The shelterbelt component of Canada’s whole-farm model Holos was upgraded from an age-determined to a circumference-determined (at breast height) calculation using a multi-stem averaging approach. The model interface was developed around the idea that a shelterbelt could have multiple rows, and a variable species composition within each row. With this, the model calculates the accumulated aboveground carbon in the standing biomass and a lookup table of modeled tree growth is used to add estimates of the belowground carbon. Going from an initial interface that asks for the current state, the model also incorporates an option of past and future shelterbelt plantings. In order to test the model’s suitability, we measured diverse shelterbelts (evergreen, deciduous, shrub type) in southern Saskatchewan, Canada representing commonly planted woody species. By making use of Caragana, Green Ash, Colorado Spruce, Siberian Elm, and a mixed Caragana/Green Ash tree row, we tested how many tree circumference measurements would be required to yield a representative average. Later, these results were incorporated in the Holos model to estimate the accumulated above- and below-ground carbon in each shelterbelt type.

中文翻译：

---

Holos 模型中改进的防护带组件的演示和测试

加拿大全农场模型 Holos 的防护林组件使用多茎平均方法从年龄确定升级为周长确定（胸高）计算。模型界面是围绕这样一个想法开发的，即防护林可以有多行，每行内的物种组成可变。有了这个，模型计算了站立生物量中累积的地上碳，并使用模拟树木生长的查找表来添加地下碳的估计值。从询问当前状态的初始界面出发，该模型还包含过去和未来防护林种植的选项。为了测试模型的适用性，我们测量了萨斯喀彻温省南部的各种防护林（常绿、落叶、灌木类型），加拿大代表普遍种植的木本物种。通过使用 Caragana、Green Ash、Colorado Spruce、Siberian Elm 和混合 Caragana/Green Ash 树行，我们测试了需要多少树木周长测量才能产生具有代表性的平均值。后来，这些结果被纳入 Holos 模型，以估计每种防护林类型中累积的地上和地下碳。