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Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest
Author(s) -
Kane Jeffrey M.,
Varner J. Morgan,
Knapp Eric E.,
Powers Robert F.
Publication year - 2010
Publication title -
applied vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.096
H-Index - 64
eISSN - 1654-109X
pISSN - 1402-2001
DOI - 10.1111/j.1654-109x.2009.01062.x
Subject(s) - understory , species richness , shrub , vegetation (pathology) , forb , ecology , environmental science , biology , canopy , grassland , medicine , pathology
Questions: What influence does mechanical mastication and other fuel treatments have on: (1) canopy and forest floor response variables that influence understory plant development; (2) initial understory vegetation cover, diversity, and composition; and (3) shrub and non‐native species density in a second‐growth ponderosa pine forest. Location: Challenge Experimental Forest, northern Sierra Nevada, California, USA. Methods: We compared the effects of mastication only, mastication with supplemental treatments (tilling and prescribed fire), hand removal, and a control on initial understory vegetation response using a randomized complete block experimental design. Each block ( n =4) contained all five treatments and understory vegetation was surveyed within 0.04‐ha plots for each treatment. Results: While mastication alone and hand removal dramatically reduced the midstory vegetation, these treatments had little effect on understory richness compared with control. Prescribed fire after mastication increased native species richness by 150% (+6.0 species m 2 ) compared with control. However, this also increased non‐native species richness (+0.8 species m 2 ) and shrub seedling density (+24.7 stems m 2 ). Mastication followed by tilling resulted in increased non‐native forb density (+0.7 stems m 2 ). Conclusions: Mechanical mastication and hand removal treatments aided in reducing midstory fuels but did not increase understory plant diversity. The subsequent treatment of prescribed burning not only further reduced fire hazard, but also exposed mineral soil, which likely promoted native plant diversity. Some potential drawbacks to this treatment include an increase of non‐native species and stimulation of shrub seed germination, which could alter ecosystem functions and compromise fire hazard reduction in the long‐term.