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Providing evidence to improve practice

Individual study: Bird species richness and abundance decreased in forest plots treated with herbicide and manually thinned

Published source details

Easton W.E. & Martin K. (1998) The effect of vegetation management on breeding bird communities in British Columbia. Ecological Applications, 8, 1092-1103


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Apply herbicide to mid- and understorey vegetation Bird Conservation

A replicated, controlled study from May-July in 1992-1995 in three replicate plots of mixed forest in British Columbia, Canada (Easton & Martin 1998), found that bird species richness and abundance became more homogeneous after herbicide treatment of deciduous vegetation (with cut stems sprayed with glyphosate). Bird species richness declined by 25% and 11% in herbicide-treated and control sites respectively. Abundance of birds increased annually (no significant differences between the control and treated areas) due primarily to significant increases in numbers of common species. Herbicide-treated areas showed a greater turnover of bird species. Nesting success was lower in herbicide-treated areas (8%) than in control areas (28%). Treatments reduced the volume of deciduous trees by 90-96% by removing deciduous trees within 1 m of conifer seedlings, or that were 1 m taller than nearby conifers.

 

Manually control or remove midstorey and ground-level vegetation (including mowing, chaining, cutting etc) in forests Bird Conservation

A replicated, controlled study from May-July in 1992-1995 in three replicate plots of mixed forest in British Columbia, Canada (Easton & Martin 1998), found that bird abundance did not vary between sites with manual thinning of the mid- and understorey vegetation and controls, although thinned areas held fewer species than controls. Abundance of birds increased annually (no significant differences between the control and treated areas) due primarily to the significant increase in numbers of common species. Nesting success was higher in manually thinned areas (46%) than in controls (28%). Manual thinning reduced the volume of deciduous trees by 90-96 % by removing deciduous trees within 1 m of conifer seedlings, or that were 1 m taller than nearby conifers.