Natural Regeneration of Douglas Fir and White Fir on Exposed Sites in the Sierra Nevada of California
Tappeiner JC and Helms JA. 1971. Natural Regeneration of Douglas Fir and White Fir on Exposed Sites in the Sierra Nevada of California. The American Midland Naturalist. 86(2):358-370
First- and 2nd-year survival and height growth of naturally regenerated white fir and douglas fir seedlings were studied in typical microenvironments on exposed slopes and ridge tops at an elevation of 1300 m in the Sierra Nevada of California. Microsites were described by measuring soil moisture at several depths and potential evaporation at 1st-year seedling height. Seedlings survive the summer drought apparently by attaining a type of dormancy in a suitable microsite. Survival was greatest in part shade and in full sun providing squaw carpet (Ceanothus prostratus) mats were present. In these microenvironments soil moisture reaches tensions of 15 atm and greater, but the reduced potential evaporation at the seedling tops probably compensates for the lack of soil moisture. The growth of natural regeneration is initially quite slow; however, mortality is essentially over by the 2nd year after germination. The all-age group structure of the mixed conifer stands on these sites is apparently related to the occurrence of microenvironments suitable for seedling establishment.
- Type
- Journal Article
- Authors
- Tappeiner, John; Helms, John
- Units
- SODN
- Keywords
- California, Douglas Fir, Ecology (Plant), Germination, Nevada, Regeneration, Sierra, White Fir