Correlations of climate and plant ecology to leaf size and shape: potential proxies for the fossil record.

The sizes and shapes (physiognomy) of fossil leaves are widely applied as proxies for paleoclimatic and paleoecological variables. However, significant improvements to leaf-margin analysis, used for nearly a century to reconstruct mean annual temperature (MAT), have been elusive; also, relationships between physiognomy and many leaf ecological variables have not been quantified. Using the recently developed technique of digital leaf physiognomy, correlations of leaf physiognomy to MAT, leaf mass per area, and nitrogen content are quantified for a set of test sites from North and Central America. Many physiognomic variables correlate significantly with MAT, indicating a coordinated, convergent evolutionary response of fewer teeth, smaller tooth area, and lower degree of blade dissection in warmer environments. In addition, tooth area correlates negatively with leaf mass per area and positively with nitrogen content. Multiple linear regressions based on a subset of variables produce more accurate MAT estimates than leaf-margin analysis (standard errors of ±2 vs. ±3°C); improvements are greatest at sites with shallow water tables that are analogous to many fossil sites. The multivariate regressions remain robust even when based on one leaf per species, and the model most applicable to fossils shows no more signal degradation from leaf fragmentation than leaf-margin analysis.

[1]  Sean C. Thomas,et al.  The worldwide leaf economics spectrum , 2004, Nature.

[2]  D. Greenwood,et al.  Paleotemperature Estimation Using Leaf-Margin Analysis: Is Australia Different? , 2004 .

[3]  P. Coley,et al.  Effects of plant growth rate and leaf lifetime on the amount and type of anti-herbivore defense , 2004, Oecologia.

[4]  P. Reich,et al.  A handbook of protocols for standardised and easy measurement of plant functional traits worldwide , 2003 .

[5]  P. Wilf,et al.  Digital Future for Paleoclimate Estimation from Fossil Leaves? Preliminary Results , 2003 .

[6]  Kirk R. Johnson,et al.  Correlated terrestrial and marine evidence for global climate changes before mass extinction at the Cretaceous–Paleogene boundary , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[7]  D. Dilcher,et al.  Warmer paleotemperatures for terrestrial ecosystems , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[8]  M. Westoby,et al.  Leaves at low versus high rainfall: coordination of structure, lifespan and physiology. , 2002, The New phytologist.

[9]  Kirk R. Johnson,et al.  A Tropical Rainforest in Colorado 1.4 Million Years After the Cretaceous-Tertiary Boundary , 2002, Science.

[10]  N. Pitman,et al.  Habitat-related error in estimating temperatures from leaf margins in a humid tropical forest. , 2001, American journal of botany.

[11]  P. Coley,et al.  Insect herbivory, plant defense, and early Cenozoic climate change , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[12]  V. Mosbrugger,et al.  Terrestrial Climate Evolution in Northwest Germany Over the Last 25 Million Years , 2000 .

[13]  K. M. Gregory-Wodzicki,et al.  Relationships between leaf morphology and climate, Bolivia: implications for estimating paleoclimate from fossil floras , 2000, Paleobiology.

[14]  H. Falcon-Lang.  The relationship between leaf longevity and growth ring markedness in modern conifer woods and its implications for palaeoclimatic studies , 2000 .

[15]  Arthur H. Johnson,et al.  POST-DISTURBANCE ABOVEGROUND BIOMASS ACCUMULATION IN GLOBAL SECONDARY FORESTS , 2000 .

[16]  P. Reich,et al.  Convergence and correlations among leaf size and function in seed plants: a comparative test using independent contrasts. , 1999, American journal of botany.

[17]  P. Reich,et al.  Generality of leaf trait relationships: a test across six biomes: Ecology , 1999 .

[18]  S. Manchester,et al.  Estimation of temperature and precipitation from morphological characters of dicotyledonous leaves. , 1998, American journal of botany.

[19]  R. Spicer,et al.  Paleoclimatic significance of Mid-Cretaceous floras from the middle Clarence Valley, New Zealand , 1998 .

[20]  D. Greenwood,et al.  USING FOSSIL LEAVES AS PALEOPRECIPITATION INDICATORS : AN EOCENE EXAMPLE , 1998 .

[21]  J. Parrish.  Interpreting Pre-Quaternary Climate from the Geologic Record: Columbia University Press , 1998 .

[22]  P. Reich,et al.  From tropics to tundra: global convergence in plant functioning. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[23]  P. Wilf.  When are leaves good thermometers? A new case for Leaf Margin Analysis , 1997, Paleobiology.

[24]  P. Ashton.  The tropical rain forest (2nd edn) , 1997 .

[25]  A. Deino,et al.  Test of climate-leaf physiognomy regression models, their application to two Miocene floras from Kenya, and 40Ar/39Ar dating of the Late Miocene Kapturo site , 1996 .

[26]  Biomechanics in fossil plant biology , 1996 .

[27]  D. Greenwood,et al.  Eocene continental climates and latitudinal temperature gradients , 1995 .

[28]  V. Mosbrugger,et al.  Hydrodynamic Modelling Study of Angiosperm Leaf Venation Types , 1995 .

[29]  J. A. Wolfe.  PALEOCLIMATIC ESTIMATES FROM TERTIARY LEAF ASSEMBLAGES , 1995 .

[30]  Palatability of tree foliage to chewing insects: a comparison between a temperate and a tropical site , 1994 .

[31]  D. Greenwood,et al.  Fossils and fossil climate: the case for equable continental interiors in the Eocene , 1993 .

[32]  J. A. Wolfe.  A method of obtaining climatic parameters from leaf assemblages , 1993 .

[33]  P. Reich.  Reconciling apparent discrepancies among studies relating life span, structure and function of leaves in contrasting plant life forms and climates: the blind men and the elephant retold' , 1993 .

[34]  M. Lowman,et al.  Leaf growth dynamics and herbivory in five species of Australian rain-forest canopy trees , 1992 .

[35]  Kevin Padian,et al.  Terrestrial Ecosystems Through Time: Evolutionary Paleoecology of Terrestrial Plants and Animals , 1992 .

[36]  P. Reich,et al.  Leaf Life‐Span in Relation to Leaf, Plant, and Stand Characteristics among Diverse Ecosystems , 1992 .

[37]  R. Spicer.  Physiological characteristics of land plants in relation to environment through time , 1989, Earth and Environmental Science Transactions of the Royal Society of Edinburgh.

[38]  R. Spicer,et al.  Late Cretaceous terrestrial vegetation: A near-polar temperature curve , 1988 .

[39]  J. A. Wolfe,et al.  North American nonmarine climates and vegetation during the Late Cretaceous , 1987 .

[40]  C. Braak.  Canonical Correspondence Analysis: A New Eigenvector Technique for Multivariate Direct Gradient Analysis , 1986 .

[41]  R. Spicer,et al.  Paleobotanical evidence for cool north polar climates in middle Cretaceous (Albian-Cenomanian) time , 1986 .

[42]  F. Stuart Chapin,et al.  Resource Availability and Plant Antiherbivore Defense , 1985, Science.

[43]  F. Stuart Chapin,et al.  Seasonal Changes in Nitrogen and Phosphorus Fractions and Autumn Retranslocation in Evergreen and Deciduous Taiga Trees , 1983 .

[44]  P. Coley,et al.  HERBIVORY AND DEFENSIVE CHARACTERISTICS OF TREE SPECIES IN A LOWLAND TROPICAL FOREST , 1983 .

[45]  J. A. Wolfe.  Temperature parameters of humid to mesic forests of Eastern Asia and relation to forests of other regions of the Northern Hemisphere and Australasia: analysis of temperature data from more than 400 stations in Eastern Asia , 1979 .

[46]  T. Givnish.  On the Adaptive Significance of Leaf Form , 1979 .

[47]  Thomas B. Croat.  Flora of Barro Colorado Island , 1978 .

[48]  O. Loucks,et al.  Optimal leaf size in relation to environment , 1972 .

[49]  S. Vogel.  Convective Cooling at Low Airspeeds and the Shapes of Broad Leaves , 1970 .

[50]  L. Webb.  Environmental Relationships of the Structural Types of Australian Rain Forest Vegetation , 1968 .

[51]  H. D. Macginitie.  Fossil plants of the Florissant beds, Colorado , 1953 .

[52]  E. W. Sinnott,et al.  THE CLIMATIC DISTRIBUTION OF CERTAIN TYPES OF ANGIOSPERM LEAVES , 1916 .

[53]  E. W. Sinnott,et al.  A BOTANICAL INDEX OF CRETACEOUS AND TERTIARY CLIMATES. , 1915, Science.