Ambient TSP concentration and dustfall variation in Urumqi,China

Total suspended particulate(TSP, particle diameter≤100 μm) was the dominant air pollutant and significantly influenced local air quality. In this paper, we investigated the interannual and seasonal variations of TSP and dustfall of the atmosphere over Urumqi, the capital city of Xinjiang Uygur autonomous region, northwestern China, basing on environmental monitoring records and meteorological data from 1986–2012. The results showed that during the study period, annual average TSP concentration decreased from 716 to 260 μg/m3, with an average level of 422.9 μg/m3, while dustfall intensity reduced from 350.4 to 166.6 t/(km2?a), with an average level of 259 t/(km2?a). Over 50% of the annual pollution days were induced mainly by TSP. Spring and winter had relatively higher dustfall intensities, and dense traffic and residential areas had the highest dustfall intensities in the Urumqi metropolitan area. With an annual average precipitation of less than 300 mm, atmospheric particulates in Urumqi could be hardly removed through wet deposition. During spring and summertime prevailing winds from northwest and northeast could carry aeolian dust particles from sandy deserts to Urumqi. Aeolian dusts from deserts would remain to be a priority regarding air pollution control in arid oasis cities.     

Spatial pattern of soil organic carbon in desert grasslands of the diluvial-alluvial plains of northern Qilian Mountains

The soil properties in arid ecosystems are important determinants of vegetation distribution patterns.Soil organic carbon(SOC)content,which is closely related to soil types and the holding capacities of soil water and nutrients,exhibits complex variability in arid desert grasslands;thus,it is essentially an impact factor for the distribution pattern of desert grasslands.In the present study,an investigation was conducted to estimate the spatial pattern of SOC content in desert grasslands and the association with environmental factors in the diluvial-alluvial plains of northern Qilian Mountains.The results showed that the mean values of SOC ranged from 2.76 to 5.80 g/kg in the soil profiles,and decreased with soil depths.The coefficients of variation(CV)of the SOC were high(ranging from 48.83%to 94.67%),which indicated a strong spatial variability.SOC in the desert grasslands of the study region presented a regular spatial distribution,which increased gradually from the northwest to the southeast.The SOC distribution had a pattern linked to elevation,which may be related to the gradient of climate conditions.Soil type and plant community significantly affected the SOC.The SOC had a significant positive relationship with soil moisture(P<0.05);whereas,it had a more significant negative relationship with the soil bulk density(BD)(P<0.01).However,a number of the variations in the SOC could be explained not by the environmental factors involved in this analysis,but rather other factors(such as grazing activity and landscape).The results provide important references for soil carbon storage estimation in this study region.In addition,the SOC association with environmental variables also provides a basis for a sustainable use of the limited grassland resources in the diluvial-alluvial plains of northern Qilian Mountains.     

山地荒漠草地封育对土壤质量的影响

[目的]评价封育草地土壤的质量.[方法]以北疆山地荒漠草地放牧和围封7年草地土壤为研究对象,分析土壤总有机碳、活性有机碳及碳库管理指数的变化.[结果]随着土层深度的增加土壤有机碳、土壤易氧化碳、土壤微生物量碳含量均呈降低趋势.与放牧相比,围封7年土壤易氧化碳与土壤有机碳含量升高,但差异不显著;土壤微生物量碳含量在5～ 50 cm各土层显著升高(P＜0.05).0～20 cm、35～ 50 cm土层碳库管理指数＞ 100.表明草地封育使土壤有机碳活度增大,同时增加了土壤碳的截存,土壤质量有所提升.[结论]围封后,土壤易氧化碳与土壤有机碳含量升高;土壤微生物碳含量显著升高;土壤表层与下层碳库管理指数高于放牧;荒漠漠地长期封育改善了土壤有机质状况和土壤碳库质理,增强了土壤碳汇功能.     

干旱荒漠区封育沙地植被群落特征变化研究

以天然植被围栏封育和人工种植+围栏封育措施下沙地植物群落为对象,以无封护的流动沙地做对照,研究了不同恢复措施对沙地群落物种组成及结构变化的影响.结果表明,(1)封育15 a后,人工种植+围栏封育区侵入物种的丰富度随演替的进展已达12种,其中猪毛菜7.562株/m~2,碟果虫实3.233株/m~2,雾冰藜3.017株/m~2,沙米1.615株/m~2,狗尾草1.112株/m~2.种类组成及生活型结构在向天然植被围栏封育区植物群落靠近,但两者间仍表现出较大差异.(2)在类型组成上,两种封育措施区差异主要表现在优势科及各科种类数量上.(3)在综合多样性特征上,两种措施区草被层的Shannon指数和丰富度指数存在显著差异,而其余各指数两者差异均不显著,但天然植被围栏封育区灌木层的生态优势度指数较高.(4)群落的相似性指数表明,两种封育措施间的植物群落差距较大,且2种封育措施下的植物群落与植被呈零星状分布的无封护措施的流动沙地相比,生态差距均十分显著,这表明封育可明显促进沙地植被的多样性恢复,其中人工种植对沙地植物群落物种多样性恢复的作用是相对缓慢而渐进的.     

Biogeography and conservation of taxa from remote regions: An application of ecological-niche based models and GIS to North-African canids

In North Africa, and especially in the Sahara Desert, biodiversity is poorly known. Of the five widespread canid species present, one is Data Deficient, three are considered widespread although habitat selection could limit their area of occupancy, and distribution maps available are coarse for conservation planning. This study identifies biogeographic patterns in North-African canids through the combination of high resolution presence data with 16 environmental factors. Predictive models trained in north-west Africa are projected to all North Africa. canids exhibited distinct biogeographical affinities. GIS tools and Maximum Entropy models identify a mixture of climatic and habitat factors as main predictors of species occurrence. Suitable habitats for North-African canids are mostly fragmented: probable occurrence was identified for Canis aureus in Saharan peripheral regions and mountains, for Vulpes pallida in a narrow band along the Sahel and in southern Saharan mountains, for Vulpes rueppellii throughout the Sahara, for Vulpes vulpes in northern Africa until the Sahara northern limit, and for Vulpes zerda in almost all Sahara. Areas of potential sympatry between species with similar niches and parapatric ranges are identified along relatively narrow bands. The small pixel size of projections allows the identification of suitable refuges for species otherwise absent in the driest Saharan habitats, providing framework data for the definition of the global conservation status of V. pallida, and conservation strategies for the guild. The biological value of Saharan mountains is emphasised as they constitute isolated suitable areas. Ecological-niche based models should be developed for other endangered Saharan vertebrates.     

新疆荒漠一年生植物区系组成、分布及资源类型

荒漠一年生植物生长速度快、繁殖力强,具有重要的饲用、药用和生态价值.通过文献资料与标本采集信息的考证和野外调查,明确了新疆荒漠一年生植物的物种数量、分布特征及资源类型.结果 表明:新疆荒漠一年生植物共有236种,隶属于20科109属,其中藜科为优势科,猪毛菜属为优势属.科可划分为4个分布区类型,以世界广布科为主,占总科...     

平山湖温性荒漠草地草畜平衡现状及发展措施

2008年通过对张掖市平山湖蒙古族乡草地、农牧业生产经营情况的入户调查,全乡有天然草地8.67万hm^2,可利用草地6.38万hm^2。草地理论载畜量为2.03万羊单位,实际存栏6.843万羊单位,超载4.813万羊单位,达237%。由于草地严重超载过牧,造成温性荒漠草地退化加剧,裸露草地数量增加,水土流失严重,草原生态环境日益恶化,使当地农牧民生产、生活受到严重的影响。必须通过调整优化畜群结构,使饲养牲畜公母比例由1∶1.4提高到1∶2.5-3.0,改变传统的全放牧饲养方式,加快畜群周转,达到草畜平衡,实现草地畜牧业可持续发展。     

乌兰布和沙漠东北部沙区人工林土壤钾素特征研究

通过对乌兰布和沙漠东北部沙区不同林地土壤样品的测定与分析,研究了林地土壤各形态钾素含量、相关性和垂直分异特征。结果显示:表层各形态钾素在各林地内呈不均衡分布。造林对表层土壤钾素具有不同程度的积累效应,特别是二白杨、小美旱以及固氮树种花棒、沙棘和沙枣;林地全钾含量中,各形态钾素所占比例不同,但平均97%以上的钾素植物难以直接利用;缓效钾是有效钾素非常重要的潜在给源。各林地有效性钾、速效钾和缓效钾含量绝大部分表层(0-20cm)高于下层(20-40cm),矿物钾和全钾主要决定于土壤母质,层次间差异很小。在干旱条件下,林地土壤含水量较高的树种以及固氮树种更有利于有效钾素的提升。各形态钾素间存在着不同程度的转化关系;有机质、CEC明显影响着各形态钾素的含量、转化及其有效性。整体而言,乔木提升有效性钾、速效钾和缓效钾含量稍优于灌木,但差异很小。因此,在沙区干旱条件下,建议推广对土壤质量提高和生态环境改善更具潜力的固氮沙生灌木。     

长期施肥下灰漠土有机碳组分含量及其演变特征

采用湿筛和重液悬浮的物理分组方法分析了18年不同施肥模式下灰漠土有机碳组分含量差异及其演变特征。结果表明:与不施肥相比,长期有机无机肥配施(NPKM和1.5 NPKM)增加各有机碳组分的效果最显著,且粗和细自由颗粒有机碳、物理保护有机碳、矿物结合有机碳增加速率最高,平均分别达到0.12、0.06、0.08及0.17g/(kg.a);秸秆还田使粗和细自由颗粒有机碳分别以0.05和0.03 g/(kg.a)的速率增加,而撂荒和施化肥维持着各有机碳组分的含量。不同有机碳组分间存在显著的相关性,其中以粗自由颗粒有机碳含量增幅最高,不同施肥模式下平均增幅是其它有机碳组分的2.18~.0倍;以矿物结合有机碳所占比例最高,达到56.9%7~7.8%,说明粗自由颗粒有机碳对施肥较敏感,而矿物结合有机碳是灰漠土固存有机碳的主要形式。综上分析,长期有机无机肥配施是提高灰漠土有机碳组分含量和培肥土壤的有效模式。     

畜禽粪便生态肥对灌漠土肥力质量及人参果品质和效益的影响

在温室内进行了畜禽粪便生态肥对灌漠土肥力质量及人参果品质和效益影响的研究.结果表明:畜禽粪便生态肥适宜施肥量比例为畜禽有机肥45.00 t?hm-2、人参果专用肥1.50 t?hm-2、聚丙烯酰胺0.09 t?hm-2;施用畜禽粪便生态肥与传统化肥比较,土壤容重和pH值降低5.39％和9.11％,总孔隙度、团聚体、CE...