Study on Neighbor Effects of Three Dominant Species in the Evergreen-deciduous Mixed Forest in Jiugongshan Natural Reserve

Abstract

Neighbor effects of three dominant species Cyclobalanopsis glauca,Castanopsis eyrei and Quercus serrata var.brevipetiolata in an old-growth evergreen-deciduous mixed forest in Jiugongshan Natural Reserve were examined by nearest neighbor distance statistics,and the importance of competition/facilitation and implications for local species co-existence were explored.There were no lower limits of nearest neighbor distance for any species.The size(e.x.DBH) of Cyclobalanopsis glauca was positively correlated with its intraspecific nearest neighbor distance(p=0.029),but the size of Quercus serrata var.brevipetiolata was negatively correlated with its interspecific nearest neighbor distance(p= 0.040).No significant correlations were detected between size of Castanopsis eyrei and either of its interspeci-fic/intraspecific nearest neighbor distance(p≥0.360).Intraspecific nearest neighbor distances differed insignificant from interspecific ones for all species(p≥ 0.122).Our results imply that local competition has not been fully sharpened in the old-growth evergreen-deciduous mixed forest in Jiugongshan Natural Reserve.Neighbor effects were species-specific,with intraspecific competition in Cyclobalanopsis glauca being evident,competitive/facilitative effects of Castanopsis eyrei unobvious if not negligible,and dependence of Quercus serrata var.brevipetiolata on interspecific facilitation over competition.The insignificant differences between interspecific and intraspecific nearest neighbor distance for all species suggest that stochastic processes rather than negative density-dependent processes drove local species co-existence.