We conducted a large-scale, multiple-year study in harvested areas of Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco) forests in western Washington, examining the effectiveness of control methods on the widespread invasive shrub Scotch broom [Cytisus scoparius (L.) Link]. We tested both chemical and physical control methods, using three different approaches that are management relevant: (1) triclopyr, a POST herbicide, at different times of year and on different-sized plants; (2) cutting (or brushcutting) of mature individuals; and (3) scarification of soil surface to remove seedlings once versus multiple times. We measured initial mortality, seed germination, and percent cover of C. scoparius in plots for 3 yr following treatments. Triclopyr treatment resulted in greater mortality and reduced percent cover compared with all other treatments with the effect persisting for 2 yr after spraying. Further, triclopyr had the same effect on C. scoparius cover and mortality irrespective of time of year applied. Similar to soil scarification, triclopyr treatments resulted in a flush of seedlings, suggesting that removal of conspecific competitors and not soil disturbance per se promotes seed germination. Brushcutting was generally effective in reducing C. scoparius cover in the short term, but effects did not persist as long as triclopyr treatments, in part due to large differences in stump resprouting rates across sites. Soil scarification to remove seedlings, even over multiple years, did not result in reduced C. scoparius cover. Triclopyr is an effective approach for controlling both emerging and established stands of C. scoparius.

中文翻译：

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美国华盛顿西部森林空地入侵灌木 Cytisus scoparius 的化学和机械控制

我们在花旗松的采伐区进行了一项大规模、多年的研究（门氏假松[Mirbel] Franco) 位于华盛顿西部的森林，研究控制方法对广泛侵入的灌木 Scotch broom 的有效性 [大鲵(L.) 链接]。我们使用三种与管理相关的不同方法测试了化学和物理控制方法：（1）绿草定，一种 POST 除草剂，在一年中的不同时间和不同大小的植物上；（二）成熟个体的扦插（或刷割）；(3) 一次与多次松土除苗。我们测量了初始死亡率、种子发芽率和覆盖率C. scoparius在处理后 3 年的地块中。与所有其他处理相比，绿草定处理导致更高的死亡率和降低的覆盖百分比，喷洒后效果持续 2 年。此外，绿草定对C. scoparius覆盖率和死亡率，与一年中的时间无关。与土壤松土相似，绿草定处理导致幼苗涌现，这表明去除同种竞争者而不是土壤干扰本身促进种子发芽。割草通常能有效地减少C. scoparius短期内覆盖，但效果不会像绿草定处理那样持续，部分原因是不同地点的树桩再发芽率存在很大差异。去除幼苗的土壤松动，即使经过多年，也没有导致减少C. scoparius覆盖。绿草定是控制新兴和成熟林分的有效方法C. scoparius.