Characteristics Of Understory Vegetation And Soil Physicochemical Properties Of Pinus Tabulaeformis Plantation In The Southern Horqin Sandy Land

In this thesis,12 standard sample plots were established in oil pine plantations in Qinglong Mountain Forestry,Nayman Banner,at the southern edge of the horqin sandy area,and the soil was collected from 0-20 cm,20-40 cm and 40-60 cm by investigating the species name,plant number,height and cover of vegetation.The relationship between vegetation species diversity index and soil physicochemical properties was analysed using redundancy analysis.The optimum configuration was selected to provide a scientific basis for the sustainable management of oil pine plantations in sandy areas.The soil quality index method and the Nemero correction method were also used to comprehensively evaluate the quality of soil fertility in oil pine plantations under different slope orientations and stand densities,and the main conclusions were as follows:(1)The total number of species in the understorey of oil pine plantations at different slope orientations and stand densities in each sample site was 51,belonging to 21 families and 42 genera,with the highest number of species at low densities on the shady slopes.(2)The soil physical and chemical properties of oil pine plantations at different slope orientations and stand densities are analysed: soil water content tends to decrease with increasing stand density,soil bulk density tends to decrease and then increase with increasing stand density,reaching a maximum at high density;soil porosity and field water holding capacity tends to increase and then decrease,reaching a maximum at medium density,and from different slope orientations,all soil physical indicators show a trend of shady slopes > The soil physical indicators show a trend of increasing and decreasing at medium density.Soil p H increases with increasing stand density,sunny slopes > shady slopes,and reaches its maximum at high density on sunny slopes;organic matter,total nitrogen,effective phosphorus and fast-acting potassium all show a trend of increasing and then decreasing with increasing stand density,with shady slopes always greater than sunny slopes,and reaches its maximum at medium density on shady slopes;total soil phosphorus increases with increasing stand density,with shady slopes > sunny slopes,and total soil potassium content on shady slopes varies with stand density Soil total phosphorus increases with increasing stand density,shady slopes > sunny slopes,and soil total potassium content varies with stand density on shady slopes: low density >high density > medium density,while on sunny slopes soil total potassium content and soil alkaline nitrogen content show the same pattern: medium density > high density >low density.(3)The study concluded that there were significant differences(P < 0.05)in soil fertility quality between the six types of Pinus sylvestris plantation plots,and that the two methods of land fertility quality evaluation could reflect the changes in soil fertility quality of Pinus sylvestris plantation forests in terms of slope orientation and stand density.The results obtained by the two methods were consistent,concluding that the soil fertility quality of the medium-density Pinus sylvestris plantations on shady slopes was the highest and more suitable for forest management in the region.(4)The results show that there are significant differences in soil fertility quality between the six types of Pinus tabulaeformis Plantation sample plots(P < 0.05).The two land fertility quality evaluation methods can reflect the changes of Pinus tabulaeformis Plantation in slope direction and stand density on soil fertility quality.The results obtained by the two methods tend to be consistent.It is concluded that the soil fertility quality of Pinus tabulaeformis Plantation with medium density on shady slope is the highest,It is more suitable for forest management and stand density in this area.