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Study on Water Conservation Function of Ecosystem of Picea Crassifolia Forest in Qilian Mountains

Author: ZhangJianHui
Tutor: CheKeJun；WangHui
School: Gansu Agricultural University
Course: Forest Management
Keywords: Qinghai spruce forest Ecosystem Water Conservation Function Moss litter Soil Water quality Qilian Mountains
CLC: S718.5
Type: Master's thesis
Year: 2010
Downloads: 86
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Abstract

Forest ecosystems with more complex material circulation and energy conversion channel, occupies an important position in the Geosphere - Biosphere biogeochemical cycles. On the basis of long-term position in the Qilian Mountain forest ecosystem research, from the ecosystem point of departure, through the observation of typical watershed in Qilian Mountains spruce forest ecosystem hydrology, climate, soil, Water conservation function of its ecosystem analyzed. The results show that: 1. The small climatic characteristics of the Qilian Mountains in Qinghai spruce forest: forest within the temperature changes in amplitude than the forest outside the small 3.91 ° ??C, the annual average temperature Linneibilin low 0.1 ° C; relative humidity within the forest than the forest outside high eight points; make forest precipitation intensity , precipitation was significantly smaller than outside the forest. 2 test area of ??spruce forest in Qilian Mountains, elevation gradient, the transition zone of a small watershed vegetation types and other vegetation types, precipitation dramatic changes. Show that the region of different vegetation types in certain geographical environment and scale precipitation. 3 Qilian Mountains spruce forest ecosystem to Precipitation: Forest Canopy interception characteristics: in certain rainfall level within the range of the general trend of the interception increases with increasing precipitation, retention rate trends as precipitation decreases; rainfall intensity the greater the smaller the retention rate; same rainfall intensity, the rejection rate increases with canopy density. Qilian Mountains spruce forest ecosystem precipitation allocation process: the canopy layer, moss and litter layer and the soil layer interception of broadly similar, can be divided into three processes: With the increase in precipitation, the first stage for the retention phase interception rejection rate increases with the increase of rainfall input; second stage permeate stage, the interception by the cumulative amount of the first stage increases, but the retention rate gradually decreases; The third stage is the stage of saturation, the interception reach maximum, the retention rate is close to zero. Permafrost as the impervious layer and the storage layer: permafrost inhibit the infiltration of water into deep sand, increasing the depth of runoff. The same time can increase runoff in late spring and early summer, autumn, summer and winter precipitation to fall stranded, improve the water storage capacity of the basin. ? 4. Qilian Mountains spruce understory moss litter the composition and hydrological characteristics: Qilian Mountains Forestry Area spruce forest moss litter average thickness of 8.2cm; undecomposed moss litter component accounted for 42.8% of the total; half decomposition and decomposition component accounted for 23.8% and 33.4%, respectively; litter composition of 67%, leaves, branches accounted for 17%, 16% fruit. ? Moss litter layer maximum water holding rate varied between 276.65% to 370.48%, 322.53%, on average, the Qinghai spruce forest moss litter in the water holding capacity of about three times its own dry weight; The maximum water holding capacity ranged from 7.6 ~ 29.1mm, an average of 18.4 mm. Qilian Mountains spruce understory soil physical properties and hydrological characteristics: Qinghai spruce understory soil physical properties and sloping pasture (control) compared Qinghai spruce forest soil bulk density (0.764g/cm3) is less than the sloping pasture ( 1.231 g/cm3). Soil non-capillary porosity (16.77%) is less than the sloping pasture (10.2%); on the soil surface, the sloping pasture soil bulk density (1.45 g/cm3) Qinghai spruce forest soil bulk density (0.42 g/cm3) 3 times ; with the soil depth, the the Qinghai spruce forest soil bulk density is gradually close sloping pasture. The Qinghai spruce understory Soil water performance and the sloping pasture (control) compared to soil maximum water holding capacity of 131.9% and 27.15%, respectively, with an average minimum water holding capacity of 79.95% and 15.05%, the capillary 105.1% of the amount of water and 20.22%; in soil surface, Qinghai spruce understory soil water holding capacity, the minimum water holding capacity and capillary moisture was significantly higher than the sloping pasture; increase with soil depth, soil water holding capacity, the minimum water holding capacity and capillary held the water close to the sloping pasture soil . Soil penetrate speed: initial infiltration of surface soil speed and steady infiltration speed is greater than the lower soil above the sloping pasture soil. Qinghai spruce understory soil moisture changes with sloping pasture (control) compared to the soil surface, soil moisture variations, and the sloping pasture soil water content higher than that of Qinghai spruce forest. With the increased soil depth, soil moisture changes gradually stable; soil moisture changes in the seasonal variation of: water consumption period (May to June), soil moisture accumulation period (July to August), soil moisture resolution phase (September), soil moisture stabilization period (October). Precipitation after the Qilian Mountains spruce canopy, the concentration of mineral elements through the rain submission have changed, doubling the total ion content. Most of the content of chemical elements in water increases, the largest increase for K through rain concentration is 3.4 times the atmospheric precipitation; each chemical element content of the order: K gt; P GT; Ca GT; Mg gt; Zn gt ; Mn gt; Fe gt; N gt; Cu

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