Open Collections

Summers, Breanna

University of British Columbia

The impacts of overstory tree retention and climatic aridity on plant community assembly were studied in Douglas-fir dominated forests. There were observed declines in species richness, and percent cover of moss and lichens, in the low retention treatments. High overstory retention treatments conserved community composition, while clearcut and low retention treatments triggered distinct changes, with losses of shade tolerant indicator species and increases in invasive herbs. Low retention treatments reduced the presence of certain culturally important food plants. This study also examined the effects of tree retention and climatic aridity gradient on the performance of local and migrated Douglas fir genotypes and understory plant communities. Seedlings from arid climates and those under high overstory retention grew tallest, suggesting potential adaptability to increasingly arid conditions. Conversely, in humid climates, seedlings fared better in more open conditions, except where shrub cover was high. Understory plant communities played a role in sheltering seedlings from drought and frost, thus promoting their survival and growth. However, clearcutting exacerbated drought incidence due to increased plant competition for water. The retention of overstory trees mitigated the competitive effects of understory plant communities on seedlings. This study provides evidence that retention of overstory trees may protect plant species and regenerating seedlings under increasing aridity with climate change.

Text

2024-06-26

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88519

Forestry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/