The Characteristics Of The Litter Distribution And Its Hydrological Effects Of Typical Vegetation In The Loess Hilly Region

Plant litter is an important part of the ecosystem,it provides the theoretical basis for ecological effect assessment vegetation restoration and soil erosion model improvement by studying on the characteristics of the vegetation litter distribution and its hydrological effects of typical vegetation in the Loess Hilly Region would.Eleven typical vegetations community of Robinia pseudoacacia Linn,Pinus tabulaeformis Carr,Hippophae rhamnoides Linn,Caragana Korshinskii Kom,Sophora viciifolia,Periploca sepium Bunge,Artemisia gmelinii,Bothriochloa ischaemum?L.?Keng,Roegneria kamoji Ohwi,Setaria viridis?L.?Beauv,Artemisia capillaries Thunb were selected systematically study on that the accumulation of surface litter and the amount of litter in the soil by field investigation.clarify the proportion of litter in the soil by analyzing the distribution characteristics of litter.Four typical vegetations community of Robinia pseudoacacia Linn,Caragana intermedia Kom,Artemisia gmelinii community and Bothriochloa ischaemum?L.?Keng community were selected to study the distribution of litter on the slope?ranged from 40 to 80m?and to discuss the effects of vegetation litter incorporated in soil on soil properties.Six kinds of plants?Robinia psendoacacia Linn,Pinus tabulaeformis Carr,Hippophae rhamnoides Linn,Sophora viciifolia,Artemisia sacrorum and Bothriochloa ischaemum?L.?Keng?were selected to fixed point monitoring the litter production to study the annual litterfall,litter organ composition and litter dynamics of litter for two years,in order to clarify the primary productivity of desert litter and the sustainability of ecosystem development.To study the effects of surface litter,litter in litter,litter organs and lunar debris on water holding and intercepting capacity by soaking water,in order to clarify the rainfall interception and soil and water conservation benefits of litter.Seven kinds of plants?Robinia pseudoacacia Linn,Pinus tabulaeformis Carr,Hippophae rhamnoides Linn,Caragana Korshinskii Kom,Sophora viciifolia,Artemisia gmelinii,Bothriochloa ischaemum?L.?Keng?were selected to study the water evaporation characteristics of the litter and the effects of soil moisture on Litter mixed into the soil by water evaporation test,in order to provide a theoretical basis for further research on the ecological service function of vegetation litter.The results showed that:?1?The total amount of the litter of typical plant ranged from 261.07 to 1860.69 g·m^-2,the litter in soil is widely distributed in the surface from 0 to 5 cm of each vegetation sample,accounting for 21%to 73%of the total amount of litter.The aboveground litter volume and the amount of litter incorporated in soil were 1.05 to 2.48 times and 1.04 to 1.41 times great than that in lower slope.While for the middle slope,the aboveground litter volume and the amount of litter incorporated in soil varied greatly and no significant relationship was found between middle slope and upper slope or lower slope,due to the influence of runoff scouring and the process of sediment detachment,transport and deposition.With the increasing amount of litter incorporated in soil,soil properties of bulk density,cohesive force and WAS-GMD decreased linearly?p<0.01?.For the soil organic carbon and total nitrogen content,they were increased linearly with the amount of litter incorporated in soil in grasslands?Artemisia gmelinii community and Bothriochloa ischaemum?L.?Keng community?.While no significant relationship was found in Robinia pseudoacacia Linn.plantation and Caragana Korshinskii Kom plantation.?2?The total amount of the litter production annual of typical plant ranged from 70.65to 455.57 g·m^-2,Leaves are the most important component of litter and accounted for 48 to91%.The amount of litter production per month was 1.86 to 160.21 g·m^-2 which can be divided into unimodal,bimodal or irregular modes of the annual dynamic.In general,the litterfall of arbor?Excluding Pinus tabulaeformis Carr?and shrub vegetation is mainly concentrated in the growth period,accounting for 81.50%to 89.74%of the total amount of the litter production annual,while the litter of Herbs and Pinus tabulaeformis Carr does not differ in the growth period and dormancy period.The total amount of the litter production annual accounted for ranged from 10.09 to 35.83%of the total amount of the litter of each vegetation sample,and the vegetation litter turnover period ranged from 3.79 to 10.91a.Overall,the decomposition rate of typical vegetation litter in the region was shrub>arbor>Herbs.?3?There was an extremely significant logarithmic relationship between the water?holding capacity of litter and the soaking time?R²?0.79,p<0.01?.The maximum water?holding capacity of litter in soil(ranged from 3.90 to 6.03 g·g^-1)is higher than that of surface litter(ranged from 1.56 to 2.91 g·g^-1)in varying degrees,which ranged from 1.9 to 2.5 times.However,the effective water?holding capacity of litter in the soil ranged from 0.86 to 2.07g·g^-1,and the effective water?holding coefficient?of litter in the soil ranged from 0.23 to0.50,which ranged from 41.18 to 72.94%lower than the effective water?holding coefficient?of surface litter.Litter density has a significant effect on the water?holding capacity of litter organs of each vegetation(the maximum water holding capacity ranged from 1.20 to4.35 g·g^-1,p<0.01),meanwhile the differences in specific surface area and void spaces result in different.the maximum water?holding capacity of plants litter production per month was dynamic(ranged from 1.79 to 3.95 g·g^-1),affected by the difference of litter organ components and the mixing of different organs.?4?The total interception runoff amount ranged from 2.56 to 30.73 t·hm^-2 in typical vegetation samples,the amount of the litter in the soil accounts for 14%to 78%of the interception runoff.The interception runoff amount of litter?fall of six plant species in the whole year ranged from 1.33 to 13.33 t·hm^-2,defoliation accounted for 57.19%to 86.12%of the interception of the litter in the whole year.Overall,the interception runoff amount of the litter production annual accounts for 8.84%to 52.47%of the total interception runoff amount in typical vegetation samples,vegetation maybe affects the soil and water conservation of litter in the plant samples by affecting its litter production.?5?The water?holding capacity of water-saturated litter of typical vegetation decreases with evaporation time and showed a significant exponential function?R²>0.98,p<0.01?.litter Evaporation environment has a significant effect on the evaporation rate of litter water,the maximum evaporation rate of litter under outdoor conditions ranged from 1.42 to 2.34g·g^-1·h^-1,which is significantly higher than that under indoor conditions,which ranged from3.75 to 3.64 times.At the same time,the evaporation rate of outdoor litter water gradually decreases with time,and the evaporation rate of water has a logarithmic function relationship with time?R²>0.71,n=12,p<0.01?,The evaporation rate of indoor litter moisture increases first and then decreases with time,showing a very significant exponential function relationship with time?R²>0.41,n=20,p<0.01?.?6?The incorporation of litter into the soil can significantly increase the soil moisture,the soil moisture increases by 3.18%to 19.15%compared with the control experiment.The water?holding capacity,tissue density and mixing amount in the soil of litter can significantly affect the soil water content.The soil water content increases linearly or exponentially with the maximum water holding capacity of litter and the amount of litter mixture in the soil?R²>0.94,n=6,p<0.01?,and linearly decreased with the density of litter tissue?R²=0.76,n=6,p<0.01?.In addition,the difference between the soil moisture content of the litter mixed with the soil and the water content of the bare soil increases linearly with the increase of soil water content?R²>0.16,n=25,p<0.05 or R²>0.28,n=18,p<0.01?.in the end,experimental studies on the effects of litter mixed in the soil on soil moisture in different vegetation plots show that in the environment with large evaporation,litter mixing in the soil can increase soil rainfall storage?1.75⁵.82%?,and the evaporation intensity is higher.while evaporation intensity in the smaller environment,the soil moisture loss of litter mixing in the soil is reduced by 2.30%to 10.88%compared with the soil moisture in the bare soil.In summary,the accumulation of litter is a process of accumulating year by year.There is a difference in the amount of litter cover and the amount of litter mixed in the soil between different vegetations.The influence of the process,the distribution of litter shows a strong difference along the slope.The litter in soil is widely distributed in the surface from 0 to 5cm of each vegetation sample,accounting for 21%to 73%of the total amount of litter.Litter is mainly composed of deciduous leaves,which is the main source of litter accumulation.Due to plant growth rhythm and vegetation type,litter composition and litterfall have obvious seasonal changes.Affected by litter composition,morphological characteristics and litter rhythm,there are also significant differences in water holding capacity,which in turn affects its ability to intercept.When the litter is mixed into the soil,its water holding capacity is 15.73%lower than that of the surface litter,and its runoff storage accounts for 14%to 78%of the total intercepted volume.Further,the litter into the soil can be significantly increased soil water content,compared to the bare soil,litter into the soil may increase the soil water content by 3.18%to 19.15%,and the soil water content varies with the maximum water holding capacity of the litter and The amount of litter mixture increased linearly or exponentially,and decreased linearly with the density of litter tissue.In this study,In this study,through in-depth study on the distribution of typical vegetation litter distribution,litter,water holding,impounding,evaporation and mixed surface water in the region,it is clear that the litter plays a role in rainfall interception,water conservation,and prevention of soil erosion.The important role is to provide the theoretical basis for ecological effect assessment vegetation restoration and for soil erosion model improvement on the Loess Plateau.