In post-disturbance grasslands in New Zealand shrubs can serve as nurse plants. However, while many canopy trees may establish under a shrub canopy, shade may also restrict seedling establishment. We assessed the potential of shrubs and canopy manipulations in restoring mature forest species in a stressful environment. Mountain beech (Fuscospora cliffortioides, Nothofagaceae) seedlings were planted in October 2015 and December 2016 in post-disturbance grasslands. Growth and survival were monitored over three growing seasons in five canopy treatments: open grassland, mānuka (Leptospermum scoparium, Myrtaceae) shrubland with intact canopy, mixed-species shrubland with intact canopy, artificial gaps in mānuka shrubland; and the grassland edge of the mixed-species shrubland. Understorey light transmission and canopy openness were quantified during the first growing season using hemispherical photos. Canopy manipulations caused significant differences in the light availability and canopy openness among treatments. We observed that seedlings performed better in the mānuka shrub with gap and mixed-species shrub canopies (intact and edge treatments), perhaps due to moderate canopy openness in these treatments compared to open grasslands and intact mānuka canopy. Growth and survival were positively associated with moderate log(light) levels, which correspond to light conditions in manuka with gaps and intact mixed-species shrubs and are likely to represent the net effects of these treatments. The results demonstrated that early-successional shrubs could be managed as nurse plants to control the effect of over-shading and facilitate the growth and survival of canopy species in a stressful environment.

中文翻译：

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在退化的高地国家，后期成功种对护士灌木操纵的早期反应

在新西兰发生灾后的草原上，灌木可以作为养护植物。但是，尽管许多冠层树可能会在灌木冠层下建立，但树荫也会限制幼苗的建立。我们评估了灌木和林冠处理在压力环境下恢复成熟森林物种的潜力。2015年10月和2016年12月在干扰后的草原上种植了山毛榉（Fuscospora cliffortioides，Nothofagaceae）幼苗。在五个冠层处理方法的三个生长季节中监测生长和存活：开阔的草地，mānuka（Leptospermum scoparium，桃金娘科）具有完整冠层的灌木丛，具有完整冠层的混合物种灌木丛，mānuka灌木丛中的人工间隙；以及混合物种灌木丛的草地边缘。使用半球形照片在第一个生长季节对下层透光率和树冠开放度进行了量化。冠层操纵导致治疗之间的光利用率和冠层开放度显着不同。我们观察到，在带有间隙和混合物种灌木冠层（完整和边缘处理）的mānuka灌木中，幼苗的表现更好，这可能是由于与开放草地和完整mānuka冠层相比，这些处理中的冠层开放度适中。生长和生存与中等log（light）水平呈正相关，对应于麦卢卡中有裂隙和完整混交灌木的光照条件，很可能代表了这些处理的净效果。结果表明，早期成功的灌木可以作为护理植物进行管理，以控制过度遮荫的影响并促进冠层物种在压力环境下的生长和生存。