- 期刊
應用Weibull機率密度函數模擬不同經營型態麻竹與孟宗竹之林分結構
Predicting stand structure and carbon storage for ma bamboo (Dendrocalamus latiflorus) and moso bamboo (Phyllostachys pubescens) plantations subjected to different management types in central Taiwan
摘要
本研究之目的在於探討麻竹與孟宗竹之林分直徑分布，採用臺灣中部地區的麻竹與孟宗竹林分進行分析，各竹種具有不同經營型態林分，每一竹種具有6個林分，共計12個林分。經分析結果發現部分之林分性狀值（如林分平均胸徑及林分密度）和林齡結構在林分之間有很大的差異，甚至在同一竹種相同經營方式的林分之間也有很大的差異性。在竹林林分直徑分布之量化，本研究以Weibull機率密度函數進行模擬，採用最大概似法及百分位數法兩種方法求解Weibull函數之參數值，模擬後以Kolmogorov-Smirnov統計檢測其適合度，所得結果顯示最大概似法較百分位數法為佳，兩竹種以最大概似法模擬之通過率均高達100%，百分位數法則皆同為66.67%。茲以最大概似法為例說明Weibull分布之a、b、c範圍，麻竹分別為：0.92-4.50、1.96-7.00、1.41-8.20；孟宗竹則分別為：0-6.35、3.84-6.97、2.95-4.64。此結果也證實不論何種經營型態的竹林，兩竹種皆以最大概似法的模擬效果較佳。
並列摘要
The purpose of this study was to predict diameter distributions of ma bamboo (Dendrocalamus latiflorus) and moso bamboo (Phyllostachys pubescens) plantations. A total of 12 plantations were surveyed and each bamboo shared 6 plantations with different management types. These bamboo plantations were located in central Taiwan. We found that some of stand characteristics (e.g., mean diameter at breast height and stand density) and the age structure had large variations even in the same management types for the two bamboos. The Weibull probability density function was applied to quantify stand diameter distributions based on the maximum likelihood estimator (MLE) and percentile estimators (PE). We utilized the Kolmogorov- Smirnov test to examine the goodness-of-fit for the observations and the Weibull distribution predicted using the two approaches and found that MLE was superior to the PE. The pass rates of MLE and PE were 100 and 66.67% for ma bamboos, respectively. The same pass rates of MLE and PE were also shown in moso bamboo. We used the MLE as an example to reveal the ranges of the 3 parameters of Weibull distributions where the parameters a, b and c were 0.92-4.50, 1.96-7.00 and 1.41-8.20 for ma bamboo; and 0-6.35, 3.84-6.97 and 2.95- 4.64 for moso bamboo, respectively. It implicated that MLE was the best estimator to predict diameter distributions for these two bamboos, regardless of management types.