Seasonal changes in vertical canopy structure in a temperate broadleaved forest in Korea

Abstract

Field measurements of vertical canopy structure have been challenging for decades and still important for understanding forest ecosystems. We measured the vertical canopy structure and its seasonal changes in a temperate deciduous forest canopy in Gwangneung, Korea. Time-series measurements of leaf area index (LAI) were collected in 2013 from a five story (4-m vertical intervals) tower. We evaluated crown depth and species composition by height from a vegetation survey. The vertical distribution of leaf and woody area density was described from measurements taken during the leaf-on and leaf-off seasons, and averaged 0.18 and 0.04 m(2) m(-3), respectively. Three strata were characterized: (1) the dense upper crowns with large trees (> 16-m) of Quercus serrata, in which 29.3 % of the plant materials were distributed; (2) abundant foliage dominated by Carpinus laxiflora at about 16-m (40.8 %); and (3) a diverse and well-developed understory vegetation at about 4-m (15.5 %), consisting of C. laxiflora, Carnipus cordata, and Styrax japonica communities. Per-layer phenology of each species was successfully illustrated by the drastic increase in LAI during the leaf-out season [days of the year (DOY) 110-140], the full-leaved stage LAI of 3.4 +/- A 0.9 m(2) m(-2) (mean +/- 1 standard deviation), and a decrease during the leaf-fall season (DOY 280-320). The seasonal variation in gap fractions reflected different light conditions varying with canopy height. This type of vertical profile archive is valuable not only for comparing the structure of various forests but also for monitoring changes in this ecosystem in the future.