The patch mosaic of an old‐growth warm‐temperate forest: patch‐level descriptions of 40‐year gap‐forming processes and community structures

Abstract

Old-growth forests consist of various types of small patches that reflect their own gap-forming process, which includes changes in environmental conditions occurring over several decades. We reconstructed the gap-forming processes that had occurred during a 40-year period for eight representative patches of an oldgrowth evergreen broad-leaved forest in Japan, and examined the current community structure. The selected patches were based on (1) changes in canopy heights estimated from aerial photographs taken in four different years, (2) long-term ecological research (LTER) monitoring records, and (3) a recent field survey, so that they sufficiently covered characteristic gap-forming processes such as a new gap, an old gap and consistently closed canopy. Height and diameter at breast height (DBH) were measured on all living trees taller than 1.3 m. In their height distributions, currently almost closed patches that were open in 1966 show a rotated sigmoid, whereas their DBH distributions are an inverse J-shape. In contrast, patches that have been consistently under a closed canopy exhibit gentle inverse J-shapes for both distributions. For species composition, there are no clear contrasts associated with the past gap-forming processes except for the existence of fast-growing deciduous species in large currently open patches. Our results suggested that the variation in several decades of gap-forming processes played a central role in the high patch diversity and the complex patch mosaic of the forest. Diverse gap-forming processes created microenvironmental heterogeneity both vertically and horizontally, and contributed to the maintenance of the species-rich, warm-temperate old-growth forest.

Stand Dynamics and Biomass Increment in a Lucidophyllous Forest over a 28-Year Period in Central Japan

“…Forests 2017, 8,397 3 of 14 11th century. Thus, a typical pioneer tree, Pinus densiflora, which was utilized as fertilizer or fuel by residents, predominated on and around this area historically.…”

“…Ohsawa [3] suggested that the tropical lower montane forests that are mainly dominated by evergreen Fagaceae (especially Castanopsis) can be correlated to the horizontal subtropical/warm-temperate zone of East Asia as lucidophyllous forests, and the latitudinal northern limit reaches sea level at 35 • N of central Japan. There have been several long-term studies that investigated the structure and the dynamics of the unique forests using large permanent quadrats in southwestern Japan; e.g., Aya Research Site from 1989 [4][5][6] or Tatera Forest reserve from 1990 [7][8][9]. These studies have revealed that diverse gap-forming processes created environmental heterogeneity in the forest floor and contributed to the maintenance of the species-rich evergreen broad-leaved forests.…”

Estimation of kelp forest, Laminaria spp., distributions in coastal waters of the Shiretoko Peninsula, Hokkaido, Japan, using echosounder and geostatistical analysis

“…Conversely, the range in the western area (1697 m) was three times longer than that of the eastern area (530 m). These differences in semivariogram parameters indicate that the occurrence of kelp forest in eastern areas are more horizontally variable with patches or gaps [26,27] than that in western areas.…”

A comparison of different survey methods for assessing gap parameters in old-growth forests

“…Canopy openings created by tree or branch falls greatly influence forest structure and floristic composition (Runkle, 1981), and gap formation plays an important role in maintaining tree species diversity (Denslow, 1987;Manabe et al, 2009). Therefore, examining the actual state of canopy gaps in forests is critically important for evaluating forest community structure and dynamics and for comparing gap disturbance regimes among different forests.…”