【作者】 李效雄；

【导师】 刘贤德； 李毅；

【作者基本信息】 甘肃农业大学 ， 水土保持与荒漠化防治， 2013， 博士

【摘要】 祁连山位于欧亚大陆中心，是我国高大山系之一，环境独特、生态系统脆弱，是我国的重点区域和自然保护对象。祁连山水源林在维持整个河西走廊社会-经济-生态复合系统的健康和稳定，以及祁连山各条内陆河径流总量稳定方面起着决定性的作用。在祁连山水源涵养林林分结构中，各种相同或不同的结构彼此关联、相互依从，决定着森林功能的发挥。如果森林结构组成不良或资源量不足，就不能发挥良好的功能，从而严重制约本地区水资源供需，对经济社会发展会产生不利的影响。本文依托国家林业局公益性行业科研专项“典型森林生态系统样带监测与经营技术研究（200904022）”和“西北高寒山地针叶林碳氮水耦合观测、模拟与应用技术（201104009-08）”项目，在祁连山西水林区开展水源涵养林结构与功能研究，进一步拓展和完善水源涵养林结构和生态功能关系的研究技术体系，以期为祁连山水源涵养林建设和生态环境可持续发展提供科学依据。研究内容包括祁连山西水林区青海云杉林群落结构特征、种群结构特征、空间结构特征以及青海云杉林保育土壤功能、涵养水源功能等，主要研究成果如下：青海云杉群落成层现象明显，可划分为乔木层、灌木层、草本层及苔藓层4个层次。乔木层是群落的最主要层次，整体而言其垂直高度结构复杂性要大于灌木层和草本层，苔藓层较为发达；青海云杉种群胸径级频率分布呈“倒J”型，胸径级随个体数的变化符合对数方程y=-219.32ln（x）+482.67（R2=0.9638，P＜0.01），胸径分异指数为0.48，种群个体胸径差异属明显分异；青海云杉DBH≥1cm对应的树高结构多度呈“单峰”形，主要集中在高度级小于4-6m，占到总多度的60.00%，高度偏小，小树较多，中树占有一定的比例，大树较少；青海云杉树高级频率分布呈“间歇”型，不同高度级与个体数之间可用二次方程y=0.975x2-31.23x+285.1（R2=0.603，P＜0.01）进行较好的描述，树高分异指数为0.55，高度差异属明显分异；胸径和树高两者之间符合对数方程y=5.912ln（x）-4.2493（R2=0.603，P＜0.01）；青海云杉冠幅级与个体数之间可用三次方程y=5.3176x3-91.759x2+408.88x-173.87（R2=0.8355，P＜0.01）进行很好的拟合，冠幅分异指数为0.53，种群个体冠幅差异亦属明显分异。总体上看，青海云杉幼苗较为丰富，天然更新能力强，目前表现为成熟稳定型种群。青海云杉直径分布为典型的异龄林直径结构，顶级群落呈单种聚集，空间隔离程度为零度混交，直径大小比数和树高大小比数平均数均为0.49，生长上处于中庸状态，大小分化程度一般，角尺度呈正态分布，其平均值为0.526，从林分水平分布格局上看，青海云杉分布是团状分布，开敞度大小为1.667，生长空间很充足。通过对青海云杉林保育土壤功能研究表明，青海云杉林林地的土壤容重平均值均在0.74g/cm3以上，由表层到底层变异系数在39.02%～14.46%之间。说明植被对上层土壤容重的影响较大；林地土壤总孔隙度、毛管孔隙度和非毛管孔隙度平均值分别为63.86%、49.02%和13.72%，表明祁连山西水林区青海云杉具有较好的透水性；土壤总孔隙度平均值表现为灌木青海云杉林>藓类青海云杉林>草类青海云杉林>青海云杉更新地>无林地；在青海云杉林分布的海拔梯度上，0-40cm土层土壤有机质、全氮及全磷平均含量高海拔高于低海拔，而且高海拔与低海拔差异显著（p<0.05）；土壤全钾和速效钾含量则是高海拔低于低海拔，差异亦显著（p<0.05）；速效磷含量随海拔升高没有明显的变化规律，而且海拔间的差异不显著（p＞0.05）；土壤pH值大小随海拔的升高不断减小，但海拔间的差异不显著（p＞0.05）；在不同土层深度，0-10cm土层土壤有机质、全氮、全磷、速效磷和速效钾平均含量均大于10^-20cm和20-40cm土层含量，而且0-10cm土层含量显著大于20-40cm土层含量（p<0.05）；土壤pH值大小和全钾含量则随土层深度增加，其数值不断增加，pH值在0-10cm土层与20-40cm差异显著（p<0.05），全钾含量在不同土层差异均不显著（p＞0.05）；土壤养分和pH值的相关性分析表明，在碳、氮、磷、钾营养元素循环中，土壤pH值和土壤有机质可能作为首要限制因子来影响青海云杉群落养分供应。青海云杉林林冠截留、茎流和穿透水量分别是139.1、1.97和253.14mm,林冠截留率、茎流率、穿透率分别为35.28％、0.049％和64.21％，当林外降水量大于0.8mm时才观测到林内穿透雨，而大于12.60mm时，才观测到树干茎流；不同森林类型枯落物层现存量，青海云杉林为33.12T/hm2，其中以藓类云杉林最大为45.68T·hm^-2·a-1，云杉林更新地最小为22.04·hm^-2·a-1，灌木云杉林和草类云杉分别为34.19T·hm^-2·a-1和30.57T·hm^-2·a-1。青海云杉林各有林地蓄积量、最大持水率（饱和持水率）和最大持水量以灌木云杉林为最高，分别为34.19t/hm2、149.11%、117.88t/hm2（相当于11.79mm水深）；各有林地均高于无林地。在降水条件下，枯落物层开始截留降雨到吸水饱和的全过程分为截留阶段、渗透阶段和饱和阶段；青海云杉林林地各层饱和持水量均值分布在72.16%～149.11%之间；非毛管持水量均值在10.37%～18.43%之间。土壤非毛管持水量分布规律为藓类云杉林＞灌木云杉林＞草类云杉林＞更新林地＞无林地；有林地土壤入渗速率均高于无林地。无林地的渗透系数K10最小值为0.6mm/min,有林地土壤渗透系数从大到小的顺序灌木云杉林、藓类云杉林、草类云杉林、更新林地、无林地。土壤渗透系数（K10）分别比无林地提高了了54.83倍、44.0倍、32.6倍、11.3倍。无论在旱季还是雨季,有林地各土壤表层、中间层次和底土层各层土壤含水量都明显高于无林地,各土层含水量均值大小表现为:灌木云杉林>青海云杉林>草类云杉林>云杉林更新地>无林地。更多还原

【Abstract】 Qilian Mountains is located in the center of the Eurasian continent, is one of China’s high mountain, unique environment, ecological system is fragile,is China’s key areas and natural protection object.The water conservation forests in Qilian Mountains plays a decisive role in the health and stability of the whole Hexi Corridor social-economic-ecological composite system,and the stability of runoff volume in the inland river and the Qilian Mountains.In the forest stand structure of water conservation forests,all kinds of the same or different structure are interrelated,interdependent,decided the playing of the forest function.If the forest structure is bad or insufficient resources, it can not play a good function, which seriously restricts the supply and demand of water resources in the region,then have an adverse effect on the development of social economy.In this paper, based on the research and public service industry, a special of the State Forestry Administration "Researcher on typical forest ecosystem monitoring and management technology (200904022)"and "Study on the typical forest vegetation formation process regulation of water resources (201104005)"and "Researcher on northwest typical area based on water management on the forest vegetation carrying capacity (200904056)"etc.Research on forest structure and function of water conservation in Xishui forests area of Qilian Mountains to develop and perfect the technical system of the relationship between water conservation forest structure and ecological function,in order to provide scientific basis for the conservation of Qilian mountain forest construction and ecological environment sustainable development.The research is include the community structure, population structure, spatial structure in Xishui forests area of Qilian Mountains and soil conservation and water conservation function of Picea crassifolia,the main research results are as follows:The layer structure difference is obvious for the P. crassifolia community,and it can be divided into tree layer,shrub layer,herb layer and bryophyta layer.The tree layer is the main layer of the community,and its vertical structure is more complex than the shrub layer and herb layer,and the bryophyta layer is also well developed.DBH size class frequency distribution of Picea crassifolia population is "pour J" type,DBH size classweth the change of individual level is quite fit for the logarithmic equation y=219.32In(x)+482.67(R2=0.9638, P<0.01),differentiation index of DBH is0.48,the differences of DBH in the population for each individual is obvious;The height structure of the P. crassifolia indiciduals with DBH greater than lcm is single-peak form,and the height of the main individuals is less than6m,which account for more than60.00%of the total individuals.So the height of the P. Crassifolia individuals is relatively low,and young trees are much,nid terrs hold a certain proportion,and big trees are little.Frequency distribution of the tree height is "intermittent" type,Tree height size class and individual level can be explained by quadratic equation y=0.975x2-31.23x+285.1(R2=0.603, P<0.01),differentiation index of tree height is0.55,tree height difference is evident;The logarithmic equation y=5.912In(x)4.2493(R2=0.603, P<0.01) can be used to show the relation between tree height and DBH;Crown breadth size class and individual are accorded with equation y=5.3176x3-91.759x2+408.88x-173.87(R2=0.8355, P0.01),differentiation index of crown breadth is0.53,the differentiation crown breadth of population individual is apparent. In general,Picea crassifolia seedlings is relatively rich,natural regeneration ability is strong,at present the performance of Picea crassifolia population is the mature stable populations.The diameter distribution of Picea crassifolia stands indicated that it is typical uneven aged diameter structure;Picea crassifolia was climax community and single gathered stands, space isolation degree is zero nitrogen fixation;Mean value of diameter neighborhood comparison and height neighborhood comparison of Picea crassifolia were0.49, its growth was in moderation state, and size differentiation degree was general;Uniform angle index of Picea crassifolia was normal distribution and average of it is0.526, and distribution of Picea crassifolia is round state from the stand level distribution pattern;Open degree of Picea crassifoliawas1.667, for the growth space was very sufficient.The study on the soil conservation function of Picea crassifolia show that:The mean values of soil bulk density were above0.74g/cm3,the coefficient of variation in39.02%～14.46%from the surface layer to the bottom layer.The vegetation have a big influence on soil bulk density of the surface layer.The average values of soil total porosity, capillary porosity and non-capillary porosity were63.86%,49.02%and13.72%,identify that the Picea crassifolia in Xishui forests areas has good water permeability;The sequence of soil total porosity is:Shrub-Picea crassifolia> moss-Picea crassifolia> grass-Picea crassifolia> renewal forests of Picea crassifolia> bare land;In the elevation gradient, soil organic matter, total nitrogen and total phosphorus average content of the0-40cm soil layer at higher elevations higher than low altitude, average content at high altitude and low altitude significant difference (P<0.05); Soil total potassium and rapidly-available potassium content at high altitude is lower than low altitude, difference also significantly (P<0.05); Available phosphorus with the elevations rise without a significant change laws, and the differences between the elevation are not significant (P>0.05); Soil PH value with the elevations rise continuously the size is reduced, but the differences between the elevation are also not significant (P>0.05).(2) In different soil depth, soil organic matter, total nitrogen, total phosphorus, available phosphorus and rapidly-available potassium content at0-10cm soil layer are more than10-20cm and20-40cm soil layer content, and0-10cm soil significant higher than content20-40cm soil layer content (P0.05); Soil PH value size and total potassium content is increased with soil depth, and its numerical is on the increase, PH value in0-10cm soil layer and20-40cm significant difference (P<0.05), but total potassium content in different soil layer are not significant difference (P>0.05).Different soil nutrient and PH value correlation analysis showed that:In the cycling of carbon, nitrogen, phosphorus, potassium nutrient, soil pH value and soil organic matter may as the primary limiting factor to influence the nutrient supply of Pice a crassifolia.The canopy inter ception,stem-flow, thro ughfall are139.1mm,1.96mm and237.8mm,which account for35.28%,0.49%and60.33%,respectively.When precipitation over0.8mm and12.6mm,throughfall and stem-flow could be recorded respectively.The biomass of litter layer in different forest types show that:Picea crassifolia is33.12T/hm2, which moss-Picea crassifolia for a maximum of45.68T·hm-2·a-1,renewal forests of Picea crassifolia for a minimum of22.04hm-2·a-1,Shrub-Picea crassifolia and gxass-Picea crassifolia was34.19T·hm-2·a-1and30.57T·hm-2·a-1,respectively.In the forest land of Picea crassifolia, volume, maximum water holding capacity (saturation water holding rate) and the maximum water holding capacity of shrub-spruce forest was the highest, are34.19t/hm2,49.52%t/hm2,119.50t/hm2(equivalent to11.95mm depth) respectively; the forest land was higher than that of bare land.Under the conditions of precipitation, the interception of litter layer is divided into saturated with water interception, infiltration stage stage and saturation stage;The mean value of saturated water content distribution is65.67%～149.12%in each layer of Picea crassifolia,The mean value of non capillary water capacity is10.64%～18.43%.The sequence of soil non-capillary water-holding capacity is:moss-Picea crassifolia> shrub-Picea crassifolia> grass-Picea crassifolia renewal forests of Picea crassifolia> bare land;The soil permeability rate in forest region is significantly higher than that in non-stocked land. The minimum value permeability coefficient (K10) of bare land is0.68mm/min,The order of soil permeability coeficient in the forests (K10)is shrub-Picea crassifolia> moss-Picea crassifolia> grass-Picea crassifolia> renewal forests of Picea crassifolia> bare land,The permeability coefficient (K10) higher than bare land (38.85times,33.07times,7.29times,4.79times,1.85times, respectively).Both in the dry season or rainy season,The soil moisture content of forest land were significantly higher than bare land, The sequence of mean soil moisture content are as follows:shrub-Picea crassifolia> moss-Picea crassifolia> grass-Picea crassifolia> renewal forests of Picea crassifolia> bare land..更多还原