No. 909

Title:

Effects of litter dynamics on the survival of Castanopsis sieboldii seedlings in a subtropical forest, southern Japan

Author(s):

Kubota Yasuhiro (Kagoshima University);Shimatani Kenichiro (The Institute of Statistical Mathematics)

Key words:

Castanopsis seiboldii; Janzen-Connell model; micro-topography; litter movement; safe site

Abstract:

This study first quantitatively estimated the litter dynamics on the forest floor, and then investigated its influence on the seedling dynamics of Castanopsis sieboldii, as well as interactions with adults in a subtropical forest, southern Japan. Accumulated litter is composed of three major components, falling litter, transport, and deposition on the forest floor. The turnover time was largely governed by micro-topography. Combining litter dynamics (abiotic factors) with the distance effects between seedlings and adults (biotic factor), we constructed survival models of seedlings at the individual level. Model parameters were optimized using the maximum likelihood method, and their validity was comparatively examined with Akaike’s Information Criterion (AIC). In addition to the spatiotemporal variation on the mortality of seedlings, the lateral movement of accumulated litter had a great influence on the survival of seedlings, which mostly occurred in periods of typhoons with heavy rain. In contrast, Janzen’s spacing mechanisms played a lesser role in this subtropical forest, which has extensive environmental heterogeneity on the forest floor. Our results suggest that the stability of accumulated litter on the forest floor was a predominant factor in the spatial dynamics of the early life stage of C. sieboldii.