Study On The Distribution Of Fine Roots And Soil Water Consumption Characteristics Of Typical Artificial Forest Lands In Loess Hilly Region

Dried soil layer is common in plantation vegetation on the Loess Plateau,which causes the deterioration of eco-hydrological environment.The deep roots of trees in arid areas are the main channels of water and nutrient absorption and maintain the transpiration,evaporation and growth of vegetation.In particular,fine roots are responsible for obtaining nutrients and water from the soil to support the growth and survival of plants.It is of great significance to study the characteristics of deep soil water utilization of plantation vegetation and forest land on the Loess Plateau to clarify the distribution rules of fine roots.Sampling is difficult due to deep soil layers,leading to a deep loess plateau plantation fine root distribution is not very clear,this article selects a typical loess plateau climate and typical vegetation in the study area,from south to north in turn to select a typical study area(Changwu,Ansai,Suide)in nearly 30 years of forest age of plantation vegetation as the research object,analysis within 0?10 m soil depth,The distribution characteristics of deep fine roots,the variation of soil water and the consumption degree of soil water storage in two plantations.The main research conclusions are as follows:(1)The distribution characteristics of deep fine roots of Robinia pseudoacacia and Pinus tabulaeformis were clarified.There were significant differences in the vertical distribution depth of fine root biomass in different areas,with the maximum in Ansai and the minimum in Changwu.The relationship between surface area and root length density of deep fine roots was power function with soil depth.The main distribution range of fine root surface area of Robinia pseudoacacia forest(cumulative fine root surface area accounted for 80%)was 0?6.0m(Changwu),0?7.6 m(Ansai)and 0?7.8 m(Suide),respectively.The fine root surface area of Pinus tabulaeformis forest was 0?3.4 m,0?6.8 m,0?4.4 m.The surface area and density of fine root length in semi-arid area(Ansai and Suide)were significantly lower than those in semi-humid area(Changwu).(2)The vertical distribution characteristics of soil water in deep layer(below 100 cm)of Robinia pseudoacacia and Pinus tabulaeformis plantations on the Loess Plateau were clarified.The deep soil water content in Ansai and Suide plantations was lower than 8%,and it was not obvious with the increase of soil depth.The soil moisture content in the deep layer of Changwu is higher than 10% and increases with the increase of soil depth.The deep soil water content of Robinia pseudoacacia forest is less than that of Pinus tabulaeformis forest,and the difference between them increases with soil depth.(3)The soil water storage and deep soil water consumption of artificial forest land were analyzed.The deep soil water storage of Pinus tabulaeformis forest in 0-10.0 m depth was significantly higher than that of Robinia pseudoacacia forest.The difference of water storage between the two plantations was the largest in Changwu,followed by Suide and the smallest in Ansai.The deep water consumption and deep water consumption rate of Robinia pseudoacacia and Pinus tabulaeformis in semi-arid area were significantly higher than those in semi-humid area.The soil water deficit within 1-10 m depth of Robinia pseudoacacia forest land in Changwu,Ansai and Suide was 4.88%,42.55% and 46.47%,respectively.The soil water deficit in 1-10 m depth of Pinus tabulaeformis forest land was-27.34%,36.15% and33.68% in Changwu,Ansai and Suide,respectively.(4)The correlation between deep water consumption of Robinia pseudoacacia and Pinus tabulaeformis forest and fine root distribution was explored.There was a significant positive correlation between deep water consumption and fine root surface area and root length(P<0.05).The deep water consumption of Robinia pseudoacacia was significantly positively correlated with the vertical distribution depth of fine roots(P<0.01),and the deep soil water consumption of Pinus tabulaeformis was significantly positively correlated with the vertical distribution depth of fine roots(D50,D95,?)(P<0.01).The deep water consumption of Robinia pseudoacacia was significantly positively correlated with the surface area and root length of fine roots(P<0.05),while the deep water consumption of Pinus tabulaeformis was negatively correlated with the characteristic value of fine roots.