Effects of herbivores and litter on Lithocarpus hancei seed germination and seedling survival in the understorey of a high diversity forest in SW China

摘要

Tanoak Lithocarpus hancei (Fagaceae) is one of the dominant species in the high diversity subtropical evergreen broad-leaved forests in SW China. However, seedlings of L. hancei and other oaks are quite rare in the understorey. To investigate the effects of seed (acorn) predation and seedling herbivory by mammals, and litter, on acorn germination and seedling survival of L. hancei in these forests, we set up a 2 x 2 factorial experiment (litter present or removed; +/- herbivore exclosures (fences); plus natural control; 5 replications) in the Ailaoshan National Nature Reserve, central Yunnan from 2010 to 2015. Acorns and transplanted seedlings of L. hancei were placed in the four treatments plots and the influence of these treatments on acorn germination and seedling survival was monitored. Fences protected L. hancei acorns and seedlings against herbivory by rodents and other mammals; litter had a positive effect on acorn survival but no effect on seedling establishment. Moreover, those seedlings that escaped herbivory were mostly killed by fungal attack. Our results indicate that while litter and pathogens have some influence, herbivores are probably the major cause of the low frequency of L. hancei seedlings in the understorey.