Hydrological effects of litter layer under different vegetation types on the eastern slope of the Helan Mountains
Seven vegetation types on the eastern slope of the Helan Mountains in Ningxia were selected to study the hydrological effects of litter layer by means of field investigations and indoor experiments,aiming to explore the differences in the water-holding capacity of litter layer in different vegetation types and decomposition layers.The results showed that:(1)Across different vegetation types,the amount of litter stock ranged from 1.56 to 60.78 t· hm-2,and the maximum water-holding capacity of litter ranged from 6.34 to 10.91 t·hm-2.The maximum water-holding capacity ranged from 126.8％to 199.1％,and the maximum retention rate ranged from 125.0％to 190.4％.The effective retention rate ranged from 105.9％to 160.6％.The effective storage volume ranged from 2.59 to 15.22 t·hm-2.For different decomposition layers,litter stock ranged from 12.19 to 71.60 t·hm-2,the maximum water-holding capacity of litter ranged from 4.91 to 10.16 t·hm-2,the maximum water-holding rate ranged from 112.5％to 207.3％,the maximum storage rate ranged from 104.0％to 193.8％,the effective retention rate ranged from 87.1％to 162.7％,the maximum retention capacity ranged from 2.41 to 53.14 t·hm-2,and the effective retention capacity ranged from 2.00 to 44.65 t·hm-2.(2)The stock,maximum retention,and effective retention of litter showed a relatively consistent pattern among different vegetation types,with the largest amount in Picea crassifolia forest,Pinus tabuliformis forest and mixed forest,and the largest amount in decomposed and semi-decomposed lay-ers among different decomposition layers.(3)The water-holding capacity and water loss of different decomposing layers of different vegetation types showed significant logarithmic function relationships(P＜0.01),and the water uptake rate and water loss rate showed significant power function relationships(P＜0.01)with the immersion time and water loss time,respectively.A comprehensive comparison of water retention capacity of litter in different de-composition layers of the seven vegetation types showed that water retention capacity of litter was strongest in three types of tree conifer forests,i.e.Picea crassifolia forest,Pinus tabuliformis forest,and mixed forest with those two species,and the water retention capacity of decomposed and semi-decomposed layers was strongest.Taken together,water retention capacity of litter in the region obviously differed among different vegetation types and decomposition layers.
eastern slope of the Helan Mountainsvegetationdecomposition layerlitter hydrological effect
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