Individual study: Long-term impacts of even-aged timber management on abundance and body condition of terrestrial amphibians in Northwestern California
Karraker N.E. & Welsh H.H. (2006) Long-term impacts of even-aged timber management on abundance and body condition of terrestrial amphibians in Northwestern California. Biological Conservation, 131, 132-140
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Thin trees within forests
A site comparison study in 2000–2002 of 10 sites within a conifer-hardwood forest in California, USA (Karraker & Welsh 2006) found that thinning increased amphibian abundance, apart from ensatinas Ensatina eschscholtzii, and lowered the body condition of ensatinas, ten years after harvest. Overall, captures were significantly higher in thinned (7/1000 capture nights) compared to unthinned (4) and clearcut forest (4). However, abundance of the dominant species, ensatina, was similar in thinned (148 captures), unthinned (106) and clearcut forests (159). The body condition index of ensatinas was significantly lower in thinned compared to unthinned forests. Five thinned (aged > 10 years) and five unharvested forest stands adjacent to clearcuts (aged 6–25 years) were selected. Forest had been thinned (approximately 50% retained) prior to clearcutting. Amphibians were monitored using seven drift-fences with pitfall traps and artificial coverboards along two 150 m transects/site. Traps were checked weekly in October–December and April–June 2000–2002.