Table of Content

18 March 2016, Volume 27 Issue 3

Previous Issue    Next Issue

contents

Effects of simulated warming on soil DOC and DON concentrations in the alpine forest of western Sichuan based on altitudinal gradient experiment

CHANG Chen-hui, GOU Xiao-lin, WU Fu-zhong, YANG Wan-qin, YIN Rui, XIONG Li, XIAO Sa

2016, 27(3):  663-671.  doi:10.13287/j.1001-9332.201603.019

Asbtract ( 371 )   PDF (850KB) ( 179 )  

In order to understand the effects of climate warming on the process of soil carbon and nitrogen in the alpine forest, intact soil columns were collected in the alpine fir forest, and dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations in both soil organic layer (OL) and mineral soil layer (ML) placed at different altitudes were measured from May 2010 to April 2011 (the first incubation period) and from May 2011 to April 2012 (the second incubation period). The results indicated that both DOC and DON concentrations in OL and ML va-ried greatly during the sampling period. The DOC concentration in soil columns at the altitudes of 3300 and 3000 m increased 6.8 and 26.6 mg·kg^-1 compared with that at 3600 m, respectively. The highest DOC concentrations in soil columns at the altitudes of 3600, 3300 and 3000 m were 408.0, 317.9 and 448.2 mg·kg^-1, respectively, which were all detected in LG (late growth pe-riod) during the first incubation period, while the lowest concentrations were 33.1, 32.4 and 36.5 mg·kg^-1, respectively, which were all detected in MG (mid growth period) during the second incubation period. Moreover, the DON concentration in soil columns at the altitudes of 3300 and 3000 m increased 2.3 and 30.4 mg·kg^-1 respectively compared with that at 3600 m. The highest DON concentrations at the altitudes of 3600 and 3300 m were 65.9 and 64.6 mg·kg^-1, which were both detected in MG in the first incubation period, while the lowest concentrations were 31.9 and 37.1 mg·kg^-1, both detected in ET (early thawing period) in the second incubation period. Simulated warming increased the concentrations of DOC and DON in the OL, but decreased the concentration of DOC in ML and the ratio of DOC to DON in OL and ML. The ratio of DOC to DON was significantly positively related with DOC concentration and negatively related with DON concentration in OL, whereas the ratio of DOC to DON was significantly negatively related with DOC concentration and positively with DON concentration in ML. The results indicated that climate warming would increase the concentrations of DOC and DON in soils of the high-frigid forest by changing soil tempe-rature and freeze-thaw pattern, and in turn alter the process of soil carbon and nitrogen.

Dynamics of microbial biomass carbon and nitrogen during foliar litter decomposition under artificial forest gap in Pinus massoniana plantation

ZHANG Ming-jin,CHEN Liang-hua, ZHANG Jian, YANG Wan-qin, LIU Hua, LI Xun, ZHANG Yan

2016, 27(3):  672-680.  doi:10.13287/j.1001-9332.201603.037

Asbtract ( 374 )   PDF (1042KB) ( 48 )  

Nowadays large areas of plantations have caused serious ecological problems such as soil degradation and biodiversity decline. Artificial tending thinning and construction of mixed forest are frequently used ways when we manage plantations. To understand the effect of this operation mode on nutrient cycle of plantation ecosystem, we detected the dynamics of microbial bio-mass carbon and nitrogen during foliar litter decomposition of Pinus massoniana and Toona ciliate in seven types of gap in different sizes (G₁: 100 m², G₂: 225 m², G₃: 400 m², G₄: 625 m², G₅: 900 m², G₆: 1225 m², G₇: 1600 m²) of 42-year-old P. massoniana plantations in a hilly area of the upper Yang-tze River. The results showed that small and medium-sized forest gaps(G₁-G₅) were more advantageous for the increment of microbial biomass carbon and nitrogen in the process of foliar litter decomposition. Along with the foliar litter decomposition during the experiment (360 d), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) in P. massoniana foliar litter and MBN in T. ciliata foliar litter first increased and then decreased, and respectively reached the maxima 9.87, 0.22 and 0.80 g·kg^-1 on the 180^th d. But the peak (44.40 g·kg^-1) of MBC in T. ciliata foliar litter appeared on the 90^th d. Microbial biomass carbon and nitrogen in T. ciliate was significantly higher than that of P. massoniana during foliar litter decomposition. Microbial biomass carbon and nitrogen in foliar litter was not only significantly associated with average daily temperature and the water content of foliar litter, but also closely related to the change of the quality of litter. Therefore, in the thinning, forest gap size could be controlled in the range of from 100 to 900 m² to facilitate the increase of microbial biomass carbon and nitrogen in the process of foliar litter decomposition, accelerate the decomposition of foliar litter and improve soil fertility of plantations.

Changes of soil microbial biomass carbon and their impact factors for Pinus tabuliformis plantations at different development stages on the Loess Plateau, China

QIU Tian-tian, LIU Guo-bin, WANG Guo-liang, SUN Li-peng, YAO Xu

2016, 27(3):  681-687.  doi:10.13287/j.1001-9332.201603.010

Asbtract ( 396 )   PDF (488KB) ( 156 )  

By taking an abandoned land as control and the young (13-15 year-old), middle-age (25-27 year-old) and mature (41-43 year-old) plantations of Pinus tabuliformis as research objects, the variation characteristics and impact factors of soil microbial biomass carbon (MBC) for the P. tabuliformis plantations in 0-60 cm soil layer were studied. Results showed that the average MBC at the young, middle-age and mature plantations was 93.08, 122.64 and 191.34 mg·kg^-1, respectively, which showed a significant increase with growth stage and was significantly higher than the abandoned land (42.93 mg·kg^-1). The average MBC contents gradually decreased with soil depth. Compared with the abandoned land, the average MBC at the young, middle-aged and mature plantations respectively increased by 134.2%, 221.7% and 375.7% in the 0-20 cm soil layer, 101.3%, 164.3% and 337.5% in the 20-40 cm soil layer, and 103.1%, 146.2% and 303.0% in 40-60 cm soil layer. The MBC for the whole soil layer of 60 cm had a highly significant correlation with the DBH, height and root biomass of the P. tabuliformis plantation, as well as the thickness, biomass and total nitrogen of litter. Meanwhile, the MBC also showed significant correlations with soil organic carbon (SOC), total nitrogen and moisture content. Principal component analysis showed that the root biomass, litter biomass and SOC were the principal factors affecting MBC. The P. tabuliformis plantation significantly increased SOC content mainly through litter of leaf and root and improved the MBC in the growth process.

Distribution characteristics of soil nitrogen and its influence factors in different typical zonal soils

CAO Xiao-chuang, ZHONG Chu, MA Qing-xu, ZHU Lian-feng, ZHANG Jun-hua, YU Sheng-miao, JIN Qian-yu, WU Liang-huan

2016, 27(3):  688-696.  doi:10.13287/j.1001-9332.201603.025

Asbtract ( 429 )   PDF (694KB) ( 202 )  

On the basis of field soil sampling, this paper investigated the distribution characteristics of soil different nitrogen (N) forms and its influence factors in the different typical zonal soils. The results showed that the concentrations of soil extractable total N, extractable organic N and adsorbed amino acids extracted with 0.5 mol·L^-1 K₂SO₄ significantly increased along the altitudinal gradient in the different vertical soils, and their mean concentrations were greater than that in the horizontal soils. The concentrations of soil different N forms widely varied with the soil type in the different horizontal soils. On average, the concentration of soil adsorbed amino acids was approximately 5-fold greater than that of the free amino acids, representing 21.1% of soil extractable organic N. It indicated that the soil adsorbed amino acids extracted with the strong salt solution could serve as an important form of soil organic N. Pearson correlation analysis showed that extractable total N, extractable organic N, ammonium and amino acids in vertical soils were positively correlated with soil organic matter and total N (r=0.57-0.93, P<0.05), but negatively correlated with soil pH and nitrate (r=-0.37--0.91, P<0.05). In the horizontal soils, soil extractable total N, nitrate, organic matter, total N, alkali-hydrolyzable N and cation ions (e.g. K⁺, Ca²⁺, Mg²⁺) were all positively correlated with soil pH (r=0.36-0.85, P<0.05), whereas negatively correlated with soil ammonium and amino acids (r=-0.39--0.81, P<0.05).

Evolution pattern of phytolith-occluded carbon in typical forest-soil ecosystems in tropics and subtropics, China

HE Shan-qiong, HUANG Zhang-ting, WU Jia-sen, YANG Jie, JIANG Pei-kun

2016, 27(3):  697-704.  doi:10.13287/j.1001-9332.201603.036

Asbtract ( 474 )   PDF (674KB) ( 319 )  

Samples of fresh leaves and leaf litter, as well as soils taken from 0-10 and 10-30 cm layers, were collected in four types of typical forest ecosystems both in subtropical (Phyllostachys pubescens, Pinus massoniana, Cycloba lanopsisglauca, and Cunninghamia lanceolata stands) and in tropical climates (Vatica mangachapoi, Musa basjoo, Heveabrasiliensis, and Acacia mangium stands) for measurement of PhytOC (phytolith-occluded organic carbon) contents. The phytoliths in both leaves and soil samples were extracted by a microwave digestion method and their PhytOC contents were determined by alkali dissolution-spectrophotometry method. It was found that, among the four types of subtropical forests, the PhytOC contents of leaves, litter and 0-10 cm soil layer were the highest in P. massoniana stand (230.24, 229.17 and 20.87 g·kg^-1), the lowest in P. pubescens stand (30.55, 37.37, and 3.38 g·kg^-1), and the PhytOC content of the 10-30 cm soil layer was the highest in C. glauca stand (18.54 g·kg^-1), and the lowest in P. pubescens stand (2.90 g·kg^-1). For the four tropical forests, A. mangium stand (377.66 g·kg^-1) and V. mangachapoi stand (46.83 g·kg^-1), respectively, deposited the highest and lowest contents of PhytOC in the leaves, while the highest and lowest contents of PhytOC in the litter were observed in H. brasiliensis stand (218.23 g·kg^-1) and M. basjoo stand (27.66 g·kg^-1), respectively. Also among the tropical forests, the highest PhytOC contents in the 0-10 cm and 10-30 cm soil layers were observed in A. mangium stand (23.84 and 24.90 g·kg^-1), while the lowest values occurred in M. basjoo stand (3.89 and 3.93 g·kg^-1). The PhytOC contents in transitioning from leaves to soils (0-10 cm layers) decreased by 97.4% for C. lanceolata, 94.9% for C. glauca, 90.9% for P. massoniana, and 88.9% for P. pubescens in the subtropics, and by 95.9% for H. brasiliensis, 93.7% for A. mangium, 93.3% for M. basjoo, 63.7% for V. mangachapoi in the tropics. There was no significant difference in PhytOC contents between leaves and litter for the following five forest types: P. pubescens, P. massoniana, C. lanceolata, V. mangachapoi and H. brasiliensis. However, significantly higher PhytOC contents in leaves than in litters were measured in C. glauca, M. basjoo, and A. mangium. The findings that significantly lower PhytOC contents occurred in soils than in fresh leaves and leaf litter regardless of type of forest ecosystem suggested that phytolith was not stable during the pathway from plants to soil via the forest litter.

Spatial heterogeneity and influencing factors of soil phosphorus concentration in a mid-subtropical Choerospondias axillaris deciduous broad-leaved forest, China

HU Rui-bin, FANG Xi, XIANG Wen-hua, JIANG Fang, LEI Pi-feng, ZHAO Li-juan, ZHU Wen-juan, DENG Xiang-wen

2016, 27(3):  705-715.  doi:10.13287/j.1001-9332.201603.013

Asbtract ( 369 )   PDF (1106KB) ( 161 )  

In order to investigate spatial variations in soil phosphorus (P) concentration and the influencing factors, one permanent plot of 1 hm² was established and stand structure was surveyed in Choerospondias axillaries deciduous broadleaved forest in Dashanchong Forest Park in Changsha County, Hunan Province, China. Soil samples were collected with equidistant grid point sampling method and soil P concentration and its spatial variation were analyzed by using geo-statistics and geographical information system (GIS) techniques. The results showed that the variations of total P and available P concentrations in humus layer and in the soil profile at depth of 0-10, 10-20 and 20-30 cm were moderate and the available P showed higher variability in a specific soil layer compared with total P. Concentrations of total P and available P in soil decreased, while the variations increased with the increase in soil depth. The total P and available P showed high spatial autocorrelation, primarily resulted from the structural factors. The spatial heterogeneity of available P was stronger than that of total P, and the spatial autocorrelation ranges of total P and available P varied from 92.80 to 168.90 m and from 79.43 to 106.20 m in different soil layers, respectively. At the same soil depth, fractal dimensions of total P were higher than that of available P, with more complex spatial pattern, while available P showed stronger spatial correlation with stronger spatial structure. In humus layer and soil depths of 0-10, 10-20 and 20-30 cm, the spatial variation pattern of total P and available P concentrations showed an apparent belt-shaped and spot massive gradient change. The high value appeared at low elevation and valley position, and the low value appeared in the high elevation and ridge area. The total P and available P concentrations showed significantly negative correlation with elevation and litter, but the relationship with convexity, species, numbers and soil pH was not significant. The total P and available P exhibited significant positive correlations with soil organic carbon (SOC), total nitrogen concentration, indicating the leaching characteristics of soil P. Its spatial variability was affected by many interactive factors.

Differences in soil organic carbon and total nitrogen and their impact factors under different restoration patterns in the Loess Plateau

WANG Zhi-qi, DU Lan-lan, ZHAO Man, GUO Sheng-li

2016, 27(3):  716-722.  doi:10.13287/j.1001-9332.201603.017

Asbtract ( 397 )   PDF (717KB) ( 175 )  

Knowledge of the effect of different vegetation restoration measures on soil organic carbon (SOC) and total soil nitrogen (TN) is of importance to better understand carbon and nitrogen cycling in terrestrial ecosystems and deal with the global greenhouse effect. The differences in SOC and TN content in 0-100 cm soil profile between different restoration measures and their impact factors were investigated in the Loess Plateau. The results showed that artificial vegetation restoration led to a significant increase in both SOC and TN content in the 0-100 cm soil profile compared with that of cropland. The highest increase in average SOC content was observed in the artificial woodland(1.43 times that of the cropland), followed by the artificial shrubland (1.36 times) and artificial grassland (1.21 times); whereas the highest increase in average TN content was observed in the artificial woodland (1.30 times that of the cropland), followed by the artificial grassland (1.21 times) and artificial shrubland (1.13 times). Compared with the cropland, there was a significant difference in SOC and TN content and fine root density up to a maximum depth of >100 cm in the artificial woodland and shrubland, but about 60 cm in the artificial grassland. The fine root density, soil C:N ratio and aboveground litter production of artificial woodland, shrubland and grassland were significantly higher than that of cropland, and fine root density was significantly linearly correlated with SOC and TN (P<0.01). The quantity and quality of fine root and litter biomass might be the dominant factors contributing to the observed difference in SOC and TN contents between the different artificial vegetation types in the Loess Plateau.

Effects of sand burial on fluxes of greenhouse gases from the soil covered by biocrust in an arid desert region

TENG Jia-ling, JIA Rong-liang, HU Yi-gang, XU Bing-xin, CHEN Meng-chen, ZHAO Yun

2016, 27(3):  723-734.  doi:10.13287/j.1001-9332.201603.018

Asbtract ( 352 )   PDF (2252KB) ( 166 )  

Based on the measurements of the fluxes of CO₂, CH₄ and N₂O from the soil covered by two types of biocrusts dominated separately by moss and algae-lichen, followed by 0 (control), 1 (shallow) and 10 (deep) mm depths of sand burial treatments, we studied the effects of sand burial on greenhouse gases fluxes and their relationships with soil temperature and moisture at Shapotou, southeastern edge of the Tengger Desert. The results showed that sand burial had significantly positive effects on CO₂ emission fluxes and CH₄ uptake fluxes of the soil covered by the two types of biocrusts, but imposed differential effects on N₂O fluxes depending on the type of biocrust and the depth of burial. Deep burial (10 mm) dramatically increased the N₂O uptake fluxes of the soil co-vered by the two types of biocrusts, while shallow burial (1 mm) decreased the N₂O uptake flux of the soil co-vered by moss crust only and had no significant effects on N₂O uptake flux of the soil covered by algae-lichen crust. In addition, CO₂ fluxes of the two biocrusts were closely related to the soil temperature and soil moisture, thereby increasing with the raised soil surface temperature and soil moisture caused by sand burial. However, the relationships of burial-induced changes of soil temperature and moisture with the changes in the other two greenhouse gases fluxes were not evident, indicating that the variations of soil temperature and moisture caused by sand burial were not the key factors affecting the fluxes of CH₄ and N₂O of the soil covered by the two types of biocrusts.

Spatial and temporal changes of the ecological vulnerability in a serious soil erosion area, Southern China

YAO Xiong, YU Kun-yong, LIU Jian, YANG Su-ping, HE Ping, DENG Yang-bo, YU Xin-yan, CHEN Zhang-hao

2016, 27(3):  735-745.  doi:10.13287/j.1001-9332.201603.022

Asbtract ( 362 )   PDF (3154KB) ( 402 )  

Research on eco-environment vulnerability assessment contributes to the ecological environmental conservation and restoration. With Changting County as the study area, this paper selec-ted 7 indicators including slope, soil type, multi-year average precipitation, elevation deviate degree, normalized difference vegetation index, population density and land use type to build ecological vulnerability assessment system by using multicollinearity diagnostics analysis approach. The quantitative assessment of ecological vulnerability in 1999, 2006 and 2014 was calculated by using entropy weight method and comprehensive index method. The changes of the temporal-spatial distribution of ecological vulnerability were also analyzed. The results showed that the ecological vulnerability level index (EVLI) decreased overall but increased locally from 1999 to 2014. The average EVLI values in 1999, 2006 and 2014 were 0.4533±0.1216, 0.4160±0.1111 and 0.3916±0.1139, respectively, indicating that the ecological vulnerability in Changting County was at the moderate grade. The EVLI decreased from 2.92 in 1999 to 2.38 in 2006 and 2.13 in 2014. The spatial distribution of the ecological vulnerability was high inside but low outside. The high vulnerability areas were distributed mainly in Hetian Town and Tingzhou Town, where the slope was less than 15° and the altitude was lower than 500 m. During the study period, Sanzhou Town had the largest decreasing range of EVLI while Tingzhou Town had the lowest.

Whole-tree sap flow of Quercus liaotungensis and Populus davidiana in response to environmental factors in the loess plateau area of western Shanxi Province, northern China

CHEN Bao-qiang, ZHANG Jian-jun, ZHANG Yan-ting, TIAN Ning-ning

2016, 27(3):  746-754.  doi:10.13287/j.1001-9332.201603.028

Asbtract ( 491 )   PDF (814KB) ( 128 )  

Sap flow velocity (SFV) of Quercus liaotungensis and Populus davidiana, which are two main tree species of secondary forests in the Loess Plateau area of western Shanxi Pro-vince, was measured using a thermal dissipation probe during the growing season from April to October 2012. The responses of SFV to vapor pressure deficit (VPD), photosynthetically active radiation (PAR), air temperature (T) and soil water content (θ) were investigated. The results showed that the diurnal changes of SFV of Q. liaotungensis and P. davidiana were mainly influenced by VPD and PAR in May and June, whereas VPD and T were the determining meteorological factors for the diurnal changes of SFV in July and August. Besides the meteorological factors, θ also had an important effect on SFV. The increases in θ during rainfall events resulted in the increases in SFV of both the two tree species. The average SFV of Q. liaotungensis after rainfall events was 28.3％, 48.6％, 16.9％ and 11.5％ higher than that before rainfall events in May, June, July and August, respectively. The average SFV of P. davidiana only increased, respectively, 0.6％, 4.5％ and 2.3％ after rainfall events in June, July and August. It showed that Q. liaotungensis had a higher water demand and was more sensitive to soil water condition than P. davidiana, while the latter could mana-ge its water consumption more conservatively after raining. The relationship between SFV and VPD could be approximately expressed using an exponential saturation function. The change of the parameters of the fitted exponential saturation function indicated that the SFV could quickly reach its maximum value as soil moisture increased.

Rainfall and soil moisture redistribution induced by xerophytic shrubs in an arid desert ecosystem

WANG Zheng-ning, WANG Xin-ping, LIU Bo

2016, 27(3):  755-760.  doi:10.13287/j.1001-9332.201603.029

Asbtract ( 407 )   PDF (976KB) ( 106 )  

Rainfall partitioning by desert shrub canopy modifies the redistribution of incident rainfall under the canopy, and may affect the distribution pattern of soil moisture around the plant. This study examined the distribution of rainfall and the response of soil moisture beneath the canopy of two dominant desert shrubs, Caragana korshinskii and Artemisia ordosica, in the revegetation area at the southeastern edge of the Tengger Desert. The results showed that throughfall and stemflow ave-ragely occupied 74.4%, 11.3% and 61.8%, 5.5% of the gross precipitation for C. korshinskii and A. ordosica, respectively. The mean coefficients of variation (CV) of throughfall were 0.25 and 0.30, respectively. C. korshinski were more efficient than A. ordosica on stemflow generation. The depth of soil wetting front around the stem area was greater than other areas under shrub canopy for C. korshinski, and it was only significantly greater under bigger rain events for A. ordosica. The shrub canopy could cause the unevenness of soil wetting front under the canopy in consequence of rainfall redistribution induced by xerophytic shrub.

Rainfall effects on the sap flow of Hedysarum scoparium

YANG Qiang, ZHA Than-shan, JIA Xin, QIN Shu-gao, QIAN Duo, GUO Xiao-nan, CHEN Guo-peng

2016, 27(3):  761-768.  doi:10.13287/j.1001-9332.201603.031

Asbtract ( 363 )   PDF (1315KB) ( 166 )  

In arid and semi-arid areas, plant physiological responses to water availability depend largely on the intensity and frequency of rain events. Knowledge on the responses of xerophytic plants to rain events is important for predicting the structure and functioning of dryland ecosystems under changing climate. The sap flow of Hedysarum scoparium in the Mu Us Sand Land was continuously measured during the growing season of 2012 and 2013. The objectives were to quantify the dynamics of sap flow under different weather conditions, and to examine the responses of sap flow to rain events of different sizes. The results showed that the daily sap flow rates of H. scoparium were lower on rainy days than on clear days. On clear days, the sap flow of H. scoparium showed a midday plateau, and was positively correlated with solar radiation and relative humidity. On rainy days, the sap flow fluctuated at low levels, and was positively correlated with solar radiation and air temperature. Rain events not only affected the sap flow on rainy days through variations in climatic factors (e.g., solar radiation and air temperature), but also affected post-rainfall sap flow velocities though changes in soil moisture. Small rain events (<20 mm) did not change the sap flow, whereas large rain events (>20 mm) significantly increased the sap flow on days following rainfall. Rain-wetted soil conditions not only resulted in higher sap flow velocities, but also enhanced the sensitivity of sap flow to solar radiation, vapor pressure deficit and air temperature.

Forest fire risk assessment for China under different climate scenarios

TIAN Xiao-rui, DAI Xuan, WANG Ming-yu, ZHAO Feng-jun, SHU Li-fu

2016, 27(3):  769-776.  doi:10.13287/j.1001-9332.201603.034

Asbtract ( 505 )   PDF (2124KB) ( 149 )  

Forest fire risk depends on the hazard factors, affected body, and hazard prevention and reduction ability. The integrated risk assessment is the foundation for developing scientific fire mana-gement policies and carrying out the forest fire prevention measures. A forest fire risk assessment model and index system were established based on the classic natural disaster risk model and available data, and the model was used to assess the forest fire risks in past and future. The future climate scenario data included outputs from five global climate models (GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, MIROC-ESM-CHEM and NorESM1-M) for RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5, respectively. Each component index of Fire Weather Index (FWI) system was calculated daily for each grid in 1987-2050 for the historical observations and future climate scenarios according to the maximum temperature, minimum relative humidity, wind speed and daily precipitation. The results showed that areas with high and very high fire danger ratings in 1987-2010 accounted for 21.2% and 6.2%, respectively, which were distributed in Greater Xing’an Mountains and the Changbai Mountain area, most parts of Yunnan, and many fragment areas in southern China. The areas with high and very high burn possibilities were mainly distributed in the northeast and southwest region, accounting for 13.1% and 4.0%, respectively. Compared with the observation period, the areas with high and very high fire danger ratings in 2021-2050 would increase by 0.6%, 5.5%, 2.3%, and 3.5% under RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5 respectively, and North China would show significant increase. The regions with high-risk forest fires would also increase due to climate change, with the most significant increase under RCP 8.5 scenario (+1.6%).

Relationship between retention PM₂₅ and leaf surface AFM character of six greening trees during autumn in Beijing West Mountain

CHEN Bo, LIU Hai-long, ZHAO Dong-bo, CHEN Peng-fei, LU Shao-wei, LI Shao-ning

2016, 27(3):  777-784.  doi:10.13287/j.1001-9332.201603.026

Asbtract ( 370 )   PDF (2092KB) ( 147 )  

This study investigated PM_2.5 adsorption by leaves of six tree species (Pinus bungeana, Pinus tabuliformis, Salix babylonica, Acer mono, Ginkgo biloba, Populus davidiana) in the West Mountain of Beijing. An aerosol generator was used for quantitative determination of PM_2.5 adsorption. Atomic force microscopy (AFM) was used to determine micro morphology characteristics on the leaf surface, including roughness parameters and the PM_2.5 absorption mechanism of tree leaves. The results showed that the PM_2.5 adsorption capacity per unit leaf area was as follows: P. bungeana (2.44±0.22 μg·cm^-2) > P. tabuliformis (2.40±0.23 μg·cm^-2) > S. babylonica (1.62±0.09 μg·cm^-2) > A. mono (1.23±0.01 μg·cm^-2) > G. biloba (1.00±0.07 μg·cm^-2) > P. davi-diana (0.97±0.03 μg·cm^-2). In autumn, PM_2.5 adsorption capacity per unit leaf area was as follows: November (2.33±0.43 μg·cm^-2) > October (1.62±0.64 μg·cm^-2) > September (1.51±0.50 μg·cm^-2). The leaves of P. bungeana and P. tabuliformis were rugged with many recesses and protrusions, large relative height difference, and high roughness, and their absorption ability of PM_2.5 was strong. The leaves of S. babylonica and A. mono had folded leaf lamina and were covered by fine hairs, and their roughness was relatively high, with many protrusions and fillisters on the leaf surface. Since G. biloba and P. davidiana had smooth leaves, mostly oblong stomata and low roughness, their PM_2.5 absorption ability was weaker. The ranking of average roughness on the ada-xial and abaxial side of the leaves was as follows: P. bungeana (149.91±16.38 nm) > P. tabuliformis (124.47±10.52 nm) > S. babylonica (98.85±5.36 nm) > A. mono (93.74±21.75 nm) > G. biloba (80.84±0.88 nm) > P. davidiana (67.72±8.66 nm). This accorded with PM_2.5 adsorption per unit leaf area, and leaf roughness had a significant positive correlation with PM_2.5 adsorption amount per unit leaf area as well (R²=0.9498). To improve the environmental effects of city vegetation, tree species with leaf surface morphology that facilitates absorption of PM_2.5 and other particles should be selected.

Detecting the moisture content of forest surface soil based on the microwave remote sensing technology

LI Ming-ze, GAO Yuan-ke, DI Xue-ying, FAN Wen-yi

2016, 27(3):  785-793.  doi:10.13287/j.1001-9332.201603.038

Asbtract ( 449 )   PDF (1503KB) ( 72 )  

The moisture content of forest surface soil is an important parameter in forest ecosystems. It is practically significant for forest ecosystem related research to use microwave remote sensing technology for rapid and accurate estimation of the moisture content of forest surface soil. With the aid of TDR-300 soil moisture content measuring instrument, the moisture contents of forest surface soils of 120 sample plots at Tahe Forestry Bureau of Daxing’anling region in Heilongjiang Province were measured. Taking the moisture content of forest surface soil as the dependent variable and the polarization decomposition parameters of C band Quad-pol SAR data as independent variables, two types of quantitative estimation models (multilinear regression model and BP-neural network model) for predicting moisture content of forest surface soils were developed. The spatial distribution of moisture content of forest surface soil on the regional scale was then derived with model inversion. Results showed that the model precision was 86.0% and 89.4% with RMSE of 3.0% and 2.7% for the multilinear regression model and the BP-neural network model, respectively. It indicated that the BP-neural network model had a better performance than the multilinear regression model in quantitative estimation of the moisture content of forest surface soil. The spatial distribution of forest surface soil moisture content in the study area was then obtained by using the BP neural network model simulation with the Quad-pol SAR data.

Effects of different disturbance types on plant species composition and functional group cha-racteristics of typical steppe in Inner Mongolia, China

YANG Yong, LIU Ai-jun, LI Lan-hua, WANG Bao-lin, WANG Ming-jiu

2016, 27(3):  794-802.  doi:10.13287/j.1001-9332.201603.007

Asbtract ( 337 )   PDF (571KB) ( 175 )  

The impacts of three kinds of human disturbances, i.e., non-grazing, reseeding and free-grazing, on plant community characters, i.e., species composition, composition of functional groups, species diversity, and aboveground biomass, were studied in a typical steppe in Inner Mongolia, China. The results showed that different disturbances had significant impacts on the structure and diversity of plant functional groups. The number of plant species, aboveground biomass, community diversity, and richness indices were the highest in the non-grazing treatment, with the fi-gures of 22, 171.32 g·m^-2, 1.46 and 5.7, respectively. The importance value (IV), percentage, aboveground biomass, diversity, richness, and evenness indices of shrub and sub-shrub, and perennial grasses were also the highest in the non-grazing treatment. In contrast, the IV, species percentage, aboveground biomass, diversity, and evenness indices of perennial forbs were the lowest in the non-grazing treatment. The aboveground biomass of mesophyte, C3 and C4 plants was the highe-st with the figures of 22.22, 143.35 and 27.97 g·m^-2 respectively in the non-grazing treatment. The aboveground biomass of mesoxerophyte was highest (13.60 g·m^-2), the species percentage of xerophyte was lowest (48.5%) and that of C4 plants was highest (28.8%) in the reseeding treatment. The species percentage of annual or biennial herbs was highest (12.3%), while that of mesophyte and C4 plants was lowest (17.0% and 20.9%) in the free-grazing treatment. The non-grazing treatment showed a beneficial effect for restoration of degraded grassland system.

Projected changes in vegetation net primary productivity of grassland in Inner Mongolia, China during 2011-2050

GUO Ling-hui, HAO Cheng-yuan, WU Shao-hong, GAO Jiang-bo, ZHAO Dong-sheng

2016, 27(3):  803-814.  doi:10.13287/j.1001-9332.201603.011

Asbtract ( 403 )   PDF (3244KB) ( 190 )  

In this paper, the CENTURY-based modeling system (complying CENTURY model from a site-based model into spatial model) after being systematically calibrated was used to investigate future climate change under Representative Concentration Pathways Scenario (RCP, 4.5 and 8.5) driven spatio-temporal changes in vegetation net primary productivity (NPP) of Inner Mongolia grassland during 2011-2050. The simulation showed that Inner Mongolia grassland NPP would greatly decrease with a rate of 0.57 g C·m^-2·a^-1 (RCP4.5) and 0.89 g C·m^-2·a^-1 (RCP8.5). NPP of Inner Mongolia grassland appeared to decrease by approximately 11.6% (2020s), 12.0% (2030s) and 18.0% (2040s) under the RCP4.5 in relation to baseline period, while its reduction could be exacerbated as 23.8% (2020s), 21.2% (2030s) and 30.1% (2040s) in the RCP8.5 at the regional scale. In addition, grassland NPP induced by future climate changes varied between different grassland types and times, strongly correlating with climate scenario. Even for the RCP4.5, however, a great majority (89.7%) of the grassland exhibited a decreasing trend in annual NPP, with 15.6% of the area decreasing by more than 20% compared with the baseline term. Therefore, although future precipitation rising could benefit vegetation growth, it might be still not enough to compensate for the negative effect of warming on the NPP of Inner Mongolia grassland, and the sustainable development of grassland resources might face a greater challenge.

Herb diversity and its affecting factors of community invaded by Praxelis clematidea in karst mountainous area of Guangxi Province, China

HUANG Xiao-rong, PANG Shi-long, SHEN Wen-hui, HOU Yuan-rui, HE Feng

2016, 27(3):  815-821.  doi:10.13287/j.1001-9332.201603.016

Asbtract ( 426 )   PDF (523KB) ( 138 )  

Community invaded by Praxelis clematidea in karst mountainous area of Pingguo, Guangxi Province was investigated including 4 land types, i.e. abandoned cropland, young plantation, roadside and shrub. Meta analysis, analysis of covariance, linear mixed effect model and recursive partitioning were used to analyze their herb diversity and richness in relation to environmental variables. The results showed that summary effects were positive and significant, effects of groups were positive, effect of abandoned cropland was negative, and effects of other three land types were positive, and shrub had high weight in the analysis. Analysis of covariance indicated that importance value of P. clematidea, distance to driveway and soil were the main numeric factors influencing herb diversity and herb species richness, and plots invaded had higher herb diversity and richness than those uninvaded. Land types had extremely significant impacts on herb diversity but had nothing on herb species richness. Linear mixed effect model partitioned the explained variances of random effects, factor P. clematidea present or absent and residuals respectively contributed 50.9% and 49.1% in Shannon model, while 39.0% and 61.0% in richness model, groups and land types contributed zero to the random effects. P. clematidea invasion could be classified into 5 levels, and modest invasion caused higher herb diversity and richness. When P. clematidea importance value was more than 23.6%, the critical threshold, both herb diversity and richness declined.

Impacts of organic and inorganic fertilizations on alfalfa yield, soil nitrate and greenhouse gas emissions

YANG Yuan-yuan, GAO Zhi-ling, WANG Xue-jun

2016, 27(3):  822-828.  doi:10.13287/j.1001-9332.201603.021

Asbtract ( 440 )   PDF (969KB) ( 102 )  

Field plot experiment was carried out during May 2012 to June 2014 to investigate the impacts of nitrogen fertilizations on the emissions of nitrous oxide (N₂O) and methane (CH₄) from alfalfa field as well as the dry matter yield and soil nitrate contents. Five treatments including CK, urea (100 kg N·hm^-2, CF), urea (100 kg N·hm^-2) + dairy cattle manure (60 kg N·hm^-2) (DM₁), urea (100 kg N·hm^-2)+ digestate (60 kg N·hm^-2) (DT) and reduced urea (40 kg N·hm^-2)+ dairy cattle manure (60 kg N·hm^-2) (DM₂) were conducted. Results indicated that in comparison with CK, CF, DM₁, DT and DM₂ treatments significantly increased the dry matter yields of alfalfa by 44.2%, 38.9%, 56.3% and 30.6%, and increased the N₂O emissions by 52.2%,89.1%, 133.7% and 59.4%, respectively, whereas the oxidation of atmospheric CH₄ was reduced to different extents by these N management practices. The losses of N₂O-N originated from urea and dairy cattle manure N accounted for 0.25%-0.28% of their inputs, whereas a greater va-lue of 0.64% was observed for digestate N. Applying urea or organic N to alfalfa field could significantly increase the dry matter yield without significant NO₃^--N leaching, however, it would lead to higher net CO_2-equivalent emissions of producing 1 t dry matter of alfalfa.

Effects of bio-organic fertilizer on soil enzyme activities and microbial community in kiwifruit orchard

SUN Jia-jun, FU Qing-xia, GU Jie, WANG Xiao-juan, GAO Hua

2016, 27(3):  829-837.  doi:10.13287/j.1001-9332.201603.012

Asbtract ( 364 )   PDF (799KB) ( 268 )  

A field experiment was conducted to compare the effects of three fertilizer managements (bio-organic fertilizer, traditional organic fertilizer and chemical fertilizer) and a no-fertilizer control on soil enzyme activities and microbial community functional diversity in a kiwifruit orchard. The results showed that the soil invertase and FDA hydrolase activities in the bio-organic fertilizer treatment were 12.2%-129.4% and 18.8%-87.4% higher than those in the no-fertilizer control during kiwifruit growth period, respectively. The application of bio-organic fertilizer also increased soil urease and acid phosphatase activities at the expanding stage and maturity stage. The Biolog results suggested that bio-organic fertilizer treatment improved the average well color development (AWCD) and increased the species diversity, richness and evenness. The relative ratios of six groups of carbon sources by microbes were changed to some extent after the application of bio-organic fertilizer. Compared with the no-fertilizer control, bio-organic fertilizer application decreased the capacity of microbes in using amino acids, but enhanced the utilization of polyphenols and polyamines. The principal components analysis demonstrated that the differentiation of microbial community was mainly in utilization of carbohydrates, amino acids and carboxylic acids.

Resource surveys and suitability of origin for genuine medicinal materials, Astragalus membranaceus var mongholicus in Inner Mongolia, China

LIU De-wang, GU Cai-mei, YANG Qing-zhen, HUANG Lin-fang, XIE Cai-xiang, CAI Min

2016, 27(3):  838-844.  doi:10.13287/j.1001-9332.201603.035

Asbtract ( 465 )   PDF (1599KB) ( 332 )  

In order to explore the ecological factors affecting the growth of Astragalu smembranaceus var. mongholicus, we investigated the resource distribution, habitat characteristics and growth conditions of wild and cultivated A. membranaceus var. mongholicus by fixed-plot observation, survey method, and literature. These data were analyzed by traditional Chinese medicine GIS-Ⅱ (TCMGS-Ⅱ) to obtain the most suitable areas of A. membranaceus var. mongholicus within Inner Mongolia. The results showed that the production areas of cultivated A. membranaceus var. mongholicus were mainly located in Wuchuan County, Guyang County and other 15 counties, which were cha-racterized by the altitude higher than 1000 m, with soil type of sand, gravel and calcareous clay. The wild A. membranaceus var. mongholicus was distributed mainly in the eastern Inner Mongolia and germinated in sunny place, which preferred to the cold dry climate and sandy loam soil or gra-vel but avoided damp heavy clay soils. There are 43 counties of 94460.30 km² for wild A. membranaceus var. mongholicus, and 32 counties of 76013.93 km² for cultivated one within Inner Mongolia, with a similarity coefficient of ecological factors greater than 95%.

Coupling effect of water and nitrogen on mechanically harvested cotton with drip irrigation under plastic film in arid area of western Inner Mongolia, China

LI Yong, WANG Feng, SUN Jing-sheng, LIU Hao, YANG Jian-qiang, XIAN Feng, SU He

2016, 27(3):  845-854.  doi:10.13287/j.1001-9332.201603.008

Asbtract ( 388 )   PDF (691KB) ( 170 )  

In order to understand the main and interactive effects of water and nitrogen on crop growth and development, yield, fiber quality, and water-nitrogen use efficiency of mechanically harvested cotton with drip irrigation under plastic film in arid area of western Inner Mongolia, a two-factorial experiment with irrigation water amount and nitrogen dosage in completely randomized block design was conducted in Alxa Left Banner of Alxa League in Inner Mongolia. The levels of water irrigation were 216 mm (W₁), 288 mm (W₂) and 360 mm (W₃), and the nitrogen dosages were 127.5 kg·hm^-2(N₁), 195 kg·hm^-2(N₂) and 262.5 kg·hm^-2(N₃). The results showed that water was the decisive factor for cotton growth, and plant height and dry matter accumulation increased rapidly with increasing the water irrigation level, but the ratio of reproductive organs to shoot biomass decreased. Compared with the treatments W₁ and W₂, the average boll number per plant in W₃ was increased by 25.4% and 17.5%, the seed cotton yield was improved by 18.1% and 11.9%, but the single boll mass was decreased by 5.8% and 4.6%, respectively. It indicated that an increase in boll number per plant was the determining factor in achieving high seed cotton yield. Moreover, there was also a significant interactive effect between water and nitrogen affecting the seed cotton yield. Under the condition with low-level irrigation (W₁ and W₂), the highest seed cotton yield was measured in N₁; while for the condition in W₃, the seed cotton yield in N₂ was greater than that in N₁ and N₃ by 8.5% and 31.9%, respectively. In general, the regulation of water and nitrogen had no significant effect on fiber quality. Water use efficiencyin W₁N₁ was 1.37 kg·m^-3, which was not significantly different with the value in W₃N₂, and the nitrogen partial factor productivityin W₃N₁ was the maximum (51.35 kg·kg^-1). Therefore, irrigation had a significant effect on yield increasing, but nitrogen application promoted the seed cotton yield only under well-watered conditions. The treatment with irrigation amount of 360 mm and nitrogen fertilizer of 195 kg·hm^-2 could promote the shoot biomass accumulation significantly and achieve the highest seed cotton yield, and its water use efficiency and nitrogen partial factor productivity were 1.37 kg·m^-3 and 36.41 kg·kg^-1, respectively, indicating the potential of water-saving and yield increasing. Therefore, it was recommended as a suitable water and nitrogen management for the mechanically harvested cotton in arid area of western Inner Mongolia.

Effects of ridge-cultivation and plastic film mulching on root distribution and yield of spring maize in hilly area of central Sichuan basin, China

ZHA Li, XIE Meng-lin, ZHU Min, DOU Pan, CHENG Qiu-bo, WANG Xing-long, YUAN Ji-chao, KONG Fan-lei

2016, 27(3):  855-862.  doi:10.13287/j.1001-9332.201603.023

Asbtract ( 372 )   PDF (572KB) ( 187 )  

A field experiment was conducted to study the effects of planting pattern (ridge culture, flatten culture, furrow culture) and film mulching on the distribution of spring maize root system and their influence on the yield of spring maize in the hilly area of central Sichuan basin. The results showed that ridge and film mulching had great influence on root morphology and root distribution of maize. The root length, root surface area and root volume of film mulching was 42.3%, 50.0%, 57.4% higher than those of no film mulching at jointing stage. The film mulching significantly increased the dry mass of root in vertical and horizontal distribution, and increased the root allocation ratio in deeper soil layer (20-40 cm) and the allocation ratio of wide row (0-20 cm) in horizontal direction. The effects of planting pattern on root growth and root distribution differed by film mulching. With film mulching, the ridge culture significantly increased the root dry mass in each soil layer and enlarged the distribution percentage of wide row (20-40 cm) in horizontal direction, as well as the dry mass of root in horizontal distribution and the root allocation ratio of wide row. The root mass under film mulching was in the order of ridge culture>flatten culture>furrow culture. Without film mulching, the furrow culture significantly increased root dry mass of narrow row (0-40 cm), and the root mass under no film mulching was in the order of furrow culture > ridge culture >flatten culture. As for the spike characteristics and maize yield, the filming mulching mea-sures reduced the corn bald length while increased the spike length, grain number, 1000-grain mass and yield. The yield under film mulching was in the order of ridge culture>flatten culture> furrow culture, while it was furrow culture > flatten culture > ridge culture under no film mulching. The reason for yield increase under ridge culture with film mulching was that it increased root weight especially in deep soil, and promoted the root allocation ratio in deeper soil and wide row (20-40 cm) in horizontal direction. The ridge-furrow culture without film mulching was helpful to root growth and increased the maize yield.

Effects of reduced nitrogen application and supplemental irrigation on photosynthetic characteristics and grain yield in high-yield populations of winter wheat

ZHANG Ke-ke, ZHOU Su-mei, ZHANG Man, SHI Shan-shan, YIN Jun

2016, 27(3):  863-872.  doi:10.13287/j.1001-9332.201603.006

Asbtract ( 357 )   PDF (900KB) ( 145 )  

A field experiment was conducted to study the effects of reduced nitrogen application and supplemental irrigation on the light environment, photosynthetic characteristics and yield components in high-yield wheat population. The treatments included three irrigation schedules [no irrigation (W₁), medium irrigation (W₂, the soil relative water content of 70%±5% after jointing stage), well-irrigation (W₃, the soil relative water content of 85%±5% after jointing stage)] and three nitrogen application levels [no nitrogen (N₁), reduced nitrogen (N₂,195 kg N·hm^-2), high nitrogen (N₃, 270 kg N·hm^-2)]. The results indicated that the N₂W₂ treatment significantly improved the light environment of high-yield wheat populations, the photosynthetically active radiation (PAR) and the light transmission rate at the region of 20-30 cm canopy increased by 34.5% and 10.8%, respectively, when compared with the high nitrogen-supplementary water treatments (N₃W₂, N₃W₃). The leaf area index (LAI) of N₂W₂ was the highest among all treatments tested, which decreased slowly at grain filling stage, and the period with higher LAI value (>7.6) was 3-4 days longer than that of high-nitrogen and non-nitrogen treatments, as well as, the leaf photosynthetic potential was increased by 9.7% on average. Under the treatments of N₂W₂ and N₂W₃, the photosynthetic rate (P_n) was relatively higher at grain-filling stage, while the difference was not significant compared with the treatment of N₃W₂. The apparent quantum yield in flag leaves of N₂W₂ reached 0.1 μmol CO₂·m^-2·s^-1, P_n value kept on the level of 27.692 μmol CO₂·m^-2·s^-1 and the light compensation point (LCP) was relatively lower, which demonstrated a stronger photosynthetic productivity. The grain yield of N₂W₂ was the highest among all treatments.

Effects of different fertilization patterns on soil enzyme activities in greenhouse vegetable field

WANG Wen-feng, LI Chun-hua, HUANG Shao-wen, GAO Wei, TANG Ji-wei

2016, 27(3):  873-882.  doi:10.13287/j.1001-9332.201603.015

Asbtract ( 345 )   PDF (921KB) ( 199 )  

A fixed-site greenhouse vegetable fertilization experiment was carried out to study effects of 6 fertilization patterns on soil enzyme activities in Tianjin City, Northern China. The results showed that during the growing stages of tomato, activities of soil α-glucosidase, β-xylosidase, β-glucosidase, β-cellobiosidase, chitinase and phosphatase in different treatments all increased first and then decreased, while soil urease activities increased first and then became flat. Compared with the chemical nitrogen fertilizer treatment, soil enzyme activities were much higher in treatments of combined application of organic materials with chemical fertilizers, and rose with the increasing input of pig manure and especially the application of straw. A significant positive correlation was found between soil enzyme activities, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) contents at different growing stages of tomato. Under the condition of same nutrient input, the combined application of inorganic fertilizers with organic materials, especially a certain amount of corn straw, was capable of increasing soil enzyme activities and keeping soil fertility and sustainability in greenhouse vegetable production.

Effects of fertilizer application on water consumption characteristics and yield of potato cultured under ridge-furrow and whole filed plastic mulching in rain-fed area

YU Xian-feng, ZHANG Xu-cheng, WANG Hong-li, MA Yi-fan, HOU Hui-zhi, FANG Yan-jie

2016, 27(3):  883-890.  doi:10.13287/j.1001-9332.201603.027

Asbtract ( 352 )   PDF (757KB) ( 125 )  

Chemical fertilizer reduction and organic manure substitution are the useful methods to increase potato water-and nutrient use efficiency, which is cultured under ridge-furrow and whole soil surface mulched by plastic film in semiarid rain-fed area. A 4-year field experiment was carried out from 2011 to 2014 with three treatments: 1) traditional chemical fertilizer application (F), 2) chemical nitrogen fertilizer reduced by 25% and dressing at flowering stage (DF), and 3) chemical nitrogen fertilizer reduced by 50% and organic manure substitution (OF). The soil moisture and potato yield were investigated, and seasonal water consumption, water use efficiency (WUE) were calculated to study the regulations of different nutrient management methods on potato water use process, as well as its effects on potato tuber yield and WUE. The results showed that soil water storage in potato flowering stage was the highest under DF treatment, but there were no significant difference among these three treatments. The depth of soil water depletion in DF and OF showed an increasing trend at post-flowering stage. Potato water consumption decreased significantly at pre-flowering stage, but increased by 36.2%, 23.2%, 24.8% and 19.0% respectively at post-flowering stage in 2011-2014 under DF treatment, as compared with those under F treatment. OF treatment increased potato water consumption by 20.7% and 16.3% than that under F treatment at post-flowering stage from 2011 to 2012, respectively, but exerted no significant effect at pre-flowering stage. Compared with F, DF increased potato tuber yield averagely by 2595.1 kg·hm^-2 from 2012 to 2014 and significantly increased the WUE by 14.4% and 6.3% in 2013 and 2014, respectively; OF significantly increased potato tuber yield averagely by 2945 kg·hm^-2 tuber yield in 4 experimental years and WUE was significantly higher than that under F from 2012 to 2014. It was indicated that both DF and OF could regulate water consumption between pre-flowering and post-flowering stages, and increase potato tuber yield and WUE. OF showed more significant effects than DF on the increment of tuber yield and WUE.

Effects of alkaline fertilizer on cadmium content in rice and paddy soil

ZHANG Liang-liang, FAN Xiao-lin, ZHANG Li-dan, LIU Fang

2016, 27(3):  891-896.  doi:10.13287/j.1001-9332.201603.004

Asbtract ( 338 )   PDF (489KB) ( 136 )  

A field plot trial was conducted at Songbai Village, Chenzhou, Hunan Province to exa-mine the effects of alkaline fertilizer with and without combination application of bacterial regent on cadmium accumulation in rice and paddy soil. Compared with the conventional fertilizer, the alkaline fertilizer reduced the available cadmium content in soil at the tillering, filling and the harvest stages by 8.3%, 6.7% and 16.4% respectively. Compared with the Cd content in soil before transplanting, it was reduced by 7.2% at harvest time in alkaline fertilizer treatment, while increased by 11.0% in the conventional fertilizer treatment. The available cadmium content in soil was increased by 1.2% to 23.3% by bacterial regent. Compared with the conventional fertilizer, the cadmium content of root, stem sheath, leaf, grain and brown rice of the alkaline fertilizer treatment reduced by 54.9%, 56.6%, 41.8%, 62.7% and 67.6% respectively. The alkaline fertilizer treatment combined with bacterial regent increased the cadmium content of brown rice by 63.2%. It was concluded that the alkaline fertilizer could significantly reduce the available cadmium content in both soil and the different organs of the rice, however, when it was combined with bacterial regent together, the effect of alkaline fertilizer to reduce Cd content of brown rice would be declined.

Effect of exogenous melatonin on physiological and biochemical characteristics of cucumber radicles under p-hydroxybenzoic acid

SUN Sha-sha, GONG Biao, WEN Dan, WANG Xiu-feng, WEI Min, YANG Feng-juan, LI Yan, SHI Qing-hua

2016, 27(3):  897-903.  doi:10.13287/j.1001-9332.201603.003

Asbtract ( 441 )   PDF (1499KB) ( 169 )  

‘Jinyan No. 4’cucumber was used as experimental material. The growth of cucumber radicles treated with different concentrations of p-hydroxybenzoic acid (0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5 and 20 mmol·L^-1) was investigated firstly, and 10 mmol·L^-1 p-hydroxybenzoic acid was chosen for the further experiment. To investigate if melatonin alleviate p-hydroxybenzoic acid stress on cucumber radical elongation, 0, 1, 10, 25, 50, 75 and 100 μmol·L^-1 melatonin were used to pretreat cucumber seeds for 24 h before 10 mmol·L^-1 p-hydroxybenzoic acid treatment. The results suggested that exogenous melatonin could alleviate the radicle growth inhibition induced by p-hydroxybenzoic acid, and 75 μmol·L^-1 melatonin showed the best effect. The growth of cucumber radical was significantly inhibited with an increase in p-hydroxybenzoic acid concentration, which was accompanied with lower activity of amylase. The melatonin pretreatment could significantly increase the activities of amylase and antioxidant enzymes in cucumber seeds resulting in lower accumulation of O₂^-·, H₂O₂ and MDA. Exogenous melatonin effectively reduced the PHBA stress on cucumber germination, which might be due to its function in decreasing oxidative stress and promoting starch catabolism.

Variation of rhizosphere environmental factors of sugarbeet seedlings under Na₂CO₃ stress and their correlation

GUO Jian, LI Cai-feng, LIU Lei, SANG Li-min, CHEN Ming, XU Ying, GAI Zhi-jia, WANG Yu-bo

2016, 27(3):  904-910.  doi:10.13287/j.1001-9332.201603.001

Asbtract ( 318 )   PDF (684KB) ( 136 )  

To study the effect of saline-alkali stress on dry mass, rhizosphere soil enzyme activities and soil microbial quantities, pot experiments were designed two sugar beet varieties, ‘KWS0143’ (strong tolerance to saline-alkali) and ‘Beta464’ (weak tolerance to saline-alkali) planted in different Na₂CO₃ concentrations [0% (control), 0.4%, 0.8% and 1.2% of soil], and the dry mass of seedlings,soil enzyme activities and amount of microbiology in soil were recorded. The results showed that compared with the control, the dry mass of seedlings was significantly increased in the treatment of 0.4% Na₂CO₃, while it was significantly decreased in the 0.8% and 1.2% Na₂CO₃ treatments. Significant differences among treatments were observed. The soil urease, alkali phosphatase and peroxidase activities in the root rhizosphere of seedlings presented a similar tendency under different concentrations of Na₂CO₃. Compared with the control, the enzyme activities with the treatment 0.4% Na₂CO₃ were not significantly enhanced, while those in the treatment of 0.8% and 1.2% Na₂CO₃ were significantly reduced. All the soil enzymes’ activities in ‘KWS0143 were higher than in ‘Beta464’. The 0.4% Na₂CO₃ did not lead to significant change of soil microbial community, but 0.8% and 1.2% Na₂CO₃ sharply decreased the amount of soil bacteria, fungi and actinomycets (P<0.05). The amount of rhizosphere soil microbe in ‘KWS0143’ was higher than in ‘Beta464’. There were significantly positive correlation among the dry mass, soil enzymes and soil microbe of the two varietie. Path coefficient analysis showed the determinant coefficient of ‘KWS0143’ dry mass was in order of sctinomycetes > bacteria > peroxidase > urease > fungi > alkali phosphatase, while that ‘Beta464’ dry mass was in order of actinomycetes > peroxidase > urease > fungi > alkali phosphatase > bacteria.

Influencing factors of non-point source pollution of watershed based on boosted regression tree algorithm

YIN Cai, LIU Miao, SUN Feng-yun, LI Chun-lin, XIANG Wei-ning

2016, 27(3):  911-919.  doi:10.13287/j.1001-9332.201603.020

Asbtract ( 537 )   PDF (1575KB) ( 202 )  

Non-point source (NPS) pollution has become a key water pollution problem under the condition of point source pollution was controlled. The complexity and uncertainty research of NPS pollution influential factors has always been important and difficult. This paper simulated NPS pollution of the Fanhe River watershed in 2003-2012 by the soil and water assessment tool (SWAT) and analyzed its spatial distribution. Meanwhile, the boosted regression tree (BRT) method was proposed to quantitatively analyze the corresponding influential factors including land use, soil, elevation and slope. The results showed that NPS pollution in the Fanhe River watershed had high spatial heterogeneity. The spatial distribution of total nitrogen (TN) had greater difference than that of total phosphorus (TP). The three pollutants, TN, TP and sediment, were all positively related to slope gradients (P<0.01). The slope gradients played the strongest role in determining the sediment and TP output with the contribution rate of 46.5% and 38.2%, respectively. Land use had important influence on sediment and TP loads, with the contribution rate of 27.2% and 35.3%, respectively. TN was produced abundantly in low-elevation and steep-slope locations and with cultivated land use. Cinnamon soil was most vulnerable to the TN load while meadow soil took the second place in terms of soil erosion and TP load. The paper overcame the complexity of influential factors for NPS pollution by BRT, and deepened the understanding of NPS pollution mechanism.

Analysis of grey correlation between energy consumption and economic growth in Liaoning Province, China

WANG Li, XI Feng-ming, WANG Jiao-yue

2016, 27(3):  920-926.  doi:10.13287/j.1001-9332.201603.024

Asbtract ( 380 )   PDF (629KB) ( 109 )  

The contradiction between energy consumption and economic growth is increasingly prominent in China. Liaoning Province as one of Chinese heavy industrial bases, consumes a large amount of energy. Its economic development has a strong dependence on energy consumption, but the energy in short supply become more apparent. In order to further understand the relationship between energy consumption and economic growth and put forward scientific suggestions on low carbon development, we used the greycorrelation analysis method to separately examine the relevance of economic growth with energy consumption industries and energy consumption varieties through analy-sis of energy consumption and economic growth data in Liaoning Province from 2000 to 2012. The results showed that the wholesale and retail sector and hotel and restaurant sector were in the minimum energy consumption in all kinds of sectors, but they presented the closest connection with the economic growth. Although industry energy consumption was the maximum, the degree of connection between industry energy consumption and economic growth was weak. In all types of energy consumption, oil and hydro-power consumption had a significant connection with economic growth. However, the degree of connection of coal consumption with economic growth was not significant, which meant that coal utilization efficiency was low. In order to achieve low carbon and sustainable development, Liaoning Province should transform the economic growth mode, adjust industry structure, optimize energy structure, and improve energy utilization efficiency, especially promote producer services and develop clean and renewable energy.

Community structure of macrozoobenthos and its relationship with environmental factors in Lake Gehu, Jiangsu, China

XIONG Chun-hui, ZHANG Rui-lei, JI Gao-hua, FENG Li-hui,WANG Li-qing

2016, 27(3):  927-936.  doi:10.13287/j.1001-9332.201603.039

Asbtract ( 395 )   PDF (855KB) ( 213 )  

A survey on macrozoobenthos was conducted seasonally and 14 aquatic physicochemical parameters were monitored monthly to reveal the community characteristics of macrozoobenthos and their relationship with aquatic environmental factors at 20 sampling sites in the Lake Gehu from July 2013 to December 2014. A total of 25 macrozoobenthos species including 3 species (12% of total) of Mollusca, 12 species (48%) of Chironomidae, 4 species (16%) of Oligochaeta, 4 species (16%) of Crustacean were identified. The dominant species were Limnodrilus hoffmeisteri, Branchiuras owerbyi, Tanypus chinensis, and Propsilocerus taihuensis. Density and biomass of Chironomid larvae and Oligochata had significant spatial and seasonal changes. The state of aquatic environment was mainly affected by the nitrogen, phosphorus and water temperature in the Lake Gehu, and TN, NO₃^--N and DO changed significantly with space and season. The Spearman correlation analysis indicated that TN and NO₃^--N played a key role in the community structure characteristics of the macrozoobenthos in the Lake Gehu. The environmental variables could well explain the changes of main macrobenthic species.

Feeding habits of Solenocera melantho in the northern East China Sea

LI Hui-yu, JIN Yan, LI Sheng-fa

2016, 27(3):  937-945.  doi:10.13287/j.1001-9332.201603.005

Asbtract ( 446 )   PDF (732KB) ( 159 )  

The feeding habits of the mud shrimp Solenocera melantho were determined based on the analysis of 720 stomach contents sampled in the northern East China Sea during June 2009 and May 2010. The diet of the specimens was studied in relation to the season, sex, size class and reproductive condition. The diet of S. melantho consisted of 43 different prey categories, which belonged to small crustaceans, protozoa, polychaetes, algae, fishes and molluscs. Among these, crustaceans, foraminifera and polychaetes made up the main diet of S. melantho with 34.7%, 29.4% and 12.4% in abundance, respectively. Diet composition showed seasonal fluctuation and ontogenetic change. The predominant prey was foraminifera, algae and invertebrate eggs in spring, foraminifera, fishes and polychaetes in summer and autumn, and polychaetes and foraminifera in winter. The feeding intensity was high in spring and summer, and low in autumn. The small size group (<24 mm CL) tended to like foraminifera and algae, while the large size group (≥24 mm CL) preferred polychaetes and crustaceans. Females with advanced ovaries also displayed low stomach fullness, suggesting that feeding activity was affected by the reproductive cycle. S. melantho displayed a high food niche in both sexes and each season, which could be attributed to the fluctuations in available resources. The average trophic level of the S. melantho in four seasons was 2.67, indicating that the species in the northern East China Sea was of low-level carnivores.

Combined effects of 24-epibrassinolide and salinity on the growth and physiological perfor-mance of Ulva prolifera

WANG Dong, LI Ya-he, XU Nian-jun, XU Xiao-ting

2016, 27(3):  946-#REF.  doi:10.13287/j.1001-9332.201603.032

Asbtract ( 357 )  

In order to study the combined effects of brassinosteroids and salinity on the growth and physiological performance of Ulva prolifera under low temperature condition, we investigated the growth, chlorophyll content, chlorophyll fluorescence parameters, soluble protein and carbohydrate contents in this algae, which was grown under three salinity in the presence or absence of 24-epibrassinolide. The results showed that, compared to control salinity (25) treatment, the growth rate of U. prolifera was enhanced by 45.9% under the moderate hyposaline condition (10), but decreased under low salinity (5) treatment, which showed high contents of chlorophyll and soluble protein. However, the presence of EBR (0.2 mg·L^-1) significantly reduced the growth of U. prolifera, especially under the control salinity (25) treatment, under which the fresh mass decreased and more spores were released. Additionally, the effective quantum yield (F_v′/F_m′), the activity of SOD and the content of soluble carbohydrate also decreased, but the soluble protein content increased under the control salinity treatment in the presence of EBR. In conclusion, moderatehypo-saline condition could be used to enhance the growth of U. prolifera at 15 ℃, and under normal salinity (25), the EBR could be used to promote the release of spores and produce more materials for mass production of U. prolifera.

Growth characteristics of Porites lutea skeleton in east sea area of Hainan Island, China and main affecting environmental factors

JIANG Qiao-wen, CAO Zhi-min, WANG Dao-ru, LI Yuan-chao, NI Jian-yu

2016, 27(3):  953-962.  doi:10.13287/j.1001-9332.201603.009

Asbtract ( 392 )   PDF (1422KB) ( 22 )  

The growth characteristics of Porites lutea skeleton in east sea area of Hainan Island were studied by CoralXDS software based on X-ray chronology. The growth parameters obtained included extension rate (ER), skeleton density (D), and calcification rate (CR). The results showed that ER varied from 0.49 to 1.10 cm·a^-1 with an annual average of 0.76 cm·a^-1, D varied from 1.11 to 1.35 g·cm^-3 with an annual average of 1.22 g·cm^-3, and CR varied from 0.55 to 1.41 g·cm^-2·a^-1 with an annual average of 0.94 g·cm^-2·a^-1. Statistical analyses indicated that sea surface temperature (SST) was the key environmental factor that controlled the growth characteristics, as it highly co-varied with ER and CR, less so with D. All of the three growth characteristics increased with the increase of SST. There were other factors that influenced the growth characteristics of the coral column, such as light, water salinity, and hydrodynamics, etc. In addition, typhoon and severe tropical storms also imposed a significant impact on the growth pattern of Porites lutea coral. The change in growth pattern of coral skeleton in east of Hainan Island was a response to complex climate fluctuation. Over the past century, SST of east Hainan Island dramatically increased at a rate of 0.15 ℃·(10 a)^-1. The SST increase trend for the oceanic region could be divided into two stages, early 1940s and early 1980s. The human activities and global warming was the main causes for the increase of SST.

reviews

Understory effects on overstory trees: A review

DU Zhong, CAI Xiao-hu, BAO Wei-kai, CHEN Huai, PAN Hong-li

2016, 27(3):  963-972.  doi:10.13287/j.1001-9332.201603.033

Asbtract ( 431 )   PDF (871KB) ( 105 )  

Plant-plant interactions play a key role in regulating the composition and structure of communities and ecosystems. Studies of plant-plant interactions in forest ecosystems have traditionally concentrated on either tree-tree interactions or overstory species’ impacts on understory plants. The possible effects of understory species on overstory trees have received less attention. We summarized the effects of understory species on soil physiological properties, soil fauna activities, leaf litter decomposition, and ecophysiology and growth of the overstory species. Then the effects of distur-bance on understory-overstory interactions were discussed. Finally, an ecophysiology-based concept model of understory effects on overstory trees was proposed. Understory removal experiments showed that the study area, overstory species age, soil fertility and understory species could significantly affect the understory-overstory interactions.

Research progress on the mechanisms and influence factors of nitrogen retention and transformation in riparian ecosystems

YANG Dan, FAN Da-yong, XIE Zong-qiang, ZHANG Ai-ying, XIONG Gao-ming, ZHAO Chang-ming, XU Wen-ting

2016, 27(3):  973-980.  doi:10.13287/j.1001-9332.201603.040

Asbtract ( 317 )   PDF (559KB) ( 314 )  

Riparian zone, the ecological transition buffer between terrestrial and aquatic ecosystems (rivers, lakes, reservoirs, wetlands, and other specific water bodies) with unique eco-hydrological and biogeochemical processes, is the last ecological barrier to prevent ammonium, nitrate and other non-point nitrogen pollutants from adjacent water bodies. Based on a summary of current progress of related studies, we found there were two major mechanisms underpinning the nitrogen retention/removal by the riparian ecosystems: 1) the relative locations of nitrogen in the soil-plant-atmosphere continuum system could be altered by riparian vegetation; 2) nitrogen could also be denitrified and then removed permanently by microorganisms in riparian soil. However, which process is more critical for the nitrogen removal remains elusive. Due to large variances of hydro-dynamic, vegetation, microbial, and soil substrate properties in nitrogen retention and transformation with various watersheds, it’s difficult to identify which factor is the most important one driving nitrogen cycle in the riparian ecosystems. It is also found that the limitation of study methods, paucity of data at large spatial and temporal scale, and no consensus on the riparian width, are the three major reasons leading to large variances of the results among studies. In conclusion, it is suggested that further efforts should be focused on: 1) the detailed analysis on the successive environmental factors with long-term; 2) the application of a comprehensive method combining mathematical models, geographic information system, remote sensing and quantified technique (such as the coupled technique of the isotopic tracer and gas exchange measurement); 3) the implementation of studies at large temporal and spatial scales. It is sure that, these efforts can help to optimize the nitrogen removal pathways in the riparian ecosystems and provide scientific basis for ecosystem management.

Oxidative stress-related signals and their regulation under Cd stress: A review

ZHANG Ran-ran, ZHANG Peng, DU Shao-ting

2016, 27(3):  981-992.  doi:10.13287/j.1001-9332.201603.002

Asbtract ( 450 )   PDF (752KB) ( 209 )  

Contamination of heavy metal in soil causes several severe environmental problems. Cadmium is one of the most toxic metals to organisms. In plants, Cd toxicity often results in over-accumulation of reactive oxygen species (ROS), which causes oxidative damage to the plant organs. In this review, we discussed the processes of how Cd stress causes over-accumulation of ROS in plant and how plant recovers from the Cd-induced oxdative stress. We especially focused on the roles of signal, including nitric oxide (NO), calcium (Ca), plant hormones (e.g. auxin and abscisic acid) and mitogen-activated protein kinases (MAPKs), in above two processes. Our review may provide theoretical basis for future research on the mechanism of plant tolerating Cd stress.

Research progresses on methanogenesis pathway and methanogens in coastal wetlands

WANG Jie, YUAN Jun-ji, LIU De-yan, XIANG Jian, DING Wei-xin, JIANG Xian-jun

2016, 27(3):  993-1001.  doi:10.13287/j.1001-9332.201603.014

Asbtract ( 485 )   PDF (562KB) ( 186 )  

Coastal wetlands contribute about 75% to the global oceanic CH₄ emissions, thus play a vital role in global C cycles. In this paper, we provided a perspective on researches on metabolic, phylogenetic, and ecological diversity of the methanogenic archaea and the regulating environmental factors in coastal wetlands. Because of the presence of more favorable electron acceptors such as sulfate, methanogenesis via CO₂ reduction and acetate fermentation are limited by availability of substrates, and hydrogenotrophic and acetotrophic methanogens generally express low relative abundance. In contrast, “non-competitive” substrates such as methanol and methylated compounds have been shown to contribute substantially to methane formation in coastal wetlands, and the facultative methanogens are predominant in those environments. Salinity regulates vegetation zonation and is related to SO₄^2- concentration, by regulating types of methanogenic substrates and contents of compe-titive electron acceptors, indirectly affects the structure and function of methanogens. Major uncertainties in the current studies include the following: methanogen community structure, the key environmental factors regulating methane pathway, and their effects on methane emissions in coastal wetlands.

Research progress on wind erosion control with polyacrylamide (PAM)

LI Yuan-yuan, WANG Zhan-li

2016, 27(3):  1002-1008.  doi:10.13287/j.1001-9332.201603.030

Asbtract ( 431 )   PDF (468KB) ( 156 )  

Soil wind erosion is one of the main reasons for soil degradation in the northwest region of China. Polyacrylamide (PAM), as an efficient soil amendment, has gained extensive attention in recent years since it is effective in improving the structure of surface soil due to its special physical and chemical properties. This paper introduced the physical and chemical properties of PAM, reviewed the effects of PAM on soil wind erosion amount and threshold wind velocity, as well as the effect differences of PAM in soil wind erosion control under conditions of various methods and doses. Its effect was proved by comparing with other materials in detail. Furthermore, we analyzed the mecha-nism of wind erosion control with PAM according to its influence on soil physical characteristics. Comprehensive analysis showed that, although some problems existed in wind erosion control with (PAM), PAM as a sand fixation agent, can not only enhance the capacity of the soil resis-tance to wind erosion, but also improve soil physical properties to form better soil conditions. Besides, we proposed that combination of PAM and plant growth would increase the survival rate of plants greatly, control soil wind erosion in wind-erosive areas, and improve the quality of the ecological environment construction. Thus, PAM has practically important significance and wide application prospect in controlling soil wind erosion.