Trends in global wildfire potential in a changing climate

The trend in global wildfire potential under the climate change due to the greenhouse effect is investigated. Fire potential is measured by the Keetch-Byram Drought Index (KBDI), which is calculated using the observed maximum temperature and precipitation and projected changes at the end of this century (2070–2100) by general circulation models (GCMs) for present and future climate conditions, respectively. It is shown that future wildfire potential increases significantly in the United States, South America, central Asia, southern Europe, southern Africa, and Australia. Fire potential moves up by one level in these regions, from currently low to future moderate potential or from moderate to high potential. Relative changes are the largest and smallest in southern Europe and Australia, respectively. The period with the KBDI greater than 400 (a simple definition for fire season in this study) becomes a few months longer. The increased fire potential is mainly caused by warming in the U.S., South America, and Australia and by the combination of warming and drying in the other regions. Sensitivity analysis shows that future fire potential depends on many factors such as climate model and emission scenario used for climate change projection. The results suggest dramatic increases in wildfire potential that will require increased future resources and management efforts for disaster prevention and recovery.     

Carbon sequestration in the growing stock of trees in Finland under different cutting and climate scenarios

In this work the aim was to determine how carbon sequestration in the growing stock of trees in Finland is dependent on the forest management and increased production potential due to climate change. This was analysed for the period 2003–2053 using forest inventory data and the forestry model MELA. Four combinations of two climate change and two management scenarios were studied: current (CU) and gradually warming (CC) climate and forest management strategies corresponding to different rates of utilisation of the cutting potential, namely maximum sustainable removal (Sust) or maximum net present value (NPV) of wood production (Max). In this analysis of Finland, the initial amount of carbon in the growing stock was 765 Mt (2,802 Tg CO₂). At the end of the simulation, the carbon in the growing stock of trees in Finland had increased to 894 Mt (3,275 Tg CO₂) under CUSust, 906 Mt (3,321 Tg CO₂) under CUMax, 1,060 Mt (3,885 Tg CO₂) under CCSust and 1,026 Mt (3,758 Tg CO₂) under CCMax. The results show that future development of carbon in the growing stock is not only dependent on climate change scenarios but also on forest management. For example, maximising the NPV of wood production without sustainability constraints results, over the short term, in a large amount of wood obtained in regeneration cuttings and a consequent decrease in the amount of carbon in growing stock. Over the longer term, this decrease in the carbon of growing stock in regenerated forests is compensated by the subsequent increase in fast-growing young forests. By comparison, no drastic short-term decrease in carbon stock was found in the Sust scenarios; only minor decreases were observed.     

不同处理方法对杨树木材压缩变形恢复率的研究

采用加热和水蒸气处理方法对人工林杨树木材进行压缩变形恢复率的研究,目的是为了改善人工林软质木材的材性,提高其尺寸稳定性。结果表明:加热和水蒸气处理都是固定人工林木材压缩变形的有效方法;在处理温度相同时,水蒸气处理方法只需要4 min或8 min,而高温加热处理需要10 h或20 h。水蒸气处理方法更加经济。     

High-severity wildfire effects on carbon stocks and emissions in fuels treated and untreated forest

Forests contain the world's largest terrestrial carbon stocks, but in seasonally dry environments stock stability can be compromised if burned by wildfire, emitting carbon back to the atmosphere. Treatments to reduce wildfire severity can reduce emissions, but with an immediate cost of reducing carbon stocks. In this study we examine the tradeoffs in carbon stock reduction and wildfire emissions in 19 fuels-treated and -untreated forests burned in twelve wildfires. The fuels treatment, a commonly used thinning ‘from below’ and removal of activity fuels, removed an average of 50.3 Mg C ha⁻¹ or 34% of live tree carbon stocks. Wildfire emissions averaged 29.7 and 67.8 Mg C ha⁻¹ in fuels treated and untreated forests, respectively. The total carbon (fuels treatment plus wildfire emission) removed from treated sites was 119% of the carbon emitted from the untreated/burned sites. However, with only 3% tree survival following wildfire, untreated forests averaged only 7.8 Mg C ha⁻¹ in live trees with an average quadratic mean tree diameter of 21 cm. In contrast, treated forest averaged 100.5 Mg C ha⁻¹ with a live tree quadratic mean diameter of 44 cm. In untreated forests 70% of the remaining total ecosystem carbon shifted to decomposing stocks after the wildfire, compared to 19% in the fuels-treated forest. In wildfire burned forest, fuels treatments have a higher immediate carbon ‘cost’, but in the long-term may benefit from lower decomposition emissions and higher carbon storage.     

Carbon inventory methods and carbon mitigation potentials of forests in Europe: a short review of recent progress

The role of European forests and forest management in the carbon balance has received much attention in research recently. This was particularly motivated by the recognition of forest management as one possible measure countries may adopt in the framework of the Kyoto Protocol to reduce the concentration of greenhouse gases in the earth’s atmosphere. The main method to assess carbon budget in forests is based on traditional forest inventories. This method requires the conversion of measured stem volume to carbon pools. This conversion has been identified as a large source of uncertainty in past assessments. Over the last 5 years, intensive research efforts have resulted in significant advances in the reliability of forest inventory based carbon budgets. In parallel, the impact of forest management on the carbon balance of forest ecosystems has been investigated and the carbon mitigation potential of these activities has been analysed. This paper reviews the progress that was made in these two fields of research with a particular focus on European forests.

Forest management for mitigation and adaptation to climate change: Insights from long-term silviculture experiments

Developing management strategies for addressing global climate change has become an increasingly important issue influencing forest management around the globe. Currently, management approaches are being proposed that intend to (1) mitigate climate change by enhancing forest carbon stores and (2) foster adaptation by maintaining compositionally and structurally complex forests. However, little is known about the compatibility of these two objectives or the long-term efficacy of a given management regime at simultaneously achieving adaptation and mitigation. To address this need, we examined stand-level carbon and complexity responses using five long-term (>50 yrs) silviculture experiments within the upper Great Lakes region, USA. In particular, live tree carbon stores and sequestration rates, and compositional and structural complexity were analyzed from three thinning experiments in Pinus resinosa and two selection method experiments in northern hardwood systems to elucidate the long-term effects of management on these ecosystem attributes and the general compatibility of mitigation and adaptation objectives.As expected, we observed a general increase in large tree densities with stand age and positive relationships between stand stocking level and live tree carbon stores. More importantly, our results clearly identify tradeoffs between the achievement of mitigation and adaptation objectives across each study. For example, maintaining higher stocking levels (i.e., enhanced mitigation by increasing carbon stores) resulted in decreases in stand-level structural and compositional complexity (i.e., reduced adaptation potential). In addition, rates of live tree carbon increment were also the lowest within the highest stocking levels; despite the benefits of these stand conditions to maximizing carbon stores. Collectively, these findings underscore the importance of avoiding rigid adherence to a single objective, such as maximum on-site carbon stores, without recognizing potential consequences to other ecosystem components crucial to ensuring long-term ecosystem functioning within the context of environmental change. One potential stand-level strategy for balancing these goals may be to employ multi-aged management systems, such as irregular shelterwood and selection systems, that maintain a large proportion of carbon stores in retained mature trees while using thinning to create spatial heterogeneity that promotes higher sequestration rates in smaller, younger trees and simultaneously enhances structural and compositional complexity.