Treesearch

Interactions among forests, forestry, and water remain a critical aspect of Forest Service land stewardship. Small, experimental watershed studies managed by Forest Service Research and Development have a long history of advancing science and management and have resulted in a rich collection of long-term data. Early work addressed effects of forestry practices in particular forest types and hydrologic regimes. Revegetation of experimentally treated watersheds and new questions and tools of science and management are leading to new uses of the long-term records for science, management, and...

We investigated how water transport capacity, wood density and wood anatomy were related to leaf photosynthetic traits in two lowland forests in Panama. Leaf-specific hydraulic conductivity (kL) of upper branches was positively correlated with maximum rates of net CO2, assimilation per unit leaf area (Aarea) and stomatal conductance (gs) across 20 species of canopy trees. Maximum kL showed stronger correlation with Aarea than initial kL suggesting that allocation to photosynthetic potential is proportional to maximum water transport capacity. Terminal branch kL was negatively correlated...

Ponderosa pine (Pinus ponderosa Dougl. exLaws.) is widely distributed in the western USA.We report the lack of stomatal closure at night in early summer for ponderosa pine at two of three sites investigated. Trees at a third site with lower nitrogen dioxide and nitric acid exposure, but greater drought stress, had slightly open stomata at night in early summer but closed stomata at night for the rest of the summer. The three sites had similar background ozone exposure during the summer of measurement (2001). Nighttime stomatal conductance (gs) ranged from one tenth to one fifth that of...

Climate warming may first show up in forests as increased growth, which occurs as warmer temperatures, increased carbon dioxide, and more precipitation encourage higher rates of photosynthesis. The second way that climate change may show up in forests is through changes in disturbance regimes—the long-term patterns of fire, drought, insects, and diseases that are basic to forest development. Advanced computer models are producing the first national-scale simulations of how ecosystems and fire regimes could change in the 21st century. In six of seven future scenarios run through one model,...

We describe methods for incorporating the effects of insects and diseases on coniferous forests into forest simulation models and discuss options for including this capability in the modeling work of the Interior Northwest Landscape Analysis System (INLAS) project. Insects and diseases are major disturbance agents in forested ecosystems in the Western United States, and over time, are responsible for major changes in forest composition and structure. Incorporating their effects into forest simulation models is difficult, especially the representation of large, episodic insect epidemics....

The Interior Northwest Landscape Analysis System is a partnership among researchers and natural resource managers from both the public and private sectors. The project is an effort to increase our understanding of the role of vegetative succession, natural disturbance, and management actions at the watershed scale. The effort will advance the development and application of integrated landscape-level planning tools (models, methods, and information) that use consistent assumptions and common data. Focusing on the subbasin (landscape units of about 202 300 ha) and smaller scales, we will...

This chapter describes the experimental site, the physical arrangement of treatment units and of measurement plots within units, and the silvicultural operations and vegetation measurements carried out from establishment in 1997-98 through 2002.

Silviculturists of the Olympia Forestry Sciences Laboratory, Pacific Northwest Research Station, have joined with foresters of the Washington State Department of Natural Resources and scientists of University of Washington and University of Idaho to establish a long-term comparison of silvicultural regimes for regeneration and management of young growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests. In this report we review the concerns that led to the study, the study design and methodology, and expected expansion over the next few years. We document establishment of the...

The Washington Department of Natural Resources (DNR) administers some 2.1 million acres of state forest land, much of it in the highly productive west-side Douglas-fir region. The primary objective—defined by law—is to generate income in perpetuity for trust beneficiaries consisting of educational and other state and county institutions. The DNR also must retain broad citizen support. Public concerns stemming from the visual effects of harvesting activities have become major considerations in DNR management decisions, especially along major travel routes. There is a need for sound quantitat...

We used data from regional forest inventories and research programs, coupled with mapped climatic and topographic information, to explore relationships and develop multiple linear regression (MLR) and regression tree models for total and deciduous shrub cover in the Oregon coastal province. Results from both types of models indicate that forest structure variables were most important for explaining both total and deciduous shrub cover. Four relationships were noted: (1) shrub cover was negatively associated with Tsuga heterophylla basal area and density of shade-tolerant trees; (2) shrub...