Effects of Local and Regional Processes on Herbaceous Plant Assemblages in the Betula utilis Forest Gaps of Taibai Mountain

Authors He Shuzhen; Wang Dexiang; Yang Gaihe; Li Gang; Qin Xiaowei; Yang Junjie; Quan You; Wang Chen

Journal Acta Botanica Boreali-Occidentalia Sinica , 2012,1:32

Abstract It has been widely confirmed that canopy gap disturbances can promote species richness of forest communities.However,whether plant assemblage within a canopy gap is constrained by local or regional processes remains a contentious issue in plant ecology.To investigate the contrasting roles of local processes and regional processes,we examined the relationships between the number of herbaceous plant species at two small-scales(in 0.25 m~2 and 1 m~2 quadrats) within the gap and the whole herbaceous plant species in the surrounding gap in the Betula utilis forest of Taibai Mountain.The results showed that:(1)species richness at 0.25 m~2 and 1 m~2 local scales significantly correlated with the number of available species in the surrounding gap(r=0.791 and r=0.861).And the two local-scales species richness showed a positive function of regional species richness,respectively.But the local and regional species richness significantly increased with increasing gap sizes,which may generate a spurious relationship between local and regional species richness.(2)The significant positive local-regional relationship was persisted controlling for the effect of gap size in multiple regression(R~2=0.642 for 0.25 m2 scale and R2=0.743 for 1 m2 scale).Moreover,analysis of variance depicted that gap size only explained 4.0% and 4.4% of the variation in local species richness at 0.25 m2 and 1 m2 quadrats,respectively;While,regional species richness accounted for 25.8% and 35.3% after gap size was controlled,respectively.These results suggested that local-scale species richness can be constrained by regional species richness in the surrounding canopy gaps.

Species covered 糙皮桦(原变种) Betula utilis