Community Characteristics And Soil Habitat Altitude Response Of Pinus Taiwanensis In Daiyun Mountain Nature Reserve

The Pinus taiwanensis is endemic to China.There are 6400 hm2 native P.taiwanensis communities in the Daiyun Mountain National Nature Reserve,which is a typical representative of the warm coniferous forest in the subtropical high altitude region.The mesh points method is adopted in this study and an 5.7 hm2(86×25.82 m×25.82 m)of fixed sample plot was established in this P.taiwanensis communities.By investigating the community characteristics and distribution characteristics of soil factors,analyzing the response of the soil environmental at different altitudes in this P.taiwanensis communities,the conclusions are drawn as follows in this paper.There are 219 species of woody plants which belong to 59 families and 108 genera in the P taiwanensis communities of Daiyun Mountain National Nature Reserve.The dominant species of shrub layer are P.taiwanensis,Pinus massoniana,Schima superba,Oligostachyum oedogonatum,Eurya saxicola and Eurya rubiginosa.The dominant species of herb layer are Awn,Hicriopteri glauca,Gahnia tristis and Woodwardia japonica.In the type of faunal distribution,the family and genus of tropical distribution type is more than that of temperate tropical distribution type.The pantropical distribution is the main type of the tropical distribution.The north temperate distribution type occupies a large proportion in the temperate distribution type.The dominant species of P.taiwanensis communities at different altitudes are analyzed by calculating importance value of species.The conclusions are as follows:The number of dominant species which are in the tree layer at the altitude of 1300 m are more than that at the altitude of 900 m and 1000 m,but the number of dominant species are the least at the altitude of 1700 m.The number of dominant species in shrub layer are showed a decreasing trend with altitude increasing.However,the number of dominant species which are in herb layer are increasing with altitude increasing,reaching the maximum at the altitude of 1500 m and the minimum at the altitude of 900 m and 1700 m.There is little difference among dominant species in different altitudes.Among them,P.taiwanensis,Schima superba,Pinus massoniana and Cunninghamia lanceolata are the dominant species in most altitude areas.The individual number of Pinus taiwanensis are more at the altitude of 1300 m,1200 m and 1500 m,and its value importance is increased with altitude increasing,which indicates that its dominance is becoming more and more obvious.The following species are dominant at all altitudes:Oligostachyum oedogonatum,Bredia sinensis,Eurya rubiginosa,Rhododendron latoucheae and Vaccinium carlesii in the shrub layer,Dicranopteris pedata,Woodwardia japonica and Gahnia tristis in herb layer.The species diversity of P.taiwanensis communities in tree layer,shrub layer and herbaceous layer is measured by a diversity index.The Simpson index,Shannon-Wiener index and Pielou index of Pinus taiwanensis communities in the shrub and herb layers are samely increased first and then decreased with the increase of altitude,which are single peak curve.Species richness and evenness are higher in the middle altitude in the shrub and herb layers.The analysis of β diversity of altitudinal gradient pattern in Pinus massoniana community shows that dissimilarity index of community is the most at the altitude between 900 m and 1000 m,between 1600 m and 1700 m.It is double peak type.The Cody index of the tree layer is increased with altitude and the maximum an altitude of 1600 m,which is also the double peak type.The Sorensen index and Jaccard index is decreased with the increase of altitude,which indicates that the species diversity is decreased with altitude.The Cody index of shrub layer is showed a single peak with the increase of altitude,and has the greatest difference at an altitude 1600 m.The Cody index of herb layer is showed double peak with the rising of elevation and is the maximum at an altitude of 1200 m.The physicochemical properties are correlated with the altitude.There is a big difference between soil layers,The value of physicochemical properties and except for total potassium in 0～20 cm soil layer are higher than that of 20～40 cm soil layer.All kinds of indexes are inconsistent with altitude.The contents of TC,TP and OM are increased gradually with the increase of altitude.TN and AN is increased first and then decreased,reaching the maximum at the altitude of 1400 m.The difference of pH between different altitudes is not obvious,which is the largest at the altitude of 900 m.However,the variation content of TP and AP is not obvious,and the fluctuation is higher.The variation of soil physicochemical properties are less different than others.The variation of pH was the least.The available phosphorus variants belong to strong variation,and others are medium variation range.The soil was acidic.The OM of soil is rich at all altitudes,but phosphorus content of soil is deficient.There are difference of other indexes at all altitudes.PCA and DCA are used to analyze the relationship between the vegetation factors and environmental factors in P.taiwanensis communities.They are also used to quantificationally analyze the relationship between environmental factors and their effects on the spatial distribution pattern of species in P.taiwanensis communities.The cumulative contribution rate of PCA analysis is more than 80%in the 0～20 cm and 20～40cm soil layer,while it is showed different correlation at different altitudes.The results of DCA analysis shows that the four axes of cumulative explanatory rate of is 36.37%in the tree layer,40.41%in the shrub layer and 42.8%in the herb layer.At the same time,there are different correlation between dominant species and soil physicochemical factors.The contribution rate of soil physicochemical properties to tree species diversity are more at the altitude of 1300 m,900 m and 1000 m.The contribution rate to shrub species are also more at the altitude of 1100 m.There is more the contribution rate in herb layer at the altitude of 1500 m,1200 m and 1400 m.However,the contribution rate is less at an altitude of 1700 m.