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Pteroceltis tatarinowii Maxim.(Ulmaceae),a tertiary relict plant of a temperate deciduous tree species endemic to China,is widely distributed in bare limestone mountains across the mainland in China.The bark(phloem fiber) of this plant has long since been used as the sole raw material for manufacturing Chinese traditional Xuan Paper.However,the species are subject to many threats due to its distribution pattern characterized by small patches;its decreasing population size resulted from overexploitation,and reduction of the original forest ecosystem.Thus,it has now been listed as a rare and endangered plant(National Grand III) in China. Using inter-simple sequence repeat markers,the genetic diversity and structure of 628 individuals from 27 populations of P.tatarinowii were detected.A total of 66 bands,of which 63 were polymorphic,were presented from the 8 selected primers screening across all samples,with the percentage of polymorphic bands up to 95.45%.The result of POPGENE revealed quite high level genetic diversity for the plant at the species level(PPB=95.45%,Ao=1.9545,Ae=1.5729,He=0.3335,I=0.4980).At the population level,TS population from Gansu harbored the highest genetic diversity(PPB=84.85%,Ao=1.8485,Ae=1.5217,He=0.3033,I=0.4516),whereas NL population from Guangdong with the lowest genetic variation(PPB=54.55%,Ao=1.5455,Ae=1.3135,He=0.1841,I=0.2756).The mean population genetic level(PPB=69.98%,Ao=1.6998,Ae=1.4449,He=0.2561,I=0.3793) and population genetic differentiation of P.tatarinowii(Gst=0.23,ФST=0.25) were both at the middle level compared to other species.Gene flow(Nm) was estimated to be 1.65.In addition,different genetic variation and patterns were found between North China and South China.Populations of North China presented higher genetic diversity(PPB=95.45%,He=0.3332,I=0.4964) and lower genetic differentiation(ФST=0.22) than those of South China(PPB=93.94%,He=0.3220,I=0.4814 and ФST=0.25).It would seem the extant genetic pattern of P.tatarinowii was might mainly attributed to its long evolutionary history,wide-ranging distribution,outcross mating system,long life cycle and complex differences of terrain and vegetation between North China and South China. According to our aforementioned results and the evidence from our cpDNA data,in situ conservation was the preferred way to maintain the species′ high level genetic diversity.Especially,much more attention should be paid to populations with higher genetic diversity(TS,JX and QY) and populations harboring peculiar cpDNA haplotypes(XA,SD,ML,NXS,LP,YF,WYS,GL,AL).In the condition of establishment of artificial plantation and germplasm bank,the above peculiar populations should been given prior consideration.Regarding the genetic pattern difference between South China and North China,more populations in South China and fewer representative populations with more individuals in North China should been sampled to obtain the utmost genetic diversity of P.tatarinowii.

Pear jujube(Ziziphus jujuba Mill.) as a common tree crop in the Loess Plateau region ofChina,but its ecological and economic benefits have failed to be fully realized because of the shortage of water resources.Therefore,improving jujube yield and water use efficiency are key goals.Studies of the water deficit index and water consumption rules can help to design more optimal irrigation systems and improve water use efficiency.In 2010 and 2011,we studied the water consumption of 4-year-old jujube plants subjected to one of four soil water treatments during their flowering and fruit development periods.We analyzed the correlation of water consumption to variation in trunk diameter and established a regression model.Our goal was to determine how pear jujube stem diameter responded to water conditions during the flowering and fruit development periods to determine a suitable water deficit index to use in building irrigation systems.The flowering and fruit development periods of pear jujube are critical water demand periods.Because these two processes define the main period of reproductive growth,they determine the quantity,volume,weight,and yield of fruit.Stem diameter change indexes included daily mean trunk diameter(MTD),daily maximum trunk diameter(MXTD),maximum daily shrinkage in trunk diameter(MDS),and daily growth of stem diameter(DG).The results indicated that(1) the tree water use increased with an increase in soil water content.Regardless of the treatment differences in soil water conditions,the maximum daily water use all occurred during the week following irrigation,and water consumption during the fruit expansion stage was greater than in flowering and fruit set stages.(2) Two years of experimental data proved that the logistic function could precisely express the changes in MTD and MXTD in the critical water demand periods of jujube,so these two indexes were equivalent in terms of assessing jujube trunk diameter growth during the study period,even though the growth rate varied annually and among treatments.(3) Under the high-water treatment,the indices derived from the trunk diameter(MTD,MXTD,MDS,and DG) were not sensitive to water consumption,while in the low-water treatment,MDS had a highly significant correlation with daily water use compared with the other indexes,indicating its potential as an indicator of jujube water consumption under water deficit conditions.The regression model between water consumption and trunk diameter that we established can be used to analyze the sensitivity of stem diameter variation to water deficit and to detect the water consumption status of pear jujube trees.

Forest fires are considered an important disturbance factor for forest ecosystems.Forest fires are influenced by ecological factors.There are different relationships between diverse ecological factors and forest fires in disparate vegetation regions in China.The objectives of this study were two-fold: i) to assess relationships between ecological factors(NDVI and weather elements) and probability of occurrence of fires(i.e.fire risk),and,ii) to establish fire probability models in four contrasting vegetation regions across China. This study covers the monsoonal region where plenty of rainfall is received but significant seasonal variation within dry and wet seasons are characterised by air mass transitions between inland air and oceanic air.The study area was divided into four sub-regions according to their distinct biomes: i) north China plain with a dominant vegetation of deciduous broad-leaved trees;ii) north-east of China dominated by cool temperate coniferous forest;iii) southeast of China dominated by mixed evergreen broadleaf and deciduous broad-leaved forest,and iv) southwest of China dominated by tropical rain forest.Fire data were extracted from the Along Track Scanning Radiometer of the European Space Agency.Daily values of weather elements from 245 stations covering majority of the four climatic regions above were obtained from China Meteorological Administration.Normalized Difference Vegetation Index(NDVI) was applied as a measure of vegetation status.We linked vegetation with location,time,altitude,weather elements,,and fire characteristics during 1998—2007 in the four regions above using semi-parametric logistic(SPL) regression models.Non-linear relationships between different ecological factors and fire risk(i.e.probability of fire ignition and occurrence of large fire events) were assessed by semi-parametric logistic regression models. We analyzed characteristics of forest fire activity in the four contrasting vegetation regions across China.NDVI was found to be a significant indicator of probability of fire ignition in all the four forest regions except tropical rain forest.On the other hand,NDVI had a significant effect on probability of occurrence of large fire events in all the three forest regions except for evergreen broadleaf region.There was a significant correlation between probability of fire ignition and altitude.Location was found to have a highly significant effect on fire risk in all the four regions,except for the cool temperate coniferous forest.Mean monthly values of ecological factors had more effect on probability of fire ignition than monthly maximum values of those ecological factors.On the contrary,maximum monthly values of ecological factors had more effect on probability of large fire events than mean monthly values of the ecological factors.For each of the four regions of China,a different model of probability of fire ignition and occurrence of large fire events was established.Graphs of observed versus estimated probabilities of large fire events and fire danger maps were produced from the probability models to assess robustness of these models.The results of these final models with selected ecological factors as explanatory variables seem reasonable.The analysis presents some of the dynamics of ecosystem-fire interactions and their value for management systems.

This paper investigated the variation in 17 main morphological characteristics of 3 Amorpha fruticosa populations inhabiting three sites(Lhasa,Qushui and Maqu) of the Qinghai-Tibet Plateau.Our results showed that there were striking differences in some of the morphological characteristics within and among A.fruticosa populations when compared the average coefficients of variation in these morphological characteristics.The average coefficients of the variation of 17 main morphological characteristics across the three populations were 0.09—0.37,with the average coefficient of new branch length variation being largest.In addition,the average coefficient of population variation in the Lhasa site greater than that for the other two sites.Principal component analysis(PCA) indicated that the accumulated contribution of the first four principal components was 86.6%,but the contribution of the first principal component was 40.9%,suggesting that the first four principal components explained most of the variation in the morphological characteristics.New branch length,new branch diameter,old branch diameter,taproot diameter and total length of the second-order lateral root explained the majority of the variation in morphological characteristics of A.fruticosa populations.Correlation analysis also indicated that there were complicated relationships between main factors(soil organic carbon,total nitrogen and so on) in the rhizosphere and the above five morphological characteristics.New branch length,taproot diameter showed significant positive or negative correlations(P 0.05) with the contents of soil nutrients,and in particular the content of soil organic carbon,total nitrogen,total phosphorus were significantly and negatively correlated(P0.05) with the five morphological characteristics.In addition,our results showed some of the differences in the distribution frequency of the first-order and second-order lateral root lengths of A.fruticosa plants within and among populations.The distribution frequency of the first-order lateral root lengths(10—20 cm and 20—30 cm)was generally larger than that for the other first-order lateral root lengths in the three sites,and the distribution frequency of the second-order lateral root lengths(0—10 cm,10—20 cm,20—30 cm,30—40 cm,≥40 cm) showed a decline trend in the Lhasa and Maqu sites.Moreover,the distribution frequency of the first-order and second-order lateral root lengths(≥ 40 cm) in the Maqu population was significantly greater than that for the populations of the Lhasa and Qushui sites.This study reported in the first time the variation in the main morphological characteristics of A.fruticosa plants in the alpine regions,which may have important implications for the management of such alpine grasslands in China.

The Dongting Lake is the largest lake in the Middle and Lower Yangtze River and ranks the second largest freshwater lake in China.Seasonal fluctuation of water-level in the Dongting Lake forms stable wetland resources.A large area of shallow marshes and mudflats,which are exposed over water surface during the non-flood season in the winter,provide habitats for several migratory birds.In recent years,the effects of the hydrological processes on wetland ecological system have aroused worldwide attention.The complex nonlinear relationship between the Yangtze River and the Dongting Lake has led significant changes in hydrological processes in the Dongting Lake after the running of the Three Gorges Project. Data sets of surface area in the Dongting Lake were extracted using MODIS imagery from 2000 to 2010.During interpretation process,NDVI index and NIR band threshold were set to 1000,meaning that NDVI and NIR band values less than 1000 were water wetlands and values higher than 1000 were beach wetlands,including mudflat wetlands,grass wetlands and reed wetlands.Since the water-level of the Chenglingji was proportional to the surface area in the Dongting Lake,the observed water-level data sets were used to validate the rationality of the extracted surface area data sets.The results revealed that correlation coefficient of the extracted surface area and water-level was 0.8058.Mann-Kendall(MK) nonparametric test showed that the Zs statistics were-2.4986,-3.0867 and-2.5421 in the 0.05 level of significance for the whole year,from June to September(flood season) and from October to May in the next year(non-flood season) during 2000 to 2010,respectively.The trends indicated that runoff in the Dongting Lake was reduced dramatically during the last decade.The average surface water area decreased 15.21% and 32.05% during flood season and non-flood season in 2010 compared with that in 2000. In the paper,wetlands in the Dongting Lake were divided into water wetlands and beach wetlands.More attention was paid to the changes of beach wetlands area during non-flood season because of its importance for migratory bird.The data sets of area of water wetlands and beach wetlands indicated that the area of water wetlands decreased dramatically while beach wetlands increased correspondingly from 2000 to 2010.Compared with the data in February,October,and December in 2000,29.98%,26.76%,and 9.02% water wetlands were changed into beach wetlands in the corresponding month in 2010,respectively.According to the statistics of observed water-level of the Chenglingji that firstly and lastly reached 24m,25m,26m,27m and 28m,water-level fluctuation was investigated.The results showed that water-level fluctuation from 24 m to 26 m led to earlier exposure of beach wetlands and later flood of beach wetlands,which prolonged the exposure time of beach wetlands.The change of water wetlands and beach wetlands promoted the evolution of mudflat wetland to grass wetland in the East Dongting Lake at water-level of 24m to 26m.In conclusion,it is multi-factors,including reduction of runoff from Sankou(Songzi,Ouhe,Taiping) and Sishui(River Xiang,River Zi,River Yuan and River Li) and reduction of rainfall etc.,that contributed to the responses of wetlands area to hydrological process of the Dongting Lake.The impoundment of the Three Gorges Project in September to October would further aggravate the trend of water wetlands changing into beach wetlands.

Optimal time budget for behaviours may be constrained by intrinsic and extrinsic factors forcing animals to balance their daily energetic needs.From June to August in 2005 and 2010,the behavioural time budget and diurnal rhythm of the female Tibetan gazelles,Procapra picticaudata,were studied by focal animal sampling along the Qinghai-Tibet Highway(QTH) in the Kekexili National Nature Reserve.We restricted the sampling within 200 m from the QTH.In the end,a total of 255 observation units were collected.All behaviours were divided into five categories,Foraging,Vigilance,Lying,Moving and Other,and there was a significant difference among them using the Kruskal-Wallis H test(P0.001).Foraging and resting,accounting for(42.02±2.22)% and(31.21±2.71)% respectively,were the two main behaviours of the gazelles.This might relate to the low aboveground biomass,36.49—63.85 g/m2.The gazelles should spend more time foraging to obtain more nutrition.Moreover,as rumination indicates,more lying could assist in allowing the food to digest and thus nutrient assimilation.The groups of the Tibetan gazelles comprised from one to 12 individuals,but the groups with 11 animals were absent in this study.Analysis results of the Spearman rank correlations showed that with the increase of group size,the gazelles increased time foraging(P0.05) and decreased time vigilance(P0.001),which were due to the combination of the dilution hypothesis and the detection hypothesis.Theoretically,lactation carried a high energetic cost and the lambs were vulnerable to the predators,wolves and raptors.The gazelles with a lamb(mothers) were supposed to increase their time on foraging and vigilance comparing with the individuals without a lamb(female).However,results of the Mann-Whitney U tests suggested that there were no significant differences in foraging,vigilance and other between females and mothers,however the mothers devoted more time to moving(P0.01) and less time to lying(P0.05) than those of females without a lamb.Increasing moving could not only allow them to find new food resources easily but also avoid the predation risk in time,so the moving behaviour could play the role of vigilance to a certain extent.The peaks of foraging were recorded at 8:00—8:59,10:00—12:59 and 16:00—19:59,which were staggered with the foraging peaks of Tibetan antelopes inhabiting the same area.Temporal niche division could explain the coexistence of sympatric ungulates.The trend of lying was opposite to that of foraging owing to the trade-off among behaviours.Similar lying-foraging-lying transformation could be shown in many other ungulates.The only peak of vigilance occurred at 14:00—14:59,which could be explained by the variation of traffic flow on the QTH.The QTH plays an important role in Tibetan economic development and transports in 85% of imports and about 90% of exports from the Tibetan Autonomous Region.There was a significant trend of traffic flow and the peak,which occurred during 12:00—15:00.According to the risk-disturbance hypothesis,the Tibetan gazelles would express high vigilance level with the high human distance,i.e.the high traffic flow.The Kruskal-Wallis H tests indicated that the five behavioural categories showed significant variance among the periods of diurnal time(P0.05).