【作者】 花利忠；

【导师】 江希钿；

【作者基本信息】 福建农林大学 ， 森林经理学， 2004， 硕士

【摘要】 用森林生长模型科学高效地指导林业生产一直是林业经营者采用的主要方式，但这些模型大部分是经验模型。随着林业生产集约化的提高，随着植物生理生态学、计算机技术等学科的飞速发展，随着人类对环境意识的日益增强，森林生长和收获的机理模型越来越受到森林研究和森林资源管理者的重视。 本文介绍了3PG模型，这是一个同时结合了天气、立地、经营水平和树种来预测林分生产力的基于生理过程的林分生长模型，它已广泛应用于世界上许多国家和地区。 模型用一系列方程动态模拟太阳辐射的逐级递减及碳量守衡和水量平衡来模拟林分系统和外界环境每月的动态变化。用Beer—Lambert日光消减规律来模拟林分冠层吸收的光合有效辐射：受养分、土壤含水量、林龄、水汽压差、土壤盐度、霜冻和温度等限制因子的共同影响，只有少量光合有效辐射用于树木的光合作用，这部分光合有效辐射按一定的量子效率同化CO₂合成有机物质；林分冠层所固定的碳按碳量守衡和一定比例分配给树叶、树干和树根；树干所吸收的碳量转化为木材产量，进一步来计算材积、树高和胸径。同时模型根据土壤水贮量变化来模拟月森林水量平衡，它详细模拟了大气降水，地下水、人工灌溉、林分蒸腾量、渗透水量和土壤水之间的动态变化。 对广东省西部的雷州半岛上的三种商业桉树人工林：尾叶桉、ABLw5和CloneU6进行了长期的林分树高、胸径和生物量的测量，土壤含水量、水分利用的观测和地下水位、土壤性质的调查，这些数据都用来估计和校正模型参数。同时在林地建立了自动气象观测系统对桉树人工林主要气象因子进行定位观测，包括太阳辐射、降雨量、风速、最高温度、最低温度和相对湿度。 通过分析比较林分材积、胸径、树高、叶量、干量、叶面积和水分利用的观测值与模型值，表明：3PG模型是预测桉树人工林生产力的一种有效工具，其模拟精度和可靠性是令人满意的，它的应用将为林业经营者制定合理的营林、抚育管理和采伐决策方案提供可靠全面的科学依据：尾叶桉的最佳轮伐期为7a，而ABLw5和CloneU6为6a：该地区年总蒸腾量不足600mm，远远低于这一地区的降雨量，证明“桉树是抽水机，消耗过多地下水”的说法是没有道理的。同时本文还模拟了桉树人工林的直径分布，预测了它们10a内的生长量并绘制了整个雷州半岛桉树林分第5a材积分布图。随着3PG模型的不断发展，并结合其它模型（如地理信息系统），它必将发挥越来越重要的作用。更多还原

【Abstract】 It’s used to be mainly management means for forest managers to scientifically, effectively plan and manage forest production by forest growth and yield models, but most among these are empirical models instead of mechanistic models or processed models. With the great improvement of forest production intensivism and increasing attention of environmental protection, processed-based forest growth models can be more and more attached importance to by forest researchers and its resource managers, as a great number of subjects such as physiological plant ecology, computers agrology, meteorology, etc, make an immense progress.3PG model is introduced on the papers, which can predict stand productivity with combinations of climate, site condition, management and species and is widely applied as a planning tool by forest managers in many countries and regions throughout the world. It uses a series of equations to simulate the carbon balance, water balance and diminishing solar radiation in order to simulate dynamically monthly change of forest and its environment. The model calculates total carbon fixed from canopy quantum efficiency and utilizable, absorbed photosynthetically active radiation, obtained by correcting photosynthetically active radiation by a forest canopy, simulated by Beer-Lambert law relating the absorption of light, for the effects of temperature, nutrition, atmospheric vapor press deficit, stand age and soil water availability. The carbon fixed by forest canopy is partitioned into leaves, stems and roots respectively as to some allocation proportions. At the end, the volume is got from amount of carbon in stems. At the same time, in view of the change of soil water storage, it simulates dynamitic change among atmospheric rainfall, groundwater, irrigation, forest transpiration, deep drainage and soil water.Measure of tree and stand growth, biomass relationships , soil available water content and its depth , groundwater depth and water use from plantations on the Leizhou Peninsula of western Guangdong province have used to estimate model parameters values for major commercial eucalyptus genotypes: E.urophylla, ABLw5, and CloneU6. Climate data for modeling may be satisfactorily estimated from routine daily meteorological observation including temperature, rainfall, and solar radiation etc.The comparison between modeled and observed values of stand volume, DBH, height, LAI, leaf weight, stem weight of above three Eucalyptus plantations and water use of E.Europhylla showed that 3PG model is a convenient and efficient means of predicting the productivity of Eucalyptus plantations with the satisfactory accuracy and reliability of modeled predictions and could provide a successful and versatile basis for decisions on stand establishment, tending and harvesting for forest managers in relation to planting location, climate, soil conditions and forest management; it’s advisable to make 7-year rotation for Urophylla and 6 year for other species; the total yearly transpiration with not more than 600 mm that is far less than rainfall in the area ,which proves that the opinion of Eucalyptus plantaions depleting too much groundwater can’t hold water. At the same time, growth of Eculyptus plantations in 10 years, their weibull diameter distributions can be predicted and volume distribution map in the whole Leizhou Peninsula can be demonstrated. As the development of the model, it will play more and more important role in the future if it can be integrated into other systems like GIS.更多还原