Spatiotemporal variation of soil organic carbon in the cultivated soil layer of dry land in the South-Western Yunnan Plateau, China

The dynamics of soil organic carbon(SOC)in cropland is one of the central issues related to both soil fertility and environmental safety. However, little information is available at county level regarding the spatiotemporal variability of SOC in the southwestern mountainous region of China. Thus, this study aimed to explore spatiotemporal changes of SOC in the cultivated soil layer of dry land in Mojiang County,Yunnan Province, China. Data were obtained from the second national soil survey(SNSS) of 1985 and soil tests for fertilizer application carried out by the Mojiang Agricultural Bureau in 2006. The ANOVA test was applied to determine any significant differences between the datasets, while semivariogram analysis was performed on geostatistics via an ordinary Kriging method in order to map spatial patterns of soil organic carbon density(SOCD). The results revealed that SOCD in the cultivated soil layer significantly decreased from 3.93 kg m^(-2) in 1985 to 2.89 kg m^(-2) in 2006, with a total soil organic carbon stock(SOCS) decrease of 41.54×10~4 t over the same period. SOCS levels fell most markedly in yellow-brown soil at a rate of51.52%, while an increase of 8.70% was found in the analysed latosol. Geostatistical analysis also showed that the recorded changes in SOCD between 1985 and2006 were spatially structured. The decreasing trend might be attributed to the combined action of intense cultivation, major crop residue removal without any protective tillage measures, unreasonable fertilization and natural climatic diversity inducing a large decrease in SOC in the studied cultivated dry land region of Mojiang County. Therefore, management measures such as protective tillage should be undertaken in order to enhance soil C sequestration.

Characteristics of soil organic carbon andtotal nitrogen storages for differentland-use types in Central Yunnan Plateau

Two-factor analysis of variance and redundancy analysis were used to analyze the characte-ristics of soil organic carbon total nitrogen storage in garden land,forestland,grassland,farmland,and bare land in the Dachunhe watershed of Jinning District,Kunming City,Yunnan Province,China.The effects of the soil organic carbon,total nitrogen stratification ratio,soil physical and chemical factors on the storage characteristics of organic carbon and total nitrogen of different land-use types were analyzed.The results show that the rates of carbon and nitrogen stratification in soil from 0-20 cm and 40-60 cm of the same land-use types differed are statistically significant(P<0.05).The organic carbon and total nitrogen stratification ratio SR1 of garden land soil are 38.5%and 25.3%,respectively,which are higher than SR^(2).The soil organic carbon and total nitrogen stratification ratio SR^(2) of different land-use types are greater than SR1.There are statistically significant differences in the SR^(2) soil organic carbon and total nitrogen stratification ratios(P<0.05).Soil organic carbon and total nitrogen storage of diffe-rent land-use types gradually decrease with increasing soil depth,with the maximum soil organic carbon and total nitrogen storage in the 0-20 cm soil layer.Soil organic carbon and total nitrogen sto-rage at the same soil depth are significantly different(P<0.05).Soil organic carbon and total nitrogen storage in the garden land are greater than those in the other land-use types.Soil organic carbon and total nitrogen storage in 0-20 cm garden land are 4.96 and 3.19 times than those in bare land,respectively;soil organic carbon and total nitrogen storage are explained by 93.66%and 1.53%in redundancy analysis RDA1 and RDA2,respectively.All physicochemical factors except Available Phosphorus and pH are statistically significance with carbon and nitrogen storage(P<0.05).Soil cationic exchange capacity,Available Phosphorus,C/N ratio,and Moisture Content are positively correlated with organic carbon and total nitrogen storage.In contrast,soil Bulk Density is negatively correlated with organic carbon storage and total nitrogen storage.Available Phosphorus,C/N ratio,and Moisture Content are the main factors promoting soil organic carbon and total nitrogen accumulation.

Litter Decomposition of Emergent Plants along an Elevation Gradient in Wetlands of Yunnan Plateau,China

The decomposition of plant litter is a key process in the flows of energy and nutrients in ecosystems. However, the response of litter decomposition to global climate warming in plateau wetlands remains largely unknown. In this study, we conducted a one-year litter decomposition experiment along an elevation gradient from 1891 m to 3260 m on the Yunnan Plateau of Southwest China, using different litter types to determine the influences of climate change, litter quality and microenvironment on the decomposition rate. The results showed that the average decomposition rate(K) increased from 0.608 to 1.152, and the temperature sensitivity of litter mass losses was approximately 4.98%/℃ along the declining elevation gradient. Based on a correlation analysis, N concentrations and C︰N ratios in the litter were the best predictors of the decomposition rate, with significantly positive and negative correlations, respectively. Additionally, the cumulative effects of decomposition were clearly observed in the mixtures of Scirpus tabernaemontani and Zizania caduciflora. Moreover, the litter decomposition rate in the water was higher than that in the sediment, especially in high-elevation areas where the microenvironment was significantly affected by temperature. These results suggest that future climate warming will have significant impacts on plateau wetlands, which have important functions in biogeochemical cycling in cold highland ecosystems.

On Accelerating Development of Yunnan Plateau Characteristic Agriculture

Yunnan plateau characteristic agriculture is an essential force for increasing farmers' income and promoting prosperity of rural economy. The fundamental position of agriculture should be kept all the time. This paper analyzed practical basis and existing problems in development of Yunnan plateau characteristic agriculture. In line with these problems,it present ideas,main points and objectives of Yunnan plateau characteristic agriculture,and finally came up with recommendations for accelerating development of Yunnan plateau characteristic agriculture.

Trends in sunshine duration and atmospheric visibility in the Yunnan-Guizhou Plateau,1961-2005

Using the observed data from 184 stations over the Yunnan-Guizhou Plateau （YGP） from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility （Vd）, dry extinction, and water vapor over the YGP are analyzed. The results show that 85% of the stations recorded shortening annual sunshine duration, with the decrease rates between -12.2 and -173.7 h/10yr. Results of Mann-Kendall tests indicate that, among the stations with decreasing sunshine duration, 63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s. This decreasing trend has reversed in the early years of the 21st century. The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period. The annual averages of Vd declined from 34 km in the 1960s to 27 km at present. The annual mean dry extinction coefficient trended upward, from 0.176 to 0.190, on the YGP from 1980 to 2005. Analyses of cloud cover, water vapor, atmospheric visibility, and dry extinction coefficient revealed that emitted tropospheric aerosols （including air pollutants） resulting from increased energy consumption over the YGP could be a major Factor influencing the reductions of sunshine duration and atmospheric visibility.

THE CENOZOIC GEORECORDS IN THE NORTHWEST OF YUNNAN AND THE EVOLUTION OF QING—ZANG PLATEAU

The Cenozoic strata are well developed in the northwest of Yunnan Province, where the eastern boundary of Qing—Zang (Qinghai—Xizang) plateau is located. The rich geo\|records in the Cenozoic strata can help us to recapitulate the evolution history of Qing—Zang plateau.1\ The Cenozoic Strata Ninglang Formation (Paleocene—Middle Eocene) is composed of massively bedded conglomerate , mudstone in the lower part, purple thinly bedded—medium bedded fine quartz sandstone and sandy shale in the upper part, 600m thick. Lijiang Formation (Upper Eocene) and Jinsichang Formation (Oligocene): conglomerate, with a little sandstone in lower part, claystone, with a little conglomerate in the upper part. Lijiang Formation unconformably overlies on Ninglang Formation or even older strata, 1500～2000m thick. Shuanghe Formation (Miocene): thinly—massively bedded muddy siltstone, fine sandstone, marl, with several layers of coal. It unconformably overlies on Jinsichang Formation or even older strata, 108m thick. Sanying Formation (Pliocene): Claystone, siltstone, with a little lignite in the middle and upper part, conglomerate at the base, 110m thick, widely spread in the northwest of Yunnan.Sheshan Formation (early Pleistocene): pebbles, sands and clay layers. It unconformably overlies on the older strata, 100～187m thick.Heyunsi Formation (middle Pleistocene): poorly sorted and poorly rounded gravel and sands, 100～347m thick.Upper Pleistocene Series: glaciers—gravel, sands and clays; alluvial—sandy gravel layer(terraces); lacustrine—fine sand, silt and clay layer, 100 m thick.Holocene Series: lacustrine—sand, silt and clay layers; alluvial—sandy gravel layer (terraces), 50m thick.

International Comparison and Implications of Agricultural Development in Foreign Low Latitude Plateau Regions for Yunnan Province

Climatic characteristics of foreign low latitude plateau regions are firstly introduced.Then,experience and lessons of major foreign low latitude plateau countries in developing modern agriculture are analyzed,including Indian three agricultural revolutions and agricultural informationization development,application of agricultural biotechnology in Brazil,trade liberalization and economic de-agriculture of Mexico,and Argentina,Saudi Arabia and South Africa attaching great importance to developing modern agriculture relying on science and technology and paying close attention to resource conservation and environmental protection.Combining natural and social resource characteristics of Yunnan plateau agriculture,pertinent implications and recommendations for modern agricultural development in Yunnan are put forward.Specifically,these include strengthening agricultural sci-tech research and development,and extension and application;transforming agricultural development model;enhancing agricultural resource conservation and environmental protection;accelerating developing mountain organic ecological agriculture and autumn agriculture;reinforcing urban and rural integration to develop plateau characteristic agriculture on the basis of local actual conditions.

Evaluation on the Competitiveness of the Agribusiness with Plateau Characteristics in Yunnan Province Based on AHP

The development of agriculture with plateau characteristics is a market-oriented strategic choice,made by Yunnan Province,of agricultural economy with regional characteristics,on the basis of resources and location advantages,as well as geographical division of the national economy. The characteristic agribusiness is an important carrier for building a new agricultural management system with plateau characteristics,and also a key way to promote characteristic agricultural industrialization. In this paper,with 26 agribusinesses with plateau characteristics in Yunnan Province as samples,we establish the competitiveness evaluation system for the agribusiness with plateau characteristics,and use the operating data( 2012-2014) and AHP to calculate and the sample business competitiveness index and sort these businesses. Finally,we make a comprehensive analysis on the competitiveness of sample agribusinesses with plateau characteristics in Yunnan Province,in order to provide decision-making basis for promotion of the competitiveness of the agribusiness with plateau characteristics.

云南地区强震的超长时间平静异常及未来地震趋势研究

从1996年丽江M_(S)7.0地震发生后至2023年8月,云南地区M≥6.7和M≥7.0地震出现了长达27.55 a的超长时间平静现象。本文从更大时空尺度上对该平静异常现象及其与青藏高原和川滇地块的强震活动之间的关系进行了分析和总结,并讨论了云南地区未来地震趋势。结果表明,1887年以来,云南地区5次M≥7.0地震平静期内其周边地震活动环境有很大差异性:第Ⅰ,第Ⅱ和第Ⅴ平静期出现在青藏高原M≥7.0地震活跃背景下(即云南地区平静,但青藏高原活跃),第Ⅲ和第Ⅳ平静期出现在青藏高原M≥7.0地震平静背景下(即云南地区平静,青藏高原也平静)。当前云南地区处于27.55 a超长时间平静期(即第Ⅴ平静期),其所处的周边地震活动环境与第Ⅰ和第Ⅱ平静期相似,据此推断,其后续地震趋势可能也与第Ⅰ和第Ⅱ活跃期相似,处于相对弱的活跃期。同时,未来较长时间青藏高原可能仍将处于M≥7.0地震活跃时段;2022年泸定M_(S)6.8地震后,川滇地块可能会进入M≥6.7地震活跃时段。

不同气候区生态系统服务权衡空间异质性及其驱动因素——以川滇-黄土高原生态屏障带为例

厘清生态系统服务权衡关系的驱动因素对实现生态系统高效管理至关重要。然而,在不同气候区生态系统服务权衡关系在空间上如何变化及其驱动机制是否一致,尚不清楚。以川滇-黄土高原生态屏障带为例,基于InVEST模型、CASA模型评估生态系统服务空间分布特征,采用RMSE量化生态系统服务权衡关系,利用地理探测器探究不同气候区生态系统服务权衡的驱动机制,以期为生态系统管理提供参考依据。结果如下:(1)不同生态系统服务在不同气候区存在明显差异,WY整体由东北向西南呈递减趋势,NPP和SC呈现由北向南递减的趋势。(2)WY∩NPP的权衡最高值在中温带为0.317,最低值在高原气候区为0.181。WY∩SC在不同气候区RMSE变化幅度较小,由南向北呈现递减趋势;中亚热带气候区WY∩SC的权衡程度最高,为0.295,南温带的权衡程度最低,为0.229。NPP∩SC的RMSE差值最小,仅有0.064,高原气候区权衡程度略低于温带和亚热带。(3)在不同气候区自然因素对权衡关系作用显著高于社会因素,但在人口密集区,人为活动可以部分突破自然因素的约束,使其对权衡的影响有所提升。因此,在制定不同气候区生态系统服务管理的针对性措施时,应考虑生态系统服务权衡的空间特征和驱动因素的差异性。

滇中元江栲林下土壤活性有机碳空间分布特征

为探究滇中元江栲林下土壤活性有机碳在垂直空间上的分布及其影响机制,以滇中地区不同海拔(2090~2490 m)、不同坡向(阴、阳坡)元江栲林为研究对象,探究林下0~60 cm土层土壤有机碳(SOC)、微生物量碳(MBC)、可溶性有机碳(DOC)、易氧化有机碳(ROC)、颗粒性有机碳(POC)含量的空间分布特征。结果表明:SOC、MBC、ROC、POC含量随海拔上升先升高再降低,DOC含量随海拔上升逐渐降低,4种活性有机碳组分含量表现为POC>ROC>MBC>DOC。4种土壤活性有机碳含量均阴坡高于阳坡,且随土层深度增加呈明显下降趋势,0~20 cm土层高于20~40、40~60 cm土层。各个土壤活性有机碳组分在土壤有机碳中的占比表现为POC/SOC>ROC/SOC>MBC/SOC>DOC/SOC,POC为4种活性有机碳库中的主要碳库,MBC/SOC比值随海拔上升无明显变化规律,ROC/SOC、POC/SOC比值随海拔上升先增大再减小。SOC、MBC、ROC、POC含量任意两者间均呈极显著正相关(P<0.01),土壤活性有机碳含量与土壤pH值呈极显著负相关(P<0.01)。海拔与土层极显著影响SOC、DOC、MBC、ROC、POC含量(P<0.001),坡向极显著影响SOC、POC含量(P<0.01,P<0.001),显著影响DOC含量(P<0.05)。

近红外高光谱传感器在地震有关气体监测中的应用:以青藏高原东边界为例

为了促进高光谱技术在地震有关气体监测中的应用,本文选取对近地表信息敏感度较强的近红外高光谱传感器TROPOMI的二级产品数据,分析研究了青藏高原东北缘和川滇地区地震相关气体时空特征及其与构造和地震活动关系,评价了近红外传感器在地震有关气体监测中的应用效果和应用前景。结果表明:TROPOMI反演的研究区CH_(4)和CO气体在时间上呈现明显的季节变化,受气候变化、地貌、人类活动等影响;空间上在银川、渭河和四川盆地表现为高值,受地质背景、地形地貌和人类活动等因素影响。目前近红外高光谱传感器在时间分辨率和有效数据量上具有一定的局限性,但是相对于热红外高光谱传感器,近红外传感器可以较好地反映气体与近地表构造的关系。未来随着近红外高光谱传感器的应用和发展,近红外数据可以逐渐弥补热红外传感器数据对近地表信息敏感度低的不足,提高异常与地震关系的判断力。

云贵高原典型区域气象灾害时空演变特征及影响因素分析

目前气象灾害研究主要以时空分布规律和典型气象灾害风险评估为主,在对气象灾害进行系统的时空演变及影响因素研究方面还相对薄弱。为了揭示云贵高原典型气象灾害时空演变特征及影响因素,本研究基于大理州1984~2021年的历史气象灾害灾情统计数据,利用Arc GIS的标准差椭圆法、新兴时空热点分析和地理探测器,分析了大理州气象灾害时空演变特征及影响因素。结果表明:(1)时间上,大理州气象灾害集中发生在5~9月,历史气象灾害时间在年际变化上可分为三个阶段;(2)空间上,气象灾害发生密度较高的县(市)主要分布在大理市和鹤庆县;(3)时空变化上,5~7月气象灾害中心集中分布在大理市,移动方向为先北再西南后向北移动,鹤庆县出现新增热点;(4)地理探测器结果显示,24 h累计降水量、坡度和河网密度是引起暴雨洪涝灾害的主要原因。研究成果有助于认识大理州气象灾害的时空演变趋势和主要影响因素,从而为气象灾害防治工作提供技术支撑与理论指导。

川滇高原高寒草甸生态系统不同功能群植物分布格局的MaxEnt模型预测

为探究青藏高原高寒草甸生态系统不同主要功能群适宜生境的空间分布格局、主控气候因子及在气候变化背景下的变化趋势,基于青藏高原第2次科考数据(2019-2021年),利用MaxEnt模型预测川滇高原高寒草甸生态系统主要功能群的4种典型物种(莎草科-矮嵩草;禾本科-垂穗披碱草;杂类草-鹅绒委陵菜;豆科-异叶米口袋)在未来气候变化条件下空间分布格局及影响其分布的主要气候因子。结果表明,矮嵩草、垂穗披碱草、鹅绒委陵菜和异叶米口袋在当前气候条件下的适宜生境面积分别为11.09万、9.23万、17.12万和16.53万km^(2),主要位于川滇高原中部和北部区域。环境因子贡献率和响应曲线显示,4个物种生境适宜性对生存环境具有相似的生态要求,且影响其分布的主要气候因子均为气温年较差、等温性和年均温等与温度有关的环境因子。在未来气候背景下,4个物种适宜生境面积均呈扩张趋势且平均海拔均升高了100~200 m,但变化速率趋于减缓,高寒草甸生态系统的物种多样性、生物量和稳定性可能随着气候变化而增强。

云南高原金沙江干支流水沙相关性分析

云南省境内的金沙江流域覆盖全省主要的经济、政治地域,金沙江虎跳峡河段是正在开工建设的滇中引水工程的水源区,分析云南高原金沙江干支流水沙相关性对揭示区域水沙规律、保障水源安全具有重要意义。为此,基于云南省境内金沙江流域干流及典型支流上的控制站点的流量和悬移质含沙量等观测资料,依托随机水文、趋势分析、Copula函数等方法系统地分析了水沙年际年内分布、时空遭遇、协同变化等规律和特性。结果表明,云南省境内金沙江干、支流流量和悬移质含沙量的年内分配不均,流量和悬移质含沙量正相关变化不完全同步;流域发生连续丰水/多沙事件的概率大于连续枯水/少沙事件的概率,但前者的持续影响弱于后者;水沙遭遇异步概率大于同步概率,丰水多沙组合的同现重现期最大、联合重现期次之、条件重现期最小。

贵州省云贵高原型中蜂形态多样性分析

从贵州省4个县12个采样点117群中华蜜蜂中,每群随机采集15只工蜂,对每只工蜂进行29项形态指标的测定。利用SPSS19.0对形态特征数据进行因素分析、聚类分析和变异分析。因素分析提取了3个特征值较高的因素,包括了76.44%的变异。利用提取的主因子进行聚类分析,可将其分为4个类群:威宁雪山、黑石头镇为一类,纳雍姑开乡、新房乡、水东乡、羊场乡和赫章野马川镇、平山镇为一类,正安芙蓉江、和溪镇为一类,威宁石门、草海为一类,说明贵州省境内中蜂存在形态差异及种群分化;变异分析结果显示贵州省12个采样点中华蜜蜂29项形态指标样点间差异较大,其中,黑石头镇、雪山镇在前翅长和前翅宽两个指标及吻长、股节长、基节长等与个体大小相关指标平均值较大,均与其他地区存在显著性差异(P<0.05)。该研究为贵州省中蜂资源的研究提供了理论基础数据,对开发和利用蜜蜂资源具有重要意义。

滇中高原哀牢山不同林分土壤重金属污染特征及其生态风险评价

为探究滇中高原哀牢山不同林分类型土壤重金属的分布特征及对其潜在生态风险进行评价,选取哀牢山4种林分(常绿阔叶林、高山栎林、华山松林、滇油杉林)土壤为研究对象,采集林分土壤,对该土壤进行7种重金属(Zn、Cu、Mn、Cr、Pb、As、Ni)、有机质含量和pH进行检测分析。以云南省土壤背景值和国家土壤环境质量标准(Ⅰ级)作为参比值,采用Hakanson潜在生态危害指数法(Potential ecologicalrisk index)评价研究区不同林分土壤重金属潜在生态危害效应。结果表明,研究区内土壤中Zn的含量最高,其次是Mn,其余5种都在5 mg/kg以下,pH均为酸性,有机质的含量常绿阔叶林最高,滇油杉林、华山松林次之,高山栎林最低,变异系数为18.32%~37.26%。常绿阔叶林土壤中Pb和pH为显著负相关(P<0.05),与有机质显著正相关(P<0.05);高山栎林Pb和Ni极显著负相关(P<0.01),As和有机质显著正相关(P<0.05);华山松林Mn与Pb显著正相关(P<0.05);滇油杉林Zn和Pb、Ni、有机质为负相关外,其余4种重金属和pH均为正相关,且相关性均不显著(P>0.05);有机质与Zn的相关性较强可聚类为一组。4种林分土壤重金属的单种和多种土壤重金属潜在生态危害都处于轻微风险状态,单种重金属潜在生态危害程度平均值由大到小排序为As、Zn、Ni、Pb、Cu、Cr、Mn,多种土壤重金属潜在生态危害程度由大到小排序为华山松林、滇油杉林、常绿阔叶林、高山栎林。

云南高原矿区土壤速效钾含量的测定

从送检的分布在云南高原矿区土壤样品中速效钾含量来看,样品间差距较大,呈现跳跃性,且样品中基体干扰明显。该方法检出限为0.02 mg/kg,检测下限为0.05 mg/kg,实验选取标准物质测试结果的相对标准偏差RSD在1.18%~2.52%之间,相对误差RE(%)最大仅为2.42%;随机选取的4件实际样品的回收率在95.0%~102.6%之间;对云南高原矿区的184件土壤样品进行测试分析,随机安插国家一级标准物质质控样合格率为98.2%,远高于同行业其他方法;利用火焰原子吸收光谱法测定云南高原矿区土壤中速效钾,可实现成批量测定,该方法灵敏度高、分析速度快、操作简便,且结果稳定、准确、可靠。

云南省九湖流域低污染水总量、类型及利用现状分析

为有效推进云南省九湖流域低污染水资源化利用,基于九湖流域2021年的城镇污水处理厂、气象和农业灌溉相关数据,分别从城镇污水处理厂尾水和农田径流排水水量2个方面计算九湖流域2021年低污染水总量,并结合实际调查对其利用现状进行分析。结果表明:1)九湖流域内产生的低污染水总量为150736.07万m^(3),其中城镇污水处理厂尾水水量为82544.14万m^(3),农田径流排水水量为68191.93万m^(3)。2)九湖流域低污染水回用总量为46279.44万m^(3),回用率为30.70%。城镇污水处理厂尾水回用率为54.46%,其中滇池流域回用率最高,其尾水主要用于景观用水,其次是农业灌溉和城市杂用;农田径流排水回用率为1.94%,主要是通过建有调蓄带的洱海、抚仙湖、杞麓湖、星云湖等流域实现回用,其中星云湖流域农田径流排水回用量最高。3)九湖流域低污染水回用还有很大空间,不同湖泊流域可根据产业结构及发展定位设立不同的低污染水回用目标,加强对农田径流排水的水质监测;根据不同时期农田径流排水水质,科学合理确定农田径流排水用途和去向,充分利用调蓄带的拦蓄储存净化功能,加强污水处理厂尾水、农田退水、初期雨水之间的综合利用。建议在九湖流域内选择典型地区开展低污染水利用配置试点工作,通过试点示范总结成功经验,形成可复制、可推广的低污染水资源化利用模式,促进流域内低污染水资源回用。

A Study of Influencing Systems and Moisture Budget in a Heavy Rainfall in Low Latitude Plateau in China during Early Summer

Analysis of a heavy rainfall in a lower latitude plateau and characteristics of water vapor transportation have been conducted by using conventional data and denser surface data. The results show： （1） the heavy rainfall was caused by a series of mesoscale systems under favorable large-scale conditions when the warm moister air and cold air interacted with each other. At the same time, the coupling between the upper- and lower-level jets was revealed. It is also found that there exists some different characteristics among the main influencing systems of heavy rainfalls in Yunnan, such as the Indian-Myanmar trough and the path of the cold air, compared with those in East and South China. （2） The interaction between mesoscale convergence lines near the ground may be a possible triggering mechanism for the occurrence of mesoscale systems, and the dynamical and thermal dynamical structure of the mesoscale systems was very obvious. The convergence lines may relate closely to the terrain of Yunnan, China. （3） The computation of the water vapor budget reveals that the primary source of water vapor supply for heavy rainfall was in the Bay of Bengal. In this case, the water vapor could be transported into Yunnan even though the amount of water vapor was less than that in the lower troposphere in East and South China. In addition, the analysis for three-dimensional air parcel trajectories better revealed and described the source location and the transportation of water vapor to Yunnan.