若尔盖高原湿地不同微地貌区甲烷排放通量特征

若尔盖高原是我国泥炭沼泽湿地的主要分布区、青藏高原的主要甲烷(CH₄)排放中心。为了研究湿地微地貌环境对高原湿地CH₄排放通量的影响, 2014年5-10月, 采用静态箱和快速温室气体分析仪原位测量若尔盖高原湖滨湿地3种泥炭沼泽5种微地貌环境下的CH₄排放通量特征。结果表明: (1)常年性淹水泥炭湿地洼地(P-hollow)和草丘(P-hummock)生长季平均CH₄排放通量为68.48和40.32 mg·m^-2·h^-1, 季节性淹水的泥炭湿地洼地(S-hollow)和草丘(S-hummock)平均CH₄排放通量为2.38和0.63 mg·m^-2·h^-1, 而无淹水平坦地(Lawn)平均CH₄排放通量为3.68 mg·m^-2·h^-1; (2)湿地5种微地貌区CH₄排放通量为(23.10 ± 30.28) mg·m^-2·h^-1 (平均值±标准偏差)), 变异系数为131%。分析显示这5种微地貌区CH₄排放通量的平均值与其水位深度平均值存在显著的线性正相关关系(R² = 0.919, p < 0.01), 表明水位深度是控制湿地微地貌区CH₄排放通量空间变化的主要因子; (3) P-hummock、P-hollow和S-hummock的CH₄排放通量存在显著的季节变化, Lawn和S-hollow无明显的季节性变化, 但5种微地貌区在夏季或秋季均观测到CH₄排放通量峰值, 其影响因子可能与水位深度、土壤温度和凋落物输入密切相关; (4) P-hollow可能时常发生冒泡式CH₄排放, 这可能导致过去低估了若尔盖高原湿地的CH₄排放量。     

云雾山草坡和泾川刺槐林坡面土壤电阻率和含水率的空间差异

采用盆栽控水的方法,研究干旱胁迫（80%FC、60%FC、40%FC和20%FC）及施氮（N0 0 g·pot-1、Nl 1.2 g·pot-1、Nm 3.6 g·pot-1和Nh 6.0 g·pot-1）对麻疯树幼苗叶、茎和根部主要渗透调节物质积累的影响.结果表明： 干旱胁迫条件下,麻疯树幼苗茎和根部的游离脯氨酸、可溶性蛋白和茎部可溶性糖大量积累,叶片中脯氨酸含量也随干旱胁迫程度的增加大幅度上升;Na+、Ca2+和Mg2+在麻疯树幼苗叶、茎和根中大量积累,而K+仅在茎中大量积累,叶片和根部K+含量略微上升.施氮对植株渗透调节物质的影响与干旱胁迫强度和施氮水平有关.在80%FC和60%FC水分条件下,增加N肥施用量能明显促进麻疯树幼苗各组分渗透调节物质的积累;在40%FC水分条件下,Nh处理对渗透调节物质积累的促进作用减弱;而在20%FC条件下,Nl处理植株的渗透调节能力较高,Nm和Nh处理对植株渗透调节的促进作用不明显甚至转为抑制.     

Mitochondrial and chloroplast phylogeography of Picea crassifolia Kom. (Pinaceae) in the Qinghai-Tibetan Plateau and adjacent highlands

The disjunct distribution of forests in the Qinghai-Tibetan Plateau (QTP) and adjacent Helan Shan and Daqing Shan highlands provides an excellent model to examine vegetation shifts, glacial refugia and gene flow of key species in this complex landscape region in response to past climatic oscillations and human disturbance. In this study, we examined maternally inherited mitochondrial DNA (nad1 intron b/c and nad5 intron 1) and paternally inherited chloroplast DNA (trnC-trnD) sequence variation within a dominant forest species, Picea crassifolia Kom. We recovered nine mitotypes and two chlorotypes in a survey of 442 individuals from 32 populations sampled throughout the species' range. Significant mitochondrial DNA population subdivision was detected (G(ST) = 0.512; N(ST) = 0.679), suggesting low levels of recurrent gene flow through seeds among populations and significant phylogeographical structure (N(ST) > GST, P < 0.05). Plateau haplotypes differed in sequence from those in the adjacent highlands, suggesting a long period of allopatric fragmentation between the species in the two regions and the presence of independent refugia in each region during Quaternary glaciations. On the QTP platform, all but one of the disjunct populations surveyed were fixed for the same mitotype, while most populations at the plateau edge contained more than one haplotype with the mitotype that was fixed in plateau platform populations always present at high frequency. This distribution pattern suggests that present-day disjunct populations on the QTP platform experienced a common recolonization history. The same phylogeographical pattern, however, was not detected for paternally inherited chloroplast DNA haplotypes. Two chlorotypes were distributed throughout the range of the species with little geographical population differentiation (G(ST) = N(ST) = 0.093). This provides evidence for highly efficient pollen-mediated gene flow among isolated forest patches, both within and between the QTP and adjacent highland populations. A lack of isolation to pollen-mediated gene flow between forests on the QTP and adjacent highlands is surprising given that the Tengger Desert has been a geographical barrier between these two regions for approximately the last 1.8 million years.     

Areas of endemism and patterns of diversity for aphids of the Qinghai-Tibetan Plateau and the Himalayas

Aim  The study aimed to identify areas of endemism for aphids in the Qinghai-Tibetan Plateau and the Himalayas (QTPH), and to test congruence between patterns of endemism and patterns of overall species richness identified in a previous study.
Location  The QTPH.
Methods  A distribution data base of 326 endemic aphids in the QTPH was compiled. The study area was divided into a grid of 2°× 2° operative geographical units. Parsimony analysis of endemicity (PAE) was used to identify areas of endemism, and the diversity patterns of endemic species were then mapped using GIS.
Results  We identified 326 endemic species belonging to 138 genera within Adelgidae and 14 subfamilies of Aphididae. Five areas of endemism were found using PAE analysis: the eastern Himalayas, the western Himalayas, north-western Yunnan, southern Tibet and the eastern QTPH. Maps of patterns of endemism identified four major centres for endemic aphids, namely the western Himalayas, the eastern Himalayas (or Sikkim-Assam Himalayas), north-western Hengduan Mountains and the mountains of southern Gansu Province, and three minor centres, southern Tibet, south-eastern Tibet and the eastern Qinghai Province in the north-eastern QTPH.
Main conclusions  Our study identifies major centres of aphid endemism. Furthermore, there is a noticeable congruence between patterns of endemism and patterns of species richness. The patterns of endemism were most likely influenced by the recent uplift of the QTPH.     

高寒生态脆弱区农户对气候变化的感知与适应意向——以甘南高原为例

以地处青藏高原东缘的甘南高原为研究区,基于农户调查数据,分析了农户的气候变化感知对其适应意向的影响,为制定有效的气候变化适应政策提供依据.结果表明: 纯农户、兼业户、非农户对气候变化的严重性的感知依次降低,但适应功效感知依次增强,且与非农户、纯农户相比,兼业户的可能性感知、自我效能感知与适应成本感知均较高;纯农户、兼业户、非农户对气候变化的积极适应意向趋于增强;气候变化风险感知、适应功效感知促使农户产生积极适应意向,而适应成本感知促使其产生消极适应意向.同时,农户拥有的耕地面积、牲畜数量、收入水平以及性格乐观程度与积极适应意向发生概率呈显著正相关,而固定资产拥有量、无偿现金援助机会、亲戚网及帮助网规模与其呈显著负相关.最后,提出了促使农户产生积极适应意向的对策建议及未来研究中需关注的问题.     

THIS ARTICLE HAS BEEN RETRACTED: What caused the mid‐Holocene forest decline on the eastern Tibet‐Qinghai Plateau?

Aim Atmospheric CO₂ concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad‐scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north‐eastern Tibet‐Qinghai Plateau reveal a dramatic and extensive forest decline beginning c. 6000 cal. yr bp . The aim of this study is to elucidate the causes of this regional‐scale change from high‐biomass forest to low‐biomass steppe on the Tibet‐Qinghai Plateau during the second half of the Holocene. Location Our study focuses on the north‐eastern Tibet‐Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36°32′–37°15′ N, 99°36′–100°47′ E). Methods We apply a modern pollen‐precipitation transfer function from the eastern and north‐eastern Tibet‐Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen‐isotope record from the same sediment core and to results from two transient climate model simulations. Results The pollen‐based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen‐isotope record. Furthermore, these results are in close agreement with simulated model‐based past annual precipitation changes. Main conclusions In the light of these data and the model results, we conclude that it is not necessary to attribute the broad‐scale forest decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid‐Holocene is the most parsimonious explanation for the widespread forest decline on the Tibet‐Qinghai Plateau. Moreover, climate feedback from a reduced forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation–climate interactions during this major ecological change.     

陇中黄土高原春小麦光谱反射特征

通过田间小区试验,测定了3个春小麦品种(高原602、陇春8139和定西24)在不同生育期和不同种植密度的光谱反射率及对应叶面积指数(LAI)和地上生物量,分析了其光谱反射的一般特征和红边参数特征以及光谱变量与LAI和地上生物量的相关性.结果表明:在整个波段内,春小麦冠层光谱表现为高原602＞陇春8139＞定西24,其叶片光谱表现为定西24＞陇春8139＞高原602;春小麦冠层光谱在可见光波段和中红外波段成熟期明显大于孕穗期,而叶片光谱在近红外波段孕穗期明显大于成熟期;随着种植密度的提高,在近红外波段冠层和叶片的光谱反射率逐渐增加;冠层光谱的红边均具有"双峰"现象,从孕穗期到成熟期,冠层红边位置呈现"蓝移"现象;LAI和地上生物量与冠层光谱变量之间存在较好的相关性.     

青藏高原丽蝇科昆虫物种多样性初探

本文从种数、特有物种和区系构成等角度分析了青藏高原丽蝇科昆虫的物种多样性。青藏高原已知丽蝇5亚科35属120种,占中国已知种数的44.28%,其中特有种55种,占该地区总种数的45.83%;区系构成以特有种、古北界 东洋界共同种及典型的东洋界种和古北界种为主,但澳洲界、新北界、非洲界和新热带界共同种也占一定比例。文中讨论了该地区特有种丰富的原因及地质历史环境对其的影响,分析了区系构成中各种区系成分的比例及形成原因。