應用相對關係式推估桂竹及孟宗竹生物量

Using Allometric Equation to Predict Bamboo Biomass Based on Combined Data of Makino Bamboo (Phyllostachys Makinoi) and Moso Bamboo (Phyllostachys Pubescens)

本研究旨在探討不同相對關係式（allometric equation）推估桂竹（Phyllostachys makinoi Hook.）及孟宗竹（Phyllostachys makinoi Hayata.）地上部之生物量。研究區位於台灣中部地區，取樣數量分別為20株桂竹及25株孟宗竹，以不同徑級為取樣標準，並嘗試以合併兩樣本資料，建立適合模擬兩竹種的相對關係式。本研究採用四種相對關係式模擬之，分別為一般相對關係式、WBE相對關係式（I）、WBE相對關係式（II）及Ruark相對關係式模擬此2種竹類之生物量，並採用殘差均方根（RMSE）來比較模式間的模擬效果。模擬結果顯示Ruark相對關係式之RMSE值最小（1.41），而WBE相對關係式（II）RMSE值最大（16.70），此外一般相對關係式、WBE相對關係式（I）及Ruark相對關係式之RMSE值相近（1.41-1.85）。此結果意味著理論模式WBE相對關係式（II），a與b參數值分別為0.10與2.67，並不適於模擬竹木種類之生物量；然而當b參數值固定為2.67而a參數值求得為0.0378時，RMSE值則降低至1.85。此結果表示竹類亦能由理論模式WBE相對關係式（I）模擬，b參數值為2.67而a值則會隨物種及森林情況修正。 The purpose of this study was to adopt the different allometric models to predict the aboveground biomass of two bamboos of makino bamboo (Phyllostachys makinoi) and moso bamboo (Phyllostachys heterocycla). The study site was located in central Taiwan and the 20 and 25 bamboo samples were obtained based on diameter class for makino bamboo and moso bamboo. This study tried to combine the samples of these two bamboo species in order to develop an allometric relationship which can be suitable for these two bamboos. The four allometric equations were adopted to predict these samples, namely, the general allometric model, the WBE model (I), the WBE model (II) and the Ruark model. The predicted effects among the four models were compared by the RMSE. We found that the Ruark model had a smallest RMSE (1.41) while the WBE model (II) had a largest RMSE (16.70). Moreover, the general allometric model, WBE model (I) and Ruark model had a near RMSE (1.41-1.85). It was implicated that the theoretical model of WBE model (II) was not suitable for bamboo species, because the parameters a and b of this model were fixed as 0.1 and 2.67. Whereas, only the parameter b was fixed (2.67) and the parameter a was predicted as 0.0378, the RMSE were obviously reduced as 1.85. This result showed that bamboo plants also supported the theoretical model of the WBE model (I) that the parameter b can use 2.67 while the parameter a may vary with species and other forest conditions.

The purpose of this study was to adopt the different allometric models to predict the aboveground biomass of two bamboos of makino bamboo (Phyllostachys makinoi) and moso bamboo (Phyllostachys heterocycla). The study site was located in central Taiwan and the 20 and 25 bamboo samples were obtained based on diameter class for makino bamboo and moso bamboo. This study tried to combine the samples of these two bamboo species in order to develop an allometric relationship which can be suitable for these two bamboos. The four allometric equations were adopted to predict these samples, namely, the general allometric model, the WBE model (I), the WBE model (II) and the Ruark model. The predicted effects among the four models were compared by the RMSE. We found that the Ruark model had a smallest RMSE (1.41) while the WBE model (II) had a largest RMSE (16.70). Moreover, the general allometric model, WBE model (I) and Ruark model had a near RMSE (1.41-1.85). It was implicated that the theoretical model of WBE model (II) was not suitable for bamboo species, because the parameters a and b of this model were fixed as 0.1 and 2.67. Whereas, only the parameter b was fixed (2.67) and the parameter a was predicted as 0.0378, the RMSE were obviously reduced as 1.85. This result showed that bamboo plants also supported the theoretical model of the WBE model (I) that the parameter b can use 2.67 while the parameter a may vary with species and other forest conditions.