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Late growing season carbon subsidy in native gymnosperms in a northern temperate forest

journal contribution
posted on 2020-04-27, 00:00 authored by X Li, Chengyuan XuChengyuan Xu, Z Li, J Feng, DT Tissue, KL Griffin
Evergreen tree species that maintain positive carbon balance during the late growing season may subsidize extra carbon in a mixed forest. To test this concept of 'carbon subsidy', leaf gas exchange characteristics and related leaf traits were measured for three gymnosperm evergreen species (Chamaecyparis thyoides, Tsuga canadensis and Pinus strobus) native to the oak-hickory deciduous forest in northeast USA from March (early Spring) to October (late Autumn) in a single year. All three species were photosynthetically active in Autumn. During the Summer-Autumn transition, photosynthetic capacity (Amax) of T. canadensis and P. strobus increased (T-test, P < 0.001) and was maintained in C. thyoides (T-test, P = 0.49), while dark respiration at 20 °C (Rn) and its thermal sensitivity were generally unchanged for all species (one-way ANOVA, P > 0.05). In Autumn, reductions in mitochondrial respiration rate in the daylight (RL) and the ratio of RL to Rn (RL/Rn) were observed in P. strobus (46.3% and 44.0% compared to Summer, respectively). Collectively, these physiological adjustments resulted in higher ratios of photosynthesis to respiration (A/Rnand A/RL) in Autumn for all species. Across season, photosynthetic biochemistry and respiratory variables were not correlated with prevailing growth temperature. Physiological adjustments allowed all three gymnosperm species to maintain positive carbon balance into late Autumn, suggesting that gymnosperm evergreens may benefit from Autumn warming trends relative to deciduous trees that have already lost their leaves. © 2019 The Author(s). Published by Oxford University Press. All rights reserved.

Funding

Other

History

Volume

39

Issue

6

Start Page

971

End Page

982

Number of Pages

12

eISSN

1758-4469

ISSN

0829-318X

Publisher

Oxford University Press

Peer Reviewed

  • Yes

Open Access

  • No

Acceptance Date

2019-02-24

External Author Affiliations

Minzu University of China; Western Sydney University; Columbia University, USA

Era Eligible

  • Yes

Journal

Tree Physiology

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