*2.1. Study Area*

The study was conducted in two coniferous forest sites in southern Guangxi Province, China: Guigang (23◦7 N, 109◦28 E) and Qinzhou (22◦2 N, 108◦34 E), as illustrated in Figure 1. The two sites are characterized by a subtropical monsoon climate with an annual rainfall of approximately 1600 mm and an annual average temperature of 21–23 ◦C. The Guigang site was established in a *Pinus massoniana* plantation with a very open understory and few evergreen microphanerophytes (Figure 2a). The *Pinus massoniana* plantation consists predominately of mature forest and had a low tree density of 133 trees/ha. The Qinzhou site was established in a natural forest of *Pinus massoniana*, which is a young forest with various understory species (Figure 2b). It comprises *Pinus massoniana* of mixed ages and has a tree density of 311 trees/ha, which is relatively higher than the Guigang site. The Guigang and Qinzhou sites had 11 and 5 plots, respectively, which were scanned by both the ULS and TLS. A total of sixteen plots were used in this study. The Guigang and Qinzhou plots are referred to as the GG plots and QZ plots, respectively, in the following sections.

**Figure 1.** Map of the two test sites and sixteen sample plots in Guangxi, China: (**a**) Guigang site containing eleven plots and (**b**) Qinzhou site containing five plots analyzed in this study.

(**a**) (**b**)

**Figure 2.** Examples plots in Guigang and Qinzhou sites representing different forest structures: (**a**) GG plot was in mature forest and had a sparse tree density with less understory vegetation, and (**b**) QZ plot was in young forest and had a relatively high tree density representing various understory species.
