Combined LM and SEM study of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin, Austria: part IV. Magnoliophyta 2 – Fagales to Rosales

An ongoing investigation of the middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin continues to show that it contains an extremely rich assemblage of angiosperm taxa. The Fagales to Rosales pollen record documented here contains 34 different taxa belonging to the Betulaceae (Alnus, Betula, Carpinus, Corylus, Ostrya), Fagaceae (Castanea, Fagus, Quercus Groups Cerris, Ilex, Cyclobalanopsis, Quercus/Lobatae), Juglandaceae (Engelhardioideae, Carya, Juglans, Pterocarya), Myricaceae (Morrella vel Myrica), Cannabaceae (Celtis), Elaeagnaceae (Elaeagnus), Rhamnaceae, Rosaceae (Prunus) and Ulmaceae (Cedrelospermum, Ulmus, Zelkova). Two of the pollen types represent extinct genera, Trigonobalanopsis and Cedrelospermum, and are also reported for the first time from the Lavanttal Basin along with pollen of Rhamnaceae and Prunus. The different types of Quercus pollen are now affiliated with Groups Cerris, Cyclobalanopsis, Ilex and Quercus/Lobatae based on sculpturing elements observed using scanning electron microscopy (SEM). Köppen signatures of potential modern analogues of the fossil Fagales and Rosales suggest a subtropical (Cfa, Cwa) climate at lower elevation and subsequent subtropical to temperate climate with altitudinal succession (Cfa → Cfb/Dfa→ Dfb; Cwa → Cwb → Dwb) in the Lavanttal area during accumulation of the palynoflora. Most of the fossil taxa have potential modern analogues that can be grouped as nemoral and/or merido-nemoral vegetation elements, and the diversity of Fagales indicates a varying landscape with a high variety of niches.

针对拉万塔尔盆地（Lavanttal Basin）中中新世（萨尔马特期，Sarmatian）孢粉植物群（palynoflora）的持续研究表明，该区域产出极为丰富的被子植物类群组合。本次记录的壳斗目（Fagales）至蔷薇目（Rosales）花粉序列共包含34个不同类群，隶属于桦木科（Betulaceae，含桤木属Alnus、桦木属Betula、鹅耳枥属Carpinus、榛属Corylus、铁木属Ostrya）、壳斗科（Fagaceae，含栗属Castanea、水青冈属Fagus、栎属Quercus的Cerris组、Ilex组、Cyclobalanopsis组、Quercus/Lobatae组）、胡桃科（Juglandaceae，含黄杞亚科Engelhardioideae、山核桃属Carya、胡桃属Juglans、枫杨属Pterocarya）、杨梅科（Myricaceae，含Morrella 等同 Myrica）、大麻科（Cannabaceae，含朴属Celtis）、胡颓子科（Elaeagnaceae，含胡颓子属Elaeagnus）、鼠李科（Rhamnaceae）、蔷薇科（Rosaceae，含李属Prunus）以及榆科（Ulmaceae，含椿榆属Cedrelospermum、榆属Ulmus、榉属Zelkova）。其中两类花粉类型分别代表已灭绝的三角果栎属（Trigonobalanopsis）和椿榆属（Cedrelospermum），本次研究同时首次在拉万塔尔盆地报道了鼠李科与李属的花粉化石。基于扫描电子显微镜（SEM）观察到的纹饰特征，本次研究将不同类型的栎属花粉归属于Cerris组、Cyclobalanopsis组、Ilex组以及Quercus/Lobatae组。通过对壳斗目与蔷薇目化石类群的现代相似类群进行柯本气候（Köppen）特征分析，结果表明拉万塔尔盆地在孢粉沉积时期，低海拔区域为亚热带气候（Cfa、Cwa），整体呈现随海拔升高由亚热带向温带气候过渡的垂直气候带分布特征（Cfa → Cfb/Dfa→ Dfb；Cwa → Cwb → Dwb）。多数化石类群存在对应的现代相似类群，可归为温带森林和/或暖温带森林植被组分；壳斗目的类群多样性则反映出当时研究区域存在生境类型多样的复杂景观。