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1.
中国北方几种主要森林群落表土花粉组合特征研究   总被引:30,自引:11,他引:19       下载免费PDF全文
中国北方68个不同森林群落表土花粉研究表明,东部森林区森林群落中乔木花粉百分比多数大于30%,草本花粉百分比小于50%;草原区河谷林和低山林带乔木花粉百分比低于30%,草本植物花粉高于50%。松、云冷杉林和桦木林花粉组合中的优势成分也是群落中的优势植物;落叶松林中蒿花粉含量最高,其次为松、落叶松;山杨林中松、桦是最主要花粉类型;栎、胡桃、鹅耳枥及青檀林中,除建群种外,松是最主要的乔木花粉类型,中华卷柏也较多;阔叶杂木林与油松阔叶混交林花粉组成相似,松、桦、中华卷柏是最主要的花粉类型。降趋对应分析、主坐标分析和聚类分析研究表明云冷杉、落叶松和桦林花粉组合及所代表的生境具有一定的相似性,为最耐寒喜湿类型;沙枣、榆树疏林和草原区人工杨树林花粉组合及所代表的生境为最喜干旱类型;山杨林较桦木林略喜暖干,栎林、鹅耳枥林和青檀林较山杨林更喜暖干,胡桃楸林为所有森林类型中最喜暖类型,但喜湿性低于桦木林高于栎林。森林区松蒿比(P/A)大于0.1,草原区松蒿比小于0.1。松林、油松阔叶混交林和阔叶杂木林以高松蒿比、高蕨类与草本比值(F/H)和低蒿藜比(A/C)为特征,云冷杉、落叶松和桦林以低松蒿比、低蕨类与草本比值和高蒿藜比为特征,栎、胡桃、鹅耳枥、杨、青檀等阔叶林以高松蒿比、高蒿藜比和低蕨类与草本比值,可与落叶阔叶杂木林、油松阔叶混交林、松林、桦林和针叶林区分开。但这些比值的可操作性,有待进一步研究。  相似文献   

2.
长白山生态景观格局动态变化分析   总被引:1,自引:0,他引:1  
长白山独特的地质和地理条件,形成了特有的自然景观,植被垂直带谱在亚洲具有代表性。通过1977年MSS、1985年TM及1999年TM三期遥感影像,结合实地调查建立解译标志,进行分类并计算景观指数,分析了长白山地区近30年来的景观结构变化。分析表明:从景观面积变化率来看,1977-1985年间,水体、苔原、居民点、针叶林和草地的面积减少,耕地和针阔混交林的面积增加显著,阔叶林、岳桦林、道路、裸地增加;1985-1999年间,水体、裸地、针阔混交林和阔叶林的面积减少,其他类型面积增加。景观格局变化表明,人为活动对景观格局产生的影响,已成为景观格局变化的主要驱动因子。  相似文献   

3.
青藏高原南部第四纪花粉植物群及古气候   总被引:3,自引:0,他引:3  
本文选择了青藏高原南部具有代表性的6个花粉剖面,应用主成分分析处理这些剖面的花粉数据,重建了这些地区的古植被和古气候。研究表明,在青藏高原南部,早、中更新世的植被类型主要是松林、云杉林、铁杉林、桦林、桤木林和栎林,晚更新世和全新世的植被类型主要是高山灌丛草原、小半灌木草原、杂类草草甸、亚高山灌丛和落叶阔叶灌丛;在早、中更新世气候条件良好,有森林生长,晚更新世以后气候明显恶化,基本无森林生长。  相似文献   

4.
云南省玉龙雪山表土花粉垂直散布与植被关系研究   总被引:4,自引:4,他引:0       下载免费PDF全文
对云南省玉龙雪山地区8个垂直植被带下采集的49个表土样品进行表土孢粉的垂直散布研究,同时选择43个受人类活动干扰较少的样品和20个主要木本花粉类型进行了降维对应分析(DCA)。结果表明,玉龙雪山地区不同垂直植被带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带类型。在植物稀疏、花粉产量低的高山杜鹃灌丛植被带中,孢粉组合以外来的松属、冷杉属、落叶松属、云杉属和铁杉属等为主;   冷杉林、落叶松林、云杉林和铁杉林等植被带孢粉组合的指示性成分分别是冷杉属、落叶松属、云杉属和铁杉属花粉,它们对应的峰值分别为13.6%,4.7%,39.4%和11.5%;   针阔混交林、中山湿性常绿阔叶林的孢粉组合分别以高含量的常绿栎类、栲/石栎属为特征,并都含有多种落叶阔叶乔木和灌木的花粉,但后者比前者所包含的阔叶乔木与灌木成分更多,且蕨类孢子的峰值也出现在中山湿性常绿阔叶林中;   云南松林的孢粉组合中除松属外很少有木本花粉出现。DCA排序结果较好地反映了现代植被与环境之间的相互关系,认为温度是决定不同植被带样点分布的最重要因素,这与垂直植被带随着海拔升高、温度逐渐降低而发生更替的规律是一致的。  相似文献   

5.
基于东北过伐林区吉林省汪清林业局187块蒙古栎林的样地调查数据,结合单木生物量模型,研究蒙古栎林的林分生物量和估计模型.结果表明: 蒙古栎林的平均生物量为: 树干 178.73Mg/hm2, 树枝13.766Mg/hm2, 树叶 5.159Mg/hm2, 树根 29.373Mg/hm2, 全部为 227.028Mg/hm2. 采用联立方程组方法,建立了相容性林分生物量模型.该模型包括树干、树枝、树叶、根和全部各分量,自变量为林分公顷株数和断面积.各模型的预估精度均在95%以上,95%的误差分布在[-24.144,23.712],[-5.146,5.578],[-1.743,1.919],[-3.493,3.440]和[-30.156,30.166](置信水平为95%).由于模型的自变量林分公顷株数和断面积是森林调查中的常规因子,也是传统森林生长收获模型中的重要变量,因此,一方面可利用建立的模型和固定样地通过统计推断获得森林经营单位或区域尺度的森林生物量,或基于小班调查数据进行估算; 另一方面可以和传统的生长收获模型相结合,预测林分生物量的变化.为气候变化下林分、森林经营单位和区域生物量和碳贮量的计量和预测提供了方法和依据.  相似文献   

6.
云南西部羊邑和龙陵地区晚上新世植被和古气候   总被引:4,自引:2,他引:4       下载免费PDF全文
云南西部羊邑和龙陵地区晚上新世孢粉组合均以被子植物占优势,蕨类和裸子植物次之,藻类类群少。龙陵孢粉组合比羊邑孢粉组合含有更丰富的亚热带被子植物成分;裸子植物类群相对较少;蕨类类群较多,但孢子含量低。与研究地区现生植被对比研究的结果显示羊邑孢粉组合的大部分类群来自常绿针阔叶混交林,现在分布于羊邑地区海拔2800-3100m的地带,其余部分来自海拔3200m以上的云冷杉林;而龙陵孢粉组合的大部分类群来自山地湿润常绿阔叶林,分布于今日龙陵地区海拔1600-2500m的地带,其余部分来自海拔2300-2900m的常绿针阔叶混交林。这些云南西部晚上新世植被反映了湿润的亚热带山地立体气候。  相似文献   

7.
长白山岳桦苔原过渡带动态与气候变化   总被引:11,自引:0,他引:11  
应用样带网格调查方法 ,对长白山岳桦苔原过渡带上岳桦径级结构、分布格局以及过渡带的环境因子进行调查 ,并与最近几十年的极端低温进行了对比研究 ,用格局的差异和径级结构的动态变化来揭示全球变暖对岳桦苔原过渡带的影响。结果表明 :全球气候变暖对长白山岳桦苔原过渡带产生很大影响 ,气候变暖使得岳桦苔原过渡带中的岳桦分布主要以幼苗和幼树为主 ,其中岳桦的径级分布呈倒J字型 ,过渡带中岳桦种群格局呈聚集型分布。整个岳桦种群随着全球气候变暖有一种整体向上迁移的趋势 ,尤其以岳桦苔原过渡带最为明显 ,岳桦苔原过渡带变宽 ,岳桦向苔原侵入的程度加剧。  相似文献   

8.
以云南阳宗海1020 cm长的湖泊沉积物岩芯为研究对象,由7个木屑和树叶残体样的AMS14C测年建立岩芯年代框架,以18~19 cm间隔获取52个样品作花粉/炭屑分析,重建了阳宗海流域过去13000年的植被、气候以及森林火灾历史。研究结果表明,过去13000年植被演替、气候变化和森林火灾可分为5个阶段:1)13200~11000 cal.a B.P.,植被以常绿、落叶阔叶混交林为主,气候温凉湿润,森林火灾多发,后期(12300~11000 cal.a B.P.)随着温度和湿度的降低,森林火灾发生愈加频繁;2)11000~8000 cal.a B.P.,松林扩张,阔叶林缩小,气候较上阶段温暖偏干,森林火灾发生次数明显降低;3)8000~5000 cal.a B.P.,松林和常绿阔叶林占优势,且出现暖热性的枫香林,流域内气温升至13000 cal.a B.P.以来的最高值,湿度进一步降低,但森林火灾发生频率低;4)5000~800 cal.a B.P.,松林扩张至最盛,常绿阔叶林收缩,落叶阔叶林成分增加,气温和湿度均明显下降,森林火灾发生频率有所增加;5)800 cal.a B.P.至今,松林和常绿阔叶林收缩,落叶阔叶成分增加,草本植物中禾本科迅速上升,可能与人类活动有关,森林火灾发生频率低。阳宗海花粉/炭屑记录重建的植被、气候和森林火灾史表明,在滇中地区,落叶阔叶成分易引起森林火灾,冷气候导致多发的森林火灾,冷干气候是宜森林火灾发生的气候条件。  相似文献   

9.
南亚热带森林植被恢复演替中土壤有机碳组分及其稳定性   总被引:3,自引:0,他引:3  
以鼎湖山森林植被恢复演替过程中的松林(初期)、混交林(中期)和季风林(后期)为研究对象,通过测定其土壤总有机碳(TOC)、易氧化有机碳(ROC)和不易氧化有机碳(NROC)及凋落物13C-NMR分析,以期阐明森林植被恢复演替过程中土壤有机碳组分变化规律及其原因。结果表明:(1)3个森林土壤ROC含量差异不显著;由松林向季风林演替过程中,ROC占TOC的比例下降。松林新鲜凋落物层的烷氧基碳含量(57.03%)高于季风林(49.10%)和混交林(54.50%)。(2)3个森林土壤NROC含量差异显著,大小顺序为:季风林混交林松林。混交林和季风林凋落物半分解层和已分解层的惰性指数明显高于松林。TOC趋势与NROC一致。南亚热带森林由松林向季风林恢复演替过程中,土壤有机碳的稳定性增加,惰性有机碳的持续积累可能是季风林和混交林土壤TOC积累的一个重要过程。  相似文献   

10.
气候变化对大兴安岭北部沼泽景观格局的影响   总被引:5,自引:3,他引:2       下载免费PDF全文
大兴安岭北部地区由于在高纬、高海拔双重因素作用下,形成了独特的山地沼泽类型。首先使用Logistic回归模型分析了沼泽湿地与18种环境因子(11种地形因子和7种气候因子)的关系,结合CGCM3未来气候模型(加拿大气候模拟和分析中心推出的第三代全球气候耦合模型)预测未来分布,然后利用Fragstats软件计算景观格局的变化。所建模型具有很高的预测精度(ROC为0.96),预测结果表明:到2100年,SRESB1情景下,大兴安岭北部沼泽的潜在分布面积减少54.16%,南部相对平坦的丘陵和山间平原的沼泽大量消失;SRESA1B情景下,面积减少59.62%,南部林区的沼泽几乎全部消失;SRESA2情景下,面积减少73.51%,沼泽几乎完全退化到北部海拔较高处。另外,沼泽景观格局随气候变暖,平均斑块面积变小,形状指数减小,聚集度减少但幅度不大,这说明沼泽分布趋于破碎化,斑块的形状趋向于简单化,沼泽分布由边缘向中心收缩。  相似文献   

11.
By mapping and summarizing 478 pollen counts from surface samples at 406 locations in eastern North America, this study documents the relationships between the distributions of pollen and vegetation on a continental scale. The most common pollen types in this region are pine, birch, oak, and spruce. Maps showing isopercentage contours or isopolls for 13 important pollen types reflect the general N-S zonation of the vegetation. The maps and tabulations of average pollen spectra for the six major vegetational regions indicate high values for the following pollen types in each region: (1) tundra-nonarboreal birch, sedge, and alder; (2) forest/tundra-spruce, nonarboreal birch and alder; (3) boreal forest-spruce, jack pine (type), and arboreal birch with fir in the southeastern part; (4) conifer/hardwood forest-white pine, arboreal birch, and hemlock with beech, maple, and oak in the southern part; (5) deciduous forest-oak, pine, hickory, and elm, with beech and maple in the northern part, and highest values of oak and hickory west of the Appalachian crest; and (6) southeastern forest-pine, oak, hickory, tupelo, and Myricaceae. In some cases, less abundant pollen types are diagnostic for the region, e.g., bald cypress in the southeast. In the conifer-hardwood region and southward, pollen of weeds associated with deforestation and agriculture is abundant. The maps also show that much of southeastern U.S. and the area just to the east of Hudson Bay are in need of additional sampling. At 51 of the sites, absolute pollen frequencies (APF; grains/ml lake sediment) were obtained. These confirm the major conclusions from the percentage data, but differences are evident, e.g., the percentages of alder pollen peak in the tundra whereas alder APFs peak in the boreal forest, and spruce percentages peak in the forest-tundra whereas spruce APFs peak in the boreal forest. Because the APF data reflect the patterns of absolute abundance of individual taxa in the vegetation as well as the overall forest densities, future counts of modern pollen should include APF determinations. The effects of sedimentation processes on APF quantities indicate that APF samples should be obtained from moderate size lakes of similar morphology and hydrology and that, in each lake, several samples from the profundal zone should be pooled to create a sample representative of that lake.  相似文献   

12.
Climatically driven Late Pleistocene and Holocene vegetation changes were reconstructed based on pollen records from the sediments of Lake Kotokel and Cheremushka Bog, located on the eastern shore of Lake Baikal. The described paleoenvironmental record has higher resolution than records collected from Lake Baikal and unites individual events identified in prior studies of bottom and onshore cores. Remarkable shifts in landscapes and expansions of index plants are as follows. Forest tundra and/or forest steppe landscape with birch, spruce, Artemisia, and Poaceae prevailed at ca. 50–25 14C kyr BP. Tundra and/or steppe vegetation dominated by Artemisia and Poaceae was typical for the Last Glacial Maximum. The expansion of shrub birch and willow occurred at ca. 15.5 14C kyr BP. Two peaks of spruce expansion at ca. 47.5–42.4 14C kyr BP (Karginian time) and at ca. 14.5–13 ka (Bølling-Allerød warm intervals) suggest that the condition were more humid than today. A slight increase in Artemisia at ca. 11–10.5 14C kyr BP (13–12 ka) was indicative of the Younger Dryas event. An expansion of birch forests with fir at ca. 12–6.4 ka suggests higher humidity. The currently dominant Scots and Siberian pine forests with birch expanded since 6.4 ka.  相似文献   

13.
Quaternary deposits on the Pacific slope of Washington range in age from the earliest known interglaciation, the Alderton, through the Holocene. Pollen stratigraphy of these deposits is represented by 12 major pollen zones and is ostensibly continuous through Zone 8 over more than 47,000 radiocarbon yr. Before this, the stratigraphy is discontinuous and the chronology less certain. Environments over the time span of the deposits are reconstructed by the comparison of fossil and modern pollen assemblages and the use of relevant meteorological data. The Alderton Interglaciation is characterized by forests of Douglas fir (Pseudotsuga menziesii), alder (Alnus), and fir (Abies). During the next younger interglaciation, the Puyallup, forests were mostly of pine, apparently lodgepole (Pinus contorta), except midway in the interval when fir, western hemlock (Tsuga heterophylla), and Douglas fir temporarily replaced much of the pine. Vegetation outside the limits of Salmon Springs ice (>47,00034,000 yr BP) varied chiefly between park tundra and forests of western hemlock, spruce (Picea), and pine. The Salmon Springs nonglacial interval at the type locality records early park tundra followed by forests of pine and of fir. During the Olympia Interglaciation (34,00028,000 yr BP), pine invaded the Puget Lowland, whereas western hemlock and spruce became manifest on the Olympic Peninsula. Park tundra was widespread during the Fraser Glaciation (28,00010,000 yr BP) with pine becoming more important from about 15,000 to 10,000 yr BP. Holocene vegetation consisted first of open communities of Douglas fir and alder; later, closed forests succeeded, formed principally of western hemlock on the Olympic Peninsula and of western hemlock and Douglas fir in the Puget Lowland. Over the length of the reconstructed environmental record, climate shifted between cool and humid or relatively warm, semihumid forest types and cold, relatively dry tundra or park tundra types. During times of glaciation, average July temperatures are estimated to have been at least 7°C lower than today. Only during the Alderton Interglaciation and during the Holocene were temperatures higher for protracted periods that at present.  相似文献   

14.
The Kenai Peninsula of south‐central Alaska is a region of high topographic diversity with a complex glacial history. The sedimentary record of two small lakes [Sunken Island (SIL; 76 m a.s.l.) in the Kenai Lowlands; Choquette (CL; 527 m a.s.l.) in the Caribou Hills upland] exemplifies the postglacial development of the conifer–hardwood forest over an elevational range there. A herb–shrub tundra was established at both sites after deglaciation. By ~10.7 ka, poplar (Populus sp.) and alder (Alnus) dominated the lowland forest, while alder with minor poplar occurred at the upland site. Lake levels lower than today occurred during the early Holocene until ~8 ka. Subsequently at SIL, the near‐modern Kenai birch (Betula kenaica) – white spruce (Picea glauca) forest maintained prominence throughout the Holocene. However, at CL, alder dominated with dwarf birch and other subshrubs; small amounts of white spruce arrived ~5.2 ka. Black spruce (Picea mariana) grew around SIL by ~4 ka, but never gained prominence at CL. Fire, a prominent agent of disturbance in the Kenai Lowlands since ~8 ka, was essentially absent at the hardwood‐dominated upland site before ~6 ka, and rare thereafter. This suggests an important link between fire and spruce in Kenai forests.  相似文献   

15.
A pollen analytical investigation of the sediments of Berry Pond, Berkshire County, Massachusetts, has demonstrated a sequence of pollen assemblage zones similar to those detected elsewhere in New England. From about 13,000 to 12,000 yr B.P. the vegetation of the region was treeless, probably tundra. By 11,500 yr tundra had been replaced by open boreal forest. Closed boreal forest became dominant by 10,500 yr. Boreal forests were replaced by mixed coniferous and deciduous forests with much white pine about 9600 yr ago. A “northern hardwoods” complex with much hemlock, beech, and sugar maple succeeded the mixed forests 8600 yr ago. Hemlock declined very rapidly approximately 4800 yr ago and was replaced by birch, oak, beech, ash, and red maple. This decline may have been biologically rather than climatically induced. There is a slight maximum of pine (much of it pitch pine) from 4100 to 2600 yr ago, perhaps indicative of warmer and/or drier conditions. There were slight changes in the forests about 1600 yr ago as chestnut immigrated and spruce and larch increased slightly. European land clearance and subsequent land abandonment are detectable in the uppermost levels.  相似文献   

16.
Shane, Linda C. K. 1987 03 01: Late-glacial vegetational and climatic history of the Allegheny Plateau and the Till Plains of Ohio and Indiana, U.S.A. Boreas , Vol. 16, pp. 1–20. Oslo. ISSN 0300–9483.
Pollen evidence from the Allegheny Plateau and the Till Plains south of the Great Lakes shows marked post-glacial vegetation gradients. C. 15,500–11,000 B.P .: On the Plateau, spruce forest was rapidly established, persisted for 2,000 years, then began a gradual change to deciduous-conifer forest. On the Till Plains, open spruce forest tundra closed slowly over 1,000 years, declined rapidly c . 13,500 B.P., and a deciduous open woodland developed. C. 11,000–10,300 B.P .: On the Till Plains, a brief cooling is recorded by increases in the abundance of spruce and fir, contemporaneous with the European Younger Dryas. No clear change is seen on the Plateau. 10,300–4,000 B.P .: Warming and/or drying occurred in both areas, as hemlock and jack/red pine trees immigrated, followed by white pine. Conifers disappeared from the Till Plains by 9,800 B.P., but pine and hemlock trees may have persisted on the Plateau. After 10,000 B.P. mixed deciduous forest was established across the entire region. Between 8,000 and 4,000 B.P., further warming/drying is indicated on the Till Plains with development of open oak forest and lake shallowing, and on the Plateau by a minor increase in herbs, lake shallowing, and reduction in pine.  相似文献   

17.
A 14-m-thick section of marine and nonmarine sediments of the Gubik Formation of northern Alaska, exposed in bluffs near Ocean Point on the Colville River, has been studied by means of pollen analysis. Pollen from the marine sediments, of probable late Pliocene age, records a boreal forest of spruce and birch with minor amounts of alder in the adjacent terrestrial vegetation. Pine and perhaps true fir were probably at or near their northern limit here, but hemlocks and hardwoods were absent. The suggested environment for the Arctic Slope during the time represented by the marine sediments is similar to that of present-day Anchorage. Pollen floras from the overlying fluvial strata, of early or middle Pleistocene age, record predominantly herbaceous taxa indicating tundra conditions probably more severe than those of the present day. These deposits were most likely contemporaneous with glacial conditions in the Brooks Range to the south. Pollen of woody taxa (spruce, alder, birch, heaths) is rare through most of the section, although birch and alder percentages similar to those found in modern river sediments indicate an interstadial or interglacial warming in midsection. Inland climates during glacial episodes may have been similar to those of the present Arctic coast.  相似文献   

18.
The extinct Harrington's mountain goat (Oreamnos harringtoni Stock) is predominantly known from dry cave localities in the Grand Canyon, Arizona, in addition to two sites in the Great Basin, Nevada, and from San Josecito Cave, Nuevo Leon, Mexico. A dry shelter in Natural Bridges National Monument, on the central Colorado Plateau, southeastern Utah, preserves numerous remains of the extinct mountain goat in addition to pack rat middens. Remains from a 100-cm stratigraphic profile indicate that O. harringtoni lived on the plateau >39,800 yr B.P., the oldest directly dated find of extinct mountain goat. Plant macrofossils indicate that Engelmann's spruce (Picea engelmannii), limber pine (Pinus flexilis), rose (Rosa cf. woodsii), and Douglas fir (Pseudotsuga menziesii) grew during the late Pleistocene where a riparian and a pinyon-juniper (Pinus edulis-Juniperus osteosperma) community now predominates; Douglas fir are found only in mesic, protected, north-facing areas. Limber pine, Douglas fir, bark, and grasses were the major dietary components in the dung. A springtime diet of birch (Betula) is determined from pollen clumps in dung pellets.  相似文献   

19.
The landscapes of northern New England and adjacent areas of Canada changed greatly between 14,000 and 9000 yr B.P.: deglaciation occurred, sea levels and shorelines shifted, and a vegetational transition from tundra to closed forest took place. Data from 51 14C-dated sites from a range of elevations were used to map ice and sea positions, physiognomic vegetational zones, and the spread of individual tree taxa in the region. A continuum of tundra-woodland-forest passed northeastward and northward without major hesitation or reversal. An increased rate of progression from 11,000 to 10,000 yr B.P. suggests a more rapid warming than in the prior 2000–3000 yr. Elevational gradients controlled the patterns of deglaciation and vegetational change. The earliest spread of tree taxa was via the lowlands of southern Vermont and New Hampshire, and along a coastal corridor in Maine. Only after 12,000 yr B.P. did the taxa spread northward through the rest of the area. Different tree species entered the southern part of the area at different times and continued their spread at different rates. The approximate order of arrival follows: poplars (13,000–12,000 yr B.P. in the south), spruces, paper birch, and jack pine, followed by balsam fir and larch, and possibly ironwood, ash, and elm, and somewhat later by oak, maple, white pine, and finally hemlock (10,000–9000 yr B.P. in the south).  相似文献   

20.
The data obtained from investigation of the Middle and Late Neopleistocene lake sediments in the European Subarctic Region of Russia are reported. Chirva, Rodionovo (Scklov), Sula (Mikulino), and Byzovaya (Leningrad) sediments were subject to palynological analysis and investigation of particle size distribution and mineral composition. The spore–pollen spectra of the Chirva sediments demonstrate two climatic optima: the lower optimum is dominated by the pollen of Pinus sylvestris and broad-leaved species (up to 10%); the upper optimum is dominated by Picea sp. and Pinus sylvestris, while the pollen of Picea sect. Omorica and broad-leaved species are sporadic. The Rodionovo flora is characterized by a more xerophilous composition relative to the Chirva flora and a higher pollen content of pine, birch, wormseed plants, and wormwood. The climatic optimum of the Sula interglacial is distinguished by boreal vegetation, including spruce, birch, and birch–spruce forests with sparse broad-leaved species. The Byzovaya interstadial is marked by seven stages of changes in the vegetation: from tundra and forest-tundra communities to taiga forests with some broad-leaved species. The natural climatic sedimentation conditions in the Middle and Late Neopleistocene interglacial periods are reconstructed. The mineral composition of sediments was largely formed owing to underlying deposits.  相似文献   

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