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Artemisinin,being extracted from Artemisia annua L.,is recommended by the World Health Organization(WHO) as a drug for the initial treatment of malaria.During the growth and development of Artemisia annua L.in field cultivation,a large amount of this anti-malarial compound could be released into soil ecosystems by rain leaching,root exudation and plant residues,inhibiting the growth of plants around Artemisia annua L.and microbial reproduction in soils.Ectomycorrhizal fungi(ECMF) can increase the growth,nutrient uptake and stress resistance of woody plants following the formation of symbiotic associations,which is important for the sustainability of forest ecosystems.The allelopathic effects of this anti-malarial compound have been seldom reported on ECMFs and plants.In the present experiment,two ECMF strains,Suillus luteus 8(Sl 8) and Lactarius delicious 3(Ld 3),were isolated in the pine forest in Chongqing,China.They were grown in Pachlewski liquid medium to study the effects of different concentrations of artemisinin(0,20,40,80 mg/L) on fungal growth,efflux of H+ and organic acids,and uptake of nitrogen,phosphorus and potassium in vitro.Our results showed that the growth of the two ectomycorrhizal species was significantly inhibited by artemisinin.After being cultured for 14 days in the dark,fungal biomass was decreased by 89.13%(Sl 8)and 26.89%(Ld 3),respectively compared to the control(without artemisinin),indicating the higher sensitivity of Sl 8 than Ld 3 in response to artemisinin.Oxalic acid,succinic acid,malic acid,and citric acid were detected in the culture mediums with Ld 3 inoculated,while only two organic acids,oxalic acid and citric acid,were found with Sl 8.As artemisinin concentrations increased,the efflux of both H+ and organic acids from Ld 3 were increased in contrast to Sl 8 which had a low accumulation of H+ and oxalic acid but high citric acid in the culture medium.In addition,uptake and concentration of N,P and K in the fungal hyphae were significantly reduced following the addition of artemisinin.The capability of nutrient absorption by Sl 8 was almost lost under 80 mg artemisinin/L.Overall,our results showed that the two ECMFs varied significantly in H+ efflux,organic acid accumulation,growth suppression and nutrient uptake inhibition under artemisinin treatment.The results further suggest that artemisinin could alter the growth and nutrient uptake of ECMFs in forest soils,which could potentially risk changes in the distribution,performance and biodiversity of ECMFs in forest ecosystems.Artemisinin decomposes slowly,potentially leading to large amounts of the compound remaining in soils following the cultivation of Artemisia annua L.on a commercial scale.Artemisinin in those soils,particularly in Three Gorges areas in China where a large amount of Artemisia annua L.are grown,could influence not only the biodiversity of ECMF species directly in forest ecosystems but also the growth and health of forests indirectly.Improved understanding of the allelopathic effects of artemisinin on ECMFs could maintain the fungal biodiversity and function in sustainable forests,which is important for the health of natural forests.

The urban thermal environment is an important element for the urban ecological environment,urban climate and urban disasters.This paper selected MOD11A2,the MODIS LST night data to study the thermal environment evolution in Beijing,Shanghai and Guangzhou,which are the three major cities of China in the past decade.Three methods have been applied in the paper,Landscape centroid evolution,Landscape pattern index and spatial autocorrelation.Three main conclusions have been drawn as follows.Firstly the thermal landscape distributions in the three cities have moved from the suburb to the downtown.And the evolution trend of the thermal landscape is changed from the low temperature region,sub-middle temperature region to middle temperature region,sub-high temperature region and high temperature region.Secondly,among these five types of thermal landscape,the middle temperature region is the most prevalent.The urban thermal landscape fragmentation was highest in Shanghai among the three cities,and sub-middle and high temperature region has the highest fragmentation.The urban thermal landscape dispersion was highest in Beijing,and the dispersion of low and high temperature region was higher than the other types of thermal landscapes.Thirdly,thermal environment spatial autocorrelation analysis showed that the high-high temperature zones were adjacent,low-low temperature areas were adjacent,which are the main types in the temperature spatial agglomeration.And for Beijing and Guangzhou city,the high-high temperature zone located in the south of the city,the low-low temperature region located in the north.While,the spatial autocorrelation distribution of LST in Shanghai is more complicated.The distribution areas of high-high temperature varied among the three cities in the past decade.In Beijing,the distribution area increased shortly after decreasing,and in Guangzhou,the distribution area continued to decline,which preliminary reflects the heat island effect problem aggravated in Beijing,while weakened in Shanghai and Guangzhou. Through comparisons and analysis,the paper has provided a reference for urban planning and urban living environment improvements,but there are still some inadequacies to be further studied.Firstly,this study only selected the January night LST data in the three cities.Because the time factors,such as season,daytime and nocturne,will affect the urban heat environment pattern,the comprehensiveness of the thermal environment pattern changes need to be improved.In addition,the paper only selected the data in the period of three years,the evolution regulation of the urban thermal environment pattern is not precise.Secondly,the landscape of urban heat environment were impacted by many factors,including the pattern of landuse,urban surface construction,weather conditions,terrain,anthropogenic heat emissions factors and so on.The analysis between the urban heat environment and impact factors will help reveal the mechanism of urban heat environment and which will be studied further.

The treeline,which is defined as the upper limit of altitudinal tree distribution,is one of the most conspicuous vegetation boundaries worldwide.Treeline environments are generally characterized by harsh climatic conditions,which restrict tree growth and metabolic functions.Tree growth at the treeline is very sensitive to environmental changes,and it may be immediately influenced by small changes to limiting factors.Therefore,tree growth at the treeline can be used as an amplifier of external environmental changes,which has important implications for global climate change research.Fine resolution studies of tree radial variation on short temporal scales can be useful for exploring the interplay of the main physical variables that trigger the radial variation.From 19 Oct.2008 to 17 Oct.2009,we continuously monitored the stem radial variation of Larix principis-rupprechtii trees using point dendrometers,at the treeline of the Luya Mountains,in Shanxi,northern China.Our results showed that there were two reverse daily variation patterns in the warm and cold seasons,which were related to the daily transpiration rates and daily stem freeze-thaw cycles,respectively.In the warm seasons,the diurnal stem variation pattern was resolved into three phases:(1) radius contraction,(2) radius expansion,and(3) radius increment.Generally,during daytime,when tree transpiration exceeded water absorption,stem diameters usually decreased,and stem expansion occurred at night because of greater water absorption by the roots compared with water loss due to transpiration.In our study,a wide range of stem radius variations occurred during the stem freeze-thaw cycles during the cold seasons when the air temperature fluctuated around-5℃.The course of the cumulative radial variation during the year showed similarities among individuals representing the characteristic seasonal patterns.The average net stem radial increment of Larix principis-rupprechtii during the growing season was(2014.1±240.5) μm.Annual stem radial variation of Larix principis-rupprechtii was divided into four distinct periods:(1) spring stem rehydration,(2) summer stem rapid growth,(3) autumn stem dehydration contraction,and(4) winter stem stagnation.During different growth periods,the major environmental factors controlling stem radial variation were different.During the first period,the large radial increments were due to stem tissue rehydration by root pressure in early spring,and soil water content became the crucial environmental factor influencing stem radius variation.During the period of rapid stem growth in the summer,soil temperature was the major determining factor.Low soil temperature can inhibit net photosynthesis of Larix principis-rupprechtii,distribution of non-structural carbohydrates in the stem,and root activity and water uptake.The third period was characterized by the cessation of increments accompanied by dehydration of stem cells.These changes accompanied the declines in temperature and soil water content.Changes occurring in the cambia likely allow for over-wintering,which may be a survival strategy to avoid frost damage during cold winter conditions.During the fourth period,Larix principis-rupprechtii entered the dormancy stage and the stem remained relatively stable.It was observed that fluctuations in the radius of Larix principis-rupprechtii were mainly related to the changes in air temperature.

The distribution,colonization rate and diversity of arbuscular mycorrhizal(AM) fungi in the rhizosphere of seven medicinal plants species in Xiamen,Fujian province were studied.The spores of AM fungi were isolated by modified method of wet sieving and decanting technique and identifled based on spore morphology and subcellular characters.The results showed a strong symbiotic relationship between seven medicinal plants and AM fungi.The highest spore density(29.0 cfu per g soil) was found in Rhus chinensis while the lowest(4.7 cfu per g soil) was in Michelia figo.Spores of Gigaspora occurred rarely and only in Houttuynia cordata Thunb.,and Scutellospora only in Rosa laevigata Michx.Glomus melanosporum was most frequently associated with the 7 medicinal plants species.The highest mycorrhizal colonization(100%) was recorded in Camptotheca acuminata Decne while the lowest(4.5%) was in Houttuynia cordata Thunb.The results indicated that sixty three species of four genera of AM fungi were isolated,of which thirty-nine belonged to Glomus,eighteen to Acaulospora,two to Scutellospora and four to Gigaspora.Meanwhile,Glomus and Acaulospora were the dominant genera of the seven medicinal plants and G.melanosporum,A.excavata,G.ambisporum,G.clarum,and G.geosporum were the prevalent AM fungi.The highest species richness(26),Shannon-Wiener index(H)(2.29),and evenness(0.83) were found in Rhus chinensis,Rosa laevigata Michx.,and Mirabilis jalapa Linn.,in contrast to the lowest one in Houttuynia cordata Thunb.(9),Houttuynia cordata Thunb.(1.06) and Rhus chinensis.(0.39).The frequency(F) and importance value(I) of Glomus and Acaulospora in all the plants were higher than 50 percent.As the soil characteristic may play an important role in the ecological distribution of AM fungi,available P,available K,available N,organic matter,pH and electrical conductivity of the soil samples were investigated.In the present study,the colonization had no significant correlation with the soil factors.Spore density had a highly significantly negative correlation with pH values(P0.01).Species richness correlated significantly negatively with pH(P0.05),and had a highly significantly negative correlation with electrical conductivity,while highly positive correlation with spore density(P0.01).Shannon-Wiener index(H) had a highly significantly negative correlation with organic matter(P0.01).Evenness had a highly significantly negative correlations with soil organic matter and spore density(P0.01).These results indicated a high diversity of AM fungi in Xiamen.The effects of soil factors on colonization rate,spore density,species richness,Shannon-Wiener index(H) and evenness all varied with host plants.The colonization rate,spore density and species richness had negative correlations with pH values,available P,available N and electrical conductivity.The colonization rate and Shannon-Wiener index(H) had positive correlation with available K and evenness had positive correlation with available K,organic matter,pH and electrical conductivity.AM fungi may be a potent biological resource which can stimulate the growth of medicinal plants.This study provids a valuable germplasm and theoretical basis for AM fungal biotechnology to apply to medicinal standardization on planting.

Red fox,a canine predator inhabiting in the grassland of eastern Inner Mongolia,is positioned near the top of the food chain.It plays an important role in rodent control.Consequently,research on red fox helps scientists accumulate basic data and offers a scientific basis for the protection of grassland ecosystems and red fox management.Red fox habitat selection in the Dalai Lake Natural Reserve was systemically studied from November 2009 to January 2010 and from March to April 2010.Line transects were used for 101 plots known to be used by the red fox and for 144 comparison plots.We processed our field data and analyzed them using principal component analysis.Using landform analysis of the study area and other relevant research work,we defined seven significant factors influencing habitat: vegetation type,sheltering class,food abundance,snow depth,distance to water sources,distance to fences,and distance to residential areas.Our results show food and sheltering class were two key factors that affected red fox habitat selection.Distance to residential areas and distance to fences also affected the red fox habitat selection to some degree.Snow depth and distance to water sources had minimal effects on red fox habitat selection.Using Bayesian methods and 3S technology,we analyzed landscape features and studied red fox habitat distribution using an existing fox distribution map.We found that the red fox prefers two kinds of habitats: reed pond and willow shrub.Reed pond and willow shrub covered 1093.47 km2 of the analysis area;red foxes also occasionally use watercourses,typical grassland,and meadow steppe which covered 4721.79 km2;unsuitable habitat,including open water covered 1968.09 km2.Those were 14.05%,60.67%,and 25.29% of the analysis area,respectively.The unsuitable patches were mainly water covered with little sand;they were not studied.We concluded most of the suitable habitat patches for red fox are relatively smaller in size and fewer in number compared with red fox habitat in other areas previously studied by other researchers.The shapes of the three types of habitat listed above are suitable for the survival of the red fox,but the distribution of each type of patch is too concentrated to provide adequate distribution of the red fox population.We conclude the number of suitable patches should be increased to provide additional and more diverse types of grassland patches suitable for red fox across the landscape.We recommend controlling grazing to increase the density and the height of grass which,in turn,improves available sheltering habitat in patches suitable for red fox.Meadow used for grazing and meadow reserved for red fox habitat must be strictly separated.Through this method some relatively suitable patches could be improved to highly suitable patches for red fox.This would increase the red fox population and provide improved rodent control.

Soil water retention parameters are critical to quantify flow and solute transport in vadose zone, while the presence of rock fragments remarkably increases their variability. Therefore a novel method for determining water retention parameters of soil-gravel mixtures is required. The procedure to generate such a model is based firstly on the determination of the quantitative relationship between the content of rock fragments and the effective saturation of soil-gravel mixtures, and then on the integration of this relationship with former analytical equations of water retention curves (WRCs). In order to find such relationships, laboratory experiments were conducted to determine WRCs of soil-gravel mixtures obtained with a clay loam soil mixed with shale clasts or pebbles in three size groups with various gravel contents. Data showed that the effective saturation of the soil-gravel mixtures with the same kind of gravels within one size group had a linear relation with gravel contents, and had a power relation with the bulk density of samples at any pressure head. Revised formulas for water retention properties of the soil-gravel mixtures are proposed to establish the water retention curved surface models of the power-linear functions and power functions. The analysis of the parameters obtained by regression and validation of the empirical models showed that they were acceptable by using either the measured data of separate gravel size group or those of all the three gravel size groups having a large size range. Furthermore, the regression parameters of the curved surfaces for the soil-gravel mixtures with a large range of gravel content could be determined from the water retention data of the soil-gravel mixtures with two representative gravel contents or bulk densities. Such revised water retention models are potentially applicable in regional or large scale field investigations of significantly heterogeneous media, where various gravel sizes and different gravel contents are present.