松嫩平原农牧交错带农、牧子系统能量与能值分析

【作者】 朱丽；

【导师】 郭继勋；

【作者基本信息】 东北师范大学 ， 生态学， 2004， 硕士

【摘要】 松嫩平原地处北方农牧交错带东段，长期受到人类活动的干扰，使本来就十分脆弱的生态系统愈发不堪重负。连年的割草与不合理的放牧制度使得草地子系统定期或不定期地流失了大量的物质与能量，使草地发生退化演替；再加之农田子系统的广种薄收，资源利用率较低，使这一地区的生态系统受损，土地风蚀沙化、水土流失、盐碱化、干旱化加剧，生产力降低，造成对农牧业生产和人民生活的严重危害和生态环境的重大威胁。本论文针对以上现象，采用能量与能值分析相结合的方法，分别从群落水平、生态系统水平和区域水平多尺度衡量、探讨该地区不同土地利用方式下的农田子系统、割草地子系统以及放牧地子系统的能量格局和能流机制，定量分析环境资源与生产活动的真实价值以及它们之间的关系，寻找农业生态系统生产力低下、生态环境恶化的根本原因，并提出相应的解决方法。本论文的研究工作主要包括以下几个方面：1．在生物量和热值测定的基础上，研究了上述3个子系统中植物群落的能量净固定量和太阳能转化效率，利用分室模型对群落能量的流动进行了稳定性分析。3个子系统中的植物群落正处于能量积累状态，其能量净固定量与净积累量达到平衡态所需时间不同。群落净固定量较快，只需1年左右；群落净积累量因不同子系统生境条件而异，大约需7～13年，其中农田子系统最长，放牧子系统次之，割草地子系统最短，即系统所受干扰强度越大，其自我调节能力就越差。群落光合有效辐射转化率分别为农田2.35 %，割草地0.97%和放牧地0.46%。2．运用能值分析理论客观度量了3个子系统能值投入格局与能值产出情况，由此建立了能值指标体系，并结合能量分析指标，采用等量齐观法对3个子系统包括生态效益在内的综合效益进行了评价。结<WP=6>果表明：割草地子系统的综合效益最大，具有较强的发展潜力；增加该子系统的工业辅助能和高能值的科技投入，可以改善整个系统的生态环境，同时有利于带动农田子系统的稳定、持续发展。3．对松嫩平原农牧交错带中心区域的长岭县从1980年至2000年间农业生态系统的基本生态流进行了能值分析，通过计算得到一系列可反映环境和生产关系的能值指标年际演化动态，同时与其它相应系统进行比较，综合分析了长岭县自然环境基础资源利用状况，农业生产结构、特征及其可持续发展的演进态势，为制定该区生产政策和持续发展规划做了有益的探索。更多还原

【Abstract】 The Songnen grasslands dominated by Leymus chinensis provide fine pastures for grazing and hay production in the east of the north farming-pastoral zone of China. However, due to successive mowing and over-grazing, the grassland subsystem has experienced huge loss of matters and energy, causing ecosystem degradation successive. In addition, extensive cultivation in the farming subsystem makes resource use efficiency much lower. Both that has led to the damage of the ecosystem of the grassland and farming-pastoral zone. Land wind erosion and desertification, soil erosion, salinization and aridity are aggravated and the productivity is reducing. All of these greatly endanger the farming and animal husbandry production, and become the fatal threat of the environment.Aimed at the above-mentioned problems, the dissertation probed into the patterns and mechanisms of energy-emergy flows in the farming subsystem, the mowing subsystem and the grazing subsystem as case studies by means of multi-scale analyses including the community level, the ecosystem level and the region level. In order to find out the fundamental reasons of lower productivity and degenerated ecological environment, emergy based indices were applied to provide insights into the thermodynamic efficiency of the process, the quality of its output, and the interaction between the process and its surrounding environment. Then, focusing on its economic and ecologic load, the corresponding way out was also brought forward to insure long-term sustainability of the farming-pastoral ecosystem. Following are the main aspects in the studies：1. Based on measurements of biomass and calorific value, we studied energy fixation and conversion of the communities in three above-mentioned subsystems. The results of the stability analysis by means <WP=8>of compartment models were：The equilibrium state in the process of the energy flow was asymptotically stable, regulated by a negative feedback mechanism. The subsystems were in the state of energy accumulation. The time required for the net energy production and the net energy accumulation of the communities reaching the equilibrium state differed among the communities from different subsystems. The former needed about one year, whilst the latter varied from seven years to eleven years in the order the farming subsystem > the grazing subsystem> the mowing subsystem. The self-regulating abilities of the communities in the three subsystems were found to decline significantly with increasing intensity of human disturbances. For the available photosynthetic active radiation (PhAR), energy conversion efficiency (ECE) of the communities was 2.35% in the farming subsystem, 0.97% in the mowing subsystem, and 0.46% in the grazing subsystem.2. By means of emergy analysis, the inflows and outflows of energy and other resources evaluated on a common basis, i.e. the content of solar equivalent energy, were objectively measured in the case studies. Indices and ratios based on energy and emergy analyses were calculated and used to evaluate the behaviors of three subsystems. Their dependence upon the fractions of renewable and nonrenewable inputs as well as locally available versus purchased inputs from outside was stressed. The production of the subsystems that utilized natural resources rationally yet maintained ecological stability was necessary. Ecologically sound, yet productive, use of resources required indicators that assessed not only productive and economic factors, but also environmental impact and ecological effects. Thus, to study a production activity and its interaction with the environment, a new index system of synthetical evaluation, capable of considering ecological and economic aspects, was set up and applied to three subsystems to evaluate how sustainability. The results demonstrated <WP=9>that the mowing subsystem had the greatest synthetical benefits and potentialities of sustainable development. More inflows of industrial subsidiary emergy and high emergy-contained technology into the mowing subsystem shoul更多还原