Sprouting Characteristics And Its Effects On Biodiversity In An Evergreen Broad-leaved Forest In 5ha Plots In Gutianshan

The area of subtropical evergreen broad-leaved forest is becoming smaller and smaller because of anthropogenic disturbance and land use change,with the degradation of structure and function.Scientific conservation and restoration of subtropical evergreen broad-leaved forest have being become more and more important.Sprout regeneration is an effective mean for maintaining ecosystem stability and has an important significance to vegetation succession and healthy development of evergreen broad-leaved forest.However,most previous studies treated sprout regenerration as seed regeneration,resulting in shallow understanding of both the sprouting characteristics and importance of woody plants.The investigation of characteristics of sprout regeneration in subtropical evergreen broad-leaved forests could help us understand the status of sprout regeneration in communities,and will provide scientific evidence for conservation,restoration and construction of subtropical evergreen broad-leaved forest.In this study,based on a 5ha plot in Gutianshan national natural reserve,we analyzed the characteristics of sprout regeneration,tested the relationships between sprouting ability and biodiversity,and compared growth strategies of sprouting regeneration and seeding regeneration by leaf functional traits.The results showed that:1.We record 147 species(belongs to 46 families and 100 genus)in 5 ha plot.Among them,94 species(belongs to 33 families and 60 genus)could regenerate by sprouting,and the richness proportion of sprouting trees is 63.95%.The total number of individuals of the plots is 23450.The number of sprouting individuals is 9036 and the abundance proportion of sprouting trees is 38.53%.The number of potential sprouting individual,which could be sprouting species but does not sprout yet,is 13955,with the abundance proportion reaching up to 59.51%.As for trees,Castanopsis eyrei,Cyclobalanopsis glauca,etc have more sprouting individuals;as for shrubs,Chimonanthus salicifolius,Camellia fraterna,Rhododendron ovatum,etc have more sprouting individuals.Corylopsis glandulifera,Chimonanthus salicifolius,Cyclobalanopsis glauca,Lithocarpus glaber,etc have stronger sprouting ability.Sprouting species mainly occurre in the families of Fagaceae,Ericaceae,Hamamelidaceae and Theaceae.The sprouting ability of community in forest gaps(0.39)is significantly stronger than that in understory(0.30,p=0.009).2.In 5ha plot,there is no significant relationships between richness proportion of sprouting individuals and species richness,Shannon-Wiener index,Simpson index and Pielou evenness index.However,abundance proportion of sprouting individuals developes a significant negative relationships with Shannon-Wiener index,Simpson index and Pielou evenness index.With the increase of sprouting abilty of community,the diversity index of community have a declined tendency.Nevertheless,in forest gaps,sprouting ability of community do not develope a significant relationship with species richness,Simpson index and Shannon-Winner index,except that the abundance proportion of sprouting individuals have a negative effect on the Pielou evenness index.3.Based on saplings’leaf functional traits,we find:1)in understory,as for Camellia fraterna,Castanopsis eyrei,Castanopsis fargesii,Syzygium buxifolium,there exists no significant differences between seedling regeneration and sprouting regeneration in chlorophyll content,leaf area,specific leaf area and leaf dry-matter content except that seedling Ardisia crenata has high chlorophyll content.2)in forest gaps,seedling Camelia fraterna and sprouting Castanopsis eyrei both have big leaf area,seedling Syzygium buxifolium has high chlorophyll content and leaf dry-matter content,and sprouting Castanopsis fargesii has big leaf area and high chlorophyll content.3)as for sprouting regeneration,Camellia fraterna in understory has big leaf area,Eurya rubiginosa in understory and Castanopsis eyrei in forest gaps have high chlorophyll content and leaf dry-matter content,Castanopsis fargesii in forest gaps has high chlorophyll content,but 4 leaf functional traits of Chimonanthus salicifolius,Ardisia crenata,Syzygium buxifolium in understory is similar to that in forest gaps.All these results show that it is a common phenomenon that woody species could regenerate by sprouting and that sprout regeneration occupy an important position in subtropical evergreen broad-leaved community.Sprouting strategy could ensure its persistence and suppress the development of community diversity at the same time.However,after disturbance happens,species could rapidly recover previous niche by sprout regeneration,which may contribute to the increaseing of biodiversity.Based on saplings’ leaf functional traits,we find that comparied with saplings originating as seedlings,saplings originating as sprouts do not dominate,indicating that sprouting saplings do not need form powerful leaf traits to compete with seedlings by supplies of carbohydrates from strong roots and other sprouting saplings.So we conclude that sprouting regeneration’s important effect and role in forest may be not in the leaf functional traits,but may be in other aspects.Different sprouting species have different leaf growth strategies,for example,sprouts of shrubs prefer to shade environment,while sprouts of trees adapt to the habitat of forest gaps,suggesting that species in different phylogenetic position may have evolve different sprouting strategies.Evolutionary history of species may have an important effect on the sprouting strategy.The existence of sprouting in community has an important role in regulating species coexistence and the maintenance of biodiversity.