共查询到20条相似文献，搜索用时 203 毫秒
1.
Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities.Consequently,T.taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources(deep soil water and groundwater),reflecting its adaptations to the different habitats in the arid desert environment.These findings improve our understanding on determining the water sources and water use strategies of T.taklamakanensis in the Taklimakan Desert. 相似文献
2.
郁金香属百合科郁金香属多年生鳞茎草本植物,又称洋荷花、草麝香、牡丹百合等,是风靡世界的切花之一,用作花篮、花束和插瓶等装饰品制作,每年的销售量十分巨大,种植者经济效益高。随着产业结构的调整,江苏省许多地方形成郁金香鲜切花基地,但在生产过程中,我们发现每个环节都有可能受到真菌、细菌、病毒病的危害,从而影响到植株的正常生长,降低切花的品质和观赏性,严重时会造成毁灭性危害。因此,防治郁金香病害的发生及发展,是切花生产者首先要考虑的问题。现将郁金香生产中常见的病害发其防治方法介绍如下,以便与广大读者共飨。 相似文献
3.
The status of regional biodiversity is determined by habitat quality.The effective assessment of habitat quality can help balance the relationship between economic development and biodiversity conservation.Therefore,this study used the InVEST model to conduct a dynamic evaluation of the spatial and temporal changes in habitat quality of the Tarim River Basin in southern Xinjiang Uygur Autonomous Region of China by calc ulating the degradation degree levels for habitat types that were caused by threat factors from 1990 to 2018(represented by four periods of 1990,2000,2010 and 2018).Specifically,we used spatial autocorrelation analysis and Getis-Ord Gi*analysis to divide the study area into three heterogeneous units in terms of habitat quality:cold spot areas,hot spot areas and random areas.Hemeroby index,population density,gross domestic product(GDP),altitude and distance from water source(DWS)were then chosen as the main disturbance factors.Linear correlation and spatial regression models were subsequently used to analyze the influences of disturbance factors on habitat quality.The results demonstrated that the overall level of habitat quality in the TRB was poor,showing a continuous degradation state.The intensity of the negative correlation between habitat quality and Hemeroby index was proven to be strongest in cold spot areas,hot spot areas and random areas.The spatial lag model(SLM)was better suited to spatial regression analysis due to the spatial dependence of habitat quality and disturbance factors in heterogeneous units.By analyzing the model,Hemeroby index was found to have the greatest impact on habitat quality in the studied four periods(1990,2000,2010 and2018).The research results have potential guiding significance for the formulation of reasonable management policies in the TRB as well as other river basins in arid areas. 相似文献
4.
As an important natural resource,forest land plays a key role in the maintenance of ecological security.However,variations of forest land in the agropastoral ecotone of northern China(AENC)have attracted little attention.Taking the AENC as an example and based on remote-sensing images from 2000,2010 to 2020,we explored the spatiotemporal variation of forest land and its driving factors using the land-use transfer matrix,spatial autocorrelation analysis and spatial error model.The results showed that from 2000 to 2020,the total area of forest land in the AENC increased from 75,547.52 to 77,359.96 km2 and the changes were dominated by the transformations among forest land,grassland and cropland,which occurred mainly in areas with the elevation of 500-2000 m and slope of 15°-25°.There was obvious spatial agglomeration of forest land in the AENC from 2000 to 2020,with hot spots of forest land gathered in the southern marginal areas of the Yanshan Mountains and the low mountainous and hilly areas of the Loess Plateau.The sub-hot spots around hot spots moved southward,the sub-cold spots spread to the surrounding areas and the cold spots disappeared.The spatiotemporal variation of forest land resulted from the interactions of natural environment,socioeconomic and policy factors from 2000 to 2020.The variables of average annual precipitation,slope,terrain relief,ecological conversion program and afforestation policy for barren mountains affected the spatial pattern of forest land positively,while those of annual average temperature,slope and road network density influenced it negatively. 相似文献
5.
Taking Gansu province as a model case,this study provides an integrated analysis on the eco-economic system of arid and semi-arid region based on emergy synthesis theory. Through calculating the values of renewable emergy flow,non-renewable resources,imported emergy,exported emergy,waste emergy,and total emergy during the period of 1978-2007,the performance of Gansu eco-economic system was analyzed. The results indicated that the renewable emergy flow within the province basically remained steady state which was estimated at 2.99×1022 solar emjoules (sej) from 1978 to 2007. The imported emergy and exported emergy were estimated at 3.75×1017 sej and 2.99×1020 sej in 1978 and increased to 1.07×1022 sej and 1.44×1022 sej respectively in 2007. The nonrenewable emergy flow was estimated at 1.62×1022 sej and increased to 1.85×1023 sej,with annual growth rate of 8.7%,while the estimated total emergy was 4.58×1022 sej in 1978 and increased to 2.11×1023 sej in 2007,with annual growth rate of 5.41%. Our results indicate a deteriorate situation between economic development and environmental protection in the region. The rapid economic growth in the past thirty years was based on a great consumption of nonrenewable resource and caused continuous decrease in the capacity of sustainable development. The environmental loading ratio was 0.53 in 1978,increased to 6.06 in 2007,indicating a rapid degradation of the regional environment quality. We calculated that the actual population was 1.53 times the renewable resource population in 1978,increased to 7.06 times in 2007. During the period of 1978-2007,the emergy rose from 2.45×1015 sej/(capita·a) to 8.07×1015 sej/(capita·a). Our analysis revealed that the emergy density presented a trend of gradual increase,and then the emergy currency ratio in Gansu decreased from 7.08×1013 sej/Chinese Yuan to 7.82×1012 sej/Chinese Yuan. 相似文献
6.
Spatial heterogeneity for grain size distribution of eolian sand soil on longitudinal dunes in the southern Gurbantunggut Desert 总被引：3，自引：1，他引：2
The grain size composition, distribution characteristics and spatial variation of eolian sand soil on distinct positions across two longitudinal dunes and interdune areas were studied by means of conventional grain size analysis and geostatistical methods. In the study, 184 samples of eolian sand soil from the 0-30cm layer were systemically collected and measured from two longitudinal dunes and interdunes in the southern Gurbantunggut Desert. The results show that the dominant grain sizes are fine and very fine sands, and the differences of grain size compositions between the distinct geomorphologic positions are significant. The contents of clay and silt are highest on the interdune areas and lowest on the crests, and higher on the leeward slopes than on the windward slopes. The contents of very fine and fine sands are highest on the windward slopes and lowest on the crests. The contents of medium, coarse and very coarse sands are lowest on the interdune lands, and highest on the crests, and are identical on the two slopes. The coarser sizes (φ1) and mean sizes (Mz) for eolian sand soil all have a varying tendency from fine to coarse sizes with interdune area → leeward slope → windward slope → crest, and the sorting (σ) are poorly to well sorted. The results of geostatistical analysis reveal that φ1, Mz and σ values are moderately to strongly spatially autocorrelated. The values of the spatially correlated ranges are φ1<σ相似文献
7.
1 农业形势及农作物重大病虫害发生情况 2007年是实施"十一五"规划的第2年.中央一系列的政策继续向农业倾斜.农业部提出了发展现代农业的"十大行动"计划,各级植物保护技术推广部门,进一步加大了对农作物有害生物的防控力度,全力服务于发展现代农业"十大行动"计划的实施,各项工作进展顺利. 相似文献
8.
1 黄瓜病毒病
1）选栽抗病品种和耐病品种,减少发病。
2）培植壮苗,早育苗,铺盖地膜,早定植,底肥施足,增施磷钾肥,及时浇水,特别是苗期土壤不能干旱,结瓜后浇水带肥。彻底清除田间杂草及地边周围的杂草,发现病株立即拔除。 相似文献
9.
In this study,we analyzed the hydrological and meteorological data from the Syr Darya River Basin during the period of 1930–2015 to investigate variations in river runoff and the impacts of climate change and human activities on river runoff.The Syr Darya River,which is supplied by snow and glacier meltwater upstream,is an important freshwater source for Central Asia,as nearly half of the population is concentrated in this area.River runoff in this arid region is sensitive to climate change and human activities.Therefore,estimation of the climatic and hydrological changes and the quantification of the impacts of climate change and human activities on river runoff are of great concern and important for regional water resources management.The long-term trends of hydrological time series from the selected 11 hydrological stations in the Syr Darya River Basin were examined by non-parametric methods,including the Pettitt change point test and Mann-Kendall trend tests.It was found that 8 out of 11 hydrological stations showed significant downward trends in river runof f.Change of river runoff variations occurred in the year around 1960.Moreover,during the study period(1930–2015),annual mean temperature,annual precipitation,and annual potential evapotranspiration in the river basin increased substantially.We employed hydrological sensitivity method to evaluate the impacts of climate change and human activities on river runoff based on precipitation and potential evapotranspiration.It was estimated that human activities accounted for over 82.6%–98.7%of the reduction in river runoff,mainly owing to water withdrawal for irrigation purpose.The observed variations in river runoff can subsequently lead to adverse ecological consequences from an ecological and regional water resources management perspective. 相似文献
10.
水稻秧苗僵苗的症状表现是植株矮小,叶片细瘦,直立不披散,稻丛呈簇立状,根细而稀,新根少。根据秧苗初期因僵苗程度不同,长相长势有所区别,大致可分3个阶段：发僵,为黄化阶段,叶色较淡,矮小萎黄,锈根多,白根少,呈现出营养不良的症状;以后随着生理缺磷程度的加重,进入蓝化阶段，叶色暗绿发蓝，有的黄中带红，叶片沿纵脉呈环状卷曲，老根直伸向下，根毛稀少，这是由于生理缺磷影响能量代谢，使光合作用产物的运输受到严重阻碍导致的；僵苗严重时为红化阶段，老叶变红色，其余叶片除最新抽出叶呈全绿色外，均有不同程度的叶尖枯焦，远看苗色发红。 相似文献
11.
国内农业植物检疫（以下简称植物检疫）是以法律法规为依据、检疫技术为后盾、植物检疫行政许可和执法监督为保障来控制农业有害生物传播、蔓延、危害,达到促进农产品流通,保护农业生态,确保农业生产高产、优质、高效的目的。植物检疫行政许可在植物检疫工作中起着关键的作用。现把江山市2005年以来贯彻实施《行政许可法》和农业部有关农业行政许可规定过程中的有关情况概述如下。 相似文献
12.
13.
壳聚糖在农业上应用的研究进展 总被引：6，自引：0，他引：6
根据国内外最新的研究应用情况,筒述了壳聚糖在农业上作为种子处理剂、植物生长调节剂、植物病害诱抗剂、降解性地膜、肥料和土壤改良剂、果蔬保鲜剂等的应用情况及发展前景. 相似文献
14.
Understanding the spatiotemporal patterns of the forage-livestock balance is imperative for regionally arranging animal husbandry production while ensuring sustainable grassland-ecosystem service use.The Xilin Gol steppe is an important native grassland resource in Inner Mongolia Autonomous Region,China.This study aimed to elucidate the dynamics of the forage-livestock balance in the Xilin Gol steppe during the period 2000–2015.We evaluated the forage production and corresponding livestock carrying capacity(LCC)in the growing seasons of 2000–2015 using remote sensing data and field surveys.The spatiotemporal patterns of the forage-livestock balance were then assessed at regional,city(including city,county and banner),and village scales using statistical and household survey data.The results showed that both forage production and LCC decreased in the Xilin Gol steppe from east to west.During the period 2000–2015,the regional average forage production and corresponding LCC fluctuated without following a distinct trend,but were consistent with the variations in precipitation.The forage-livestock balance varied with time,space,and scale.At the regional scale,steppes were overgrazed in the early 2000s,but a forage-livestock balance or even grazing potential was achieved in other years.At the city scale,approximately half of the region exhibited a"forage-livestock balance"since 2000.However,about half of the region still experienced overgrazing,which mainly located in the southwest sandy zones.Such changes may have been affected by the variations in grassland quality,forage production,compensation payment,and so on.We suggest a location-specific management scheme for grazing constraints,ecological compensation payment,and industry development to aid in harmonizing animal husbandry and environmental restoration,while promoting sustainable development goals by 2030. 相似文献
15.
16.
Groundwater plays a dominant role in the eco-environmental protection of arid and semi-arid regions.Understanding the sources and mechanisms of groundwater recharge,the interactions between groundwater and surface water and the hydrogeochemical evolution and transport processes of groundwater in the Longdong Loess Basin,Northwest China,is of importance for water resources management in this ecologically sensitive area.In this study,71 groundwater samples(mainly distributed at the Dongzhi Tableland and along the Malian River)and 8 surface water samples from the Malian River were collected,and analysis of the aquifer system and hydrological conditions,together with hydrogeochemical and isotopic techniques were used to investigate groundwater sources,residence time and their associated recharge processes.Results show that the middle and lower reaches of the Malian River receive water mainly from groundwater discharge on both sides of valley,while the source of the Malian River mainly comes from local precipitation.Groundwater of the Dongzhi Tableland is of a HCO3-Ca-Na type with low salinity.The reverse hydrogeochemical simulation suggests that the dissolution of carbonate minerals and cation exchange between Ca2+,Mg2+and Na+are the main water-rock interactions in the groundwater system of the Dongzhi Tableland.Theδ18O(from-11.70‰to-8.52‰)andδ2H(from-86.15‰to-65.75‰)values of groundwater are lower than the annual weighted average value of precipitation but closer to summer-autumn precipitation and soil water in the unsaturated zone,suggesting that possible recharge comes from the summer-autumn monsoonal heavy precipitation in the recent past(≤220 a).The corrected 14C ages of groundwater range from 3,000 to 25,000 a old,indicating that groundwater was mainly from precipitation during the humid and cold Late Pleistocene and Holocene periods.Groundwater flows deeper from the groundwater table and from the center to the east,south and west of the Dongzhi Tableland with estimated migration rate of 1.29-1.43 m/a.The oldest groundwater in the Quaternary Loess Aquifer in the Dongzhi Tableland is approximately 32,000 a old with poor renewability.Based on theδ18O temperature indicator of groundwater,we speculate that temperature of the Last Glacial Maximum in the Longdong Loess Basin was 2.4℃-6.0℃ colder than the present.The results could provide us the valuable information on groundwater recharge and evolution under thick loess layer,which would be significative for the scientific water resources management in semi-arid regions. 相似文献
17.
18.
魔芋是我国西部山区调整农业产业结构和带动贫困山区农民脱贫攻坚的1个重要项目.但是,2008年1月10日至2月上旬.长江中、下游及其以南地区出现大范围持续低温雨雪冰冻天气. 相似文献
19.
ZHANG Pei DENG Mingjiang LONG Aihua DENG Xiaoya WANG Hao HAI Yang WANG Jie LIU Yundong 《干旱区科学》2020,12(1):73-89
In arid areas,ecological degradation aroused by over-exploitation of fresh water,expansion of artificial oasis and shrinkage of natural oasis,has drawn attention of many scholars and officials.The water and ecological footprints can be used to quantitatively evaluate the water consumption of social-economic activities and their influence on the eco-environments.In addition,increase of the water footprint indicates the expansion of artificial oasis,and the influence on the natural oasis could be reflected by the variation of the ecological footprint.This study was conducted to answer a scientific question that what is the quantitative relationship between the expansion of the artificial oasis and the degradation of the natural oasis in the arid environments of Xinjiang,China.Thus,based on the social-economic data,water consumption data and meteorological data during 2001–2015,we calculated the water and ecological footprints to express the human-related pressure exerted on the water resources and arid environments in Xinjiang(including 14 prefectures and cities),and explore the relationship between the water and ecological footprints and its mechanism by using the coupling analysis and Granger causality test.The results show that both the water and ecological footprints of Xinjiang increased significantly during 2001–2015,and the increasing rate of the ecological footprint was much faster than that of the water footprint.The coupling degree between the water and ecological footprints was relatively high at the temporal scale and varied at the spatial scale.Among the 14 prefectures and cities examined in Xinjiang,the greater social-economic development(such as in Karamay and Urumqi)was associated with the lower coupling degree between the two footprints.Increases in the water footprint will cause the ecological footprint to increase,such that a 1-unit increase in the consumption of water resources would lead to 2–3 units of ecological degradation.The quantitative relationship between the increases of the water and ecological footprints,together with the intensities of water consumption both in the natural and artificial oases of Tarim River Basin,have approved the fact that the formation and expansion of 1 unit of the artificial oasis would bring about the degradation of 2 units of the natural oasis.These conclusions not only provide a technical basis for sustainable development in Xinjiang,but also offer a theoretical guide and scientific information that could be used in similar arid areas around the world. 相似文献
20.
Water shortage is one bottleneck that limits economic and social developments in arid and semi-arid areas.As the impacts of climate change and human disturbance intensify across time,uncertainties in both water resource supplies and demands increase in arid and semi-arid areas.Taking a typical arid region in China,Xinjiang Uygur Autonomous Region,as an example,water yield depth(WYD)and water utilization depth(WUD)from 2002 to 2018 were simulated using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model and socioeconomic data.The supply-demand relationships of water resources were analyzed using the ecosystem service indices including water supply-demand difference(WSDD)and water supply rate(WSR).The internal factors in changes of WYD and WUD were explored using the controlled variable method.The results show that the supplydemand relationships of water resources in Xinjiang were in a slight deficit,but the deficit was alleviated due to increased precipitation and decreased WUD of irrigation.WYD generally experienced an increasing trend,and significant increase mainly occurred in the oasis areas surrounding both the Junggar Basin and Tarim Basin.WUD had a downward trend with a decline of 20.70%,especially in oasis areas.Water resources in most areas of Xinjiang were fully utilized and the utilization efficiency of water resources increased.The water yield module in the InVEST model was calibrated and validated using gauging station data in Xinjiang,and the result shows that the use of satellite-based water storage data helped to decrease the bias error of the InVEST model by 0.69×108m3.This study analyzed water resource supplies and demands from a perspective of ecosystem services,which expanded the scope of the application of ecosystem services and increased the research perspective of water resource evaluation.The results could provide guidance for water resource management such as spatial allocation and structural optimization of water resources in arid and semi-arid areas. 相似文献