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缙云山典型林分对径流水质的作用及评价研究

Effects of Typical Forest Stands on Water Qulity of Runoff and Its Evaluation in Jinyun Mountain, Southwestern China

【作者】 刘楠

【导师】 王玉杰;

【作者基本信息】 北京林业大学 , 水土保持与荒漠化防治, 2011, 博士

【摘要】 本论文结合“十一五”国家科技支撑项目“重庆北部水源区水源涵养林构建技术试验示范(2006BAD03A1802)”,研究了重庆缙云山典型林分对径流及水质的影响,以期为重庆水源涵养林建设提供科学依据。研究样地计8个:马尾松×四川大头茶混交林(I1)、四川大头茶×四川山矾混交林(I2)、毛竹林(I3)、灌丛(I4)、马尾松×广东山胡椒混交林(I6)、广东山胡椒×杉木混交林(I7)、及毛竹×四川山矾×马尾松混交林(I8)等典型林分为研究对象,同时以裸地(I5)作为对照。首先,统计分析2002-2009年的降雨和径流监测数据,得出了该地区的降雨和产流特征。第二,首次在该地区森林水质研究中引入空气质量监测和云雾水水质的监测,了解空气质量和云雾与降雨化学性质的关系;在2007-2010年期间,对实验地区降雨、林内雨、地表径流和壤中流的水质进行监测与分析,通过对降雨、林内雨、地表径流和壤中流的分析,揭示典型林分不同层次(林冠层、枯落物层、土壤层)的水质效应及影响水质变化的原因;首次对该地区枯落物对酸雨的响应进行人工模拟试验研究,探讨典型林分枯落物对酸雨水质的影响。第三,研究了酸雨影响下森林优势乔木叶片、枯落物、土壤养分储量以及其碳储量的特征,并以这三个对象为三个层次,研究了三个层次间元素含量的相关性,探索它们之间的相互影响关系。对酸雨影响下的典型林分土壤、枯落物养分储量和酸缓冲潜力进行综合评价。第四,使用单因子评价、综合指数法、主成分分析与聚类、灰色关联法和BP神经网络法对典型林分地表径流和壤中流的水质状况进行综合评价。结果如下:(1)缙云山2002年-2009年平均年降雨量为1233.2mmm,主要集中在4-10月份,暴雨多发生在6-9月,且降雨量大,降雨强度高。缙云山典型林分径流量以5-8月最多,地表径流量占全年的51.05%-65.90%,地下径流量占55%-68.4%。有林地对降雨、径流的调节作用要优于裸地,林地中毛竹林(I3)调节径流的能力最差,马尾松×四川大头茶混交林(I1)和四川大头茶×四川山矾混交林(I2)较优。(2)缙云山地区主要空气污染气体为SO2。云雾水pH平均值(3.45)小于同期降雨pH平均值(4.04)且所含的离子浓度高于雨水。该地区降雨酸化严重,有向复合型酸雨转化的趋势。(3)对典型林分不同层次水质效应的分析表明:①降雨呈酸性,林冠层使降雨pH值降低,地表径流和壤中流的pH比降雨有明显的升高,其中地表汇流阶段对水体pH的缓冲作用最大。降雨中所含离子的浓度在其经过林冠层之后,除了Na+以外,其全部呈现增加的趋势。②除Ca2+外,典型林分对降雨输入的离子均有不同程度的削减作用,对SO42-、NH4+、Mg2+、Mn和A13+的削减主要阶段是地表汇流阶段,对N03"、K+、Na+和Fe的截留则主要是土壤层。③地表径流元素浓度与枯落物或者土壤中该元素的储量关系不大;壤中流相应元素的浓度与土壤中该元素的储量具有一定的关系,除了Mg2+和Mn(仅在I2、I4壤中流检出)外,其余元素在壤中流的浓度与其在土壤中的储量均具有正相关或者负相关的关系。(4)枯落物酸缓冲潜力综合评价结果为:P3(-82.01)>P7(-93.85)>P8(-94.98)>P6(-95.90)>P1(-97.58)>P4(-100.08)>P2(-103.16), I3枯落物的缓冲潜力最大,I2最小。土壤酸缓冲潜力综合评价结果为P6(29.37)>P4(23.23)>P8(22.71)>P7(18.50)>P1(15.39)>P2(13.61)>P3(13.22)>P5(11.31),林地土壤缓冲能力优于裸地,I6的缓冲能力最大,I1最小。(5)对I1、I2、I3、I4、I6、I8等6种典型林分枯落物进行的模拟酸雨淋溶实验的结果表明:6种枯落物对模拟酸雨pH值有一定的缓冲能力,在pH值2.7、3.5和4.5酸雨作用下,林分I8的枯落物层对pH值的缓冲效果最好。随着模拟酸雨pH值的降低,6种典型林分枯落物淋滤液中的盐基离子(Ca2+、Mg2+、K\Na+、H4+)、Al3+、Fe、Mn浓度呈现增加的趋势。林分I8的淋滤液中Ca/A1的摩尔比始终处于较低水平,较容易受到铝毒危害。当酸雨pH值降低到2.7时,在几种林分中,林分I8的Fe(4.4μmol/L)、Mn(10.7μmol/L)的含量均为最高的,表明该林分较易受到重金属的危害。(6)对地表径流和壤中流水质综合评价表明:该地区马尾松×四川大头茶混交林具有较好的水质效应。

【Abstract】 The research about effects of subtropical typical forests on runoff and water qulity in Jinyun Mountain was conducted, which are associated with the national 11th five-year key project of state forestry administration "Technology Research and Demonstration of Vegetation Construction with Water Conservation Function in Water district of northern Chongqing city" (2006BAD03A1802). The purpose of this paper is to provide evidence for water conservation forest construction in Chongqing city, southwest China.Based on analysis of forest communities of Jinyun Mountain,8 plots were set:Pinus massoniana×Gordonia acuminate mixed forest(I1), Gordonia acuminate×Symplocos setchuensis mixed forest(I2), Phyllostachys pubescens forest(I3), shrub forest(I4), Lindera kwangtungensis×Cunninghamia lanceolata mixed forest(I6), Phyllostachys pubescens×Symplocos setchuensis×Pinus massoniana mixed forest(I7), Pinus massoniana×Lindera kwangtungensis mixed forest(I8) and bareland(I5).In this study, firstly, the characteristics of rainfall and runoff yield were discovered by analyzing the precipitation and runoff monitoring data in 2002-2009. Secondly, air quality monitoring and cloud-fog water qulity monitoring were introduced into study to reaserch relationship between their qulity and rainwater qulity. During 2007-2009, according to the temporal and special orders of interaction between water and forest ecosystem, the ecosystem was divided into several layers and every layer water quality along rainfall-runoff process was studied by comparing, contrasting and mechanism analyzing. The rainwater, through fall water, surface runoff and inter flow were collected and chemically tested. The hydro-chemical properties of litter layers of typical forests were also studied by the simulated acid rain experiment. Thirdly, the nutrient and carbon storage of dominant trees leaves, litters and soil. The element content correlation among leaves litters and soil was studied. And the acid buffer potentiality of soil and litters in typical forests was comprehensive evaluated. Finally, the water qaulity of surface runoff and interflow was assessed by single-factor evaluation, comprehensive index method, principal component analysis and cluster analysis, grey correlation analysis and BP neural network method. The mainly results in the study were as follows:(1)During 2002-2009, the average precipitation in Jinyun Mountain was 1233.2mm, and mainly rained from April to October. Rain storm mainly occurred in June-September, and the precipitation and rainfall intensity were great. Runoff yields in plots were largest in May-August. In this period, surface runoff took 51.05%-65.90% of annual quantity, and interflow took 55%-68.4%. Regulatory effects of forest stands were better than bareland. And I3 had worst ability of regulatory; I1 and I2 had better abilities on this effect. (2)The dominant gaseous pollutant was SO2. Average pH of cloud-fog water (3.45) was smaller than rainwater (4.04) collected at the same time, but its ion content was larger. Acidification of rainfall in the region was serious. The acidrain in this area had a trend to transfer into combined pollution type.(3)The effects of different components of typical forests on water quality during the rainfall to runoff process were investigated. The results showed that:①Rainfall was acidic. The pH of the water increased as it moved through all components of four typical forests except canopy. All elements from rainfall were increased after moving through canopy except Na+.②All elements from rainfall were reduced except Ca2+. The curtailment of SO42-, NH4+, Mg2+, Mn and Al3+ was mainly occurred in runoff generation and confluence period. Soil under typical forest played vital role in the reduction of NO3-, K+, Na+ and Fe.③Surface runoff element contents had little correlationship with litter and soil element contents. But interflow ion content had correlationship with soil element contents. Almost every element in interflow had correlationship with soil element content except Mg2+ and Mn.(4)Result of acid buffer ability evaluation of litter was:P3(-82.01)>P7(-93.85)>P8(-94.98) >P6(-95.90)>P,(-97.58)>P4(-100.08)>P2(-103.16). Litter in I3 had the best acid buffer ability, I2 was the worst. Result of acid buffer ability evaluation of soil was:P6(29.37)>P4(23.23)>P8(22.71) >P7(18.50)>P1(15.39)>P2(13.61)>P3(13.22)>P5(11.31). Acid buffer ability of forest soil was better than bareland.16 was the best among forest stands, and I1 was the worst.(5)The the hydro-chemical properties of litter layers in I1, I2, I3, I4, I6 and I8 were studied by the simulated acid rain experiment. The results showed:The acid buffer ability of litter layer in I8 was best under the leaching of acid rain whose pH=4.5,3.5 or 2.7. Base cation(Ca2+、Mg2+、K+、Na+、NH4+), Al3+, Fe and Mn concentrations of all 6 typical forest litter leachings increased with the decrease of pH of simulated acid rain. The fact that Ca/Al molar ratio of I8 is always at a low level indicated that I8 was more susceptible to aluminum toxicity hazards. Under the eluviation of pH2.7 simulated acid rain, the concentrations of Fe (4.4μmol/L) and Mn (10.7μmmol/L) in I8 litter leaching were larger than that of the others. It indicated that I8 was more vulnerable to these toxic elements.(6)I1(Pinus massonianaX Gordonia acuminate mixed forest) had better water quality situation by water quality evaluation analysis.

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