| The relationship between forest and water is one of the hot issues in the study of forestry,hydrology and ecology,and the eco-hydrology function is the most important part of forest ecosystem research.Liupan mountains in Ningxia,located in the transition zone from arid and semi-arid zones to the sub-humid zones,which is one of the most abundant vegetation coverage,biological diversity runoff and forest resources regions and is known as"Green Island"and"Wet Island"in the Loess plateau.It is of special importance for maintaining regional water supply security and ecological balance.At present,the research on forest ecological and hydrological functions is mostly focused on different vegetation types and densities,and relatively few studies are made on the comparison of slope positions.In this paper,the the eco-hydrology function of Larix principis-rupprechtii forests was studied by combining field observation with indoor experiment.The difference of larix principis-rupprechtii plantation of different slopes(uphill,mid-uphill,middle,mid-downhill and downhill slope)was analyzed by observing larix principis-rupprechtii plantation of different slopes.The precipitation effect of larix principis-rupprechtii plantation in different slopes,the water-holding capacity,water-storage and permeability of water were measured,and the eco-hydrology function of different slopes was analyzed by comprehensive coordinate method.The aim of this paper is to reveal the difference of water conservation function of larix principis-rupprechtii plantation in different slopes and to provide a basis for improving the comprehensive management of water.(1)We observed 21 rainfalls in the experimental area.Total rainfall was 505.9mm,which was distributed between 1 mm~82.2 mm with a vast range of distribution.There were 5 light rain,9 moderate rain,4 heavy rain and 3 storms.The rainfall in this area is among 23.9 mm,123.5 mm,134 mm and 224.5 mm respectively,which accounts for the total rainfall of 4.7%,24.4%,26.5%and 44.3%.(2)The forest of stemflow of different slopes is different,in descending order.Middle>uphill>mid-downhill>downhill>mid-uphill slope.There is a positive linear correlation between the forest rainfall and quantity of stemflow in different slopes,whose correlation coefficient is above 0.83.With the increase of rainfall outside the forest,the quantity of stemflow also increases.The range of the rate of canopy interception is between 20.19%and 24.44%,uphill>mid-downhill>mid-uphill>downhill>Middle slope.(3)From the decomposition level of litter,Semi-decomposed lever in each slope is greater than un-decomposed lever,whose thinness and forest stock volume range between 16.41~20.42 mm and 5.02~9.42 t/hm~2.There was logarithmic correlation(Q=aln(t)+b)between water-holding capacity and soaking time of the litter in different slopes,the correlation coefficient of fitting is above 0.90.There exists a power relationship(V=kt~n)between the water absorption rate and the soaking time,the correlation coefficient of fitting is above 0.86,whose correlation is significantly good.(4)The average of soil bulk density in different slopes between 1.0 g/cm3and1.12g/cm3,the size of which is uphill(1.12 g/cm3)>downhill(1.05 g/cm3)>mid-downhill(1.04 g/cm3)>Middle(1.03 g/cm3)>mid-uphill slope(1.0 g/cm3).The average of soil total porosity percent is between 37.84%and 43.56%,the size of which is downhill(58.09%)>mid-downhill(56.25%)>Middle(56.04%)>mid-uphill(55.81%)>uphill slope(47.33%).The porosity of soil non-capillary ranges from 9.5%and 17.81%,the size of which is downhill(17.81%)>mid-downhill(15.67%)>mid-uphill(14.72%)>Middle(14.28%)>uphill slope(9.50%).Soil Saturation Water Storage Capacity is between 471.25 mm and 571.79 mm,the order of which is downhill(571.79 mm)>Middle(569.27 mm)>mid-downhill(557.14 mm)>mid-uphill(552.56 mm)>uphill slope(471.25 mm).The variation range of soil infiltration rate is between 3.97 mm/min and 8.12 mm/min,the size of which is downhill(8.12 mm/min)>mid-uphill(6.67 mm/min)>mid-downhill(5.44 mm/min)>Middle(4.94 mm/min)>uphill slope(3.97 mm/min).The variation range of soil steady infiltration rate is between 2.71 mm/min and 3.81 mm/min,the size of which is downhill(3.81 mm/min)>mid-uphill and mid-downhill(3.51 mm/min)>Middle(3.21 mm/min)>uphill slope(2.71mm/min).the change characteristic and the initial infiltration rate are more consistent.(5)The coordinate comprehensive evaluation method is used to calculate that the size of the eco-hydrology function of Larix principis-rupprechtii forests in different slopes in the northern area of liupan mountains in Ningxia is different,the size of which is mid-downhil(0.1783)>downhill(0.1875)>mid-uphill(0.1905)>Middle(0.3740)>uphill slope(0.3771).Which shows that the overall performance of different slopes is gradually becoming better,the uphill is the worst and the downhill is the best. |
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