【作者】 柏方敏；

【导师】 田大伦；

【作者基本信息】 中南林业科技大学 ， 生态学， 2010， 博士

【摘要】 洞庭湖是我国第二大淡水湖,为我国九大商品粮基地和十大淡水养殖基地之一。为保障湖区农业的稳定和持续高产,在原有防护林建设的基础上,1998年又启动了以改善生态环境和发展农业为目的的中德合作生态造林项目,项目目标在湖区8个县市区五年内完成封山育林(Preserved forests for soil and water conservation on hilly areas along the lake(PF))、补植封山育林(Replanting preserved forests for soil and water conservation on hilly areas along the lake (RPF))、平原湖区防护林(Protective forest bands on plain area(PFB))、防浪护堤林(Wave-break Forest bands along the shores of the lake(WFB))3万公顷的营造任务。本研究在项目区澧县选择上述4种营造成功的防护林,对这4种防护林的土壤理化性质、植物组成、生物生产力、养分积累、碳储存及生态影响评价进行了研究,主要研究结果为：1、封山育林、补植封山育林和平原湖区防护林地土壤为红壤、pH值4.54-5.27,呈酸性,土壤质地为粘土类；防浪护堤林地土壤为湖潮土,pH值为8.18,呈碱性,土壤质地为壤土类；有机质含量11.03-29.00g·kg-1,且封山育林地显著高于补植封山育林、平原湖区防护林和防浪护堤林地(p<0.05)；土壤中N素有效率低、仅为1.46%；P含量不高,仅0.16-0.67g·kg-1,且防浪护堤林地显著高于其余三种防护林地(p<0.05)；K元素含量在4种防护林地间差异不显著(p>0.05),为2.53-2.90 g·kg-1；Ca、Mg含量以防浪护堤林地最高,分别为16.89 g·kg-1、5.03 g·kg-1,且显著高于其余三种防护林地的27-41倍和3-4倍(p<0.05)；微量元素以Fe含量12555.40-15249.80 mg·kg-1最高,Cd 0.06-0.09 mg·kg-1最低,Mn含量249.80-865.98 mg·kg-1, Zn 65.16-99.28 mg·kg-1, Cu 31.57-44.16 mg·kg-1,Ni 36.59-56.26 mg·kg-1,Pb 22.08-29.99 mg·kg-1,Co 3.79-6.67 mg·kg-1。2、4种防护林物种丰富度指数为：封山育林乔木层9、灌木层17、草本层8,补植封山育林20、24、10,平原湖区防护林6、5、5,防浪护堤林1、2、33；Shannon-Wiener多样性指数为封山育林乔木层0.893、灌木层2.432、草本层0.996,补植封山育林2.051、2.643、1.455,平原湖区防护林0.654、1.187、1.284,防浪护堤林O.000.0.673.3.010;Simpson多样性指数为封山育林乔木层0.393、灌木层0.882、草本层0.456,补植封山育林0.827、0.912、0.701,平原湖区防护林0.326、0.605、0.691,防浪护堤林0.000、0.480、0.947；Pielon均匀度指数为封山育林乔木层0.406、灌木层0.858、草本层0.479,补植封山育林0.685、0.832、0.632,平原湖区防护林0.406、0.737、0.708,防浪护堤林0.000、0.971、0.860。4种防护林林下植被物种数逐步增加,有利于林地保护和地力维持。3、4种防护林中,封山育林22年生马尾松单株生物量为56.83kg,补植封山育林8年生马尾松为4.27kg、8年生湿地松为3.62kg,平原湖区防护林10年生湿地松为20.46kg、6年生马尾松为5.07kg,防浪护堤林10年生杨树林为193.79kg；防护林主林层生物量为封山育林109.97t·hm-2,补植封山育林4.51 t·hm-2,平原湖区防护林28.57 t·hm-2,防浪护堤林116.27 t·hm-2,生产力为封山育林5.00 t·hm-2·a-1,补植封山育林0.58 t·hm-2·a-1,平原湖区防护林3.37 t·hm-2·a-1,防浪护堤林18.97t·hm-2·a-1；防护林下植被层生物量为封山育林3.66 t·hm-2,补植封山育林27.03 t·hm-2,平原湖区防护林5.69t·hm-2,防浪护堤林5.11 t·hm-2;死地被物层生物量封山育林、补植封山育林、平原湖区防护林和防浪护堤林分别为1.40 t.hm-2、2.01 t.hm-2、0.97 t·hm-2和1.73 t·hm-2。各防护林生态系统生物量、生产力较高,结构层次合理,中德合作生态造林结果是成功的。4、4种防护林植物体内大量营养元素含量为：N 4.05-39.04 g.kg-1, P O.33-6.97g.kg-1,K1.08-33.23 g.kg-1,Ca 1.50一21.00 g.kg-1,Mg 0.67-4.86g·kg-1；微量元素植物体内含量在160.00 mg.kg-1以上为Fe元素,在15.00mg.kg-1以下的有Ni、Pb、Cd、Mn、Zn、Cu元素。防护林植被系统中以10年生杨树积累的N、P、Ca、Mg、Cu、Ni、Pb的最高；以22年生马尾松积累的K、Fe、Mn、Zn、Cd最多。发现青冈、山矾、冬青是积累土壤中重金属元素Cd的优良木本植物,生物吸收系数值分别达4666.7、2800.0、1085.7,可作为Cd污染严重土壤修复的优选树种。防护林死地被层养分积累量,封山育林积累的大量元素和微量元素分别为36.23kg.hm-2、1650.18 g.hm-2,补植封山育林为41.22 kg·hm-2、2357.96 g·hm-2,防浪护堤林56.19 kg·hm-2、1936.83 g·hm-2,平原湖区防护林33.62 kg·hm-2、879.65 g·hm-2。前3种防护林更有利于林地养分的维持5、防护林地土壤碳含量为4.14-20.62g·kg-1,碳贮存量为65.57-68.33t·hm-2,且随土层加深而下降；植被系统碳贮量为15862.96-60730.86 kg·hm-2；死地被物层碳贮量为618.74-1286.45kg·hm-2。防护林生态系统碳素总贮量为:封山育林121.49t·hm-2,补植封山育林84.85t·hm-2,平原湖区防护林73.04t·hm-2,防浪护堤林129.87t·hm-2。构成防护林生态系统碳素总贮量三个分室的碳贮量大小排序为土壤层>植被层>死地被物层。6、对4种防护林的直接经济效益价值及水源涵养、固土保肥、固碳放氧、净化大气候、美学景观、防浪和改善当地气候等生态影响价值进行了估算和评价。结果表明,洞庭湖区营造的4种防护林每年产生的生态效益价值为31.02亿元,占总效益96.3%,每年以木材生产为主的直接经济效益为1.18亿元,仅占总效益的3.7%。表明中德合作洞庭湖生态造林结果,达到了预期目的。更多还原

【Abstract】 Dongting Lake is the second largest freshwater lake in China, and Dongting Lake region is one of the most important commodity grain production bases and the significant freshwater aquaculture products bases in the country as well. In order to maintain a sustainable high production in both agriculture and aquaculture in this region, a China-Germany collaboration afforestation project was started up in 1988 based on the initial establishment of protective forests. The objective of the project was to complete a total of 30,000 ha of afforestation area in eight counties in the region by five years with four major protective forest types:Preserved forests for soil and water conservation on hilly areas along the lake (PF), Replanting preserved forests for soil and water conservation on hilly areas along the lake (RPF), Protective forest bands on plain area (PFB), and Wave-break Forest bands along the shores of the lake (WFB). In the present study, physical and chemical properties of soils, vegetation composition, biomass productivity, nutrient element accumulation, and carbon storage were investigated in the four protective forest types in Li County within the Dongting Lake region. The results showed:1. The soils belonged to red soil, and were clay-textured and acidic with pH value of 4.54-5.27 in PF, RPF and PFB, but were lake-tide loam-textured and alkaline with pH value of 8.18 in WFB. Soil organic matter (SOM) ranged from 11.03 to 29.00 g.kg-1 in the study stands, in which SOM was significantly higher in PF than in other three forest types (p <0.05). In the study sites, available nitrogen (N) accounted only for 1.46% of total N in soils and phosphate (P) content level was low with the value of 0.16-0.67 g.kg-1. P content was the highest in WFB, which was significantly higher than those in other three forest types (p< 0.05). No statistic difference was found in terms of (potassium) K content (ranged 2.53-2.90 g.kg-1) among the four forest types (p< 0.05). Calcium (Ca) and Magnesium (Mg) contents in WFB (16.89 and 5.03 g.kg-1, respectively) were as high as 27-41 and 3-4 times of that in other forest types, respectively (p< 0.05). The concentrations of micronutrients in soils in the study sites ranged as:Fe:12555.40-15249.80 mg.kg-1, Cd:0.06-0.09 mg.kg-1, Mn:249.80-865.98 mg.kg-1, Zn:65.16-99.28 mg.kg-1, Cu: 31.57-44.16 mg·kg-1, Ni:36.59-56.26 mg.kg-1, Pb:22.08-29.99 mg·kg-1, and Co:3.79-6.67 mg.kg-1.2. It was found that species richness indexes in tree, shrub, and herbaceous layers in the four protective forest types were:9,17, and 8 in PF; 20,24, and 10 in RPF; 6,5, and 5 in PFB; and 1,2, and 33 in WFB. Shannon-Wiener diversity index was 0.893,2.432,0.996; 2.051,2.643, 1.455; 0.654,1.187,1.284; and 0.000,0.673,3.010 in tree, shrub and herbaceous in PF, RPF, PFB and WFB, respectively. Simpson diversity index in tree, shrub, and herbaceous was 0.393,0.882,0.456; 827,0.912, 0.701; 0.326,0.605,0.691; 0.000,0.480,0.947 in PF, RPF, PFB and WFB. Pielon evenness index were 0.406,0.858,479; 0.685,0.832,0.632; 0.406, 0.737,0.708; 0.000,0.971,0.860 in tree, shrub and herbaceous in PF, RPF, PFB, and WFB, respectively. The number of understory plant species was gradually increased with stand ages in the four forest sites, which would facilitate to soil and water conservation and maintains of soil fertility.3. Among the four protective forest types, average biomass of individual tree was 56.83 kg in 22-year old Masson pine forests in PF; 4.27 kg in 8-year old Masson pine and 3.62 kg in 8-year old Slash pine forests in RPF; 20.46 kg in 10-year old Slash pine and 5.07 kg in 6-year old Masson pine forests in PFB; and 193.79 kg in 10-year old Poplar forests in WFB. On average, biomass in over-storey was 109.97,4.51,28.57 and 116.27 t.hm-2 in PF, RPF, PFB and WFB, respectively. Annual productivity of the forest stands was 5.00,0.58,3.37 and 18.97 t.hm-2.a-1 in PF, RPF, PFB and WFB. Biomass in under-storey was 3.66,27.03,5.69 and 5.11 t.hm-2 in PF, RPF, PFB and WFB. Biomass in litter layer on the floor was 1.40,2.01,0.97 and 1.73 t.hm-2 in PF, RPF, PFB and WFB, respectively. The results indicated that the China-Germany afforestration project was successful with better stand vertical structures and relative high biomass production and site productivity in the four protective forest ecosystems. 4. The concentrations of macronutrient elements within plant organs ranged 4.05-39.04 g.kg-1(N),0.33-6.97g.kg-1(P),1.08-33.23 g.kg-1 (K), 1.50-21.00 g.kg-1 (Ca), and 0.67-4.86 g.kg-1 (Mg) in the four forest types. Besides a relative high concentration of Fe (> 160.00 mg.kg-1) in plant organs, the concentrations of other micronutrient elements (Ni, Pb, Cd, Mn, Zn and Cu) were all less than 15.00 mg.kg-1. It was found that the elements (N, P, C, Mg, Cu, Ni and Pb) were mostly accumulated in 10-year old Poplar forests highest, while the highest accumulation amount of K, Fe, Mn, Zn and Cd was appeared in 22-year old Masson pine forests. It was also found that three tree species(Cyclobalanopsis glauca, Symplocos caudate, and Ilexpurpurea) had the strongest capability to absorb and accumulate heavy metal element, Cd, with the biological absorption coefficient of 4666.7, 2800.0,1085.7, respectively. As a result, the three tree species can be chosen as ideal plant species for remediation and restoration of serious Cd-contaminated soils. The amount of macro-and micronutrients in the litter layer on the floor was 36.23 and 1650.18; 1.22 and 2357.96; 56.19 and 1936.83; and 33.62 kg.hm-2 and 879.65 g.hm-2 in PF, RPF, PFB, and WFB, respectively. It showed that soil fertility was better maintained in PF, RPF and PFB types.5. Concentration of carbon in soils ranged from 4.14 to 20.62g.kg-1 in the studied sites. The carbon storage was from 65.57 to 68.33 t.hm-2 and was declined with soil depth in the four protective forest types. Carbon storage was 15862.96-60730.86 kg.hm-2 in vegetation compartment and 618.74-1286.45 kg.hm-2 in litter layer compartment on the floor. On average, the carbon storage was 121.49,84.85,73.04, and 129.87 t.hm-2 in PF, RPF, PFB and WFB, respectively. The size of carbon pool in the studied forest ecosystems was in order soil> vegetation> litter layer.6. The direct economic benefits of timber production and indirectly benefits of ecological services of the protective forests, such as water resources conservation, preventing soil erosion, carbon sequestration, purification of air, landscape aesthetics, regulating local environment conditions were assessed and calculated. Our results showed that total annual value of the protective forests in the studied region was about 3.22 billion yuan (RMB), of which the ecological benefit was 3.1 billion yuan (RMB), accounting for 96.3% of the total values. The direct economic benefit (timber production) was 0.18 billion yuan (RMB) and accounting for only 3.7% of the total values. The results suggested that the China-Germany afforestration project in Dongting Lake region was successful and yielded a great deal of ecological, economic and social benefits.更多还原