A chronosequence of understorey parasitic wasp assemblages in secondary broad‐leaved forests in a Japanese ‘satoyama’ landscape

Abstract

1. To infer the effects of forest aging on the abundance, genus richness and diversity, and genus composition of understorey parasitoids, we investigated the assemblages of braconids collected in Malaise traps in a chronosequence of secondary broad-leaved forests (4-128 years old) in the satoyama landscape in the cooltemperate region of central Honshu, Japan.2. Multivariate linear regression analysis indicated that the abundance of braconid parasitoids was affected by forest age (time since clear-cutting) in the secondary broad-leaved forests, although the effects on genus richness and diversity were not statistically supported.3. The abundance of herbivore parasitoids decreased significantly with forest age. This is probably caused by the decline of insect herbivores associated with the decrease in forest floor vegetation along the chronosequence.4. The opposite trend was observed for detritivore parasitoids, which significantly increased in abundance with forest age, probably along with forest floor litter mass, though no significant change in the abundance of wood-borer parasitoids was observed with forest age.5. Genus composition of braconid parasitoids was affected by forest age, as determined by canonical correspondence analysis. Genera of detritivore parasitoids were mostly confined to older plots, those of herbivore parasitoids were rather abundant in younger plots, and those of wood-borer parasitoids were more broadly distributed.6. Therefore, we conclude that the presence of mixed forest stands of various age classes at the landscape level would contribute to the conservation of diverse assemblages of host insects and their parasitoids.

Differential Responses of Herbivores and Herbivory to Management in Temperate European Beech

“…Throop and Lerdau [56] confirmed the assumption of a positive effect of high nitrogen content on the individual performance of sap-sucking insects and their population levels and Gossner et al [57] proposed similar mechanisms for the higher percentage of sap-sucking Heteroptera in young oak stands on former agricultural fields compared to forest sites due to differences in plant stress. Maleque et al [58] found a general decrease of understorey insect herbivores with forest age which was attributed to the general decrease in forest floor vegetation with stand age. In our study, plant diversity positively affected most herbivores, among these miners, and thus plant diversity might partly explain observed patterns ( Table 3 , see also below).…”

Tree phylogenetic diversity promotes host–parasitoid interactions

“…However, for parasitoids and host -parasitoid systems evidence for cross-taxon congruence with tree species richness or other coarse measures of habitat heterogeneity is sparse and inconclusive. Depending on the study system, parasitoid abundance and species richness increased [13][14][15], were unrelated [43] or declined [44] with habitat heterogeneity, but no study considered descriptors of PD such as tree MPD. As introduced above, a plant community's PD is a suitable surrogate for overall niche availability and habitat heterogeneity [21,23], and more diverse evolutionary lineages will result in more diverse microhabitats.…”

Crises of Biodiversity and Ecosystem Services in Satoyama Landscape of Japan: A Review on the Role of Management

“…Considering the succession series of forest husbandry, there are nine periodic habitat series in forest ecosystems ( Figure 2). First, frequent cutting and thinning of woodlands led to the domination of dwarf pines and coppices, and decreased the occurrence of invasive species and increased forest floor species diversity [49,50]. Second, collecting fallen leaves for fertilizer as well as the regular cutting of deciduous forests supports many species of spring and summer wildflowers, which can survive only when the foliage is thin, and sunlight is able to reach the forest floor.…”