Nutrient limitation constrains tree growth in many managed forests. Nitrogen (N) is the most common limiting nutrient, but high N supply can shift limitation to other nutrients, particularly phosphorus (P) and the base cations calcium (Ca), magnesium (Mg), and potassium (K). As different soil minerals have different capacities to supply...
Drought events have been shown to impact species distributions and are predicted to increase in frequency as the climate changes. As this occurs, ecologists predict species distributions will shift dependent upon species ability to track climate. These shifts in species distribution are expected to be particularly acute in arid and...
Small mountainous watersheds are disproportionate sources of land-derived particulate organic matter (POM) to long-term sinks like lake bottoms and the ocean. As such, these ecosystems are an essential component of the global carbon cycle. The burial of POM in lacustrine and marine sediments contributes to the drawdown of atmospheric CO2...
Tropical island ecosystems have proven to be inordinately vulnerable to invasions by exotic plants and animals. Today these islands only contain small
remnant populations of the original flora and fauna, and these populations are facing increasing pressure from invasive plants. This paper attempts to answer four important questions whose solutions...
Regression equations applicable to biomass components of standsof western hemlock [Tsuga heterophylla (Raf.) Sarg.} were developedby destructive sampling of a thinned and an unthinned stand ofwestern hemlock near Seaside, Oregon. Equations predicted more live-branchbiomass and less dead-branch biomass per tree for the thinnedstand, but equations for biomass of foliage, twigs,...
Climate change and the increase in meteorological drought have generated global concern over the persistence of ecosystems already in decline from decreased moisture. Evidence suggests dryland ecosystems have been more impacted by drought because of their tightly coupled growth-water relationships and high sensitivity to environmental shift. Removal of competing vegetation...
Parcellization of the rural landscape threatens the provision of social, ecological and economic benefits to society due to loss of economies of scale. A continued provision requires new approaches to forest management for multiple, interconnected goals. I used interviews, archival records and field measurements to learn how select, experienced owners...
This dissertation investigated potential ecological limitations to seedling regeneration in young, seasonally dry, evergreen forest restoration plantations in northern Thailand. We explored whether recruitment of colonizing tree species in the restoration plantations can be attributed to seed dispersal mode (i.e. abiotic or animal dispersal) and seed size. We did this...
The application of modern land management practices beginning at the turn of the 20th century is widely believed to have dramatically transformed forest landscapes of the inland Pacific Northwest. Restoring historical conditions to make forests resilient to future climate and disturbance regimes is a major goal of federal forest managers....
Changes in climate caused by increased concentrations of carbon dioxide (CO₂) in the Earth’s atmosphere have led land and ocean surface temperatures to increase by 0.85°C and sea level to increase by 19 cm relative to preindustrial times. Global climate change will lead to further alterations in mean temperature and...