In:
American Journal of Botany, Wiley, Vol. 108, No. 12 ( 2021-12), p. 2435-2451
Abstract:
Reconstructing the light environment and architecture of the plant canopy from the fossil record requires the use of proxies, such as those derived from cell wall undulation, cell size, and carbon isotopes. All approaches assume that plant taxa will respond predictably to changes in light environments. However, most species‐level studies looking at cell wall undulation only consider “sun” or “shade” leaves; therefore, we need a fully quantitative taxon‐specific method. Methods We quantified the response of cell wall undulation, cell size, and carbon isotopes of Platanus occidentalis using two experimental setups: (1) two growth chambers at low and high light and (2) a series of outdoor growth experiments using green and black shade cloth at different densities. We then developed and applied a proxy for daily light integral (DLI) to fossil Platanites leaves from two early Paleocene floras from the San Juan Basin in New Mexico. Results All traits responded to light environment. Cell wall undulation was the most useful trait for reconstructing DLI in the geological record. Median reconstructed DLI from early Paleocene leaves was ~44 mol m −2 d −1 , with values from 28 to 54 mol m −2 d −1 . Conclusions Cell wall undulation of P. occidentalis is a robust, quantifiable measurement of light environment that can be used to reconstruct the paleo‐light environment from fossil leaves. The distribution of high DLI values from fossil leaves may provide information on canopy architecture; indicating that either (1) most of the canopy mass is within the upper portion of the crown or (2) leaves exposed to more sunlight are preferentially preserved.
Type of Medium:
Online Resource
ISSN:
0002-9122
,
1537-2197
DOI:
10.1002/ajb2.v108.12
Language:
English
Publisher:
Wiley
Publication Date:
2021
detail.hit.zdb_id:
2053581-8
SSG:
12
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