Climatic envelope of evergreen sclerophyllous oaks and their present distribution in the eastern Himalaya and Hengduan Mountains

Evergreen sclerophyllous oaks （the E.S. oaks, Quercus section Heterobalanus） are the dominant species of the local ecosystem in the eastern Himalaya and the Hengduan Mountains, southwest China. In this study, we document the climatic envelope of the seven E.S. oak species and examine the relationships between climate and their distribution. This was done using a principal components analysis （PCA） and multiple regression analysis （MRA） of nine climatic indices. The main climatic envelope of the E.S. oaks were： mean temperature of the warmest month （MTW）= 12.0-19.5℃, warmth index （WI） = 33.2-88.9℃ month, annual biotemperature （BT）=-6.9- -0.3 ℃, coldness index （CI）=-30.4- -10.1 ℃ month, mean temperature of the coldest month （MTC）=-3.7-3.0℃ and annual precipitation （AP）=701-897 mm at the lower limits; and MTW=8.3-16.1℃, WI=15.7-59.1℃ month, BT=3.6-8.9℃, CI=-55.4-19.3℃ month, MTC=8.3-16.1 ℃ and AP=610-811 mm at the upper limits. The climatic range of the E.S. oaks is wide and includes two climatic zones, the cool-temperature zone and the subpolar zone. The PCA and MRA results suggest that the thermal climate plays a major role and precipitation plays a secondary role in controlling the large-scale distribution of the E.S. oaks, except Quercus monimotricha. In thermal regimes, BT and/or MTW are most important for both lower and upper limits of the E.S. oaks. Furthermore, our results indicate that the upper distribution limits of the E.S. oaks are less determined by low temperatures and their duration （CI） than by other factors.

Leaf fossils of Sabalites(Arecaceae)from the Oligocene of northern Vietnam and their paleoclimatic implications

Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast Asia.Palms(Arecaceae)are a diverse family of typical thermophilous plants with a relatively low tolerance for freezing.In this study,we describe well-preserved fossil palm leaves from the Oligocene Dong Ho Formation of Hoanh Bo Basin,northern Vietnam.Characters of the fossil leaves,such as a fan-shaped costapalmate lamina,an unarmed petiole,a costa slightly enlarged at the base that then tapers distally into the blade,and well-preserved amphistomatic leaves with cuticles,suggest that they represent a new fossil species,which we herein designate Sabalites colaniae A.Song,T.Su,T.V.Do et Z.K.Zhou sp.nov.Together with other paleontological and palaeoclimatic evidence,we conclude that a warm climate prevailed in northern Vietnam and nearby areas during the Oligocene.

Late Pliocene diversity and distribution of Drynaria(Polypodiaceae) in western Yunnan explained by forest vegetation and humid climates

The palaeodiversity of flowering plants in Yunnan has been extensively interpreted from both a molecular and fossil perspective. However, for cryptogamic plants such as ferns, the palaeodiversity remains poorly known. In this study, we describe a new ferny fossil taxon, Drynaria lanpingensis sp. nov. Huang,Su et Zhou(Polypodiaceae), from the late Pliocene of northwestern Yunnan based on fragmentary frond and pinna with in situ spores. The frond is pinnatifid and the pinnae are entirely margined. The sori are arranged in one row on each side of the primary vein. The spores have a semicircular to bean-shaped equatorial view and a tuberculate surface. Taken together with previously described fossils, there are now representatives of three known fossil taxa of Drynaria from the late Pliocene of western Yunnan.These finds suggest that Drynaria diversity was considerable in the region at that time. As Drynaria is a shade-tolerant plant, growing preferably in wet conditions in the understory of forests, its extensive existence may indicate forest vegetation and humid climates in western Yunnan during the late Pliocene.This is in line with results from floristic investigations and palaeoclimatic reconstructions based on fossil floras.

Fossil fruits of Firmiana and Tilia from the middle Miocene of South Korea and the efficacy of the Bering land bridge for the migration of mesothermal plants

Determining whether the high-latitude Bering land bridge(BLB)was ecologically suitable for the migration of mesothermal plants is significant for Holarctic phytogeographic inferences.Paleobotanical studies provide a critical source of data on the latitudinal positions of different plant lineages at different times,permitting assessment of the efficacy of the BLB for migration.Here we report exceptionally preserved fossils of Firmiana and Tilia endochrysea from the middle Miocene of South Korea.This represents a new reliable record of Firmiana and the first discovery of the T.endochrysea lineage in the fossil record of Asia.The occurrence of these fossils in South Korea indicates that the two lineages had a distribution that extended much farther north during the middle Miocene,but they were still geographically remote from the BLB.In light of the broader fossil record of Asia,our study shows that,in the middle Miocene,some mesothermal plants apparently inhabited the territory adjacent to the BLB and thus they were possibly capable of utilizing the BLB as a migratory corridor.Some other mesothermal plants,such as Firmiana and the T.endochrysea lineages,however,are restricted to more southern regions relative to the BLB based on current fossil evidence.These lineages may have been ecologically unable to traverse the BLB,which raises questions about the efficacy of the BLB as a universal exchange route for mesothermal plants between Asia and North America during the middle Miocene.

New fossil seeds of Eurya （Theaceae） from East Asia and their paleobiogeographic implications

Eurya has an excellent fossil record in Europe,but it has only a few fossil occurrences in East Asia though this vast area houses the highest modern diversity of the genus.In this study,three-dimensionally preserved fossil seeds of Euiya stigmosa(Ludwig) Mai from the late Pliocene of northwestern Yunnan,southwestern China are described.The seeds are compressed and flattened,slightly campylotropous,and nearly circular to slightly angular in shape.The surface of the seeds is sculptured by a distinctive foveolate pattern,consisting of funnel-shaped and finely pitted cells.Each seed valve contains a reniform or horseshoe-shaped embryo cavity,a characteristic condyle structure and an internal raphe.These fossil seeds represent one of the few fossil records of Eurya in East Asia.This new finding therefore largely extends the distributional ranges of Eurya during Neogene.Fossil records summarized here show that Euiya persisted in Europe until the early Pleistocene,but disappeared thereafter.The genus might have first appeared in East Asia no later than the late Oligocene,and dispersed widely in regions such as Japan,Nepal,and southwestern China.

Higher palaeoelevation in the Baoshan Basin:Implications for landscape evolution at the southeastern margin of the Tibetan Plateau

Surface uplift at the southeastern margin of the Tibetan Plateau has been widely studied,but more palaeoaltimetry data are required to better understand the elevation history of this geologically complex region.In this study,fossil leaves of Abies(Pinaceae),a cool-temperate element,recovered from the latest MioceneePliocene Yangyi Formation of the southern Baoshan Basin,were used as a proxy to estimate the local palaeoelevation.Based on the regional modern altitude range(2100e4280 m)of the genus as well as regional temperature discrepancy(1.5℃)between the past and present,the palaeoelevation of the study area was calculated to be>2360 m above sea level as compared to 1670 m at present.Our result suggests that the southern Baoshan Basin experienced pronounced uplift prior to the time of fossil deposition,probably as a result of crustal shortening and thickening of the northern Baoshan Terrane during the EoceneeOligocene.We infer that surface growth in areas south of the Dali Basin may have been greater than previously interpreted,and that a widespread plateau or plateau patches higher than 2000 m probably extended southwards into at least the Baoshan Basin by the latest MioceneePliocene.We also infer that the elevation of the southern Baoshan Basin has decreased by at least 690 m since then,in contrast to most other scenarios in which the elevation of the southeastern margin of the Tibetan Plateau has increased or remained close to modern levels since the late Miocene.The major cause of the inferred altitude decline is likely tectonic deformation.As a transtensional graben basin,the Baoshan Basin has experienced pull-apart and base-fall movement since the late Miocene,which would reduce the altitude of its southern part located on the hanging wall.Surface erosion associated with the increased summer rainfall might also have played a role especially in reducing the local relief,although its contribution can be limited.Our study provides one of the few palaeoelevation estimates from areas south of the Dali Basin and an example of past elevation loss at the southeastern margin of the Tibetan Plateau,thus shedding important light on the landscape evolution of this region.

Wildfire associated with a deciduous broadleaved forest from the Neogene Baoshan Basin at the southeastern margin of the Tibetan Plateau

Wildfire bears a close relationship with vegetation as its fuel source.The southeastern margin of the Tibetan Plateau witnesses frequent wildfires among various types of vegetation,whereas such wide in-teractions between wildfire and vegetation remain poorly studied from geological times.In this study,we reported a local fire using sedimentary macroscopic charcoals from the latest Miocene to early Pliocene of the Baoshan Basin in this region,and then inferred the local vegetation at the time of the fire event based chiefly on the coexistent fruit and seed fossil assemblage.Our taxonomic results show that the charcoal assemblage is probably dominated by broadleaved plants and the fruit and seed fossil assemblage is apparently dominated by Salix(Salicaceae)followed by Sambucus(Adoxaceae),suggesting a deciduous broadleaved forest in which the fire likely occurred.Under a seasonally dry climate associated with the Asian monsoon,this type of vegetation might be prone to natural fire,because in the wet rainy season the plants grew well to accumulate biofuel and in the dry season abundant ground litter resulting from leaf decay would be desiccated to become highly flammable.Due to the fire-tolerant habit of Salix as the dominant plant,the forest might be in return adapted to the fire event or even more fires that potentially followed.All these may suggest a close relationship between the fire event and the reconstructed vegetation.Our finding documents a new type of wildfire—vegetation interaction,namely the interaction between wildfire and deciduous broadleaved forest,from the geological past at the southeastern margin of the Tibetan Plateau.It therefore sheds new light on the wildfire history coupling vegetation change in the region.

Lake geochemistry reveals marked environmental change in Southwest China during the Mid Miocene Climatic Optimum

中间中新世的气候的最佳(MMCO；~ 15-17 ? 妈) 是标点的短期的气候的温暖的事件之一新生代长期的冷却趋势。因为有这个事件的很少的陆上的记录，大多数我们的理解来自海洋的核心。在这份报告，我们首先介绍修订标明日期的新 palaeomagnetic 数据我们的 400 ? 在 Wenshan (云南) 的 m 厚的湖的节，以前想了晚中新世。这些新数据建议老年， ca。15.2-16.5 ? 妈，与 MMCO 与一致。我们测量了 13 体积有机物上的 C (13 C 器官的碳(TOC ) ，全部的氮(TN ) 和在高度的 C/N 比率取样的 org ), 总数分辨率：(1 ) 重建在湖集水区域的 palaeoenvironmental 变化，并且(2 ) 推断为这些变化负责的机制。我们的结果证明所有四个 geochemical 参数证明一个强壮的环境变化发生在节的中间附近，立即在在 15.97 点的 C5Cn/C5Br 地磁气的颠倒和早 / 中间中新世的边界以后 ? 妈。我们建议环境移动可能由于在气候的一个变化的联合，它变得更凉爽，和在有机物在湖以内骑车的一个变化。这研究提供新卓见进 MMCO 并且证明尽管 MMCO 通常是一个温暖的事件，它也是气候的不稳定性和突然的环境变化的一倍。