Silvicultural Potential Research Articles

Demographic response of tree juveniles to reduced-impact logging in a Costa Rican montane forest

We assessed diameter and height growth, and mortality in seedlings (individuals ≥0.3, but <1.5 m tall) and saplings (individuals ≥1.5 m tall, but <10 cm DBH) of five common canopy tree species in an oak–bamboo forest in the Costa Rican highlands (2600–2800 m elevation) 5 years after a controlled logging operation under two harvesting intensities (20 and 30% basal area removal of stems ≥10 cm DBH, respectively). The species were Quercus costaricensis, Q. copeyensis, Drymis granadensis, Ocotea austinii, and Weinmania pinnata. For seedlings, the overall 5-year mortality rate (exponential model) was significantly higher under the lightest harvest intensity while for saplings, no significant differences in mortality were detected among harvesting intensities. Also for all species combined, annual 5-year diameter and height growth rates did not differ significantly among harvesting intensities for seedlings, although saplings grew significantly better under the higher harvest intensity. Our results suggest that, as a whole, saplings of the study species were more responsive to overstory removal than seedlings. At the species level, however, Quercus showed the largest significant differences in growth rates across harvest intensities and also with respect to the other studied species in both size classes. Based on our findings, and given the high abundance of advance regeneration at the study site (especially for Quercus), we propose that Costa Rican oak–bamboo forests show promising silvicultural potential for timber management under low-impact logging prescriptions.

A New Species of Calamus (Palmae) from Java

Calamus is the largest genus of Palmae (Arecaceae) with about 370 mostly climbing (rattan) species (Uhl & Dransfield 1987). In Java, there are about 16 species (Backer & Bakhuizen van den Brink 1968); one of them, represented by specimens collected in April 1971 byJD during an expedition to Ujung Kulon, WestJava, is still undescribed. It seems important to describe and name this new species, particularly because it appears to have a cane of excellent quality for furniture manufacture and may have some silvicultural potential.

A forest ecosystem guide for the Amos Lowlands Ecological Region, northwestern Quebec: A forest management approach

In Quebec, forest stations are defined as forest units that are reasonably homogeneous in terms of forest composition and site characteristics - as expressed by surficial deposit and moisture regime - and within which similar operational constraints for silvicultural potential and productivity levels may be expected. In the course of developing a field guide to the forest stations of the Amos Lowlands Ecological Region in northwestern Quebec, classifications of 12 site types and 72 forest stations (38 forest cover types or 16 general cover types) were developed. The classifications were based on a hybrid approach involving cluster analysis of forest ecological units inventoried in subregional studies, classical classification and ordination analyses performed on a regional biophysical inventory database, and empirically associating forest cover types to site types. The guide, while similar to other published forest ecosystem classification guides, emphasizes forest dynamics by presenting forest stations common to a given site type according to their successional stage. Field keys and general interpretations of forest potential and operational constraints are included in the guide. A summary description of the guide and accompanying documents is provided. A first draft has been distributed recently for feedback from industrial and government foresters and researchers in the region. Analyses of inventory data is continuing and modifications will be incorporated into a second draft before publication in 1995.

Studying global change: The contribution of Quaternary palynology

Quaternary palynological data have a fundamental contribution to make to studies of These data represent the most widely available quantitative record of past climates and as such can be used to validate the General Circulation Models (GCM's) that are used to ' simulate future climates (COHMAP Members, 1988). Without independent quantitative reconstructions of paleoclimates different from that of the present, GCM's are validated only by their capacity to simulate the present climate. The accuracy of their climate simulations for physical boundary conditions (including inter alia solar radiation flux, atmospheric CO2 concentration, global ice-volume and seasurface temperatures) substantially different from those of today can be assessed only by comparison with independent paleoclimatic indicators. When synthesized and mapped in appropriate ways, Quaternary palynological data can also enable the generation and/or testing of independent hypotheses as to how the atmospheric circulation, and as a result the climate, have responded to past changes in physical boundary conditions. The record of past vegetation change will, in addition, provide valuable indications as to how vegetation will respond to the changed climates of the future, and this will in turn provide information as to the future agricultural and silvicultural potential of various regions. Quaternary palynological data can also be used to assess the relative importance of environmental change as opposed to independent human interference in bringing about past changes in vegetation. This will in turn allow some assessment of the relative importance of various human activities in the context of global environmental change. A large body of data exists that can be used for these purposes. Most of the techniques required to utilize these data in these ways are available in at least a basic form and are the subject of current research. The components of the available database and the various classes of technique, and their current state of development, are outlined below. A Research Plan is then proposed that would exploit the data and techniques tha t have been developed by Quaternary palynologists. The proposed research would be interdisciplinary and would follow the model of the Cooperative Holocene Mapping (COHMAP) Project (Webb et al., 1985; Webb et al., 1987; COHMAP Members, 1988). This research will be a vital component of the whole effort to understand how climate changes in response to changes in the physical boundary conditions acting upon the atmosphere, and how vegetation in turn responds to and may influence these climate changes.

Living on the edge—the development of silviculture in South Australian pine plantations

Summary South Australia has one of the world's oldest man-made forests based upon classical sustained-yield management and funded totally from loans. Necessity to augment scarce local supplies of timber, in a climate “not naturally conducive to tall forest growth”, was realised over 120 years ago. The development of silviculture, from species selection and marketing factors through extensive, low cost practices into the current, highly intensive ones, is reviewed historically. A number of crises have been resolved and each has led to a greater understanding of silvicultural potential. Philosophical considerations that have inspired the development of silviculture to capture much of the great potential shown by the principal commercial species, Pirtus radiata, include a review of the scarce resources that have to be met by forest managers. A strongly-sustained demand for local supplies of timber and a limited land base support the continuation of intensive development in the future. This envisages conservation of site-based resources augmented by legume culture and judicious use of fertiliser mixtures. Safer formulations and more efficient supply systems allied with site-specific silviculture and vigorous application of tree-breeding are likely to lead to further refinement of silviculture.

The Silvicultural Potential of Mixed Stands of Cherrybark Oak and American Sycamore: Spacing Is the Key

Abstract The interaction of planted cherrybark oak (Quercus falcata var. pagodifolia Ell.) and American sycamore (Platanus occidentalis L.) was investigated on a flood plain of a minor stream in Arkansas. Oaks growing 20 ft or more from a sycamore attained a dominant position by 24 years, butwere still smaller in diameter and height than dominant sycamores. Rapid height and diameter growth of sycamore tends to retard oaks growing close to the sycamores. After 24 years, height and diameter differences between dominant oaks and sycamores are beginning to narrow, suggesting thatoaks may become more prominent. South. J. Appl. For. 11(3):158-161.

Tree Breeding and Genetics of Exotic Conifers in Canada

The most commonly planted exotic conifers in Canada are Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) Norway spruce has its highest potential on acid soils in high precipitation areas where it is more productive than the local spruce and fir mixture. Extensive plantations of Norway spruce have not been established because of its susceptibility to attack by white pine weevil. A number of provenance experiments have been established, and selection and breeding for resistance to the white pine weevil appear promising.Scots pine has not been favoured for timber production in Canada mainly because most early seed imports came from poorly formed stands in western Germany. Rapid early growth and green foliage in early winter led to extensive cultivation of these German types for Christmas trees. A limited number of stands from Poland and White Russia, and nearly all the Scots pine from Estonia-Latvia (Riga Pine) are well formed and are recommended for timber production, but not for the growing of Christmas trees. On less fertile sites, Scots pine grows more rapidly than red pine but, at least in the first 20 years, it does not grow as well as jack pine. Selected provenances of Scots pine hold much promise in the prairie region and in the boreal forest.Other exotic spruces have not been widely planted in Canada so very little is known about their silvicultural potential and ecological amplitude. Combined species and provenance trials have been planted recently to remedy this situation. A hybrid between Serbian and black spruce growing at Chalk River, Ontario has grown more rapidly than either parental species. Other species hybrids have been made, but are not yet assessed.In an attempt to develop a hard pine of wider ecological amplitude than red pine, species hybrids have been made between Scots pine, Japanese red pine and varieties of Pinus nigra. These are promising on rich soils in southern Ontario and might be extended further to the north and to poorer acid soils by using selected provenances for the breeding work. Pitch pine has been successfully crossed with P. taeda and P. radiata in an attempt to improve the productivity and potential of pitch pine.