Stanley P. Gessel

Radiata pine plantations in Chile

The landscape of the southcentral part of Chile is dominated by fast-growing plantations of radiata pine (Pinus radiata D. Don), and in lesser extent bluegum eucalyptus (Eucalyptus globulus Labill.), Italian poplar, and willows. Radiata pine was first introduced in 1885 as an ornamental species. During 1940–1960 it was used to control erosion in the Coastal Range. Finally, since the 1960s it has been used for commercial plantations. The present extent of the plantation resource is 1,694,104 ha, of which 80.9 percent is radiata pine. During 1991, 1992, and 1993, this species was planted at rates of 75,416 ha, 81,868 ha, and 71,411 ha, respectively. Even though the soils are eroded to different degrees, exhibit a variety of nutritional disorders, and contain some physical restrictions, the productivity of radiata pine ranges from 18 m3/ha/yr to 35 m3/ha/yr. Additional stress comes from some potentially serious pests; for example, the European pine shoot moth, Rhyacionia buoliana, has presented a real threat to radiata pine. The main products obtained from radiata pine are exported to Japan, Korea, Middle and Far East countries, and Europe. Sawlogs, sawntimber, pulpwood, clearwood, and wood chips are some of the products comprising sales in 1994 of U.S.

Forest fertilization research and practice in the Pacific Northwest

1,564 billion.

Sustainable management of native and exotic plantations in Australia

Forest managers in the Pacific Northwest (PNW) use fertilization as a means to increase timber yields in managed stands. Information on the biological basis for nutrient amendments and stand growth responses to fertilization is required to effectively use fertilization as a silvicultural tool, and research programs in mineral cycling and forest nutrition have been underway in the region for about four decades.Most PNW Douglas-fir forest sites are nitrogen deficient. Mineral cycling research has shown high C/N ratios and low nitrification rates for soils in the region.Research and development projects in the Pacific Northwest have produced an information base that is used to select sites and stands for fertilization and to forecast growth after treatment. Much of the basis for operational fertilization programs in western Oregon and Washington comes from cooperative research programs; current activities for these programs are directed toward improving site-specific response information.Forest fertilization in the Pacific Northwest has become a silvicultural practice of major significance over the past two decades. Forest industry and government organizations managing forest lands in western Oregon and Washington apply nitrogen fertilizer to Douglas-fir stands over a range of soil and stand types (operational fertilization of other species is minor). About 50,000 to 55,000 ha are fertilized each year, and future programs will likely be of similar magnitude. Most current plans for management regimes including fertilization call for multiple applications.

Major-element deficiencies inCasuarina equisetifolia

The emphasis of plantation management changes as the resource and the market develop. This is especially the case when a plantation program is developing a new timber resource, is not the case with many of the Pinus radiata (D. Don) plantings in the southern hemisphere. Australia establishes and manages plantations of both exotic conifer and native hardwood (Eucalyptus spp.) plantations, and these vary in their stage of development. The tenure and objectives in establishment have varied, but some key aspects of the resources may be analyzed. Optimization of production per unit area was not a prime objective during the developmental stages of many exotic pine plantations. Currently, with increased commercial emphasis, this has changed to a greater focus on increased value through Site Specific Management and tree improvement through which gains of at least 20 percent are expected during the first stages. With a key objective of sustainability, questions regarding impacts of soils, water, and biological changes need consideration and are being addressed.The eucalypt plantation resource in Australia is smaller in extent than is the pine resource, but of increasing importance, especially as the plantations are perceived to be more environmentally and ecologically acceptable than exotic conifers. In the past, questions of productivity, especially in relation to impacts of natural pests and diseases, have been raised. Sustainability of all plantations is a critical aspect, however, for specific issues there are different emphases with different species. For example, the relatively, high removal of calcium in smooth barked Eucalyptus plantations is seen as important in long term forest management.

Nitrogen requirements in young Douglas-fir of the Pacific North-west

Casuarina equisetifolia is being widely used in tropical and sub-tropical countries as a fast-growing multipurpose tree. It is tolerant of relatively infertile sites, especially because of symbiotic N-fixation. However, mineral requirements and deficiencies have been scantily studied, even though responses to fertilization have been reported. To study its mineral nutrition, seedlings ofC. equisetifolia were grown for six months in sand cultures, using a 1/2 strength Hoagland-typeComplete solution, and two reduced levels of N, P, K, Ca, and Mg. Plant heights were measured every 2–3 weeks; at harvest, dry weights of younger and older foliage, stems, and roots were recorded, and chemical analyses made for the elements being studied. Deficiency symptoms were observed, and the chemical analyses confirmed at least incipient deficiency in the reduced level treatments for each of the five elements. This made possible estimation of deficiency ranges, which should be useful in assessing needs for mineral fertilization.

Use of foliage sulphate concentrations to predict response to urea application by Douglas-fir

A series of fourteen Pacific North-west Douglas-fir installations, ranging in age from 6 to 26 years were analysed with respect to site factors, foliage nutrients, and growth response to applied fertilizer. Unfertilized basal area increment ranged from 1.2 to 3.1 m2 ha−1 yr−1 with no apparent relationship with soil, stand age or site index. Basal area increment was correlated with foliage N and a critical level for N was calculated as 1.7%. Applications of 220 kg N ha−1 as urea increased growth between 0 and 95% of the unfertilized basal area growth, with an average of 24.9%. Response could be predicted from foliage N and unfertilized basal area increment. When the same relationships were applied to previously older stand data, results were more variable as elements such as B and S showed evidence of being limiting.