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The Influence of Ecosystem and Phylogeny on Tropical Tree Crown Size and Shape

Authors :
Theresa Peprah
Benjamin Blonder
Stephen Adu-Bredu
Imma Oliveras
John Seidu
Norma Salinas
Efrain Lopez Choque
Ben Hur Marimon
Yadvinder Malhi
Simone Matias Reis
Alexander Shenkin
Beatriz Schwantes Marimon
Christian Adonteng
Lucio Trujillo Rodriguez
Edith Rosario Clemente Arenas
Miles R. Silman
Gregory P. Asner
Fabio Barbosa Passos
Lisa Patrick Bentley
Brian J. Enquist
Source :
Frontiers in Forests and Global Change, Vol 3 (2020)
Publication Year :
2020
Publisher :
Frontiers Media S.A., 2020.

Abstract

The sizes and shapes of tree crowns are of fundamental importance in ecology, yet understanding the forces that determine them remains elusive. A cardinal question facing ecologists is the degree to which general and non-specific versus ecological and context-dependent processes are responsible for shaping tree crowns. Here, we test this question for the first time across diverse tropical ecosystems. Using trees from 20 plots varying in elevation, precipitation, and ecosystem type (savanna-forest transitions) across the paleo- and neo-tropics, we test the relationship between crown dimensions and tree size. By analyzing these scaling relationships across environmental gradients, biogeographic regions, and phylogenetic distance, we extend Metabolic Scaling Theory (MST) predictions to include how local selective pressures shape variation in crown dimensions. Across all sites, we find strong agreement between mean trends and MST predictions for the scaling of crown size and shape, but large variation around the mean. While MST explained approximately half of the observed variation in tree crown dimensions, we find that local, ecosystem, and phylogenetic predictors account for the half of the residual variation. Crown scaling does not change significantly across regions, but does change across ecosystem types, where savanna tree crowns grow more quickly with tree girth than forest tree crowns. Crowns of legumes were wider and more voluminous than those of other taxa. Thus, while MST can accurately describe the central tendency of tree crown size, local ecological conditions and evolutionary history appear to modify the scaling of crown shape. Importantly, our extension of MST incorporating these differences accounts for the mechanisms driving variation in the scaling of crown dimensions across the tropics. We present allometric equations for the prediction of crown dimensions across tropical ecosystems. These results are critical when scaling the function of individual trees to larger spatial scales or incorporating the size and shape of tree crowns in global biogeochemical models.

Details

Language :
English
Volume :
3
Database :
OpenAIRE
Journal :
Frontiers in Forests and Global Change
Accession number :
edsair.doi.dedup.....ca1ae2135403434d01ac439aea4eeebf