| Linpan is a natural settlement with the production,living and landscape in the Chengdu plain.It has the pattern of"forest,water,shelter and farmland".The core area covers some parts of Dujiangyan,Wenjiang,Pi Du,Chongzhou and Xindu,and is praised as the elite irrigation area,water conservation area and important ecological screen in the central part of Sichuan.Obstacles.The tree coverage rate is 43.5.%to 76.6.%,which has excellent effect on maintaining the climate stability and water system in Western Sichuan.Litter is a part of the organs and tissues of plants in plant community that are withered and returned to the soil due to death.As the general term of decomposition and consumer materials and energy sources,litter,litter,skin,litter reproductive organ and dead root system are one of the important factors affecting forest ecosystem.Litter covering the surface can inhibit soil evaporation,improve the land properties,increase precipitation infiltration,prevent soil erosion and enhance the soil erosion resistance.The litter of the typical trees in the forest pan of Western Sichuan Province was selected as the research object.The litter produced by 8 main trees(Bambusa emeiensis?Lindera megaphylla?Broussonetia papyrifera?Pterocarya stenoptera?Ginkgo biloba?Metasequoia glyptostroboides?Cinnamomum camphora?Phyllostachys violascens Prevernalis')were collected through field investigation.The time and space decline came to the end,and the water holding capacity and rainfall retention capacity were measured and calculated in the laboratory.The litter layer and soil were analyzed by comparison and analysis.The difference of soil surface water holding capacity,the ability of litter to store rainwater and the effect of litter on improving soil physical and chemical properties were explored,which provided scientific basis for the protection and restoration of traditional forest disc in We s t e r n S i c h u a n.T h e s p e c i f i c r e s e a r c h r e s u l t s a r e a s f o l l o w s:(1)Litter in forest disc is widely found in soil layer(0-5 cm)of various trees.The total litter accumulation of 8 typical tree plots is 251.48-2302.94 g·m-2.The litter mixed in soil accounts for only 3.28-36.72.%of the total litter accumulation,and the surface litter storage is significantly greater than that of mixed soil.The total litter accumulation of the selected typical trees was as follows:Pterocarya stenoptera.>Bambusa emeiensis.>Broussonetia p a p y r i f e r a.>C i n n a m o m u m c a m p h o r a.>G i n k g o bi l o b a.>M e t a s e q u o i a glyptostroboides.>Phyllostachys violascens Prevernalis'.>Lindera megaphyllal.(2)The annual litter of 8 typical tree plots in the forest disc is 159.16-2116.9 g·m-2,which is the main component of all kinds of tree litter;the itter is 0-672.84 g·m-2per month g·m-2,due to the differences in the litter period of various trees,presents the dynamic characteristics of double peak,single peak and irregular type.At the same time,the annual litter dynamics of all kinds of trees show three stages,namely,the peak period,the stable period,and the intermittent period.(3)The results show that the litter in 8 typical tree plots in the forest disc has a significant influence on the soil physical and chemical properties.Compared with the alkali nitrogen content in 8 tree samples in spring and autumn,the results show a consistent seasonal change,which is generally shown as:spring(136.79-298.92mg·kg-1)>autumn(18.84-112.79 mg·kg-1)?The content of alkali dissolved nitrogen and available phosphorus decreased linearly with the increase of litter mixing(before decomposition),while the content of available potassium in soil was not significantly correlated with the amount of mixed(P>0.05,n=8).The results showed that litter had a seasonal lag in the improvement of soil nutrients.(4)The surface effective water holding capacity of 8 typical tree litters in the forest tray ranged from 2.39 g·g-1to 3.47 g·g-1.The effective water holding capacity of litter in soil ranged from 3.28 g·g-1to 5.06 g·g-1.The relationship between litter water holding capacity and soaking time was positive correlation.The results showed that the water absorption rate of surface litter layer and mixed soil litter layer was similar with time.The water absorption rate of litter layer reached the peak at 5 min of rainfall,and decreased with the increase of soaking time.(5)The total amount of litter interception was 5.38?59.93 t·hm-2in 8 typical arbor plots,and the runoff interception capacity of litter in different arbor soils accounted for 1.44?24.16.%of the total interception capacity.The mean value of surface litter interception was deciduous tree(28.27 t·hm-2)>evergreen tree(19.35 t·hm-2),while the mean value of soil litter runoff interception was just opposite to the surface,deciduous tree(1.87 t·hm-2)<evergreen tree(2.29 t·hm-2).The runoff retention capacity of litter in four seasons was summer>autumn>winter>spring. |
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