Study On The Vegetation Characteristics And Soil Physical And Chemical Properties Of Typical Artificial Forests In Dalat Banner

Land desertification is a major environmental problem facing today’s society,and the scarcity of water resources,ecological degradation and low soil productivity in desertified areas have brought extremely serious and bad effects to human society.While biological measures have a certain effect on desertification control,the vegetation configuration problem has also become a research hotspot.In this thesis,four configurations of lemon plantation in Dalat Caragana forest:N1(2661 plants·hm^-2),N2(1898 plants·hm^-2),N3(1222 plants·hm^-2),N4(736 plants·hm^-2)and four configurations of Salix plantation:S1(2258 plants·hm^-2),S2(1551 plants·hm^-2),S3(1164 plants·hm^-2),and S4(890 plants·hm^-2),respectively,were investigated for each understory vegetation,and soil was collected to investigate the correlation between understory vegetation diversity and soil physical and chemical properties indexes,and to evaluate and analyze the comprehensive quality condition of the sample plots,with a view to selecting the optimal configuration.The main findings are as follows:（1）The lemon plantation was dominated by Asteraceae and Leguminosae.The plant diversity indices were N3>N4>N2>N1>CK,except for the Pielou evenness index,which did not vary significantly between samples（P<0.05）.Salix plantations were dominated by grasses and Asteraceae.The plant diversity indices were S4>S3>S2>S1>CK,except for the Pielou evenness index,and the Pielou evenness index did not vary significantly among samples（P<0.05）.（2）Soil water content increased with decreasing stand density,while the change in bulk weight was not significant（P<0.05）,while soil water holding capacity and porosity showed a trend of increasing and then decreasing,reaching the maximum under N3 configuration.Soil chemical indicators such as total nitrogen and phosphorus showed a trend of increasing and then decreasing with decreasing stand density,reaching a maximum under N3 configuration.Soil water content increased with the decrease of stand density,and the change of bulk weight was not significant（P<0.05）,while soil water holding capacity and porosity showed an increasing trend and reached the maximum under the S4 configuration.Soil chemical properties such as total nitrogen and phosphorus tended to increase with decreasing stand density,reaching a maximum in the S4 configuration.（3）The Shannon-Wiener diversity index of Caragana plantation was positively correlated with alkaline nitrogen,and the Simpson dominance index was positively correlated with saturated water holding.Pielou Unievenness index,saturated water holding,field water holding and soil bulk density,while Margalef richness index showed a positive correlation with alkaline nitrogen and total potassium.The diversity of Shannon-Wiener with whole phosphorus,total potassium and organic matter with the field water holding;Simpson dominance index has positive correlation with whole phosphorus,total potassium,total nitrogen,organic matter and porosity,and little correlation with the field water holding;Margalef richness index and Pielou uniformity index have no obvious rules among several configurations.（4）There were significant differences in understory vegetation diversity and soil physical and chemical properties between the two different configuration vegetation plantations in the study area（P<0.05）.According to the correlation analysis of principal components and grey,the comprehensive ranking of vegetation diversity in Caragana plantation was N3（0.76）>N2（0.53）>N4（0.41）>N1（-0.63）>CK（-1.06）,and the comprehensive ranking of soil physicochemical properties was N3（1.99）>N4（1.25）>N2（0.95）>N1（-0.38）>CK（-3.81）.However,the vegetation diversity of S4（0.80）>S3（0.64）>S2（0.22）>S1（-0.60）>CK（-1.06）,and the comprehensive order of soil physicochemical properties was S4（2.33）>S3（0.85）>S2（0.28）>S1（-0.28）>CK（-3.19）.The two combinations show that N3 and S4 configuration have the best comprehensive performance under underforest vegetation restoration and soil physical and chemical properties,which is more suitable for forest forest density in this area.