陕北黄土高原植被生态系统水分利用效率气候时滞效应

基于月尺度气温、降水以及MODIS-GPP、MODIS-ET遥感数据,采用基于像元的时滞偏相关分析,揭示了陕北黄土高原植被生态系统水分利用效率气候时滞效应及其影响因素。结果表明:①2000—2014年,受退耕还林草生态工程和气候变化的双重影响,陕北黄土高原WUE呈波动变化趋势,2001—2003年显著下降,2003—2005年、2010—2013年显著上升。受不同植被类型的影响,年内WUE呈急速双峰、缓速双峰和单峰型3种变化状态。②陕北黄土高原WUE对降水存在明显的时滞效应,滞后时间多为3个月,人为扰动较大的I-1、I-2、Ⅱ-2生态区以及植被覆盖度较高的Ⅲ-3生态区WUE对降水的时滞响应程度明显低于其他生态区;而对气温的时滞效应较弱,仅南部的Ⅲ-2、Ⅲ-3生态区WUE对气温存在1—2个月滞后时间。③不同植被类型WUE对降水的时滞效应较明显,荒漠类植被WUE对降水时滞响应程度最强,滞后时间近3个月,针叶林时滞响应程度最弱,滞后时间为2.1个月;但对气温的时滞效应总体较弱,针叶林WUE对气温滞后时间为15 d,其余大多数植被类型WUE对气温不存在滞后时间。④WUE气候时滞效应对植被覆盖度的敏感性存在一定的阈值效应,植被覆盖度高于阈值62.3%时,对降水的时滞效应开始逐渐减弱,而对气温的时滞效应逐渐显现。     

“Into and Out of” the Qinghai‐Tibet Plateau and the Himalayas: Centers of origin and diversification across five clades of Eurasian montane and alpine passerine birds

Encompassing some of the major hotspots of biodiversity on Earth, large mountain systems have long held the attention of evolutionary biologists. The region of the Qinghai‐Tibet Plateau (QTP) is considered a biogeographic source for multiple colonization events into adjacent areas including the northern Palearctic. The faunal exchange between the QTP and adjacent regions could thus represent a one‐way street (“out of” the QTP). However, immigration into the QTP region has so far received only little attention, despite its potential to shape faunal and floral communities of the QTP. In this study, we investigated centers of origin and dispersal routes between the QTP, its forested margins and adjacent regions for five clades of alpine and montane birds of the passerine superfamily Passeroidea. We performed an ancestral area reconstruction using BioGeoBEARS and inferred a time‐calibrated backbone phylogeny for 279 taxa of Passeroidea. The oldest endemic species of the QTP was dated to the early Miocene (ca. 20 Ma). Several additional QTP endemics evolved in the mid to late Miocene (12–7 Ma). The inferred centers of origin and diversification for some of our target clades matched the “out of Tibet hypothesis’ or the “out of Himalayas hypothesis” for others they matched the “into Tibet hypothesis.” Three radiations included multiple independent Pleistocene colonization events to regions as distant as the Western Palearctic and the Nearctic. We conclude that faunal exchange between the QTP and adjacent regions was bidirectional through time, and the QTP region has thus harbored both centers of diversification and centers of immigration.     

Examining differences in phylogenetic composition enhances understanding of the phylogenetic structure of the shrub community in the northeastern Qinghai‐Tibetan Plateau

Periodic climatic oscillations and species dispersal during the postglacial period are two important causes of plant assemblage and distribution on the Qinghai‐Tibet Plateau (QTP). To improve our understanding of the bio‐geological histories of shrub communities on the QTP, we tested two hypotheses. First, the intensity of climatic oscillations played a filtering role during community structuring. Second, species dispersal during the postglacial period contributed to the recovery of species and phylogenetic diversity and the emergence of phylogenetic overdispersion. To test these hypotheses, we investigated and compared the shrub communities in the alpine and desert habitats of the northeastern QTP. Notably, we observed higher levels of species and phylogenetic diversity in the alpine habitat than in the desert habitat, leading to phylogenetic overdispersion in the alpine shrub communities versus phylogenetic clustering in the desert shrub communities. This phylogenetic overdispersion increased with greater climate anomalies. These results suggest that (a) although climate anomalies strongly affect shrub communities, these phenomena do not act as a filter for shrub community structuring, and (b) species dispersal increases phylogenetic diversity and overdispersion in a community. Moreover, our investigation of the phylogenetic community composition revealed a larger number of plant clades in the alpine shrub communities than in the desert shrub communities, which provided insights into plant clade‐level differences in the phylogenetic structures of alpine and desert shrub communities in the northeastern QTP.     

黄土高原地区生态系统碳储量空间分布及其影响因素

准确估算生态系统碳储量,探明其空间分布及其影响因素对区域生态管理具有重要意义,但黄土高原地区碳储量现状、空间格局及其驱动因素尚不清楚。选择黄土高原地区森林（包括乔木林和灌木林）,草地和农田生态系统为对象,基于大量实测样点通过克里金插值和地统计方法,评估了三种生态系统地上生物量碳密度、地下生物量碳密度和0-100 cm土壤有机碳密度空间分布,并通过路径分析探讨了各碳库的主要影响因素。结果表明：黄土高原地区约占全国总面积的6.7%,其生态系统总碳储量约为2.29 Pg,仅占我国生态系统碳储量的2.3%。生态系统各碳库中,地上生物量碳储量、地下生物量碳储量、土壤有机碳储量分别为0.44、0.32和1.52 Pg;森林、草地、农田（仅指土壤）生态系统碳储量分别为0.98、1.09和0.21 Pg。气候（年均温度、年均降水）、海拔、坡度、土壤质地（砂粒、粉粒、粘粒含量）、植被覆盖状况（用NDVI表示）等因子可解释地上生物量碳密度、地下生物量碳密度、农田土壤有机碳密度空间变异的12%、8%和32%,其中,年均降水、海拔、粘粒含量是黄土高原地区生态系统碳储量空间格局的主要影响因素。本研究表明,由于黄土高原地区独特的气候、地形和土壤条件,其生态系统虽然具有较大的碳储量,但是低于我国生态系统碳储量的平均水平。     

基于多源数据的黄土高原陆地水循环结构变化分析

近几十年间,黄土高原的水循环进程在人类活动与气候变化的影响下已产生了剧烈的变化。为加深对水循环结构变化的了解与认识,利用1982-2010年的降水、蒸散发、径流、土壤储水量和社会经济用水等数据,运用Mann-Kendall趋势检验和线性回归分析方法,对黄土高原的水量平衡进行评估,且细化了组成水循环的12种水文变量,并分析了水循环各分量的变化趋势及其结构的演化规律。由于网格化的社会经济用水数据（1982-2010年）对本研究产生了较大的时间限制,因此本文注重于探究这29年间黄土高原各水文变量的变化趋势及水循环结构的演化规律。结果表明：在自然系统中,蒸散发以1.97 mm/a的速率上升（P<0.01）,径流、降水和土壤储水量分别以1.01 mm/a（P<0.01）、0.77 mm/a和0.46 mm/a的速率下降。在社会系统中,社会经济用水以0.50 mm/a的速率上升,其中主要由于生活、制造业、发电和采矿用水分别以0.22、0.23、0.30 mm/a和0.01 mm/a的速率增加所导致。此外,灌溉和牲畜用水分别以0.25 mm/a（P<0.05）、0.01 mm/a（P<0.01）的速率减少。就水循环结构而言,多年平均蒸散发和社会经济用水占水循环的平均比例分别为80.95%、15.27%,并以每年0.16%、0.06%的速率逐渐升高。径流、土壤储水量的变化占水循环的平均比例分别为4.00%、-0.24%,并以每年0.24%（P<0.01）、0.02%的速率逐渐下降。随着社会经济的发展和人口的增加,区域水资源供需矛盾将进一步加剧,本研究对黄土高原水资源的科学调控与可持续利用有重要参考意义。     

不同耕作方式对旱地全膜双垄沟播玉米产量和水分利用的影响

为明确新型耕作技术--立式深旋耕作对西北黄土高原半干旱区土壤水分含量、玉米产量和水分利用效率的影响,采用随机区组设计,于2016和2017年设置立式深旋耕作40 cm （VRT）、深松40 cm （SS）、旋耕15 cm （TT）和免耕（ZT）4种耕作方式,测定0-300 cm土层土壤含水量、地上生物量、叶面积指数（LAI）和SPAD、产量等指标,计算阶段耗水量、水分利用效率（WUE）等。结果表明,VRT在2017年播前0-40 cm土层的土壤贮水量分别较SS、TT、ZT增加了7.7、8.6、6.6 mm,在0-100 cm土层增加了18.2、22.8、20.2 mm,均达到显著差异。VRT显著促进干旱年的花前耗水和平水年的花后耗水,提高玉米地上生物量、LAI和SPAD,其中地上生物量较SS、TT、ZT分别增加了14.7%-18.3%、12.7%-18.8%和22.8%-29.1%。基于较为优势的植株生长,VRT籽粒产量较SS、TT和ZT分别增加了12.0%-13.0%、13.7%-33.6%、24.0%-47.4%。因此,虽然VRT提高了玉米耗水,并与ZT达到显著差异水平,导致收获后土壤贮水量低于其他三种耕作方式,但2017年播前0-100 cm土层土壤贮水量显著高于其他3种耕作处理;尽管0-300 cm土层土壤贮水量较SS、TT和ZT下降了11.4、14.8、20.5 mm,但它们之间无显著差异。以上结果表明,VRT能够同时促进玉米耗水和降水入渗,维持土壤水分平衡,是一种有效的抗旱增墒耕作方法,可在半干旱区玉米生产中推广应用。     

西藏色季拉山垂直植被带土壤细菌群落组成及功能潜势

研究青藏高原土壤微生物群落组成和功能的空间分布特征有助于深入理解典型高寒生态系统中土壤微生物的重要生态功能。本研究采用16S rDNA高通量测序方法,分析了西藏色季拉山4个不同海拔土壤细菌群落物种组成和功能潜势的变化特征及其驱动因子。结果表明: 随着海拔的升高,土壤细菌的丰富度和Shannon多样性指数显著降低;酸杆菌门、绿弯菌门、芽单胞菌门和硝化螺旋菌门的相对丰度显著增加,而变形菌门、放线菌门和拟杆菌门的相对丰度则显著降低。KEGG二级代谢通路中,膜运输及氨基酸、脂类、萜类和聚酮类化合物代谢相关基因的相对丰度在高海拔显著降低,而碳水化合物代谢、信号转导、复制与修复、酶家族等基因丰度则显著升高。不同海拔土壤细菌群落组成和功能潜势的变化受到植被和土壤因子的显著影响,并且pH值是关键驱动因子。群落功能潜势与放线菌门、拟杆菌门、纤维杆菌门等种群丰度显著相关。不同海拔下群落KEGG代谢通路基因组成的差异(β多样性)与土壤细菌群落结构的差异呈显著正相关,说明微生物群落组成与功能潜势之间可能存在紧密关联。     

Diversity of Culturable Bacteria Isolated from Highland Barley Cultivation Soil in Qamdo,Tibet Autonomous Region

The soil bacterial communities have been widely investigated. However, there has been little study of the bacteria in Qinghai-Tibet Plateau, especially about the culturable bacteria in highland barley cultivation soil. Here, a total of 830 individual strains were obtained at 4°C and 25°C from a highland barley cultivation soil in Qamdo, Tibet Autonomous Region, using fifteen kinds of media. Seventy-seven species were obtained, which belonged to 42 genera and four phyla; the predominant phylum was Actinobacteria (68.82%), followed by Proteobacteria (15.59%), Firmicutes (14.29%), and Bacteroidetes (1.30%). The predominant genus was Streptomyces (22.08%, 17 species), followed by Bacillus (6.49%, five species), Micromonospora (5.19%, four species), Microbacterium (5.19%, four species), and Kribbella (3.90%, three species). The most diverse isolates belonged to a high G+C Gram-positive group; in particular, the Streptomyces genus is a dominant genus in the high G+C Gram-positive group. There were 62 species and 33 genera bacteria isolated at 25°C (80.52%), 23 species, and 18 genera bacteria isolated at 4°C (29.87%). Meanwhile, only eight species and six genera bacteria could be isolated at 25°C and 4°C. Of the 77 species, six isolates related to six genera might be novel taxa. The results showed abundant bacterial species diversity in the soil sample from the Qamdo, Tibet Autonomous Region.     

青藏高原湿地植物轻金属元素含量特征及其与环境因素的关系研究

以青藏高原湿地植物为研究对象,通过对青藏高原35个采样点的野外调查采样,对青藏高原湿地植物8种轻金属元素(Al、Mg、Ca、Sr、Ba、K、Na、Li)含量的特征及其与环境因素的关系进行分析。结果显示,不同湿地植物对不同轻金属元素的富集能力存在差异。轻金属元素在湿地植物体内的平均含量依次排序为:Li相似文献   

金露梅与格桑花

青藏高原的格桑花是什么植物或者说是什么植物的花,存在广泛争议,困扰着想一探究竟的人们。格桑花作为一种精神存在于藏族百姓心中,是他们追求幸福吉祥和美好生活的情感象征,是重要的雪域文化标识,认识熟知并开发利用好它,将有助于推动藏区生态、文化和产业振兴。金露梅是青藏高原分布最广的树木,按集生羽状复叶小叶数可分为5叶金露梅和7叶金露梅,《中国植物志》对它们的记载分别是金露梅（Potentilla fruticosa L.）和小叶金露梅（P.parvifolia Fisch.）。通过对青藏高原植被和历史文化景观考察,结合当地藏民描述及地方传说,本研究认为格桑花就是金露梅,其分布海拔可以拓展到5200 m的高寒恶劣环境。金露梅生性强健,耐寒、耐旱、耐瘠薄、耐强光,象征着藏族同胞刚毅、坚强、勤劳质朴、不畏严寒、生命力顽强的品格。