Total And Effective Contents Of Trace Elements In Soil Of Native Tree Species Plantations And Natural Secondary Forest In South Tropical Region

In this paper,four tapical native tree species plantation,(Castanopsis hystrix,Mytilaria laosensis,Michelia macclurel,Pinus massoniana)and natural secondary forests,located in the Fubo Experimental Center of Chinese Tropical Forestry,Pingxiang,Guangxi,are studied in the Fubo Experimental Center of Chinese Tropical Forestry Research Institute of,forestry science which in the city of Pingxiang,Guangxi as the research object.Soil samples were collected by stratification(0-20,20-40 and 40-60cm).The differences of total and effective trace elements in soils between different stands in the same soil layer and different soil layers in the same forest layer were analyzed,and the effects of soil physical and chemical properties on total and effective trace elements in soils were discussed.The main conclusions are as follows:(1)The total soil Zn of natural secondary forest was significantly higher than that of four native tree species plantations in the same soil layer(P<0.05),but there was no significant difference in total soil Cu,Fe and Mn among four native tree species plantations in the same soil layer.(2)The available amounts of Cu,Zn and Mn in different soil layers of natural secondary forest were higher than those of four native tree species plantations,especially in the surface layer of natural secondary forest(0-20cm),the available amounts of Cu,Zn and Mn were significantly higher than those of four native tree species plantations(P<0.05),while the effective amounts of Fe were higher in all soil layers of Pinus massoniana plantations.(3)Among the five research stands,only the soil total Cu and total Zn of Michelia macclurel plantation in Mytilaria laosensis plantation were significantly higher in surface layer(0-20 cm)than in bottom layer(40-60 cm)(P<0.05).The soil available Fe of five studied forests had surface aggregation effect,and the soil surface available Fe was significantly higher than that of the bottom(P<0.05);the soil surface available Zn of Michelia macclurel plantation and natural secondary forest was significantly higher than that of the bottom,while the soil surface available Cu of Pinus massoniana Plantation and natural secondary forest was significantly higher than that of the bottom(P<0.05).(4)The effects of soil physical and chemical properties parameters on the total and effective contents of trace elements in the soil of the studied forests are different.Among them,soil pH value,water content,available phosphorus and available potassium were significantly correlated with soil total Mn(P<0.01),and soil available phosphorus was significantly correlated with available Cu.Ammonia nitrogen was significantly correlated with available Fe(P<0.05),total potassium and available potassium were significantly correlated with available Cu.Soil organic carbon,total nitrogen,nitrate nitrogen and available phosphorus were significantly correlated with available Fe.Soil pH,water content,total potassium and available potassium were significantly correlated with available zinc(P<0.01).