Patterns of plant diversity at high altitudes on the Qinghai-Tibetan Plateau

Aims To describe the biodiversity patterns of plants along an altitudinal gradient on the Qinghai-Tibetan Plateau and to clarify the bias in plant specimen records at high altitude.Methods We conducted a large-scale investigation of vegetation at a wide range of altitudes, focusing on a high-altitudinal range (3?200–5?200 m) at different locations on the Qinghai-Tibetan Plateau. We then compared the altitudinal distribution of plant species obtained from our field investigation with that in plant specimen records from published sources and an online database.Important findings Our data provide evidence that altitude plays a large role in regulating species composition on the Qinghai-Tibetan Plateau. We could not, however, detect a clear relationship between altitude and species richness, although a weak monotonically increasing trend of richness was detected with increasing altitude. According to specimen records, most species have been sampled at a wide range of altitudes, and the average range of 145 species is>2?000 m. Despite this wide range, more than half of the species we observed were at higher altitudes than the specimen records indicate. High-altitude areas have probably been so poorly sampled that only a small fraction of the resident species has been recorded. This study clearly shows the regional bias of specimen records in the Qinghai-Tibetan Plateau.     

高寒草甸退化对土壤昆虫多样性的影响

土壤昆虫是陆地生态系统的重要组成部分,在物质循环和能量转化过程中起着重要的作用。为了查明高寒草甸生态系统退化对土壤昆虫群落的影响,于2011年的4、5、7和10月份别对青藏东缘的若尔盖高寒草甸的沼泽草甸、草原草甸、中度退化草甸和重度退化草甸的土壤昆虫群落进行了调查。共捕获土壤昆虫4172只,隶属于8目35科,共46类。优势类群有尖眼蕈蚊科幼虫(Sciaridae larvae)、摇蚊科幼虫(Chironomidae larvae)和象甲科幼虫(Curculionidae larvae),其中尖眼蕈蚊科幼虫为各退化阶段的共同优势类群。重度退化草甸的土壤昆虫密度和多样性指数均显著低于其它退化阶段(P0.01)。各退化阶段间的Sorenson相似性和Morisita-Horn相似性指数变化趋势表明退化对土壤昆虫的类群组和优势类群的个体数量影响较大。而土壤昆虫的群落密度和多样性指数的季节动态在不同退化阶段间也存在差异。此外,高寒草甸的退化还可影响昆虫群落优势类群的时空分布,但不同类群间存在差异。相关分析结果表明土壤昆虫多样性与土壤p H值呈显著负相关(P0.01),与地下生物量和磷含量呈显著正相关(P0.01),而密度仅与p H值呈显著负相关(P0.01)。研究结果表明高寒草甸退化可通过改变植物群落及土壤等环境因子影响土壤昆虫群落组成和多样性的空间分布和季节动态。     

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.     

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。     

青藏高原多年冻土区高寒植被物种多样性和地上生物量

基于样方调查统计了青藏高原多年冻土区高寒草地生态系统植物的科属组成,计算了多样性指数和均匀度指数,探讨了多年冻土退化对高寒草地物种多样性的影响。结果表明:多年冻土退化过程中物种组成在属和物种丰富度上呈现降低趋势,湿、中生植物逐渐被旱中生和旱生植物替代;青藏高原多年冻土退化会导致高寒草地生态系统的物种多样性和初级生产力的降低,影响高寒草地生态系统的稳定性;物种多样性与初级生产力具有密切的抛物线型关系。     

青藏高原冻土区土壤垂直剖面中微生物的分布与多样性

【目的】冻土区储存着大量的有机碳,全球气候的变化导致冻土不断融解退化,土壤微生物对冻土有机碳的分解作用在一定程度上将会加重全球温室效应。在研究中,为了解冻土区土壤微生物的分布与多样性,对青藏高原冻土区垂直剖面中的微生物组成进行研究。【方法】采用分子生物学方法,对剖面土壤样品中的古菌与细菌的16S r RNA基因和真菌的ITS序列进行PCR扩增,并分别构建其基因文库,通过序列的同源性比较进行系统发育学分析和多样性指数分析。【结果】垂直剖面土壤中古菌序列分别属于泉古菌(Crenarchaeota)和广古菌(Euryarchaeota)两个门,它们分别占克隆序列总数的29.0%和71.0%;其中泉古菌门只包括Group1.3b/MCG-A这一种类型,在古菌序列中所占的比例为29.0%,广古菌门包括4种类型,其中Methanomicrobiales序列在古菌克隆文库中所占比例较高(52.0%);分层位看,冻土活动层古菌优势类群包括Group1.3b/MCG-A、Methanomicrobiales和Methanosaetaceae,过渡层的优势类群包括Group1.3b/MCG-A和Methanomicrobiales两类,而古菌在冻土层的优势类群只有Methanomicrobiales这一种类型。细菌序列分属于10个类群,其中放线菌(Actinobacteria)、厚壁菌(Firmicutes)与变形菌(Proteobacteria)为剖面主要的优势类群,分别占克隆序列总数的28.9%、16.9%和12.1%;在冻土活动层,细菌的优势类群为Proteobacteria和Firmicutes,而在冻土过渡层与冻土层,细菌优势类群仅包括Actinobacteria一种类型。所有真菌序列均属于子囊菌门(Ascomycota)和担子菌门(Basidiomycota),分别占克隆序列总数的75.3%和24.7%;子囊菌以Cladosporium sp.和Pseudeurotium bakeri为主要的优势类群,担子菌以Dioszegia sp.为主要的优势类群,所占比例分别为35.5%、34.4%和22.6%;真菌在冻土活动层的优势类群只包括Pseudeurotium bakeri这一种类型,而在冻土过渡层与冻土层,真菌优势类群则包括Dioszegia sp.和Cladosporium sp.两类。【结论】该剖面在垂直剖面上古菌、细菌与真菌多样性较高,冻土活动层与冻土层之间群落组成差异明显。     

青藏高原地区山生柳遗传多样性研究

利用叶绿体非编码区片段研究分布于青藏高原地区的山生柳居群遗传多样性,对未来山生柳生态环境和青藏高原地区物种丰富度的保护具有指导意义。该研究设计并筛选出cpDNA引物5'trnG2G-3'trnG(UUC)和5'rpS12-rpL20,用扩增出的片段和对应的联合片段进行后续的遗传多样性分析。结果表明:通过山生柳的联合片段检测到35种单倍型,单倍型多态性0.626,核苷酸多态性0.000 85。中性检验Tajima’s D(-2.286 70,P0.01)和Fu’s Fs(-5.298 05,P0.02)都是显著负值,推测山生柳个体数近期经历过扩张。AMOVA分析显示,居群内和居群间遗传变异分别为93.70%和6.30%,表明居群内的变异是山生柳遗传变异的主要来源。居群间遗传分化程度中等偏低(FST=0.063),基因流(N_m)为7.439,说明山生柳各居群的基因交流非常频繁,不同地理居群间存在一定的基因流动。遗传分化系数N_(ST)(0.075)大于GST(0.068)和基于遗传距离和单倍型的UPGMA聚类分析,表明山生柳12个居群分为4组且与居群的地理分布没有明显相关性。山生柳是进行有性繁殖还是无性繁殖主要受环境因素的影响,居群内变异是山生柳遗传变异性的主要来源,居群间基因交流频繁。     

青藏高原常见雀形目鸟类的筑巢特征

于1990—2004年的繁殖季节,在青藏高原北部地区收集了12种常见的雀形目鸟类的巢,并且对这些鸟巢的分布格局和结构特征进行了比较研究。所有鸟巢分布表现出草地、灌木丛和沼泽的水平分割和地上、地面及地下的垂直分割的空间分布模式,其中地面杯状巢最普遍。巢结构特征,存在从简单到复杂的系列谱变化,主要表现:巢形状从浅到深,从开放到封闭;巢材性质从单一的植物性到复合的动植物性;巢材重从少到多。不管这些变化有多大,都反映了所有鸟种选择巢址是在安全和隔热两种基本条件之间权衡。在变化谱上的每种鸟巢都有自己的利弊,选择哪种类型的巢是由鸟本身的遗传和环境特征两方面的因素决定的。另外,巢材的运输反映了亲鸟对筑巢活动的投资,是繁殖投入的重要组成部分。因此,巢材重与亲鸟体重之比可以反映出筑巢活动投资的高低。百灵科鸟的开放式地面巢材重大约是亲鸟体重的1/2;而褐背拟地鸦的地下封闭巢的巢材重约为亲鸟体重的5倍以上。其余种类都在两者之间变化。总之,如此不同的投资差异是在捕食压力和种间竞争作用下以及亲鸟为满足鸟卵胚胎和雏鸟迅速生长发育的必要条件下,各种生物学特征协调的结果。     

青藏高原极端生境细菌多样性差异及影响因素

土壤微生物组对于生态系统的可持续性至关重要,青藏高原独特的地理环境孕育了多样的极端环境,其土壤细菌组成差异及其驱动因素尚不清楚。【目的】探究不同极端生境土壤细菌多样性及其影响因素。【方法】对7种典型的青藏高原极端生境土壤DNA进行16SrRNA基因高通量测序,通过生物信息分析,找出不同生境细菌群落组成、功能差异;结合土壤理化因子,进一步分析细菌组成差异的潜在影响因素。【结果】通过高通量测序,从7个不同生境的36个土壤样品中共获得16 323 712高质量reads,26 504个可操作分类单元(operational taxonomic units, OTUs)。在门分类水平上,各生境中注释到的放线菌门(Actinomycetota)与假单胞菌门(Pseudomonadota)相对丰度均最高;在属分类水平上,芽孢杆菌属(Bacillus)、Ambiguous＿taxa、土壤红杆菌属(Solirubrobacter)、假节杆菌属(Pseudarthrobacter)等为优势属。另外,不同生境中的细菌α多样性无显著差异,但是β多样性差异显著,并且通过LEfSe分析进一步说明了不同生境细菌群...     

Genetic diversity and population structure of Swertia tetraptera (Gentianaceae), an endemic species of Qinghai-Tibetan Plateau

Swertia tetraptera Maxim is an annual alpine herb endemic to the Qinghai-Tibetan Plateau (QTP). Its populations are locally scattered as isolated patches throughout this region. Genetic variation within and among thirty-four populations of this species was assessed using ISSR fingerprinting with 10 primers. High levels of genetic diversity exist within species (P = 98.9%, I = 0.3475; He = 0.2227), while the within-population diversity is low (P = 32.7%, I = 0.177; He = 0.12). High levels of genetic differentiation were detected among populations based on various statistics, including Nei’s genetic diversity analysis (G_ST = 0.4608), Bayesian analysis (θ^B = 0.476) and AMOVA (F_ST = 0.57). That is, populations shared low levels of genetic identity (I = 0.2622–0.0966). This genetic structure was probably due to severe genetic drift, breeding system and limited gene flow. The observed genetic structure of the populations implies that different populations across the distribution range of the species should be sampled to maintain high genetic diversity when a conservation strategy is implemented.     

青藏高原地区不同环境条件下鳞翅目昆虫物种多样性与系统发育多样性的初步研究

本研究以青藏高原鳞翅目蛾类为例,探究不同环境梯度下蛾类群落物种多样性及系统发育多样性,并探讨物种多样性与系统发育多样性、不同的环境因子与蛾类系统发育多样性之间的关系。结果表明:(1)波密的物种多样性和系统发育多样性程度最高;(2)系统发育多样性与物种多样性指数之间存在正相关关系,相关性排序为:物种丰富度(R=0.9740,P=4.30E-05)香农指数(R=0.8323,P=0.0103)Invsimpson指数(R=0.8061,P=0.0156)辛普森指数(R=0.6311,P=0.0933);(3)在21个环境因子中,有4个环境因子与系统发育多样性之间呈现显著相关,分别是最湿润季度的降水量、最热季度的降水量、最湿润月份的降水量和最湿润季度的平均气温,它们可能是影响青藏高原地区蛾类系统发育多样性的关键生态因子。     

青藏高原濒危植物唐古特大黄的遗传多样性

唐古特大黄(Rheum tanguticum)是中国传统的中藏药材,近几年由于生境的严重破坏,已濒临灭绝,并被列入濒危植物名单。为了探索唐古特大黄物种濒危的原因并保护其野生资源,本研究采集了9个居群87个个体的唐古特大黄样本,基于该物种的叶绿体基因trn S-G序列对其进行了遗传多样性研究。结果表明,唐古特大黄物种具有较高的遗传多样性水平(Ht=0.694),其中95.97%的遗传分化来自于居群间(G_(ST)=0.960),4.03%的遗传分化来自于居群内(Hs=0.028)。AMOVA分析也显示唐古特大黄居群间基因流较小(N_m=0.01),存在较高的遗传分化(F_(ST)=0.9631)。唐古特大黄较高的遗传多样性水平可能与该物种较长的进化史和生活史有关,居群间较高的遗传分化可能与高山地区特殊的地理环境和人类活动有关。根据研究结果,建议对唐古特大黄所有野生居群进行就地保护,同时收集种质资源开展异地繁殖工作,以保护物种的遗传多样性,维持其进化潜力。     

Lead accumulation in the aquatic fern Azolla filiculoides.

In this study, we characterized lead (Pb2+) accumulation and storage by the aquatic fern Azolla filiculoides. Lead precipitates were detected in the vacuoles of mesophyll cells of Azolla plants cultured for 6 d in rich growth medium containing 20 mg l(-1) Pb2+. Energy dispersive spectroscopy (EDS) analysis of the relative element content of leaves collected from these plants revealed a 100% increase in the levels of P, S, Na and Ca and a 40% decrease in Mg and Cl compared to the untreated plants. Both Azolla whole plants and isolated apoplasts were incubated for 6 d in 20 mg l(-1) Pb2+. Lead content in the whole plant composed 0.37%, 2.3% and 1.8% of the dry weight after 2, 4 and 6 d of growth, respectively, while the isolated Azolla apoplast contained 0.125%, 1.22% and 1.4% Pb2+, respectively. Lead content in Azolla whole plant increase by 200%, 100% and 22% after 2, 4 and 6 d of growth, respectively, when compared to Azolla apoplast. Dark, electron dense deposits of lead were observed in light and transmission electron microscope in leaf cells treated with lead. All the observed lead deposits were localized in vacuoles while larger lead deposits were found in mature leaves than in young leaves. No lead deposits were found in cells of the cyanobiont Anabaena when the plants were exposed to similar conditions. Activity and content of V-H+-ATPase were studied in Azolla plants grown in the presence of 20, 40 and 80 mg l(-1) of lead for a period of 4 d. Activity of V-H+-ATPase was increased by 190%, 210% and 220%, respectively, but the content of V-H+-ATPase was reduced by all lead concentrations.     

Global patterns of fern species diversity: An evaluation of fern data in GBIF

Despite that several studies have shown that data derived from species lists generated from distribution occurrence records in the Global Biodiversity Information Facility (GBIF) are not appropriate for those ecological and biogeographic studies that require high sampling completeness, because species lists derived from GBIF are generally very incomplete, Suissa et al. (2021) generated fern species lists based on data with GBIF for 100 km × 100 km grid cells across the world, and used the data to determine fern diversity hotspots and species richness–climate relationships. We conduct an evaluation on the completeness of fern species lists derived from GBIF at the grid–cell scale and at a larger spatial scale, and determine whether fern data derived from GBIF are appropriate for studies on the relations of species composition and richness with climatic variables. We show that species sampling completeness of GBIF is low (<40%) for most of the grid cells examined, and such low sampling completeness can substantially bias the investigation of geographic and ecological patterns of species diversity and the identification of diversity hotspots. We conclude that fern species lists derived from GBIF are generally very incomplete across a wide range of spatial scales, and are not appropriate for studies that require data derived from species lists in high completeness. We present a map showing global patterns of fern species diversity based on complete or nearly complete regional fern species lists.     

青藏高原高寒草甸生态系统的恢复能力

近年来,青藏高原高寒草甸生态系统呈现退化的趋势.本文利用中国科学院海北高寒草甸生态系统定位站多年观测的长时间序列数据,采用定量方法度量高寒草甸自然生态系统的恢复能力,评估该系统的持久性,并结合系统现状提出避免系统崩溃的对策.结果表明,高寒草甸净初级生产力的动态行为以对降水和气温的即时直接响应为主.无论是净初级生产力对自身的"记忆"程度,还是主要气候因子对初级生产力的"滞后"作用,均比较微弱,说明高寒草甸生态系统有较强的恢复能力,即有较强的持久能力.与世界其他地区草地生态系统恢复能力度量结果相比较,高寒草甸生态系统显示较强的恢复能力.科学地利用高寒草地资源,积极恢复治理退化草地,是维持脆弱的高寒草甸生态系统持久的关键.     

Intra-population genetic diversity of two wheatgrass species along altitude gradients on the Qinghai-Tibetan Plateau: its implication for conservation and utilization

A fluorescence-based AFLP fingerprinting was applied to investigate genetic diversity in 22 natural populations of two wheatgrasses from Qinghai-Tibetan Plateau at different altitudes: the hexaploid Elymus nutans Griseb and the tetraploid E. burchan-buddae (Nevski) Tzvelev (Poaceae). Five selective primer combinations used in this study generated a total of 637 AFLP fragments across all the samples, with 612 fragments in E. nutans and 570 in E. burchan-buddae. About 45% of the scored fragments were <200 bp and about 13% of the fragments were >400 bp. Results showed that genetic diversity within populations of the two Elymus species increased gradually with the increase in altitudes from the lowest sampling sites (2800 m) and reached a plateau at the medium altitudes, and then started to decrease with the increase in altitudes. Regression analysis demonstrated a clear pattern between the expected heterozygosity (H _e) or Shannon index (I) and altitude variation, where the highest H _e values (0.3449 for E. nutans and 0.3167 E. burchan-buddae) and I values (0.5123 and 0.4759) were expected at the altitudes 3399 m and 3418 m across all sampling sites, respectively for E. nutans and E. burchan-buddae. In other words, higher genetic diversity was observed in populations occurring at the medium altitudes (3200–3600 m) than those at the low and high altitudes for the two Elymus species. Principal coordinate analysis (PCA) did not show clear association between genetic relationships of populations and their occurrences at a particular altitude. The above results suggest that efforts for conservation and utilization of two wheatgrasses species should focus more on populations occurring at the medium altitudes.     

Reduction in leaf size at higher altitudes across 39 broad-leaved herbaceous species on the northeastern Qinghai-Tibetan Plateau

青藏高原东北部39种阔叶草本植物叶大小随海拔增加而减少种间或种内的叶大小随环境变化存在很大的差异,但这些差异如何随海拔变化一直都在争论。我们在青藏高原东北缘的冷龙岭和达坂山,沿海拔3200–4400 m的山坡上选取生长在开阔环境下的39种阔叶草本植物,观测了叶大小、叶长、叶宽和比叶重。研究结果表明,随海拔增加叶片显著减小,而且叶片面积的减小主要受叶片长度的影响,即随海拔增加叶长度减小明显。此外,叶片面积与海拔之间的关系随物种、叶倾角和叶表面特征而不同。利用局地环境观测数据驱动的能量平衡模型分析发现：叶温能更密切地追随气温变化,叶大小变化对叶温的影响在高海拔更为强烈。同时,基于上述能量平衡的计算结果,我们认为青藏高原东北部阔叶草本植物的海拔分布上限大约为5400 m。     

青藏高原草地生态系统服务功能的季节动态变化

根据生态系统服务功能理论,利用RS和GIS技术,以生长季为时间单元,对青藏高原研究区草地生态系统服务功能的动态过程进行有效分析和评价.结果表明:提供生物量功能呈现上升—下降—上升的过程,在5月和9月分别出现两个高峰值,其中5月为最高峰值.影响该功能的主要因子为光合有效辐射值、水分状况和地下生物量的季节变化;碳蓄积和氧释放功能呈现上升—下降—上升的弱“N”型趋势;土壤养分保持功能也呈弱“N”型趋势,并在5月份出现最高值;草地保持土壤水分的功能在生长季内呈较强的阶段性变化,这主要与草地植物生长的季节性耗水变化规律有关.