Action: Apply herbicide to trees
- One replicated, controlled, before-and-after study in South Africa found that using herbicide to control trees increased plant diversity but did not increase shrub cover.
- One randomized, replicated, controlled study in the UK found that herbicide treatment of trees increased the abundance of common heather seedlings.
Application of herbicide can be used to control problematic trees and may aid recovery of shrubland vegetation.
Supporting evidence from individual studies
A randomized, replicated, controlled study in 1979–1981 in a heathland in Cambridgeshire, UK (Marrs 1984) found that using herbicide to control silver birch Betula pendula saplings sometimes increased the abundance of heather Calluna vulgaris and birch seedlings while reducing the abundance of silver birch saplings. In one of three cases, plots treated with herbicide had more heather seedlings (64 seedlings/m2) than untreated plots (4 seedlings/m2). In three of three cases, plots treated with herbicide had fewer birch saplings (0–1 saplings/m2) than untreated plots (20 saplings /m2). However, in two of three cases, birch seedlings were more abundant in plots treated with herbicide (24–54 seedlings/m2) than in untreated plots (7 seedlings/m2). The herbicides fosamine, 2,4,5-T, and triclopyr were each applied in four 4 m2 plots in 1979, and in four plots no herbicide was applied. Density of birch and heather plants was estimated annually in 1980-1981 in all plots.
A replicated, controlled, before-and-after study in 2013–2014 in a fynbos site in Cape Town, South Africa (Krupek et al. 2016) found that spraying invasive orange wattle Acacia saligna trees with herbicide increased plant diversity, but not shrub cover. Plant species diversity was higher in areas treated with herbicide than in untreated areas (data presented as model results). However, shrub cover in areas treated with herbicide (2%) did not differ from untreated areas (5%). In April 2013 herbicide was sprayed on orange wattle saplings in ten 25 m2 plots, while another ten plots were left untreated. The cover and diversity of plant species was assessed using 1 m2 quadrats placed inside each plot.
- Marrs R.H. (1984) Birch control on lowland heaths: mechanical control and the application of selective herbicides by foliar spray. Journal of Applied Ecology, 21, 703-716
- Krupek A, Gaertner M., Holmes P.M. & Elser K.J. (2016) Assessment of post-burn removal methods for Acacia saligna in Cape Flats Sand Fynbos, with consideration of indigenous plant recovery. South African Journal of Botany, 105, 211-217