Seasonal changes in hydraulic functions of eight temperate tree species: divergent responses to freeze-thaw cycles in spring and autumn

Zhimin Li; Dandan Luo; Muhammed Mustapha Ibrahim; Xianzhen Luo; Rufang Deng; Chuankuan Wang; Enqing Hou

doi:10.1093/treephys/tpae132

Seasonal changes in hydraulic functions of eight temperate tree species: divergent responses to freeze-thaw cycles in spring and autumn

Tree Physiol. 2024 Oct 12:tpae132. doi: 10.1093/treephys/tpae132. Online ahead of print.

Authors

Zhimin Li^{1

2

3}, Dandan Luo^{2

3}, Muhammed Mustapha Ibrahim¹, Xianzhen Luo¹, Rufang Deng¹, Chuankuan Wang^{2

3}, Enqing Hou¹

Affiliations

¹ Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
² Center for Ecological Research, Northeast Forestry University, 26 Hexing Road, Harbin, 150040, China.
³ Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University, 26 Hexing Road, Harbin, 150040, China.

PMID: 39394964
DOI: 10.1093/treephys/tpae132

Abstract

Freeze-thaw cycles (FTCs) are the major seasonal environment stress in the temperate and boreal forests, which induces hydraulic dysfunction and limits tree growth and distribution. There are two types of FTCs in the field: FTCs with increasing temperature from winter to spring (spring FTCs); and FTCs with decreasing temperature from autumn to winter (autumn FTCs). While previous studies have evaluated the hydraulic function during the growing season, its seasonal changes and how it adapts to different types of FTCs remain unverified. To fill this knowledge gap, the eight tree species from three wood types (ring- and diffuse-porous, tracheid) were selected in a temperate forest undergoing seasonal FTCs. We measured the branch hydraulic traits in spring, summer, autumn, and early, middle, and late winter. Ring-porous trees always showed low native hydraulic conductance (Kbranch), and high percentage loss of maximum Kbranch (PLCB) and water potential that loss of 50% maximum Kbranch (P50B) in non-growing seasons (except summer). Kbranch decreased, and PLCB and P50B increased in diffuse-porous trees after several spring FTCs. In tracheid trees, Kbranch decreased after spring FTCs while the P50B did not change. All sampled trees gradually recovered their hydraulic functions from spring to summer. Kbranch, PLCB, and P50B of diffuse-porous and tracheid trees were relatively constant after autumn FTCs, indicating almost no effect of autumn FTCs on hydraulic functions. These results suggested that hydraulic functions of temperate trees showed significant seasonal changes, and spring FTCs induced more hydraulic damage (except ring-porous trees) than autumn FTCs, which should be determined by the number of FTCs and trees' vitality before FTCs. These findings advance our understanding of seasonal changes in hydraulic functions and how they cope with different types of freeze-thaw cycles in temperate forests.

Keywords: Branch; Freezing stress; Hydraulic traits; Temperate forest; Winter.