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
The heavy metal contents of 54 organic fertilizer samples from Hunan Province were detected;meanwhile,through field plot experiments,the accumulations of heavy metals from chicken excrement-based organic fertilizer in...The heavy metal contents of 54 organic fertilizer samples from Hunan Province were detected;meanwhile,through field plot experiments,the accumulations of heavy metals from chicken excrement-based organic fertilizer in soil and vegetables under different fertilization methods were studied.The experiment results indicated that:(1)The average contents of Pb,Cd,Cr,As,Hg,Cu,Zn and Ni in the sampled fertilizers were 8.18,0.77,17.80,2.80,0.83,70.36,198.84 and 81.48 mg/kg,respectively;Cu and Zn exceeded the most than their standards,followed by As,Hg,Cd and Cr.(2)Among the organic fertilizers produced by different raw materials,industrial sludge contained the highest content of heavy metals,followed by the livestock excrements,oil-seed-meals and crop straw.(3)Only applying chemical fertilizer had a relatively small in fluence on the accumulation of heavy metal in soil while decreasing its pH value;the mixture of chemical fertilizer and chicken manure could increase the pH value in soil while accumulating little heavy metals.It is recommended that the mixture of chemical fertilizer and chicken manure should be a prior choice so as to improve soil property and ensure the safety of agricultural products.Moreover,when applying double amount of chicken manure,the contents of 8 heavy metals in soil were increased,among which Cd,Cu,Zn had obtained obvious accumulation effects,which were higher than applying a single portion of chicken manure fertilizer.(4)After two years of the field plot experiments,the accumulation of heavy metal in vegetables was not obvious under all designed fertilization modes,though increasing slightly.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Supported by Plan for Agricultural Product Quality and Safety Risk Assessment Project of China(GJFP201701202)~~
文摘The heavy metal contents of 54 organic fertilizer samples from Hunan Province were detected;meanwhile,through field plot experiments,the accumulations of heavy metals from chicken excrement-based organic fertilizer in soil and vegetables under different fertilization methods were studied.The experiment results indicated that:(1)The average contents of Pb,Cd,Cr,As,Hg,Cu,Zn and Ni in the sampled fertilizers were 8.18,0.77,17.80,2.80,0.83,70.36,198.84 and 81.48 mg/kg,respectively;Cu and Zn exceeded the most than their standards,followed by As,Hg,Cd and Cr.(2)Among the organic fertilizers produced by different raw materials,industrial sludge contained the highest content of heavy metals,followed by the livestock excrements,oil-seed-meals and crop straw.(3)Only applying chemical fertilizer had a relatively small in fluence on the accumulation of heavy metal in soil while decreasing its pH value;the mixture of chemical fertilizer and chicken manure could increase the pH value in soil while accumulating little heavy metals.It is recommended that the mixture of chemical fertilizer and chicken manure should be a prior choice so as to improve soil property and ensure the safety of agricultural products.Moreover,when applying double amount of chicken manure,the contents of 8 heavy metals in soil were increased,among which Cd,Cu,Zn had obtained obvious accumulation effects,which were higher than applying a single portion of chicken manure fertilizer.(4)After two years of the field plot experiments,the accumulation of heavy metal in vegetables was not obvious under all designed fertilization modes,though increasing slightly.
