Logging in boreal field-forest ecotones promotes flower-visiting insect diversity and modifies insect community composition

Published source details Korpela E.-L., Hyvonen T. & Kuussaari M. (2015) Logging in boreal field-forest ecotones promotes flower-visiting insect diversity and modifies insect community composition. Insect Conservation and Diversity, 8, 152-162.
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This study is summarised as evidence for the following.

	Action	Category
	Manage woodland edges for maximum habitat heterogeneity Action Link
	Thin trees within forests Action Link

Manage woodland edges for maximum habitat heterogeneity

A replicated, paired, controlled, before-and-after study in 2009–2011 in 15 coniferous forest stands in Vihti and Jokioinen, Finland (Korpela et al. 2015) found that felling trees at the woodland edge, in addition to thinning the adjacent woodland, increased the abundance of specialist butterflies and the total species richness of butterflies, moths and bumblebees (Bombus spp.) combined. Two years after felling and thinning, the abundance of specialist butterflies (3.5 individuals/plot), and the total species richness of butterflies, moths and bumblebees (10.7 species/plot), were higher in felled forest edges than in forest edges which had not been felled (butterfly abundance: 0.5 individuals/plot; total richness: 3.6 species/plot). Prior to felling, both butterfly abundance and total species richness were similar in the plots designated for felling (butterfly abundance: 0.5 individuals/plot; total richness: 6.4 species/plot) and no felling plots (butterfly abundance: 0.7 individuals/plot; total richness: 6.2 species/plot). In winter 2009–2010, in each of 15 forest stands, a 50-m-long forest edge was logged. Logging comprised felling a 5-m-wide strip at the forest edge, and behind that a 20-m-wide belt was thinned to a basal area of 8 m²/ha. Trunks were removed, but other debris was left on the ground. A second 50 × 25 m area at each site, within 8–61 m of the logged area, was left unlogged. From late May–August 2009–2011, butterflies, diurnal moths and bumblebees were surveyed seven times/year in each logged and unlogged area, at two-week intervals.

(Summarised by: Andew Bladon)
Thin trees within forests

A replicated, paired, controlled, before-and-after study in 2009–2011 in 15 coniferous forest stands in Vihti and Jokioinen, Finland (Korpela et al. 2015) found that thinning trees near to the edge of woodland, in addition to felling the edge, increased the abundance of specialist butterflies and the total species richness of butterflies, diurnal moths and bumblebees (Bombus spp.) combined. Two years after thinning and felling, the abundance of specialist butterflies (2.3 individuals/plot), and the total species richness of butterflies, moths and bumblebees (7.3 species/plot), were higher in thinned areas than in areas which had not been thinned (butterfly abundance: 0.6 individuals/plot; total richness: 3.8 species/plot). Prior to thinning, both butterfly abundance and total species richness were similar in the plots designated for thinning (butterfly abundance: 0.6 individuals/plot; total richness: 4.9 species/plot) and no thinning plots (butterfly abundance: 0.5 individuals/plot; total richness: 5.3 species/plot). In winter 2009–2010, in each of 15 forest stands, a 50-m-long forest edge was logged. Logging comprised felling a 5-m-wide strip at the forest edge, and behind that a 20-m-wide belt was thinned to a basal area of 8 m²/ha. Trunks were removed, but other debris was left on the ground. A second 50 × 25 m area at each site, within 8–61 m of the logged area, was left unlogged. From late May–August 2009–2011, butterflies, diurnal moths and bumblebees were surveyed seven times/year in each thinned and unthinned area, at two-week intervals.

(Summarised by: Andrew Bladon)