瑞典国家森林资源清查的经验与借鉴

瑞典国家森林资源清查体系历经 80年的建设历程 ,积累了丰富经验。收集近期瑞典有关国家森林资源清查的资料 ,按基本发展情况、抽样方案设计、调查因子设计、数据统计分析、调查工作组织等方面编译整理 ,以便我们在新的一次全国森林资源清查工作中学习和借鉴     

Development of utility and location indices for classifying agroforestry species: the case of Rwanda

In a study of farmer knowledge and experimentation of trees and tree cultivation, two categories of farmer consultants were identified, tree experts (n = 44) and control farmers (n = 70), via a two stage process of knowledge ranking and community interviews conducted in three communes in southern Rwanda in 1992. A detailed inventory of tree species was conducted revealing two key characteristics for on-farm trees: multiple utility and high locational flexibility. In order to logically organize the species inventory, two indices, a utility index (UI) and a locational flexibility index (LFI), were developed. The two indices were calculated for each species and then plotted as the axes on a bivariate grid. While few species had both high utility and flexibility indices, the majority that did were indigenous species long used in agroforestry systems (e.g., Euphorbia tirucalli, Vernonia amygdalina, Erythrina abyssinica, etc.). A few naturalized exotics introduced in the 1930s (e.g., Grevillea robusta, Eucalyptus camaldulensis, E. saligna, E. maideni, Cupressus lusitanica and Persea gratissima) were also appreciated for their multiple utility and locational flexibility. Farm sizes varied, averaging 1.27 ha among tree experts and 0.18 ha in the control group. The mean number of species cultivated was significantly higher on tree expert farms (P < 0.01). However, tree density was much lower on tree expert farms (731 trees · ha^–1) than on control farms (1,689 trees · ha^–1). Competitive species were found primarily on larger farms, whereas smaller farms were associated with species of greater UI and LFI. Farmers demonstrated deliberate and rational choices about which trees to plant in accordance with each species utility and flexibility in relation to land availability.     

Strategic Decision for Random Inventory System Based on Mente Carlo''s Simulation Technology

Numerical simulation for random inventory system applying Mente Carlo's simulation technology is carried on,moreover system decision is made and optimal solution is arrived after research on relevant sensitive parameter.These results of research confirm that the way of making decision is practicable.Two important conclusions are proved by the data from an example inventory system.One of them is that optimal inventory strategic permit a restrictive short-of-stock policy in the case of paying for decrease because of short-of-stock;the other is that it embodies the ideas of zero-inventory technology and Just-In-Time(JIT).     

A Study on Artificial Neural Networks-based Medical Equipment Demand Forecast

In order to uncover the complex relation in the inventory data and lower the inventory level, based on the idea of black box method, all factors that influence demand are identified firstly. Then an initial forecast model of BP neural networks that adopt LM algorithm is established, and is trained using hospital inventory's history data. The interrelation's information of each factor that influences demand is stored in the link weights matrix W dispersedly. The final forecast model is obtained. We use the model to forecast the demand of medical equipment in Daping hospital. Based on it, the inventory cost is reduced enormously. The theory for the inventory system can be used to make management decision.     

新疆森林资源档案管理工作的探讨

介绍了国内森林资源档案管理研究现状,阐述了新疆自治区森林资源档案管理的基本情况,指出了新疆森林资源档案管理存在的问题,同时,针对其存在的问题,对今后工作的开展提出了对策建议。     

Estimating forest characteristics in scanned aerial photographs with respect to requirements for economic forest management planning

The objective of forest management planning is often expressed as maximum sustainable economic yield. Methods used to collect information for forestry planning should, therefore, include variables significant for economic evaluations of management alternatives. It is important to be able to differentiate mature stands with respect to timber volumes and species mixture. In this study, digital high‐altitude aerial photographs are tested as a data source for planning. Circular plot data from a forest estate in northern Sweden were used as reference material. Global positioning system (GPS) measurements, with differential correction, were used to georeference the plots. Harvesting priorities were calculated for each plot using the Forest Management Planning Package. Volumes, species mixture and harvest priorities were estimated using regression analysis based on textural and spectral information from aerial photographs. The results show that the dependent variables could be estimated fairly well using only spectral information, e.g., R ² = 0.44 when estimating timber volume at reference plot (10 m radius) level. Aggregated to stand level, the precision was comparable with customary field survey methods (e.g., RMSE= 13.4% for timber volume).     

Combining harvest sample data with inventory data to estimate forest biomass

Forest biomass databases which go beyond stem volume are needed for carbon balance calculations and also for forest monitoring, forest damage inventories and the solution of other related problems. In this article, it is shown how recursive multiple regression analysis can combine forest inventory data with biomass harvest data. The stand‐level conversion factor derived for Pinus sylvestris L. branch biomass for the “Severka”; Forest Farm shows a reasonable goodness of fit, with a coefficient of determination of R² = 0.87. Statistically significant coefficients were achieved by including stand density and the quadratic mean diameter in the regression. Equations developed for Switzerland, using Burger's Picea abies (L.) Karst. branch and needle conversion factors for individual trees, show R² = 0.87 and R ² = 0.91, achieved by taking h _dom.50, elevation, diameter at breast height and age into account.     

On the Field Performance of Transect Relascope Sampling for Assessing Downed Coarse Woody Debris

Abstract

Transect relascope sampling is a recently proposed method for making efficient inventories of coarse woody debris on the ground. However, before the method can be recommended, its performance in the field requires investigation. This paper presents the results of a field study in which 11 surveyors tested the method in two coniferous stands in northern Sweden. The average bias introduced by the surveyors was moderate under normal sighting conditions, but underestimation was substantial when combining a small relascope angle with poor sighting conditions. In all cases, the differences between the systematic errors of individual surveyors were substantial. The conclusion is that transect relascope sampling is not an appropriate method when the demand for unbiased estimates is high, e.g. in connection with long-term monitoring, but that the method can be useful as a first phase in double sampling or in ocular-based inventories aimed at identifying biologically valuable areas.     

浅析我国森林资源清查体系存在的问题与对策

全国森林资源清查是通过定期、准确查清各省的森林资源数量、质量及其消长动态,从而掌握森林生态系统的现状和变化趋势,对森林资源与生态状况进行综合评价。由于清查覆盖面积大、跨度时间长,清查结果不能有效及时利用。本文浅析了我国森林资源连续清查体系在应用中存在的不足,并提出改进措施,以期为完善我国森林资源连续清查体系提供参考。     

Assessment of N2O, NOx and NH3 emissions from a typical rural catchment in Eastern China

To evaluate the atmospheric load of reactive gaseous nitrogen in the fast-developing Eastern China region, we compiled inventories of nitrous oxide (N₂O), nitrogen oxide (NO_x) and ammonia (NH₃) emissions from a typical rural catchment in Jiangsu province, China, situated at the lower reach of the Yangtze River. We considered emissions from synthetic N fertilizer, human and livestock excreta, decomposition of crop residue returned to cropland and residue burning, soil background and household energy consumption. The results showed that, for the 45.5 km² catchment, the annual reactive gaseous emission was 279 ton N, of which 7% was N₂O, 16% was NO_x and 77% was NH₃. Synthetic N fertilizer application was the dominant source of N₂O and NH₃ emissions and crop residue burning was the dominant source of NO_x emission. Sixty-seven percent of the total reactive gaseous N was emitted from croplands, but on a per unit area basis, NO_x and NH₃ emissions in residential areas were higher than in croplands, probably as a result of household crop residue burning and extensive human and livestock excreta management systems. Emission per capita was estimated to be 18.2 kg N year⁻¹ in the rural catchment, and emission per unit area was 56.9 kg N ha⁻¹year⁻¹ for NH₃ + NO_x, which supports the observed high atmospheric N deposition in the catchment. Apparently, efficient use of N fertilizer and biological utilization of crop straw are important measures to reduce reactive gases emissions in this rural catchment.