我国落叶松林生产力的空间变化特征

落叶松林在我国有着广泛的分布。其空间差异也比较大。采用地统计学方法对我国落叶松林生产力的空间特征进行了分析。结果表明。落叶松种群和群落地理替代作用明显；落叶松林生产力空间异质性较大。其变化与空间尺度密切相关；地理位置、海拔高度等是影响落叶松林生产力的重要因素；在天然落叶松林的管理和保护以及人工落叶松林的发展上应考虑其空间特征。

The Characteristics of Spatial Variation of Larix Forests in Mainland of China

The Larix forests are widely distributed in mountainous areas in China. There are more than ten species in Larix genus which can form forest communities as constructive species or dominant species, such as Larix gemelini, L. sibirica, L. olgensis var. changpaiensis, L. principis-rupprechtii, L. chinensis, L. griffithiana, L. potaninii var. macrocarpa, L. potaninii, L. mastersiana, L. himalaica, L. speciosa etc. The spatial distribution map of Larix forests in mainland of China is displayed in this paper. The spatial heterogeneity of Larix forests is obvious from the analyses. The geostatistical methods, such as autocorrelation index, semivariance analysis, fractal dimension etc. were applied to study the spatial variations of productivity of Larix forests in China in this study. The results show that the species and communities of Larix have a special series of spatial succession, which is closely related to the variation of geographical variables. The productivity heterogeneity of Larix forests is great and is correlated with spatial scale, i.e. the spatial autocorrelations being positive in small scale, negative in mid-scale, and with great variation in large-scale. The semivariance tends to increase with increasing of spatial scales. There are many factors affecting the spatial characteristics of Larix forests, among which the geographical position, elevation etc. are the main factors affecting productivity of Larix forests. The productivity of Larix forests is negatively correlated with the longitude and latitude, which is due to that the change of these two factors strongly influence the quantity of heating and water conditions. The productivity of Larix forest is positively related with elevation, for elevation is tending to increase from the northeast to the southwest of mainland, along this gradient the natural conditions being improved greatly. The biomass of Larix forests is closely related to the age of forests. The biomass and the primary net productivity of Larix forests are both positively correlated with the indices of leave areas. This is identical to the general hypothesis. The biomass and primary net productivity are both effective indices in the study of spatial characteristics of Larix forests, however the primary net productivity is comparatively better because it is independent of forest age. The spatial characteristics should be considered in the management and protection of native Larix forests and the development of artificial Larix forests. The selection and combination of Larix tree species in plantation, for example, are dependent on spatial scales, i.e. systematic closed species should be combined in small scale, the series species of geographical succession should be considered in mid- and large-scale, and the widely distributed and adapted species should be applied in large- and great large-scales. All the three geostatistical mehods used in this study are effective in describing spatial characteristics of forests. They all have their own features and ecological meanings. The combination of them in similar researches should be suggested.