Variable response of butterflies and vegetation to elk herbivory: An exclosure experiment in ponderosa pine and aspen-mixed conifer forests

Published source details Kleintjes Neff P.K., Fettig S.M. & VanOverbeke D.R. (2007) Variable response of butterflies and vegetation to elk herbivory: An exclosure experiment in ponderosa pine and aspen-mixed conifer forests. The Southwestern Naturalist, 52, 1-14.
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This study is summarised as evidence for the following.

	Action	Category
	Remove, control or exclude vertebrate herbivores Action Link

Remove, control or exclude vertebrate herbivores

A replicated, randomized, paired, controlled study in 1997–2002 in a grassland and forest reserve in New Mexico, USA (Kleintjes Neff et al. 2007) found that forest areas where elk Cervus elaphus were excluded had a higher abundance and species richness of butterflies in one out of four years, but the number of butterflies was similar in the remaining years and in all grassland areas. In forest sites where elk were excluded, the abundance (91 individuals/site) and species richness (17 species) of butterflies was higher than in browsed sites in one of four years (abundance: 42 individuals/site; richness: 13 species), but was not significantly different in the other three years (excluded: 2–9 individuals/site/year, 5–6 species/year; browsed: 2 individuals/site/year, 4–6 species/year). In grassland sites, the abundance and species richness of butterflies was not significantly different between exclusion (abundance: 3–141 individuals/site/year; richness: 5–16 species/year) and browsed sites (abundance: 3–85 individuals/site/year; richness: 4–13 species/year). In 1997–1998, four areas of ponderosa pine Pinus ponderosa grassland and five areas of mixed forest were selected, and a 60 × 60 m exclosure was constructed randomly on half of each site. Exclosures were 3 m high with 10-cm wire fencing to exclude elk. Three grassland sites and one forest site were deliberately or accidentally burned during the experiment. In June–August 1999–2002, butterflies were surveyed 2–5 times/year along a 360-m-long zigzag transect through each exclosure and browsed site. Grassland sites were not surveyed in 2002. Skippers (Hesperiidae) were not identified to species.

(Summarised by: Andrew Bladon)