| Litter is the main medium of material and energy in forest ecosystem,through provide the main material for forest organic and return nutrients to the forest to maintain soil fertility,therefore,litter has vital significance to sustainable development of soil nutrients in forest.As one of the main shrub species,caragana plantations had been an large plant in Loess Hilly region,it is vital significance to plant and manage the caragana plantation through research the characteristic of caragana litter to further understand the structure and the function of the plantation forest. The experiment started from October 2009,select plant caragana of different aspect and forest age as the subject of study,S.viciifolia natural forests as the adjoining tree,study growth factors on the plantation,litter number,litter composition,litter nutrient content and monthly dynamic,nutrient return,the results show:(1)Caragana age from 11a to 41a,range of plant height between 1.73m to 2.03m of caragana in shady slope,branch numbers are 12 to 22,stem of every branches range from 14.16mm to15.25mm;the corresponding range of sunny slope in caragana is respectively 1.29m to 1.78m,8 to 17 branch,11.87mm to 16.11mm,with the increase of forest age the crown diameter all become decreased of two aspect. With the increase of forest age,various growtn parameters of caragana were all increased firstly then decreased,it can be seen that caragana of some age were started to degradation. Total weight of leaves per unit area of seasonal growth showed doublt type in caragana of different forest age,the first peak in late May to early June,leaves accounted for about 40% of whole plants. Another peak appear in late August to early September. The new branch length of caragana increasd with the month rising,comparing the caragana of branch length in two aspect,the seasonal variation of same age in sunny slope lag behind the shady slope.(2)From 11a to 41a,litter production of plant caragana forest in sunny slop respectively was 1230kg/hm~2,1298kg/hm~2,987kg/hm~2 and 721kg/hm~2,corresponding,litter production of sunny slope respectively was 1288kg/hm~2,1997kg/hm~2,1187kg/hm~2 and 1069kg/hm~2. Litter production of S.viciifolia natural forests was 2094kg/hm~2.variance analysis of different aspect and forest age caragena showed that forest age and aspect have an important impact on litter production of caragana. In the composition of the various components of litter,leaves dominate advantage,followed by other components,litter production of branch and fruit is less,flower account for the least amount of litter. Monthly change of the amount of caragana forest litter are mostly double peak in sunny slope,and bimodal ppattern in shady slope. The main peak appeared in 8 to 10 months. compared with caragana forests,monthly change of the amount of S.viciifolia natural forests is double type,peak occurred in May and October,litter production of 9 or 10 month is the main litter period account for 56% of the total amount of litter.The order of litter nutrient content in different slope and age caragana are all N﹥K﹥P. However,the oreder of nutrient cotent in each component were different.Monthly change pattern of nutrient content in 4 age of caragana mainly were double and multimodal. the peak of nutrient content in same components of different age were different.(3)The size of nutrient return in every component of different slope and age caragana are expressed as N﹥K﹥P. S.viciifolia is still followed this rule. Compositing the nutrient return of 3 elements can be found that 18 age caragana of the two slope and S.viciifolia natural forests have similar nutrient return,to some extent,caragana can provide more nutrients to the soil. To the nutrient return of litter components,leaves accounted for a large proportion of the return,almost to reach 50% of the total return amount. The return of Other components and flowers next to leaves,nutrient return of fruit and branch accont for relatively small number, different age have small difference about specific changes. Monthly change pattern of nutrient return of every components were different in different aspect and age,there are single,double and three peak models. Monthly change pattern of every component in different age caragana is different, the same aspect and the same component but different age has the same monthly change pattern,only some litter component has different monthly change,but the distribution of peak month remains the same. Monthly change pattern of nutrient return in different aspect and same age between every component is distinct,the same component has the same monthly change pattern,the peak month remain the same. So aspect and stand age can affect the amont of each component,but has a little influence on the monthly change pattern in same component.(4) From biomass live weight, litter production, nutrient content and nutrient return in litter we may find that with the increase of stand forest indicators mostly first increasing and then decreasing. Caragana of 18 age are close to S.viciifolis forest. Caragana of 31 stand age is stable develop in stable state. 11 age has volatile and 41 age is lower in every indicator. In the process of whole develop about caragana,caragana of 41 stade age in a degraded condition. Shady slope is better than the sunny slope.in variety growh and litter indicators of different aspect and same age. |
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