Comparison of Methods to Estimate Reineke's Maximum Size-Density Relationship Species Boundary Line Slope
Comparison of Methods to Estimate Reineke's Maximum Size-Density Relationship Species Boundary Line Slope
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DOI：
10.1093/forestscience/53.3.435
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发表时间：
2007-06
期刊：
影响因子：
1.4
通讯作者：
C. VanderSchaaf;H. Burkhart
中科院分区：
文献类型：
--
作者：
C. VanderSchaaf;H. Burkhart
最大径-密度关系（MSDR）为自然资源管理者提供了关于树木密度和平均树径之间关系的有用信息。获得一个有效的估计如何最大的树密度的变化与平均树大小的变化是必要的，以准确地描述这些生物学关系。本文探讨了三种方法来估计斜率（B）的MSDR物种边界线的种植密度范围内：普通最小二乘法（OLS），第一差分模型，和线性混合效应模型。在本文中，稳定性是指当拟合数据集中的种植密度范围发生变化时，参数估计值不发生变化的程度。当使用种植密度试验（种植密度范围为每公顷6，727至747株幼苗）的数据时，混合效应模型产生了最稳定的B估计值，而OLS产生了最不稳定的估计值。MSDR边界被定义为（1）描述单个林分边界的边界（MSDR动态间伐线）或（2）描述特定地理区域内特定物种在所有地点共有的MSDR（MSDR物种边界线）。通过定义两条MSDR物质边界线（在此标记为I和II），提出了对MSDR物质边界线的进一步细化。虽然两个MSDR物种边界线都位于所有观测值上方，但一个MSDR物种边界线II的斜率可以被认为是所有MSDR动态稀疏线的种群平均值;另一个物种边界线（I）的斜率是由于将边界定位在所有观测值上方而不考虑个别林分的自疏模式。混合效应分析被用来估计MSDR物种边界线II的斜率。
Maximum size-density relationships (MSDR) provide natural resource managers useful information about the relationship between tree density and average tree size. Obtaining a valid estimate of how maximum tree density changes with changes in average tree size is necessary to describe these biological relationships accurately. This article examines three methods to estimate the slope (b) of the MSDR species boundary line across a range of planting densities: ordinary least-squares (OLS), first-difference model, and the linear mixed-effects model. For this article, stability refers to the extent to which parameter estimates do not change when the range of planting densities in the fitting data set changes. When using data from a planting density trial consisting of planting densities ranging from 6,727 to 747 seedlings per hectare, mixed-effect models produced the most stable estimates of b while OLS resulted in the least stable estimates. MSDR boundaries have been defined as either (1) those that describe the boundaries of individual stands (MSDR dynamic thinning line) or (2) those that describe MSDRs common across all sites for a particular species in a certain geographical region (MSDR species boundary line). A further refinement of the MSDR species boundary line is proposed by defining two MSDR species boundary lines, labeled here as I and II. Although both MSDR species boundary lines are positioned above all observations, one MSDR species boundary line, II, has a slope that can be considered the population average of all MSDR dynamic thinning lines; the other species boundary line (I) has a slope that results from positioning the boundary above all observations without accounting for self-thinning patterns of individual stands. A mixed-effects analysis was used to estimate the slope of MSDR species boundary line II.