Gustaf Egnell

Survival and Growth of Planted Seedlings of Pinus sylvestris and Picea abies After Different Levels of Biomass Removal in Clear-felling

To determine the effect of different harvest intensities on seedling survival and growth, two stands of Scots pine (Pinus sylvestris L.) and two of Norway spruce (Picea abies (L.) Karst) were harvested at three intensities; conventional stem - only harvest (CH); whole - tree harvest (WTH); and branch and stem harvest with needles left on site (BSH). The stands were then planted with Scots pine and Norway spruce seedlings in a randomized block design. Survival rates were lower in Scots pine following CH compared with WTH and BSH, but Norway spruce was unaffected by the harvest method. In Norway spruce, the mean height and basal area after 15 yrs were lower following WTH compared with CH and BSH. In Scots pine WFH resulted in greater mean height after five yrs at one site. No treatment effects on height were found after 7, 10, and 15 yrs. In contrast, basal area was reduced following WTH compared with CH and BSH after 15 yrs at one site, indicating a treatment effect on stem taper. Species differences in th...

Long-term effects of site preparation on growth in Scots pine.

Abstract Effects of soil scarification on long-term site productivity up to 70 years, and soil content of carbon (C), nitrogen (N), and macro nutrients, were studied in five site preparation experiments, established between 1922 and 1965 on Scots pine ( Pinus sylvestris L.) heathland, on poor sandy sediments. The soil was inverted by spade, hoed, harrowed or ploughed. All scarification methods disturbed close to 100% of the soil surface, the most radical treatments to a depth of approximately 20 cm. Some of the experiments had an inadequate original design. However, by comparing the experiments some general characteristics were found. Site productivity measured as top height was higher on scarified plots than on control plots ( P

Effects of different levels of biomass removal in thinning on short‐term production of pinus sylvestris and picea abies stands

Effects of harvest intensity in thinnings on the productivity of the remaining stands were studied in two Scots pine (Pinus sylvestris L.) and two Norway spruce (Picea abies (L.) Karst.) stands in Sweden. Treatments were: conventional stem wood harvest with short‐wood system (CH); whole‐tree harvest (WTH); whole‐tree harvest + compensation fertilization with NPK (WTH + F). No significant treatment differences in basal area increment could be detected during the first 10 yrs after harvest. However, in all four stands mean basal area increment was lower on WTH plots than on CH plots. The effects of WTH + F were inconsistent. The results indicate that WTH could be practiced in thinnings without significant short‐term production losses in Scots pine and Norway spruce stands in Sweden. However, it is to early to draw any definite conclusion on long‐term effects of WTH on site productivity.

The role of biogeochemical hotspots, landscape heterogeneity, and hydrological connectivity for minimizing forestry effects on water quality

Protecting water quality in forested regions is increasingly important as pressures from land-use, long-range transport of air pollutants, and climate change intensify. Maintaining forest industry without jeopardizing sustainability of surface water quality therefore requires new tools and approaches. Here, we show how forest management can be optimized by incorporating landscape sensitivity and hydrological connectivity into a framework that promotes the protection of water quality. We discuss how this approach can be operationalized into a hydromapping tool to support forestry operations that minimize water quality impacts. We specifically focus on how hydromapping can be used to support three fundamental aspects of land management planning including how to (i) locate areas where different forestry practices can be conducted with minimal water quality impact; (ii) guide the off-road driving of forestry machines to minimize soil damage; and (iii) optimize the design of riparian buffer zones. While this work has a boreal perspective, these concepts and approaches have broad-scale applicability.

Woodfuel Harvesting: A Review of Environmental Risks, Criteria and Indicators, and Certification Standards for Environmental Sustainability

Forest bioenergy feedstock production and harvesting systems range from small-scale fuelwood gathering to large-scale industrial plantations and the potential removal of all available aboveground and belowground biomass from intensively managed forests. Across this wide range of options for production and extraction, there is an equally wide range of potential impacts. It is critical that forest biomass procurement systems do not adversely impact forests or the environment; therefore, effective standards and planning tools, based on the best available scientific knowledge, must be in place to prevent these impacts from being realized, and hence ensure a sustainable industry. Sustainable forest management (SFM) certification schemes are one mechanism for applying measurable environmental standards (in the form of criteria and indicators, or C&I) to forest management systems. How existing SFM certification schemes and frameworks, such as C&I and Adaptive Forest Management, can be used to help guide sustainable biomass operations is discussed. The potential impacts of biomass production and harvesting on soil and water resources, site productivity and biodiversity in the forest, as well as issues related to greenhouse gas balances and global and supply-chain impacts, are evaluated. An example is then given of how principles and criteria for sustainable biomass production can be used to address these potential impacts.

Status and prospects for renewable energy using wood pellets from the southeastern United States

The ongoing debate about costs and benefits of wood‐pellet based bioenergy production in the southeastern United States (SE USA) requires an understanding of the science and context influencing market decisions associated with its sustainability. Production of pellets has garnered much attention as US exports have grown from negligible amounts in the early 2000s to 4.6 million metric tonnes in 2015. Currently, 98% of these pellet exports are shipped to Europe to displace coal in power plants. We ask, ‘How is the production of wood pellets in the SE USA affecting forest systems and the ecosystem services they provide?’ To address this question, we review current forest conditions and the status of the wood products industry, how pellet production affects ecosystem services and biodiversity, and what methods are in place to monitor changes and protect vulnerable systems. Scientific studies provide evidence that wood pellets in the SE USA are a fraction of total forestry operations and can be produced while maintaining or improving forest ecosystem services. Ecosystem services are protected by the requirement to utilize loggers trained to apply scientifically based best management practices in planning and implementing harvest for the export market. Bioenergy markets supplement incomes to private rural landholders and provide an incentive for forest management practices that simultaneously benefit water quality and wildlife and reduce risk of fire and insect outbreaks. Bioenergy also increases the value of forest land to landowners, thereby decreasing likelihood of conversion to nonforest uses. Monitoring and evaluation are essential to verify that regulations and good practices are achieving goals and to enable timely responses if problems arise. Conducting rigorous research to understand how conditions change in response to management choices requires baseline data, monitoring, and appropriate reference scenarios. Long‐term monitoring data on forest conditions should be publicly accessible and utilized to inform adaptive management.

Infrared thermography as a means of assessing seedling quality

The possibility of using infrared thermography as seedling vitality test before planting was investigated. The temperature of seedlings of Scots pine and Norway spruce was determined in the laboratory before planting using the AGA Thermovision System. It was found that the field performance conformed to the IR measurements of the seedlings. The “cold”; (high‐transpiring) seedlings performed better than the “warm”; (low‐transpiring) ones. Some of the measurement problems discussed concern illumination and the interpretation of the thermo‐grams because of the small size of conifer needles. The IR measurements might be a tool in a future system for grading seedlings.

Carbon balances of bioenergy systems using biomass from forests managed with long rotations: bridging the gap between stand and landscape assessments

Studies report different findings concerning the climate benefits of bioenergy, in part due to varying scope and use of different approaches to define spatial and temporal system boundaries. We quantify carbon balances for bioenergy systems that use biomass from forests managed with long rotations, employing different approaches and boundary conditions. Two approaches to represent landscapes and quantify their carbon balances – expanding vs. constant spatial boundaries – are compared. We show that for a conceptual forest landscape, constructed by combining a series of time‐shifted forest stands, the two approaches sometimes yield different results. We argue that the approach that uses constant spatial boundaries is preferable because it captures all carbon flows in the landscape throughout the accounting period. The approach that uses expanding system boundaries fails to accurately describe the carbon fluxes in the landscape due to incomplete coverage of carbon flows and influence of the stand‐level dynamics, which in turn arise from the way temporal system boundaries are defined on the stand level. Modelling of profit‐driven forest management using location‐specific forest data shows that the implications for carbon balance of management changes across the landscape (which are partly neglected when expanding system boundaries are used) depend on many factors such as forest structure and forest owners’ expectations of market development for bioenergy and other wood products. Assessments should not consider forest‐based bioenergy in isolation but should ideally consider all forest products and how forest management planning as a whole is affected by bioenergy incentives – and how this in turn affects carbon balances in forest landscapes and forest product pools. Due to uncertainties, we modelled several alternative scenarios for forest products markets. We recommend that future work consider alternative scenarios for other critical factors, such as policy options and energy technology pathways.

The effects of logging residue extraction for energy on ecosystem services and biodiversity : a synthesis

We review the consequences for biodiversity and ecosystem services from the industrial-scale extraction of logging residues (tops, branches and stumps from harvested trees and small-diameter trees from thinnings) in managed forests. Logging residue extraction can replace fossil fuels, and thus contribute to climate change mitigation. The additional biomass and nutrients removed, and soils and other structures disturbed, have several potential environmental impacts. To evaluate potential impacts on ecosystem services and biodiversity we reviewed 279 scientific papers that compared logging residue extraction with non-extraction, the majority of which were conducted in Northern Europe and North America. The weight of available evidence indicates that logging residue extraction can have significant negative effects on biodiversity, especially for species naturally adapted to sun-exposed conditions and the large amounts of dead wood that are created by large-scaled forest disturbances. Slash extraction may also pose risks for future biomass production itself, due to the associated loss of nutrients. For water quality, reindeer herding, mammalian game species, berries, and natural heritage the results were complicated by primarily negative but some positive effects, while for recreation and pest control positive effects were more consistent. Further, there are initial negative effects on carbon storage, but these effects are transient and carbon stocks are mostly restored over decadal time perspectives. We summarize ways of decreasing some of the negative effects of logging residue extraction on specific ecosystem services, by changing the categories of residue extracted, and site or forest type targeted for extraction. However, we found that suggested pathways for minimizing adverse outcomes were often in conflict among the ecosystem services assessed. Compensatory measures for logging residue extraction may also be used (e.g. ash recycling, liming, fertilization), though these may also be associated with adverse environmental impacts.

Chapter 4 – Environmental Sustainability Aspects of Forest Biomass Mobilisation

The environmental sustainability of forest biomass procurement needs to be well understood, as the capacity of ecosystems to provide biomass, without negative impacts on ecological functioning, limits the biomass potential. Emerging bioenergy markets typically first take advantage of secondary residue streams of various wood processing industries and tertiary end-of-life residues. The use of these secondary and tertiary wood resources is not likely to compromise the environmental sustainability of forests. When these resources, in any region, become scarce or fully utilised, primary residues (ie by-products of forestry harvesting operations and silvicultural practices) such as branches, tops and non-merchantable trees become increasingly targeted as feedstock sources. Forest biomass procurement in the boreal and temperate biomes should therefore not be analysed as a stand-alone activity, but rather as an intensification of land use and of forest management, in which tree parts and trees are harvested, in addition to conventional forest product fractions. Thus, principles of protection and sustainability should remain the same, whether forests are managed for conventional forest products only or also for biomass for energy. Some modifications may be needed to properly identify and find mitigation strategies for sensitive conditions where field evidence suggests that the incremental removal of biomass, or other forms of intensive management, may not be sustainable. Silvicultural practices, such as fertilisation, competition control and soil preparation are options to manage the microenvironment and tree growing conditions, as well to prevent or mitigate negative impacts. Moreover, landscape management regulations should be put in place to ensure that sufficient biodiversity-important features, such as dead wood, aging stands, corridors, etc., are preserved. Special attention should then be directed to trees and stands with high biodiversity values, or those important for maintaining ecosystem services. Applying the concept of adaptive forest management, ecological monitoring following harvesting operations, scientific field testing and modelling should be combined to produce better knowledge that could help improve practices. The forestry sector needs to start adapting to a future situation where it is expected to provide conventional forest products, biomaterials and bioenergy. To achieve this, good governance mechanisms, such as landscape-level land-use planning and science-based improvements of practices, will become increasingly important to ensure sustainable forest product supply chains.