Treesearch

The western pine beetle, Dendroctonus brevicomis LeConte, is a major cause of ponderosa pine, Pinus ponderosa Dougl. Ex Laws., mortality in the western USA and particularly in California. Under certain conditions, the beetle can aggressively attack and kill apparently healthy trees of all ages and size classes. The average loss is substantial, and has been estimated at 1 billion board feet annually. The availability of pest management techniques for preventing and suppressing infestations is rather limited. Currently, we are conducting several studies on the development of chemical,...

An understanding of natural regeneration processes, and the stand structural features that influence those processes, is vital to attaining goals associated with natural regeneration. This paper discusses natural regeneration concepts and the interactions that occur between shrubs and natural regeneration of ponderosa pine. The interactions observed recently in a series of related seedling recruitment studies in central Oregon are summarized. Evidence suggests a positive relationship between shrubs and the occurrence of ponderosa pine seedlings during the first two years of the seedling...

The soils of the central Oregon pumice plateau are relatively young and infertile, yet support an array of plant diversity and growth in the region's pine forests. Whether these coarse-textured, pumice and ash soils are resilient to forest disturbance is not well understood. We present results from a long-term experiment that examined changes in soil quality in response to combinations of thinning and repeated prescribed fire. Soil quality was generally unaffected in fifteen years following pre-commercial thinning. The soils were also resilient to fire with the exception of the loss of...

In the last several decades there has been a growing awareness of the value of snags in forests. Recent work has resulted in management standards and guidelines that set objectives for species such as cavity-nesting birds, but the numbers of snags required may not be attainable or sustainable across the landscape. Work reported here on snag demography in eastside pine forests was initiated in 1989. While snags have been present on most of the sites throughout the study period, the number of snags and their "life-spans" depends on tree species, tree size, soil characteristics, and topography...

The results of a series of replicated fertilization trials established throughout the Inland Northwest were reviewed for information specific to ponderosa pine (Pinus ponderosa P. and C. Lawson) nutrition. Ponderosa pine nitrogen (N) status was often better than the N-status of other Inland Northwest species, and therefore growth response to N fertilization was often lower than that of other species. Fertilization of ponderosa pine with N alone sometimes appeared to cause increased tree susceptibility to mortality by insect, disease and perhaps abiotic stresses. Growth and mortality...

This paper provides a selected list of classical references for the important silvicultural findings for ponderosa pine, and categorizes some of the key current literature, as well as some of the older, lesser known but important literature. The paper also provides some history of scientific developments, and sources of further information.

Silviculturists have primarily relied on classical even-aged silvicultural systems (the planned series of treatments for tending, harvesting, and re-establishing a stand) for ponderosa pine, with uneven-aged systems used to a lesser degree. Current management practices involve greater innovation because of conflicting management objectives. Silvicultural systems used in the foreseeable future will likely meld traditional systems with greater reliance on variation across the landscape because of differing values and desired outputs. Significant changes in the management of ponderosa pine...

Ponderosa pine (Pinus ponderosa P. & C. Lawson) is highly suitable for management using multiaged systems. This suitability is primarily the result of a frequent, low severity disturbance regime, but also because it naturally occurs at low densities and has a long history of management to promote multiple age classes. Several different stocking control tools are available for ponderosa pine including the q-factor, allocation of stand density index, and allocation of growing space represented by leaf area. These methods are applicable to pure or mixed stands. The productivity of multiaged...

In the 1960s a series of levels-of-growing-stock studies was established in young, even-aged stands throughout the range of ponderosa pine in the western United States. Using a common study plan, installations were begun in the Black Hills of South Dakota, eastern and central Oregon, the Coconino Plateau of Arizona and the west slope of the Sierra Nevada in California. Innovative features for the time were tests of a wide range of stand densities from open-grown to densities high enough to jeopardize stand health, and to periodic rethinning of the plots back to the stand density level...

This paper describes implementation and early results of a large-scale, interdisciplinary experiment in the Goosenest Adaptive Management Area in northeastern California. The study is designed to investigate development of late-successional forest attributes in second-growth ponderosa pine stands. The experiment has four treatments replicated five times and encompasses 1600 hectares, including controls. Complete treatment implementation took five years, including application of prescribed fire. Initial post-treatment measurements were conducted in 2002. Change in quadratic mean diameter...