| Forests are the carder of forest ecological benefits. The spatial distribution of forests determines that of forest ecological benefits. By the means of GIS(geographic information system), which provides powerful support for analyses of the distribution of forest ecological benefits, accurately quantifying the forest ecological benefits in terms of both forest products and financial income, analyzing the distribution of ecological benefits, and providing visual results and statistics provide valuable will greatly help forest managers in decision-making.This study constructed a theoretical and technical framework for generalized spatial analysis of forest ecological benefits. The research was based upon previous studies and borrowed the strength of GIS in spatial analysis.Because ecological benefits model developed in this study is a model system, consisting a number of individual models, simultaneously fitting compares favorably with fitting separately. Seemingly unrelated regression(SUR) is a special case of simultaneous equation system (SES). The SES used in this study features 1)it supports non-linear models; 2) multiple estimation methods are available, e. g., FIML(full information maximum likelihood), 3SLS (three steps least squares); 3) it can be estimated with SAS(Statistical Analysis System), which is the universally accepted statistical package in the world.This study discussed identification of SUR and SES, and proposed estimation methods for model system that is idenfiable or over-identifiable, such as two-step least squares(2SLS), indirect least squares(ILS), and Three-step least squares(2SLS). An SES model system of forest benefits was developed based up the data obtained from observations of national ecological research stations from 1999 to 2000. Parameter estimates by 2SLS, 3SLS, and ILS and comparisons were given. An SAS script file was attached either. It is believed that the estimation methods used in this study and the corresponding script can simplify complicated computation of SES and SUE, and will help research works in this area.A linear spatial analysis system of forest ecological benefits(FLMSA) was developed by customizing a COM component of GIS, Mapobjects and using Visual Basic. FLMSA supports a variety of image file formats such as Shapefile,CAD,Coverage, and SDE. It has common functions of GIS, and moreover, it can automatically track and obtain coordinators of points, lines, gravity centers of image plane, and slopes. The system also can convert longitude and latitude coordinators to grid coordinators, and vice versa. It can use data from forest inventory permanent plot and subcompartments to calculate 13 ecological benefits in terms of forest product and financial income. FLMSA can produce visual distribution chart. It can be expected that the system, as specialized software for forest ecological benefits, will have extensive applications in this area.Based upon data of 4 forest management inventories(spanning 30 years) obtained from Jiaohe experimental forests of Beihua University, it was found that ecological benefits in the underlying area was decreasing.The forest ecological benefits were 94, 670, 000 RMB/ha in 1967, whereas they were 86, 740, 000 RMB /ha in 2002, decreased by 8.37ï¼…. The decrease is not very significant due to good maintenance of forest in the area.Based upon the forest carbon storage model used in this study, it was found that carbon storages increased from 2358004 tons of 1994 to 2443035 tons of 2002, 85031 tons more sequestrated. During this period, cutting and thinning resulted in an amount of 253707m~3 volume loss, while the carbon storage was 158785 tons increase, calculated according to forest type. In other words, the total carbon sequestration was 243816 tons during the past 8 years, and annual carbon sequestrated by forestlands was about 1.10 t/(hm~2.a).According to data of 1567 forest inventory permanent plots, it was found that the forest ecological benefits of forests in Heilongjiang was about 19.3128919 billion RMB/ha, and the carbon storage in this area is 0.44158 billion tons, which is equivalent to 56.067 billion RMB. Among the 12 forest ecological benefits, water conservation, carbon sequestration, air purification, and soil conservation play dominant role, taking up a proportion over 88.5ï¼…. The study indicated forest benefits in term of financial income are between 1500 and 3000RMB/ha.It was shown by the study that GIS spatial analysis, combined with evaluation of forest ecological benefits, has promising applications. FLMSA and the frame of generalized forest benefits analysis provide a powerful means for quantifying carbon storage trade, forest ecological engineering benefits, and compensation of forest ecological benefits. FLMSA is compatible with a variety of data file formats, and easy to maintain. Using forest inventory data can also use it for forest ecological benefits in a smaller scale. Therefore, it is believed that it can be used as a tool for further studies. |
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