Canopy structure and understory light characteristics of a natural Quercus aliena var. acuteserrata forest in China northwest: Influence of different forest management methods

Abstract

Close-to-nature forest management (CNFM), structure-based forest management (SBFM), and secondary forest comprehensive silviculture (SFCS) are three forest management methods that have been promoted in China. Unfortunately, changes to the canopy structure and understory light characteristics after forest management remain unclear. We compared the canopy structure and light characteristics of a natural Quercus aliena var. acuteserrata forest under the four management methods of CNFM, SBFM, SFCS and unmanaged control (CK) after four years of using the WinScanopy instrument. The results suggest that (1) the leaf area index (LAI) values in the CNFM and SBFM were higher than that in the CK, the mean leaf angle (MLA) value in the SBFM was significantly lower than that in the CK. (2) The values of total under radiant energy (TU) and directed radiant energy (Dir) in the SFCS were significantly higher than that in the CK, while the values of diffused radiant energy (Dif) in the CNFM and SBFM were significantly lower than that in the CK. The extinction coefficient (EC) value in three forest management measure was significantly lower than that in the CK. (3) The canopy structure was sensitive to changes in tree crowding, and the light characteristics were sensitive to changes in forest layer numbers, LAI and CO, which explained 81.19% and 94.88% of the total variations in the canopy structure and light characteristics, respectively. Thus, CNFM and SBFM altered the canopy structure, which may be attributed to the LAI that was influenced by tree crowding, and the three forest treatments altered the understory light environment, which may be influenced mainly by the canopy structure. CNFM and SBFM increased the leaf area index of the stand and improved the understory light environment in a natural Quercus aliena var. acuteserrata forest.