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Planted forests, although only seven per cent of the world's forest resources, have superseded naturally regenerating forests as the principal source of industrial wood products. Lessening the pressure for wood production, tree planting has released natural forests to be managed for other purposes - carbon sinks, soil and water protection, conservation of biological diversity, recreation and amenity. Representing a complement, but not an alternative, to natural forests, planted forests have become increasingly important for reducing worldwide deforestation, loss of forest ecosystems and forest degradation. Examining the significance of this rapidly emerging world resource, chapters consider the strengths and weaknesses of planted forests, management objectives for their use and aspects of ownership and policy. Data from key production countries are used to evaluate the implications and sustainability of planted forests as a source of forest products as well as social and ecological issues.

Forests cover approximately one-third of Central Europe. Oak (Quercus) and European beech (Fagus sylvatica,) are considered the natural dominants at low and middle elevations, respectively. Many coniferous forests (especially of Picea abies) occur primarily at midelevations, but these are thought to have resulted from forestry plantations planted over the past 200 years. Nature conservation and forestry policy seek to promote broadleaved trees over conifers. However, there are discrepancies between conservation guidelines (included in Natura 2000) and historical and palaeoecological data with regard to the distribution of conifers. Our aim was to bring new evidence to the debate on the conservation of conifers versus broadleaved trees at midelevations in Central Europe. We created a vegetation and land-cover model based on pollen data for a highland area of 11,300 km² in the Czech Republic and assessed tree species composition in the forests before the onset of modern forestry based on 18th-century archival sources. Conifers dominated the study region throughout the entire Holocene (approximately 40-60% of the area). Broadleaved trees were present in a much smaller area than envisaged by current ideas of natural vegetation. Rather than casting doubt on the principles of Central European nature conservation in general, our results highlight the necessity of detailed regional investigations and the importance of historical data in challenging established notions on the natural distribution of tree species. Aproximadamente un tercio de Europa Central esta cubierto por bosques. Encinos (Quercus) y hayas (Fagus sylvatica) son considerados los dominantes naturales en elevaciones bajas y medias, respectivamente. Muchos bosques de coniferas (especialmente Picea abies) ocurren como vegetación primaria en elevaciones medias, pero se piensa que resultaron de plantaciones forestales en los últimos 200 años. Las políticas de conservación de la naturaleza y forestales buscan promover árboles de hoja en lugar de coníferas. Sin embargo, hay discrepancias entre las directrices de conservación (incluidas en Natura 2000) y los datos históricos y paleoecológicos en relación con la distribución de coniferas. Nuestro objetivo fue aportar evidencias nuevas al debate sobre la conservación de coniferas versus árboles de hoja ancha en elevaciones medias en Europa Central. Creamos un modelo de vegetación y cobertura de suelo basado en datos de polen para tierras elevadas con superficie de 11,300 km² en la República Checa y evaluamos la composición de especies de árboles antes del desarrollo forestal moderno con base en fuentes en archivos del siglo 18. La zona de estudio (aproximadamente 40-60% de la superficie) fue dominada por coníferas durante el Holoceno. Árboles de hoja ancha estuvieron presentes en una superficie mucho menor que la considerada por las ideas actuales sobre la vegetación natural. En lugar de plantear dudas sobre los principios de la conservación de la naturaleza en general en Europa Central, nuestros resultados resaltan la necesidad de realizar investigaciones regionales detalladas así como la importancia de los datos históricos para cuestionar nociones establecidas sobre la distribución natural de especies de árboles.

Communities of xylotrophic fungi were studied in wood of Pinus mugo of different qualities: (i) living stems, (ii) cut stumps, (iii) burned snags, (iv) cut burned stumps, (v) stems recently killed by root rot, and (vi) old snags of root rot-killed trees. A total of 277 isolates representing 58 fungal taxa were obtained from 300 wood samples (50 samples per each substrate category). Results of the present study suggested that following different disturbances (tree felling, forest fire or root rot), fungal communities likely evolve in different directions: depending on its origin (cut, burned or killed by the disease), dead wood might be inhabited by principally different microbial assemblages, and that fire has less effect on community structures than tree felling or root rot.

This paper reviews the historical development of the use of the eucalypt over 200 years, from its curiosity status in the botanical gardens of Europe to its extensive use as a fuelwood for the wood-burning locomotives of the national railway systems, and then to its more recent use as a major source of biomass for paper pulp, fiberboard, industrial charcoal, and fuelwood. Ecological and biological aspects of the genus Eucalyptus have made it successful as an exotic in industrial monocultures and as a multipurpose tree of benefit to small landholders. Social, policy, and economic aspects of growing Eucalyptus are examined, as are prospects for using the eucalypt in the twenty-first century as an industrial plantation tree and as a component of farming systems in the rural landscape.

The abundance and distribution of natural populations can be strongly influenced by the types and arrangement of habitat patches within a landscape. The impact of landscape changes on population dynamics is difficult to study using conventional population models and field techniques. Spatially explicit simulation models provide a powerful method for modelling landscape and population changes at large spatial scales and may prove useful as a management tool for mobile animal populations. As an example of this approach, we present a model designed to elucidate the effects of landscape-level variation in habitat dispersion on the size and extinction probability of avian populations in a region managed for timber production. In the model, habitat suitability and availability within the landscape change annually as a function of timber harvest and management strategies. The model incorporates life history characteristics of Bachman's Sparrow (Aimophila aestivalis), a species of management concern in the southeastern United States, and the landscape characteristics of the Savannah River Site, South Carolina, an area managed for timber production where the sparrow is relatively common. Life history characteristics used in the model include dispersal, survivorship, and reproductive success information reported for Bachman's Sparrow at this site or elsewhere in its range. Results of the simulations suggest that variation in demographic variables affects population size more than variation in dispersal ability. Changes in adult and juvenile survivorship have especially large impacts on the probability of population extinction. The presence of habitat types that serve as permanent sources of dispersers increases the total population size in the landscape, and lowers the probability of extinction. Results of models such as BACHMAP can suggest modifications to current management plans that would increase the probability of population persistence for species of special concern in managed landscapes.

Ecologists have advocated retaining various densities of canopy trees in harvest units in Pacific Northwest forests. In contrast to clear-cutting, this practice may better emulate the patterns of disturbance and structural complexity typical of natural forests in the region. Several ecological attributes, including vertebrate habitat diversity, are thought to be associated with stands of complex structure. The goal of this study was to determine bird abundance in canopy retention sites relative to other common stand types in the Pacific Northwest and to develop habitat functions for extrapolating bird abundance across current and future landscapes. We used data from five previous studies in the west central Cascades of Oregon to compare bird abundance and to develop habitat functions for forest birds across a wide range of natural and managed stand structures and ages. The 67 stands included clearcuts, retention sites, young closed-canopy plantations, mature stands, and old-growth stands. ANOVA revealed that 18 of the 23 species included in the analysis differed significantly in abundance among the stand types, with some species being primarily associated with each of the stand types. The habitat variables used to build habitat functions included tree density by size class, mean tree diameter, and variation in tree diameter. Linear, polynomial, and various nonlinear regression models were evaluated for each bird species. Significant habitat functions were generated for 17 of the 23 bird species. The analyses identified four habitat-use guilds among the 17 bird species: open-canopy; open-canopy with dispersed large trees; structurally complex closed-canopy; and structurally simple closed-canopy guilds. This study is the first in the Pacific Northwest to compare bird abundances across natural stands, traditionally managed plantations, and stands managed under ecological forestry approaches. The results suggested that canopy tree retention benefits many, but not all, of the bird species we studied, Moreover, the nonlinear responses of bird abundance revealed thresholds in tree density at which bird abundance changed dramatically. Knowledge of these thresholds allow managers to design stands for specific biodiversity objectives. The habitat functions presented here can be used to predict bird abundance based on habitat measurements derived from field data, remotely sensed data, or output from computer models of forest dynamics.

We conducted breeding bird surveys in Minnesota, Wisconsin, and South Dakota in 12 hybrid popular plantations and surrounding landscapes from 1992 to 1994. Plantations varied in age, shape, composition of surrounding landscape, and internal vegetative heterogeneity. Numbers of breeding bird individuals and species in plantations were lower than in surrounding forest/shrub habitat, but higher than in row crops. Numbers of individuals observed within several bird groups based on migratory status and habitat preference also differed among plantations and surrounding land-use types. Most differences were between numbers in plantations and row crops. Year-to-year changes in bird species composition in plantations were more likely in plantations between ages 2 and 4 years than in younger or older plantations. Correlative evidence from canonical correspondence analysis illustrated that plantation bird communities were related to habitat in surrounding landscapes, plantation age, size, latitude, and longitude. Additionally, more heterogeneous plantations had more species, individuals, and numbers of long-distance migrants. Plantations will likely not support bird communities that are comparable to natural forests in either species composition or species diversity. A goal would be to position them in the landscape to minimize impacts on regional biodiversity. This could be accomplished by maintaining structural diversity of plantations by creating a broad range of successional stages (ages) throughout plantations within a region. Size and connectivity of existing forest fragments may be increased by plantations, but fragmentation of natural open areas should be avoided.

Loblolly pine (Pinus taeda L.) was a minor component of the vast natural forests of the southern United States before the region was settled by immigrants. Extensive planting and natural regeneration of cutover forest land and abandoned farmland between 1930 and 1990 made loblolly the leading timber species in the United States. It now predominates on 13.4 million ha (45 percent) of the commercial forest land in the southern United States (between latitudes 28 degrees N and 39 degrees N and longitudes 75 degrees W and 97 degrees W) and directly or indirectly provides 110,000 jobs and $30 billion to the economy of the region. The extreme versatility of loblolly has also provided important environmental contributions to most southern states. These include landscape beautification, erosion control, soil amelioration, excellent wildlife habitat, and outstanding recreational opportunities. Incorporating existing pest management strategies into silvicultural systems can produce substantial and long-lasting insect and disease control with little cost or physical effort. Introductions of loblolly into numerous countries around the world (especially China, Brazil, and Argentina) have proven to be very successful, environmentally sound, and commercially profitable. In some locations, loblolly grows much faster than on sites of similar quality in the southern United States.

A combination of superior wood quality and high productivity has made Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) one of the premier timber trees in the world. As such, it is grown as a plantation species in several countries in Europe, South America, New Zealand, and Australia, as well as throughout its extensive natural range in western North America. Decades of experience with the silviculture of young stands have demonstrated that practices such as planting, the use of genetically improved seedlings, precommercial and commercial thinning, and fertilization may dramatically increase the yield of industrial products over that of natural forests. Further, such silviculture is compatible with the production of desired amenities. Vigorous implementation of such practices wherever Douglas-fir is cultivated will increase the world's timber resources, and be an effective strategy for reducing the pressure, occasioned by the world's rapidly increasing population, to harvest the fragile tropical and boreal forests.[PUBLICATION ABSTRACT]

New silivicultural strategies to sustain both ecological and human communities are being developed and implemented on federal forest lands in the Pacific Northwest (PNW) United States. Two important stand-level components of the new silviculture regimes are rotation age and retention level of live trees in harvest units. Ecologists have suggested that canopy tree retention and longer rotations will create patterns of stand structure in managed forest that are similar to those in natural forests, and promote long-term ecological productivity and biodiversity. Forest economists, however, are concerned that canopy tree retention and long rotations may reduce wood production, although the high value of large logs produced by these new silvicultural regime may compensate for reduced growth rates. We used the forest model ZELIG to perform a factorial simulation experiment on long-term responses of ecological and economic variables to nine retention levels and four rotation lengths. ZELIG output on forest structure and composition was input to a forest economics model that calculated net value of wood products in 1989 dollars. The simulated stand data were also linked with regression equations to predict the densities of 17 bird species as a function of tree size class distribution. Five replicates of each treatment were run for the 240-yr simulation period. Results indicated that stand structure under each of the canopy tree retention levels was more similar to the pre-treatment natural forest than following clear-cutting. Variation in tree size under intermediate levels of retention, however, did not reach the level of the natural forest during the simulation period. Tree species composition was strongly related to retention level and rotation age. Shade-intolerant Douglas-fir (Pseudotsuga menziesii) lost dominance to shade-tolerant species under intermediate retention levels and longer rotations. Wood production decreased significantly with increasing retention level and rotation age, with a notable threshold between retention levels of 0 and 5 trees per hectare. Net wood products value did not decrease as rapidly with retention level, and did not differ much among rotation ages, because of the high value of large logs. Bird species responded individualistically to retention level and rotation age. Some had peak densities under short-rotation clear-cutting, but most were associated with structurally complex, closed-canopy forest. Consequently, bird species richness increased significantly with retention level and rotation age. Within the assumptions and limitations of our models, this application provided knowledge on trends and thresholds that can help land managers to choose silvicultural regimes that best balance their management objectives. We concluded that retention level and rotation age strongly influence ecological and economic responses in PNW forests; efforts are needed to reduce uncertainty about these effects.