Long-term effects of post-harvest stump removal and N-fertilization on understory vegetation in Western USA forests

Abstract

Intensive forest management practices often disturb understory vegetation. and the recovery of these plant communities may depend on the type and severity of the disturbance. We examined the effects of stump removal and N-fertilization on understory plant communities and functional group (shrubs, graminoids, forbs, and introduced species) cover and diversity at five study areas in the Pacific Northwest of North America 24 to 28 years after treatment. Treatments at each study area included stumped and nonstumped controls as well as four levels of broadcast ammonium nitrate (0, 336, 672, and 1345 kg N/ha) in all combinations. Stumping had significant effects on community composition at all sites. and several plant species were associated (p < 0.05) with either controls or stumped plots. diversity of graminoids, forbs, and introduced species increased in stumped areas regionwide. stumping reduced cover and diversity of shrubs at some sites. cover of graminoids and forbs also increased in stumped plots at some study areas. forbs like Viola sempervirens were often indicators of stump removal whereas shrubs such as Acer circinatum tended to be associated with nonstumped plots. N-fertilization affected community composition at only one study area, and had no effect on cover or richness of functional groups. Stump removal has lasting impacts on plant communities and may make them more vulnerable to colonization by introduced species.

Citation

Kaye, Thomas N.; Blakely-Smith, Matt; Thies, Walter G. 2008. Long-term effects of post-harvest stump removal and N-fertilization on understory vegetation in Western USA forests. Forest Ecology and Management. 256: 732-740