Sixty‐year post‐windthrow study of stand dynamics in two natural forests differing in pre‐disturbance composition

Abstract

Citation: Kosugi, R., M. Shibuya, and S. Ishibashi. 2016. Sixty-year post-windthrow study of stand dynamics in two natural forests differing in pre-disturbance composition. Ecosphere 7(11):e01571. 10.1002/ecs2.1571Abstract. We examined the dynamics of stand structure and composition over 60 years in two natural secondary forest plots in central Hokkaido, Japan, that had been severely disturbed by a stand-replacing windthrow in 1954. We determined temporal trends in tree density, species richness, species diversity, successional composition, and stand developmental stage. One of the plots contained a coniferous stand prior to the disturbance; the second plot contained a mixed stand. Tree density and species richness increased after the windthrow, and peaked in both stands in 1991, 37 years after the windthrow. Based on the dynamics of tree density and species richness, the stand development phase of both plots remained within the stand initiation stage until 1991, and then progressed to the stem exclusion stage by 2014, 60 years after the windthrow. Based on patterns of increasing tree density by species in both plots, vegetative regeneration was presumed to have contributed abundantly to the recovery of the stand after the windthrow. Species diversity increased after the windthrow as species richness increased in both stands; diversities peaked 23 or 32 years after the windthrow and declined slightly thereafter. Although the successional composition of the pre-disturbance coniferous stand regressed to an early stage under the influence of the windthrow, the relative importance of late-successional species approached the pre-disturbance value as the plot recovered. In contrast, the successional composition of the mixed conifer/hardwood plot was unaffected by the windthrow, but gradually changed to an early stage over several decades following the windthrow. The difference in successional composition between plots was likely a result of differences in pre-disturbance stand conditions between stands. Our 60-year permanent plot study determined stand and population dynamics, the duration of the stand initiation stage, and the interrelationships between diversity and species richness. Long-term permanent plot studies contribute crucial data for the interpretation of forest dynamics following disturbance.

The influence of landscape context on short‐ and long‐term forest change following a severe ice storm

“…By 2017, 19 years after the storm, average stem density of shrubs and saplings had declined nearly to original levels. This peak and subsequent decline in the density of shrubs and saplings is a common finding in studies of forests after natural disturbances, although the timing of the peak varies between regions (Heartsill Scalley, Scatena, Lugo, Moya, & Estrada Ruiz, ; Kosugi et al, ; Tremblay et al, ; White, MacKenzie, & Busing, ; Zhao et al, ).…”

“…First, it may take longer than the 19 years in our study for species richness to return to pre‐storm conditions (eg. Kosugi et al, ; Liu, Liu, Skidmore, & Garcia, ; Metzger et al, ). For example in a 60‐year study of two forests in Japan following a typhoon, Kosugi et al () found that species richness peaked 37 years after the storm, before declining gradually.…”

“…Kosugi et al, ; Liu, Liu, Skidmore, & Garcia, ; Metzger et al, ). For example in a 60‐year study of two forests in Japan following a typhoon, Kosugi et al () found that species richness peaked 37 years after the storm, before declining gradually. Alternatively, the ice storm may have allowed colonization by new species that are able to establish permanently.…”

“…Many studies have found that natural disturbances increase forest diversity (e.g. Fischer et al, ; Heartsill Scalley et al, ; Kosugi et al, ). By 2017, canopy damage was no longer a significant predictor of the change in species richness since the storm, once other predictors were accounted for.…”

“…Finally, natural disturbances can affect forest succession. In some cases, large natural disturbances set succession back to an earlier stage by killing larger, late‐seral species and therefore favouring younger, pioneer species (Kosugi, Shibuya, & Ishibashi, ). In other cases, disturbance accelerates succession, by removing lingering early‐seral species that had been slowing the rise to dominance of late‐seral species (Abrams & Scott, ; Allen, Thapa, Arévalo, & Palmer, ; Rhoads et al, ; Zhao, Allen, & Sharitz, ).…”