Structure, species composition, and soil properties of a subtropical evergreen broad-leaved forest in Okinawa, Japan, were examined by establishment of plots at thirty sites. The forest was characterized by a relative...Structure, species composition, and soil properties of a subtropical evergreen broad-leaved forest in Okinawa, Japan, were examined by establishment of plots at thirty sites. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 5400 stems-ha^-1 （ -〉 3.0 cm DBH）; 64% of those stems were smaller than 10 cm DBH. The total basal area was 54.4 m^2-ha^-1, of which Castanopsis sieboldii contributed 48%. The forest showed high species diversity of trees. 80 tree species （≥ 3.0 cm DBH） from 31 families was identified in the thirty sampling plots. C. sieboldii and Schima wallichii were the dominant and subdominant species in terms of importance value. The mean tree species diversity indices for the plots were, 3.36 for Diversity index （H＇）, 0.71 for Equitability index （J＇） and 4.72 for Species richness index （S＇）, all of which strongly declined with the increase of importance value of the dominant, C. sieboldii. Measures of soil nutrients indicated low fertility, extreme heterogeneity and possible A1 toxicity. Regression analysis showed that stem density and the dominant tree height were significantly correlated with soil pH. There was a significant positive relationship between species diversity index and soil exchangeable K^＋, Ca^2＋, and Ca^2＋/Al^3- ratio （all p values 〈0.001） and a negative relationship with N, C and P. The results suggest that soil property is a major factor influencing forest composition and structure within the subtropical forest in Okinawa.展开更多
Aims Positive biodiversity-ecosystem functioning relationships have been widely reported,predominately from grassland ecosystems.However,this does not necessarily have to apply accordingly in more complex situations s...Aims Positive biodiversity-ecosystem functioning relationships have been widely reported,predominately from grassland ecosystems.However,this does not necessarily have to apply accordingly in more complex situations such as in forests across different vertical strata.For instance,overstorey tree species richness has been shown to be associated with a lower understorey productivity.Whether or not tree species richness effects add to understorey productivity by increasing(i.e.due to habitat heterogeneity)or reducing resource availability(i.e.through increasing competition)and whether understorey productivity is indeed being governed more strongly by tree species identity are likely to change over time.Moreover,studies also suggested that richness-productivity relationships change with the environmental context.Using an experimental forest plantation with manipulated tree species richness,this study examined these temporal and environmental dynamics across strata.Methods In the context of the Biodiversity-Ecosystem Functioning project in subtropical China(BEF-China),we made use of understorey biomass samples repeatedly collected over a time period of 3 years along a tree species richness gradient.The effects of tree species richness,tree species identities and time were studied across different environmental treatments for their impact on understorey biomass.Important Findings While we found significant and consistent tree layer identity effects on understorey biomass,no such effect was encountered for tree species richness.Our results also indicate that among structural layers in forests,there might not be a single,generalizable overstorey species richness-understorey productivity relationship,and that the extent as to which overstorey-related environmental factors such as light transmittance contribute to understorey productivity change with time.Overall,we demonstrate that temporal dynamics should be considered when studying relationship among structural layers in forests.展开更多
基金supported by National Natural Science Foundation of China (No.30471386)Japanese Society for Promotion of Sciences (15P03118)
文摘Structure, species composition, and soil properties of a subtropical evergreen broad-leaved forest in Okinawa, Japan, were examined by establishment of plots at thirty sites. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 5400 stems-ha^-1 （ -〉 3.0 cm DBH）; 64% of those stems were smaller than 10 cm DBH. The total basal area was 54.4 m^2-ha^-1, of which Castanopsis sieboldii contributed 48%. The forest showed high species diversity of trees. 80 tree species （≥ 3.0 cm DBH） from 31 families was identified in the thirty sampling plots. C. sieboldii and Schima wallichii were the dominant and subdominant species in terms of importance value. The mean tree species diversity indices for the plots were, 3.36 for Diversity index （H＇）, 0.71 for Equitability index （J＇） and 4.72 for Species richness index （S＇）, all of which strongly declined with the increase of importance value of the dominant, C. sieboldii. Measures of soil nutrients indicated low fertility, extreme heterogeneity and possible A1 toxicity. Regression analysis showed that stem density and the dominant tree height were significantly correlated with soil pH. There was a significant positive relationship between species diversity index and soil exchangeable K^＋, Ca^2＋, and Ca^2＋/Al^3- ratio （all p values 〈0.001） and a negative relationship with N, C and P. The results suggest that soil property is a major factor influencing forest composition and structure within the subtropical forest in Okinawa.
基金This work was supported by the German Research Foundation(DFG FOR 891/3)with a grant to A.E.(ER 573/1-3).
文摘Aims Positive biodiversity-ecosystem functioning relationships have been widely reported,predominately from grassland ecosystems.However,this does not necessarily have to apply accordingly in more complex situations such as in forests across different vertical strata.For instance,overstorey tree species richness has been shown to be associated with a lower understorey productivity.Whether or not tree species richness effects add to understorey productivity by increasing(i.e.due to habitat heterogeneity)or reducing resource availability(i.e.through increasing competition)and whether understorey productivity is indeed being governed more strongly by tree species identity are likely to change over time.Moreover,studies also suggested that richness-productivity relationships change with the environmental context.Using an experimental forest plantation with manipulated tree species richness,this study examined these temporal and environmental dynamics across strata.Methods In the context of the Biodiversity-Ecosystem Functioning project in subtropical China(BEF-China),we made use of understorey biomass samples repeatedly collected over a time period of 3 years along a tree species richness gradient.The effects of tree species richness,tree species identities and time were studied across different environmental treatments for their impact on understorey biomass.Important Findings While we found significant and consistent tree layer identity effects on understorey biomass,no such effect was encountered for tree species richness.Our results also indicate that among structural layers in forests,there might not be a single,generalizable overstorey species richness-understorey productivity relationship,and that the extent as to which overstorey-related environmental factors such as light transmittance contribute to understorey productivity change with time.Overall,we demonstrate that temporal dynamics should be considered when studying relationship among structural layers in forests.
