compared the soil differenceamong different monocultures. The soil was then named as S-the initial of the Latin name of a plant species, i.e., S-Lc, S-Sg, S-Sk, S-Ac, respectively. In the second phase, we examined the plant-soil feedback effects on the subsequent plants at both species and community levels. There were significant differences among species treatments in soil C∶N ratio, soil available phosphorus content and soil pH value (P<0.05). The plant-soil feedback effects were species specific.L. chinensisandA. cristatum showed the best performance for all five variables observed (tiller number, plant height, aboveground biomass, belowground biomass and totalbiomass) in the S-Sk, S. kryloviishowed the best performance for all five variables observed in S-Lc,S. grandis showed the largest tiller number and greatest plant height in S-Ac, and the largest amount of biomass in S-Lc. There were significant negative feedbacks for S. grandis andS. krylovii, neutral feedback forA. cristatum, and neutral to weak positive feedback forL. chinensis as indicated by the feedback effect value. The net pairwise feedback values among the fourspecies were negative, and the values between S. kryloviiandL. chinenses, and between S. krylovii andA. cristatum were significantly less than zero, indicating the probability of coexistence for these pair wised species. These results would help to predict the effects of plant community composition change on soil properties and the performance of subsequent plants and interspecific relationships among common species in the Inner Mongolia Steppe.

Soil fertility of olive orchards along an altitude gradient in Bailong River basin of Longnan, Gansu Province.

JIAO Run-an, LI Chao-zhou, ZHAO Yang, JIAO Jian

2018, 37(2):  360-365. 

Asbtract ( 458 )   PDF (463KB) ( 238 )  

Soil fertilities of olive orchards  from five different altitudes (960, 990, 1021, 1052 and 1083 m) in Bailong River basin was comprehensively assessed by using the subordinate function method and principal component analysis (PCA) to explore the impacts of altitude on soil fertility. The results showed that at the altitude of 960 m, the activities of soil urease andsucrase were the highest, and soil organic matter content and bulk density were the highest, while the pH value was significantly lower than that at other altitudes. The activities of soil phosphatase and catalase were the highest at 990 m. Soil water content was the highest at 1021 m. Soil available phosphorus and nitrogen contents were the highest at 1052 m. Among the five altitudes, soilbacteria abundance showed no significant variation, but being significantly higher than that at 1083 m. There were no significant difference in the abundance of soil actinomyces and fungiamong all the altitudes. The comprehensive indexes of soil fertility assessed by calculating the weight via correlation coefficients were ranked as 960 m > 990 m> 1052 m > 1021 m > 1083 m. The ranking of the comprehensive indexes using principal component analysis were 960 m > 990 m > 1021 m > 1052 m> 1083 m. The results of two analytical methods differed at 1021 m and 1052 m, but the soil fertility generally showed a decreasing trend with the increases of altitude.

Effects of altitude on seed size and number ofParis polyphylla var. yunnanensis.

GAO Cheng-jie, ZHANG Ting-ting, TANG Guo-yong, LIU Fang-yan, LI Kun

2018, 37(2):  366-373. 

Asbtract ( 428 )   PDF (707KB) ( 214 )  

The relationship between seed size and number is an important topic in the research of plant reproduction strategy. The seed number, size, and aborted number in each fruit ofParis polyphylla var.yunnanensiswere investigated in Jingdong (1984 m a.s.l.) and Zhenyuan (1025 m a.s.l.) of Puer, Yunnan Province, to better understand: (1) the effects of altitude on seed size and number and (2) the relationship between the aborted seed number and the seednumber/size. The results showed that there was no significant difference in total seed number per fruit between Jingdong and Zhenyuan (P>0.05). The filled seed number per fruit in Jingdong was significantly higher than that in Zhenyuan (P<0.05), and the aborted number wassignificantly lower than that in Zhenyuan (P<0.01). The seed size in Zhenyuan was slightly though not significantly higher than that in Jingdong (P>0.05). The seed abortion rates were positively correlated with the seed numbers in Zhenyuan (P<0.01), and the similar correlation with the seed size was observed in Jingdong (P<0.05). The negative correlation between seed size and seed number was found at different altitudes, suggesting the existence of seed sizenumber tradeoff inP. polyphylla var.yunnanensis. The regression coefficient between the seed size and number in Zhenyuan was significantly lower than that in Jingdong (P<0.05), implying the sensitivity of the tradeoff between seed size and number ofParis polyphylla var.yunnanensis to the changes of altitude.

Effects of soil moisture on stem respiration and non-structural carbohydrates ofDalbergia odorifera in the dry season.

CUI Zhi-yi, XU Da-ping, YANG Zeng-jiang, ZHANG Ning-nan, LIU Xiao-jin, HONG Zhou

2018, 37(2):  374-382. 

Asbtract ( 418 )   PDF (889KB) ( 143 )  

To investigate the effects of soil moisture on predawn shoot water potential (ψ_pd), stem respiration (R_s) and non-structural carbohydrates (NSCs) during the dry season, four soil moisture levels including heavy drought (HD), light drought (LD), dry-season irrigation (DI) and control (CK) were set up inDalbergia odorifera plantations. All those parameters weremeasured semimonthly. Soil moisture content and ψ_pd declined continuously and had significant differences among treatments after November.R_s increased exponentially with temperature and the coefficients of determination were all greater than 0.65.Q₁₀ differed significantly amongtreatments, following the order of DI>CK>LD>HD. Stem temperature (T) andR_s declinedcontinuously during the dry season and reached their minimum values in January. There was no significant difference of temperature among moisture treatments except in winter. Irrigationincreased theR_s rate, and drought decreased it. The soluble sugars tended to increase during the dry season at the cost of starch, which caused a small but non-significant increase in NSCs. The effect of moisture treatments on the content of total NSCs was limited; however, the droughttreatment increased the soluble sugars content and decreased the starch content. Low soil moisture induced by drought enhanced the transformation of starch to soluble sugars during winter, when heartwood formed.R_s explained 72% and 49% of the seasonal variation in starch and solublesugars, respectively. Theψ_pd explained 49%, 75% and 85% of the variance in theR_s, stem starch and soluble sugars, respectively. Soil moisture likely affectsR_s by modulating the amounts of sapwood starch and soluble sugars. These strong relationships provide evidence for the hypothesis that drought would promote heartwood formation inD. odorifera. In addition, given the significant relationship betweenR_s and NSCs, the variation in theR_s may also indicate changes in heartwood formation.

Effects of shading and provenance on triterpenoid accumulation in leaves ofCyclocarya paliurus.

DENG Bo, LIU Gui-hua, YU Yun-yun, XU Dan-dan, YE Qing-qing, FANG Sheng-zuo

2018, 37(2):  383-390. 

Asbtract ( 370 )   PDF (586KB) ( 151 )  

Cyclocarya paliurus, a multiple functional plant, has traditionally been used for drug formulations or ingredients of functional foods in China. Previous studies showed that the leaves of C. paliurus contain many physiologically active compounds (mainly triterpenoids) which were known to perform important physiological activity in human body. In the present study, a splitplot randomized design was used to examine the effects of shading (three levels) and provenance (three provenances) on triterpenoid content and triterpenoid accumulation over a growing season. Three shading levels were subjected to three light intensities, including 100% solar radiation (A1, without shading net), 30% of full solar radiation (A2, covered with one layer of shading net at 2 m height), and 12% of full solar radiation (A3, covered with two layers of shading net at 2 m height). Three provenances were Wufeng (B1) from Hubei Province, Yuanling (B2) from Hunan Province, and Muchuang (B3) from Sichuan Province. Our results showed that shading significantly affected the photosynthetic photon flux density, air temperature, and relative humidity, and thus significantly decreased the biomass accumulation. The highest biomass was detected in treatment A1B3. The interaction of shading and provenance significantly influenced the triterpenoid contents in leaves ofC. paliurus. The contents of cyclocaric acid B and arjunolic acid in provenances B1 and B2 were decreased in 30% light transmittance (A2) but increased in 12% light transmittance (A3). The highest contents of cyclocaric acid B and arjunolic acid were detected in 12% light transmittance. For provenance B3, however, the contents of cyclocaric acid B and arjunolic acid were positively correlated with increasing shading level. In addition, except for A2, the contents of cyclocarioside I in provenances B1 and B3 were decreased with thedeclined light intensity, with the variations ranging 0.20-0.27 mg·g^-1 and 1.33-2.52 mg·g^-1, respectively. Both the main and interactive effects of shading and provenance had significant influence on triterpenoid yield per plant. The highest yield of total triterpenoid and cyclocarioside I was detected in treatment A1B3, with the mean values of 2523.4 and 208.5 mg per plantrespectively, while the highest yields of cyclocaric acid B and arjunolic acid were found intreatment A2B3. The lowest yields of total and three individual triterpenoids were detected in A3 treatment. Overall, our results suggest a complex relationship between light environment,genotype and triterpenoid production, and highlight that selecting suitable provenance ofC. paliurus and optimizing cultivation system would be crucial for a high triterpenoid production.

Effects of pruning on allometric relationship between height and basal diameter ofMoringa oleifera.

ZHAO Guang, HAN Xue-qin, WANG Xue-mei, LIAO Cheng-fei, YAN Bang-guo, LIU Gang-cai, LI Gui-hua, JIN Jie

2018, 37(2):  391-398. 

Asbtract ( 403 )   PDF (687KB) ( 189 )  

Allometric relationships between height and basal diameter reflect the tradeoff ofresource allocation between vertical and horizontal growth in trees under different environmental conditions. Understanding the effects of pruning on the allometric relationship between height and basal diameter can contribute to exploring the tree resource allocation mechanism underenvironmental stress. This study investigated the effects of pruning methods on growth and allometric relationship between height and basal diameter ofMoringa oleifera in Yuanmou dry and hot valley. The results showed that there were significant differences in height and basal diameter among pruning 50%, pruning 100%, pruning 100%+topping and control treatments (P<0.05). At the late stages of measurement (12 and 16 weeks), there was no significant difference in height between pruning 50% and control treatments (P<0.05) and the growth rates in basaldiameter of pruning 50% and pruning 100% were higher than that in control treatment, implying thatM. oleifera  might evolve compensatory growth after pruning. The General Linear Models (GLMs) and the Standardized Major Axis Estimation (SMA) had the same determinationcoefficients, but the allometry coefficients of GLMs were lower than that of SMA (84.9%-91.9%). Allometry coefficient increased with the increases of pruning intensity, whereas topping decreased the coefficient. Such a phenomenon indicated thatM. oleifera would allocate moreresources to vertical growth under pruning, while topping had the opposite impacts. Pruning 50% was recommended for the management ofM. oleifera in practice.

 

Effects of plant growthpromoting rhizobacteria on alleviating consecutive monoculture problem ofPseudostellaria heterophylla under field conditions.

WEI Xiao-ya, LIN Yu, CHEN Ting, TAO Zi-xi, ZHAO Han-yu, LIN Sheng, LIN Wen-xiong

2018, 37(2):  399-408. 

Asbtract ( 422 )   PDF (1925KB) ( 222 )  

Pseudostellaria heterophylla is a valuable herbal medicine, which experiences serious yield decline under consecutive monoculture. This study aimed to evaluate the effects of different microbial fertilizers using plant growthpromoting rhizobacteria (Bacillus subtilis andBurkholderia as main component) on the continuous cropping obstacle ofP. heterophylla, taking mixture of soybean pulp and pig manure as a control.P. heterophylla rhizosphere soils were collected from six treatments: basal control (CK), firstrotation planting (FP), secondrotation planting (SP),Bacillus subtilis fertilizer (No. 1),Burkholderia fertilizer (No. 2), Bacillus subtilis and Burkholderia mixed fertilizer (No. 3), to investigate physicochemical properties and fungal community structure inP. heterophylla rhizosphere soils. The results showed that three kinds of microbial fertilizers (No. 1, No. 2 and No. 3) significantly increased the yield of P. heterophylla by 107%, 112% and 96% compared to SP treatment, respectively. In addition, these bio-fertilizers significantly improved soil pH and available nitrogen (AN) content but reduced the contents of available potassium (AK) and phosphorus (AP). These results indicated that large amounts of functional bacteria existed in the bio-fertilizers, which could effectively promote soil nutrientavailability. The DGGE results demonstrated that the fungal community structure under the treatments of bio-fertilizer No. 2 and No. 3 was similar to that in firstrotation planting (FP), which was further confirmed by qPCR results. Our results indicated that the application of bio-fertilizers could improve the yield by influencing soil microbial community structure and function in thecontinuous cropping systems of P. heterophylla. These results exemplify the potential of bio-fertilizers in reducing the effects of replanting disease and in improving soil quality, providing clues onoptimizing cultivation techniques ofP. heterophylla under continuous cropping.

Effects of high temperature stress on senescence and endogenous hormone of cucumber during flowering period.

XUE Si-jia, YANG Zai-qiang, ZHU Li-yun, LI Jun

2018, 37(2):  409-416. 

Asbtract ( 443 )   PDF (638KB) ( 215 )  

To explore the effects of high temperature stress on the senescence characteristics and the dynamics of endogenous hormones in leaves of cucumber at flowering stage, we established an artificial environment within which temperature was controlled and selected cultivar ‘Nan Za Ⅱ’ as experiment material. Four levels of daily/night temperature were treated as 42  ℃/32  ℃,39  ℃/29  ℃, 36  ℃/26  ℃, and 24  ℃/18  ℃ (control); the durations of treatment time were 1, 3, 5, and 7 d, respectively. The contents of chlorophyll a, chlorophyll b, carotenoids andchlorophyll a+b, the activities of SOD, POD and CAT, and the content MDA, ABA, IAA, GA-3 and ZT were measured. Treatment of 42  ℃/32  ℃ with a duration of 7 d significantly reduced the contents of leaf chlorophyll a, chlorophyll b, and carotenoids, the activities of POD and SOD, and the contents of IAA, GA3, and ZT by 16.61%, 23.17%, 73.33%, 17.89%, 56.90%,94.16%, 54.32%, 90.68%, respectively, but enhanced leaf MDA content (+62.66%), CAT activity(+28.06%), and ABA content (+294.35%) in apical bud. Our results showed that shortterm high temperature stress increased the chlorophyll content of cucumber leaves and that the chlorophyll b content decreased gradually with the increase of temperature and extension of stress time. Shortterm high temperature stress increased the activities of antioxidant enzymes in cucumber leaves, but decreased gradually with the increased intensity of high temperature stress. An increasing trend of ABA content in cucumber leaves was detected under high temperature stress, while the changes of IAA, GA3 and ZT contents showed an opposite trend. Results from this study provide scientific basis for temperature management of cucumber cultivation.

Effects of mowing plus waterlogging on germination and seedling growth of Spartina alterniflora.

XIE Bao-hua, WANG An-dong, ZHAO Ya-jie, ZHU Shu-yu, SONG Jian-bin, HAN Guang-xuan, GUAN bo, ZHANG Li-wen

2018, 37(2):  417-423. 

Asbtract ( 501 )   PDF (1138KB) ( 203 )  

Spartina alterniflora is one of the most noxious invasive plant species in China. Exploring  environment friendly, economic and effective technique of controlling S. alterniflora is of great significance for the protection of the coastal environment. In the present study, the effects of mowing and waterlogging on germination and seedling growth of S. alterniflora were studied by a pot experiment in an artificial climate chamber (20-25 ℃). The experiment lasted for four months andS. alterniflorawas mown twice. The first mowing was carried out at the end of the growing season ofS. alterniflora and the second mowing occurred three months later. After the first mowing, the soils were continuously waterlogged. Four waterlogging depths were set up: 0, 5, 10, and 20 cm. The seedlings sprouted rapidly on the rhizome ofS. alterniflora after the first mowing. The germination of seeds was about three months later than that of clonal seedlings.Waterlogging inhibited the germination and growth of clonal seedlings. The number of clonalseedlings, plant height and aboveground biomass decreased with the increases of waterlogging depth. After the second mowing, no clonal seedlings reappeared; however, a small amount of seeds germinated in waterlogging treatments. The number of seedlings in the 20 cm waterlogging treatment was the least. According to our results, mowing plus waterlogging can inhibit thegermination and seedling growth of S. alterniflora. Furthermore, mowing and waterlogging is not harmful to the environment. The recommended control technique ofS. alterniflora is: (1) building a dam before the spring germination and waterlogging the soil at 20 cm depth, (2) mowing the aboveground part ofS. alterniflorain the later stages of vegetative growth and continuedwaterlogging, and (3) repeating mowing and waterlogging in the second year. In order to prevent secondary invasion, it is necessary to simultaneously implement the same technique in theadjacentS. alterniflora growth area.

Hyperspectral estimation of aboveground dry biomass of winter wheat based on thecombination of vegetation indices.

JIA Xue-qin, FENG Mei-chen, YANG Wu-de, WANG Chao, XIAO Lu-jie, SUN Hui, WU Gai-hong, ZHANG Song

2018, 37(2):  424-429. 

Asbtract ( 491 )   PDF (509KB) ( 199 )  

This study aimed to explore the effects of the combination of various vegetation indices and partial least squares regression (PLSR) on improving the evaluation accuracy of aboveground dry biomass of winter wheat. The experiment was based on nitrogen operation test and wasconducted to analyze the correlation between 18 vegetation indices and the aboveground drybiomass of winter wheat. The better vegetation indices were selected to establish the PLSR model as a combined vegetation index, and the model performance was then evaluated. The results showed that, except for the chlorophyll normalized vegetation index (NPCI), a good correlation was observed between the vegetation indices and aboveground dry biomass of winter wheat.Especially, the correlation coefficients of the four indices, i.e., MERIS terrestrial chlorophyll index (MTCI), green normalized difference vegetation index (GNDVI), modified red edge ratio vegetation index (MSR705), and pigment specific simple ratio carotenoids (PSSRc), were greater than 0.800. Among the PLSR models established with vegetation index combination, the model calibration set (R²=0.719, RMSE=0.316) and validation set (R²=0.696,RMSE=0.346) based on the combination of PSSRc, MSR705, and MTCI performed best. Therefore, we concluded that the combination of multiple vegetation indices could improve the estimation accuracy of aboveground dry biomass of winter wheat. This study provides an effective approach for hyperspectral remote sensing estimation of the aboveground biomass of winter wheat.

Effects of Chinese milk vetch as a green manure and nitrogen fertilization on rice growth and nitrogen absorption and utilization of rice.

ZHANG Ying-rui, YANG Bin-juan, HUANG Guo-qin

2018, 37(2):  430-437. 

Asbtract ( 411 )   PDF (493KB) ( 195 )  

The purpose of this experiment is  to screen out the optimal match ratio of the recycling amount of Chinese milk vetch (Astragalus sinicus L.) and the application level of nitrogen fertilizer and thus to provide theoretical basis for improving rice production. This experiment adopted a split plot design with no application of Chinese milk vetch or nitrogen as control one (CK1), the conventional nitrogen application level (180 kg·hm^-2) as control two (CK2). The application of Chinese milk vetch included two levels: 27000 and 45000 kg·hm^-2 (designated M1 and M2 respectively), and the application of nitrogen fertilizer included four levels: 0, 60, 120 and 180 kg·hm^-2 (designated N0, N1, N2, N3 respectively). The effects of coupling different amounts of Chinese milk vetch and nitrogen on rice yield, dry matter accumulation and nitrogen useefficiency of rice were examined. The results showed that the applications of 27000 kg·hm^-2 of Chinese milk vetch + N ≥120 kg·hm^-2 and 45000 kg·hm^-2 of Chinese milk vetch + N ≥60 kg·hm^-2 could ensure the rice yield and growth. M1N2 had the highest yield, being 11.56% higher than CK2. In the ripening stage of rice, dry matter accumulation of M2N1 was thehighest, being 21.41% higher than CK2; nitrogen absorption amount of M2N3 was maximum, being 5.32% higher than CK2. The apparent and real utilization of nitrogen fertilizer decreased with the increases of nitrogen application level. The treatments of M1N2 and M2N1 can ensure the rice yield and  improve the utilization rate of nitrogen fertilizer, which would be beneficial to the efficientutilization of resources.

Functional groups of fish community in the Huayang lake group and their response toenclosure culture.

XIA Zhi-jun, JIANG Zhong-guan, XIE Han, GUO Wan-yun, WANG Chao

2018, 37(2):  438-445. 

Asbtract ( 510 )   PDF (819KB) ( 226 )  

The impacts of enclosure aquaculture on fish fauna were examined by investigating the fish communities in enclosure (EA) and non-enclosure (NEA) aquaculture areas in the Huayang lake group across different seasons in 2016. Functional traits related to diet, morphology, ecological habits, and life history were selected to classify and define functional groups by cluster analysis. The impacts of enclosure aquaculture on fish communities were examined by comparing the changes of species composition and biodiversity of functional groups. The results showed that a species pool of 65 species belonging to 41 genera, 12 families and 6 orders could be classified into 17 independent and distinct functional groups. The density of functional groups G1, G3, G4,  G5, G11, G12, G13 and G15 were significantly lower (P<0.05), while the groups G9 and G10 were significantly higher (P<0.05) in EA than in NEA. Moreover, the functional group richness and Margalef’s index in EA were significantly lower (P<0.05), whereas the Pielou’s evenness index was significantly higher (P<0.05) in EA than in NEA. Our results indicated that enclosure aquaculture could significantly alter the community composition and biodiversity of fish functional groups.

Geographic variation of morphological characteristics and female fecundity in different populations ofRana chensinensis.

YU Qing, CHEN Hui, ZHAO Wen-ge, LIU Peng

2018, 37(2):  446-452. 

Asbtract ( 440 )   PDF (702KB) ( 180 )  

A total of 130 specimens from twoRana chensinensispopulations were collected in this study, with the Zhengzhou population (Henan Province) being the southern part of the range and the Zhalantun population (Inner Mongolia) being the northern part of the range. Female fecundity and 26 morphological characters in males and females were measured to examine geographical variation of different populations. The results showed that females were significantly larger than males. The body size of Zhalantun population was significantly larger than that of Zhengzhoupopulation, which is in accordance with Bergman’s rule. However, the length of the limbs was also larger in the cold climate that does not conform to Allen’s rule. Sexual size dimorphism inR. chensinensis did not obey Rensch’s rule. Females should be more sensitive to environmental changes because they could grow faster than males in snout-vent length and weight which ensures their greater reproductive success. The different variation trends in body sizes between females and males across different environment imply the substantial differences in their adaptationstrategies, which should be the main reason for geographic variation in morphologicalcharacteristics and female fecundity across different populations.

Effects of imidacloprid on interspecific competition betweenFrankliniella occidentalis andF. intonsa and their progeny development.

HU Chang-xiong, LI Yi-ru, LI Zheng-yue, CHEN Guo-hua, ZHANG Hong-rui, GUI Fu-rong, ZHANG Xiao-ming

2018, 37(2):  453-461. 

Asbtract ( 476 )   PDF (695KB) ( 188 )  

In this study, we aimed to clarify the effects of imidacloprid on interspecific competition between thripsFrankliniella occidentalis andF. intonsa by recording the developmental and fecundity parameters of both species in a competition experiment under laboratory conditions. The LC₅₀ concentrations of imidacloprid in both species were measured by dipping feeding method. Both species were reared on beans in the same cage with a starting ratio of 1∶1 under pesticide stress at the predetermined LC₅₀ concentration on 2nd instar larvae ofF. intonsa. The results showed that there was a consistently higher proportion of females in both species from 25 d to 150 d, with the female excess being higher inF. occidentalisthan in that inF. intonsa underimidacloprid stress (P<0.05). The developmental duration of the immature stages in both species were significantly shorter than in the control, and F. occidentalis developed consistently faster thanF. intonsa(P<0.05). The population survival rate and the longevity of male and femaleadults ofF. occidentalis were slightly higher than that ofF. intonsa, but the difference was not significant (P>0.05). The net reproductive rate (R₀), the intrinsic rate of increase (r_m) and the growth rate (λ) ofF. occidentaliswere significantly higher than that ofF. intonsa. Thelongevity of both male and female adults, the mean length of generation (T) and populationdoubling time (DT) of both species in the pesticide treatments were significantly shorter (P<0.05) than that in control. Average fecundity, R₀,r_m and λ inF. occidentalis were significantly higher than that in control (P<0.05), while average fecundity, R₀,T and DTof F. intonsa were significantly lower. Overall,F. occidentalis was more adaptable thanF. intonsato imidacloprid stress, with females being more adaptable than males for both species. Imidacloprid stress is one of the key reasons for the accelerated replacement ofF. intonsaby F. occidentalis populations.

Analysis of structure and energy flow in Jiaozhou Bay ecosystem based on Ecopath model.

MA Meng-lei, CHEN Zuo-zhi, XU You-wei, ZHANG Kui, YUAN Wei, XU Shan-nan

2018, 37(2):  462-470. 

Asbtract ( 666 )   PDF (1059KB) ( 331 )  

Based on the survey data of fishery resources and ecological environment in the Jiaozhou Bay during 2015-2016, we developed a mass-balance model using Ecopath with Ecosim software for the Jiaozhou Bay. Using the Ecopath model, we evaluated the trophic structure,energy flow and ecosystem characters of the Jiaozhou Bay. The Jiaozhou Bay model consisted of 21 functional groups, and the fractional trophic levels ranged from 1 to 4.383. The mean trophic level of fishery catches in the Jiaozhou Bay ecosystem was 2.023, dominated by Manila Clam (Ruditapes philippinarum). The energy flow of the Jiaozhou Bay ecosystem was mainly dominated by grazing food chain, which accounted for 59% of the energy source. Using network analysis, the system network was mapped into a linear food chain and six discrete trophic levels were found with a mean transfer efficiency of 16.35%, 16.22% from primary producer and 15.76% from detritus within the ecosystem. In addition, the ratio of total primary production/total respiration (TPP/TR) was 2.518, suggesting that the Jiaozhou Bay ecosystem was in an immature state.

 

Evaluation and impact factors of  environmental pollution of China based on spatial metric model.

GUO Si-dai, ZHANG Hua, GUO Jie, LU Cheng-peng

2018, 37(2):  471-481. 

Asbtract ( 542 )   PDF (1192KB) ( 252 )  

We calculated the environmental pollution index based on entropy method, analyzed its spatial features of clustering and agglomerating according to Moran scatter plot and LISAgathering figures, and investigated the impact factors of environmental pollution by using thespatial panel data model. The results indicated that the environment pollution level and associated development trend of China presented a certain degree of fluctuations; however, the industrial pollution emissions were relatively stable, and household living pollution became the main source for regional pollution. In addition, the environmental pollution showed strong regional differences, featured by significant spatial clustering and agglomeration. The results also manifested that the influences of different factors on environmental pollution varied in their direction and strength. Specifically, scientific technology, openness, and environmental awareness exerted reverseinfluences on the environmental pollution. This is because the openness and scientific technology can improve environmental quality, and the environmental awareness can lead to low environmental pollution, but with time-lag effects. Based on those findings, we put forward some suggestions in related policy, including strengthening cooperation in regional environmental governance,moderating agglomeration of population space, enlarging the scale of environmental governance investment, deepening the opening up level, and encouraging innovation in industrial science and technology.

Chemical characteristics and health risk assessment of groundwater from large coal-mining area in Shaanxi and Inner Mongolia of China.

CAI Yue, LI Xiao-ping, ZHAO Ya-nan, SUN Xue-meng, LIU Dong-ying, WU Ting, AI Yu-wei, YANG Tao

2018, 37(2):  482-491. 

Asbtract ( 362 )   PDF (734KB) ( 183 )  

Twenty-two water parameters of groundwater collected from six large coal-mining areas in Shaanxi and Inner Mongolia of China, including physical and chemical properties, major ions and potential toxic elements (PTE) (As, Hg, Cr, Cu, Cd, Pb, Zn and Ni), were investigated with automatic water analyzer, ion chromatography (IC), atomic fluorescence analyzer (AFS), and inductively coupled plasma mass spectrometry (ICP-MS). The pollution status and health risk were evaluated by fuzzy comprehensive method and USEPA chemical carcinogens model,respectively. Results showed that the ground water (below 300 m) ranked the first grade in water quality according to the standard of GB/T 14848-93. The contents of main cations and anionsdecreased as Mg²⁺>Na⁺>Ca²⁺>K⁺ and SO₄²>Cl^->NO₃^->F^-. SO₄·Cl-Na and bicarbonate were the main water types. Although the cancer and non-cancer risk of most PTEs exposure to adults and children were within acceptable limits, the PTEs Cr and As were more likely to cause health risks to children and adults than other elements. Moreover, Cr had a greater cancer risk forchildren compared to As for adults. It is important to note that the health risk from PTEs tochildren was greater than that to adults. The total health risks of PTEs in groundwater fromHalagou, Wangqugou and Guadiwan coal mine areas exceeded the critical load of 5.0×10^-5 a^-1 recommended by International Commission on Radiological Protection (ICRP). Our resultshighlight that more attention should be paid on the health risk of PTEs in groundwater from those areas.

Remediation efficiency ofEchinacea purpurea for heavy PAHs contaminated soils.

ZHANG Xiao-qing, XU Li, QI Yue, SUN Li-bo, ZHANG Que

2018, 37(2):  492-497. 

Asbtract ( 482 )   PDF (481KB) ( 194 )  

The phytoremediation potential ofEchinacea purpurea on PAHs heavily contaminated soils was investigated with pot experiment. The polluted soils were collected from an oil field. Two types of soils with different concentrations of PAHs (122.40 and 183.60 mg·kg^-1) were prepared by adding a given proportion of polluted soil, non-polluted soil, sandy soil, and PAHs multicompound standards. The height and biomass ofE. purpurea, and the removal rate of four kinds of PAHs, pyrene(Pyr), chrysene (CHR), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), were measured. The results showed that: (1) The height and biomass were significantly inhibited by PAHs, but E. purpurea still could survive with the total PAHsconcentration at 183.60 mg·kg^-1. (2) The removal rates of Pyr, CHR, BbF and BkF were 66.2%, 70.3%, 40.6% and 65.4%, respectively. The total PAHs decreased from 183.60 mg·kg^-1 to 104.52 mg·kg^-1. The total removal rate of four kinds of PAHs was 56.93%, which was much higher than that in the control. This result demonstrated thatE. purpurea has a good potential for phytoremediation of heavily PAHs contaminated soils. The significant correlation between theremoval rate of PAHs and belowground biomass indicated that the belowground biomass of plants had a greater influence on the removal rate of PAHs. This study expanded the application range of phytoremediation on PAHs contaminated soils.

Allelopathy of aqueous extract of cattail onMicrocystis aeruginosa.

DONG Yin-na, FENG Bin, WANG Bing-xuan, GUO Ming, FAN Xiao-yue

2018, 37(2):  498-505. 

Asbtract ( 413 )   PDF (796KB) ( 246 )  

The components with high allelopathic activity were separated fromTypha orientalis aqueous extract by liquidliquid partition and thinlayer chromatography. The components with high allelopathic activity were analyzed by gas chromatographmass spectrometry (GC/MS) toexamine the allelopathic effects of aqueous extract from different tissues ofT. orientalis onMicrocystis aeruginosa. The results showed that the inhibitory effects of different T. orientalis tissues were different, with the inhibitory effect of leaf extract > root extract > pollen extract. The inhibition rate of leaf extract onM. aeruginosa was up to 72.35%. The allelopathic effects of T. orientalis leaf aqueous extract onM. aeruginosa exhibited a phenomenon of inhibition at highconcentration (≥10 g·L^-1) while showed a trend of stimulation at low (≤5 g·L^-1). The allelopathic effects decreased the content of chlorophyll a, increased permeability of cellmembrane while initially increased then decreased SOD activity and MDA content. Results of GC-MS showed that the main allelochemicals from T. orientalis were phenolic acid, fatty acid, ester, ketone, amide, and so on. The results provide a theoretical guidance for the management ofaquatic ecosystems with algal blooms.

An assessment of the synchronization between urbanization intensity and environmental quality in Beijing-Tianjin-Hebei region.

YAN Shen, SUN Ran-hao, CAO Ming-ming

2018, 37(2):  506-513. 

Asbtract ( 425 )   PDF (1272KB) ( 373 )  

The correlation between urbanization and environmental quality has been well addressed in literatures, but few studies have been conducted in the regions of urban agglomeration. In this study, we constructed an evaluation index system of urbanization and environmental quality. These evaluation indices were used in 13 prefecturelevel cities (including two municipalities) and 20 county-level cities in Beijing-Tianjin-Hebei region. By using the coordinated development degree model, we analyzed the coordinated development degree between urbanization and theenvironmental quality in this region. The results showed that the comprehensive urbanization level in Beijing-Tianjin-Hebei region displayed the model of “polarization development”. In contrast, most of the county-level cities belonged to the low level. The environmental quality exhibitedsignificant differences in prefecture level cities. Tianjin City had the highest degree of coordinated development, followed by Tangshan. However, the countylevel cities were in a moderate level. The coordination degree between urbanization and the environmental quality ranged from 0.37 to 0.83 in prefecturelevel cities, with higher values in Beijing-Tianjin-Tangshan region. Moreover, the coordination degree ranged from 0.22 to 0.65 in countylevel cities. The balanced pattern was in the northeastern Hebei, while the imbalanced pattern was in the southeastern Hebei. These results highlight the significant difference of coordination degree among cities in this region. Results from this study are useful for scientific evaluation and decision-making management in the coordinated development of Beijing-Tianjin-Hebei region.

Effects of land use change and planning regulation on ecosystem service values of islands: A case study of Putuo District, Zhoushan Archipelago.

SHAO Xiao-yun, ZHANG Ze-fei, LIU Zhong, JING Chang-wei, QI Jia-guo, JIANG Jin-gang, CAI Xiu-min, LIU Qian-kun

2018, 37(2):  514-522. 

Asbtract ( 574 )   PDF (1786KB) ( 320 )  

Using related methods of evaluating ecosystem service value (ESV), the ESV ofisland ecosystems in Putuo District, Zhoushan Archipelago was evaluated. The changes of ESV caused by land use change and the potential impacts of planned land use structure on ESV were analyzed. The results showed that the land use change was obvious in Putuo District from 2006 to 2012, with a substantial increase of construction land and a significant decrease of cropland and wasteland. The ESV increased by 32.0 million yuan from 2006 to 2012 due to the conversion of largearea cropland into waters, the ESV of which being higher. According to the land useplanning for the period of 2006 to 2020, the ESV in 2020 would decrease by 99.1 million yuan because land use types such as forest, water and tidal marsh with high ESV would be changed into those with relatively low ESV, such as construction land. Moreover, the construction land would be in excessive growth, while the cropland area could not meet the planning requirement. Therefore, the land use planning in 2006-2020 would be unable to meet the development ofPutuo District. Further adjustment should take the ESV into account to balance land userequirement and ecological protection of regional development.

Spatialtemporal changes and driving forces of rural settlements: A case study of Beilun District, Ningbo.

FENG Bai-xiang, LI Jia-lin, HE Gai-li, HUANG Ri-peng

2018, 37(2):  523-533. 

Asbtract ( 399 )   PDF (2760KB) ( 63 )  

Beilun, a district of Ningbo City, is located in the southeastern coastal area of China. Based on six periods TM/OLI remote sensing images of 1990, 1995, 2000, 2005, 2010 and 2015, we applied landuse dynamic index, conversion matrix, kernel density estimation, average nearest neighbor index and landscape pattern index to analyze the spatialtemporal dynamics and driving forces of rural settlements in the last 25 years in Beilun District. The results showed that the landuse dynamic index was generally positive in rural settlements, and the residential land showed a slow expansion trend. The average patch area of rural residential area in Beilun increased in the last 25 years, with an average annual growth rate of 2.51%. In the first twoperiods studied here, the average patch size was mainly affected by their number. In the later two periods, the total number of patch and the total patch area were the drivers. At the last period, the total area of the patches was the dominant driving factor. The differences of patch size among rural settlements were more and more significant. Agricultural land and forest land were the dominant types of land conversion in the settlements, especially for agricultural land. The urban construction had no obvious impacts on the settlements. The spatial patterns of rural settlements were in agglomeration in the west, dualcore interaction in center and scattered distribution in the east. In 2015, there was an obvious highdensity area near the northern islands (Daxie). Theoverall distribution of the settlements was changed from dispersed pattern into clusters, with the degree of agglomeration continuing to increase. The distribution of rural settlements in Beilun was affected by population density, road, landscape and policy. Population growth significantlyaffected the spatial patterns of rural settlements in 1995-2000 and 2000-2005. The directions of state roads and county roads were closely linked with the spatial distribution of settlements.Policies can promote the changes of distribution of settlements and lay the foundation for the future distribution. The settlements were mostly distributed in the low-lying area  (DEM <100 m).

Landscape pattern optimization based on granularity inverse method and GIS spatialanalysis.

LU Yu, SHE Ji-yun, LUO Gai-gai, CHEN Cai-hong, SHE Yu-chen, Li Chang-qing

2018, 37(2):  534-545. 

Asbtract ( 506 )   PDF (3180KB) ( 200 )  

Landscape pattern optimization is an effective way to build ecological networks, which can substantially improve the regional ecological security. This study, with Meilan district in Haikou City as the research area, objectively selected the ecological sources by the way of granularity inverse method and principal components analysis from the point of increasing the overall connectivity. The ecological network was built by combining the minimal cumulative resistance model. Through the spatial network analysis and hydrological analysis, this paper mainly discussed how to determine the scale, shape, and form of the ecological nodes. It’s an appropriate reference for the selection of ecological sources in Meilan district when the ecologicallandscape component granularity is 550 m. There were 38 ecological sources in Meilan district. The landscape types of 23 plaques needed to be converted. The scale and layout of ecological sources were different due to the anthropogenic influences. The difference between dominant and recessiveecological resistance indicated that there were five ecological frangible parts in Meilan district. The causing factors for such differences should be given full consideration when adaptive management strategies being taken during the construction of ecological networks. The mostcrucial one was to reserve ecological lands. The ecological network of Meilan district was made of 90 ecological corridors and 89 ecological nodes. Together with ecological sources, they improved the connectivity of ecosystem. Ecological nodes formed 79 ecological regions with a total area of 729.15 hm², within which 10 regions should be turned into aquatic systems and 69 regions into forests. We put forward a specific scheme for the construction of ecological nodes, which mayimprove the practical significance of landscape pattern optimization.

Hyperspectral characteristics of different species of Sphagnum L. in Hani peatland, Northeast China.

WANG Lin-feng, FENG Lu, LI Wei, WU Yu-huan

2018, 37(2):  546-553. 

Asbtract ( 502 )   PDF (3444KB) ( 157 )  

Few studies have examined the hyperspectral characteristics of Sphagnum species which are dominated in northern peatlands. Hyperspectral remote sensing technology was used in this study to explore the spectral characteristics of the same Sphagnumspecies in different water level conditions (hummock and hollow), and those of different Sphagnumspecies in the same water level conditions. The results showed that the spectral reflectance  varied across different Sphagnum species, with large difference in  green peak and  red edge. Due to the difference ofwater level conditions, the spectral reflectance in visible and infrared wavebands ofSphagnum fuscum, S. palustre, andS. magellanicum was different between highhummock and lowhummock populations, with the reflectance of highhummock species being higher than that of lowhummock ones. The detailed spectral information of severalSphagnum species in HaniSphagnumwetland in Northeast China obtained here would be helpful for interpreting thehigh resolution aerial photographs and satellite images of Sphagnumwetlands.

Sources and controls of nitric oxide from forest soils: A review.

QIU Qing-yan, HU Ya-lin

2018, 37(2):  554-568. 

Asbtract ( 586 )   PDF (870KB) ( 234 )  

In recent years, nitric oxide (NO) has been receiving more attention due to its important roles in biogeochemical cycling, atmospheric chemistry and global warming. Forest soils are among the major sources for atmospheric NO nitrification, denitrification, nitrifier denitrification and chemodenitrification are the four dominant processes for the production of NO from forest soils. However, the relative contributions of these sources to NO production, as well as the relationship between its production and the biotic (e.g. functional genes) and abiotic factors are still not well understood. Here, we reviewed recent literatures to fully understand each of the main processes producing NO in forest soils and the methods for measuring the contribution of each source to the NO production as well as the biotic (e.g. functional genes) and abiotic factors influencing its emission to the atmosphere. Moreover, the weaknesses of the present studies are poin-ted out, and the future research directions are provided. Overall, nitrification and denitrification are the major processes for NO production, but chemodenitrification in acidic forest soil cannot be ignored. The application of dual isotopic approaches (¹⁵N and ¹⁸O) may provide a key to better quantify the contributions of these processes to the emission of NO in forest soils. The production of NO involves complex biotic and abiotic processes. Up to date, few studies have focused on the relationship between the NO derived from different sources and the functional genes involved in nitrogen cycling. More attention has been paid to the effects of individual environmental factor on the production of NO via nitrification and denitrification, whereas studies about the effects ofenvironmental factors on the NO production via nitrifier denitrification and chemodenitrification are rare. Moreover, little information is avaibale about the comprehensive effects of environmental factors on NO production.

Micro-opography modification and its effects on the conservation of soil and water inartificially piled landform area: A review.

YANG Ya-shuang, WANG Jin-man, WAN De-peng

2018, 37(2):  569-579. 

Asbtract ( 474 )   PDF (597KB) ( 188 )  

Artificially piled landform is accumulated of the spoil resulted from the urban construction and mining activities. Tens of billions of cubic meters of spoils are made globally every year, which occupy a large amount of lands and lead to severe soil and rock erosion. Microtopography modification can effectively regulate surface runoff, control soil erosion, and improve surfacemicro-abitat. Here, we reviewed the erosion characteristics of artificially piled landform,summarized recent progress in the research of the microtopography modification methods, i.e., terrace, level bench, level trench, fishscale pit and waterproof ridge. The applicable field,advantages and disadvantages of different micro-opography modification methods were figured out, and the effects of different micro-opography strategies on sediment reduction, water and nutrient storage, and vegetation restoration were discussed. Furthermore, this review uncovered the problems in the methods of micro-opography modification and combined application of land preparation measures, and put forward the future research direction of runoff erosion mechanism and hydrological principles. This review provides a reference for the soil and water conservation of artificially piled landforms.

Research progress about phenotypic plasticity of exotic invasive speciesBidens pilosa and a congeneic native speciesB. biternate.

ZHENG Xin-ying, XUE Li

2018, 37(2):  580-587. 

Asbtract ( 531 )   PDF (554KB) ( 268 )  

Bidens pilosa L., an exotic invasive species,is one of worst weeds in many croplands in southern China. However, there are few systematic summaries of its invasion capability inChina. Here, we reviewed the research progress about phenotypic plasticity of exotic invasiveB. pilosa and a congeneic native speciesBidens biternate (Lour.) under different environmentalconditions. The differences of seed germination between those two species under different light conditions, temperatures and soil depths were discussed. Their biomass allocation patterns andreproductive characteristics were compared under different light, water, temperature and soil nutrient conditions. The mechanism of successful invasion ofB. pilosa includes rapid propagation,wide ecological adaptation, and allelopathy of root exudates. Finally, prospects about B. pilosa for further studies were proposed and methods for management and control strategies  of B. pilosa invasion were summarized.

A review on biogenic volatile organic compounds  emitted from common flower plants.

HU Chun-fang, YUAN Xiang-yang, TIAN Yuan, FENG Zhao-zhong

2018, 37(2):  588-595. 

Asbtract ( 593 )   PDF (537KB) ( 437 )  

The biogenic volatile organic compounds (BVOCs) released by flower plants have effects on atmosphere quality, global climate change and human health. Here, we reviewed the progress on the basic concept and function of BVOCs, the types and emission rates of VOCs  emitted from common flower plants, components and effects of VOCs, and the internal factors such as developmental stage and organs and the external factors such as temperature, photoperiod and water condition that driving variation of VOCs emission. In addition, due to few studies on the negative effects and longterm measurement of VOCs emitted from flower plants, such research is needed in the future. More attention should be paid on the components and rate of VOCs emitted from flower plants under multiple environmental factors, and longterm and dynamic processes of VOCs emission. The negative impacts of VOCs emitted from flower plants on the environment quality and human health are also warranted.

Multi scale eco-environmental quality evaluation method from a spatial perspective.

CHAI Yan-ni, WEI Guan-jun, HOU Wei, FENG Zhi-xian, ZHAI Liang

2018, 37(2):  596-604. 

Asbtract ( 456 )   PDF (6561KB) ( 205 )  

This study shows the efforts for establishing an evaluation index system based on the PSR (Pressure-State-Response) model. With the support of the fuzzy neural network, the eco-environment quality of Beijing in 2007 and 2015 was quantitatively assessed using different report units, e.g., county and major function oriented zone (MFOZ). The results showed that: (1) The grade of eco-environment in Beijing from high to low ranged as: far suburbs, near suburbs and downtowns. (2) The eco-environmental quality of ecological conservation development zone and prohibited development area of MFOZ was superior to other types of MFOZ. (3) The eco-environment quality grades of the northern and southwestern areas of Beijing were at level Ⅱ in 2007 and 2015, and the eco-environment quality grade in the southeastern part was gradually increasing, while the eco-environment quality in central and near suburbs of Beijing showed adeterioration trend from 2007 to 2015.

Optimization of fermentation medium composition by response surface methodology for the spore production of Bacillus subtilis.

HU Rui-ping, DING Xian, LI Lai-hao, LI Jun-wei, WU Wen-chao, XU Ning

2018, 37(2):  605-612. 

Asbtract ( 446 )   PDF (945KB) ( 218 )  

Both one factor at atime method and response surface methodology were used toenhance the spore content ofBacillus subtilis NHS1 in fermentation broth. A response surfaceregression equation was established based on the results of onefactor at atime, PlackettBurman, steepest ascent and Box-Behnken experimental designs. The optimal mediumformulation, as predicted from the equation, consisted of 1.88 g·L^-1 starch, 6.83 g·L^-1 NaCl, 5.60 g·L^-1 corn flour, 10 g·L^-1 yeast extract powder, 10 g·L^-1 peptone, 15 g·L^-1 beefextract, 2 g·L^-1 glucose, 3 g·L^-1 MgSO₄. The yield of the spore reached 2.42×10⁹cfu·mL^-1, which was 1.5fold higher than that before the optimization by using the optimized medium at36 ℃ with shaking at a speed of 170 r·min^-1 for 72 h.