Impacts of Mastication: Soil Seed Bank Responses to a Forest Thinning Treatment in Three Colorado (USA) Conifer Forest Types

Forests

Akasha M. Faist²  Heather Stone²  Erin A. Tripp²  Robert Wagner¹ 

[1] Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA; E-Mail;Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA; E-Mail:

关键词: conifer;    vegetation;    seed banks;    ponderosa;    Lodgepole;    pinyon-juniper;   

DOI  :  10.3390/f6093060

来源: mdpi

【 摘 要 】

Mastication is a forest fuel thinning treatment that involves chipping or shredding small trees and shrubs and depositing the material across the forest floor. By decreasing forest density mastication has been shown to lessen crown fire hazard, yet other impacts have only recently started to be studied. Our study evaluates how mastication treatments alter the density and composition of soil seed banks in three Colorado conifer forest types. The three forest types were (1) lodgepole pine, (2) ponderosa pine and (3) pinyon pine-juniper. Results showed that masticated sites contained higher seed bank densities than untreated sites: a pattern primarily driven by treatment effects in ponderosa pine forests. The seed bank was dominated by forbs regardless of forest type or treatment. This pattern of forb dominance was not observed in the aboveground vegetation cover as it demonstrated more even proportions of the functional groups. Graminoids showed a higher seed density in treated sites than untreated and, similarly, the identified non-native species only occurred in the treated ponderosa pine sites suggesting a potential belowground invasion for this forest type. These results suggest that presence of masticated material might not be creating a physical barrier hindering the transfer of seeds as predicted.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.