关键词: 关键词 针阔叶混交林, 能量通量, 潜热通量, 显热通量, 能量流动

Abstract: Aims Under the background of global climate change, this study investigated the dynamic characteristics of energy fluxes in Jinyun Mountain's coniferous-broadleaf mixed forest across different temporal scales and their responses to environmental factors. Methods We selected the mixed coniferous and broad-leaved forests in Jinyun Mountains as the study area, and analyzed the long time series flux data of the mixed coniferous and broad-leaved forests in Jinyun Mountains for the years 2020, 2021, and 2023 (data for 2022 are missing) using correlation factor analysis and structural equation modeling based on the data measured by eddy correlation technique. Important findings (1) At the diurnal scale, net radiation (Rn), sensible heat flux (H), and latent heat flux (LE) exhibited unimodal trends, with their peak values occurring at 14:00 local time, and approaching near-zero values after 19:00. In contrast, soil heat flux (G) displayed a bimodal pattern, reaching its daily minimum prior to sunrise and attaining its daily maximum at 14:00 local time. (2) At the monthly scale, the influence of Rn on energy fluxes increased from April, reached its maximum in July and August, then gradually decreased. The influence of Gs on LE followed the same trend. (3) At the growing season scale, Rn was the primary influencing factor for energy flux variations. Correlation factor analysis indicated that canopy conductance (Gs) had a slight limiting effect on H but a significant limiting effect on LE. However, the plant water balance mechanism exerted the strongest influence. (4) The annual mean Bowen ratios (β) for the three years were 0.69, 0.63, and 0.76, respectively. (5) Influenced by extreme drought, the sensible heat flux at the annual scale exhibited a bimodal trend. This study analyzed the characteristics and influencing factors of energy fluxes in the Jinyun Mountain coniferous-broadleaf mixed forests, revealing the dynamic processes of energy fluxes, quantifying the impacts of environmental factors, and providing a scientific basis for assessing the response of subtropical forest ecosystems to climate change and forest conservation.

Key words: Key words Coniferous and broad-leaved mixed forest, energy flux, Latent heat flux, Sensible heat flux, Energy flows