| For unique natural condition,due to natural conditions and anthropogenic disturbance factors,soil and water loss is serious in the red soil hilly regions of South China.For a long time,serious soil and water loss was the main factor which restricted the economic development of Changting County Fujian Province,which is a typical representative of red soil erosion area in South China.After years of research and restoration by scholars and governments from all aspects,the work on water and soil erosion in Changting County achieved great success with water and soil erosion under control effectively.And to a certain extent,the vegetation condition was improved.Airplane was used to spread seeds of Pinus massoniana during early vegetation restoration.So it formed preliminary control area of water and soil erosion mainly covering with Pinus massoniana which has the disadvantages,such as simple structure of forest,low vegetation species diversity,serious water and soil loss,low ecological function etc.Therefore,it is urgent to find out how to further consolidate the achievement of water and soil loss control through the transformation of Pinus massoniana forest in the preliminary treatment of water and soil loss area of Changting to enhance the ecological function becoming a key topic of ecological mitigation construction.Many studies showed that it is an impotant forest management to interplant broad-leaved trees for overall ecological service functions which include changing the forest stand levels rapidly,restoring vegetation diversity,reducing water and soil loss,and even improving soil properties,water conservation and microclimate in the forest.However at present,there are few results in the research area.So far,there are no suitable tree species and restoration modes for the transformation of the Pinus massoniana Forest.In view of this,in this study,Pinus massoniana was chose for research object in the severe eroded red soil area developed from granite rock.This study set the comparison test in the Luhu Lake Village Hetian town of Changting County Fujian Province.On the ground of research on broad-leaved tree species in Changting County,in this study six kinds of broad-leaved trees including Vernicia fordii,Michelia maudiae,Liriodendron chinense,Sapindus mukorossi,Sylvestral elaeocarpus,Liquidambar formosana were chose to set different interplanting modes for the Pinus massoniana forest.The growth of trees,soil physicochemical properties,vegetation species diversity,water conservation and microclimate were measured in different interplanting modes.Each indexes between interplanting broad-leaved trees modes and pure Pinus massoniana forest were compared and analyzed the enhancing effect of ecological function of Pinus massoniana forest in different interplanting broad-leaved trees modes.Finally correlation analysis,cluster analysis and principal component analysis and other methods were carried out with composite indicators to choose optimal broad-leaved trees and interplanting mode which were fitable for preliminary controled soil eroded area,providing basis for promoting ecological function of Pinus massoniana forest in red soil eroded area of Changting County and South area.The results were as follows:(1)Soil physical property in surface layer(0-20 cm)was mainly affected by early interplanting broad-leaved trees.The change of soil physical properties in 20-40 cm and 40-60 cm soil layers were not significant.Comparing with pure Pinus massoniana forest,soil pore structure,water holding capacity and bulk density in different interplanting broad-leaved trees modes were better.(2)Comparing with pure Pinus massoniana forest,except Pinus massoniana mixed Liquidambar formosana in 20-40 cm soil layer,the total P contents of all soil layers in different interplanting broad-leaved trees modes were higher than in pure Pinus massoniana forest.Total P contents of all soil layers in Pinus massoniana mixed Michelia maudiae were highest in all modes.In 0-20 cm soil layer,available K and available P content in interplanting broad-leaved trees modes were higher than pure Pinus massoniana forest,but no significant discrepancy in other soil layers.There were no significant difference in pH,nutrients content,soil dissolved organic carbon(DOC)and soil dissolved organic nitrogen(DON)in each layer between interplanting broad-leaved trees modes and pure Pinus massoniana forest.(3)The DBH and tree height of Pinus massoniana in six interplanting broad-leaved trees modes was higher than in pure Pinus massoniana forest,but there was no significant difference in canopy crown.After 3 years of interplanting,vegetation biomass on the ground in different interplanting broad-leaved trees modes were significantly more than in pure Pinus massoniana forest.Among all modes,Pinus massoniana mixed Sapindus mukorossi had the largest biomass in canopy layer 10.71t/hm2.Pinus massoniana mixed Sylvestral elaeocarpus had the largest biomass in understory vegetation layer 1.83 t/hm 2.Pinus massoniana mixed Michelia maudiae had the largest biomass in litter layer 2.71 t/hm2.(4)The species diversity,richness and degree of homogeneity in both herb layer and shrub layer of interplanting broad-leaved trees modes were higher than in pure Pinus massoniana forest.The species diversity and degree of homogeneity in Pinus massoniana mixed Sylvestral elaeocarpus in herb layer were the highest among all modes.The species diversity and richness in Pinus massoniana mixed Michelia maudiae in shrub layer were the highest among all modes.But the differences of species diversity,richness and degree of homogeneity in both herb layer and shrub layer were no significant differences among all modes.(5)Interplanting different broad-leaved trees improved microclimate.The air and soil moisture in interplanting broad-leaved trees modes were higher than in pure Pinus massoniana forest,but no significant differences on the air and soil temperature.The difference of soil temperature between day and night during August and September of interplanting broad-leaved trees modes were higher than in pure Pinus massoniana forest,but no discrepancy on the soil temperature between day and night from October to December.(6)Except Michelia maudiae,the effective water conservation rate of other five broad-leaved trees’ branches and leaves were higher than Pinus massoniana’s.Interplanting broad-leaved trees could improve the effective water conservation rate in understory vegetation layer.The effective water conservation rate of understory vegetation layer including Pinus massoniana mixed Vernicia fordii,Pinus massoniana mixed Michelia maudiae,Pinus massoniana mixed Liriodendron chinense,Pinus massoniana mixed Sapindus mukorossi,Pinus massoniana mixed Sylvestral elaeocarpus,Pinus massoniana mixed Liquidambar formosana were respectively 1.29、1.15、1.35、1.37、1.14、1.2 times as in pure Pinus massoniana forest.Except Pinus massoniana mixed Liriodendron chinense,the effective water conservation rate in litter layer in other interplanting broad-leaved trees modes were higher than in pure Pinus massoniana forest.(7)Using principal component analysis and comparing the indexe of soil physicochemical properties,vegetation growth and diversity,temperature and humidity of soil and air in forest and water conservation etc,we got the order of scores for different modes:Liriodendron chinense mode>Sapindus mukorossi mode>Michelia maudiae mode>Vernicia fordii mode>Liquidambar formosana mode>Sylvestral elaeocarpus mode>Pinus massoniana forest with comprehensive evaluation on ecological function among all modes.Interplanting Liriodendron chinense,Sapindus mukorossi and Michelia maudiae were optimal on Pinus massoniana ecological function promotion. |
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