skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis

Abstract

Tropical tree species have evolved under very narrow temperature ranges compared to temperate forest species. Studies suggest that tropical trees may be more vulnerable to continued warming compared to temperate species, as tropical trees have shown declines in growth and photosynthesis at elevated temperatures. However, regional and global vegetation models lack the data needed to accurately represent such physiological responses to increased temperatures, especially for tropical forests. To address this need, we compared instantaneous photosynthetic temperature responses of mature canopy foliage, leaf temperatures, and air temperatures across vertical canopy gradients in three forest types: tropical wet, tropical moist, and temperate deciduous. Temperatures at which maximum photosynthesis occurred were greater in the tropical forests canopies than the temperate canopy (30 ± 0.3 °C vs. 27 ± 0.4 °C). However, contrary to expectations that tropical species would be functioning closer to threshold temperatures, photosynthetic temperature optima was exceeded by maximum daily leaf temperatures, resulting in sub-optimal rates of carbon assimilation for much of the day, especially in upper canopy foliage (>10 m). If trees are unable to thermally acclimate to projected elevated temperatures, these forests may shift from net carbon sinks to sources, with potentially dire implications to climate feedbacks and forestmore » community composition.« less

Authors:
 [1];  [2];  [3];  [1]
  1. Michigan Technological Univ., Houghton, MI (United States)
  2. Southwest Biological Science Center (SBSC), Moab, UT (United States)
  3. USDA Forest Service, Río Piedras, PR (United States). International Inst. of Tropical Forestry
Publication Date:
Research Org.:
Michigan Technological Univ., Houghton, MI (United States); Southwest Biological Science Center (SBSC), Moab, UT (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1510297
Grant/Contract Number:  
SC0012000; SC0011806
Resource Type:
Accepted Manuscript
Journal Name:
Forests
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 1999-4907
Publisher:
MDPI
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; forest canopies; tropical forests; photosynthesis; temperature; climate change

Citation Formats

Mau, Alida, Reed, Sasha, Wood, Tana, and Cavaleri, Molly. Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis. United States: N. p., 2018. Web. doi:10.3390/f9010047.
Mau, Alida, Reed, Sasha, Wood, Tana, & Cavaleri, Molly. Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis. United States. doi:10.3390/f9010047.
Mau, Alida, Reed, Sasha, Wood, Tana, and Cavaleri, Molly. Mon . "Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis". United States. doi:10.3390/f9010047. https://www.osti.gov/servlets/purl/1510297.
@article{osti_1510297,
title = {Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis},
author = {Mau, Alida and Reed, Sasha and Wood, Tana and Cavaleri, Molly},
abstractNote = {Tropical tree species have evolved under very narrow temperature ranges compared to temperate forest species. Studies suggest that tropical trees may be more vulnerable to continued warming compared to temperate species, as tropical trees have shown declines in growth and photosynthesis at elevated temperatures. However, regional and global vegetation models lack the data needed to accurately represent such physiological responses to increased temperatures, especially for tropical forests. To address this need, we compared instantaneous photosynthetic temperature responses of mature canopy foliage, leaf temperatures, and air temperatures across vertical canopy gradients in three forest types: tropical wet, tropical moist, and temperate deciduous. Temperatures at which maximum photosynthesis occurred were greater in the tropical forests canopies than the temperate canopy (30 ± 0.3 °C vs. 27 ± 0.4 °C). However, contrary to expectations that tropical species would be functioning closer to threshold temperatures, photosynthetic temperature optima was exceeded by maximum daily leaf temperatures, resulting in sub-optimal rates of carbon assimilation for much of the day, especially in upper canopy foliage (>10 m). If trees are unable to thermally acclimate to projected elevated temperatures, these forests may shift from net carbon sinks to sources, with potentially dire implications to climate feedbacks and forest community composition.},
doi = {10.3390/f9010047},
journal = {Forests},
number = 1,
volume = 9,
place = {United States},
year = {2018},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share: