Silviculture of High-Quality Oaks: Questions and Future Research Needs Gt Weaver, H Spiecker

Silviculture of high-quality oaks: questions and future research needs Gt Weaver, H Spiecker

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Gt Weaver, H Spiecker. Silviculture of high-quality oaks: questions and future research needs. Annales des sciences forestières, INRA/EDP Sciences, 1993, 50 (6), pp.531-534. hal-00882863

HAL Id: hal-00882863 https://hal.archives-ouvertes.fr/hal-00882863 Submitted on 1 Jan 1993

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Silviculture of high-quality oaks: questions and future research needs

GT Weaver H Spiecker

1 Department of Forestry, Wildlife and Fisheries, The University of Tennessee, PO Box 1071, Knoxville, TN 37901-1071 USA; 2 Institut für Waldwachstum Bertoldstr 17, DW-7800 Freiburg, Germany

(Received 6 January 1993; accepted 2 June 1993)

Summary — Oak forests are economically and ecologically important in Central Europe and eastern United States of America. In the former oak forests are being returned by artificial regeneration to many sites where oaks had been replaced by other species. Artificial and natural regeneration methods are being sought. Coppice forests are being replaced by forests of seed origin on many sites throughout Central Europe. Methods using wider spacing and shorter rotations which produce high- quality timber adapted to site quality are being considered. In the USA reliable regeneration remains a key silvicultural problem. Effective means of both artificial and natural regeneration are being sought. Oak forest are and will be managed for a broader range of objectives in Central Europe and the USA. Future research needs include ecophysiology, growth and development, regeneration, silvicultural systems and oak decline.

Quercus spp / silviculture I ecology I coppice I high forest / Central Europe I USA

Résumé — Sylviculture des chênes de haute qualité. Questions et besoins en recherches fu- tures. Les forêts de chênes sont économiquement et écologiquement importantes en Europe et dans l’est des États-Unis d’Amérique. Dans le premier cas, les chênaies sont revenues grâce à la ré- génération artificielle sur de nombreux sites où elles avaient été remplacées par d’autres espèces. Des méthodes pour la régénération naturelle et artificielle sont recherchées. Les taillis sont rempla- cés par des futaies dans beaucoup d’endroits en Europe. Les méthodes utilisant de larges espace- ments et des rotations courtes qui produisent des bois de haute qualité adaptés aux stations sont maintenant prises en considération. Aux États-Unis, une régénération efficace reste une des clés de la sylviculture. Des moyens performants de mise en œuvre de la régénération artificielle et de la ré- génération naturelle sont recherchés. Les chênaies sont et seront aménagées pour un très large éventail d’objectifs en Europe et aux États-Unis. Les besoins futurs en recherche incluent l’écophy- siologie, la croissance et le développement, la régénération, les traitements sylvicoles et le dépéris- sement du chêne.

Quercus spp / sylviculture / écologie / taillis / forêt / Europe centrale / États-Unis INTRODUCTION preparing appropriate and effective prescriptions. stands affects The Technical Session of P1 06 "Improve- The history of present their current to treatment ment and Silviculture of Oaks", held during status, responses and for and ser- the IUFRO Centennial Meeting at Eber- potential producing goods vices. These factors have to be considered swalde/Berlin in 1992, has 2 principal when silvicultural goals: 1) to determine the status of oak sil- preparing prescriptions. forests continue to in viculture in Central Europe and the United Coppice predominate These forests often States; and 2) to identify research that many regions. produce stems of inferior and are supports future management of oaks and quality generally as less desirable than those from oak forests. regarded seeds or planted seedlings. A problem for Conditions, problems and trends identi- silviculturalists is to determine how best to fied by authors for various countries and convert these stands to high forests (those research needs have been summar- major originating from seed). Often, several age ized in this On behalf of the paper. partici- classes are unevenly distributed within at the sessions and those who will pants management units, which complicates re- benefit from the published papers, our generation and management for sustained gratitude and appreciation are expressed yield. to the authors for sharing their expertise Artificial regeneration by planting and di- and insights with us. rect seeding with a tendency towards wider spacing prevails in Central Europe. Nat- ural with various levels of PAST AND PRESENT regeneration weeding and tending have been successful in some regions. In the uplands of the The papers in this series stress the eco- United States, natural regeneration of oak nomic and ecological importance of oaks forests is much more common but is in- in the past and present in Central Europe completely understood and is unreliable and the United States. Their present eco- under many conditions. Regeneration of nomic importance is closely related to the oaks on high-quality sites is especially diffi- percentage of valued wood produced. cult and is a primary constraint to intensive Ecological importance is due to the wide oak silviculture. Techniques for overcom- range of climatic provinces and sites pres- ing this problem are being studied in sever- ently or formerly occupied by oaks, and al countries. their importance as components of the Ecophysiological factors, including wildlife habitat, and in the protection of soil drought resistance, light requirement and and water resources. However, many other environmental parameters have present oak forests are not naturally been studied for some important species. established and do not occupy the full Individual tree parameters (crown dimen- range of sites to which they are adapted. sion, stem diameter) and stand structure Conversely, many stands have been es- (density, age and species composition) tablished and treated by silvicultural pre- have been studied for several European scriptions with little consideration for suita- species. The relationship between growth bility taking into consideration differences and these parameters are known for some in site quality. The historical origins and species, but effective practices for estab- past treatment of these stands are often lishment, tending and thinning stands are uncertain and increase the uncertainty of inadequately known for most species. Tending and thinning of stands in Central regeneration of some oak species by plant- Europe have traditionally maintained ing may be successful using various shel- dense stands to produce wood with rela- terwood techniques in place of the more tively narrow growth rings. Slower growth traditionally used clearcutting method. Ad- was believed to be necessary for the de- ditional information on the ecophysiological sired wood quality. Oak decline is of major responses of many species to light levels, concern both in Central Europe and east- soil conditions and on growth relations of ern United States. Although specific caus- competing species will be needed to gen- es have not been identified, research indi- eralize prescriptions to other species and cates physiological stress due to interacting regions. The genetic diversity of many oak factors (site conditions, drought, insects, forests is unknown due to the uncertain ori- diseases, tree age, genetics). gins of stands, seed sources and, in the United States, to repeated high-grading of stands. Assessment of genetic status of FUTURE TRENDS stands and techniques for genetic improve- ment of stands being regenerated are needed. Interest in both the economic and the ecological value of oaks will continue and Restoration of natural oak woodland probably increase in the future in Central communities in Central Europe is of in- interest. selection and Europe and the United States. When eco- creasing Species nomic return is the goal, emphasis will be silvicultural treatments should be adapted to sites and include mixtures of non-oak on high forests managed for maximum pro- ductivity - either through short rotation species. These forests will be managed in- as sustainable for a crops or on longer rotations for high valued creasingly ecosystems timber. Past criteria for evaluating wood wider range of products and services than at the Where economic return is quality, especially the narrow width of present. to valuable growth rings, are being reevaluated. Trees important, systems produce with larger diameters, clear boles and wid- crop trees will be needed. Integration of for will be er growth rings will be sought. In forests management multiple outputs managed for high-quality wood products, more important. Simultaneous consideration of economic benefits to either natural regeneration or seeding or aims, wildlife, planting at wider spacing will be used to aesthetics, recreation and soil and water lower costs. Efficient management will be protection will increase. New silvicultural will be as the uses of oak accomplished by several means, including systems required forests oak silviculture selection of a relatively small number of diversify. However, remains intensive and often crop trees and regulation of early stand de- very expen- sive. velopment to concentrate site potential on these trees to produce large stems and desirable form. Also thinning and greater mix- FUTURE RESEARCH ACTIVITIES ture of species in stands may become more important, as will site-related management decisions. The status of oak forests and trends in The trend is toward development of their management in Central Europe and more efficient methods for natural and arti- the United States as described in this se- ficial regeneration in Central Europe and ries of papers suggest 5 broad areas for the United States. There is evidence that additional research. These areas, with specific recommendations, follow. 1) Ecophy- low-cost systems for managing natural oak siology: determine the responses of sever- woodland communities for a variety of al important species to varying site and goods and services. This includes: i) sys- environmental conditions, including anthro- tems for a greater proportion of high- pogenic environmental changes and to valued wood on shorter rotations (< 100 treatments for establishing, tending and yr); ii) systems for natural stands of more thinning. 2) Growth and development: de- diverse species compositions for a greater termine the relationship between growth of combination of goods and services; iii) sys- trees of several species and crown struc- tems for integrated management where ture, stand structure (stocking and species multiple output is desired. 5) Oak decline: composition) and site quality. 3) Regener- determine the relation between oak decline ation: develop reliable natural regeneration and stand age and structure, species-site methods for stands of mixed composition interactions, and pollutants, insects and for a range of sites and environmental con- pathogens and their regulation by silvicul- ditions. 4) Silvicultural systems: develop tural treatment.