At the abrupt ecotone between the upper limit of southern beech forests in New Zealand and adjacent subalpine vegetation, ecological processes such as competition/facilitation, and species’ tolerances to alpine conditions, maintain a dynamic balance between these two contrasting plant communities. While other treeline ecotones globally have responded to ongoing climatic changes there is little evidence that the position and form of the beech-subalpine ecotone has undergone similar changes over the past decades. Further, it is unknown when the beech forest-subalpine ecotone will respond to such changes in the future. Critical to predicting change is understanding the abiotic and biotic factors that limit recruitment of individual trees above the treeline. To address this, this thesis research aimed to further elucidate the role of subalpine microhabitat variability in controlling forest regeneration patterns in abrupt treeline ecotones.