岩溶山区和石漠化区表土孢粉组合的差异性--以重庆市南川区为例

通过对重庆市南川区岩溶山区和石漠化区14个不同植被类型的表土调查和采样,以研究该区表土孢粉组合特征的差异性。结果显示:(1)岩溶山区的表土孢粉组合中以乔木花粉为优势,含量为34.38%-63.39%,其次是草本和蕨类植物的孢粉,含量为32.04%-58.18%,灌木花粉含量最小,为6.08%-29.77%,沼生草本也有少量,仅为0.14%,这与当地的现代植被基本相同;(2) 石漠化地区的表土孢粉组合以草本和蕨类植物孢粉占优势,含量为46.40%-76.47%,其次是乔木花粉(主要为马尾松),含量为17.73%-46.84%,灌木花粉含量最小,为5.79%-12.50%,说明其植被退化严重;(3)石漠化区的表土孢粉组合中有很多喜钙性、旱生性、石生性植物,对生态恢复和重建有很好的指示意义,为该区恢复和重建自然生态环境提供参考性依据。     

重庆金佛山国家自然保护区现代植被表土孢粉的初步研究

通过对重庆金佛山国家自然保护区10个不同植被类型的表土调查和采样,研究该区表土孢粉组合特征.结果表明,研究区植物孢粉共由106科属组成,其中以针叶乔木、蕨类和阔叶乔木孢粉占优势,含量分别为8.94%-56.30%、19.73%-46.77%和6.17%-39.28%,其次是灌木和草本花粉,分别为6.24%-29.77%...     

重庆喀斯特地区现代花粉组合与植被的关系

重庆喀斯特地区4种不同地貌单元的81份表土和苔藓样品的孢粉分析结果表明:(1)研究区植物孢粉组合共由109科属组成。除金佛山外,其他植被退化严重地区样点均以草本和蕨类植物占据优势(剔除石漠化治理大量引种的马尾松、柳杉和侧柏等乔木花粉),其次是乔木植物花粉(主要为马尾松),灌木植物花粉含量很低,显示该区植被退化严重;(2)孢粉组合的PCA分析能够很好地将研究区的现代孢粉组合区分开来,较好地反映了重庆喀斯特地区不同地貌单元的植被特征,特别是石漠化区植被退化严重的孢粉组合特征。生态保护较好、自然植被发育的金佛山地区具有106科属的乔木、灌木与草本孢粉类型,以及高含量的乔木花粉,而喀斯特石漠化地区的鸡公山(46科属)、青木关镇(56科属)和南平镇(50科属)则表现为乔灌木孢粉类型较少;(3)银杉作为金佛山特有的孑遗植物,其花粉含量明显低于松属花粉,说明其花粉不利于远距离传播;(4)随着土地利用强度的增加,现代孢粉组合中乔灌木花粉含量和种类越少,草本和蕨类植物孢粉含量越多,且以耕地杂草为主。因此,土地利用方式的变化是喀斯特石漠化区次生植被及其现代孢粉组合变化的主要影响因素。研究可为重庆喀斯特地区土地利用策略的制定,重庆及其周边地区第四纪古植被、古气候和古环境重建研究,以及中国孢粉数据库建设提供基本数据和科学依据。     

云南泸沽湖及周边山地表层孢粉与植被关系研究

本文对云南泸沽湖周边山地不同植被类型下采集的32个表土样品和36个泸沽湖湖泊表层样品进行了孢粉分析,探讨了不同植被类型内的表土孢粉散布特征,对比分析了山地表土与湖泊表层孢粉分布特征的差异。结果表明,不同山地植被类型的孢粉组合具有不同的代表性成分与变化特征,能够较好地反映相应的植被类型。湖泊表层孢粉研究表明,湖泊内不同位置的孢粉组合差异较小,说明湖泊表层孢粉反映的是区域植被的平均分布状况。对比分析泸沽湖周边山地表土与湖泊表层样品的孢粉组合,两者存在一定的差异,表现为:湖泊表层的孢粉组合中乔木花粉(主要是松属)平均含量比表土高,但波动范围要小;草本花粉平均含量要低,且波动范围也小。这可能是由于乔木植物植株较高,而且有些乔木植物花粉具有气囊,更易借助风力将花粉传播到比较远的湖泊中的原因造成的。冷杉和铁杉花粉在所有样品中含量都相对较低,分别不高于6.5%和3.6%;桦属、桤木属、常绿栎类花粉的最高值出现在有这些母体植物生长的表土样品中,在其他样品中则明显较低。在表土孢粉样品中经常可以见到冷杉的气孔器,但在湖泊表层样品中却没有见到,说明气孔器不易到达湖泊中。该研究是对中国西南表层孢粉研究的有益补充,同时为泸沽湖新生代特别是第四纪化石孢粉解释提供了可靠的参考和依据。     

北疆表土花粉组合及其与植被和气候的关系

通过对比分析北疆荒漠草原区和典型草原区表土和牛粪样品中的孢粉组合,发现这两类样品的孢粉组合大体相近,其乔木花粉百分比大都低于10%,灌木花粉平均为5.6%,草本花粉大都高于70%,并以藜科(Chenopodiaceae)、蒿属(Artemisia)为最主要的花粉类型。牛粪中孢粉种类低于表土,且乔木花粉含量(2.04%)亦低于表土(3.78%)。表土形成的时间存在一定的不确定性,而牛粪为现代样品,牛粪的孢粉组成可能会更好地指示现代植被组成,因而牛粪样品可以在北疆荒漠草原、典型草原地区作为一种新的现代孢粉研究材料。从荒漠草原到典型草原,表土中乔木花粉百分比增多,灌木和草本下降;而牛粪中则相反,乔木花粉百分比下降,灌木和草本的比例上升,这可能与牛以草本植物为主要食物有关。表土和牛粪样品中主要种属(蔷薇科、禾本科、伞形科、豆科等)与环境因子的主成分分析显示,孢粉组合与多年平均6—8月降水量和年均降水量的相关性最显著,其次为最冷月平均温度和最热月平均温度,而与年均温相关性较低。该研究结果指示,降水可能是影响北疆现代植被空间分布的最主要因素。     

新疆阿尔泰红山嘴地区的表土孢粉与现代植被

在新疆阿尔泰山中段的红山嘴地区选取一条沿海拔745-2 413 m的不同植被带群落样方进行调查, 对应采集37个表土样品进行孢粉统计和排序分析, 初步探究了红山嘴地区的植被与表土孢粉之间的对应关系, 并将之与新疆阿尔泰西部的喀纳斯西坡孢粉垂直带进行对比。结果表明, 红山嘴地区表土孢粉谱依照海拔高度自上而下划分为4个孢粉组合类型, 分别对应亚高山草甸、山地森林、灌丛草原和荒漠草原。乔木植物中云杉属(Picea)和松属(Pinus)花粉, 灌木植物中麻黄属(Ephedra)及草本植物中的苋科和蒿属(Artemisia)因受到自然风力、水流及人为活动的影响, 表现出明显的超代表性; 乔木植物中的落叶松属(Larix)花粉, 草本植物中的禾本科及莎草科花粉, 却在其自身为优势种的群落中呈现低代表性; 蒿属与苋科花粉百分含量的比值(Ar/Am)能较好地反映该区气候垂直带的干湿状况, 灌丛草原带的Ar/Am低, 在一定程度上反映了人类活动对草原灌丛化的影响。与新疆阿尔泰西部的喀纳斯西坡孢粉垂直带相比, 红山嘴垂直带的孢粉类型偏少, 同时相似的孢粉带在该区的分布高度比喀纳斯西坡高。此外, 排序分析(RDA)结果表明, 年降水量是影响该区表土孢粉组合的主要环境因子。     

云南亚热带南部表土孢粉组合与植被间的定量关系

以云南亚热带南部沿温度带分布的35个表土孢粉样品和7个植被样方调查为基础,计算了代表性孢粉类型的百分比和孢粉浓度,及常见孢粉的R值,并分析了影响R值的因素;同时,研究了植物群落和样方内孢粉组合的相似度。结果表明,云南亚热带南部表土样品孢粉产量丰富,蕨类植物孢子产量较高,具有典型的亚热带特征,且山地垂直分异显著;木本、草本植物花粉基本代表了区域内乔木和草本植物特征,蕨类植物孢子则具有超代表性;表土孢粉组合与植物群落间的相似系数绝大部分都在70％以上,表土孢粉组合基本上可以反映植物群落面貌;表明云南亚热带地区表土孢粉与现代植被之间具有较好的对应关系,这对在该区利用化石孢粉资料定量恢复古植被和重建古气候有重要意义。     

东北长白山垂直林带下现代表土花粉与植被关系

在长白山北坡5个垂直植被带的林下采集29个表土(苔藓)样品进行孢粉分析，同时将其结果作对应分析。结果表明，除个别样品，在长白山垂直植被带的孢粉组合中乔木花粉占优势，其中以松属和桦木属最多，在各植被带均有分布。松属花粉最高含量出现在以红松为主的针阔混交林带的孢粉组合中；桦木属花粉则大量见于亚高山岳桦林带和以栎桦为主的阔叶落叶林带，但前者伴有耐寒、旱的小灌从杜鹃花属花粉，而在后者中则见有大量蕨类孢子。阔叶落叶林带的孢粉组合是以类型多、百分含量高的落叶乔木花粉和大量蕨类饱子为特征。亚高山针叶林带的孢粉组合中出现数量众多的云杉属花粉。在高山苔原带孢粉组合中虽然乔木花粉略占优势，但极少或不见蕨类孢子，与其他植被带比较，草本植物和小灌丛花粉明鲜较多，其中杜鹃属花粉含量在草本中占优势，其中出现苔原带的指示花粉——仙女木属。     

燕山地区表土花粉与植被间的数量关系

 根据表土花粉分析和植被样方调查,燕山地区各植被带的表土孢粉组合在总体面貌上代表了植被组成,但孢粉组合不等于植被组成,而影响其差异的原因是孢粉保存、孢粉产量、外来孢粉和孢粉鉴定。表土花粉的代表性因种属不同而差异颇大,乔木植物花粉中松(Pinus)、桦(Betula)、胡桃     

江苏宜兴龙池山现代植被表土孢粉的初步研究

江苏宜兴龙池山森林自然保护区表土花粉分析结果表明,表土孢粉植物群主要以栎属(Quercus)、松属(Pinus)、青冈属(Cyclobalanopsis)、栲属(Castanopsis)/柯属(Lithocarpus)、栗属(Castanea)占优势的木本植物组成,混生有枫香属(Liquidambar)、杨梅属(Myrica)、冬青属(Ilex)、女贞属(Ligustrum)、紫树属(Nyssa)、盐肤木属(Rhus)、黄连木属(Pistacia)等亚热带常见植物类型。研究区不同海拔高度的表土孢粉组合特征基本反映了当地现今的植物构成、植被面貌及其垂直分布规律。结合长江三角洲及其周边地区其他代表性表土花粉资料,首次提出以常绿阔叶木本植物与落叶阔叶木本植物含量之比(E/D),并结合重要优势、标志木本植物科属,初步识别和确立各地带性森林植被的表土花粉指标,为这一地区开展第四纪古植被和古气候等孢粉研究提供参考性依据。     

Modern pollen samples from alpine vegetation on the Tibetan Plateau

• 1 A set of 316 modern surface pollen samples, sampling all the alpine vegetation types that occur on the Tibetan Plateau, has been compiled and analysed. Between 82 and 92% of the pollen present in these samples is derived from only 28 major taxa. These 28 taxa include examples of both tree (AP) and herb (NAP) pollen types.
• 2 Most of the modern surface pollen samples accurately reflect the composition of the modern vegetation in the sampling region. However, airborne dust‐trap pollen samples do not provide a reliable assessment of the modern vegetation. Dust‐trap samples contain much higher percentages of tree pollen than non‐dust‐trap samples, and many of the taxa present are exotic. In the extremely windy environments of the Tibetan Plateau, contamination of dust‐trap samples by long‐distance transport of exotic pollen is a serious problem.
• 3 The most characteristic vegetation types present on the Tibetan Plateau are alpine meadows, steppe and desert. Non‐arboreal pollen (NAP) therefore dominates the pollen samples in most regions. Percentages of arboreal pollen (AP) are high in samples from the southern and eastern Tibetan Plateau, where alpine forests are an important component of the vegetation. The relative importance of forest and non‐forest vegetation across the Plateau clearly follows climatic gradients: forests occur on the southern and eastern margins of the Plateau, supported by the penetration of moisture‐bearing airmasses associated with the Indian and Pacific summer monsoons; open, treeless vegetation is dominant in the interior and northern margins of the Plateau, far from these moisture sources.
• 4 The different types of non‐forest vegetation are characterized by different modern pollen assemblages. Thus, alpine deserts are characterized by high percentages of Chenopodiaceae and Artemisia, with Ephedra and Nitraria. Alpine meadows are characterized by high percentages of Cyperaceae and Artemisia, with Ranunculaceae and Polygonaceae. Alpine steppe is characterized by high abundances of Artemisia, with Compositae, Cruciferae and Chenopodiaceae. Although Artemisia is a common component of all non‐forest vegetation types on the Tibetan Plateau, the presence of other taxa makes it possible to discriminate between the different vegetation types.
• 5 The good agreement between modern vegetation and modern surface pollen samples across the Tibetan Plateau provides a measure of the reliability of using pollen data to reconstruct past vegetation patterns in non‐forested areas.

     

太行山南麓山区不同植被恢复类型土壤理化和细根结构特征

在干旱半干旱地区,由于水分匮乏、土壤贫瘠等因素,将形成一定的裸地斑块,而这些斑块极易造成水土流失、滑坡等灾害,而具有不同植被覆盖的林地则能有效的保持水土。为完善干旱半干旱地区不同植被恢复类型下土壤理化和细根特征,选择太行山南麓山区具有代表性的裸露地、草地、荆条地、侧柏地、栓皮地和刺槐地等植被恢复类型,比较了各植被恢复类型下的土壤养分、粒径及细根状况等差异。研究表明:1)相对于裸露地,有植被覆盖的植被恢复类型拥有良好的土壤及细根状况。2)在不同植被类型中,刺槐林的有效氮转化速率较高;侧柏林有较高的细根参数;草地能够提高土壤中可吸收的磷组分。3)林地类型和土层均对土壤中含水率、黏粒、细根生物量和比根长产生极显著影响(P0.001)。4)各植被类型的对于土壤斑块的利用能力不同;不同植被类型中土壤及细根状况变化量具有一定的相似性,研究为生态恢复中植被类型的合理布局提供了新思路。     

不同植被恢复模式下煤矸石山复垦土壤性质及煤矸石风化物的变化特征

为了探讨植被恢复模式对煤矸石山复垦土壤和矸石风化物的影响,对煤矸石山6种主要植被类型(刺槐林、刺槐-柠条混交林、榆树-紫穗槐混交林、侧柏-刺槐混交林、荆条林、紫花苜蓿草丛)下土壤和煤矸石风化物的理化性状及重金属进行了比较研究。结果表明:(1)煤矸石山上种植植被可使土壤容重、土壤持水量和孔隙度明显改善。乔木模式更明显。矸石山植被恢复后,可明显增加土壤养分含量。不同植被模式下,土壤养分增加存在显著差异。侧柏-刺槐和榆树-紫穗槐混交模式效果较好。(2)植被对煤矸石风化物容重和机械组成改善作用依次为针阔混交林>乔灌林>乔木纯林>灌木林>草本。植被促进有机质与全氮积累依次为:侧柏-刺槐>刺槐>刺槐-柠条>榆树-紫穗槐>荆条>紫花苜蓿。荆条林下煤矸石风化物全P含量最大。荆条林与侧柏-刺槐混交林利于速效P积累。对速效K积累有利的是荆条林与榆树-紫穗槐混交林。(3)植被种植可以减少煤矸石风化物中重金属含量。榆树-紫穗槐混交模式对减低超标重金属Cd的效果好,其次是针阔混交林(侧柏-刺槐)。对于超标重金属As而言,侧柏-刺槐模式优于其它植被模式,基本达到重金属As不超标。     

A comparison of sedimentary DNA and pollen from lake sediments in recording vegetation composition at the Siberian treeline

Reliable information on past and present vegetation is important to project future changes, especially for rapidly transitioning areas such as the boreal treeline. To study past vegetation, pollen analysis is common, while current vegetation is usually assessed by field surveys. Application of detailed sedimentary DNA (sedDNA) records has the potential to enhance our understanding of vegetation changes, but studies systematically investigating the power of this proxy are rare to date. This study compares sedDNA metabarcoding and pollen records from surface sediments of 31 lakes along a north–south gradient of increasing forest cover in northern Siberia (Taymyr peninsula) with data from field surveys in the surroundings of the lakes. sedDNA metabarcoding recorded 114 plant taxa, about half of them to species level, while pollen analyses identified 43 taxa, both exceeding the 31 taxa found by vegetation field surveys. Increasing Larix percentages from north to south were consistently recorded by all three methods and principal component analyses based on percentage data of vegetation surveys and DNA sequences separated tundra from forested sites. Comparisons of the ordinations using procrustes and protest analyses show a significant fit among all compared pairs of records. Despite similarities of sedDNA and pollen records, certain idiosyncrasies, such as high percentages of Alnus and Betula in all pollen and high percentages of Salix in all sedDNA spectra, are observable. Our results from the tundra to single‐tree tundra transition zone show that sedDNA analyses perform better than pollen in recording site‐specific richness (i.e., presence/absence of taxa in the vicinity of the lake) and perform as well as pollen in tracing vegetation composition.     

黄土高原沟壑区森林带不同植物群落土壤氮素含量及其转化

为了探讨在黄土高原退耕还林还草过程中植物群落对土壤氮素含量及形态分布的影响,本文选择退耕历史较长的黄土高原沟壑区——安塞县洞子沟流域8种典型植物群落下0-10cm和10-20cm的土壤为对象,测定了土壤中有机氮、矿化氮、微生物量氮、硝态氮和铵态氮的含量。结果表明,从草本群落到乔灌草群落,土壤各形态氮素含量均增加,整体表现为乔灌草群落>灌草群落>草本群落。然而人工刺槐林的土壤氮素水平远低于自然恢复的乔灌草群落,甚至低于灌草群落。0-10cm 土层各形态氮素均高于10-20cm 土层。硝态氮对植物群落的变化最为敏感,可作为土壤氮素水平的敏感指标。土壤有机质、pH、容重与氮素含量极显著相关,各种氮素间极显著正相关。各种氮素占总氮的比例对总氮的变化有着不同的响应,有机氮、可矿化氮和微生物量氮占总氮的比例相对稳定,硝态氮占总氮的比例随总氮含量的增加而增加,铵态氮占总氮的比例随总氮含量的增加而降低。     

江西省不同类型退化荒山生态系统植被恢复与重建措施

对江西省 5种不同类型退化荒山生态系统进行综合治理 ,开展植被恢复与重建技术及理论研究。研究结果表明 :优选的植物组合及合理的配置并辅以工程措施是快速启动植被恢复进程 ,控制水土流失、重建退化荒山生态系统的有效措施。一林多用的树种组合 ,合理的生物体系设计和针、阔叶树种混交是改良地力 ,改善环境 ,促进退化荒山生态系统进展演替的优良途径。先进造林技术的应用和林农牧业结合的复合经营方式是提高综合治理效益 ,促进并维持生态恢复过程稳定的先决条件     

The relationship between pollen and extant vegetation across an arid urban ecosystem and surrounding desert in Southwest USA

Aim In this paper, we explore the relationship between pollen concentration in surface soil and extant perennial vegetation across a rapidly urbanizing arid ecosystem along with its surrounding agricultural and native Sonoran Desert land. We also investigate whether taxa behave as expected from known pollination characteristics (e.g. anemophilous vs. zoophilous) and whether the pollen–plant relationship differs between the undeveloped desert and agro‐urban regions. Location We used a probability‐based sampling scheme at 200, 900‐m² sites across the Central Arizona–Phoenix region, a 6400‐km² area of the south‐western USA. Methods Pollen–plant abundances were mapped across the study area using interpolation techniques, summary bar charts and scatterplots, then two statistical approaches were applied to examine the data quantitatively. Firstly, we used regression analysis of paired pollen concentration and plant cover data; secondly, pc‐ord was used on a cross‐matrix (contingency table) containing the presence/absence scores of both pollen and plants for each taxon at each site. Results Mapping and quantitative analysis revealed that pollen–plant relationships do vary both between anemophilous and zoophilous groupings and by individual taxon. They also revealed that distribution patterns of both pollen and plant abundance vary consistently across the three main landscape types (desert, urban, agricultural) and that pollen taxa groupings are consistent with pollination method and source plant distribution regardless of landscape type. Main conclusions These findings provide a broad range of comparative data to facilitate palynological reconstruction of past vegetation and aid in assessing types of prehistoric impacts on this vegetation. They also document that significant variation can occur in pollen rain across a city, even for taxa with widely distributed pollen, leading to the conclusion that forecasting pollen distribution patterns for allergy‐related pollen types using only one or a few pollen traps is likely to entail substantial error.     

Modern pollen assemblages from human-influenced vegetation in northwestern China and their relationship with vegetation and climate

Modern pollen spectra can improve the interpretation of fossil pollen records used to reconstruct past vegetation, climate and human impacts. It is important, therefore, to carefully examine the relationships between modern pollen spectra, vegetation, climate and human activity. Here, we present the results of an analysis of the pollen spectra of 143 surface pollen samples from farmland, wasteland, desert, steppe/meadow, forest and river valley along a transect from Lanzhou to Urumqi, in northwestern China. The modern pollen assemblages are mainly composed of Amaranthaceae, Artemisia, Poaceae, Asteraceae, Ephedra and Nitraria. The results indicate that in general the surface pollen assemblages of different vegetation types reliably represent the modern vegetation in terms of the composition of the main taxa and the dominant types. Farmland is dominated by cereal-type (≥?15%) and Amaranthaceae (≥?20%), while the pollen assemblages of wasteland (i.e. the vegetation immediately surrounding farmland) are mainly composed of Amaranthaceae (≥?25%), Artemisia (≥?20%), Poaceae (≥?10%), Asteraceae (≥?5%) and Cyperaceae (≥?5%). Amaranthaceae (≥?45%) and Ephedra (≥?10%) are the most important taxa in desert, and Cyperaceae (≥?35%) and Thalictrum (≥?2%) are the dominant pollen types in steppe/meadow. Forest and river valley samples are characterized by high frequencies of Picea (≥?10%) and Cyperaceae (≥?20%). Both constrained and partial canonical ordination techniques (RDA and partial RDA) of the main pollen types and environmental variables show that the modern pollen spectra are primarily controlled by mean annual precipitation (MAP). Cyperaceae, Thalictrum and Brassicaceae are positively correlated with MAP and negatively correlated with mean July temperature (T_July), while the representation of certain other types, such as Amaranthaceae, Ephedra and Nitraria, is negatively correlated with MAP and positively correlated with T_July. The Human Influence Index (HII) is significantly correlated with cereal-type pollen, and it can also differentiate human-influenced and natural vegetation. Our results provide a basis for improving the interpretation of fossil pollen records from arid northwestern China and similar regions.     

Coastal dune vegetation and pollen representation in south Buenos Aires Province, Argentina

Aim To establish the relationship between coastal dune vegetation and its pollen representation as an aid to interpret Holocene vegetation dynamics and environmental changes from pollen assemblages. Location The study area is situated on the temperate Atlantic coast of south Buenos Aires Province, Argentina (c. 39° S and 61°20′ W). Methods The vegetation of the active dune area adjacent to the beach was described on the basis of its floristic composition from 25 plots. Classification of the vegetation into distinct zones was carried out by cluster analysis. Surface samples were collected from each vegetation stand and analysed for their pollen composition. Pollen percentage data were analysed using principal components analysis in order to investigate the degree to which the different vegetation units can be distinguished by their pollen spectra. Pollen–vegetation relationships for selected taxa were explored using simple scatter plots and indices of association, under‐ and over‐representation. Indices of floristic diversity and palynological richness were used to assess the representation of the vegetation in the pollen spectra. Results and conclusions Five vegetation zones are defined on the basis of species composition and their quantitative variation: back shore, mobile dunes, slacks, semi‐fixed and fixed dunes. Pollen assemblages from back shore, mobile dunes and slacks are clearly differentiated from semi‐fixed and fixed dunes. Pollen assemblages differ considerably from the associated vegetation composition. Major discrepancies are caused by large differences in pollen and vegetation proportion of Hyalis argentea and Discaria americana. There is a considerable proportion of non‐local pollen in every spectrum. Pollen representation in the coastal dunes at Monte Hermoso is influenced by differences in pollen production, dispersal and preservation of individual taxa as well as by the spatial distribution of the vegetation, the topography of the dune system and the wind pattern. The pollen–vegetation relationship established in this study has important implication for understanding and interpreting fossil pollen records from coastal dune environments.