Field estimation of interception in a broadleaf forest under multi-layered structure conditions

Abstract

Abstract:We performed a field experiment on throughfall, stemflow, and bamboo culm flow to estimate interception in a deciduous broadleaf forest with different stand structures by separately removing the overstory and understory vegetation. The study area is occupied by oak (Quercus serrata) and chestnut (Castanea crenata) with an understory of chino bamboo (Pleioblastus chino). We established three plots for vegetation control, including an overstory plot (removal of understory), a bamboo plot (removal of overstory), and a control plot (both overstory and understory remained). Throughfall amounts relative to precipitation were 61% in the control plot, 54% in the overstory plot, and 31% in the bamboo plot. Average stemflow in control and overstory plots was 3% of precipitation. The significant difference in throughfall for the bamboo plot may have been caused by the high density of understory vegetation. A large portion of intercepted water is transferred to the ground as bamboo culm flow in the understory beneath the canopy in the control plot and in the bamboo plot. Our experiment highlighted the significance of understory vegetation in altering hydrological processes from canopy to understory vegetation.

How Do Ground Litter and Canopy Regulate Surface Runoff?—A Paired-Plot Investigation after 80 Years of Broadleaf Forest Regeneration

“…The increase in surface runoff (4× from LRBC to AC) demonstrated the role of forest canopy in intercepting and evaporating rainwater in secondary broadleaf forests (Figure 9) [14,37,38]. Compared to other hydrological losses, canopy interception (12-24% throughout Japan) may have a distinctively large influence as it directly controls effective rainfall [14,21,39]. Studies from other regions also recorded similar values: 21.3% of rainfall in a tropical broadleaf forest in Kalimantan [40]; 10% and 20% in a primary and regenerated tropical rainforest, respectively, in Sabah, Malaysia [41]; and 22.4% in a conifer forest in California [42].…”

“…Surface runoff was the highest in the AC phase. The increase in surface runoff (4× from LRBC to AC) demonstrated the role of forest canopy in intercepting and evaporating rainwater in secondary broadleaf forests (Figure 9) [14,37,38]. Compared to other hydrological losses, canopy interception (12-24% throughout Japan) may have a distinctively large influence as it directly controls effective rainfall [14,21,39].…”

“…The focus on cypress plantation was a result of its rapid expansion between 1970 and 2000 that was driven by the government's economic policy. Up to date, temperate broadleaf forests and mixed-forests especially those which had undergone restoration have received relatively little attention, although there are some exemplary studies [13,14]. More specifically, the hydrological role of ground litter and the canopy are not yet well-understood.…”

“…Most studies that were conducted in Japan are related to the effects of thinning of conifer plantations, whereby thinning reduces canopy interception and may increase the likelihood of floods [21]. At the time of writing, the authors found only one study in Tochigi prefecture, eastern Japan, that reported canopy interception in a regenerated multi-layered broadleaf forest to be 21% [14]. The impacts on surface runoff from clearcutting broadleaf forests and mixed-forest remain unexplored.…”