Effects Of Root Channels In Forest,Shrubland,and Grassland On Soil Water Infiltration

In arid and semi-arid regions,the relationship between plant growth and soil moisture is seriously out of balance due to water limitation and human interference,which lead to vegetation degradation and death.During the process of vegetation degradation and death,decayed root systems can form preferential channels.Preferential channels are conducive to soil water infiltration and are of great significance to the replenishment of soil water in arid and semi-arid areas.In order to explore the influences of root channels of typical vegetation types on the Loess Plateau on soil water infiltration,we studied artificial Armeniaca vulgaris(A.vulgaris)forest,Caragana korshinskii(C.korshinskii)shrubland and Medicago sativa(M.sativa)grassland in semi-arid areas on the Loess Plateau.The soil infiltration rate and root channel paths were measured and traced by using double-ring infiltrometer and dye tracing.Changes in soil physical properties and soil infiltration rate,and the effects of root channel characteristics on soil infiltration rate were analyzed.The main conclusions were as follows:(1)Compared with bare land,A.vulgaris forest,C.korshinskii shrubland,and M.sativa grassland obviously changed soil physical properties.Compared with that of bare land,soil bulk density of A.vulgaris forest,C.korshinskii shrubland,and M.sativa grassland decreased by 2.66%,5.41%,and 8.12%,respectively.Soil porosity of A.vulgaris forest,C.korshinskii shrubland,and M.sativa grassland increased by 6.73%,7.26%,and 7.23%,respectively.Forests,shrubs,and grasses can significantly reduce soil bulk density and increase soil porosity,thus improving soil physical properties.(2)Decayed root channels of A.vulgaris forest,C.korshinskii shrubland,and M.sativa grassland significantly enhanced soil infiltration rate,soil infiltration rate was in the order of C.korshinskii shrubland > A.vulgaris forest > M.sativa grassland.Soil infiltration rates of C.korshinskii shrubland,A.vulgaris forest,and M.sativa grassland were 2.61,2.11 and 1.34 times higher than that of bare land,respectively.Root channels are the main component of soil water infiltration in the studied forest,shrubland,and grassland,they can affect the rainfallsoil water conversion process in arid and semi-arid areas,and improve the soil water condition in arid and semi-arid areas.(3)Root channels formed by the decayed roots in the forest,shrubland,and grassland were the main preferential channels in the soil.From the perspective of infiltration depth,the infiltration depth of A.vulgaris forest,C.korshinskii shrubland,and M.sativa grassland increased by 27.95%,129.16%,and 43.72%,respectively,compared with that of bare land,indicating that the presence of preferential channels significantly increases the amount of water infiltration within the same infiltration time.Decayed root systems are the main preferential channels in forest,shrubland,and grassland soil,they contribute to soil water supply,and are the main factor affecting the process of soil hydrological cycle in arid and semi-arid areas.(4)Steady infiltration rate was significantly positively correlated with the diameter and area of root channels in forest,shrubland,and grassland,for which the coefficients of determination of steady infiltration rate and root channels diameter were 0.835,0.899,and 0.709,respectively.The coefficients of determination of steady infiltration rate and the area of root channels in forest,shrubland,and grassland were 0.853,0.691,and 0.894,respectively.The effect of roots on soil infiltration rate was mainly related to the diameter and area of root channels.Root channels in the forest,shrubland,and grassland significantly improved soil infiltration rate,and soil infiltration rate followed the order of C.korshinskii shrubland > A.vulgaris forest > M.sativa grassland.Root channels formed by decayed root are the main factor affecting soil water infiltration,they are conducive to improving the utilization efficiency of soil water resources.A higher infiltration rate increases the replenishment of soil water by precipitation.Our results can provide a theoretical basis for efficient utilization of water resources in arid and semi-arid areas,and are of important guiding significance for vegetation restoration and soil water sustainability in arid and semi-arid areas.