The Characteristics Of Vegetation And Soil Quality During The Aerially Seeded Pinus Massoniana Plantations Restoration

We took the aerially seeded Pinus massoniana plantations of Xingguo County,Jiangxi Province as the research object.The effects of vegetation restoration time on vegetation growth and soil quality were studied using space instead of time method.The age classes in years for aerially seeded Pinus massoniana plantations are as follows: II(11-20 a),III(21-30 a),IV(31-40 a)and V(41-50 a).The data was obtained through the sample-plot survey and determination of sample,which was to analyze the characteristics of vegetation and soil quality at different age classes.The change rules of vegetation characteristics and soil quality with vegetation restoration and the relationship between soil quality and vegetation factors were discussed.The results can provide reference for the development of succession measures and scientific management of aerially seeded Pinus massoniana plantations.The main results of the research were as follows:(1)There was an increase in the average diameter at breast height(DBH)and the volume with the increase of age class.Among them,the average DBH at III,IV and V age classes was significantly higher than that of II age class,respectively(P<0.05).The volume at V age class was significantly higher than that of II,III and IV age classes(P<0.05),and the volume at IV age class was significantly higher than that of II age class(P<0.05).There were no significant differences at average DBH and volume among other age classes(P<0.05).(2)There were 47 species in four age classes at the aerially seeded Pinus massoniana plantations,included 25 shurb plants and 22 herbaceous plants,which belonged to 42 genera and 23 families.The dominant species in the shrub layer were different with the increase of age class,but Dicranopteris linearis was the absolutly dominant species in the herbaceous layer at each age class.The species diversity indexes of each age class were as follows: the Patrick richness index firstly increased and then decreased with the increase of age class,and the Patrick richness index at IV age class was significant higher than that of II age class.The Shannon-Weiner index increased with the increase of age class.The Shannon-Weiner indexes at III,IV and V age classes were significantly higher than that of II age class,respectively(P<0.05),and the Shannon-Weiner index at V age class was significantly higher than that of III age class(P<0.05).The Pielou evenness index was no obvious changing trend with the increase of age class,but the Pielou evenness indexes at III,IV and V age classes were significant higher than that of age class II,respectively(P<0.05).(3)In the 0-20 cm soil layer,the ANOVA showed that there were significant differences in soil water content,field capacity,total phosphorus and p H at different age classes(P<0.05).In the 20-50 cm soil layer,there were significant differences in soil water content,field capacity,capillary porosity,total nitrogen,total phosphorus,total potassium and p H value at different age classes(P<0.05).Soil bulk density decreased while capillary water capacity,field capacity,capillary porosity,non-capillary porosity,total porosity and total phosphorus increased with age class at the same soil layer,whereas total nitrogen,available phosphorus,available potassium and soil organic matter decreased first and then increased.There was no obvious regularity of other soil indicators.The soil bulk density and p H value of different soil layers at the same age class showed 0-20 cm < 20-50 cm,while other physical and chemical indicators showed0-20 cm > 20-50 cm.(4)The correlations between soil moisture with soil bulk density,capillary porosity,total porosity as well as between total porosity with capillary porosity,non-capillary porosity reached significant or extremely significant levels.There were significant or extremely significant correlations between soil organic matter and total nutrients,available nutrients as well as between soil p H value and total nutrients.The correlations between total nitrogen,total phosphorus,total potassium and other chemical indicators all reached significant or extremely significant level,except that the correlation between total nitrogen and available phosphorus.There were significant or extremely significant correlations between soil water capacity and total phosphorus,total potassium,available nitrogen,p H value;except for available nitrogen,the correlation between soil chemical indicators and soil porosity reached significant or extremely significant level.(5)The minimum data set for evaluating soil quality including field water capacity,total nitrogen,soil organic matter,p H value,non-capillary porosity and soil bulk density was determined from soil physicochemical indicators using the principal component analysis in combination with Norm value and the correlation between physicochemical properties.It was observed that soil quality comprehensive index significantly increased along with age class at two soil depths(0-20 and 20-50 cm)(P<0.05).In addition,the soil quality comprehensive index decreased significantly with the increase of soil depth at the same age class(P<0.05),that is 0-20 cm > 20-50 cm.The redundancy analysis results showed that the main factors affacting soil quality in the 0-20 cm soil layer were the litter thickness,Shannon-Weiner index,the proportion of broad-leaved trees and understory vegetation coverage,while the main factors affacting soil quality in the 20-50 cm soil layer were the stand age,canopy density and average DBH,and soil quality was positively correlated with the these vegetation factors.