In order to compare and analyze the impacts of stand density on hydrological and ecological functions of litter layer

the Robinia pseucdoacacia plantations with 6 different densities (475

900

1 200

1 575

1 825 and 2 350 trees/hm2) in Loess region of Western Shanxi Province were chosen as the object. By the methods of field survey and laboratory experiment

the hydrological characteristics of litter layer

such as the litter total storage capacity

the maximum water holding capacity and modified interception capacity and their relationships with soaking time

were studied

aimed to propose the reasonable density of the Robinia pseucdoacacia management in this area and provide scientific basis for giving full play to soil and water conservation functions as well as achieving function-oriented vegetation regulation and optimal allocation. The results showed that:(1) The litter total thickness of Robinia pseucdoacacia plantations with 6 densities ranged from 28.67 mm to 54.33 mm in the studied area. The total volume was about 2.98~10.65 t/hm2

and in a certain stand density

the litter total storage capacity increased first and then decreased with the increase of densities

showing an order of 1 575 trees/hm2 > 1 825 trees/hm2 > 1 200 trees/hm2 > 900 trees/hm2 > 2 350 trees/hm2 > 475 trees/hm2. (2) The maximum water holding rates varied from 295.35% to 427.84% with no obvious regularity. The maximum water holding capacity was 11.16~37.01 t/hm2 and had significant differences among some plantations with different densities

which achieved the best (37.01 t/hm2) at 1 575 trees/hm2. The water holding capacity in half-decomposed litter layers was higher than that in un-decomposed litter layers

but different stand densities had little effects on water absorption rates. (3)The modified interception capacity was about 7.22~23.64 t/hm2 in different stands and the maximum was found in 1 575 trees/hm2

reaching 23.64 t/hm2. (4) Water holding capacity of litter had a logarithmic correlation with immersion time (Q=aln t+b

R2>0.95)

and water absorption rates showed a power function with soaking time (V=ktn

R2>0.99). In summary

within the scope of this study

the litter layer showed better hydrological and ecological function under plantation with around 1 575 trees/hm2. When the density was lower than 1 200 trees/hm2

it tended to drop sharply. From the perspective of litter hydrological function

it is recommended to maintain the rational stand density range of 1 200~1 800 trees/hm2 in future Robinia pseucdoacacia plantation management of this area.