Climate influences the effect of fungal decay type on regeneration of Picea jezoensis var. hondoensis seedlings on decaying logs

Abstract

Hondo spruce (Picea jezoensis var. hondoensis (Mayr) Rehder)) is separately distributed among several mountainous regions in central Japan as remnant populations of the last glacial period. To identify factors that affect Hondo spruce seedling regeneration on decaying logs, we investigated the relationships between climatic conditions, log properties, including decay type by fungi, and Hondo spruce seedling density on logs using data from seven subalpine Hondo spruce forests in central Japan. The results showed that the presence of soft rot was associated with higher seedling density, and the effect of brown rot in sapwood and white rot in heartwood on the predicted number of spruce seedlings on logs switched from positive to negative with increasing temperature and precipitation. Because soft rot occurs under humid conditions, the use of forest management techniques that increase the number of logs with soft rot in sapwood (e.g., by keeping the forest floor moist) are recommended for the sustainable regeneration of Hondo spruce. However, the relationships between wood decay type and seedling regeneration can also be affected by climate condition and thus are more complex than previously thought.

Ecological impacts of fungal wood decay types: A review of current knowledge and future research directions

“…Consequently, the occurrence of brown-rotted P. jezoensis var. hondoensis logs was also negatively associated with precipitation in the same geographical area (Fukasawa et al, 2020).…”

“…This is particularly important for predicting ecological processes under climate change. For example, the clear climatic gradient in wood decay type frequency (Fukasawa, 2015a;Fukasawa et al, 2020; Figure 3) and the conspicuous effect of forest dieback on fungal community and wood decay type Figure 4) indicate that progressing climate change might alter the biogeography of wood decay types and related ecological processes.…”

Applying molecular and genetic methods to trees and their fungal communities

“…and detritivorous soil meso- and macrofauna with multiple pathways of turnover and accumulations of intermediate microbial and faunal transformation products, which is further influenced in interactions with the vegetation, with soil properties and (bio)chemistry, and also by climate parameters (Prescott and Vesterdal 2021 ; Veldkamp et al 2020 ). What is more, coarse wooden material degradation will prepare fermented porous-structured moisture-retaining nutritious grounds for better germination and rooting of seedlings and anchorage of developing trees (Fukasawa et al 2017 , 2020 ; Stroheker et al 2018 ) and provides also habitat for saproxylic communities (Fukasawa 2021 ). Seed beds of decaying logs or stumps may harbor less fungal seed pathogens and they can provide favoring associations of N 2 -fixing bacteria with specific selections of mycorrhiza-promoting fungi (Huusko et al 2015 ; Izumi et al 2006 ; Tedersoo et al 2008 ; Willis and Walters 2018 ).…”