吉林省土地沙化趋势的初步研究

吉林省西部地区,由于所处地理位置和气候特征,形成大量风沙土,春季多风季节,风沙危害,严重影响春耕播种。长期以来,我省投入了大量人力、物力和财力,采取措施,防风固沙,为检验数十年防风固沙的实际效果,我们利用不同时期(1959年和1978年)航片,调查研究沙土动态状况,即是否进一步产生沙化,以期为吉林省农业环境规划及建设打下良好基础。     

轿子山飞播示范草场发展现状及对策

针对轿子山飞播示范草场的植被与开发利用现状进行调查研究,通过对轿子山草场进行实地踏勘和测量,对播区内与周边农户进行走访、座谈,对参与飞播和飞播后从事过该草场承包经营、科研、补植补种、复垦、管护的相关人员进行了解,在查阅大量档案资料的基础上,指出了轿子山飞播示范草场成功建设的借鉴意义,以及草场在管理利用中存在的问题,并提出了相应的开发利用建议,旨在为轿子山草场及同类型草场的合理开发利用提供科学依据。     

森林航空消防的应急预案建设的必要性及原则

森林航空消防是森林防火工作的重要组成部分,因具有反应速度快、机动性强、灵活性高、统观全局的优势,成为现代森林防火工作的发展方向和必然选择。国务院最新颁布的《国家处置森林火灾预案》中首次将森林航空消防列入国家预案中。本文结合国家预案,对森林航空消防预案建设的必要性进行论述,根据森林航空消防预案建设的目标,对其建设原则进行设计,为森林航空消防应急预案的理论建设和架构设计奠定基础。     

Effects of topography and management history on natural forest recovery in abandoned forest after clear-cutting in Miyazaki, Japan

We investigated factors limiting the recovery of natural forest in former large-scale conifer plantations abandoned after clear-cutting in southwestern Japan. We analyzed forest recovery status (“recovered” sites covered by evergreen broad-leaved trees, and “unrecovered” sites covered by pioneer community or nonvegetated sites) using aerial photographs and field survey. We applied logistic regression analyses to evaluate the effects of topography, construction of harvesting roads, distance from remnant forest, stand condition before clear-cutting, and prior land-use history on forest recovery. Human factors, i.e., land use and clear-cutting age, were found to affect to forest recovery more than environmental factors such as topography. Harvesting roads had the strongest negative impact on forest recovery. Forest recovery after clear-cutting of young sugi plantations also took longer than after clear-cutting of old sugi plantations or evergreen broad-leaved forests. Furthermore, areas formerly utilized as meadows recovered less successfully than those that had been managed as coppices. The influences of these factors were thought to be promoted by the advance reproduction as the regeneration sources for forest recovery. The influence of stand age before logging suggested an effect of thinning, which might alter the abundance of advanced reproduction in the understory. However, distance from remnant forest appeared to be less important. An influence of topography was also detected, but this could be partly explained by the existence of advance reproduction in the understory in certain topographic positions. Thus, our analysis suggests that regeneration sources originating from advanced reproduction in plantations play a significant role for the recovery of natural forest after clear-cutting.     

飞播用花棒种子丸粒化研究

针对飞播用种子丸粒化技术的不足,通过对各种原料配比对崩解时间的影响研究,使得处理后的丸粒化种子重量增加到原来的4～6倍,有效解决了种子"穿棉衣"与发芽和破损的矛盾.     

An approach to clarifying public preferences about silvicultural systems: A case study concerning group selection and clear‐cutting

To avoid large clear‐cut areas in recreation areas, three experiments where group selection was used to transform even‐aged stands of Norway spruce (Picea abies (L.) Karst.) into uneven‐aged stands were started. Two of these group selection stands were compared with adjacent forests managed by the clear‐cut system on the basis of the opinion of seven voluntary groups. The respondents have given their judgement of the forest sites in a semantic differential test. All parties made assessments when visiting the forest sites. In addition, two of the groups made assessments of black and white photographs representing the forest sites. The methods used were found to be both reliable and valid. A very low correlation was obtained between the assessment of whole forest areas and the mean value of the assessments of the stands within the same area. According to this study, the group selection method is preferable to clear‐cutting in even‐aged stands of Norway spruce if the attitudes of the voluntary groups are to be met.     

A pre-harvest method for predicting understory light levels created by artificial canopy gaps

A new method for predicting understory light levels around an artificial canopy gap prior to the selective cutting is presented. In two even-aged coppice stands, hemispherical photographs were taken at a height of 1.3 m, and crowns of each canopy stem on the photographs were identified by field observations. To predict light levels after cutting, we used computerized images of the hemispherical photographs, in which we digitally erased all crowns to be cut (named ‘erasing method’). Light levels were calculated by an analyzing program; HEMIPHOT. Light levels predicted by the ‘erasing method’ were compared with that calculated by the ordinary photograph-analyzing method using photographs taken after the actual cutting. The correlations between the two methods were highly significant in the two stands. The ‘erasing method’ is eminently effective for the prediction of understory light levels in an artificial canopy gap.     

环鄱阳湖越冬水禽航空调查

采用航空调查的方法对鄱阳湖区的越冬水禽进行种类、数量和分布情况的调查,快速准确地取得了有关珍稀越冬水禽的分布情况和栖息地现状,为整个鄱阳湖区越冬水禽的保护提供了科学依据。     

1999年春鄱阳湖鹤类和大型水禽航空调查报告

通过调查,基本查清鹤类和大型水禽在鄱阳湖的越冬分布状况及栖息地生境特征。     

探讨利用航空象片信息估测小班调查因子的方法

利用航空象片信息提取小班调查因子。首先利用航片对每个小班的林分类型、龄组、郁闭度和最大冠幅进行判读;其次根据以往的资料,建立林木株数分布,每公顷株数预测,直径与最大冠幅及胸径与树高、年龄等相关模型;最后由判读因子和上述模型借助于计算机求出林分蓄积量、断面积、各径阶株数,平均直径、平均高、平均年龄等因子。该试验是在我国北方次生林区进行的,多数小班因子可由航片提取,蓄积量估测的精度达到85％以上,可提高工作效率1—2倍。为我国二类森林调查提出了一种新的方法。