Invasive exotic tree and shrub species (woody weeds) form dense, monospecific stands in many areas of New Zealand. At some sites, the weed dies out naturally and is replaced by native species as succession proceeds, but at others the weed persists indefinitely. The ability to distinguish between these different trajectories is critical to effective weed management, but the conditions that determine successional outcomes remain poorly understood.
The species composition of the understory can be a key indicator of successional trajectories in the absence of disturbance at forested sites. We surveyed species composition and percent cover in the understory of 132 closed-canopy stands of 41 woody weed species throughout New Zealand as a first step in understanding potential successional trajectories in these weed populations. Twenty-seven weed species had zero, or very few, conspecific seedlings or saplings present beneath their own canopy.
Interaction between conifers and angiosperms in New Zealand’s podocarp–broadleaved forests is a topic of enduring interest. We aimed to determine if the often discontinuous regeneration of the podocarps Dacrydium cupressinum and Prumnopitys ferruginea can be attributed to their seedlings’ tolerating less shade than those of angiosperm canopy trees and/or to occupying a narrower range of light environments.
Descriptions of alpine climate in areas of high solar radiation are increasing, but there is a paucity of microclimate data for shaded alpine rock bluff ecosystems. These shaded systems are important because they represent plant habitats that are subject to unique climate drivers within the alpine ecosystem, but which are poorly characterised globally.