Araucaria angustifolia is the dominant coniferous species in Brazil,a long-lived pioneer species and a supplier of valuable timber and non-timber products,which gives it key-species status.This study examines how A.an...Araucaria angustifolia is the dominant coniferous species in Brazil,a long-lived pioneer species and a supplier of valuable timber and non-timber products,which gives it key-species status.This study examines how A.angustifolia population structure affects the stand structure,and whether these relationships differ between protected and unprotected areas.The study was carried out on two protection status forests(national forest and urban forest)in a region of Atlantic mixed forest in ParanáState,southern Brazil.Skewness coefficient and the Weibull shape parameter described the population structure and its effects on species diversity and biomass stock.Population diameter distribution differed significantly between forests,with unbalanced structure in both,although regeneration was more abundant in the protected area.Skewness positively affected aboveground biomass whereas shape negatively affected it and species diversity.These relationships differed between protected and unprotected stands.The effect of A.angustifolia populations on stand structure was conditioned on protection status.Old-growth populations may have lower diversity and biomass stock even supporting large trees.Consequently,old-growth forests,can lead to wood loss through mortality,senescence,and declining populations,representing the waste of a valuable timber resource.These findings provide useful knowledge for forest management,species conservation,and the carbon market.展开更多
The tropical Pacific Ocean supports many productive commercial fisheries.However,few studies of ecosystem structure in the tropical Pacific Ocean have been carried out.In this study,we analyzed the food web structure ...The tropical Pacific Ocean supports many productive commercial fisheries.However,few studies of ecosystem structure in the tropical Pacific Ocean have been carried out.In this study,we analyzed the food web structure in the central and eastern tropical Pacific Ocean based on trophic relationships of 35 pelagic species collected by Chinese tuna longline observers from June to November in 2017.Topology indices(node degree,D;centrality indices,BC and CC;topological importance indices,TI^1,TI^3;keystone indices,K,K_t and K_b)and Key-Player algorithms(KPP-1,KPP-2)were used to select key species and construct a simplified food web combined with body size data.The Kendall rank correlation and hierarchical clustering analysis indicated that different topology indices resulted in consistent rankings of key species.Most key species were the same as those selected in other studies in the Pacific Ocean,such as Shortbill spearfish(Tetrapturus angustirostris),Swordfish(Xiphias gladius),Albacore tuna(Thunnus alalunga),cephalopods and scomber.The food web would be separated into many unconnected parts(F=0.632,FD=0.795,R^D=0.957)after the removal of the five key species,indicating the key roles of these species in the food web structure and stability.Body size was considered an influential indicator in constructing the simplified food web.This study can improve our understanding of the food web structure in the tropical Pacific Ocean and provide scientific basis for further ecosystem dynamics studies.展开更多
基金supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico–CNPq,by granting the scholarship to first author (Process:150288/2020-4)。
文摘Araucaria angustifolia is the dominant coniferous species in Brazil,a long-lived pioneer species and a supplier of valuable timber and non-timber products,which gives it key-species status.This study examines how A.angustifolia population structure affects the stand structure,and whether these relationships differ between protected and unprotected areas.The study was carried out on two protection status forests(national forest and urban forest)in a region of Atlantic mixed forest in ParanáState,southern Brazil.Skewness coefficient and the Weibull shape parameter described the population structure and its effects on species diversity and biomass stock.Population diameter distribution differed significantly between forests,with unbalanced structure in both,although regeneration was more abundant in the protected area.Skewness positively affected aboveground biomass whereas shape negatively affected it and species diversity.These relationships differed between protected and unprotected stands.The effect of A.angustifolia populations on stand structure was conditioned on protection status.Old-growth populations may have lower diversity and biomass stock even supporting large trees.Consequently,old-growth forests,can lead to wood loss through mortality,senescence,and declining populations,representing the waste of a valuable timber resource.These findings provide useful knowledge for forest management,species conservation,and the carbon market.
基金The National Natural Science Foundation of China under contract No.41676120。
文摘The tropical Pacific Ocean supports many productive commercial fisheries.However,few studies of ecosystem structure in the tropical Pacific Ocean have been carried out.In this study,we analyzed the food web structure in the central and eastern tropical Pacific Ocean based on trophic relationships of 35 pelagic species collected by Chinese tuna longline observers from June to November in 2017.Topology indices(node degree,D;centrality indices,BC and CC;topological importance indices,TI^1,TI^3;keystone indices,K,K_t and K_b)and Key-Player algorithms(KPP-1,KPP-2)were used to select key species and construct a simplified food web combined with body size data.The Kendall rank correlation and hierarchical clustering analysis indicated that different topology indices resulted in consistent rankings of key species.Most key species were the same as those selected in other studies in the Pacific Ocean,such as Shortbill spearfish(Tetrapturus angustirostris),Swordfish(Xiphias gladius),Albacore tuna(Thunnus alalunga),cephalopods and scomber.The food web would be separated into many unconnected parts(F=0.632,FD=0.795,R^D=0.957)after the removal of the five key species,indicating the key roles of these species in the food web structure and stability.Body size was considered an influential indicator in constructing the simplified food web.This study can improve our understanding of the food web structure in the tropical Pacific Ocean and provide scientific basis for further ecosystem dynamics studies.
