Data from: Prescribed fire and conifer removal promote positive understorey vegetation responses in oak woodlands

Fire-prone woodlands and savannas world-wide face management challenges
resulting from fire exclusion and subsequent encroachment of
fire-sensitive trees. In the Pacific Northwest (USA), Quercus garryana oak
woodlands and savannas are threatened by encroachment from the native
conifer Pseudotsuga menziesii in the absence of fire. In the Bald Hills of
Redwood National Park (California, USA), prescribed fire and conifer
removal have been used to restore encroached woodlands. We examined the
effects of encroachment and restoration on understorey vegetation,
comparing four treatments: prescribed fire, prescribed fire and conifer
removal, conifer removal, and encroached (control). Treatments including
prescribed fire had the greatest native species richness. These two
treatments also had the greatest non-native species richness, at both the
site level and the treatment level. Woodlands treated with conifer removal
and no prescribed fire were intermediate in species richness and diversity
compared to burned treatments and encroached woodlands. Encroached
woodlands had diminished richness and diversity compared to all
restoration treatments. Non-metric multidimensional scaling (NMS)
ordination demonstrated that conifer basal area, conifer litter and fine
wood were associated with low species richness and diversity and that
elevation and thatch were associated with higher species richness and
diversity. Indicator species analysis identified that most native species
and non-native species were associated with burned woodlands that were
never encroached. Synthesis and applications. Our results suggest that
both prescribed fire and conifer removal have benefits for understorey
plant communities, increasing species richness, diversity and cover in oak
woodlands and shifting understorey communities from forest-associated
species to more woodland-associated species. Restoration of remnant
Quercus garryana oak woodlands is complicated by the persistence and
abundance of non-native herbaceous plants.