Given the high-level physiological functions and nutrient concentrations of bark that cover the entire trunks of huge trees,research into bark nutrient traits and the development of models that estimate the bark bioma...Given the high-level physiological functions and nutrient concentrations of bark that cover the entire trunks of huge trees,research into bark nutrient traits and the development of models that estimate the bark biomass of tropical trees is essential when it is sought to understand forest nutrient cycling and tree ecological traits.This study investigated the concentrations of six bark nutrients(nitrogen(N),phosphorus(P),potassium(K),calcium(Ca),magnesium(Mg),and sodium(Na))by individual tree size and the soil nutrient concentrations for two major pioneer species(Macaranga gigantea and M.hosei)of Malaysia.To estimate bark biomass,allometric equations using tree diameter,height,and crown diameter were developed by combining previous data from adjacent forests with the present data.We found no significant relationship between tree size and most bark nutrient concentrations,though all nutrient concentrations of the two pioneer trees were significantly higher than those of primary forest tree species.Surprisingly,no relationship was found between the soil and bark nutrient concentrations for either species.All the size parameters used in the allometric equations accurately estimated bark biomass.There were no differences in equations between the two species when diameter served as an explanatory variable,but differences were apparent when height and crown diameter were so used.A comparison of allometric equations that yielded the bark biomasses of different types of forest showed that the bark biomass of the tropical secondary forest trees was less than half of that of tropical dry forest trees of the same diameter.Thus,the use of inappropriate equations and nutrient concentrations increases the possibility of serious errors in estimating bark biomass and forest nutrient cycles.展开更多
This paper outlines the nature of microplastic contamination in rivers and the risks to freshwater fishes.We discuss how input sources influence the concentration and composition of microplastics and examine factors t...This paper outlines the nature of microplastic contamination in rivers and the risks to freshwater fishes.We discuss how input sources influence the concentration and composition of microplastics and examine factors that subsequently influence their spatiotemporal dynamics in a river system.We then discuss how the distributions and assemblages of microplastics can impact the risk of interactions with fishes,and the processes associated with the internalisation of microplastic into the body and across the organs and tissues.Finally,we examine the physical and toxicological effects of microplastic exposure in fish species,with special attention directed towards impacts at environmentally relevant concentrations.This review integrates expertise in fluvial geomorphological processes and how they influence the movement and storage of microplastics in river channel environments at a range of scales.We combine this knowledge with expertise in fish ecology and biology to set out a new and integrated analysis of microplastic dynamics in rivers and how these microplastics interact with fish.The integration of knowledge from these fields allows us also to comment upon the microplastic risk to fish and other biota in river environments.展开更多
基金supported in part by Grants-in-Aid for Scientific Research(Nos.24405032,17H04623,20K06153 and 21H05316)JST/JICA,SATREPS(JPMJSA1902)an Adaptive Forestry research program from the Japan International Research Centre for Agricultural Sciences.
文摘Given the high-level physiological functions and nutrient concentrations of bark that cover the entire trunks of huge trees,research into bark nutrient traits and the development of models that estimate the bark biomass of tropical trees is essential when it is sought to understand forest nutrient cycling and tree ecological traits.This study investigated the concentrations of six bark nutrients(nitrogen(N),phosphorus(P),potassium(K),calcium(Ca),magnesium(Mg),and sodium(Na))by individual tree size and the soil nutrient concentrations for two major pioneer species(Macaranga gigantea and M.hosei)of Malaysia.To estimate bark biomass,allometric equations using tree diameter,height,and crown diameter were developed by combining previous data from adjacent forests with the present data.We found no significant relationship between tree size and most bark nutrient concentrations,though all nutrient concentrations of the two pioneer trees were significantly higher than those of primary forest tree species.Surprisingly,no relationship was found between the soil and bark nutrient concentrations for either species.All the size parameters used in the allometric equations accurately estimated bark biomass.There were no differences in equations between the two species when diameter served as an explanatory variable,but differences were apparent when height and crown diameter were so used.A comparison of allometric equations that yielded the bark biomasses of different types of forest showed that the bark biomass of the tropical secondary forest trees was less than half of that of tropical dry forest trees of the same diameter.Thus,the use of inappropriate equations and nutrient concentrations increases the possibility of serious errors in estimating bark biomass and forest nutrient cycles.
基金funded by a PhD scholarship from the Ministry ofHigher Education Malaysia(Skim Latihan Akademik Bumiputera).
文摘This paper outlines the nature of microplastic contamination in rivers and the risks to freshwater fishes.We discuss how input sources influence the concentration and composition of microplastics and examine factors that subsequently influence their spatiotemporal dynamics in a river system.We then discuss how the distributions and assemblages of microplastics can impact the risk of interactions with fishes,and the processes associated with the internalisation of microplastic into the body and across the organs and tissues.Finally,we examine the physical and toxicological effects of microplastic exposure in fish species,with special attention directed towards impacts at environmentally relevant concentrations.This review integrates expertise in fluvial geomorphological processes and how they influence the movement and storage of microplastics in river channel environments at a range of scales.We combine this knowledge with expertise in fish ecology and biology to set out a new and integrated analysis of microplastic dynamics in rivers and how these microplastics interact with fish.The integration of knowledge from these fields allows us also to comment upon the microplastic risk to fish and other biota in river environments.
