Reconstructing Paleoclimate and Paleoecology Using Fossil Leaves

Abstract

Plants are strongly influenced by their surrounding environment, which makes them reliable indicators of climate and ecology. The relationship between climate, ecology, plant traits and the geographic distribution of plants based on their climatic tolerances have been used to develop plant-based proxies for reconstructing paleoclimate and paleoecology. These proxies are some of the most accurate and precise methods for reconstructing the climate and ecology of ancient terrestrial ecosystems and have been applied from the Cretaceous to the Quaternary. Despite their utility, the relationships between plant traits and climate that underlie these methods are confounded by other factors such as leaf lifespan and phylogenetic history. Work focused on better understanding these confounding factors, incorporating the influence of phylogeny and leaf economic spectrum traits into proxies, expanding modern leaf trait-climate and ecology calibration datasets to additional biogeographic areas and climate regimes, and developing automated computer algorithms for measuring leaf traits are important growing research areas that will help considerably improve plant-based paleoclimate and paleoecological proxies.

Isotopic and morphologic proxies for reconstructing light environment and leaf function of fossil leaves: a modern calibration in the Daintree Rainforest, Australia

“…The petiole metric has previously been used to reconstruct an average LMA of ecosystems (Royer et al, 2007) and the ecology and function of plants found in fossil leaf assemblages (Royer et al, 2010; Peppe et al, 2014, 2018). Our observations of LMA were within a range seen across rainforests globally (e.g., 50–120 gm ‐2 ; Poorter et al, 2009).…”

“…The petiole metric may be most useful in predicting LMA across broad environmental gradients (Royer et al, 2007, 2010; Peppe et al, 2018), or when restricted to samples verified as being from the upper canopy crown. The petiole metric does not perform well as a singular predictor of LMA across the full gradient of an intact forest canopy.…”

The influences of environmental change and development on leaf shape in Vitis

“…These relationships between leaf physiognomy and climate in woody dicotyledonous angiosperms have been noted for over 100 years (Bailey and Sinnott, , ) and have been used to develop proxies for reconstructing paleoclimate (e.g., Bailey and Sinnott, , ; Wing and Greenwood, ; Wolfe, ; Wilf, ; Wilf et al., ; Jacobs, , ; Gregory‐Wodzicki, ; Adams et al., ; Peppe et al., ). These patterns of leaf physiognomy and climate have been tested on regional and global scales (e.g., Wolfe, ; Wilf, ; Peppe et al., , ). However, to understand the processes driving changes in leaf physiognomy on a global scale, we must first understand the underlying drivers at individual sites.…”

Paleoclimate and paleoecology of the latest Eocene Florissant flora of Central Colorado, U.S.A.

“…MacGinitie (1953) also argued that the Florissant fossil plants were sourced from both riparian and non-riparian environments by considering the growth habitats of the fossil's NLRs. However, the application of taxon-free approaches, such as leaf mass per area (MA, Royer et al, 2007, see methods below for more details), to Florissant may provide a more reasonable reconstruction of the paleoecology of the flora because of the assumptions, potential biases, and shortcomings of paleoecological reconstructions made using NLR techniques (e.g., the dependency on accurate taxonomic identification, the assumption of unchanged ecological tolerances over time, and the poorly known correlation between leaf economic traits and phylogeny whereby unrelated plants may display convergent evolution of morphological traits adaptive to similar environments; see Peppe et al, 2018 for further discussion).…”