陇东黄土高原人工刺槐林枯落物层和土壤层生态水文功能研究

发布时间：2018-12-14 22:10

【摘要】：在甘肃泾川县官山林场中沟小流域,以林龄25年以上的人工刺槐林为研究对象,采用林分结构调查法、室内浸泡法、土壤剖面调查法、及土壤水分-物理性质测定等方法,按不同林分密度划分为6个密度(750株/hm2、1227株/hm2、1600株/hm2、2196株/hm2、3780株/hm2、4563株/hm2),研究不同林分密度条件下林地枯落物层与土壤层的生态水文特征,揭示不同密度人工刺槐林枯落物层的持水性特征、土壤物理特性、持水能力及渗透性特征,深入了解人工林植被与土壤及枯落物生态水文功能相互关系,为该地区合理经营人工林利用有限的水资源,科学建设森林植被提供理论参考,主要研究结论如下:(1)6种密度人工刺槐林枯落物的总蓄积量变动范围在8.09~13.40t/hm2之间,随着林分密度的增加,林下枯落物呈现先增大后减小的趋势,林下未分解层蓄积量占总蓄积量的百分比大致呈现逐渐增加的趋势,其变化范围为41.00%~62.83%,而半分解层所占比例逐渐减小,变化范围为37.17%~59.00%。不同林分密度枯落物的未分解层和半分解层的持水过程基本相似,不同密度刺槐人工林枯落物持水速率与浸泡时间的幂函数关系较为显著。各样地枯落物总有效拦蓄量的变动范围为:8.03~33.4 t/hm2,整体表现为随着林分密度的增加,有效拦蓄量呈现先增大后减小的趋势,且未分解层比半分解层有效拦蓄量高。(2)随着林分密度变化,不同林分密度土壤平均容重总体表现为750株/hm21227株/hm21600株/hm22196株/hm24563株/hm23780株/hm2;土壤总孔隙度与非毛管孔隙度均值分别为3.96~12.00%、44.60~53.07%,其变化趋势与容重均值相反。在0-40cm不同林分密度土壤容重、总孔隙度及非毛管孔隙度差异显著(P0.05),40cm以下土层各样地土壤容重、总孔隙度与非毛管孔隙度差异不显著(P0.05)。各样地最大持水量在20~40cm与40~60cm土层差异显著(P0.05),分别表现为3780株/hm24563株/hm22196株/hm21227株/hm2750株/hm21600株/hm2和4563株/hm22196株/hm21227株/hm23780株/hm2750株/hm21600株/hm2。(3)不同密度人工刺槐林各时段内平均渗透速率最高的是密度为4563株/hm2刺槐人工林,密度为750株/hm2刺槐人工林样地最低。各个人工刺槐林样地土壤初渗率由高到低依次排序为4563株/hm23780株/hm22196株/hm21227株/hm2750株/hm21600株/hm2,土壤稳渗速率最高的是密度为4563株/hm2刺槐人工林(3.40 mm/min),密度为750株/hm2刺槐人工林(0.82 mm/min)最低。(4)各人工刺槐林样地土壤水分在生长季前期(即展叶期)较为稳定,且随着林分密度的增大表现为先增大后减小的趋势;进入生长季之后,土壤含水率逐渐表现出亏损,且到生长季后期除密度为1600株/hm2样地,其它几个均表现出一定程度的亏损,密度为4563株/hm2样地甚至出现中度土壤干化现象。(5)综合分析枯落物与土壤层的最大持水量和有效持水量,得出土壤层所占林地总量比例的96%以上,因此土壤层是林地调节降水和滞留水分的主要场所。采用坐标综合评定法对不同林分密度刺槐人工林枯落物层与土壤层生态水文功能综合评价的结果为4563株/hm23780株/hm22196株/hm21600株/hm21227株/hm2750株/hm2,其结果与土壤层的评价结果一致,表明土壤层是林地水文调节功能发挥的主要场所。
[Abstract]:In the small watershed of Guanshan Forest Farm, the Guanshan Forest Farm, Gansu Province, the artificial Robinia pseudoacacia forest with the forest age of over 25 years was used as the research object. The method of forest sub-structure investigation, indoor soaking method, soil profile survey and soil water-physical property determination were used. The ecological and hydrological characteristics of the litter layer and the soil layer under different forest sub-densities were studied according to the different forest sub-densities to 6 densities (750 plants/ hm2, 1227 plants/ hm2, 1600 plants/ hm2, 2196 plants/ hm2, 3780 plants/ hm2 and 4563 plants/ hm2). The physical characteristics of the soil, the water holding capacity and the permeability characteristics, in-depth understanding of the relationship between the vegetation of the plantation and the ecological and hydrological functions of the soil and the litter, provide the theoretical reference for the rational management of the artificial forest in the region, and provide the theoretical reference for the scientific construction of the forest vegetation. The main research conclusions are as follows: (1) The variation range of total accumulation of 6 kinds of density artificial Robinia pseudoacacia forest was in the range of 8.09-13.40t/ hm ~ 2, with the increase of the forest sub-density, the lower litter of the forest was first increased and then decreased, and the accumulated volume of the undecomposed layer in the forest accounted for a gradual increase in the percentage of total accumulated volume. The range of variation is 40.00% ~ 62.83%, while the proportion of semi-decomposed layer is gradually reduced, and the range of variation is 37. 17% ~ 59. 00%. The water-holding process of the undecomposed layer and the semi-decomposition layer of different forest sub-density litter is similar to that of the semi-decomposition layer, and the relationship between the water-holding rate and the power function of the soaking time is significant. The variation range of total effective retention of all dry and dry land is: 8.03 ~ 3.4t/ hm ~ 2, and the overall performance is that with the increase of the forest sub-density, the effective impoundment shows the tendency to decrease, and the undecomposed layer is more effective than the semi-decomposition layer. (2) With the change of the density of the forest, the average bulk density of the different forest sub-densities was 750/ hm21227/ hm21600/ hm24563/ hm23780/ hm ~ 2; the mean and non-gross porosity of the soil were 3.96-12.00%, 44. 60-53. 07%, respectively. The bulk density, total porosity and porosity of non-gross tube of different forest in 0-40cm were significant (P0.05), and the total soil bulk density, total porosity and non-gross tube porosity were not significant (P0.05). The maximum water holding capacity in all areas was between 20-40cm and 40-60cm (P0.05). It showed that it was 3780/ hm24563/ hm22196/ hm21227/ hm2750/ hm21600/ hm ~ 2 and 4563/ hm22196/ hm21227/ hm23780/ hm2750/ hm21600/ hm2. (3) The average penetration rate of Robinia pseudoacacia plantation with different density was 4563/ hm ~ 2 of Robinia pseudoacacia plantation, and the density was 750/ hm ~ 2 of Robinia pseudoacacia plantation. The soil initial infiltration rate of each artificial Robinia pseudoacacia stands from high to low in order of 4563/ hm23780/ hm22196/ hm21227/ hm2750/ hm21600/ hm2, with the highest soil stabilization rate of 4563/ hm2 of Robinia pseudoacacia (3.40 mm/ min) and the lowest density of 750/ hm2 of Robinia pseudoacacia (0.82 mm/ min). (4) The soil moisture of each artificial Robinia pseudoacacia is more stable in the early stage of growth season (that is, the leaf period), and with the increase of the forest sub-density, the trend of decreasing is first increased; after the growth season, the water content of the soil gradually shows a loss, In addition, at the later stage of the growth season, the density was 1600 plants/ hm2, and the other several showed a certain degree of loss, and the density was 4563 plants/ hm2, and even moderate soil drying was observed. (5) The maximum water holding capacity and the effective water holding capacity of the dry and soil layer and the soil layer are comprehensively analyzed, and the soil layer accounts for more than 96% of the total amount of the forest land, so the soil layer is the main place for regulating the precipitation and the retention of water in the forest land. The results of the comprehensive evaluation on the ecological and hydrological function of the litter layer and the soil layer in different forest sub-density of Robinia pseudoacacia were 4563/ hm23780/ hm22196/ hm21600/ hm21227/ hm2750/ hm2, and the results were consistent with the results of the evaluation of the soil layer. It is indicated that the soil layer is the main place to play in the function of the hydrological regulation of the forest land.
【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714

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