Characteristics And Evaluation Of Soil Ecological Environment Under Different Mixed Forest Patterns In Hilly Area Of Southern Ningxia

In order to screen out the most suitable mixed forest patterns in hilly area of Southern Ningxia,this paper took four different plantation patterns(peach × pinus tabulaeformis,larch × pinus tabulae form is,aspen × larch and larch)in the Camel forest basin of Liupanshan Mountain in Ningxia as the research object,and took wasteland as the control,the soil property litter and soil water-holding capacity as well as the ecological niche characteristics of vegetation in different mixed forest patterns were explored through the method of combination of fixed-point sampling and laboratory experiments,so as to provide theoretical basis for ecological construction in hilly area of Southern Ningxia and promote local ecological restoration.The main conclusions are as follows:(1)The plantation forest had the greatest effect on the soil bulk density porosity in the 0-10cm soil layer,and the pure larch forest had the best effect on improving the soil bulk density porosity,while larch × pinus tabulaeformis significantly increased the soil bulk.Four plantation patterns could significantly increase the number of macroaggregates in soil and improve the stability of soil,among peach × pinus tabulaeformis had the most significant effect on improving aggregates.With the deepening of soil layer,soil bulk density increased,porosity decreased,and the number of large aggregates decreased sharply,among peach × pinus tabulaeformis the maximum reduction was 24.93%;(2)Soil nutrients and enzyme activities were significantly different under different patterns.The content of ammonium nitrogen in the mixed soil containing broad-leaved tree species was twice that in the wasteland,and the highest content of organic matter and available potassium in the mixed soil containing peach × Pinus formulaeformis was more than three times that in larch.larch × pinus tabulaeformis and larch pattern total phosphorus available phosphorus and alkaline phosphatase activity is higher,because there are more herbaceous plants in wasteland with strong nitrogen fixation,the total nitrogen content is higher.With the deepening of soil layer,soil available nutrients and enzyme activities decreased significantly,but pH conductivity catalase activity had little change;(3)Soil microbial biomass carbon and nitrogen contents of peach x pinus tabulaeformis were significantly higher than those of other patterns,with the deepening of soil layer,except for larch ×pinus tabulaeformis,the soil microbial biomass carbon and nitrogen content under other patterns decreased by more than 50%.The soil fungal diversity of wasteland was significantly higher than that of plantation,and the soil fungal diversity of larch was the lowest,basidiomycota and Ascomycota accounted for the largest proportion in each pattern.With the deepening of soil layer,the abundance and evenness of soil fungi decreased,soil nitrate nitrogen available potassium urease alkaline phosphatase in 0-20cm soil layer has a significant correlation with soil fungal diversity index,soil total nitrogen nitrate nitrogen in 20-40cm soil layer has a significant correlation with soil fungal diversity index;(4)Water holding capacity of litter size:aspen × larch>larch>larch × pinus tabulaeformis>peach × pinus tabulaeformis,soil water storage capacity of different models was different in the 0-10cm soil layer,and there was little difference in the soil layer below 10cm,and larch soil had the strongest water storage capacity.From the perspective of vertical distribution of soil water,it decreased with the soil depth deepening,and the maximum change occurred in the 0-20cm soil layer,the soil water content in the peach × pinus tabulaeformis soil layer was higher,and the soil water activity was higher.From the perspective of seasonal distribution of soil moisture,soil moisture accumulation is obvious,and the peak value of soil moisture is consistent with the peak value of rainfall.When the rainfall is less than 100mm and greater than 220mm,the moisture content of deep soil may exceed that of shallow soil;(5)From the perspective of niche characteristic values,the mixed pattern of peach × pinus tabulaeformis among the trees was the most reasonable for the utilization of resources;while the herbarium trigonum appeared in various mixed patterns with niche widths above 0.65,showing the strongest adaptability to the environment and being the dominant species;(6)Using analytic hierarchy process(AHP)and entropy value method are peach × pinus tabulaeformis is the better mixed pattern to improve the local soil ecological environment,combining the above two methods of five kinds of mode using subjective and objective comprehensive evaluation method of soil ecological environment situation sorted result for peach × pinus tabulaeformis>aspen ×larch>larch>wasteland>larch × pinus tabulaeformis.In conclusion,the mixed pattern of peach ×pinus tabulaeformis has the better improvement effect on soil ecological environment.