Showing papers in "Forestry in 2010"
TL;DR: A list of published scientifi c articles on growth modelling is provided and is grouped according to the different types of model in this article, where the current practices and silvicultural recommendations, based on research directed at high-quality timber production in silver birch stands, are reviewed.
Abstract: Summary In Europe, two commercially important treelike birch species occur naturally: silver birch ( Betula pendula Roth) and downy birch ( Betula pubescens Ehrh.). Both species have a wide natural distribution area on the Eurasian continent, ranging from the Atlantic to eastern Siberia. Although birches occur throughout almost the whole of Europe, the most abundant birch resources are in the temperate and boreal forests of Northern Europe. In the Baltic and Nordic countries, the proportion of birch out of the total volume of the growing stock varies between 11 and 28 per cent. In Northern Europe, birch is commercially the most important broadleaved tree species. Birches are light-demanding early successional pioneer species, which grow both in mixed stands and in pure stands. This article provides an overview of the most important ecological characteristics and typical growth and yield patterns of birch, based on European scientifi c literature. Growth and yield research on birch has been relatively active in Northern Europe, where numerous growth and yield models have been developed during the last decades. In this paper, a list of published scientifi c articles on growth modelling is provided and is grouped according to the different types of model. When growing in forest stands, birches have a relatively straight slender stem form. The current practices and silvicultural recommendations, based on research directed at high-quality timber production in silver birch stands, are reviewed. Although the emphasis is on even-aged pure silver birch stands, the management of mixed stands as well as the silviculture of downy birch and curly birch are also briefl y discussed.
287 citations
TL;DR: In the majority of modern forest management systems, mature trees are harvested above the root collar, leaving stumps in the ground as discussed by the authors, and the potential for utilizing stump biomass as an additional source of renewable fuel is explored.
Abstract: In the majority of modern forest management systems, mature trees are harvested above the root collar, leaving stumps in the ground. Due to widespread concern about climatic change caused by anthropogenic emissions of greenhouse gases, increasing prices of fossil fuels and a desire to improve energy security, there is a growing interest in the exploitation of alternative sources of energy, including forest biomass ( Bjorheden, 2006 ). Commercial operations are now effectively utilizing the entire above-ground tree biomass to produce both timber and fuel ( Hakkila, 1989 ). A more recent development is interest in the potential for utilizing stump biomass as an additional source of renewable fuel ( Hakkila and Aarniala, 2004 ). Historically, stumps were harvested both for fuel and for other uses including providing material for the horns of sledges, knee timber in ships and boats and ploughs ( Gayer, 1896 ). Stump wood was also used in Sweden for the production of tar between 1850 and 1950 ( Karlsson, 2007 ). Declining demand for woodfuel coupled with the industrial production of alternative materials such as steel led to reduced requirements for stump wood in central Europe towards the end of the nineteenth century. Driven by concerns about a looming fi bre crisis (associated with a shortfall forecast in small roundwood supplies) as well as the oil crisis (associated with increasing concerns about energy security) stump harvesting became the focus of a research programme in Scandinavia in the 1970s ( Hakkila, 2004 ; Bjorheden, 2006 ; Egnell et al. , 2007 ). The predicted fi bre crisis failed to materialize, while the cost of stump harvesting proved to be excessive ( Hakkila, 2004 ) and commercial stump harvesting for fi bre and fuel production was largely abandoned. Since then demand for other forest fuels has continued to grow, leading to a re-evaluation of the potential of stumps as an energy source. Karjalainen et al. (2004) estimated that across Europe, there is the potential to source up to 9 million m 3 year 1 of forest chips from stumps per annum, out of a total potential annual increment of 78 million m 3 year 1 . One hectare can produce upwards of an additional 100 m 3 of woodfuel, equivalent to 100 MWh ha 1 ( Flynn and Kumar, 2005 ), with some reports of 200 MWh ha 1 ( Hakkila and Aarniala, 2004 ) and 250 MWh ha 1 (Rolfsson, 2006 , cited in Eriksson and Gustavsson, 2008 : 897). The biomass available from the stump – root system offers the potential to gain an additional 20 per cent beyond that obtainable from the stem ( Richardson et al. , 2002 ). Stump Harvesting for Bioenergy – A Review of the Environmental Impacts
258 citations
TL;DR: In this article, a mixed temperate forest landscape in southwestern Germany, multiple remote sensing variables from aerial orthoimages, Thematic Mapper data and small footprint light detection and ranging (LiDAR) were used for plot-level nonparametric predictions of the total volume and biomass using three distance measures of Euclidean, Mahalanobis and Most Similar Neighbors as well as a regression tree-based classifier (Random Forest).
Abstract: Summary In a mixed temperate forest landscape in southwestern Germany, multiple remote sensing variables from aerial orthoimages, Thematic Mapper data and small footprint light detection and ranging (LiDAR) were used for plot-level nonparametric predictions of the total volume and biomass using three distance measures of Euclidean, Mahalanobis and Most Similar Neighbour as well as a regression tree-based classifier (Random Forest). The performances of nearest neighbour (NN) approaches were examined by means of relative bias and root mean squared error. The original highdimensional dataset was pruned using an evolutionary genetic algorithm search with a NN classification scenario, as well as by a stepwise selection. The genetic algorithm (GA)-selected variables showed improved performance when applying Euclidean and Mahalanobis distances for predictions, whereas the Most Similar Neighbour and Random Forests worked more precise with the full dataset. The GA search proved to be unstable in multiple runs because of intercorrelations among the high-dimensional predictors. The selected datasets are dominated by LiDAR height metrics. Furthermore, The LiDAR-based metrics showed major relevance in predicting both response variables examined here. The Random Forest proved to be superior to the other examined NN methods, which was eventually used for a wallto-wall mapping of predictions on a grid of 20 × 20 m spatial resolution.
202 citations
TL;DR: Climate change is very likely to enhance the suitability of the authors' climate for a range of non-native pests and pathogens, many of which are brought in unknowingly on infected planting stock sourced for new greening schemes.
Abstract: Summary The predicted change in our climate is likely to inflict particular stresses on the trees and other plants constituting urban and peri-urban greening schemes, and this may increase their susceptibility to certain pests and diseases. This review highlights the various ways in which climate change may affect the health of urban trees in Britain. In summary, climate change may alter patterns of disturbance from pathogens and herbivorous insects through physiological changes in the host plant. The expected changes in temperature and moisture availability will also directly affect the development and survival of the pests and pathogens, and their natural enemies, competitors and vectors. This may alter the impact of native pests and diseases and increase the populations of some species not currently recognized as pests to epidemic proportions. Perhaps most significantly, climate change is very likely to enhance the suitability of our climate for a range of non-native pests and pathogens, many of which are brought in unknowingly on infected planting stock sourced for new greening schemes. The global trade in ‘plants for planting’ is a recognized pathway for the accidental introduction of pests and pathogens even though plant health legislation exists to minimize such accidental
186 citations
TL;DR: Black alder is a scattered, widespread and short-lived species that thrives in low-lying damp and riparian places and has a use in flood control, stabilization of riverbanks and in functioning of the river ecosystems.
Abstract: Summary Black alder is a scattered, widespread and short-lived species that thrives in low-lying damp and riparian places. It has a use in flood control, stabilization of riverbanks and in functioning of the river ecosystems. To thrive, precipitation must exceed 1500 mm if access to groundwater is not possible. Alders are unusual among European trees in that they fix nitrogen. To regenerate naturally, alder requires high levels of both light and moisture, usually achievable only on disturbed sites. Growth rates up to ages 7–10 are very fast but then slow rapidly. Sixty to seventy years is the maximum rotation for growing timber if heart rot is to be avoided. Maximum mean annual increments range from 4 to 14 m 3 ha 21 year 21 . Alder wood is used for energy, as fibre for paper and particle board and, most profitably, in joinery as solid wood or veneer. Logs must be at least 3 m long and ideally 50–60 cm diameter. Aspects of plantation silviculture are discussed with emphasis on thinning, which needs to be started early and to be heavy and frequent around selected final crop trees to achieve marketable timber before heart rot sets in.
161 citations
TL;DR: In this article, the authors optimized the steady-state structure and management of uneven-sized Scots pine and Norway spruce stands, so as to help develop management instructions, and the post-thinning diameter distribution was optimized with 20-year cutting cycle when aiming at maximal economic profitability.
Abstract: Summary In Finland, uneven-sized forest management is gradually becoming an acceptable practice At the moment, there are no silvicultural instructions for the management of uneven-sized forests, although there is willingness among forest owners to adopt this practice This study optimized the steady-state structure and management of uneven-sized Scots pine and Norway spruce stands, so as to help develop management instructions The post-thinning diameter distribution of the uneven-sized stand was optimized with 20-year cutting cycle when aiming at maximal economic profitability Spruce stand optimizations were done for fertile and medium sites and pine stand optimizations for medium and poor sites The optimal post-thinning distributions had a truncated reverse J shape, the frequencies of all trees larger than 18–20 cm being zero This shape means that all log-sized trees have to be removed at 20-year intervals when economic profitability is maximized When sawlog production was maximized, the largest retained trees were 25–30 cm in diameter at breast height (dbh) The optimal diameter distributions of pine stands were clearly more uniform than spruce distributions, ie the preponderance of small trees was less pronounced in pine With 2 per cent discounting rate, the optimal post-thinning basal area of trees larger than 5 cm dbh was 11–12 m 2 ha 21 for fertile spruce stands and 4–9 m 2 ha 21 for pine stands and spruce stands of medium fertility Uneven-sized management was found to be more profitable than even-aged management; even-aged management was more profitable only in spruce stands on fertile sites in southern Finland with low discounting rate (1 per cent) Increasing discounting rate and decreasing site productivity improved the relative performance of uneven-sized management
88 citations
TL;DR: Scattered broadleaved tree species such as ashes, black alder, wild service tree, wild cherry and wild cherry are important components of European forests and are likely to have less ability to reproduce or adapt to shifting climate space than more widespread species.
Abstract: Summary Scattered broadleaved tree species such as ashes ( Fraxinus excelsior L. and Fraxinus angustifolia Vahl.), black alder ( Alnus glutinosa (L.) Gaertn.), birches ( Betula pendula Roth. and Betula pubescens Ehrh.), elms ( Ulmus glabra Huds., Ulmus laevis Pall. and Ulmus minor Mill.), limes ( Tilia cordata Mill. and Tilia platyphyllos Scop.), maples ( Acer campestre L., Acer platanoides L. and Acer pseudoplatanus L.), wild service tree ( Sorbus domestica L. and Sorbus torminalis L. Crantz), walnuts ( Juglans regia L., Juglans nigra L. and hybrids) and wild cherry ( Prunus avium L.) are important components of European forests. Many species have high economic, environmental and social values. Their scattered distributions, exacerbated in many cases by human activity, may make them more vulnerable to climate change. They are likely to have less ability to reproduce or adapt to shifting climate space than more widespread species. The general impacts of climate change on these scattered species are reviewed. Some specifi c risks and opportunities are highlighted for each species, although there is considerable uncertainty and therefore, diffi culty in quantifying many specifi c risks and/or impacts on scattered broadleaved tree species.
77 citations
TL;DR: Seedling density declined most sharply at relatively low deer densities, indicating that advanced regeneration is particularly sensitive to deer presence and that regeneration is most likely to be inadequate at densities above 14 deer km 2.
Abstract: Summary Relatively little information is available to indicate how the impacts of deer vary in relation to densities of deer encountered in lowland environments in Britain. Population densities and impacts of deer on advance regeneration were therefore assessed at 15 sites, embracing a range of densities from 0 to 54.9 deer km 2 in woodland and 0 – 74.5 km 2 in adjacent fi elds. Deer densities tended to be higher on sites with drier and more fertile soils, a relationship which may have arisen for either nutritional or management reasons. The log seedling density was negatively correlated with deer density, relative use of woodland vs adjacent fi elds and deer species (expressed as a proportion of ‘ larger ’ species, mainly Fallow deer Dama dama ). The abundance of smallest seedlings (<30 cm tall) was also correlated with soil moisture content and tree canopy cover; however, these effects were not signifi cant for larger seedlings (30 – 150 cm tall), which were instead associated primarily with deer variables. Seedling density declined most sharply at relatively low deer densities, indicating that advanced regeneration is particularly sensitive to deer presence. The results indicate that regeneration is most likely to be inadequate at densities above 14 deer km 2 .
76 citations
TL;DR: In this article, the authors quantify aboveground and belowground biomass and respective carbon storage in temperate forests landscape in Cofre de Perote, Veracruz, Mexico.
Abstract: Summary Temperate forests play a significant role in the global carbon cycle. However, deforestation, land use changes and differences in successional and species composition cause a spatial heterogeneity in the potential carbon storage in the landscape. The aims of this study were (1) to quantify aboveground and belowground biomass and respective carbon storage and (2) to project the future carbon storage in temperate forests landscape in Cofre de Perote, Veracruz, Mexico. Aboveground and belowground biomass was estimated in seven forests with different species composition and conservation status and management, in three grasslands and in two shrublands at a range of altitudes. Total biomass in forests ranged from 91.07 to 383.78 Mg ha 21 , in grassland from 9.83 to 24.93 Mg ha− 1 and in successional (shrublands) from 6.33 to 7.69 Mg ha− 1 . This suggests that deforestation and changes of land use could reduce aboveground biomass by 90 per cent. Mature forests had the largest aboveground and belowground biomass and the lowest density (number of trees per hectare) but a lower potential for accumulation of C in the future; in contrast, young forests and reforested areas had higher growth and carbon storage potential. Our results suggest that avoiding deforestation and improving forest management could play a major role in global climate change mitigation.
70 citations
TL;DR: The main conclusion of this review is that transformation to continuous cover forestry will not lead to a reduction or improvement in the quality of timber being produced in forests in the UK, and the main effect will probably be to increase the variation of log sizes and wood properties that are available in the market.
Abstract: Summary There is an increasing move in the UK to transform even-aged, single-species conifer plantations to continuous cover forest, i.e. more diverse and irregular stand structures. However, experience of doing this is limited and research to date has not addressed the consequences of this change on timber quality. This paper reviews the impact of transformation on timber quality and wood properties and uses coupled growth and timber property model simulations to examine the effects of different transformation scenarios on Sitka spruce ( Picea sitchensis (Bong.) Carr.). The results of the modelling broadly confi rmed the conclusions from the literature review. Five key aspects of transformation are considered. Retaining trees to older ages can produce higher quality timber with improved mechanical properties. Regular selective thinning and increased use of crown thinning will improve timber quality, but timing is critical to avoid producing highly tapered trees with heavy branches. Creating gaps in a uniform canopy will generally have a negative impact on the timber quality of the trees around the gap edges. Increased variation in tree age, size, spacing and species will result in greater variation in log quality and wood properties. Using natural regeneration reduces the opportunities for improved growth and timber quality offered by selectively bred planting stock but can deliver good-quality timber if the characteristics of the original stand are suitable and adequate stocking is achieved. The main conclusion of this review is that transformation to continuous cover forestry will not lead to a signifi cant reduction or improvement in the quality of timber being produced in forests in the UK. The main effect will probably be to increase the variation of log sizes and wood properties that are available in the market.
69 citations
TL;DR: In this paper, the potential impact of compositional and structural diversity on forest productivity was examined using data from 1500 ponderosa pine stands in the western United States, where relative density, height, and site quality were combined in a conceptually sound expression of the relationship between growth and growing stock for pine dominated stands of relatively simple structure.
Abstract: Summary Data from ~ 1500 ponderosa pine ( Pinus ponderosa C. Lawson) stands in the western United States were used to examine the potential infl uence of compositional and structural diversity on forest productivity. Relative density, height and site quality were combined in a conceptually sound expression of the relationship between growth and growing stock for ponderosa pine-dominated stands of relatively simple structure. Predictions from this model were compared with productivity of more compositionally and structurally diverse stands. Our results are consistent with the common observation in forest production ecology that stand growth is not strongly infl uenced by either compositional or structural diversity.
TL;DR: In this paper, the most common form of forest stand parameter estimation is undertaken based on field-based forest inventory data, with measurements collected using sampling frames, which tend to be sparsely distributed when inventories are carried out across a country (e.g. national forest inventories) or region.
Abstract: The most common form of forest stand parameter estimation is undertaken based on field-based forest inventory data. Parameter estimations are implemented at a range of scales depending on the user needs and requirements. Due to time and cost constraints, these approaches are sample based, with measurements collected using sampling frames, which tend to be sparsely distributed when inventories are carried out across a country (e.g. national forest inventories) or region (Matthews and Mackie, 2006). Commonly, forest managers require detailed information on individual stands in order to plan silvicultural management strategies. Such information is typically derived from a stand-based inventory, where detailed measurements from several plots are collected within each stand, providing more precise forest parameter estimates. In recent decades, forest practitioners have increasingly integrated remote sensing data as a means of assisting and complementing forest inventories. Aerial photography has been used extensively to estimate forest attributes, which include species identification, tree height, crown diameter and the delineation of forest boundaries (Tuominen and Pekkarinen, 2005). Top height is an important forest parameter that is used in the UK and Ireland to estimate Yield Class (annual production potential) and as an indicator of standing biomass. Using remote sensing, tree height can be measured using high-resolution stereoscopic aerial photos, with photogrammetric techniques to measure the lengths of shadows projected onto level open ground (Kovats, 1997). However, these techniques are dependent on a number of factors that include level open ground and the need to determine the sun elevation and latitude, which consequently limits the operational use of these techniques. However, a more effective approach to determine tree heights in forests is by using parallax measurements from stereoscopic photographs (Schut and Van Wijk, 1965). More recently, research has been conducted that combines space-borne satellite imagery with forest inventory Forest canopy height retrieval using LiDAR data, medium-resolution satellite imagery and kNN estimation in Aberfoyle, Scotland
TL;DR: In this article, different methods were used to predict mean crown height of Norway spruce-dominated stands by means of low pulse density airborne laser scanning (ALS) data, and the results obtained were partly contradictory, showing varying performance of different methods using different datasets.
Abstract: Summary In this study, different methods were used to predict mean crown height of Norway spruce-dominated stands by means of low pulse density airborne laser scanning (ALS) data. The methods were based on statistical modelling, properties of the laser point clouds or combinations of them. Separate modelling data were used for model calibration and two different validation datasets were used to assess the accuracy of the results. The results obtained were partly contradictory, showing varying performance of different methods using different datasets. However, there were also notable differences between the methods used to obtain crown height by field measurements. The root mean square error figures of crown height predictions were at minimum between 1.0 and 1.5 m. This study showed that statistical modelling based on ALS height metrics was a good approach if the relationship between mean crown height and the ALS information was corresponding in the modelling data and in the application phase. A method based on the alpha shape technique was also an accurate alternative. Methods that rely directly on the laser point cloud to predict mean crown height without any calibration were good alternatives to get relatively accurate results but there are still drawbacks (area of calculation unit) in their applicability.
TL;DR: In this article, fine root dynamics and net primary production were studied using the sequential soil coring method in an old-growth Korean pine (Pinus koraiensis Sieb.et Zucc.) mixed broadleaved forest, an 80-year old stand of secondary birch (Betula platyphylla Suks.) in mixture with poplar (Populus davidiana Dode).
Abstract: Summary Fine root dynamics and net primary production were studied using the sequential soil coring method in an old-growth Korean pine (Pinus koraiensis Sieb.et Zucc.) mixed broadleaved forest, an 80-year-old stand of secondary birch (Betula platyphylla Suks.) in mixture with poplar (Populus davidiana Dode) and a 20-year-old stand of secondary birch and poplar in Changbai Mountains in Northeast China. The biomass and necromass of the fine roots in the 0- to 0.5-m soil layer were determined every month from May to October in three types of forest during 2002. The total and monthly production dynamics of the fine roots were calculated and analysed according to seasonal biomass changes along the successional gradient, as well as their carbon and nitrogen contents. The total production of the fine roots from the dominant tree species increased along the successional gradient, being 222.8, 569.1 and 672.3 g m 22 from the young forest through to the old-growth stage, respectively. As important soil carbon and nitrogen sources, the total carbon and nitrogen storages by fine root growth increased along forest succession in the Changbai Mountains.
TL;DR: In this article, the authors examined density-size relationships for Sitka spruce (Picea sitchensis) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) using data collected in stands in Great Britain (GB) and Western Canada.
Abstract: Summary In this study, we examined density–size relationships for Sitka spruce (Picea sitchensis (Bong.) Carr.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) using data collected in stands in Great Britain (GB) and Western Canada. These two conifers are native to Western North America and have been widely planted in GB. Results indicate differences between stands in Canada and GB in both the intercept and slope of the log maximum density–log size boundary lines. In GB, the slope (b) of the relationship between log of stand density (number of trees per hectare) and log of quadratic mean diameter (Dq) is steeper than the theoretical value of −1.605 (−2.063 for Sitka spruce and −1.864 for Douglas-fir). Values of b are lower in Canada (−1.437 for Sitka spruce and −1.241 for Douglas-fir) than in GB . Within each region, b is similar for the two species. However, the intercept term differs for Sitka spruce and Douglas-fir in GB. These differences provide additional evidence that density–size boundary line relationships are influenced by environmental and other factors and indicate the need for development of density–size relationships for each species and for each region where the species is grown. Maximum stand density index (SDI) values calculated using these relationships are 1868 and 2073 for Sitka spruce and 1491 and 1815 for Douglas-fir in GB and Canada, respectively. Differences in maximum SDI between these two regions may be related to differences in climate, provenance, stand history and other factors. Maximum density–size relationships presented in this paper can be used as a starting point for managing stand density for both even-aged and continuous cover stands and for identifying potential maximum stocking in stands of these species in GB and Canada.
TL;DR: In this paper, the authors present evidence of widespread changes in structure and species composition between the 1980s and 2003-2004 from surveys of 249 British broadleaved woodlands, including canopy cover, vertical vegetation profiles, field-layer cover and deadwood abundance.
Abstract: Evidence is presented of widespread changes in structure and species composition between the 1980s and 2003–2004 from surveys of 249 British broadleaved woodlands. Structural components examined include canopy cover, vertical vegetation profiles, field-layer cover and deadwood abundance. Woods were located in 13 geographical localities and the patterns of change were examined for each locality as well as across all woods. Changes were not uniform throughout the localities; overall, there were significant decreases in canopy cover and increases in sub-canopy (2–10 m) cover. Changes in 0.5–2 m vegetation cover showed strong geographic patterns, increasing in western localities, but declining or showing no change in eastern localities. There were significant increases in canopy ash Fraxinus excelsior and decreases in oak Quercus robur/petraea. Shrub layer ash and honeysuckle Lonicera periclymenum increased while birch Betula spp. hawthorn Crataegus monogyna and hazel Corylus avellana declined. Within the field layer, both bracken Pteridium aquilinum and herbs increased. Overall, deadwood generally increased. Changes were consistent with reductions in active woodland management and changes in grazing and browsing pressure. These findings have important implications for sustainable active management of British broadleaved woodlands to meet silvicultural and biodiversity objectives.
TL;DR: Bramble reduced the incidence of browsing, an effect which appeared to be due to its relationship with seedling size, indicating that bramble facilitates the establishment of both willow and birch in a beech woodland.
Abstract: Summary Bramble is a prickly shrub that may facilitate the establishment of tree seedlings at sites where grazing animals are present, but its role in forest regeneration is less clear. This study took place in a beech woodland over the 5-year period immediately after a heavy thinning to leave a basal area of 6.5 m 2 ha 1 . Development of the ground fl ora and the growth and browsing of birch and willow seedlings were observed annually at the end of the summer. The ground fl ora became dominated by a dense thicket of bramble c . 60 cm tall. The tree species differed in their susceptibility to browsing with a greater percentage of willow being browsed than birch. Similarly, willow seedling mortality was greater. Over the 5-year period, the average height of birch reached c . 2 m compared with c. 0.6 m for willow. For both species, there were signifi cant positive relationships between seedling height and diameter and bramble cover and heights indicating that bramble facilitates the establishment of both willow and birch. Bramble reduced the incidence of browsing, an effect which appeared to be due to its relationship with seedling size. The potential role of bramble in the facilitation of naturally regenerating tree seedlings within woodlands is discussed.
TL;DR: Pretzsch et al. as mentioned in this paper proposed a new definition of sustainability in forestry which goes far beyond the traditional focus on wood volume that guided forestry in Central Europe so far (MCPFE, 1993; MCPFE 2003a, 2003b; Hasenauer, 2004; Baumgarten and von Teuffel, 2005).
Abstract: The responsibilities of modern forest practice and science in Central Europe have changed strongly within the last decades. The awareness of anthropogenic causes for the forest decline in the 1980s and for the rapid climate change has led to a new definition of sustainability in forestry which goes far beyond the traditional focus on wood volume that guided forestry in Central Europe so far (MCPFE, 1993; MCPFE, 2003a, 2003b; Hasenauer, 2004; Baumgarten and von Teuffel, 2005). One of the ‘hot’ topics of the sustainability criteria is the forest carbon budget. On global scale, the forest carbon mitigation potential is estimated to reach 0.35–1.15 Gt C year‐1 in 2030 (IPCC, 2007), which can contribute to buffer the still increasing anthropogenic CO2 emission (9.5–13.5 Gt C year‐1 in 2030; IPCC, 2007). For Germany, the second national forest inventory in 2003 (BMVEL, 2005) revealed an average volume density of 320 m3 ha‐1 (~120 t C/ha; calculation according to Baritz and Strich, 2000), and an increase in standing volume of ~20 per cent compared with the first national inventory in 1990 (only comparing values of former West Germany). Of course, the potential carbon density is limited and will certainly alter under changing climate conditions. Until the end of the 21st century, mean annual temperature in Germany will rise by 1.4–2.1°C combined with changes in precipitation of −10 to +10 per cent (SRES B1 according to Spekat et al., 2007). Along with the climate, other environmental conditions such as soil properties or immission concentrations will also change. The influence of these single and combined effects, as well as feedback reactions on the growth of trees and forest stands is not yet understood in detail, although there are a lot of studies dealing with these topics (e.g. Pretzsch and Dursky, 2002; Bergh et al., 2003; Rötzer et al., 2005; Garcia-Gonzalo et al., 2007). Forest growth models integrate a wide range of system knowledge and can calculate scenarios under different management regimes (Pretzsch et al., 2008). Reviews of these models, their use and possible fields of application can be found in Battaglia and Sands (1998), Bugmann (2001), Le Roux et al. (2001), Porte and Bartelink (2002), Monserud (2003) or Pretzsch et al. (2008). Most directly, however, the carbon sequestration potential of forests is dependent on forest management in terms of species choice and stand density regulation as well as on disturbances. As such factors cannot be tested in realtime scenarios, forest growth models are needed that predict stand development and differentiation in dependence Productivity and carbon dynamics in managed Central European forests depending on site conditions and thinning regimes
TL;DR: The objectives of this paper are to examine the design, implementation and monitoring of the process of transformation and to investigate if the data collected can be used to quantify the progress of transformation to an irregular structure.
Abstract: Summary The main aim of the Glentress Trial Area has been to study the transformation of even-aged plantations to a permanently irregular structure using group selection. The Trial Area was established in 1952 when most of the plantations were 20-30 years old. The 117-ha area was divided into six Blocks and the plan was to transform the area over a 60-year period by felling and regenerating groups totalling 2 ha in each Block every 6 years. The objectives of this paper are (1) to examine the design, implementation and monitoring of the process of transformation and (2) to investigate if the data collected can be used to quantify the progress of transformation to an irregular structure. The Trial Area has been driven by a clear objective but unfortunately the management plan has not been revised and there has not been a consistent approach to record keeping. This has made it difficult to relate management interventions to the development of the forest structure. An earlier analysis claimed that transformation was almost complete; this was based on a comparison of diameter distributions of the 1990 data with an exponential regression. However, the analysis in this paper includes all the data collected between 1952 and 1990 and shows that the diameter distribution of all Blocks has been similar to an exponential since the start of the Trial. The main reason for this is that the monitoring unit has been the Block, and a spatial scale of ~20 hectares is probably too coarse to detect the changes that are clear in aerial photographs.
TL;DR: The Top Ten Questions for Forestry (T10Q) project as discussed by the authors investigated a process for compiling and prioritizing a meaningful set of research questions, which were considered by participating stakeholders to have high policy relevance, using a collaborative bottom-up approach involving professionals from a wide set of disciplines of relevance to modern forestry.
Abstract: There is growing interest in widening public participation in research and practice in environmental decision making and an awareness of the importance of framing research questions that reflect the needs of policy and practice. The Top Ten Questions for Forestry (T10Q) project was undertaken in 2008 to investigate a process for compiling and prioritizing a meaningful set of research questions, which were considered by participating stakeholders to have high policy relevance, using a collaborative bottom-up approach involving professionals from a wide set of disciplines of relevance to modern forestry. Details are presented of the process, which involved an online survey and a workshop for participants in the UK and Republic of Ireland. Survey responses were received from 481 researchers, policy makers and woodland owners, who contributed 1594 research questions. These were debated and prioritized by 51 people attending the workshop. The project engaged people who were outside the traditional boundaries of the discipline, a trend likely to be more important in the future, particularly in the light of complex problems connected with climate change, bioenergy production or health and well-being, for example, which require multidisciplinary partnerships within the research and policy communities. The project demonstrated the potential for combining web-based methods and focussed group discussions to collect, debate and prioritize a large number of researchable questions considered of importance to a broad spectrum of people with an active interest in natural resource management.
TL;DR: In this paper, the authors explored the opportunity costs of restricting silvicultural options by comparing a natural pine regime to plantation management regimes with and without herbicide using some basic economic criteria.
Abstract: Summary Forest certification is designed to assure consumers that the wood products they purchase come from sustainably managed forests. Certified forests must meet certain standards that vary with the certification scheme. However, certification generally promotes environmental objectives by restricting forest management options in ways that may reduce wood and fibre production and increase the cost of delivering wood to market. For example, some aspects of certification programmes can discourage creation of new forest plantations and application of herbicide and fertilizer. These restrictions have costs which often are difficult to quantify. Bounds on the opportunity costs of restricting silvicultural options are explored by comparing a natural pine regime to plantation management regimes with and without herbicide using some basic economic criteria. In this analysis, a plantation regime with herbicide had nearly four times the land expectation value ( le V) of a natural pine regime and almost double the le V of a plantation without herbicide treatment.
TL;DR: In this paper, the authors measured the effects of post-fire logging in a Mediterranean-climate mixed-conifer forest in southwest Oregon, USA and found that dead tree removal was associated with lower nightly minimum temperatures and earlier daytime heating, leading to a 1-2°C difference during the warming portion of the day.
Abstract: Summary Following stand-replacing wildfire, post-fire (salvage) logging of fire-killed trees is a widely implemented management practice in many forest types. A common hypothesis is that removal of fire-killed trees increases surface temperatures due to loss of shade and increased solar radiation, thereby influencing vegetation establishment and possibly stand development. Six years after a wildfire in a Mediterranean-climate mixed-conifer forest in southwest Oregon, USA, we measured the effects of post-fire logging (>90 per cent dead tree (snag) removal) on growing season surface air temperatures. Compared with unlogged severely burned forest, post-fire logging did not lead to increased maximum daily surface air temperature. However, dead tree removal was associated with lower nightly minimum temperatures (~1°C) and earlier daytime heating, leading to a 1–2°C difference during the warming portion of the day. Effects varied predictably by aspect. The patterns reported here represent a similar but muted pattern as previously reported for microclimatic changes following clear-cutting of green trees. Effects of microsites such as tree bases on fine-scale temperature regimes require further investigation.
TL;DR: Age was found to be the principal factor affecting the ring shake defect, the incidence of which was highest in trees aged 30 years or over, and the highest risk of splitting occurred in the 12- to 14-year-old age group, although cracking started with a certain intensity at an age of 7–8 years.
Abstract: Summary The incidence of ring shake in chestnut wood (Castanea sativa Mill.) from eight sites (237 total trees) in the Lazio territory, in central Italy, was investigated. All the areas studied are coppice managed. The aim of this study was to increase knowledge of this defect through the measurement and classification of numerous indices. using analysis of variance and correlation analysis, age was found to be the principal factor affecting the ring shake defect, the incidence of which was highest in trees aged 30 years or over. The highest risk of splitting occurred in the 12- to 14-year-old age group, although cracking started with a certain intensity at an age of 7–8 years. Comparing trees of the same age (25–30), it can be seen that diameter was not strongly related to magnitude of defect, but it had the effect of moving the ring shake location outwards. Wood defects (star shake, injuries, double core and eccentricity of core) and stem defects (cortical cancer, epicormic branches, dead branches and bark cracking) were not significantly correlated with shake: indeed, only bark cracking and injuries seem to have a slight influence on ring shake risk.
TL;DR: Systematic, range-wide common environment trials can provide insights into the evolution of the native pinewoods, indicating how environment has influenced phenotypic variation and how variation is maintained.
Abstract: Summary Scots pine (Pinus sylvestris L.) is a foundation species in Scottish highland forests and a national icon. Due to heavy exploitation, the current native pinewood coverage represents a small fraction of the postglacial maximum. To reverse this decline, various schemes have been initiated to promote planting of new and expansion of old pinewoods. This includes the designation of seed zones for control of the remaining genetic resources. The zoning was based mainly on biochemical similarity among pinewoods but, by definition, neutral molecular markers do not reflect local phenotypic adaptation. Environmental variation within Scotland is substantial and it is not yet clear to what extent this has shaped patterns of adaptive differentiation among Scottish populations. Systematic, range-wide common environment trials can provide insights into the evolution of the native pinewoods, indicating how environment has influenced phenotypic variation and how variation is maintained. Careful design of such experiments can also provide data on the history and connectivity among populations, by molecular marker analysis. Together, phenotypic and molecular datasets from such trials can provide a robust basis for refining seed transfer guidelines for Scots pine in Scotland and should form the scientific basis for conservation action on this nationally important habitat.
TL;DR: A simulation model was devised to describe the behaviour of disease caused by H. annosum in Sitka spruce and provides a general evaluation of site hazard for any forest crop based on its location, together with estimates of the disease risks associated with stumps and standing trees of different species.
Abstract: Summary Heterobasidion annosum causes serious root disease in conifers: pines are generally killed but other species, such as Sitka spruce, are more susceptible to decay. In the mid-twentieth century, much of the expanding forest estate in Britain was disease free, but as thinning increased in plantations established over the preceding 30 years, it was expected that stump infection would increase; this in turn was expected to give rise to widespread disease. As a control, mandatory stump treatment using various chemicals, or a biological agent, was introduced throughout the Forestry Commission’s estate in 1960. Since that time inoculation experiments have shown that the risk of infection in Sitka spruce varies from site-to-site and is much lower in crops growing on peaty soils than in those on mineral soils. To help predict future losses, a simulation model was devised to describe the behaviour of disease caused by H. annosum in Sitka spruce. It was used to integrate the results of work described here with those obtained from other experiments and from field observations made over many years. Losses were estimated over one or more rotations under various management regimes. Cost–benefit calculations indicated that treatment of Sitka spruce stumps was not likely to be economically justified on upland sites with peaty soils. As a result, the policy of universal stump protection was revised in 2000, so that treatment of Sitka spruce stumps was discontinued on deeper peats and became discretionary on all peaty soils in areas of high rainfall. Implementation of the policy was challenging since soil maps were not available for many forests, and in areas of high rainfall an intimate mosaic of peat and mineral soils often forms in response to local variations in topography. A stump treatment decision support system was developed based on a comprehensive geographic information system map of mainland Britain. This provides a general evaluation of site hazard for any forest crop based on its location, together with estimates of the disease risks associated with stumps and standing trees of different species. Use of this system was adopted as Forestry Commission policy in England and Scotland in 2007.
TL;DR: In this article, the authors present and synthesize several concepts and suggestions that have applicability for ameliorating these conflicts and integrate their use and requirements into a silvicultural system that is planned, executed and evaluated within and among landscapes.
Abstract: Summary In many boreal and temperate forests, ungulates are an important feature valued by many stakeholders. However, conflicts often arise due to the use of a forest by both domestic and wild ungulates and other uses such as timber production, recreation and conservation. In this paper, we present and synthesize several concepts and suggestions that have applicability for ameliorating these conflicts. The amount, location and juxtaposition of forage, water, minerals (e.g. salt, molasses blocks) and cover are major determinants of range quality and, in turn, influence how ungulates use forests. Moreover, by strategically dispersing these key elements throughout a landscape will also disperse animal use by decreasing ungulate numbers in a given area thus reducing potential conflicts with other forest uses. Other approaches such as fences, herding, coarse woody debris dispersion, stand regeneration methods and site preparation methods can also be used to influence animal movement and use. By far, the most important aspect of minimizing ungulate conflicts is to integrate their use and requirements into a silvicultural system that is planned, executed and evaluated within and among landscapes and is developed to meet non-conflicting forest management objectives.
TL;DR: In this article, two different nearest neighbor methods and generalized additive models were applied to impute individual tree 5-year diameter increment for Scots pine ( Pinus sylvestris L.) and Norway spruce ( Picea abies (L.) H. Karst.).
Abstract: Summary Two different nearest neighbour methods and generalized additive models were applied to impute individual tree 5-year diameter increment for Scots pine ( Pinus sylvestris L.) and Norway spruce ( Picea abies (L.) H. Karst.). The aim was to compare the performance of different types of non-parametric methods when observations in the data are correlated. The study was implemented by defi ning different restrictions to the pool of possible reference trees. Observations from the same stand as the target tree are usually excluded while applying non-parametric imputation and cross-validation methods for evaluation. However, the nearest neighbours may all be selected from one particular stand, if the stand-level variables contain much weight in the distance function, and the neighbours are selected based on these stand-level variables. This may affect the stand-level results – for example, if the neighbours of a tree growing in a damp site are all selected from a dry site. The results showed that in general the differences in accuracy among the different methods and restriction alternatives were not remarkable under the assumption that the trees from the same stand as the target tree were excluded. However, the stand-level and regional results were slightly improved by not including many neighbours from one stand, implying that using many similar neighbours is an ineffi cient procedure. Hence, restricting the number of mutually correlated neighbours would be appropriate when considering the accuracy of stand-level or regional growth estimates.
TL;DR: This study, which provides the first detailed species level identification of plantation tree pathogens in Zambia, provides a foundation for future work to develop management strategies aimed at reducing the impact of plantation diseases in the country.
Abstract: Summary Commercial forestry plantations in Zambia were initiated during the 1960s. Since then, very little attention has been given to diseases that impact negatively on the production of these plantations. Recent field surveys have highlighted the occurrence and impact of several diseases. This study was undertaken to determine, to species level, the identity of fungal pathogens associated with diseases of eucalypt and pine plantations in the country. Fungal morphology and DNA sequence data of the internal transcribed spacer (ITS) and β-tubulin gene regions were used to characterize isolates. Eleven fungal species were identified of which Teratospheria zuluensis, causing Coniothyrium canker, and Lasiodiplodia theobromae, causing stem canker and die-back on Eucalyptus spp., were the most serious and prevalent. A serious post-emergence damping-off disease of Pinus oocarpa and Pinus kesiya seedlings in nurseries yielded Calonectria pauciramosum. This study, which provides the first detailed species level identification of plantation tree pathogens in Zambia, provides a foundation for future work to develop management strategies aimed at reducing the impact of plantation diseases in the country.
TL;DR: In this paper, the authors studied the deadwood dynamics in hardwood forests in the Acadian Forest Region and found that sugar maple, yellow birch, American beech, white birch and red maple are the most common hardwood species in this region.
Abstract: Deadwood – consisting of dead standing trees (snags), woody debris (WD; downed deadwood), buried wood and stumps – is an important yet poorly documented component of forest structure. Deadwood is important to carbon cycles (e.g. Kurz and Apps, 1993), provides growing and breeding habitat for a range of species, including saproxylic plants, fungi and animals (Kruys and Jonsson, 1999; Harmon et al., 2004; Norden et al., 2004). Deadwood is also an important habitat for southern flying squirrels (Glaucomys volans Linnaeus), which are endangered in Nova Scotia (Stabb, 1987). However, deadwood dynamics in northeastern North American hardwood forests have not received the same attention as other forest ecosystems and there is a dearth of information for Nova Scotia hardwood forests. Hence, forest dynamics of the northeastern USA and inland Canada are implied to apply to the whole of the Acadian Forest Region (Rowe, 1972), which includes Nova Scotia (e.g. Mosseler et al., 2003). Forests dominated by sugar maple (Acer saccharum L.), yellow birch (Betula alleghaniensis Britton), American beech (Fagus grandifolia Ehrh), white birch (Betula papyrifera Marsh) and red maple (Acer rubum L.) are common from the coast of New England, USA and Maritime Canada inland to southern Ontario and Quebec, Canada, Minnesota and Wisconsin, USA. Forests dominated by these species grow at their northeastern limit in Nova Scotia, which is more influenced by a maritime climate resulting in high winds, more frequent ice storms and cooler summers than most of their range. Thus, yields and tree dimensions of Nova Scotia’s hardwood forests are potentially lower than southern and inland hardwood forests, likely producing less deadwood consisting of smaller pieces that are less persistent on the landscape. Hardwood forests dominated by sugar maple, yellow birch and beech constitute 23 per cent of the potential late successional forests of Nova Scotia. Mixed woods composed of softwood, maple, birch and beech represent a further 11 per cent of the potential climax forests of Nova Scotia (Stewart et al., 2003). While the area of Nova Scotia dominated by the above species is unknown, Nova Scotia is estimated to contain a total merchantable volume of 132.1 million m3 of hardwood, consisting of 57.6, 19.4, Deadwood abundance in recently harvested and old Nova Scotia hardwood forests
TL;DR: In this paper, a simple urn model for species richness estimator applicable to quadrat sampling from a fixed-area sessile population composed of N quadrats is proposed.
Abstract: Summary A simple urn model species richness estimator applicable to quadrat sampling from a fixed-area sessile population composed of N quadrats is proposed. The urn model rests on the assumption that the proportion of quadrats with species that occurred in just one of the n sampled quadrats is proportional to the probability of discovering a new species if one quadrat is added to the sample. The urn model works by making one-step-ahead sequential predictions of new species discoveries for all N − n quadrats not in the original sample. The probability of a new discovery changes dynamically as predictions are made. The urn scheme is repeated a large number of times to yield a resampling distribution of richness from which the mean is obtained as the estimate of richness. The variance of the resampling distribution quantifies the prediction variance. Quantiles (0.025 and 0.975) of the resampling distribution were taken as the upper and lower limit of a 95 per cent confidence interval for the true richness. In simulated low-intensity quadrat sampling from 10 fixed-area populations of forest trees, the urn estimator had the lowest bias and root meansquared errors and the best coverage of 95 per cent confidence intervals. Attractive ‘asymptotic’ properties of the urn model were demonstrated with three artificial benchmark populations.