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Forests, Volume 4, Issue 3 (September 2013), Pages 518-729

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Editorial

Jump to: Research, Review

Open AccessEditorial Narrative History of the Resistance Screening Center: It’s Origins, Leadership and Partial List of Public Benefits and Scientific Contributions
Forests 2013, 4(3), 666-692; doi:10.3390/f4030666
Received: 13 June 2013 / Revised: 24 June 2013 / Accepted: 2 August 2013 / Published: 22 August 2013
Cited by 3 | PDF Full-text (1267 KB) | HTML Full-text | XML Full-text
Abstract
Forty years ago, the US Department of Agriculture (USDA) Forest Service developed and currently operates the Resistance Screening Center near Asheville, North Carolina, as a service to both industry and university-based tree improvement programs and tree-seed exporting companies in the southern US, [...] Read more.
Forty years ago, the US Department of Agriculture (USDA) Forest Service developed and currently operates the Resistance Screening Center near Asheville, North Carolina, as a service to both industry and university-based tree improvement programs and tree-seed exporting companies in the southern US, Mexico, and Central America. Seed lots from more than 15,000 selections of slash and loblolly pines have been evaluated for genetically-controlled resistance to fusiform rust and other diseases including pitch canker, dogwood anthracnose, and brown spot needle blight. The screening system uses a greenhouse-based artificial inoculation system with controlled density of inoculum from geographically diverse sources of the rust pathogen. Results are completed in 6–9 months and are reasonably well-correlated with field-based progeny tests. Operating costs of the Center are shared by both the USDA Forest Service and its clients. The technologically sophisticated methods and professional skills of the Center staff have been applied to facilitate and accelerate progress in region-wide timber production, scientific understanding of the fusiform rust pathosystem, and graduate education of forest geneticists and pathologists in universities. Full article
(This article belongs to the Special Issue Fusiform Rust Disease—Biology and Management of Resistance)
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Research

Jump to: Editorial, Review

Open AccessArticle Canopy Structural Changes Following Widespread Mortality of Canopy Dominant Trees
Forests 2013, 4(3), 537-552; doi:10.3390/f4030537
Received: 24 May 2013 / Revised: 28 June 2013 / Accepted: 2 July 2013 / Published: 8 July 2013
Cited by 4 | PDF Full-text (571 KB) | HTML Full-text | XML Full-text
Abstract
Canopy structure affects forest function by determining light availability and distribution. Many forests throughout the upper Great Lakes region are dominated by mature, even-aged, early successional aspen and birch, which comprise 35%–40% of canopy leaf area, and which are senescing at accelerating [...] Read more.
Canopy structure affects forest function by determining light availability and distribution. Many forests throughout the upper Great Lakes region are dominated by mature, even-aged, early successional aspen and birch, which comprise 35%–40% of canopy leaf area, and which are senescing at accelerating rates. In 2008 at the University of Michigan Biological Station, we initiated the Forest Accelerated Succession ExperimenT (FASET) by stem girdling all aspen and birch in replicated stands to induce mortality. Our objective was to understand type and rate of canopy structural changes imposed by rapid but diffuse disturbance consisting of mortality of a single age-species cohort. We characterized changes in canopy structural features in 2008–2011 using ground-based Portable Canopy Lidar (PCL) in paired treated and control stands. As aspen and birch in treated plots died, gap fraction of the upper canopy increased, average leaf height decreased, total canopy height declined, and openness of the whole-canopy increased. All of these trends became more pronounced with time. Our findings suggest that as forests throughout the region pass through the impending successional transition prompted by widespread mortality of canopy-dominant early successional aspen and birch species, the canopy will undergo significant structural reorganization with consequences for forest carbon assimilation. Full article
Open AccessArticle Strategy Pattern Creation in Forest Planning in Swedish Forest-Owning Companies
Forests 2013, 4(3), 553-574; doi:10.3390/f4030553
Received: 14 June 2013 / Revised: 2 July 2013 / Accepted: 4 July 2013 / Published: 10 July 2013
Cited by 1 | PDF Full-text (609 KB) | HTML Full-text | XML Full-text
Abstract
Forest-owning companies in Sweden have both a goal to yield a good short-term rate of return on their forest and a goal to maintain a high long-term rate of return by maintaining the production of wood-based products. Both these objectives are taken [...] Read more.
Forest-owning companies in Sweden have both a goal to yield a good short-term rate of return on their forest and a goal to maintain a high long-term rate of return by maintaining the production of wood-based products. Both these objectives are taken into account in the forest planning process. For the long-term goal, the companies develop strategies formulated in the forest planning system and for the short-term goal, sale strategies are formulated in the sale plans. These strategies may raise conflicts on how to use the forest resources. These conflicts would occur in the work with the tract bank (TB), the register of stands ready for harvesting. The objective of this study was to analyze how Swedish forest owning companies form their strategy patterns around the work with the TB and to discuss the implications of the pattern formation for forest planning in the companies. Planners and harvest managers at three large forest-owning companies responded to a questionnaire. The results show that the delivery plan based on the sale strategy is often a main factor in determining the content of the TB. Full article
Open AccessArticle Genetic Improvement of White Spruce Mechanical Wood Traits—Early Screening by Means of Acoustic Velocity
Forests 2013, 4(3), 575-594; doi:10.3390/f4030575
Received: 7 May 2013 / Revised: 25 June 2013 / Accepted: 27 June 2013 / Published: 10 July 2013
Cited by 10 | PDF Full-text (628 KB) | HTML Full-text | XML Full-text
Abstract
There is a growing interest to use acoustic sensors for selection in tree breeding to ensure high wood quality of future plantations. In this study, we assessed acoustic velocity as a selection trait for the improvement of mechanical wood properties in two [...] Read more.
There is a growing interest to use acoustic sensors for selection in tree breeding to ensure high wood quality of future plantations. In this study, we assessed acoustic velocity as a selection trait for the improvement of mechanical wood properties in two 15- and 32-year-old white spruce (Picea glauca [Moench.] Voss) genetic tests. Individual heritability of acoustic velocity was moderate and of the same magnitude as heritability of wood density. Considerable genetic gain could be expected for acoustic velocity and a measure combining velocity and wood density. The relationship between acoustic velocity and cellulose microfibril angle (MFA) was strong on the genetic level and selection based on velocity could effectively improve MFA, which is one of the most important determinants of wood mechanical properties. Although low, the positive relationship between acoustic velocity and tree height presents an interesting opportunity for the improvement of both tree growth and wood quality. On the phenotypic level, MFA was more strongly correlated to acoustic velocity in mature trees than in young trees. The addition of easily obtainable traits such as diameter at breast height (DBH), height-to-diameter ratio as well as wood density to velocity determinations could improve models of MFA at the young and the mature age. We conclude that juvenile acoustic velocity is an appropriate trait to select for wood quality in a tree breeding context. Full article
(This article belongs to the Special Issue Improving Wood Quality from Planted Forests)
Open AccessArticle Foliage and Litter Chemistry, Decomposition, and Nutrient Release in Pinus taeda
Forests 2013, 4(3), 595-612; doi:10.3390/f4030595
Received: 3 May 2013 / Revised: 9 June 2013 / Accepted: 1 July 2013 / Published: 17 July 2013
Cited by 3 | PDF Full-text (912 KB) | HTML Full-text | XML Full-text
Abstract
Following fertilization of forest plantations, high accumulations of nutrients in the forest floor creates the need to assess rates of forest floor decomposition and nutrient release. The study site was a 25-year old experimental loblolly pine plantation in the North Carolina Sandhills [...] Read more.
Following fertilization of forest plantations, high accumulations of nutrients in the forest floor creates the need to assess rates of forest floor decomposition and nutrient release. The study site was a 25-year old experimental loblolly pine plantation in the North Carolina Sandhills Region. Soluble and insoluble N, P, carbohydrate and phenol-tannin fractions were determined in foliage and litter by extraction with trichloroacetic acid. The long-term forest floor decomposition rate and decomposition and nutrient release in an experiment simulating removal of the overstory canopy were also determined. In litter, insoluble protein-N comprised 80%–90% of total-N concentration while soluble inorganic- and organic-P comprised 50%–75% of total-P concentration explaining forest floor N accumulations. Fertilization did not increase soluble carbohydrates in litter and forest floor decomposition rates. Loblolly pine forest floor decomposing in environmental conditions simulating removal of the overstory canopy was greatly accelerated and indicated 75% mass loss and release of 80% of the N pool within one year. This could result in a loss of substantial quantities of N at harvest due to low N uptake by seedlings in the newly planted next rotation suggesting management of the forest floor at harvest is essential to conserve site N capital in these N limited systems. Full article
Open AccessArticle Distribution and Variation of Forests in China from 2001 to 2011: A Study Based on Remotely Sensed Data
Forests 2013, 4(3), 632-649; doi:10.3390/f4030632
Received: 7 June 2013 / Revised: 7 July 2013 / Accepted: 15 July 2013 / Published: 2 August 2013
Cited by 5 | PDF Full-text (848 KB) | HTML Full-text | XML Full-text
Abstract
Forests are one of the most important components of the global biosphere and have critical influences on the Earth’s ecological balance. Regularly updated forest cover information is necessary for various forest management applications as well as climate modeling studies. However, map products [...] Read more.
Forests are one of the most important components of the global biosphere and have critical influences on the Earth’s ecological balance. Regularly updated forest cover information is necessary for various forest management applications as well as climate modeling studies. However, map products are not widely updated at continental or national scales because the current land cover products have overly coarse spatial resolution or insufficiently large training data sets. This study presents the results of forests distribution and variation information over China using Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) time series data with the first layer of MODIS Land Cover Type product (MODIS LC-1). The NDVI time series histogram characteristic curves for forestland were estimated from MODIS LC-1 and MODIS NDVI time series data. Based on the differences of histograms among different forests, we obtained the 2001–2011 forests distribution for China at a spatial resolution of 500-m × 500-m. The overall accuracy of validation was 80.4%, an increase of 12.8% relative to that obtained using MODIS LC-1 data. The 2001–2011 forestland pure and mixed pixels of China accounted for an average of 33.72% of all pixels. There is a gradual increase in China’s forestland coverage during 2001–2011; however, the relationship is not statistically significant. Full article
(This article belongs to the Special Issue Forest Restoration and Regeneration)
Open AccessArticle Tree Species Richness and Stand Productivity in Low-Density Cluster Plantings with Oaks (Quercus robur L. and Q. petraea (Mattuschka) Liebl.)
Forests 2013, 4(3), 650-665; doi:10.3390/f4030650
Received: 1 July 2013 / Revised: 8 August 2013 / Accepted: 9 August 2013 / Published: 16 August 2013
Cited by 4 | PDF Full-text (1348 KB) | HTML Full-text | XML Full-text
Abstract
Low density plantings complemented by natural regeneration is an increasingly common reforestation technique to ensure growth of a sufficient number of trees from desired species while maintaining natural processes such as succession. One such form of low density planting that aims at [...] Read more.
Low density plantings complemented by natural regeneration is an increasingly common reforestation technique to ensure growth of a sufficient number of trees from desired species while maintaining natural processes such as succession. One such form of low density planting that aims at lowering establishment costs—oak clusters—has been developed as an alternative to row planting since the 1980s in central Europe. However, whether cluster planting provides higher species richness and productivity than high density row planting has not previously been analyzed. Here, we compare tree species richness and productivity (measured as stand basal area) between oak cluster plantings and conventional row planting in young (10–26 years old) forest stands at seven study sites in Germany. Tree species richness was significantly higher in cluster plantings than in row plantings, whereas total basal areas were comparable. Naturally regenerated trees contributed on average to 43% of total stand basal area in cluster plantings, which was significantly higher than in row plantings. Total stand basal area in cluster planting was significantly related to the density of naturally regenerated trees. In turn, tree species diversity, density and basal area of naturally regenerated trees were increased with the size of unplanted area between clusters. Our results demonstrate that the admixture of naturally regenerated, early and mid-successional tree species compensates for a possible loss in productivity from planting fewer oaks. Low density cluster plantings can offer significant environmental benefits, at least for the first few decades of stand development, without compromising productivity. Full article
(This article belongs to the Special Issue Feature papers (2013))
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Open AccessArticle How to Influence Forest-Related Issues in the European Union? Preferred Strategies among Swedish Forest Industry
Forests 2013, 4(3), 693-709; doi:10.3390/f4030693
Received: 14 May 2013 / Revised: 21 June 2013 / Accepted: 8 August 2013 / Published: 28 August 2013
Cited by 2 | PDF Full-text (513 KB) | HTML Full-text | XML Full-text
Abstract
Although forestry is not a regulated area in the European Union (EU), numerous decisions in other policy areas are related to forestry. However, its position outside of formal policy-making can result in the fact that actors, such as those within the forest [...] Read more.
Although forestry is not a regulated area in the European Union (EU), numerous decisions in other policy areas are related to forestry. However, its position outside of formal policy-making can result in the fact that actors, such as those within the forest industry, may have a larger role when compared to other policy sectors where the state system has an integrated role. This explorative study reviews the ways in which the forest industry in Sweden, one of the EU states with the most forest land, tries to protect and promote its interests on an EU-level. It concludes that a main way to influence decision-making in the EU is through lobbying, through its own organisations and through the transnational trade association, The Confederation of European Paper Industries (CEPI). The study shows that collectively conducted lobbying is largely preferred which means that internal communication is important since lobbying at the EU-level is potentially limited by the diverging positions of trade association members as well as among the different trade associations themselves. Full article
Open AccessArticle Indicators and Determinants of Small-Scale Bamboo Commercialization in Ethiopia
Forests 2013, 4(3), 710-729; doi:10.3390/f4030710
Received: 21 June 2013 / Revised: 4 September 2013 / Accepted: 9 September 2013 / Published: 18 September 2013
PDF Full-text (586 KB) | HTML Full-text | XML Full-text
Abstract
Bamboo is an abundant resource in Ethiopia and has a great potential for commercialization, which can drive rural development. In view of these realities, this study analyzed the state and determinants of small-scale bamboo commercialization in Ethiopia. Data were collected from three [...] Read more.
Bamboo is an abundant resource in Ethiopia and has a great potential for commercialization, which can drive rural development. In view of these realities, this study analyzed the state and determinants of small-scale bamboo commercialization in Ethiopia. Data were collected from three major bamboo-growing districts (Awi, Sidama, and Sheka) and four urban centers (Masha, Hawassa, Bahir Dar, and Addis Ababa) via semi-structured interviews, group discussions, and questionnaire surveys with key actors along the value chain. Results revealed distinctive differences in proportion of cash income, value chain structure, and management engagement among the districts. Percentages of cash income were 60.15, 42.60, and 9.48 at Awi, Sidam, and Sheka, respectively. Differences were statistically significant between Sheka and both other districts (p = 0.05), but not between Awi and Sidama. The value chain structure showed that compared with Sheka, Awi and Sidama have a relatively large number of actors involved. The major factors explaining commercialization differences among regions were distance to market and presence of alternative forest products. Within Sheka, households with larger family size, higher education attainment, and access to training reportedly engaged more in commercial extraction. Therefore, we conclude that development of infrastructure for linking resource and consumer centers and expansion of extension education among producers may enhance the commercial engagement of producers and improve the accessibility of bamboo resources for commercial production. Full article

Review

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Open AccessReview The Utility of Image-Based Point Clouds for Forest Inventory: A Comparison with Airborne Laser Scanning
Forests 2013, 4(3), 518-536; doi:10.3390/f4030518
Received: 17 May 2013 / Revised: 17 June 2013 / Accepted: 19 June 2013 / Published: 26 June 2013
Cited by 49 | PDF Full-text (688 KB) | HTML Full-text | XML Full-text
Abstract
Airborne Laser Scanning (ALS), also known as Light Detection and Ranging (LiDAR) enables an accurate three-dimensional characterization of vertical forest structure. ALS has proven to be an information-rich asset for forest managers, enabling the generation of highly detailed bare earth digital elevation [...] Read more.
Airborne Laser Scanning (ALS), also known as Light Detection and Ranging (LiDAR) enables an accurate three-dimensional characterization of vertical forest structure. ALS has proven to be an information-rich asset for forest managers, enabling the generation of highly detailed bare earth digital elevation models (DEMs) as well as estimation of a range of forest inventory attributes (including height, basal area, and volume). Recently, there has been increasing interest in the advanced processing of high spatial resolution digital airborne imagery to generate image-based point clouds, from which vertical information with similarities to ALS can be produced. Digital airborne imagery is typically less costly to acquire than ALS, is well understood by inventory practitioners, and in addition to enabling the derivation of height information, allows for visual interpretation of attributes that are currently problematic to estimate from ALS (such as species, health status, and maturity). At present, there are two limiting factors associated with the use of image-based point clouds. First, a DEM is required to normalize the image-based point cloud heights to aboveground heights; however DEMs with sufficient spatial resolution and vertical accuracy, particularly in forested areas, are usually only available from ALS data. The use of image-based point clouds may therefore be limited to those forest areas that already have an ALS-derived DEM. Second, image-based point clouds primarily characterize the outer envelope of the forest canopy, whereas ALS pulses penetrate the canopy and provide information on sub-canopy forest structure. The impact of these limiting factors on the estimation of forest inventory attributes has not been extensively researched and is not yet well understood. In this paper, we review the key similarities and differences between ALS data and image-based point clouds, summarize the results of current research related to the comparative use of these data for forest inventory attribute estimation, and highlight some outstanding research questions that should be addressed before any definitive recommendation can be made regarding the use of image-based point clouds for this application. Full article
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Open AccessReview Managing Understory Vegetation for Maintaining Productivity in Black Spruce Forests: A Synthesis within a Multi-Scale Research Model
Forests 2013, 4(3), 613-631; doi:10.3390/f4030613
Received: 14 June 2013 / Revised: 11 July 2013 / Accepted: 12 July 2013 / Published: 23 July 2013
Cited by 7 | PDF Full-text (1450 KB) | HTML Full-text | XML Full-text
Abstract
Sustainable management of boreal ecosystems involves the establishment of vigorous tree regeneration after harvest. However, two groups of understory plants influence regeneration success in eastern boreal Canada. Ericaceous shrubs are recognized to rapidly dominate susceptible boreal sites after harvest. Such dominance reduces [...] Read more.
Sustainable management of boreal ecosystems involves the establishment of vigorous tree regeneration after harvest. However, two groups of understory plants influence regeneration success in eastern boreal Canada. Ericaceous shrubs are recognized to rapidly dominate susceptible boreal sites after harvest. Such dominance reduces recruitment and causes stagnant conifer growth, lasting decades on some sites. Additionally, peat accumulation due to Sphagnum growth after harvest forces the roots of regenerating conifers out of the relatively nutrient rich and warm mineral soil into the relatively nutrient poor and cool organic layer, with drastic effects on growth. Shifts from once productive black spruce forests to ericaceous heaths or paludified forests affect forest productivity and biodiversity. Under natural disturbance dynamics, fires severe enough to substantially reduce the organic layer thickness and affect ground cover species are required to establish a productive regeneration layer on such sites. We succinctly review how understory vegetation influences black spruce ecosystem dynamics in eastern boreal Canada, and present a multi-scale research model to understand, limit the loss and restore productive and diverse ecosystems in this region. Our model integrates knowledge of plant-level mechanisms in the development of silvicultural tools to sustain productivity. Fundamental knowledge is integrated at stand, landscape, regional and provincial levels to understand the distribution and dynamics of ericaceous shrubs and paludification processes and to support tactical and strategic forest management. The model can be adapted and applied to other natural resource management problems, in other biomes. Full article
(This article belongs to the Special Issue Forest Restoration and Regeneration)

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