长白山暗叶林苔藓植物生态功能的研究

本文以长白山暗针叶林中苔藓植物为研究对象，通过野外调查和实验分析，对苔醉植物在暗针叶林生态系统中的生态功能进行了系统地研究。研究内容包括长白山暗针叶林苔藓植物的生物量、对降雨的截留能力、在养分循环中的作用以及苔醉植物浸提液对乔木种子萌发的影响四个方面。研究结论将加强人们对苔藓植物的认识，促进对苔藓植物资源的保护，为进一步研究森林生态系统的生态服务功能和长白山自然保护区的生态价值提供科学依据。主要结论：1）长白山暗针叶林苔藓植物的生物量除海拔1100m夕卜都在2×103kg·hm~(-2)以上。苔醉植物分布并不均匀，随海拔变化生物量差异很大。塔藓和拟垂枝藓的生物量随海拔的变化趋势与暗针叶林优势种臭冷杉和鱼鳞云杉的重要值变化规律相似。2）苔藓一枯落物的成层结构能够大大提高持水能力。苔一枯落物层在一次降雨过程中截留量为4.46mm。通常在降雨发生时苔鲜一枯落物层便开始大量吸水，苔藓-枯落物层含水量逐渐达到饱和，降雨继续增加，持水量出现下降的现象。这种现象随降雨的发生而往复出现。3）随倒木腐烂程度的加深，上面着生的苔醉植物不断发生着演替变化，演替序列被给出。采用C/N随腐烂程度的变化规律对倒木腐烂程度分级进行检验和修正，排序结果更加准确4）苔藓植物体内磷含量较高，是重要的磷库，对维持整个系统的磷平衡有非常重要的作用。不同苔藓盖度的土壤中养分含量有差异，尤其磷差异显著。5）苔藓植物浸提液处理条件下，对红松和鱼鳞云杉的种子发芽有促进作用。

长白山阔叶红松林林地土壤CO2排放规律与机理

土壤CO2释放通量总量与潜力作为陆地土壤碳循环过程研究的重要组分，一直是国际统碳循环研究的前沿领域。鉴于温带森林对全球气候变化的敏感性，以阔叶红松林为代表的土壤CO2 放通量过程与机制的研究，能够为正确评估我国温带森林土壤碳库动态和潜力提供科学依据。本文利用静态箱／气相色谱技术，连续测定了长白山阔叶红松林及其附近的次生林土壤CO2释放通量并进行比较研究，结果表明：（1）长白山阔叶红松林土壤CO2释放通量具有明显的季节动态，与温度的变化趋势大致相同，在生长季节中表现出8月份＞7月份＞9月份＞5月份＞4月份。（2）土壤温度是控制CO2释放的关键驱动因子；土壤含水量变化对CO2 释放亦有一定的影响。（3）不同土壤类型的土壤COZ释放通量强度不同，其中阔叶红松林年C排放量为7253.72 kg/hm2，白桦林排放量为6581.28 kg／hm2，山杨白桦混交林和山杨林排放量分别是6301.64 kg／hm2和4941.77 kg/hm2。（4）凋落物对林地CO2释放有显著的影响，贡献率约占-12％-38％；根系的贡献约为7.26％-57.6％。

基于GIS的长白山森林资源动态与经营分析-以白河林业局为例

本文结合野外调查和森林经营资料，以GIS为核心技术，综合空间分析与多种统计方法，研究了采伐干扰下白河林业局森林资源的动态变化，并使用FoREsTA严森林资源经营管理决策支持系统进行模拟，对多种采伐方案进行了系统的研究。该研究对指导整个长白山区的采伐经营，保护森林资源，实现森林生态系统科学经营与景观管理具有重要的理论意义。主要结论如下：①采伐活动在一定时间内改变植物种群的生态位，伐后10年7个树种的生态位宽度升高并逐渐高出原始林的生态位宽度。其生态位重叠从采伐后至伐后5年降低，以后逐渐升高，20年时与原始林基本相同；伐后灌木种群的生态位宽度与生态位重叠都增大，伐后巧年逐渐降低，伐后20年与原始林基本相同。②采伐强度影响植物群落的多样性，10％采伐强度采伐干扰的乔木的多样性伐后先降低再逐渐增加，20％和30％采伐强度采伐干扰的乔木的多样性随时间变化没有明显的规律；10％与20％采伐强度的灌木的多样性伐后先升高再降低，30％采伐强度的灌木多样性伐后先减少再增加；在所有采伐干扰中，草本层的多样性自伐后5年起逐渐升高，伐后20年，多样性基本趋于稳定。与原始林的多样性相比，10％的采伐强度可以增加乔木、灌木和草本的多样性，20％采伐强度增加了灌木的多样性。③经过13年经营，白河林业局森林林龄、单位蓄积和郁闭度较高等级的森林面积减少，较低等级的森林面积增加。林分质量下降。④经过13年，林业用地景观更加破碎，复杂程度降低，人类的干扰程度增强；基于景观划分的经营类型出现较大差异。⑤利用FoREsTA严决策支持系统进行采伐决策时，应该根据资源分布选择不同的采伐方案。从景观经营的角度，森林景观空间结构方案以及森林景观空间结构方案与实际木材采伐方案相组合后的方案更具有参考价值。

沈阳城市森林生态系统健康与管理研究

本文系统研究了沈阳城市森林的布局与结构、城市森林功能、城市森林病虫害发生与树木健康状况和城市自然资源与社会经济状况等指标对沈阳城市森林生态系统健康与管理的影响。同时一，采用2种生态系统健康评价方法对沈阳城市森林生态系统健康状况进行了评价，并提出了沈阳城市森林生态系统健康管理的对策。研究结果如下：1、截至2004年末，沈阳城市森林植被覆盖率已经达到35％，城市森林林地分布基本合理，但需要进一步加强道路林地、居住区林地和城郊大面积生态林建设。2、沈阳城市森林以乔木为主，乔灌株数比为1.7：1，乔灌的覆盖度比约为7:1。3、沈阳城市森林不同类型林地中植物组成不同。公园林地中有74个属，137个种（变种）；庭院林地中有53个属，104个种（变种）；居住区林地中有45个属，81个种（变种）；道路林地中有43个属，94个种（变种）；运河风景林地中有75个属，142个种（变种）；棋盘山风景林地中有48个属，118个种（变种）。4、公园林地、庭院林地、居住区林地、道路林地和运河风景林地的Shannon一Wiener多样性指数分别为2.78、3.05、3.15、3.18和3.18，均匀度指数分别为0.56、0.66、0.72、0.70和0.64。除了棋盘山风景林地外，沈阳城市森林中栽植总量超过乔木总量5％的乔木树种有7个属，分别为李、柳树、杨树、桧柏、榆树、槐树和银杏，7种树木总量达到了全部乔木总量的82.09％；栽植总量超过灌木总量5％的灌木树种也有7个属，分别为水腊、丁香、李属，小聚、玫瑰、忍冬和连翘，7个属灌木总量达到了全部灌木总量的87.92％。5、公园林地、庭院林地、道路林地和防护林地中OBH＜20cm、20cm＜DBH＜60cm和DBH＞60cm树木的比例分别为：57.9％、40.0％、2.1％，49.2％、47.8％、3.0％，65.3％、33.1％、1.6％和64.6％、34.9％、0.5％，表明沈阳城市森林树木的规格总体上偏小。6、经样方调查和CITYgreen模型计算，沈阳城市森林的生态效益约2.0亿USD／yr.。公园林地、庭院林地和风景林地的景观指标相对较高；道路林地和居住区林地的景观效果一般；防护林地的景观效果较差。7、目前已经发现的沈阳城市森林病害约600余种，虫害约700余种，其中杨树主要病虫害39种，柳树的主要病虫害有33种，榆树和槐树的主要病虫害均为，1种。杨柳树腐烂病、光肩星天牛、天幕毛虫、桃红颈天牛和美国白蛾等是近10年来沈阳城市森林中普遍发生和造成严重危害的主要病虫害。沈阳城市森林主要树木的平均健康指数为2.68，处于一般健康状态。8、沈阳城市森林的土壤和水资源状况均不利于树木的健康生长，沈阳的社会经济发展也有待于进一步提高。9、经过生物指示物法（光肩星天牛为生物指示物）、专家权重法、公众问卷调查和对比研究，沈阳城市森林生态系统总体上处于亚健康状态。10、通过对沈阳城市森林资源、管理状况的调查研究和健康状况的评价，本文提出了沈阳城市森林生态系统健康管理的对策，包括合理规划沈阳城市森林林地布局，增加道路林地、居住区林地和城郊林地的面积和植被覆盖率；调整树木种类组成，避免单一或少数树种的大量栽植，提高生物多样性水平；保护大树和古树；增加城市森林管理资金的投入；应用先进技术，采取科学的病虫害防治和植物养护方法，促进树木的健康生长等。This project systematically studied the urban forest ecosystem health and management in Shenyang. The study explored factors, such as urban forest structure, distribution, pests, aesthetic value, ecological benefit, natural resources and socieo-economic status, that affecting the urban forest ecosystem health and management. Two methods were used to evaluate the ecosystem health. This project also proposed Shenyang's urban forest ecosystem health management strategies. The research results can be summarized as follows: 1. As of the end of 2004, urban forest coverage in Shenyang is about 35%, and is in relatively even patch distribution pattern. However, the street trees and roadside forest patches, residential block forest patches should be enhanced. 2. Trees are the major component of the Shenyang s urban forest, followed by shrubs. The quantity ratio of tree to shrub is about 1.7:1, and the coverage ratio of trees to shrub is about 7:1. 3. Species composition varies by location. There are 74 genera, 137 species (including varieties) in the public parks; 53 genera, 104 species (and var.) in the green spaces of the institution (including school), factory, and company; 45 genera, 81 species (var.) in residential blocks; 43 genera, 94 species (var.) in streets and roadside forest patches; 75 genera, 142 species (var.) in the Canal landscape forest patches; 48 genera, 118 species (var.) in the Qipan Mountain recreation forest. 4. The Shannon-Woener indices varies in parks, in institution, factory, and company yards, in streets and roadside forest patches, in residential blocks.there are 2.78, 3.05, 3.18, 3.15, 3.18, respectively; and the evenness indices are 0.56, 0.66, 0.70, 0.72, 0.64, respectively. Besides the Qipan Mountain forest patches, trees of 7 genera, Prunus spp., Salix spp., Populus spp., Sabina spp., Ulmus spp., Robinia spp. and Ginkgo biloba are of more than 5% the total urban trees, respectively. In fact, trees from these 7 genera are about 82% of all trees in Shenyang's urban forests. In terms of shrubs, species of 7 genera, Ligustrum spp., Syringa spp., Prunus spp., Berberis spp., Rosa spp., Lonicera spp., and Forsythia spp. are more than 5% the total urban shrubs, respectively. 88% of all the shrubs in Shenyang s urban forest are from these 7 genera. 5. The diameter class of DBH<20cm, 20cm60cm of trees in parks, in institution, factory, and company yards, in in streets and roadside forests, and in protective forests are 57.9%, 40.0%, 2.1%; 49.2%, 47.8%, 3.0%; 65.3%, 33.1%, 1.6%; and 64.6%, 34.9%, 0.5%, respectively. The result indicated that the DBH is relatively small in Shenyang s urban forests. 6. Using random plots sampling and CITYgreen model calculation, the ecological benefit of Shenyang's urban is about 0.2 billion US dollars per year. The aesthetic value of parks, institution and company yards, and scenary forest patches is relative high; however, the aesthetic value of protective forest patches is low. 7. There are more than 600 types of diseases and more than 700 kinds of insects in Shenyang's urban forest. Among them, Populus spp., Salix spp., Ulmus spp. and Robinia spp., are attached mainly by 39, 33, 11, and 11, difference types of pests respectively. The rot disease of the Populus spp. and Salix spp., and the insects such as, Anoplophora glabripennis, Malacosoma neustria, Aromia bungii, and Hyphantria cunea are major pests in Shenyang s urban forest for the past 10 years. The trees health condition is relatively poor by having the average health index of 2.68 for major species. 8. The urban soil and water resource are not favorable to tree's growth in Shenyang, and so is the socieo-economic status. 9. Through using bio-indicator, professional and public evaluation, and comparision with other urban forests, it can be concluded that the status of Shenyang s urban forest is not very healthy in general. 10. To improve the urban forest ecosystem health in Shenyang, a better urban forest design need to be implemented to enhance the area and vegetation coverage of the street and roadside forests, the residential block forests, and the surburb forest Species biodiversity need to be enhanced by adjust the species composition of urban forest trees to reduce the single or several tree species populations and to plant more varieties. A better fundings for urban forest health management need to be budgeted. Advanced technologies in tree care and scientific measures to control pests need to be adopted to prove better care for plants and to keep trees grow healthfully.

森林生态系统服务功能评估及效益补偿分析-以长白山白河林业局为例

森林生态服务功能的评价及在人类采伐活动及对其影响的研究，是生态服务功能研究的重点内容，也是当前研究的重点方向。本文以白河林业局为研究区域，选择三个林场为典型代表，利用已有的模型，充分利用森林二类调查数据并结合FORESTAR决策支持系统，综合运用GIS技术和统计方法，研究了森林生态服务功能的时空变化，并通过采伐模拟决策，预测不同采伐方案对其服务功能的影响，旨在揭示采伐与森林生态服务功能间的关系；同时将经济补偿作为解决森林生态效益外部性问题的手段，建立了经济补偿的概念模型，较深入的探讨了补偿标准问题，得出以下主要结论：①森林的涵养水源、固土保肥、吸收二氧化碳、净化空气和抑制风沙的效益中，水源涵养功能单位价值量在各项效益价值量中贡献最大，在森林生态服务功能中占有极其重要的地位。②黄松蒲林场1987年和2000年森林服务功能变化主要是由于郁闭度和林龄的改变，森林资源空间分布的变化导致了生态服务功能的经济价值在20年间减少了近40％。③运用FORESTAR森林决策支持系统模拟不同采伐方案，采伐小班的各项单位效益值都有明显的下降；三个林场经过模拟采伐后总的经济价值分别减少了353.83元／hm~2、448.62元／hm~2和457.13元／hm~2。④将补偿标准用补偿系数和森林服务的价值量来表示，充分反映了在一定社会生产条件下人民生活水平下对森林这种公共产品的支付意愿和森林本身的性质，计算出的补偿系数为0.412，三个林场的补偿费年均分别为1067元/hm~2，1161元/hm~2和1314元/hm~2，同时对其与机会成本比较是单位面积机会成本的近3倍。⑤在补偿政策的实施中，建议建立和健全多层次的经济补偿制度，通过国家财政拨款、跨区域补偿以及当地税收调节等多种途径取得补偿资金，形成跨区域补偿以及在税收中加入生态税这一个项目，可以保证补偿资金来源。

涡动相关法估算森林生产力及与测树学方法的比较

大气中CO2、CH4和其它温室气体浓度升高导致的全球气候变化引起了人们对全球碳循环和碳收支的关注，植被与大气间CO2通量的长期测定能够加深对陆地生态系统在全球碳循环作用的科学理解。本文以我国北方典型的温带植被类型长白山阔叶红松林为研究对象，利用观测塔上的涡动相关系统对长白山阔仆卜红松林进行长期的CO2通量监测，并分析CO2通量的周年动态，估算森林净生态系统生产力；同时基于测树学方法，进行群落调查，根据已有的经验公式，估算森林净生态系统生产力，综合评价长白山阔汗卜红松林碳收支，为森林碳收支的研究提供基础。主要结论有：（1）FSAM模型的分析结果表明，观测塔上40m高度的涡动相关仪器测量的信息中，76％来自于西北至西南方相对均质的阔叶红松原始林，其中footprint最大的源区在塔西南方100m-400m范围内。因此，森林群落调查选择在此区内进行，使得涡动相关法和测树学方法估算的生产力具有可比性。（2）2003-2004年碳通量季节变化趋势基本一致，从年初到4月上旬该森林生态系统保持较弱的正的碳通量（释放CO2），5月开始表现为净的碳吸收，且吸收量迅速增加，到6月达到最大值，然后又逐渐减小；9月末到10月末随着生长季的结束，净生态系统COZ交换（NEE）开始由负转为正，11-12月NEE为正，生态系统以呼吸为主。净生态系统COZ交换的年累计量表明长白山阔叶红松林为明显的碳汇，2003年和2004年净生态系统生产力NEP分别为-217±75gcm-2a-1和-190±85gcm-2a-1，相当于-2.17±0.75tCha-1a-1和-1.90±0.85tCha-1a-1。（3）根据经验公式和材积法得到阔汗卜红松林的生物量在343．9-362．3tha－l之间，应用两种方法得到2003一2004年群落的净初级生产力在10.22-10.40tCha-1a-1之间，净生态系统生产力在2.50±1.12tCha-1a-1-2.68±1.20tCha-1a-1之间。（4）测树学方法与涡动相关法测得的净生态系统生产力略有差异，但在误差有效范围内基本一致。

Initiation and development of water film by seepage

When water seeps upwards through a saturated soil layer, the soil layer may become instability and water films occur and develop. Water film serves as a natural sliding surface because of its very small friction. Accordingly, debris flow may happen. To investigate this phenomenon, a pseudo-three-phase media is presented first. Then discontinuity method is used to analyze the expansion velocity of water film. Finally, perturbation method is used to analyze the case that a water flow is forced to seep upwards through the soil layer while the movement of the skeleton may be neglected relative to that of water. The theoretical evolutions of pore pressure gradient, effective stress, water velocity, the porosity and the eroded fine grains are obtained. It can be seen clearly that with the erosion and re-deposited of fine grains, permeability at some positions in the soil layer becomes smaller and smaller and, the pore pressure gradient becomes bigger and bigger, while the effective stress becomes smaller and smaller. When the effective stress equals zero, e.f. liquefaction, the water film occurs. It is shown also that once a water film occurs, it will be expanded in a speed of (U)(t)/(1 - E >).

Characteristic rainfall for warning of debris flows

A characteristic rainfall is introduced to overcome the difficulties encountered in determining a critical rainfall value for triggering debris flow. The characteristic value is defined as the rainfall at which debris-flow occurrence probability shows a rapid increase, and can be used as a warning rainfall threshold for debris flows. Investigation of recorded debris flows and 24-hour rainfall data at Jiangjia basin, Yunnan Province, in southwestern China, demonstrates the existence of such a characteristic rainfall. It was found that the characteristic rainfall corresponds to the daily rainfall of 90% cumulative probability by analyzing the basin's daily rainfall histogram. The result provides a simple and useful method for estimating a debris-flow warning rainfall threshold from the daily rainfall distribution. It was applied to estimate the debris-flow warning rainfall threshold for the Subaohe basin, a watershed in the 2008 Wenchuan earthquake zone with many physical characteristics similar to those of the Jiangjia basin.

Aspergillus sp136抗细菌耐药活性成分研究

基于广谱抗细菌耐药性这一思路，本研究中心建立了一套抗细菌耐药性化合物的筛选方法。由此从3000多种西南地区特殊生境的微生物和植物样品提取物中筛选获得17个抗细菌耐药性活性样品。对其中一株来自峨嵋山土样的微生物（Aspergillus sp136）进行了深入研究。通过TLC自显影等方法从其发酵产物中追踪分离得到抗耐药有效成分，并鉴定为烟曲霉酸。 采用多种方法对烟曲霉酸的体外抗细菌耐药活性进行评价。在平板扩散法中，烟曲霉酸表现出对青霉素（β-内酰氨抗生素）的协同抗耐药能力，其活性大约3倍于克拉维酸。在MIC的测试实验中，烟曲霉酸表现出对青霉素（β-内酰氨抗生素）以及非β-内酰氨抗生素如红霉素、四环素、氯霉素、链霉素、卡那霉素、庆大霉素的抗耐药能力。在棋盘格杀菌以及时间致死曲线的研究中，烟曲霉酸也表现出对青霉素、红霉素、四环素的协同抗细菌耐药活性。 在广泛的活性筛选中发现烟曲霉酸对LDLR基因具有上调活性，表明烟曲霉酸可能具有降血脂的活性。 在研究中发现，同空白对照相比，烟曲霉酸使耐药菌（Bacillus cereus NCPF63509）细胞外β-内酰胺酶酶活大幅度下降，而细胞内β-内酰胺酶酶活仅略有上升，这表明烟曲霉酸对β-内酰胺酶分泌过程具有抑制作用。 综述了β-内酰胺酶的研究进展。 A two-step agar diffusion method was established to screen wide spectrum synergistic antibacterial agents. By using this method, 17 active samples against antibiotic resistance were discovered from more than 3000 plants and microbes, which were collected from southwest china. One isolate Aspergillus sp136 collected from E-mei mountain area was selected for further studies. From the metabolites of this strain, a synergistic antibacterial compound was isolated by bioautographic TLC assay-guided fractionation and identified as helvolic acid. The synergistic effect of helvolic acid was confirmed by several methods in vitro. The synergistic effect of helvolic acid with penicillin (β-lactam antibiotics) was about 3 times as that of clavulanic acid with penicillin in agar diffusion assay. In MIC studies, helvolic acid exhibited synergistic effects with β-lactam antibiotics such as penicillin and non β-lactam antibiotics such as erythromycin, tetracycline, kanamycin, streptomycin and gentamycin. In checkerboard and time-kill studies, helvolic acid also exhibited synergistic effects with penicillin, erythromycin and tetracycline. In general screen of bioactivities, helvolic acid upregulate LDLR gene, which was indirectly determined by the activity of fluorescent enzyme. Therefore, helvolic acid might have the ability to lower lipid in blood. Compared with blank control, the extracellular β-lactamase activity decrease significantly and the intracellular β-lactamase activity increase slightly in Bacillus cereus NCPF63509 in the presence of helvolic acid, indicating that the secretion of β-lactamase was inhibited by helvolic acid. The research of β-lactamase was reviewed.

川西亚高山云杉人工林天然更新与生境异质性研究

川西亚高山针叶林是四川森林的主体，是长江上游重要的生态屏障。云杉作为亚高山针叶林人工更新的主要树种，已经在该地区形成了大面积的人工纯林。目前，许多云杉人工林分已经进入更新成熟龄，而这些人工林的持续更新却成为日益凸现的问题。探讨这些云杉人工林的自我更新潜力及云杉种子种群更新特点，可为培育后续森林资源提供科学依据。 本文以川西米亚罗亚高山60a云杉人工林为研究对象，并以该区域内相对稳定的植被群落——天然林为对照，采用种子收集器、土壤种子库筛选、室内外种子萌发实验及野外幼苗调查等方法，从异质性微生境的角度研究了种子雨下落之后，不同微生境对种子库、种子萌发、幼苗建立及分布这一前期更新过程的影响，得出如下结果： 1、通过对川西亚高山60a云杉人工林和天然林6年内种子雨雨量、形态特征、散步动态等的持续观测和综合比较可以发现，云杉林结实特点由于林木自身的特征存在着巨大的变动，2002年和2006年两个种子结实大年内，60a人工林种子雨强度分别达到1088.2 ± 52.3粒/m2和704.3 ± 48.9粒/m2，远大于天然林579.9 ± 28.9粒/m2 和507.5± 30.7粒/m2；且云杉林结实质量优于天然林。60a人工林结实量大，种子质量也最好，相对天然林来说对种群的天然更新以及群落的演替都有最大的贡献潜力。应该说，在川西亚高山云杉人工林的天然更新过程中，种源不是影响天然更新的因素。在种子结实大年里，达到更新成熟的云杉人工林有着优于该地区相对稳定植被群落——天然林的种源优势。至少在种子结实大年，种子供应不是该区域人工林天然更新的限制因子。 2、相对于天然林种子库，人工林种子库在种子萌发前能够有较多的有活力种子。虽然这其中有种子雨输入量有差别的因素存在，但两种林分种子库对种子的保存率的不同才是造成这种差异的主要因素。在人工林中，不同地被类型形成的微生境显著地影响了种子库中种子的密度、垂直分布。有地被物存在的微生境能够将种子雨的大部分截留在地被层中，成为幼苗出现的主要场所；同时不同的地被物对种子的保存情况存在显著的差异，苔藓和凋落物层能都较好地保持其中的种子，到种子萌发前，这两种种子库类型能分别为天然更新提供366.1粒/m2和302粒/m2的有效种子。从这点来看，林下地被物上的种子库能够为天然更新萌发阶段提供数量可观的物质基础。 3、种子的萌发和幼苗的定居是天然更新过程中种子库向幼苗库转化的关键环节。总的说来，米亚罗人工林区60a云杉人工林种子向幼苗的转化率十分低下，凋落物、苔藓、草本、裸地四种主要地被物以及天然林内种子/幼苗的转化率分别仅为2.22%、2.14%、0.57%、0.67%、1.05%。这种低的转化率成为云杉林天然更新的限制性因子。但在现有更新条件下，微生境对这一环节仍然显示出十分显著的影响，表现为凋落物和苔藓对现有更新的新幼苗的保存率高于其它类型及天然林。苔藓和凋落物在种子萌发，幼苗保存，以及幼苗分布上都要优于其它地被物类型；另外，微地形对天然更新过程的影响也很显著，凹立地上更适宜于种子的汇集、萌发和定居。 Subalpine coniferous forests dominate most parts of the forested areas in western Sichuan, and they are important ecological barriers in the upper reaches of the Yangtze River. Picea asperata is one of the keystone spruce species for re-afforestation after felling of the natural forests and there have been a total of ca. 13 000 ha of plantations dominate by this species established. Nowadays, many P. asperata plantations have reached reproductive maturity. However, continued regeneration becomes to an important problem in these plantations. Understanding their self-regeneration potential and the regeneration characteristics of seed populations in spruce plantations of these plantations can have some insights on the management of these plantations and the establishment of following forest resources. A subalpine 60a P. asperata plantation distributed in Miyaluo artificial forest area was studied in this paper, at the same time. Synchronously, a 150a natural spruce forest was studied as comparison. Using seed collecting traps, sieving method for soil seed bank, seed germination experiments and seedling investigations in the field, the effects of heterogeneous microsites on early natural regeneration processes after seed rain were studied, which included seed banks, seed germination, seedling establishment and distribution. The main results are as follows. 1. Through a 6-year long term investigation of seed rain intensities, characteristic, dispersal dynamics of 60a P. asperata plantation, we could concluded that the seed setting properties of 60a P. asperata plantation have a great variation for the characteristics trees. In the mast seed year of 2002 and 2006, the seed rain intensities of plantation was 1088.2 ± 52.3 seeds/m2 and 704.3 ± 48.9 seeds/m2 respectively, which were much greater than that of natural spruce forest (579.9 ± 28.9 seeds/m2 in 2002, and 507.5± 30.7 seeds/m2 in 2006). Furthermore, the quality of seed rain in P. asperata plantation was better than that of natural spruce forest. Contrasting with natural spruce forest, 60a P. asperata plantation has a greater potential on natural regeneration of P. asperata population and succession of community for the reason of greater seed rain intensities and better seed quality. We can confirm that seed source was not a limiting factor which influences the natural regeneration progress of P. asperata population distributed in subalpine mountain zone, at least in the mast seed year. 2. Contrasting with natural spruce forest, P. asperata population had more viable seeds in seed bank before the germination. Although the difference of seed rain intensities of two forests has effect on this phenomenon, the difference of seed conservation ability in two forests was the main factor. In the P. asperata plantation, the seed densities and seed vertical distribution pattern were significant effected by the microsites, which posed by different ground cover types. In other word, Microsite with ground covers can obstruct most seeds and keep them in ground cover layer from seed rain, and these ground covers would be the main site for seed occurrence. There was a significant difference about seeds conservation ability among these ground covers. Litter and moss could better conserve P. asperata seeds which distributed in this two covers. Seed banks exist in litter and moss ground cover types could respectively provide 302seed/m2 and 366.1seed/m2 for natural regeneration before the seed germination. From this point of view, we could conclude that ground covers can ensure considerable numbers of seeds for the germination process. 3. Seed germination and seed establishment are key steps that the seeds invert to seedlings in natural generation process. In sum, the seed/seeding transform rate in 60a P. asperata plantation distributed in Miyaluo artificial forest area is very low. the seed/seeding transform rates in litter, moss, herb, soil surface and natural spruce forest were 2.22%、2.14%、0.57%、0.67%、1.05%, respectively. The low transform rate become to a limiting factor of P. asperata natural regeneration process. However, under the existing conditions of natural regeneration, microsit still had significant effect on this transform. The states of Seed germination, new seedling conservation, and older seedling distribution in litter and moss were better than in any other ground cover type or natural spruce forest. In addition, the micro-relief has significant effect on natural regeneration process. Concave site was more suitable for seed collection, seed germination and seedling distribution.

增温对川西北高寒草甸植物群落结构及几种主要植物生长和生理的影响

由于人类活动所引起的地球大气层中温室气体的富集已导致全球地表平均温度在20世纪升高了0.6 ℃，并预测在本世纪将上升1.4-5.8 ℃。气候变暖对陆地植物和生态系统影响深远，并已成为全球变化研究的重要议题。高海拔、高纬度地带的生态系统对气候变化最敏感。而在高原和高山极端环境影响下所形成的高寒草甸生态系统极其脆弱，对由于温室效应引起的全球气候变化极其敏感，对这些变化的响应更具有超前性。 本研究以川西北高寒草甸植物群落及几种主要物种为研究对象，采用国际山地综合研究中心（ITEX）普遍所采用的增温方法-----开顶式生长室（OTC）模拟气候变暖来研究增温对高寒草甸植物群落结构、物质分配及其主要物种生长和生理的影响，以探讨高寒草甸植物响应与适应气候变暖的生物学和生态学机制。主要研究结论如下： 1、OTC的增温效果 由于地温、地表温度和气温的平均值在OTC内分别高出对照样地0.28℃、0.46℃和1.4℃，这说明本研究所采用的开顶式生长室（OTC）起到了增温的作用；同时，由于温室内与温室外接受的降水量相同，温室内由于热量条件的改善，土壤蒸发和植被的蒸腾作用增强，直接导致了OTC内土壤表层相对湿度的减少。 2、群落结构对增温的响应 由于增温时间较短，增温内外样地的物种组成并未发生改变；但增温后一定程度上改变了植物群落的小气候环境，从而导致物种间的竞争关系被破坏，种间竞争关系的破坏引起群落优势种组成发生相应的改变，在对照样地，鹅绒委陵菜、甘青老鹳草、遏蓝菜和蚤缀是占绝对优势的物种，而在OTC内，小米草、尼泊尔酸模、垂穗披碱草、发草和羊茅的重要性显著增加。 禾草和杂草由于对增温的生物学特性及其资源利用响应的不同，加之增温造成土壤含水量下降等环境因子的改变。与对照样地相比较，OTC内禾草的盖度及生物量都显著增加，而杂草的盖度和生物量则显著下降。 3、植物生长期对增温的响应 OTC内立枯和调落物的生物量在生长季末（10月份）都要小于对照样地的立枯和调落物生物量，而OTC内的地上鲜体生物量在10月份却略高于对照样地。这说明OTC内植物的衰老或死亡得以延缓，而植物的生长期得以延长。 4、群落生物量及分配对增温的响应 OTC内的地上鲜体生物量(10月份除外)和地下0-30cm的根系生物量与对照样地相比较，都出现了不同程度的减少；土壤根系的分配格局也发生了明显的改变，其中，OTC内0-10cm土层的生物量分配比例增加，而20-30cm土层生物量分配比例的减少。 5、群落碳、氮对增温的响应 增温后，OTC内植物群落地上活体和地下活根的碳浓度不同程度的高于对照样地，植物群落的碳库在OTC内也略高于对照样地；而OTC内植物群落地上活体和地下活根的氮浓度不同程度的低于对照样地，其植物群落的氮库与对照样地相比也略有下降。 6、几种主要植物的生长及物质分配对增温的响应 垂穗披碱草在增温后株高、比叶面积和地上生物量均显著地增加；尼泊尔酸模在增温后比叶面积和单株平均生物量积累显著地增加，而各组分中，增温处理使叶的生物量显著增加，而根的生物量却显著下降；鹅绒委陵菜在增温后株高、比叶面积和单株平均生物量积累显著地减少，而各组分中，增温处理使叶和茎的生物量显著减少，根的生物量却显著地增加。 尼泊尔酸模的LMR、RMR、R/S、根部碳含量、碳和氮在叶片与根部的分配比例在增温后显著地增加，而SMR、根部氮含量、碳和氮在茎部的分配比例在增温后却显著地降低；鹅绒委陵菜的RMR、R/S、碳和氮在根部的分配比例在增温后显著地增加，而SMR、LMR、碳在叶片的分配比例在增温后却显著地降低 7、几种主要植物的光合生理过程对增温的响应 增温使垂穗披碱草和尼泊尔酸模叶片中的叶绿素a、叶绿素b、总叶绿素含量显著增加；而鹅绒委陵菜叶片的叶绿素a、叶绿素b、总叶绿素含量在增温后显著减少，类胡萝卜素含量在增温后却显著增加。 增温对3种植物的气体交换产生了显著影响。其中，垂穗披碱草和尼泊尔酸模叶片的光响应曲线在增温后明显高于对照处理，A、E、gs、Pmax、、Rday、AQY和LSP显著增加，而LCP则显著降低；鹅绒委陵菜的光响应曲线在增温后则明显的低于对照处理，A、E、gs、Pmax、、Rday、AQY和LSP显著减少，而LCP则显著增加。 增温后垂穗披碱草和尼泊尔酸模叶片的Fv/Fm、Yield和qP显著增加；而鹅绒委陵菜叶片的Fv/Fm、Yield和qP则显著减少，qN却显著地增加。 8、几种主要植物的抗氧化酶系统对增温的响应 增温使垂穗披碱草和尼泊尔酸模体内抗氧化酶活性和非酶促作用有所提高，植物膜脂过氧化作用降低；鹅绒委陵菜叶片中酶促反应和非酶促反应在增温后也显著提高，但可能由于增温后的土壤干旱超过了鹅绒委陵菜叶的抗氧化保护能力，抗氧化酶活性及非酶促反应（脯氨酸、类胡萝卜素）的提高不足以完全清除干旱诱导形成的过量活性氧，因此叶片的膜脂过氧化程度仍然显著提高。 Enrichment of atmospheric greenhouse gases resulted from human activities such as fossil fuel burning and deforestation has increased global mean temperature by 0.6 ℃ in the 20th century and is predicted to increase in this century by 1.4-5.8 ℃. The global warming will have profound, long-term impacts on terrestrial plants and ecosystems. The ecoologcial consequences arising from global warming have also become the very important issuses of global change research. The terrestrial habitats of high-elevation and high-latitude ecosystems are regarded as the most sensitive to changing climate. The alpine meadow ecosystme, which resulted from the composite effects of mountain extreme climatic factors in Tibetan Plateau, is thus thought to be especially vulnerable and sensitive to global warming. In this paper, the response of plant community and several main species in the alpine meadow of Northewst Sichuan to experimemtal warming was studied by using open-top chambers (OTC). The aim of the this study was to research the warming effects on plant community structure, substance allocation, growth and physiological processes of several mian species, and to explore the biological and ecological mechanism of how the alpine meadow plants acclimate and adapt to future global warming. The results were as follows: 1. Warming effects of OTC The mean soil temperature, soil surface temperature and air temperature in OTC manipulation increased by 0.28℃、0.46℃ and 1.4℃ compared to the control during the growing season. This suggested that the OTC used in our study had increased temperature there. Meanwhile, the OTC manipulation slightly altered thermal conditions, but the same amount of precipitation was supplied to both the OTC manipulation and the control, so higher soil evaporation and plant transpiration in OTC manipulation directly lead to the decrease of soil surface water content. 2. The reponse of community structure to experimental warming The species richness was not changed by the short-term effect of OTC manipulation. However, experimental warming changed the microenvironment of plant community, therefore competitive balances among species were shift, leading to changes in species dominance. In the present study, the dominant plant species in the control plots were some forbs including Potentilla anserine, Geranium pylzowianum, Thlaspi arvense and Arenaria serpyllifolia, however, the importance value of some gramineous grasses including Elymus nutans, Deschampsia caespitosa, Festuca ovina, and some forbs including Euphrasia tatarica and Rumex acetosa significantly increased in OTC. The different biology characteristics and resource utilizations between gramineous grasses and forbs, and enhanced temperature caused change in some environment factors such as soil water content. As a result, the coverage and biomass of gramineous grasses significantly increased in OTC compared to the control, however, the coverage and biomass of forbs singnifciantly decreased in OTC compared to the control. 3. The reponse of plant growing season to experimental warming Both the standing dead and fallen litter biomass in OTC were lower than those in the control in October, and the biomass of aboveground live-vegetation in OTC was higher than that of the control. The results indicated that the senescence of plants was postponed, and the growing season was prolonged in our research. 4. The reponse of community biomass accumulation and its allocation to experimental warming Experimental warming caused the decrease of aboveground live biomass and belowground root biomass except for the aboveground live biomass in October. Experimental warming also had pronounced effects on the pattern of root biomass allocation. In the present study, the root biomass in 0-10cm soil layer increased in OTC manipulation compared to the control, however, the root biomass in the 20-30cm soil layer decreased in OTC manipulation compared to the control. 5. The reponse of community C and N content to experimental warming The C concentration and stock in aboveground live and belowground root both increased in OTC manipulation compared to the control. However, the N concentration and stock in aboveground live and belowground root both decreased in OTC manipulation compared to the control. 6. The reponse of gowth and biomass, C and N alloction of several species to experimental warming Experimental warming significantly increased the height, SLA (specific leaf area) and aboveground biomass of Elymus nutans in OTC manipulation compared to the control. The SLA and total biomass of Rumex acetosa also significantly increased in OTC manipulation compared to control, among the different components of Rumex acetosa, leaf biomass significantly increased, but root biomass significantly decreased in OTC manipulation compared to the control. However, the height, SLA and total biomass of Potentilla anserina significantly decreased in OTC manipulation compared to the control, among the different component of Potentilla anserina, leaf and stem biomass significantly decreased, but root biomass significantly increased in OTC manipulation compared to the control. The LMR (leaf mass ratio), RMR (root mass ratio), R/S (shoot/root biomass ration) and root C concentration of Rumex acetosa significantly increased in OTC manipulation compared to outside control, also, Rumex acetosa allocated relatively more C and N content to leaf and root in response to experimental warming, however, the SMR (stem mass ration) and root N concentration of Rumex acetosa significantly decreased in OTC manipulation compared to outside control, also, Rumex acetosa allocated relatively less C and N content to stem in response to experimental warming. The RMR and R/S of Potentilla anserina significantly increased in OTC manipulation compared to outside control, also, Potentilla anserina allocated relatively more C and N content to root in response to experimental warming, however, the SMR and LMR of Potentilla anserina significantly decreased in OTC manipulation compared to outside control, also, Potentilla anserina allocated relatively less C and N content to leaf in response to experimental warming. 7. The reponse of physiological processes of several species to experimental warming Experimental warming significantly increased chlorophyll a, chlorophyll b and total chlorophyll of Elymus nutans and Rumex acetosa in OTC manipulation compared to outside control. However, chlorophyll a, chlorophyll b, total chlorophyll and carotenoid of Potentilla anserina in OTC manipulation significantly decreased compared to outside control. Experimental warming had pronounced effects on gas exchange of Elymus nutans, Rumex acetosa and Potentilla anserine. In the present study, warming markedly increased the light response curves of Elymus nutans and Rumex acetosa in OTC manipulation compared to outside control, and also singnificantly increased A (net photosynthesis rate), E (transpiration rate), gs (stomatal conductance), Pmax (maximum net photosynthetic rate), Rday (dark respiration rate), AQY (apparent quantum yield) and LSP (light saturation point), but LCP (photosynthetic light compensation) of Elymus nutans and Rumex acetosa in OTC manipulation singnificantly decreased compared to outside control. However, warming markedly decreased the light response curves of Potentilla anserina in OTC manipulation compared to outside control, and also singnificantly decreased A, E, gs, Pmax, Rday, AQY and LSP, but LCP of Potentilla anserina in OTC manipulation singnificantly increased compared to outside control. Experimental warming singnificantly increased the chlorophyll fluorescence kinetics parameters such as Fv/Fm, Yield and qP of Elymus nutans and Rumex acetosa and qN of Potentilla anserina in OTC manipulation, but Fv/Fm, Yield and qP of Potentilla anserina in OTC manipulation singnificantly decreased. 8. The reponse of antioxidative systems of several species to experimental warming Experimental warming tended to increase the activities of antioxidative enzymes and stimulate the role of non-enzymes of Elymus nutans and Rumex acetosa. As a result, MDA content of Elymus nutans and Rumex acetosa decreased. The activities of antioxidative enzymes and non-enzymes of Potentilla anserina also significantly increased in OTC manipulation, but more O2- was produced because of lower soil water content, and the O2- accumulation exceeded the defense ability of antioxidative systems and non-enzymes fuctions. As a result, MDA content of Potentilla anserine still increased in OTC manipulation compared to outside control.

青藏高原东部混农季节性放牧及其对高山林线格局的影响

混农季节性放牧（agropastoral transhumance）通过作物种植和畜牧生产相结合的方式对不同海拔高度带上的资源进行相互补充利用，在亚洲兴都库什地区、青藏高原、横断山、东部及南部非洲、南美安第斯地区等具有悠久的历史。这种传统的生计系统几千年以来一直是居住在该地区的人类社会和自然生态系统相互作用的主要形式之一。这种传统的资源利用方式与山地自然植被以及特殊的山地人类文化和社会特征具有密切的协同演变关系。认识和理解这一关系，是山地生态学和人类学的核心科学问题之一。近年来，山地生态系统的多重功能性及动态演变对山区社会经济可持续发展的重要意义受到人们的不断关注。本文通过对云南省德钦县的12个自然村的混农季节性放牧以及对云南德钦、四川壤塘等山地植被格局特别是高海拔地带植被格局的的详细调查，探讨青藏高原东缘地区混农季节性放牧的主要特征、系统构成及相互关系，及其在全球变化、经济全球化和市场化及现代化过程中的变化趋势，分析混农季节性放牧与高山林线格局及生态系统的互动关系，旨在探讨山地地区人类活动与自然生态系统之间的互动关系，从而为山区社会经济可持续发展、环境建设和生物多样性保护等国家战略提供理论依据。 调查结果表明，混农季节性放牧是一种适应青藏高原东部高山峡谷地区环境因子及自然资源呈明显的垂直分布、资源数量稀少而时空分布异质性极高的生存环境的一种传统经济形式。这种传统的畜牧业的主要生产目的仍然是提供当地基本生存所需的产品，饲养牲口的种类和数量取决于农户的当地需求并且受资源的限制，因而维持在比较低的水平的。分布在不同海拔高度的放牧资源在一年中被牲口利用的时间也不同，互为补充，共同构成混农季节性放牧的资源基础。根据各社区永久居住点的位置和该村的土地资源特别是牧草地资源的分布范围，牲口迁移的距离和格局有较大的差异。。天然牧场仍然是最主要的畜牧业生产资源。混农季节性放牧中的农业系统和牧业系统互为补充，共同构成调查地区完整的的生计系统，农耕活动为放牧活动提供精饲料如粮食等和冬季饲料如秸秆， 其数量往往成为家庭畜牧业生产规模的主要决定因子之一。 通过对牲口数量和结构、牲口的时空迁移格局、牧业活动在整个经济活动中的相对重要性以及牧业活动和作物种植的关系方面的研究分析，混农季节性放牧在近几十年发生了深刻的变化。主要表现在牲口数量总体下降，牲口组成发生变化，牲口移动性降低、牧业活动的经济重要性下降以及牧业活动和种植活动之间的相互依存度降低等。上述变化的根本驱动力是发生在当地、地区及全球尺度上的环境、政治、社会经济、技术和文化等的变化，从而造成当地群众畜牧生产目标、土地利用和劳动力的分布等发生了变化。当地生计系统发生的改变可能会带来对方面而深刻的政治、社会经济、文化和生态影响。 混农季节性放牧这种古老的传统生计策略面临着许多挑战，如冬季饲料短缺、草场退化、缺乏市场竞争力、经济重要性降低、对年轻人缺乏吸引力、国家缺乏专门的政策指导等。与此同时，经济全球化、市场经济、新技术的应用、替代生计机会的增加、国家对于山地生态系统的作用的重新定位等也为传统生计系统转型、实现社会与生态共赢创造了机遇。 混农季节性放牧活动对亚高山及树线交错带生态系统系统的互动方式主要体现在以下几个方面：（1）牲口啃食、践踏等影响森林群落更新，改变森林群落的组成和结构，从而影响森林群落的演替进程和植被格局。林线边缘是搭建夏棚的首选地点，因此林线及树线交错地带就成了牲口活动的主要场所之一；（2）利用火烧开辟、维持和改良高山牧场； 3）在亚高山火灾迹地的放牧活动能够阻止火烧迹地的顺向演替； 4）牧民在林线附近获取建材和薪材等活动影响高山林线附近森林的结构和功能。 在调查区域，梅里雪山、白马雪山、甲午雪山的林线海拔高度在4200-4300m之间； 四川雅江、理塘一线，林线位置多在4300-4400m；四川壤塘二林场一带的林线主体在4100-4200m，在个别地区达到4300m； 在贡嘎山的南坡和东坡一带，林线位置在3600-3700m；而在四川松潘一带，林线位置主体在3700-3800米左右。树线高度的分布趋势和林线一致。混农季节性放牧及其有关人类利用活动使研究地区很多地方高山林线降低、树线交错带宽变窄或消失。在研究地区，总体情况是，阳坡和半阳坡（南坡、西南坡等）的林线和树线比阴坡和半阴坡（北坡、东北坡等）低，变化幅度达20-200m。这种差异主要是为了开辟牧场而人为清除了南向坡自然林线及其以上的植被从而使林线位置下降所致。在南坡自然林线保留得比较好的地方，林线和树线依然可以达到甚至超过北坡林线和树线的高度。放牧活动抑制了高山林线带火烧迹地的天然更新，从而使林线位置保持在目前的位置。 放牧活动对高山林线带森林群落更新的影响是显著的。自然林线内的乔木个体密度特别是新生苗和幼苗的密度大大高于非自然林线。没有放牧的自然林线及树线交错带内的I级个体（新生苗）密度达到725-2917株/公顷，而与之相对的处理样地内I级个体的密度只有0-228株/公顷；II级个体（高度10-50cm）也表现出类似的趋势，在没有放牧的自然林线及树线交错带样方内，其密度达到550-5208株/，而在放牧处理样方内只有14-321株/公顷。在非自然林线带样地内，在有正常放牧的样地内，完全缺乏I级个体。 从相对比例来看，没有放牧的样方内的I、II级个体在全部个体中所占的比例显著高于有放牧活动的样方。放牧使林线交错带的乔木幼苗数量显著减少，从而影响林线及树线交错带森林群落的天然更新过程。林线和树线交错带的灌木对乔木幼苗具有重要的保护作用，能够为树线树种如冷杉等幼苗的定居体提供有利的微气候环境，同时保护苗免受牲口的啃食和践踏。火烧以后接着进行放牧能够100%地抑制高山林线带的幼苗更新。 高山牧场放牧强度降低、使用时间缩短而低海拔地带放牧强度增加是研究地区混农季节性放牧系统的一个显著变化。这种变化也必然会引起各海拔带上的生态系统的变化。放牧强度的降低、生产性用火的停止将导致原来通过人工火烧而降低并通过进一步的火烧和放牧活动来维持的林线及其以上地带的灌木盖度和高度的增加，从而为林线森林群落的扩张创造条件。 青藏高原东部高山峡谷地区是我国重要的山地生态系统，在我国的生物多样性保护、生态环境建设、社会经济可持续发展战略中具有举足轻重的作用。正确认识人类特别是当地传统的生计系统与生态环境系统的互动关系是实现上述战略目标的前提。决策者必须以综合、系统的的视角协调促进社会经济可持续发展、保护生物及文化多样性和维持人、牲口和生态系统之间的平衡的多重目标。 Agropastoral transhumance, which makes a complementary exploitation of the natural resources at different altitudinal belts through a combination of migratory animal husbandry and crop cultivation, has a long history in Hindu-Kush Himalaya, Tibet Plateau, Hengduan Ranges, eastern and southern Africa and the Andes region of south America.For millennia, this traditional livelihood strategy has been one of the main forms of interaction between human societies inhabiting in these regions and their natural ecocystems. A close co-evolutionary relationship has been developed between this indigenous resources management systems and the mountain vegetation systems on the one hand and a unique set of cultural values and social features on the other. Understanding this relationship has been one of the core scientific issues in mountain ecology and anthropology. In recent years, the importance of the multiple functions of the mountain ecosystems and their dynamic changes in the sustainable socio-economic development of the mountain regions has gained increasing attention. This paper, which is based on a detailed study on the agropastoral practices of the 12 natural villages in Deqin County of Yunnan, and the mountainnn vegetation patterns in Deqin of Yunnan and Rangtang County of Sichuan, intends to reveal the major characteristics, system composition and the inter-relations of the subsystems of the agropastoral transhumance in Eastern Tibetan Plateau as well as the trends of changes of the system within the context of global changes, economic globalization and modernity process of China and analyze the relations between agropastoral transhumance and alpine ecosystem, ao as to understand the interactions between human activities and natural ecosystems of the mountains and provide theoretical basis for the national strategies in eocioeconomic development, environmental reconstruction and biodiversity conservation in the mountain regions. Results of the survey indicate that agropastoral transhumance in the investigated area is a traditional economic form that is highly adapted to the eastern Tibet Plateau where the topography features high peaks and deep gorges and where the highly variable environmental parameters and scanty natural resources exhibit a distinct vertical spectrum of distribution and great temporal and spatial heterogeneity. The main objective of pastoral management is still aimed at the production of basic goods and services of local people and thus the type and size of animals raised for each household mainly depend on local needs and are limited by the availability of natural resources. The scale of production is relatively low. Pastoral resources at different altidudinal belts are complementarily used at different seasons of a year and thus form the resources basis for agropastoral production of the study area. Migration distances and patterns vary with the location of the permanent settlements, the elevational distribution range of the resources of the villages concerned. Natural pastures (rangelands) are the main fodder resources and sumplement feedings only account for less than 5% of the total fodder consumption. Crop cultivation and pastoral activities support each other to form a complete livelihood system. The ability of the farmig lands (crop cultivation) to provide the pastoral activities with concentrates and sumplements often becomes a main factor limiting the scale of livestock production at household level. Agropastoral transhumance is experiencing drastic changes in recent decades as is reflected in the size and composition of animals, the seasonal migration pattern, the relative importance of pastoralism in the household economy and the interplays of agricultural and pastoral elements of the system. In general, there is a decline in animal population and mobility, a shift in animal composition to meet new needs arising from changed macro-economic situation, a decrease in the relative importance in the household economy and an increasing decoupling of agro&pastoral relations. The fundamental divers of these changes can be traced to environmental, social, economic, technological and cultural changes from local to global levels and such changes have further caused local changes in livestock management objectives, land use and distribution of labor forces. Changes in local livelihood systems could have profound political, socioeconomic, cultural and ecological conseuquences. Agropastoral transhumance, as an age-old traditional livelihood strategy, is facing multifacet challenges, such as winter fodder shortage, rangeland degradation, lack of market competitiveness, decrease in economic importance, lack of appreciation among the young generation and adequate policies from the government. At the same time, economic globalization, market economy, intrdoctution of new technologies, increase of alternative income generating opportunities and the national re-oreitation of policies on mountain ecosystems have all brought about new opportunities for the transformation of the traditional livelihood system and the synchronized development of local society and the environment. Agropastoral transhumance interacts with the ecosystems at the timberline and treeline ecotone mainly through the following aspects: 1)Animal browsing and stamping affect the regeneration process of the forest communities and alters the composition and structure of the forest which in turn affect the succession process and vegetation pattern of the forest communities. Forest edges are the priority locations for summer houses and therefore the timeline and treeline area becomes the major venues of aninal activities; （2）herders create, maintain and improve pastures through burning that remove the forest communities at the timeline and treeline ecotone; 3）immediate grazing on the fire sites can significantly prevent the fire sites from perogressive succession; and 4）herders harvesting of construction timber and firewoods affects the structure and functions of the forest communities at the timberline and treeline zone. Timberline position in the survey region shows geographical variations. It is around 4200-4300m in Meilixueshan, Baimaxueshan and Jiawuxueshan in Northwest of Yunnan and rises to 4300-4400m in Yajiang County and Litang County of Sichuan. In Rangtang of Sichuan, it is between 4100-4200m, though reaching 4300m in localized sites. In the southern and eastern slopes of Gongga Mountain, the timberline is only between 3600m and 3700m and in Songpan County at the upper reach of the Minjiang River the timberline is around 3700-3800m.Treeline pattern follows similar trend. In many places, agropastoral transhumance and related human activities have lowered the timberline and treeline and narrowed or removed the treeline ecotone. In the area of survey, generally speaking, timberlines and treelines are lower on the southern slopes than on the northern slopes, with a difference between 20 and 200m. This is mainly because that the use of fires to crerate pastures has removed the forest vegetation at the previous timberline and above. In fact, in many places, well-preserved forests on the south slopes have even high timberline position that the corresponding northern slopes. At subalpine zone, grazing activities could have prohibited the natural regeneration of many forest fire sites and maintained the forest position at the present level. Grazing has a significant impact on the regernation process of forest communities at the timberline zone. Natural timberline and treeline ecotone has much higher density of treeline species individuals especially the emergents and seedlings than the timberlines that are maintained by human activities. In natural timberline and treelien ecotone without grazing interference, the density of the I Class seedlings (less than 10cm in height) ranges 725-2917 /hm2; while that in the treatment plots (with grazing disturbance) is only 0-228//hm2；II Class seedlings (10-50cm）exhibit similar density trends, reaching 550-5208//hm2 in natural timberline without grazing but only 14-321//hm2 in the plots with grazing treatment. In the man-created timberlines, there is no I Class seedling at all in plots with normal grazing activities. In relative terms, in plots without grazing activities, the propotion of I Class and II Class seedlings is much higher than that in plots with grazing. Grazing activities have significantly reduced the number of seedlings in the timberline ane treeline ecotone, and thus affect the natural regeneration process of the forests. Shrubs at the timberline and treeline ecotone can effectively protect the seedlings from severe climate and animal tramping, thus increasing the survival rate of the seedlings. Grazing following fires can completely inhibit forest regeneration process at timberline. Changes in agropastoral transhumance will have great impact on the timberline and treeline pattern of the studied area. The decrease in grazing intensity on alpine pastrues and the cessation of the use of fires will result an increase in the cover and height of shrubs above the present human-maintained treeline, which will create further condition for the expansion of timberline forest communities. Eastern Tibet Plateau harbors some most important mountain ecosystems of China that are of vital importance to the country’s strategy in biodiversity conservation, environmental construction and sustainable sociaoeconomic development. A proper knowledge of the interactions between traditional livelihood systems and the ecosystems in the region is a precondition to the realization of the above strategic goals. Therefore, the decision-makers must have a holistic and systemic perspective so as to integrate the multiple objectives of promoting sustainable socioeconomic development, conserving biological and cultural diversity and maintaining the balances among people, animal population and the ecosystems.

CO2浓度升高对红桦幼苗生理与生长的影响

大气CO2浓度的增加已经成为不可争议的事实。预计本世纪末大气CO2浓度将增加到约700µmol mol-1。森林年光合产量约占陆地生态系统年光合产量的70%。森林树木是一个巨大的生物碳库，约占全球陆地生物碳库的85%。森林树木对CO2的固定潜力是缓解由大气CO2浓度升高引起的未来全球气候变化问题的决定性因子之一。红桦（Betula albosinensis Burk.）是川西亚高山采伐迹地自然或人工恢复的重要树种。本研究以1a红桦幼苗为模式植物，采用人工模拟的方法，研究CO2浓度升高对不同种内竞争强度（种群水平）下红桦幼苗的生理特征、生长、干物质积累及其分配的影响，探讨在种内竞争生长条件下红桦幼苗的“光合适应机理”与生长特征，为西南亚高山森林生产力对未来全球变化的预测提供重要参考。 本研究的主要结果如下： 1）在种内竞争生长条件下红桦幼苗经过CO2浓度升高熏蒸4个月后，叶片出现“光合适应”现象。与对照相比，低种植密度（28株m-2）和高种植密度（84株m-2）条件下的红桦幼苗净光合速率（A）、气孔导度（gs）、蒸腾速率（E）、表观量子产量（AQY）和羧化速率（CE）显著降低，而水分利用效率（WUE）则显著提高。CO2浓度升高处理的红桦幼苗叶片Rubisco活性、单位叶面积N浓度、叶绿素a、叶绿素b和类胡萝卜素浓度都显著降低。但CO2浓度对红桦幼苗的叶绿素a与叶绿素b的比值没有显著影响。CO2浓度升高显著增加红桦幼苗单位叶面积的非结构性碳水化合物（TNC）浓度，结果是红桦幼苗的比叶面积（SLA，cm2 g-1）显著降低。 2）与对照相比，CO2浓度升高处理的红桦幼苗高、基径、单叶面积和侧枝的相对生长速率（R GR）显著提高，尤其在试验处理的早期。CO2浓度升高既增加单株红桦幼苗总叶片数量又增加单叶面积，结果是单株红桦幼苗的总叶面积比对照显著增加。 3）CO2浓度升高处理显著增加红桦幼苗干物质积累（尤其是细根生物量），改变了红桦幼苗生物量的分配格局。与对照相比，CO2浓度升高处理的红桦幼苗叶重比（LWR）、叶面积比（LAR）、叶根重比（Wl/Wr）和源汇重比（leaf weight to non-leaf weight ratio, Wsource/Wsink）显著下降（高种植密度的LWR除外），而根冠比（R/S）则显著增加。在两种种植密度条件下，CO2浓度升高显著增加红桦幼苗根生物量的分配比率，显著降低叶片的生物量分配比率，对主茎、侧枝以及地上生物量的分配比率不变或约有下降。 总之，长期生长在CO2浓度升高条件下的红桦幼苗光合能力下降，并伴随Rubisco活性、叶N浓度、光合色素浓度的显著降低以及TNC浓度的显著增加。支持树木光合速率下降与Rubisco活性、叶N浓度下降以及TNC浓度增加紧密相关的假设。CO2浓度升高处理红桦幼苗的早期相对生长速率大大高于对照，而后期迅速下降，说明红桦幼苗生物量的显著增加主要归功于CO2浓度升高的早期促进作用和叶面积的显著增加。CO2浓度升高显著增加红桦幼苗根系生物量和根冠比，表明红桦幼苗“额外”固定的C向根系转移。 The steady increae of atmospheric CO2 concentration（[CO2]）has been inevitable fact. Models predict that the atmospheric [CO2] will increase to about 700µmol mol-1 at the end of the twenty-first century. As trees constitute a majoor carbon reservoir–85% of total plant carbon is found in forest, and their ability to sequester carbon is a key determinant of future global change problems caused by increases in atmospheric CO2. In addition to the role of forests in the global carbon cycle, inceased growth could be of economic benefit, for example, offsetting deleterious effects of climatic changes. Betula albosinensis (Burk.) usually emerges as the pioneer species in initial stage and as constructive species in later stages of forest community succession of mountain forest area, and also is one of important tree species for afforestation in logged area, in southwesten China. In this experinment, Betula albosinensis seedling (one-year-old) was used as the model plant. B. albosinensis seedlings were grown under two all-day [CO2], ambient (about 350 µmol·mol-1) and elevated [CO2] (about 700 µmol·mol-1), and two planting densities of 28 plants per m2 and 84 plants per m2. The objectives were to characterize birch mature leaf photosynthesis, growth, mass accumulation and allocation responses to long-tern elevated growth [CO2] under the influences of neighbouring plants, and to assess whether elevated [CO2] regulated birch mature leaf photosynthetic capacity, in terms of leaf nitrogen concentration (leaf [N]), activity of ribulose bisphosphate carboxygenase (Rubisco), Rubisco photosynthetic efficiency, and total nonstructural carbohydrates (TNC) concentration, and also to provide a strong reference to predict the productivity of subalpine forests under the future global changes. The results are as follows: 1) B.albosinensis seedlings exposed to elevated [CO2] for 120 days, photosynthetic acclimation phenomena occurred. At two planting densities, leaves of birch seedlings grown under elevated [CO2] had lower net photosynthetic rate (A), stomatal conductance (gs), transpiration (E), apparent quantum yield (AQY) and carboxylated efficiency (CE) and higher water use efficiency (WUE), compared to those of B.albosinensis seedlings grown under ambient [CO2]. Based on the leaf area, leaf [N], Rubisco activity and photosynthetic pigments concentrations of B. albosinensis seedlings grown under elevated [CO2] were significantly lower than those grown under ambient [CO2]. The ratio of chlorophyll a to chlorophyll b concentration was not affected by elevated [CO2]. Under elevated [CO2], the TNC concentration per unit leaf area significantly increased, resulting in significant decrease in specific leaf area. Thus leaf photosynthetic capacity of B. albosinensis seedlings would perform worse under rising atmospheric [CO2] and the influences of neighbouring plants. 2) Under elevated [CO2], the relative growth rate (RGR) of B. albosinensis seedlings height, basal diameter, a leaf area and branch length significantly increased, especially at the initial stage of exposure to elevated [CO2], and a leaf area and leaf numbers per B. albosinensis seedling also significantly increased. Thus the total leaf area per B. albosinensis seedling was significantly increased under elevated [CO2]. 3) As the increase of RGR and total leaf area, biomass of B. albosinensis seedling grown elevated [CO2] was higher, compared to that of B.albosinensis seedlings grown at ambient [CO2]. Elevated [CO2] changed the biomass allocation pattern of B. albosinensis seedling. At two planting densities, B. albosinensis seedlings grown elevated [CO2] had lower leaf weight to total weight ratio (LWR), leaf area to total weight ratio (LAR) and leaf weight to non-leaf weight ratio (Wsource/Wsink), but higher root weight to shoot weight ratio (R/S), compared to those of B.albosinensis seedlings grown at ambient [CO2]. Under elevated [CO2], roots biomass to total biomass ratio was signigicantly increased, leaves biomass to total biomass ratio was significantly decreased. The main stem and branch biomass to total biomass ratio were not affected by elevated [CO2]. In conclusion, our results supported the hypothesis that the decline in photosynthetic capacity of C3 plants will appear after long-term exposure to elevated [CO2], accompanying with the significant decrease in Rubisco activity, leaf N concentration, photosynthetic pigments concentration, and significant increase in total non-structural carbohydrates concentration. Our results also have shown that the increase of biomass of B. albosinensis seedlings should be attributed to initial stimulation on RGR and total leaf area resulted from elevated [CO2]. Under elevated [CO2], the extra carbon sequestered by B.albosinensis seedlings transferred into under-ground part because of increase in root biomass and R/S.

青藏高原东缘高山林线乔木种群生态特征研究

青藏高原东部分布着世界最高的林线，该区域也是由欧亚北温带物种形成的林线的南界。在大面积野外踏勘的基础上，选择青藏高原东部具有典型高山林线分布的三个地点（滇西北白马雪山、川西北鹧鸪山及岷江源地区）作为研究区，从种群的结构、生存特征、分布格局及分形特征等方面对青藏高原东缘高山林线乔木种群生态学特征进行了研究，并在此基础上探讨了人类活动对林线种群生态特征及林线格局的影响。结果表明，林线区乔木树种多以单种群形式存在，林线区群落结构简单，乔木层多为单一树种组成，其生长型较之郁闭林发生了急剧的变化：树木高度急剧下降，而发展多茎多分枝的生长型。生长型的转变是高山林线乔木对恶劣自然条件的形态适应。 研究发现，在青藏高原东缘，阴坡林线乔木主要是冷杉（Abies spp.），阳坡主要由圆柏（Sabina spp.）组成，少数地方还有云杉（Picea spp.）。阴坡乔木种群结构多表现为增长型，幼苗和幼树在种群中占较大比重，种群潜在自然更新能力较强，但幼龄个体死亡率非常高，存活曲线多接近Deevey-Ⅲ型；阳坡乔木种群幼苗个体数极少，幼树相对增加。野外调查表明，人为活动较频繁的阳坡林线区幼苗数量极少甚至缺失，而受人为活动干扰较小的样地中幼苗和幼树数量明显增多，从一个侧面说明放牧等人类活动可能对林线种群的更新带来较大影响，而对卡卡沟围栏内外的样地分析也进一步证明了这一结果。 所研究林线乔木种群各龄级的空间格局在不同尺度上表现为聚集、随机和均匀分布，以聚集分布为主；各龄级在不同尺度上表现出显著的相关性，幼苗通常与另外两个龄级的关联性较密切。各龄级间显著的相关性表明不同龄级个体在空间交错分布，有利于对各种资源的充分利用，对种群的生存和发展非常有利，反映了高山生态系统恶劣生境中种群的一种适应对策。 林线乔木种群各龄级分布格局的计盒维数有差别，林线种群的计盒维数总是小于郁闭林种群的计盒维数。另外，郁闭林各龄级计盒维数通常也高于林线各龄级，表明不同海拔或者不同群落类型中的乔木树种具有不同的水平空间占据能力。林线区种群分布格局的计盒维数都很低，占据现实水平空间的程度较低，具有相对较高的生态间隙维，其潜在占据空间的能力较高，群落还可提供给种群的最大空间限度较大，但实际上由于受群落中种内、种间的竞争及林线区恶劣的生态环境条件的限制，其潜在空间占据能力可能难以表现出来。 青藏高原东缘高海拔地带以季节性游牧为主要的资源利用和生产方式，阳坡森林郁闭度低于阴坡，灌丛数量和种类较阴坡少，融雪早且积雪时间短，所以阳坡包括高山林线区成为当地牧民游牧路线的必经之地。牲畜的践踏、啃食使得幼龄乔木树种个体数量大大减少，严重阻碍了林线乔木种群的自然更新，同时种群占据空间的能力也明显降低。因此可以认为，在青藏高原东部地区，山地游牧等人为干扰叠加于恶劣的自然条件，阳坡林线的自然更新潜力受到抑制，其生存状态较之阴坡林线显著恶化，并可使阳坡林线高度逐渐降低。高山林线区森林一旦破坏在短时间内很难有效更新和恢复，因此，对于处于恶劣高山生境中的乔木种群应加强保护，同时适度控制人为干扰强度和幅度以减少其直接和间接破坏，防止阳坡林线退化并促进高山生态系统的自然恢复。 Eastern Qinghai-Tibetan Plateau has the highest timberline of the world. On the basis of field surveys and literature reviews, three typical alpine timberlines were chosen for in-depth studies, i.e., Baima Snow Mountain in northwest Yunnan, Zhegu Mountain and the waterhead area of Minjiang River in west Sichuan. Using the methodologis of population ecology, we analyzed the population structure, survival characteristics, spatial point patterns and fractal dimensions of the timberline tree populations and discussed the impacts of grazing on the structure and spatial pattern of alpine timberline. Compared with closed forests, the community structure of timberline is simpler, usually with one or two species constituting the tree layer. Differences also exist in the growth forms: the trees were significantly shorter with more stems and branches, reflecting morphological adaptation of trees to the severe conditions at timberline. In the eastern Qinghai-Tibetan Plateau, Abies spp. often formed alpine timberline in the north-facing slope while Sabina spp. and sometimes Picea spp. in the south- facing slope. The population structures of north-facing slope showed an increasing trend, with numerous seedlings and saplings. However, the survival curves tend to follow Deevy-III because of high dead ratio of young individuals. There are only few seedlings in the south-facing slope with heavy grazing, demonstrating that human disturbance may prevent regeneration at alpine timberline, which was confirmed by comparisons between fenced enclosures and control plots in the Kaka Valley. Depending on the spatial scales on consideration, the individuals of different age-classes showed clumping, random or even distribution, but mostly with clumping distribution. At all scales, individuals in different age-classes were all significantly correlated with each other while the seedlings were usually more correlated to two other age classes. This high degree of correlation among different age classes indicates that individuals of different age classes are spatially interlocked with each other, which helps sufficient utilization of various resources and is conducive to the survival and development of population. It is another adaptation strategy for trees at the severe environment. The spatial patterns of different age classes had different box dimension. In general, the box dimensions of total individuals and each age class at timberline are always smaller than that of closed forests, suggesting that space occupation capacity is not the same for populations at different altitude or in different communities. Populations on both the south- and the north-facing slopes had a very low box dimensions (far away from the max., 2), however, the lower the box dimension, the bigger the potential space provided by community. In fact, because of inner- and inter- competition as well as the severe conditions at timberline, this kind of potential ability can hardly be realized. Mountain pastoralism is the major type of as well as the only most effective way of resource uses in the high elevation regions of the eastern Qinghai-Tibetan Plateau. Due to lower canopy cover, less bushes and short snow-cover time, south-facing slopes became the favorite pastures. Damages from livestock through tramping, browsing and others have greatly reduced the number of young individuals. As a result, the potential of timberline trees to regenerate and their ability to occupy more space are greatly inhitibted. We conclude that human disturbances (mountain pastoralism) as well as harsh environmental conditions co-worked to inhibit the regeneration of tree populations in the south-facing slope and made south slopes more difficult than the north-facing slopes for trees to survive and develop, resulting a gradual retreat of timberline in the north-facing slopes. Forests at alpine timberline are susceptible to disturbance and difficult to regenerate and restore once damaged and controlling human disturbances is important for protecting the forest ecosystems at the timberline area.