Analysis Of Understory Vegetation Characteristic And Soil Physical-Chemical Properties Under Pinus Tabulaeformis Plantation In Northern Mountain Of Hebei

Plantation is widely applied in vegetation restoration in northern Hebei Province.As ecological service function of forest has become concerned increasingly,the change of local vegetation and environment during the process of afforestation are worth studying.Research is based on a study of Pinus tabulaeformis plantations at different age groups in northern mountain of Hebei.According to the results of species composition,ecological niche,species diversity which is including richness,evenness and combined index of understory vegetation,soil physical-chemical properties and the correlation with both of revives form site investigate and indoor experiment.The results are as follows:1.There were 17 families,33 genera and 39species of understory plants in the study sites,Compositae,Rosaceae and Leguminosae taken large proportion.Use stand age as resource axis to formulated niche and found out that Lespedeza juncea,Artemisia annua and Scutellaria baicalensis Georgi have a stronger adaptability due to the bigger niche breadth.Most pairs with a low overlap index in niche,highly specialized.Environment was significantly changed with growth of Pinus tabulaeformis plantation,understory community succession from mesoxerophytes to mesophytes as where from barren hills to mature plantation site.2.Richness and diversity index were both higher in Pinus tabulaeformis plantation than in barren hills,species increased with stand ages at the beginning and decreased later,Ptrick and Menhinick richness index reached a peak in young growth and immature timber respectively.Young stand stage also had bigger diversity index and evenness value.The descending order of aboveground dry biomass(ADB)were as:young stand>mature stand>immature timber>barren hills,with the range of 68.49?266.39 g/m2.3.Soil bulk density and porosity were undulately changed with increased stand ages,Pinus tabulaeformis mature stand had lowest soil bulk density and highest porosity,also with a growth-suitable proportion between capillary porosity and non-capillary.Absolute moisture contents,TN and SOC decreased first and then increased with growth of Pinus tabulaeformis stand and peaked in mature stand.pH decreased with increased stand ages totally,lead to alkaline soil turning neutral soil gradually,pH in all study site arranged from 6.53?8.23.4.Under this afforestation model,we found an extremely significantly inverse correlation between stand ages and pH value,while a significant positive correlation between growth characteristics of overstory and soil nutrient include TP,TN,SOC and moisture contents in deeper layer of soil.But there is a significant negative correlation between stand density and SOC,TN in deeper layer,though stand density was negatively correlated with bulk density of topsoil(refers to 0?20cm in this study)significantly.We also found a negative correlation between understory vegetation ADB and topsoil moisture contents,and negatively correlated with pH and bulk density significantly.ADB was positive correlated between total porosity and non-capillary porosity.All diversity indexes had a negative correlation with soil TN and SOC,specially in deeper soil layer.Evenness and Menhinick richness index were positively correlated with topsoil moisture contents,and also positively correlated between richness,diversity index and non-capillary porosity,but both negatively with capillary and total porosity.