Distribution of evapotranspiration components along vertical layers and their controls in dry days of larch plantation in the Liupan Mountains of northwest China

• Published in: Agricultural and forest meteorology Vol. 358
• Main Authors: Yu, Songping, Liu, Zebin, Guo, Jianbin, Wang, Yanhui, Yu, Pengtao, Xu, Lihong, Wang, Yubing, Chao, Yang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.11.2024
• Subjects: Environmental conditions; Multi–factor coupling models; Partitioning of evapotranspiration; Vertical structure; Vertical structure; Multi–factor coupling models; Partitioning of evapotranspiration; Environmental conditions
• ISSN: 0168-1923
• DOI: 10.1016/j.agrformet.2024.110265

•Quantification of vertical distribution of evapotranspiration (ETf) components along forest layers.•A systematic evapotranspiration model reflecting the impacts of forest layer structure.•Higher accuracy and local applicability of new evapotranspiration model compared to conventional model. Precise quantification of forest evapotranspiration (ETf) including transpiration from tree (Tt), shrub (Ts), and herb (Th) layers, as well as evaporation from litter (El) and soil (Es) layers, and elucidating their responses to environmental conditions and stand structures are crucial for forest water management in water-limited forests. In this study, we observed the Tt, Ts, Th, El, and Es, reference evapotranspiration (ETo), soil volumetric water content (SWC), litter water content (LWC), leaf area index (LAI) in tree, shrub, and herb layers, and canopy shade (Ksc) from tree layer of the Larix principis-rupprechtii plantation during the dry days from May to October of 2021 and 2022 to elucidate the distribution of evapotranspiration along vertical layers and their environmental and structural determinants. The results indicated that the contributions of Tt, Ts, Th, El, and Es to ETf during the dry days in 2021 (2022) were 42.1 % (44.7 %), 9.2 % (8.1 %), 8.2 % (8.6 %), 15.0 % (13.1 %), and 25.5 % (25.5 %), respectively. Although Tt and Ts demonstrated quadratic relationships with ETo, Th, El, and Es exhibited linear relationships. All ETcs demonstrated a saturated exponential relationship with either SWC or LWC. Furthermore, Tt, Ts, and Th showed a saturated exponential relationship with their respective LAI, whereas El and Es exhibited a cubic relationship with LAI in tree layers. All understory ETcs (Ts, Th, El, and Es) decreased exponentially with the Ksc. The multi-factor models of evapotranspiration component (ETc) from different vertical layers, which coupled the impacts of environmental conditions and vertical structure, were developed, and provided superior accuracy (R2 = 0.78–0.88, NSE = 0.78–0.86, RSME = 0.03–0.16). Such insights deepened the understanding of vertical structural distribution and multi-factor responses of ETcs in forest ecosystems and hold the potential to inform and optimise forest water management strategies. [Display omitted]