Treesearch

Tree regeneration outcomes are challenging to generalize and difficult to predict. Many tree species can establish new propagules in a variety of post-disturbance environments and many different reproductive mechanisms may be used. In order to develop conceptual models that accurately reflect reproductive potential, we need a better understanding of the similarities in regeneration ecology among species. We used information from the forest ecology literature to evaluate the reproductive attributes of sixty-two tree species in the central hardwood region of the eastern United States. Each...

Two individual-tree growth simulators are used to predict the growth and mortality on a 30-year-old forest site and an 80-year-old forest site in eastern Kentucky. The empirical growth and yield model (NE-TWIGS) was developed to simulate short-term (

Red spruce (Picea rubens Sarg.) growing in northern montane forests of eastern North America appears to be distinctive with respect to at least two aspects of winter physiology. First, red spruce attains only a modest level of midwinter cold tolerance compared to other north temperate conifers and appears barely capable of avoiding freezing injury at commonly occurring ambient winter temperatures (DeHayes, 1992). Second, red spruce is capable of net photosynthesis during winter in response to relatively brief exposure to mild temperatures (Schaberg et al., 1995). Despite considerable...

Three important population processes occur during any biological invasion: arrival, establishment, and spread. Arrival is the process by which individual(s) of the invading organism are transported to their new habitat. Establishment can be considered the opposite of extinction and represents the growth of a newly arrived population sufficient such that extinction is impossible. Spread is the process by which the species expands its range into the new habitat. Because most biological invasions are caused by human activities, these activities are important to understanding the arrival...

The effects of five residual stand densities (9.2, 13.8, 16.1, 18.4 m2/ha, and an unthinned control (27.2 m2/ha)) on 10-year stand and crop tree growth and bole quality were studied in an even-aged red maple stand in Michigan. A secondary treatment of removing the understory trees (5-10 cm DBH) was applied on half the plots. Diameter growth was significantly greater in all cutting treatments than in the control. Ten-year diameter growth in the heaviest cut treatment was nearly three times that of the control. The interaction between understory removal treatments and density treatments was...

The wood-products industry is characterized by many small manufacturers that lack the staff to compile and analyze information on their operations and investments. Two computer programs, FRAN and JEFFI, have been developed by the USDA Forest Service at Princeton, West Virginia,to help small companies better analyze and monitor current performance, and better evaluate opportunities to expand operations, move into new product areas, or otherwise make additional investments. These financial management tools are described in detail.

Reports of reduced growth and vigor of forest trees in Europe and North America have been accumulating in recent years. In eastern North America, increased mortality and reduced radial growth rates have been noted for red spruce, frasier fir, and sugar maple. USDA Forest Service inventory data from permanent survey plots has revealed an unexpected reduction of radial growth (-50%) in natural pine forests over the past 30 years (Sheffield and Cost, 1987). Aluminum (Al) ions have been implicated as one of the main factors contributing to this decline on mineral soils at a pH below 5.5...

Oaks are a significant component of the hardwood forests of the Upper Midwest USA. Numerous species occur over vast areas in the region and are highly valued for a variety of reasons. Oak wilt caused by C. fagacearum, and oak decline associated with several factors are the major causes of the species, deterioration and death in the region. Urbanization and wind damage associated with spring storms have spurred the spread of oak wilt as well as contributed to general oak decline. Concern exists that additional increases in oak wilt may occur if the European oak bark beetle should become...

Relatively high deposition of nitrogen (N) in the northeastern United States has caused concern because sites could become N saturated. In the past, mass-balance studies have been used to monitor the N status of sites and to investigate the impact of increased N deposition. Typically, these efforts have focused on dissolved inorganic forms of N (DIN = NH4-N + NO3-N) and have largely ignored dissolved organic nitrogen (DON) due to difficulties in its analysis. Recent advances in the measurement of total dissolved nitrogen (TDN) have facilitated measurement of DON as the residual of TDN −...