Leaf habit of Late PermianGlossopteristrees from high-palaeolatitude forests

Abstract

Abstract:The leaf longevity of trees, deciduous or evergreen, plays an important role in climate feedbacks and plant ecology. in modern forests of the high latitudes, evergreen trees dominate; however, the fossil record indicates that deciduous vegetation dominated during some previous warm intervals. We show, through an integration of palaeobotanical techniques and isotope geochemistry of trees in one of the earliest polar forests (Late Permian, c. 260 Ma, Antarctica), that the arborescent glossopterid taxa were both deciduous and evergreen, with a greater abundance of evergreen trees occurring in the studied forests. These new findings suggest the possibility that deciduousness was a plastic trait in ancient polar plants, and that deciduous plants, migrating poleward from lower latitudes, were probably better adapted to high-disturbance areas in environments that were light-limited.

Highly productive polar forests from the Permian of Antarctica

“…16 woody material that is preserved in the Buckley Formation, and the presence at Lamping Peak of Glossopteris as the only leaf type and of Vertebraria, we follow previous workers (e.g., Gulbranson et al, 2012;Gulbranson et al, 2014) and interpret Lamping Peak forests to have been composed of trees bearing Glossopteris leaves.…”

“…5 augmenting paleoclimate information and providing a wealth of information about the floristic composition and plant anatomy (e.g., Taylor et al, 1992;Cúneo et al, 1993;Pigg and Taylor, 1993;Taylor et al, 2000;Taylor and Ryberg, 2007;Decombeix, 2010;Ryberg and Taylor, 2013;Gulbranson et al, 2014).…”

“…Picciotto are covered with plant material, 100% of the non-stem identifiable material consists of Glossopteris leaves; Vertebraria, the distinctive root structures of Glossopteris also occur in both horizons (Cúneo et al, 1993). The profuse leaf covers on bedding planes have been interpreted as leaf mats that accumulated during leaf drop, implying a deciduous habit for Glossopteris (Cúneo et al, 1993;Taylor et al, 2000) however, Gulbranson et al (2014) recently suggested that glossopterids in the Beardmore area included both deciduous and evergreen habits.…”

“…The Permian sequence consists of: 1) glacigenic, primarily glacial marine and glacial lacustrine deposits recording Gondwanan glaciation (Pagoda Formation, Isbell et al, 1997;; 2) shale and interbedded sandstone deposited in a large post-glacial lake or series of lakes filled by deltaic sediments (Mackellar Formation and lowermost Fairchild Formation, Miller, M.F., et al, 2010); 3) crossbedded sandstone lacking plant fossils deposited in braided stream channels (bulk of Fairchild Formation, Barrett et al, 1986); and sandstone, siltstone, shale and coal deposited in braided stream systems (Buckley Formation, Isbell, 1990;Isbell et al, 1997;Gulbranson et al, 2012Gulbranson et al, , 2014. The amount of plant material and the thickness and extent of coal increases upward within the Buckley Formation.…”

A Permian nurse log and evidence for facilitation in high-latitudeGlossopterisforests

“…During the Permian, the warming of the global climate from icehouse to extreme hothouse conditions allowed trees to colonize high latitudes and establish forests well beyond the polar circle (Taylor et al 2000; Cantrill & Poole 2012). Fossils from these regions yield insights into the diversity and biology of the trees growing in these ecosystems with no modern analogue, that is warm polar forests with a strongly seasonal light regime (Creber 1990; Francis 1994; Taylor & Ryberg 2007; Gulbranson et al 2014; Slater et al 2015; Miller et al 2016). In the Late Permian, the high‐latitude forests of the Southern Hemisphere were largely dominated by trees belonging to an extinct order of seed plants, the Glossopteridales (Cúneo et al 1993; Anderson et al 1999; Taylor et al 2009).…”