...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Forest Planning >A Model for Predicting the Vertical Distribution of Cross-sectional Area Increments in Hinoki Cypress Stems
【24h】

A Model for Predicting the Vertical Distribution of Cross-sectional Area Increments in Hinoki Cypress Stems

机译：扁柏树茎截面积增加量垂直分布的预测模型

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

To confirm that the vertical distribution of stem cross-sectional area increment (CSAI) for Hinoki cypress can be described by two straight lines derived from three tree attributes: sunny crown length (CL), stem volume increment (SVT), and CSAI at thebase of the sunny crown (CSAI_(CL)), two model were constructed and compared. One is the unrestricted model for describing the vertical distribution of CSAI by two straight lines (CSAI_(z))=az and CSAI_(z))=b+cz where CSAI_(z) is the CSAI at a distancez from the apex, and a, b, and c are parameters), and the other is the restricted model imposed two restrictions on the unrestricted model: (i) the two straight lines intersect at the coordinates (CL, CSAI_(CL)), (ii) the area of the diagram formed fromthe two straight lines is equal to the SVI. AKAIKE'S information criterion (AIC) and root mean square error (RMSE) were used to identify the better model. Data were obtained from 112 sample trees selected in six pure stands of even-aged Hinoki cypress. Parameters in the unrestricted model were estimated from CSAI dataset using least-squares method, and those in the restricted model were calculated from measurements of CL, SVI, and CSAI_(CL) for each sample tree. The unrestricted model fit well to CSAI observations, indicating that the vertical distribution of CSAI can be described by two straight lines. The AIC value for the restricted model was smaller than that for the unrestricted model, indicating that the restricted model is superior to the unrestricted model in describing the vertical distribution of CSAI. Although the restricted model returned a larger RMSE value than the unrestricted model did, the difference in RMSE was small. In conclusion, the vertical distribution of CSAI for Hinoki cypress can be described by two straight lines derived from CL, SVI, and CSAI_(CL).
机译：为了确认Hinoki柏的茎截面积增加量（CSAI）的垂直分布可以通过从三个树属性中得出的两条直线来描述：晴天树冠长度（CL），茎量增加量（SVT）和基部的CSAI构造了阳光冠（CSAI_（CL））的两个模型并进行了比较。一种是不受限制的模型，用于通过两条直线（CSAI_（z））= az和CSAI_（z））= b + cz描述CSAI的垂直分布，其中CSAI_（z）是距离顶点z的CSAI，并且a，b和c是参数），另一个是受限模型对非受限模型施加两个限制：（i）两条直线在坐标（CL，CSAI_（CL））处相交，（ii）面积由两条直线形成的图的等式等于SVI。使用AKAIKE的信息标准（AIC）和均方根误差（RMSE）来识别更好的模型。数据来自在均匀年龄的扁柏的六个纯林中选择的112棵样本树。使用最小二乘法从CSAI数据集中估计非限制模型中的参数，并根据每个样本树的CL，SVI和CSAI_（CL）的测量值来计算限制模型中的参数。不受限制的模型非常适合CSAI观察，表明CSAI的垂直分布可以用两条直线描述。约束模型的AIC值小于非约束模型的AIC值，表明在描述CSAI的垂直分布方面，约束模型优于非约束模型。尽管受限模型返回的RMSE值大于非受限模型，但RMSE的差异很小。总之，可以使用从CL，SVI和CSAI_（CL）得出的两条直线来描述Hinoki柏树CSAI的垂直分布。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号