Long‐term canopy dynamics in a large area of temperate old‐growth beech (Fagus crenata) forest: analysis by aerial photographs and digital elevation models

Abstract

Summary1 Long-term canopy dynamics in a large area of temperate old-growth beech forest in the Daisen Forest Reserve, south-western Japan (11.56 ha studied over 43 years), were investigated using digital elevation models (DEMs) of the canopy surface, constructed from aerial photographs taken in the growing season (i.e. with foliage) in 1958, 1978, 1992 and 2001. A ground surface DEM at the same resolution (a 2.5 × 2.5 m grid) was constructed using aerial photographs taken when foliage was absent (winter 2002). Canopy height data were obtained by calculating differences in elevation between the canopy and the ground surface, and a canopy height profile was constructed. 2 Topographic data for a 4-ha plot, located within the 11.56-ha area, were obtained via a ground survey and used to validate the ground surface DEM derived from aerial photographs. 3 Canopy height class distributions changed significantly over the 43 years. The total number of gaps, defined as areas where canopy height was ≤ 15 m, decreased but total gap area increased over time. Total gap area in 2001 was twice that of 1958. The density of gaps decreased as gap size increased. 4 Gap formation rates increased from 0.47% year − 1 (1958-78) to 1.30% year − 1 (1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001), with a mean of 0.77% year − 1 , and substantially exceeded closure rates, which fluctuated from 0.28% year − 1 (1958-78) to 0.54% year − 1 , with a mean of 0.39% year − 1 . Gaps generally expanded and became connected to each other. 5 Temporal variation in gap formation and closure might be correlated with the frequency and severity of typhoon disturbances but, if the observed trends continue, this old-growth beech stand may become an open stand. The long-term dynamics of this forest type appear to be far from equilibrium.

Lack of natural control mechanisms increases wildlife–forestry conflict in managed temperate European forest systems

“…In contrast, fine-scale, gap-phase dynamics is a characteristic feature in oldgrowth temperate forest (Faliński 1986;Bobiec et al 2000;Kenderes et al 2008). Gap formation typically occurs of one single tree falling down and creating relatively small gaps, with mean gap sizes ranging between 40 to 190 m 2 for temperate deciduous forest (Tanaka and Nakashizuka 1997;Henbo et al 2004;Kenderes et al 2008Kenderes et al , 2009). The majority of gaps belong to the smallest size categories of 20-50 m 2 (Kenderes et al 2009).…”

Gap dynamics in a near-natural spruce forest at Mt. Brocken, Germany

“…the long-term canopy study in a temperate old-growth beech forest in Japan based on aerial photographs over 43 yrs carried out by Henbo et al (2004), who found gap formation rates about four times higher than at Mt. Brocken (see Table 4).…”

Patch structure and ramet demography of the clonal tree, Asimina triloba, under gap and closed-canopy

“…The appearance and closure of canopy gaps in forests adds a temporal component to variations in the light environment beneath the canopy. The average rate of gap openings, for example, has been estimated as much as 0.4%-1.3% of total area per year in temperate hardwood forests (McCarthy 2001;Henbo et al 2004;Busing 2005). Even small gap openings caused by death of a large branch or a single canopy tree generally increase light availability for understory plants but they are followed by gap closure within a decade (Beaudet et al 2004).…”