Tl. Schoennagel et Dm. Waller, Understory responses to fire and artificial seeding in an eastern CascadesAbies grandis forest, USA, CAN J FORES, 29(9), 1999, pp. 1393-1401
Citations number
57
Categorie Soggetti
Plant Sciences
Journal title
CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE
To mitigate erosion after fire, land managers often seed non-native grasses
onto burned slopes. To assess how post-fire seeding affects plant recovery
, we compared areas that were either unseeded or artificially seeded after
high-intensity fire in a dry Abies grandis (Dougl.) Lindl. forest in the no
rtheastern Cascades. Seeding with a mix of non-native grasses and a legume
significantly reduced the cover of native plants and shifted patterns of re
lative abundance after 2 years. Although seeding did not significantly affe
ct total cover or native species richness, it reduced overall native plant
cover by 47%. Species that recolonize via wind-dispersed seeds (e.g., Epilo
bium angustifolium L., Lactuca serriola L., and Arenaria macrophylla Hook.)
, species with long-lived seeds that germinate after fire (e.g., Ceanothus
velutinus Dougl.), and species with wide successional amplitudes that respr
out after fire (e.g., Apocynum androsaemifolium L. and Salix scouleriana Ba
rratt) all declined steeply in cover on seeded plots. In addition, conifer
seedlings were only half as abundant on seeded plots. As seeding after fire
does not boost total plant cover and limits conifer tree establishment on
the study area, it appears to do little to reduce the risk of soil erosion.
It also appears to inhibit native shrub and herb re-establishment. These s
ubstantial effects on native species appear to alter plant communities well
beyond the life of the seeded species.