长白落叶松人工林天然更新幼苗分布格局及其研究方法的比较

Spatial Distribution Pattern of Larix Olgensis Natural Regeneration Seedling in Larix Olgensis Plantation and Data-Mining of Seedling Spatial Mapped Points

长白落叶松是东北东部地区主要造林树种之一。该文研究了55 a生长白落叶松人工林天然更新幼苗的空间分布格局。测定了样地内(30 m×18 m)所有天然更新幼苗的坐标、地径和苗高。在幼苗坐标点图的基础上,进行了23个取样尺度(离散尺度)下的相邻格子法的空间格局分析:采用Poisson分布、负二项分布和正二项分布拟合幼苗的离散分布,方差均值比、Morisita指数和最近邻体法确定了空间分布格局,C_A指数、Green指数和负二项参数K值度量了它们的聚集强度。利用更新幼苗的坐标点图,采用地统计学中的半方差分析方法和空间点格局方法(采用Ripley二次分析法)研究了尺度连续变化条件下更新幼苗空间分布格局和聚集强度的变化并确定了其聚集规模,利用最近邻体法的计算方法分析了更新幼苗的自然定植特点。结果表明:1)更新幼苗所有离散尺度下(样方面积从1 m^2到18 m^2)均呈聚集分布。连续尺度下,在0-10.5 m的半径区间内呈聚集分布,在10.5-12.3 m的半径区间内呈随机分布。2)离散尺度下(样方面积从1m^2到18m^2),聚集强度随尺度的增加而增加。连续尺度下,在0-10.5 m的半径区间内,聚集强度随尺度的增加表现出先增加后降低的趋势,在半径(尺度)为4.2 m处聚集强度最大。3)此次调查的样地范围内天然更新幼苗呈现聚集状态生长的平均最大聚集斑块(聚集规模)的半径为4.79m。4)天然更新幼苗之间的平均距离为0.30-0.42 m,更新幼苗生长在与母树相距2.99-3.26 m之外的空间。5)相邻格子法(传统的样方方法)和空间点格局分析法对格局的判别和格局强度的确定基本一致,但是空间点格局分析法能够反映出尺度连续变化条件下格局和格局强度的变化。它与最近邻体法和地统计学方法等以种群分布的坐标点图为数据源的分布格局的研究方法的结合应用,能够探索出种群格局方面的大量信息。

Larch（Larix olgensis） was one of the mostly planted tree species in East-northeast China. In this paper, spatial distribution pattern of larch natural regeneration seedling in 55a larch plantation dominated by Larix olgensis was analyzed. The coordinate, basal diameter,and height of natural larch seedling in plot （30 m×18 m） were surveyed. Twenty-three kinds of contiguous grid quadrat sampling based on seedling spatial mapped points were simulated, and traditionally data-mining methods of spatial pattern were utilized to find spatial patterns at twenty-three kinds of discrete scale. Traditionally data-mining methods of spatial pattern in this paper included： utilizing discrete poisson, negative binomial and binomial distribution functions to fit seedling discrete distribution; variance to mean ratio, Morisita index and nearest neighbor analysis were used to confirm seedling pattern type; utilizing CA index, Green index and K value of negative binomial distribution to quantify pattern intensity. Semivariogram analysis and spatial point pattern analysis （Ripley＇s second order analysis method） based on seedling spatial mapped points were utilized to find the change of spatial pattern type and pattern intensity at continuous scale, and patch size. Seedling spatial arrangement by seedling nearest neighbor distance from seedling and from old-tree was studied to find larch natural regeneration inhabitancy character. Seedlings were clumped at all discrete scales （quadrat area, 1-18 m^2）. At 0-10.5m （radius range） continuous scale, seedling pattern was aggregate pattern, but at 10.5-12.3 m （radius range） continuous scale, seedling pattern was random pattern. At all discrete scales （quadrat area froml m^2 to 18 m^2）, aggregate intensity indexes increased with scale increasing. At 0-10.5 m （radius range） continuous scale, aggregate intensity first increased with scale increasing, and then declined at greater scales. At 4.2 m （radius） scale, aggregate intensity was the maximum. The biggest radius of patch, which was formed by natural regeneration seedling, was 4.79 m. The seedling nearest neighbor average distance between seedling and rom old-tree were 030-0.42 m and 2.99-3.26 m, respectively. The results from contiguous grid quadrat sampling method and spatial point pattern analysis method were very similar on the whole in their abilities to discriminate spatial pattern and quantify aggregate intensity, but spatial point pattern analysis method was superior in its ability to detect changes of spatial pattern and aggregate intensity with scale continuously changing. The combined utilization of spatial pattern methods based on spatial mapped points, such as spatial point pattern analysis, nearest neighbor analysis and semivariogram analysis, would provide abundant information about population pattern.