To gain a better foothold on the communication system of the
avifauna, calls and songs of the American Robin (Turdus migratorius)
were recorded and analyzed using the sound spectrograph. Ten different
calls were recognized as follows: three alarm calls, an excitement
call, challenge call, contact call, two flight calls and...
Controlling competing vegetation with the application of herbicides and increased seedling size at planting has been shown to increase seedling survival and growth. These two important reforestation tools have often been studied independently of each other, limiting comparisons that can be made between them. This study utilized a factorial treatment...
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RobinRose
Controlling competing vegetation with the application of herbicides and
Three studies were conducted to characterize and present early-seral
competition between Douglas-fir seedlings and the surrounding vegetation
communities during Pacific Northwest forest establishment. The first experiment
served as the foundation for this dissertation and was designed to quantify tradeoffs
associated with delaying forest establishment activities by introducing a fallow year...
A series of experiments were established to gain a better understanding of the extent to which Douglas-fir seeding root architecture may be manipulated and subsequent influences on seedling morphological and physiological development. The incorporation of amendments into nursery soils changed root architecture to some degree, but did not produce large...
Two-year-old ponderosa pine (Pinus ponderosa Laws.)
from two seed sources were grown at two nurseries. The
Fremont seed source was raised at Bend and Stone Nursery;
the Ochoco was grown at only the Bend Nursery. The
seedlings were fertilized in late September-early October
with nitrogen (N) or nitrogen plus potassium...
Ammonia (NH₃) volatilization can result in a substantial amount of surface applied nitrogen (N) being lost into the atmosphere, making it an environmental pollutant as well as reducing plant-available N. However, N can also be easily lost from the soil through leaching,
and nitrous oxide (NO₂). Enhanced efficiency N fertilizers...
Understanding the tradeoff between water use and productivity is critical for modeling growth of intensively managed Douglas-fir forests in the Pacific Northwest. Evapotranspiration is closely linked to carbon dioxide intake during the process of photosynthesis. However, summer drought characterizing the growing season in this region imposes a limit on carbon...
Windthrow has been studied extensively as a cause of mortality and as a landscape
disturbance agent in temperate forests throughout the United States. The effects of
windthrow mortality on stand species composition and structure, forest regeneration and
seral development have been well described at the site (e.g. single gap) and...