中国地层花粉数据集

地层孢粉数据是古植被和古气候重建等古环境研究的重要基础。孢粉数据库推动古环境研究从点到区域和全球尺度,从定性到定量,从而实现在大空间尺度和长时间序列上探索植被、气候和人类干扰的相互关系,以更好地理解地球系统的演变。该数据集整合了全国第四纪末期(5万年以来)共372个地层花粉序列,涵盖790个花粉类群,样点分布于中国30个省级行政区与领海。数据集包含地层花粉采样点的地名、经纬度坐标和海拔高度、数据来源、样品类型、沉积物长度、样品数量、测年方法及测年数量、时间跨度和参考文献,以及每个采样点的花粉含量百分比。数据主要来源于20世纪80年代至今。采样点集中分布在温带和亚热带森林、温带草原和荒漠以及青藏高原高寒植被区域;在深海到青藏高原不同海拔高度都有分布,但集中在海拔2 000 m之下。按照数据来源区分,原始数据样点178个,占47.8%;数值化数据194个,占52.2%。按照样品类型分类,多数样点为湖泊样品(151个)、冲积物/洪积物样品(99个)与泥炭样品(67个),占总样点数的85.2%。年代测定的主要方法为放射性碳同位素手段(占样品总数的93.8%),大部分记录有2–10个测年数据。采...     

中国第四纪晚期孢粉记录整理

孢粉数据库是重建过去植被格局以及研究古气候变化和大气圈-生物圈-人类活动相互关系的基础,而孢粉取样信息的记录和整理是建立孢粉数据库的重要前提。该文在收集我国1960–2008年发表的孢粉研究文献的基础上,整理分析了第四纪晚期,尤其是2万年以来(全新世为主)全国孢粉采样点的信息,包括采样地点名称、详细采样位置、省份、采样点经纬度和海拔高度、样品类型、取样深度、孢粉样品数量、14C测年数量及年代记录、覆盖的时间段和参考文献。总结发现,我国目前共有2324个表土/湖泊表层花粉采样点和987个第四纪晚期的地层沉积剖面和钻孔,其中高质量的地层孢粉采样点714个。虽然我国以及部分国际上从事第四纪研究的科学家尽了最大努力开展中国疆域的孢粉学研究,但由于人力、物力以及地形条件的限制,在我国仍然存在部分孢粉采样的"地理空隙",比如北方和西北荒漠地区、青藏高原无人区、中南部山区和东部人类活动频繁区域。然而,该数据信息库的不断完善,将为中国第四纪孢粉数据库的建立奠定良好基础。     

巢湖地区现代花粉—植被—人类活动关系研究

巢湖地区的孢粉研究多集中于化石孢粉, 相对缺少现代孢粉研究的支持。选取巢湖地区苔藓表土样品及湖泊表层底泥样品共49个进行孢粉分析, 探讨现代花粉与植被分布及人类活动的关系。结果表明: 花粉组合与当地植被有着很好的对应关系, 可以反映出当地的植被状况, 松属、栗属、落叶栎类、榆科、朴属、柳属、枫杨属、蔷薇科、十字花科、蒿属、紫菀属、禾本科(≤37 μm)、藜科和眼子菜属为花粉主要类型。现代花粉和钻孔花粉的匹配度较高, 可以为反演古植被古气候提供科学依据。花粉图谱和聚类分析将所有的采样点划分为4个土地利用类型。主成分分析相对划分出3个不同程度的人类活动影响区域: (1) 农田区—人类活动影响最强烈的区域; (2) 公园绿地区—人类活动影响较强的区域; (3) 次生林和湖心区—人类活动影响较弱的区域。巢湖地区十字花科花粉含量的变化在一定程度上可以区分人类活动的强弱, 有较强的指示作用。此外, 由于大规模开发、人工栽培以及次生林生长等因素均可能对花粉含量产生较大影响, 结合钻孔孢粉分析推测近1000年来巢湖地区松属、十字花科和谷物类禾本科花粉大量增加的主要影响因素极有可能是人为因素而非自然因素。     

南京低山丘陵区表土及捕捉器花粉谱的差异探究

选取南京丘陵地区29处样点,分别搜集表土及捕捉器样品,开展两种采样方式下孢粉组合与植被关系研究。结果表明,南京低山丘陵地区花粉类型以松属、栎属、枫杨属、榆属、蔷薇科、菊科、禾本科为主,表土花粉组合较好地反映了现代植被特征。主成分分析可以大致区分人工草坪区、农田区以及森林区的样品。农田区表土花粉浓度最低,每克仅为4 964粒,农田的翻耕以及微生物环境是造成其花粉浓度低的重要原因;森林区花粉浓度(每克29 176粒)及花粉通量(49 358粒/平方厘米/年)均很高。人类活动的增强可能会造成孢粉浓度的下降。在探究本地区历史时期人类活动时,可运用孢粉浓度以及与农作物相关的孢粉类型的变化来分析。所有捕捉器样品的乔木花粉百分比均低于其对应的表土样品,其中以松属尤为明显。     

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。     

南京紫金山山麓湖泊表层沉积物的孢粉分析*

本研究对南京紫金山山麓玄武湖和前湖共17个湖泊表层沉积物样品进行孢粉分析,旨在获得花粉组合新数据,揭示湖泊表层花粉与现生植被的关系,为开展第四纪湖泊地层孢粉学研究提供现代过程的参考.研究结果表明,花粉组合在剔除非自然分布的种植木本植物干扰花粉外,主要以木本花粉的松属(Pinus)和栎属(Quercus)占优势,其他常见木本植物有枫香属(Liquidambar)、栗属/栲属/柯属(Castanea/Castanopsis/Lithocarpus)、漆树科(Anacardiaceae)等.表土孢粉谱反映了研究区周边山地丘陵针叶、常绿-落叶阔叶林为主的植被,与现生北亚热带森林植被面貌对应良好.此外,陆生草本植物花粉主要是禾本科(Poaceae)和蒿属(Artemisia),湖泊湿生植物如水鳖属(Hydrocharis)、莎草科(Cyperaceae)等含量丰富.玄武湖与前湖中不同样点的主要木本植物花粉表现出优势类型高度一致、含量稳定、受采样位置的影响较小、指示地域植被类型的代表性较强等特点.通过对比南京地区已发表的紫金山及周边丘陵林下表土花粉分析结果,发现湖泊表土花粉组合受局部生境影响小,百分比含量较稳定,故其花粉信息在反映区域地带性植被的稳定性和可靠性方面更具优势.因此,开展表土花粉研究时应优先选择湖泊表层沉积物,藉此可提高基于孢粉重建区域地带性植被的代表性与可靠性.本研究结果为长江下游地区,尤其是南京地区解释第四纪孢粉组合与植被的对应关系提供了新数据和必要的现代过程参考.     

根据日本中部琵琶湖深井孢粉资料重建第四纪古植被和古气候及全球古气候对比

根据日本中部琵琶湖深井钻探资料研究了过去3Ma的古植被、地层及古气候。由湖底取得的200m和1400m样品的孢粉组合可分别划分出19个和37个带,反映了湖区及其周围自晚上新世以来的古植被和古气候演变史。在冰期阶时琵琶湖附近山区的典型植被为亚北极带,低地为冷温带。而在间冰期阶里山区一般为温带或冷温带植被,低地则主要由落叶和常绿树组成的温带和暖温带的植被。在进行过去3Ma古植被、古气候演变对比中,当地古气候史和以下资料显示出明显的一致,例如加勒比海、西太平洋及赤道海洋的氧同位素资料,地中海西部(Mallorca)的沉积旋回,欧洲中部的风成沉积序列,日本关东和新几内亚的海平面变化记录,以及在南美波哥大高地和以色列死海裂谷根据孢粉得出的古气候变化记录。     

基于文献计量学的近30年(1990-2020)第四纪孢粉学研究现状与展望

第四纪孢粉学利用现代和化石孢粉重建第四纪古植被、古气候和古环境,属于可持续发展的前沿学科领域。本文基于CiteSpace软件数据可视化和计量分析模块,以CNKI (中国知网)数据库与Web of Science核心数据库中1990–2020年间的共计6081篇第四纪孢粉学相关文献为基础,梳理了近30年来第四纪孢粉学的过去和现在,并探讨了未来发展趋势。研究结果表明,近30年第四纪孢粉学领域发文量呈增加趋势,中国的总发文量和国际影响力整体呈增长趋势;第四纪孢粉学研究主要集中于各大高校和科研院所,研究成果有明显的聚集性;中国科学院是外文发文量最多的国际机构。第四纪孢粉学近30年的研究主要涉及古植物学、古地理学、古生态学和古气候学等领域,古植被、古气候、古环境的定性和定量重建一直是国内外学者关注和研究的重点。表土花粉研究、花粉与人类活动、亚洲季风演变和孢粉分类学是近几年发刊的热点。虽然一些关键词如花粉产量、代表性以及现代花粉与植被和气候的定量关系等出现频次低,但对第四纪孢粉学十分重要。未来还需要进一步加强湖泊表层沉积物的花粉研究,探讨花粉与植被、气候的定量关系,为准确解译化石花粉提供坚实基础。...     

长白山北坡表土花粉组合及数量分析

吉林长白山植被垂直地带性是欧亚大陆从温带到寒带植被水平地带性的真实对照。通过对长白山北坡不同植物群落21个样点表土花粉组合及其与群落组成数量关系的分析,结果发现:(1)木本植物花粉占76.1%,木本植物与草本植物花粉比值(AP/NAP)约3.2,以桦属和松属为主;(2)岳桦云冷杉林和岳桦林花粉组合能较好地反映植物群落组成;红松云冷杉林花粉组合只能部分反映植物群落外貌;红松林的花粉组合不能较好反映植被特征;高山苔原花粉组合未能反映植物群落数量特征;(3)主要花粉类型中松属和桦属花粉具超代表性,云杉属、杜鹃花科和蔷薇科花粉具低代表性;(4)通过花粉相对含量,DCA分析能较好地区分不同植被类型,但是红松林与红松云冷杉林、岳桦云冷杉林无法区分。本研究可为本区古植被与古环境恢复提供新证据。     

样地尺度现代表土花粉与植物群落的定量关系

建立现代植被与表土花粉的精确关系,是基于孢粉记录定量重建古植被与古气候的基础与关键。截止目前,植物群落样方记录较少参与到现代植被与花粉的统计分析中,限制了其精确关系的定量表达。本文通过中国东北样带的森林、草甸草原、典型草原和荒漠草原33个表土样品分析及植被样方调查,基于Bray-Curtis相异系数,研究了东北样带现代表土花粉与植物群落组成和数量之间的定量关系。结果表明: 由于花粉传播距离和花粉产量大小的不同,单个样点的所有科属、优势和常见科属、少见和稀有科属,在组成和数量上的关系存在差异。不同植被类型间差异显著,草甸草原在组成上差异较大,而所有科属、优势和常见科属的数量关系在森林中差异较大,少见和稀有科属的数量关系则在草甸草原中差异较大。不同科属的植被-花粉关系在组成和数量上的趋势基本一致,根据Bray-Curtis相异系数可将该地区花粉类群划分为3类: 超代表性类型、低代表性类型和适中代表性类型。该系数可以获得样方水平和物种水平上植被-花粉的物种组成和数量关系,是定量描述植被-花粉关系的有效指标之一。     

The role of landscape structure in determining palynological and floristic richness

The associations between floristic and palynological richness and landscape structure were studied based on modern pollen?Cvegetation data from a patchy cultural landscape in southern Estonia (northern temperate vegetation zone). Nine study sites (small lakes and their surrounding vegetation) represent land cover gradient from closed forest to semi-open vegetation. Floristic richness (number of species) and floristic richness of pollen types (number of pollen-equivalent taxa) were used to describe the vegetation within the radius of 250?m from the pollen sampling sites. Palynological richness was calculated to describe the modern pollen samples diversity. Landscape structure was estimated on the basis of landscape openness and three landscape diversity measures: richness of community patches, Simpson evenness of community patches and Simpson diversity of community patches. To study the effect of the spatial scale of landscapes on the vegetation?Clandscape and pollen?Clandscape associations, landscape structure was estimated within eight radii (250?C2,000?m) around each lake. The results showed that landscape openness was the most important determinant of both floristic richness and palynological richness in southern Estonia and that landscape diversity estimated by Simpson diversity index was also significantly associated with the richness estimates. Floristic and palynological richness were significantly positively correlated with landscape structure within the radii greater than 1,000?m from the pollen sampling sites, which is similar to the estimated Relevant Source Area of Pollen in southern Estonia. We conclude that within one floristic or climatic region, palynological richness gives reliable estimates about the variation in floristic richness and landscape structure; however, caution must be taken when comparing pollen-inferred vegetation diversities from different regions or when interpreting fossil pollen records from times with highly different vegetation associations.     

Modern pollen-based biome reconstructions in East Africa expanded to southern Tanzania

New detailed biome reconstructions are proposed in East Africa from modern pollen data derived from 150 sites located in northern Kenya (40 sites), north-western Uganda (51 sites) and southern Tanzania (59 new sites presented as pollen diagram), which are representative of the major vegetation associations occurring in seven phytogeographical regions, mosaics or centres of endemism. We use the standard biomisation method previously published for the African continent, but we reconsider the taxa assignment to plant functional types. We include in this approach all identified taxa (408) except aquatics, ferns and exotic taxa. The method is validated by comparison with local vegetation data and we show that 124 (82.6%) sites are assigned to the correct biome and that for all the biomes under investigation, the number of correct assignments always exceeds the number of incorrect ones. When an incorrect biome reconstruction occurs, mainly toward drier biomes, this is generally linked to the local open/degraded structure of the original vegetation or to the occurrence of a mosaic of open/closed vegetation. In turn, most of the reconstructions of more humid/closed biomes than the corresponding local vegetation (8.6%) remain unexplained. A comparison of our reconstructed biomes with the main East African vegetation types of White's map indicates that 121 (80.6%) sites are assigned to the correct biomes. However, the majority of sites are incorrectly reconstructed compared to Olson and IGBP maps from satellite data, mainly due to incorrect allocation of the land cover classes compared to the potential vegetation. The application of this method to our pollen data set demonstrates that modern pollen assemblages can successfully reconstruct the main modern East African vegetation types.     

Numerical Characteristics of Pollen Assemblages of Surface Samples from the West Kunlun Mountains

A total of 31 suface sediment samples were collected from West Kunlun Mountain in south Xinjiang Autonomous Region in northwest China. These samples are from seven types of vegetation: Picea schrenkiana Fisch. et Mey. forest, Sabina Spach. woodland, sub-alpine steppe, alpine meadow, desert vegetion, cushion-vegetation and vegetation adjancent to glaciers. Pollen percentages and pollen concentrations were calculated in all samples. The dominant pollen types in the region are Chenopodiaceae, Artemisia, Picea, Ephedra, Gramineae, Cyperaceae, Rosaceae, Leguminosae, Compositae etc. In order to reveal the relationship between pollen composition and the vegetation type from which the soil sample was collected, principal component analysis and group average cluster analysis were employed on the pollen data. The results revealed that the major vegetation types in this region could be distinguished by pollen composition: a. Samples from desert vegetation were dominated by pollen of Chenopodiaceae (about 60195%). The percentages of all other pollen types were low. b. Picea forest samples were rich in Picea pollen (about 20%) Sabina forest had more Sabina pollen grains than other vegetation types (about 5%, others <1%). Pollen percentages of Artemisia, Chenopodiaceae and Ephedra were comparatively higher (each about 20%) in these samples from the two types of vegetations. C. Pollen percentages of Artemisia, Cyperaceae, Gramineae and Chenopodiaceae were high in both sub-alpine steppe and alpine meadow. But steppe containal more Artemisia and Chenopodiaceae (steppe 33.75% and 32.30%, meadow 15.57% and 19.48% in average), less Cyperaceae and Gramineae (steppe 2.58% and 7.60%, meadow 22.35% and 12.93% in average) than meadow. d. Samples from cushion-vegetation and vegetation adjacent to glaciers were mainly composed of pollen grains transported from other sites. It was not easy to distinguish them from other vegetation types. Principal component analysis and cluster analysis distinguish samples from Picea forest, Sabina woodland, sub-alpine steppe, alpine meadow and desert vegetation. Therefore we think it will be possible to apply the module to reconstruct past vegetation in this region and other similar regions. Regression analysis was also applied to reveal the relationships between pollen and plant percentages of Artemisia, Chenopodiaceae, Cyperaceae and Gramineae. The results indicated that a linear relationship existed between pollen and plant percentages for Artemisia, Chenopodiaceae and Cyperaeeae.     

Vegetation and environment changes inferred from pollen records since 3000 cal. yr BP in Kanas wetland,Xinjiang

Aims Climate change can significantly affect the vegetation worldwide. Thus, paleovegetation and paleoclimate reconstruction should consider the quantitative relationship between modern vegetation and climate. The specific objectives of this study were (i) to assess the influence of environmental variables on pollen assemblages in the Kanas region, (ii) to reconstruct the evolution of vegetation over the past 3000 years using pollen records and (iii) to quantify historical climate change (including mean annual temperature and total annual precipitation) using a weighted averaging partial least squares regression method (WAPLS) applied to fossil pollen data from the Kanas wetland in Xinjiang, China.     

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.     

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.

     

立地尺度植被重建模型MARCO POLO的应用分析——以柴达木盆地为例

立地尺度植被定量重建是对利用孢粉进行古气候和古环境研究的一个重要补充。一些新的定量重建模型相继提出,但其适用性仍需进一步验证。以柴达木盆地24个样方表土孢粉及4个湖泊表层沉积孢粉为研究对象,利用MARCO POLO模型重建立地尺度植被盖度并分析该模型的适用性。研究结果表明,由于地形开阔且风力较大,干旱区的大型湖泊沉积物中往往容易富集超代表性孢粉,使这些孢粉的区域信号增强,从而降低孢粉类型筛选的正确率。若湖泊与样方间的距离较近,湖泊表层孢粉能够更好地反映样方所在区域的孢粉特征,则有利于提高孢粉类型筛选的正确率。MARCO POLO模型中的孢粉代表性R值是将孢粉含量转化为植被盖度的关键参数。由于受到孢粉自身生产、传播、保存以及外部环境等多方面因素的影响,不同样方的R值可能差异很大。因此在运行该模型前需保证R值能够准确反映立地尺度中各孢粉类型与植被盖度的关系。仅在以柴达木盆地为代表的干旱区对该模型进行检验,今后仍需要在不同植被或气候区进行深入研究以全面了解该模型的适用条件。     

The mid‐Holocene vegetation of the Mediterranean region and southern Europe,and comparison with the present day

Aim To contribute to the intense debate surrounding the relative influence of climate and humans on Mediterranean‐region land cover over the past 6000 years, we assess the Holocene biogeography and vegetation history of southern Europe by means of an extensive pollen record dataset. Location The Mediterranean biogeographical zone and neighbouring parts of Iberia, the Alps and Anatolia, between 30° N, 48° N, 10° W and 45° E. Methods We compiled a southern European pollen record dataset using available pollen databases (124 sites) and other sources (74 sites), with improved spatial coverage and dating control compared with earlier studies. We used only those sites that had pollen data for both 0 ka and 6 ka. We reconstructed mid‐Holocene and present‐day biomes, arboreal pollen percentages and distribution and relative abundance of 11 key woody taxa, with anomaly maps. Results Northern temperate forest biomes extended further south at the mid‐Holocene than at present, but not as far as earlier studies suggested. Sclerophyllous vegetation occurred along the Mediterranean coast throughout the region at 6 ka. Arboreal pollen percentages were up to 50% higher than at present. At 6 ka, Olea, Fagus and Juniperus had smaller distributions and/or abundances; Abies, Cedrus and both deciduous and evergreen Quercus had larger distributions and/or abundances; Phillyrea, Pistacia and Cistus showed minimal difference; and Pinus showed a cosmopolitan distribution with variable abundance. Main conclusions Temporal difference analysis is more meaningful when only sites containing samples for all time slices are analysed. During the mid‐Holocene, southern Europe was more heavily forested with temperate vegetation than it is at present, but drought‐tolerant xeric vegetation was still widespread along the southern margins of the region. Although human land use may have caused the degradation of land between the mid‐Holocene and the present, the mere presence of xeric vegetation in the Mediterranean region does not require human impact. This challenges the commonly held belief that modern Mediterranean vegetation represents a ‘degraded’ state.