Hydrochemical characteristics of surface water in Hengduan mountain region of Eastern Tibet and its response to human activities:A case study of Duoqu Basin,Jinsha River

The analysis of hydrochemical characteristics and influencing factors of surface river on plateau is helpful to study water hydrological cycle and environmental evolution,which can scientifically guide rational development and utilization of water resources and planning of ecological environment protection.With the expansion and diversification of human activities,the quality of surface rivers will be more directly affected.Therefore,it is of great significance to pay attention to the hydrochemical characteristics of plateau surface rivers and the influence of human activities on their circulation and evolution.In this study,surface water in the Duoqu basin of Jinsha River located in Hengduan mountain region of Eastern Tibet was selected as the representative case.Twenty-three groups of surface water samples were collected to analyze the hydrochemical characteristics and ion sources based on correlation analysis,piper trigram,gibbs model,hydrogen and oxygen isotopic techniques.The results suggest the following:(1)The pH showed slight alkalinity with the value ranged from 7.25 to 8.62.Ca^(2+),Mg^(2+)and HCO_(3)^(–)were the main cations and anions.HCO_(3)^(-)Ca and HCO_(3)^(-)Ca·Mg were the primary hydrochemical types for the surface water of Duoqu River.The correlation analysis showed that TDS had the most significant correlation with Ca^(2+),Mg^(2+)and HCO_(3)^(–).Analysis on hydrogen and oxygen isotopes indicated that the surface rivers were mainly recharged by atmospheric precipitation and glacial melt water in this study area.(2)The surface water had a certain reverse cation alternating adsorption,and surface water ions were mainly derived from rock weathering,mainly controlled by weathering and dissolution of carbonates,and secondly by silicates and sodium rocks.(3)The influence of human activities was weak,while the development of cinnabar minerals had a certain impact on the hydrochemistry characteristics,which was the main factor for causing the increase of SO_(4)^(2–).The densely populated county towns and temples with frequent incense burning activities may cause some anomalies of surface water quality.At present,the Duoqu River watershed had gone through a certain influence of mineral exploitation,so the hydrological cycle and river eco-environment at watershed scale will still bound to be change.The results could provide basic support for better understanding water balance evolution as well as the ecological protection of Duoqu River watershed.

Attribution analysis for water yield service based on the geographical detector method:A case study of the Hengduan Mountain region

Ecosystem services,which include water yield services,have been incorporated into decision processes of regional land use planning and sustainable development.Spatial pattern characteristics and identification of factors that influence water yield are the basis for decision making.However,there are limited studies on the driving mechanisms that affect the spatial heterogeneity of ecosystem services.In this study,we used the Hengduan Mountain region in southwest China,with obvious spatial heterogeneity,as the research site.The water yield module in the InVEST software was used to simulate the spatial distribution of water yield.Also,quantitative attribution analysis was conducted for various geomorphological and climatic zones in the Hengduan Mountain region by using the geographical detector method.Influencing factors,such as climate,topography,soil,vegetation type,and land use type and pattern,were taken into consideration for this analysis.Four key findings were obtained.First,water yield spatial heterogeneity is influenced most by climate-related factors,where precipitation and evapotranspiration are the dominant factors.Second,the relative importance of each impact factor to the water yield heterogeneity differs significantly by geomorphological and climatic zones.In flat areas,the influence of evapotranspiration is higher than that of precipitation.As relief increases,the importance of precipitation increases and eventually,it becomes the most influential factor.Evapotranspiration is the most influential factor in a plateau climate zone,while in the mid-subtropical zone,precipitation is the main controlling factor.Third,land use type is also an important driving force in flat areas.Thus,more attention should be paid to urbanization and land use planning,which involves land use changes,to mitigate the impact on water yield spatial pattern.The fourth finding was that a risk detector showed that Primarosol and Anthropogenic soil areas,shrub areas,and areas with slope<5°and 250-350 should be recognized as water yield important zones,while the corresponding elevation values are different among different geomorphological and climatic zones.Therefore,the spatial heterogeneity and influencing factors in different zones should be fully con-sidered while planning the maintenance and protection of water yield services in the Hengduan Mountain region.

Phylogenetic pattern of alpine plants along latitude and longitude in Hengduan Mountains Region

To detect the horizontal pattern of phylogenetic structure shown by alpine plants, we measured phylogenetic structure using net related index(NRI) and net nearest taxon index(NTI), and analyzed the phylogenetic structure patterns of alpine plants along longitude, latitude and environmental gradients in the Hengduan Mountains Region(HDMR). Our results show that: 1) the phylogenetic structure tended to cluster with increasing latitude and longitude; 2) for NRI, latitude was closer related than longitude,while for NTI, longitude was closer related than latitude, though they both not significantly relate to NTI.The phylogenetic structure tended towards overdispersion in the southern HDMR, with good climate conditions of higher mean annual temperature and more mean annual precipitation. In contrast, with harsh climate conditions of lower mean annual temperature and less mean annual precipitation, the increasing environmental stress led to phylogenetic clustering in the northern HDMR. The results highlighted that in the alpine region of HDMR, environmental filters and geographical isolation had a great effect on the latitudinal and longitudinal alpine species distribution, respectively.

Forest disturbances and the attribution derived from yearly Landsat time series over 1990–2020 in the Hengduan Mountains Region of Southwest China

Background:Natural forests in the Hengduan Mountains Region(HDMR)have pivotal ecological functions and provide diverse ecosystem services.Capturing long-term forest disturbance and drivers at a regional scale is crucial for sustainable forest management and biodiversity conservation.Methods:We used 30-m resolution Landsat time series images and the LandTrendr algorithm on the Google Earth Engine cloud platform to map forest disturbances at an annual time scale between 1990 and 2020 and attributed causal agents of forest disturbance,including fire,logging,road construction and insects,using disturbance properties and spectral and topographic variables in the random forest model.Results:The conventional and area-adjusted overall accuracies(OAs)of the forest disturbance map were 92.3% and 97.70%±0.06%,respectively,and the OA of mapping disturbance agents was 85.80%.The estimated disturbed forest area totalled 3313.13 km^(2)(approximately 2.31% of the total forest area in 1990)from 1990 to 2020,with considerable interannual fluctuations and significant regional differences.The predominant disturbance agent was fire,which comprised approximately 83.33% of the forest area disturbance,followed by logging(12.2%),insects(2.4%)and road construction(2.0%).Massive forest disturbances occurred mainly before 2000,and the post-2000 annual disturbance area significantly dropped by 55% compared with the pre-2000 value.Conclusions:This study provided spatially explicit and retrospective information on annual forest disturbance and associated agents in the HDMR.The findings suggest that China’s logging bans in natural forests combined with other forest sustainability programmes have effectively curbed forest disturbances in the HDMR,which has implications for enhancing future forest management and biodiversity conservation.

A new scheme of climate-vegetation regionalization in the Hengduan Mountains Region

The Hengduan Mountains Region(HMR) is essential for the future ecological protection, clean energy production,Sichuan-Xizang and Yunnan-Xizang railways, and other major infrastructure projects in China. The distributions of climate and vegetation exhibit significant regional differentiation and vertical zonality due to the rugged longitudinal ranges and gorges and the complex disaster-prone environments in HMR. Therefore, it is urgent to develop the climate-vegetation regionalization in HMR to effectively satisfy the national requirements such as agricultural production and ecological protection, mountain disaster risk prevention, and major project construction. We here develop a new scheme of climate-vegetation regionalization with the latest demarcation outcome of HMR, the ground observation from 122 meteorological stations in HMR and its surrounding areas during 1990–2019, and the high-precision remote sensing data of land cover types. The new scheme first constructs the regionalization index system, fully considering the extraordinarily complicated geomorphic pattern of mountains and valleys, the scarcity of meteorological observations, and the remarkable differentiation of climate and vegetation in HMR. The system consists of three primary regionalization indices(i.e., days with daily average temperature steady above 10°C, aridity index, and main vegetation types, dividing the temperature zones, moisture regions, and vegetation subregions, respectively) and three auxiliary indices of the accumulated temperature above 10°C, and the temperatures in January and July. Then, the HMR is divided into five temperature zones, 20 moisture regions, and 55 vegetation subregions. Compared with previous regionalization schemes, the new scheme optimizes the climate spatial interpolation model of thin plate smoothing spline suitable for the unique terrain in HMR. Moreover, the disputed division index threshold between different climatic zones(regions) is scientifically clarified using geographical detectors. Specifically, the stepwise downscaling pane division method is initially proposed to determine the zoning boundary, alleviating the excessive dependence of the traditional zoning method on subjective experience.Besides, the scheme considers the typical regional characteristics of the complex underlying surface and the high gradient zone of climate-vegetation distribution types in HMR. Consequently, the transition zone with quick climate changes between the plateau temperate and mid-subtropical zones is divided into mountainous subtropics, taking into account the spatial distribution characteristics of climate-vegetation regionalization indices. The regionalization scheme will provide practically theoretical support for agricultural production, ecological protection, major project construction, disaster prevention and relief efforts, and other socioeconomic activities in HMR, serving as a classic case of climate-vegetation regionalization for the alpine and canyon regions with intricate underlying surface, striking regional differences, and lack of ground observations.

ECMWF模式对我国西南环横断山区冬季近地面2m温度的预报评估

从冬季平均温度、温度日变化及日较差等方面入手,基于2021年CLDAS逐小时产品评估了ECMWF全球高分辨率确定性数值预报产品对我国西南环横断山区复杂地形区近地面2 m温度的预报能力,并通过区分高地形区(川西高原)和低地形区(四川盆地南部),对比了不同地形区近地面2 m温度预报的偏差特征。结果表明:(1)ECMWF模式可合理预报我国西南环横断山区冬季平均2 m温度的空间分布特征,但偏差分布与地形高度有关,随着地形高度的增加,预报偏差呈增大趋势。(2)ECMWF模式很好再现了西南环横断山区冬季温度的日变化特征,峰值时刻出现在14:00(北京时);各时刻温度的预报偏差在不同地形高度存在差异,川西高原和横断山区的最大负偏差出现在下午,四川盆地南部的最大负偏差出现在早晨。同时,高地形区各时刻的预报偏差均高于低地形区。(3)ECMWF模式对日内各时刻不同地形处2 m温度的空间分布均有合理预报,但偏差存在日变化特征。特别是在横断山区高地形区,其在各时刻有不同的冷暖偏差特征。(4)在环横断山区温度日较差预报偏差较大的区域(大致为昆明准静止锋线发生频次较高的区域),模式对于温度日较差较大的日数,其2 m温度的预报偏差要大于日较差较小的日数,且在该区域内,温度日较差的预报偏差相对不稳定。

横断山区东部四种林型地表甲虫的物种多样性

20 0 1年 7月 8～ 1 4日在横断山区东部选择皆伐后经过管理的人工次生林 (MSF)、无人管理的农耕区次生林 (USF)、邻近天然的冷杉林 (NAF)和杜鹃矮曲林 (NRF) 4种林型 ,共设置样地 2 0块 ,以巴氏罐诱法收集地表甲虫的物种组成和数量数据 ,并以地表甲虫的种类和数量分布为属性做主成分分析和聚类分析 ,研究森林皆伐和管理行为对地表甲虫物种多样性的影响。共采集地表甲虫标本 4 2 92号 ,步甲科、觅葬甲科和隐翅虫科分别占总数 4 6 8%、 1 3 1 %和 1 1 4 % ,是数量最多的类群 ;金龟科、象甲科和拟步甲科的数量也各在5 %以上 ,为常见类群。其中 ,步甲科的个体数量在NRF显著多于其他林型 ,在USF显著少于其他林型 ;觅葬甲科在两个天然林显著多于两个次生林 ;拟步甲科在NRF显著多于其他林型 ;花萤科在MSF和NAF显著多于USF ;叩甲科在USF显著多于MSF和NAF ;象甲科在NRF和MSF明显多于USF ;叶甲科在NRF明显多于USF。地表甲虫的个体数量从USF、MSF、NAF到NRF逐渐增多 ,而均匀度指数则逐渐降低 ;MSF内物种丰富度和多样性指数分别显著高于USF和NRF。主成分分析和聚类分析表明 ,除了USF与其他林型有明显差异外 ,其他林型间有一定的相似性 ,但MSF与天然NAF间相似性较低。以上结果表明 。

横断山区气温和降水年季月变化特征

为详尽分析横断山区气候变化过程,利用横断山区内90个气象站点的1961—2011年气温和降水资料,采用线性趋势、Mann-Kendall非参数趋势和突变检验法、反距离加权插值法等方法研究了横断山区气温和降水年、季、月的多时间尺度下的变化规律和变化趋势的空间分布情况。结果表明:1961—2011年横断山区气温以0.16℃/10 a的速率显著升高,降水以11.41 mm/10 a的速率呈现不显著的递减趋势,说明横断山区呈现变暖变干的趋势,2000年以后暖干趋势尤为明显。从气温和降水的变化趋势的空间分布来看,气温升温趋势北部比南部剧烈,西部比东部更为剧烈,降水减少趋势呈现南部比北部更剧烈。1961—2011年横断山区春夏秋冬四季气温分别以0.09、0.14、0.16和0.27℃/10 a的速率显著升高。夏、秋、冬季降水分别以-7.88、-8.90、-2.61 mm/10 a的速率呈不显著减少的趋势,春季降水以7.34 mm/10 a的速率显著增加。1961—2011年横断山区全年12个月的气温都呈升高趋势,1—5月降水呈现增加趋势,6—12月减少。分析表明在大气环流发生异常(北极涛动、南极涛动、东亚夏季风、西太平洋副高、南亚高压和海温)和人类活动的共同影响下,横断山区气候呈现暖干的趋势。研究结果为把握横断山区对全球气候变化的响应程度,水资源的合理开发利用提供依据。

横断山区蚜虫区系的组成和特点

研究了横断山区蚜虫区系的组成和特点。横断山区共有蚜虫 11科 6 9属 12 5种 ,以东洋区、特有种类占优势。蚜虫区系古北成分和东洋成分充分交融 ,特有种类丰富 ,区系组成复杂多样。对该区蚜虫的分布进行了初步分析 ,特有种分布不均衡 ,水平主要分布在滇西北的丽江和玉龙雪山地区 ,垂直分布在海拔 30 0 0～ 32 0 0m ,是特有种丰富度最高的地带。此外 ,对跨古北和东洋区分布种类的东亚起源进行了初步探讨。

横断山脉大绒鼠最大代谢率的季节性差异

最大代谢率对于动物的生存、繁殖和分布具有关键作用。实验用开放式呼吸仪测定了大绒鼠(Eothenomys miletus)夏季和冬季的冷诱导最大代谢率和运动最大代谢率。大绒鼠夏季的冷诱导最大代谢率O2为(7.24±0.61)ml/(g.h),运动最大代谢率O2为(7.69±0.59)ml/(g.h);冬季的冷诱导最大代谢率O2为(8.61±0.42)ml/(g.h),运动最大代谢率O2为(7.51±0.51)ml/(g.h)。冷诱导最大代谢率冬夏之间具有差异显著,而运动最大代谢率则差异不显著。结果表明:栖息于横断山脉的大绒鼠由于受到低温的胁迫,导致其冷诱导最大代谢率季节性变化较大,而运动最大代谢率则相对稳定。

横断山区三种小型哺乳动物代谢特征的研究进展

代谢率是生理生态学中的重要指标,能反映不同物种和个体之间的能量消耗水平,在动物适应环境的过程中具有重要的意义,各种不同的物理和生物因素都可能影响到动物的代谢特征。本文综述了体重和温度对横断山区小型哺乳动物中缅树鼩、大绒鼠和高山姬鼠代谢率的影响,比较了3种小型哺乳动物与其它地区小型哺乳动物的异同点,并给出了横断山区小型哺乳动物一些特殊的代谢特征。最后,通过比较代谢产热特征探讨了中缅树鼩的起源问题。

白龙江中上游林区种子植物物种多样性与区系特征

在收集已有文献资料和补点调查的基础上,对白龙江中上游林区天然分布的种子植物进行了物种多样性和区系统计分析.结果表明:本区天然分布的种子植物共计有1 528种,1亚种,80变种,6变型,归属于115科,519属,其中木本植物565种;该区种子植物区系由多种地理成分组成,以温带成分占据绝对优势,温带分布属占75.1%,温带分布种占72.9%,表现出明显的区系过渡性;本区应划归中国-喜马拉雅森林植物亚区、横断山脉地区.

横断山区蚜虫区系的特异性与历史渊源

文章系统分析了横断山区蚜虫区系的特异性,主要表现在:区系成分的复杂性、古北与东洋成分的交融性、区系组成的特有性和物种分布的间断性。进一步结合地质历史事件对横断山区蚜虫区系的历史渊源及其特异性演化进行了初步讨论。根据蚜虫类分布特点,建议古北区和东洋区在横断山区的分界线南移至丽江一线;横断山区蚜虫和其他地区的间隔分布可能是由地质历史上板块运动和青藏高原的隆升及第四纪冰期-间冰期的循环往复造成的;横断山区蚜虫区系是一个复合区系,同其他动物地理区划如新北区、澳洲区、非洲区等的蚜虫区系都有密切的历史渊源,青藏高原和横断山区的隆起及第四纪冰期-间冰期的循环往复又使得本区蚜虫区系有着独特的演化历程,从而造成了本区蚜虫区系的特有性。

横断山区土壤资源可持续利用研究

在分析横断山区土壤资源特点及开发利用中存在问题的基础上,针对性地提出可持续利用途径:以河谷为主,发展生态特色农业;以生态建设为重点,发展多功能林业;强化草地建设和管理,发展商品性草地牧业;加强自然保护区建设,保护生物多样性,发展生态旅游业。

基于InVEST模型的横断山区产水量模拟

[目的]掌握横断山区产水量及水源分布空间。[方法]利用In VEST模型评估计算2005—2014年横断山区年均产水量,分析产水量的空间分布特征及其原因。[结果]横断山区年均产水量为1 723.3亿m3,与自然径流量较为接近;产水量的空间分布总体呈现出自西北向东南递增的趋势;年均产水量及其空间分布特征与研究区土地利用/覆被类型、土壤深度、地势等因素存在密切关系。[结论]该研究可为横断山区水文过程进一步研究提供基础资料,同时为区域水资源管理提供科学依据。

横断山区北段山地土壤基本属性的坡向分异

研究了横断山区北段金沙江以东雀儿山至二郎山等山地土壤属性的坡向性分异规律。结果表明,山地迎风坡由于水分条件优于背风坡,其土壤的生物积累和盐基风化淋溶一般强于背风坡,主要表现在迎风坡土壤的有机质和全氮含量、表层土壤全磷含量、阳离子交换量和速效钾含量高于背风坡土壤;迎风坡土壤的pH、盐基饱和度和基带土壤的钙化及碱性化程度低于背风坡土壤。这种分异在水平方向上,二郎山最为显著,由此向西至雀儿山随季风势力的减弱而减小;在垂直方向上,一般在山麓基带土壤最为明显,沿山体向上至山脊,两坡间的差异逐渐减小甚至趋同。山地迎风坡与背风坡土壤属性的分异,主要源于气候水分因素,有别于主要源于气候热量因素的垂直地带分异,同时也不同于山地土壤属性的阴阳坡分异。

横断山北部高山区不同生态条件下土壤微生物数量及其与生态因子的相关性

采用全球定位系统(GPS)采集了横断山北部高山区35个样点的土样,用稀释平板法对该区细菌、真菌和放线菌进行分离计数,并分析了微生物数量与土壤养分、土壤水分、土地利用方式和pH等因子的相关性。结果表明,该区域3大类土壤微生物数量表现为细菌>放线菌>真菌。土壤微生物数量在不同区域表现为松林口>雀儿山>折多山;林地微生物比草地丰富,但不及草地微生物均衡。微生物数量与土壤理化因子间的相关分析表明,放线菌数量与pH呈显著正相关,真菌数量与土壤全钾含量呈极显著正相关。

横断山区植被绿度的时空变化特征及其成因

科学认识植被绿度变化的时空格局及驱动因子是生态系统管理的基础.横断山是我国西南地区的重要生态屏障,对我国中西部地区的气候及生态环境有着深远影响.本文基于MODIS NDVI数据,采用趋势分析法、偏相关分析及复相关分析等方法,系统分析了2001—2016年横断山区植被NDVI的变化特征及其驱动因子.研究结果显示:2001—2016年横断山区NDVI年均值呈增加趋势,年均增长率为4.4×10-4 a-1.除夏季NDVI均值表现为降低趋势外,其它季节NDVI均值均为增长趋势,增速冬季>春季>秋季.海拔4000 m以下植被NDVI年均值介于0.45~0.55,其增速的海拔梯度差异较小(±0.001 a-1);海拔4000 m以上随海拔梯度的增加,NDVI年均值降低而其增速升高.横断山区植被NDVI变化受气候因子影响的面积仅为16%,大部分地区NDVI变化受CO2浓度增加及土地利用变化等人类活动的影响.研究结果为横断山区生态保护和可持续发展提供参考依据.

食物质量对横断山区高山姬鼠肥满度的影响

为了研究食物质量对横断山区高山姬鼠肥满度的影响,将成年雄性高山姬鼠分别驯化于高、低脂肪及高、低纤维和高、低蛋白食物条件下,驯化结束后测定动物的体重和体长.采用体重与体长立方的比值(K=100×W/L3)作为测定肥满度的指标.结果发现:高、低脂食物对高山姬鼠的肥满度无显著影响;与低纤维或低蛋白食物饲养组相比,高纤维或高蛋白食物饲养高山姬鼠后,其肥满度逐渐减小,4周后达到显著水平,转喂低纤维或低蛋白食物1周后,恢复到对照组水平.高山姬鼠的肥满度在不同食物质量条件下的变化模式与其生存的低纬度、高海拔、年平均温度较低、食物波动大的横断山区密切相关.

横断山区综合自然区划纲要

横断山区地域分异明显。各自然地理要素作地带性组合,自然地理环境呈水平分异,农业土地利用也大体呈纬向带状分布。根据温度和水分条件的地域组合及地势差异,将横断山区划分为5个自然地带、9个自然区,并与以往的方案进行了比较,阐述了自然地带界线的划分及各带特征。