Exotic conifers are rapidly spreading in many regions of New Zealand, as well as in many other countries, with detrimental impacts on both natural ecosystems and some productive sector environments. Herbicides, in particular the active ingredient triclopyr, are an important tool to manage invasive conifers, yet there is a paucity of information that quantifies the amount of herbicide required to kill trees of different sizes when applied as a basal bark treatment. Two sequential experiments were conducted to define the amount of triclopyr required to kill individual invasive lodgepole pine (Pinus contorta Douglas ex Loudon), trees of different sizes when applied in a methylated seed oil to bark (either the whole stem or base of the tree) and to determine which tree size variates (height, diameter at breast height [DBH], crown diameter [CD]) or derived attributes (crown area, crown volume index) best characterized this dose–response relationship. The outcomes of the dose–response research were compared with field operations where triclopyr was applied to the bark of trees from an aerial platform. Applying the herbicide to the whole stem, as opposed to the base of the tree only, significantly increased treatment efficacy. The tree size variates DBH, CD, crown area, and crown volume index all provided good fits to the tree mortality data, with >91% prediction accuracy. Of these variates, CD provided the most practical measure of tree size for ease of in-field calculation of dose by an operator. Herbicide rates used in field operations were seven to eight times higher than lethal doses calculated from experimental data. Our results highlight the potential for substantial reductions in herbicide rates for exotic conifer control, especially if dose–response data are combined with remotely sensed quantitative measurements of canopy area or volume using new precision technologies such as unmanned aerial vehicles.

中文翻译：

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优化树大小和剂量反应函数以控制侵入性扭曲松

异国情调的针叶树正在新西兰的许多地区以及许多其他国家迅速蔓延，对自然生态系统和一些生产部门环境造成不利影响。除草剂，特别是活性成分绿草定，是管理侵入性针叶树的重要工具，但在用作基础树皮处理时，缺乏量化杀死不同大小树木所需的除草剂数量的信息。进行了两个连续的实验来确定杀死单个侵入性松树所需的绿草定量（旋松Douglas ex Loudon），不同大小的树木在甲基化种子油中用于树皮（整个茎或树的基部）并确定不同的树木大小（高度、胸径 [DBH]、树冠直径 [ CD]）或衍生属性（牙冠面积、牙冠体积指数）最能表征这种剂量-反应关系。将剂量反应研究的结果与从空中平台将绿草定应用于树皮的现场操作进行了比较。将除草剂施用于整个茎，而不是仅施用于树的基部，显着提高了治疗效果。树木大小变化的 DBH、CD、树冠面积和树冠体积指数都很好地拟合了树木死亡率数据，预测准确度 > 91%。在这些变体中，CD 提供了最实用的树木大小测量方法，便于操作员现场计算剂量。田间作业中使用的除草剂用量比根据实验数据计算的致死剂量高出七到八倍。我们的研究结果强调了显着降低外来针叶树除草剂用量的潜力，特别是如果剂量反应数据与使用无人机等新的精密技术对冠层面积或体积的遥感定量测量相结合。