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Providing evidence to improve practice

Individual study: Thinning and chipping small-diameter ponderosa pine changes understory plant communities on the Colorado Front Range

Published source details

Wolk B. & Rocca M.E. (2009) Thinning and chipping small-diameter ponderosa pine changes understory plant communities on the Colorado Front Range. Forest Ecology and Management, 257, 85-95


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Thin trees within forests: effects on understory plants Forest Conservation

A replicated, controlled study in 1994-2005 in temperate coniferous forest in Colorado, USA (Wolk & Rocca 2009) found that thinning increased understory vegetation cover and the proportion of non-native species. Understory vegetation cover (unthinned: 3.9%; thinned: 6.1%; thinned and chipped: 7.1%) was higher in thinned and chipped plots than unthinned plots. The proportion of non-native understory species was higher in the thinning treatments (18% in both) than the unthinned treatment (14%), while the total number of species/1,000 m2 was similar between treatments (unthinned: 53; thinned: 47; thinned and chipped: 48).  Data was collected in 2005-2006 in 31 plots (1,000m2) established in 1994. Six plots were unthinned, 13 thinned (harvested matter removed from the site) and 12 were thinned and chipped (harvested matter chipped and distributed on the site).