基于数字信息模型的城市湿地公园生态分析与评价

为增强城市湿地公园生态分析与评价体系的准确性和科学性,以白鹭湾湿地公园为研究对象,运用卫星影像解译、采样点预选、调查记录等方法,现场采集获取了大量数据及模型,通过综合信息平台整合形成公园地表信息模型、专题分析模型、叠加评价模型、各项专题图、生态评价报告、数据统计等现阶段重要信息。在定性、定量、定位研究基础上,对地理高程、坡向、坡度、汇水通道、湿地及水域、动物主要活动分布、湿地植物分布、景点分布、建筑与人工设施分布等具体因子进行量化评价及特征总结,并进行综合因子叠加分析,提出量化模型参考,有针对性地提出公园生态建设与管理建议。     

活立木市场交易价格影响因素研究

基于2018—2020年浙江省龙泉市900宗活立木交易数据,采用半对数多元线性回归模型研究木材市场价格、单位面积蓄积、林分质量等因素对活立木交易价格的影响。结果表明,龙泉市活立木交易平均价格为3 976元/hm²,木材市场价格、单位面积蓄积、单位面积株数、平均胸径对活立木交易价格有显著的正向影响;流入方性质和流出方性质对活立木交易价格有显著影响,且影响存在差异性。提出规范木材市场交易,加强森林资源评估工作,提升交易的公平性,全面推进林权抵押贷款等建议。     

天河公园“拆围透绿”工程边界空间绿化模式研究

边界空间绿化是开放性城市公园的重要因素,是衔接公园与城市绿地系统的重要措施。以广州天河公园“拆围透绿”工程为例,分析边界空间绿化存在通透性不足、与城市融合度不高、地域文化缺失、绿地管理不到位等问题,采用“保留、清杂、复绿”景观策略,确定点状、带状、片状景观3种绿化模式,制定“护栏+绿化”、绿化组团、“微地形+绿化组团”3种空间分隔手法,并从复绿植物种类选择、通透植物空间结构、活化林下消极空间、柔化公园边界空间、强化城市地域文化、加强空间绿化管理6个方面进行绿化提升,优化了公园的生态环境和开放性。     

生态产品资源富集山区人民贫困成因、扶贫模式与脱贫攻坚成果巩固路径

以浙江丽水为例,从生态产品价值实现的角度分析生态产品资源富集山区人民贫困的成因以及主要采用的扶贫模式。分析认为,生态农业扶贫模式最具优势,并通过该模式取得了显著成效,获得了国家领导人的认可。进一步分析了巩固脱贫攻坚成果与乡村振兴战略衔接的必要性,在此基础上提出了巩固生态产品资源富集山区脱贫攻坚成果的路径,一是加大生态保护力度,让良好生态产品资源优势成为丽水生态产品资源富集山区生态产业发展的基础和保障,二是增进山区人民自我发展能力,促进生态产业发展,三是破解生态产品资源开发利用人才缺乏的困境,四是完善生态产品资源富集山区的基础设施,五是有效衔接政府行为和企业力量,协同推进脱贫攻坚成果巩固。     

Why is the productivity of Douglas-fir higher in New Zealand than in its native range in the Pacific Northwest,USA?

Douglas-fir (Pseudotusga menziesii (Mirb.) Franco), a native to the Pacific Coast Range in North America, is recognized as a tree that is long-lived and can grow rapidly to standing volumes that approach the highest recorded for temperate conifers. Managed plantations in western Oregon register maximum periodic annual increments (PAI) at ages between 20 and 40 years of ∼30 m³ ha⁻¹ year⁻¹. The same seed source, when planted in New Zealand and elsewhere in the Southern Hemisphere, may attain a PAI of ∼50 m³ ha⁻¹ year⁻¹. Is this higher productivity mainly related to climate or to isolation from native pests? To evaluate the role of climate, we obtained meteorological data from plantation sites in New Zealand and Oregon, from which we established relationships between mean monthly temperature extremes and solar irradiance, air humidity deficits, and frost frequency. Using these empirical relationships, long-term weather records were converted to the meteorological variables required to drive a process-based forest growth model, 3-PG, for sites approaching the most productive in New Zealand and in Oregon. Annual precipitation is similar in both areas, but sites in Oregon receive only 10% during the growing season, resulting in humidity deficits 30% larger than those recorded in New Zealand. According to sensitivity analyses and direct measurements, the more productive Douglas-fir forests in Oregon avoid the limiting effects of summer drought by obtaining water from the subsoil and fractured bedrock. If such forests were under a reduced evaporative demand similar to that in New Zealand, we show that they would exhibit comparable productivity.     

Effects of changes in land use and land cover on sediment discharge of runoff in a typical watershed in the hill and gully loess region of northwest China

Land use plays a much more important role than other factors, such as climate, soil properties, topographic features, vegetation coverage, human activities and others, in affecting soil erosion and sediment discharge. In order to understand the effects of changes in land use on sediment discharge and to provide a theoretical basis for land use planning, management and ecological restoration, we used the controlled Qiaozidong watershed and the uncontrolled Qiaozixi watershed in the third sub-region of the Loess Plateau as examples and analyzed the effects of land use and land cover on the discharge of sediments. The results show that the impact of land use and land cover on the annual amount of sediment discharge is significant. Compared with the uncontrolled watershed during similar periods, the amount of sediment discharged from the controlled watershed was reduced by 44%, 75% and 86%, respectively, in wet, normal and dry years. In the controlled watershed, compared with the period from 1986 to 1994, the amount of sediments discharged was less during the period from 1995 to 2004. The impact of land use and land cover on sediment discharge demonstrated characteristics of seasonal fluctuation. The effects of sediment reduction in the controlled watershed were greater than those in the uncontrolled watershed in May and September. In the controlled watershed, the reduction effect coincided with the distribution of rainfall. The amount of discharged flood sediments is closely correlated with rainfall, rainfall intensity in a 60 min period and the volume of flood. The rainstorm-runoff process and the rainstorm-sediment discharge process demonstrate that land cover has a strong regulatory and control function in the flood process and sediment discharge in rainstorms. For the controlled watershed, given the same precipitation frequency distribution, the average amount of sediment discharged during the land use period from 1995 to 2004 was less than that during the earlier land use period from 1986 to 1994 under every recurrent period. __________ Translated from Journal of Beijing Forestry University, 2007, 29(6): 115–122 [译自: 北京林业大学学报]     

Growth-Oriented Logging (GOL): A new concept towards sustainable forest management in Central Amazonian várzea floodplains

Against a background of increasing human populations in developing countries, and global climate change, conservation of tropical forests remains one of the most important ecological challenges of our time. One of the biggest difficulties for ecologically sustainable management of tropical forests is obtaining reliable growth data for trees, which is a prerequisite for determining harvesting volumes and cutting cycles. GOL is the first concept for sustainable management of tropical timber resources in Amazonian floodplain forests (várzea) based on species-specific management criteria, such as minimum logging diameters (MLDs) and cutting cycles. From timber species with varying wood densities of different successional stages, volume stocks have been estimated in 1-ha plots and 12 growth models have been developed based on tree rings, which are annually formed as a consequence of the regular, long-term flooding. The MLDs of timber species vary between 47 and 70 cm and the estimated cutting cycles differ the 10-fold, from 3 to 32 years. These enormous differences in the growth rates between tropical timber species are not considered in current management practices, which apply only one diameter cutting limit and one cutting cycle to harvest many tree species. This practice risks the overexploitation of slow-growing timber species, while the fast-growing timber species with low wood densities cannot be efficiently used. Based on the timber stocks and lifetime growth rates, the GOL concept has been created as an aid to improve forest management in the Central Amazonian várzea. The model is unique for tropical silviculture.     

国外森林生态系统管理模式的经验与启示

介绍了美国、加拿大和德国3个国家森林生态系统管理模式的基本情况及其相应的社会、经济和文化发展背景, 分析比较了它们的基本特征, 并在此基础上讨论对我国开展森林生态系统管理的几点启示。     

资源约束条件下工期、质量、成本综合均衡优化

工期、质量、成本称为工程项目的三大控制目标,三者相互依存,相互影响.工程项目优化控制的理想结果是同时实现合理的工期、较低的费用和较高的质量.利用多属性效用函数以及效用分解定理,建立了基于资源约束条件下的工期、质量、成本的综合均衡优化与控制模型,并引入遗传算法,对模型进行求解.通过一个应用实例,对实际施工中的工期、质量、成本综合均衡优化给出了备选方案.     

基于生长规律与图像相结合的树木叶片动态模拟

虚拟树木生长是虚拟植物的一个研究方向,主要研究建立能体现其内在生理特征的生理生态模型和外在表现的可视化模型,是植物学家进行研究的重要工具.