Abstract:

Aims The Janzen-Connell hypothesis is that seed survival improves with increased distance from the parental plant. Our objectives were to determine whether the Janzen-Connell hypothesis (1) is supported by Castanopsis chinensis seed survival, (2) can forecast the population's distribution pattern, and (3) explains the reason for limited recruitment.

Methods We selected three mature C. chinensis trees in coniferous and broad-leaved mixed forest of Dinghushan, China and recorded seed mortality with Open treatments (OP), Small Mammal Exclusion experiments (EM) and pathogen infection treatments at 3, 10, and 15 m from the trees.

Important findings In the OP treatment, the number of missing seeds was largest at 10 m; however, seed predation was not significantly affected by distance from tree and seed size. In the EM treatment, few seeds were missing in the first week, and seed predation was not significantly affected by distance and seed size during the study period. In the first two months, seeds with Caoton treatment remained intact, and from the third to the sixth month, the number of seeds infected by pathogens was significantly affected by distance and disinfecting action. After the sixth month, the number of seeds infected by pathogens was relatively constant. These results illustrate that pathogens are related to mortality of seeds of C. chinensis and that this mortality is distance dependent, while the mortality caused by vertebrate animals is not distance dependent.

Key words: Castanopsis chinensis, seed dispersal, distance-dependent, seed predation, pathogen infection, seed size