Mechanical Mastication Showed Fewer Negative Above-and Belowground Impacts Than Slash Pile Burning

Mechanical Mastication Showed Fewer Negative Above-and Belowground Impacts Than Slash Pile Burning

Management designed to reduce wildfire risk must consider both above- and belowground factors in order to promote native plant growth and reduce soil erosion. This goal is challenging because current methods, such as tree thinning and burning the resulting slash, can create soil disturbances that favor exotic plants. We compared mechanical mastication to slash pile burning (both 6-months and 2.5-years post treatment) and untreated controls in pinyon-juniper (Pinus edulis-Juniperus osteosperma) woodland and measured soil properties, arbuscular mycorrhizal fungi (AMF) and understory plant composition. Our results showed slash pile burns had severely degraded soil properties, low plant and AMF abundance and richness and a dominance of exotic plant species compared to untreated or mastication plots. Only two variables differed between mastication and untreated plots 6-months post treatment: mastication had lower soil temperature and higher soil moisture. Mastication plots 2.5-years post treatment had more plant cover and richness than untreated plots or pile burns, although exotic plant richness and Bromus tectorum cover were also greater and AMF spore biovolume and richness were lower than untreated plots. In the short term, mastication is a preferable method as it creates fewer disturbances than pile burning, however long-term impacts of mastication need further study as they could affect native communities. Our results showed the manner in which woody debris is treated has an important influence on sustaining soil stability and native biodiversity.

https://digitalcommons.usu.edu/nafecology/sessions/mastication/2