Kristina Blennow

Climate Change: Believing and Seeing Implies Adapting

Knowledge of factors that trigger human response to climate change is crucial for effective climate change policy communication. Climate change has been claimed to have low salience as a risk issue because it cannot be directly experienced. Still, personal factors such as strength of belief in local effects of climate change have been shown to correlate strongly with responses to climate change and there is a growing literature on the hypothesis that personal experience of climate change (and/or its effects) explains responses to climate change. Here we provide, using survey data from 845 private forest owners operating in a wide range of bio-climatic as well as economic-social-political structures in a latitudinal gradient across Europe, the first evidence that the personal strength of belief and perception of local effects of climate change, highly significantly explain human responses to climate change. A logistic regression model was fitted to the two variables, estimating expected probabilities ranging from 0.07 (SD ±0.01) to 0.81 (SD ±0.03) for self-reported adaptive measures taken. Adding socio-demographic variables improved the fit, estimating expected probabilities ranging from 0.022 (SD ±0.008) to 0.91 (SD ±0.02). We conclude that to explain and predict adaptation to climate change, the combination of personal experience and belief must be considered.

Risk perception among non-industrial private forest owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondents experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.

Simulating wind disturbance impacts on forest landscapes

Wind is the most detrimental disturbance agent in Europes forest ecosystems. In recent years, disturbance frequency and severity have been increasing at continental scale, a trend that is expected to continue under future anthropogenic climate change. Disturbance management is thus increasingly important for sustainable stewardship of forests, and requires tools to evaluate the effects of management alternatives and climatic changes on disturbance risk and ecosystem services. We here present a process-based model of wind disturbance impacts on forest ecosystems, integrated into the dynamic landscape simulation model iLand. The model operates at the level of individual trees and simulates wind disturbance events iteratively, i.e., dynamically accounting for changes in forest structure and newly created edges during the course of a storm. Both upwind gap size and local shelter from neighboring trees are considered in this regard, and critical wind speeds for uprooting and stem breakage are distinguished. The simulated disturbance size, pattern, and severity are thus emergent properties of the model. We evaluated the new simulation tool against satellite-derived data on the impact of the storm Gudrun (January 2005) on a 1391?ha forest landscape in south central Sweden. Both the overall damage percentage (observation: 21.7%, simulation: 21.4%) as well as the comparison of spatial damage patterns showed good correspondence between observations and predictions (prediction accuracy: 60.4%) if the full satellite-derived structural and spatial heterogeneity of the landscape was taken into account. Neglecting within-stand heterogeneity in forest conditions, i.e., the state-of-the-art in many stand-level risk models, resulted in a considerable underestimation of simulated damage, supporting the notion that tree-level complexity matters for assessing and modeling large-scale disturbances. A sensitivity analysis further showed that changes in wind speed and soil freezing could have potentially large impacts on disturbed area and patch size. The model presented here is available as open source. It can be used to study the effects of different silvicultural systems and future climates on wind risk, as well as to quantify the impacts of wind disturbance on ecosystem services such as carbon sequestration. It thus contributes to improving our capacity to address changing disturbance regimes in ecosystem management. We present a process-based model of wind disturbance impacts on forest landscapes.Stand structure is iteratively updated during a wind event.Disturbance size, pattern, and severity emerge dynamically from tree-level processes.We successfully evaluated the model against observations from the storm Gudrun.Neglecting structural and spatial heterogeneity resulted in underestimated damage.

Risk management in Swedish forestry – Policy formation and fulfilment of goals

The formation of a risk management policy in Swedish forestry and its consequences for fulfilment of goals was analysed. The risk of wind damage was used as a model where an apparent gap between stated accepted risk and extent of risk‐reducing measures taken among south Swedish non‐industrial private forest owners was used as a starting point. The results of an enquiry, and personal experiences from the debate after an extensive wind damage event in January 2005, were used and complemented study of literature. It was concluded that risks have not been particularly actively managed in the Swedish forestry culture. This was explained by notions of seeing (i) risks such as wind damage as a natural hazard rather than a technological risk that can be modulated, and (ii) forestry as an enterprise free of valuation in which value aspects of risk were neglected. A narrow agenda in Swedish forest research influenced the risk management policy, where forest consultants played an important role as a link between science and practice and between the public and the private. Neither the legislator nor the forestry consultants declared how they weighted risk which reduced the fulfilment of goals. At the national level relaxation of regulations after 1993 has not yet resulted in markedly diversified privately owned forests and spreading of risk as intended, and the management of the risk of wind damage before January 2005 was in many cases not adapted to the risk the individual forest owner was prepared to take. The results were discussed with respect to possibilities for improved fulfilment of goals in Swedish forestry by facilitating more active risk management.

Pervasive growth reduction in Norway spruce forests following wind disturbance.

Background In recent decades the frequency and severity of natural disturbances by e.g., strong winds and insect outbreaks has increased considerably in many forest ecosystems around the world. Future climate change is expected to further intensify disturbance regimes, which makes addressing disturbances in ecosystem management a top priority. As a prerequisite a broader understanding of disturbance impacts and ecosystem responses is needed. With regard to the effects of strong winds – the most detrimental disturbance agent in Europe – monitoring and management has focused on structural damage, i.e., tree mortality from uprooting and stem breakage. Effects on the functioning of trees surviving the storm (e.g., their productivity and allocation) have been rarely accounted for to date. Methodology/Principal Findings Here we show that growth reduction was significant and pervasive in a 6.79·million hectare forest landscape in southern Sweden following the storm Gudrun (January 2005). Wind-related growth reduction in Norway spruce (Picea abies (L.) Karst.) forests surviving the storm exceeded 10% in the worst hit regions, and was closely related to maximum gust wind speed (R2 = 0.849) and structural wind damage (R2 = 0.782). At the landscape scale, wind-related growth reduction amounted to 3.0 million m3 in the three years following Gudrun. It thus exceeds secondary damage from bark beetles after Gudrun as well as the long-term average storm damage from uprooting and stem breakage in Sweden. Conclusions/Significance We conclude that the impact of strong winds on forest ecosystems is not limited to the immediately visible area of structural damage, and call for a broader consideration of disturbance effects on ecosystem structure and functioning in the context of forest management and climate change mitigation.

Models of low temperature and high irradiance and their application to explaining the risk of seedling mortality

Low temperature during the growing season is known to be a leading cause of stress and damage to tree seedlings and interactive effects with high irradiance have been recognised as enhancing the damage. Spatial variation in low temperature and irradiance for mountainous terrain was, therefore, hypothesised to give rise to spatially variable potential for regeneration of tree seedlings and expansion of forest. Combined exposure to low temperature and high irradiance appears most likely on clear mornings following frosty nights. Geographic information system-based models of the spatial variation in minimum air temperature over clear-felled terrain and potentially intercepted direct radiation energy were constructed and were used together with measured values of minimum air temperature to explain observed spatial variation in mortality rates for planted tree seedlings in central Sweden. A local-scale multiple regression model explained 78% of the measured spatial variability in minimum air temperature over 625 km 2 and a corresponding, but univariate, microscale model explained 54% of the measured spatial variation in minimum air temperature over 4 ha. Multiple logistic regression models for the mortality rates of seedlings showed there was no significant effect of potentially intercepted amounts of direct radiation energy during the morning for either scale. There was, however, a significant effect (p<0.0001) of measured minimum air temperature on seedling mortality rates for the microscale study, but no corresponding significant effect for the local-scale study. This confirms that low temperature is an important determinant for seedling mortality. It is likely that other factors than low temperature may be important. However, our results indicate that effects of local-scale variability in minimum air temperature, represented by the minimum air temperature at standard height above the ground (1.8 m), may be over-shadowed by minimum air temperature variability at seedling height in complex terrain. This has implications for the use of standard meteorological data for studies into the responses of plants to abiotic factors.

Are forest disturbances amplifying or canceling out climate change-induced productivity changes in European forests?

Recent studies projecting future climate change impacts on forests mainly consider either the effects of climate change on productivity or on disturbances. However, productivity and disturbances are intrinsically linked because 1) disturbances directly affect forest productivity (e.g. via a reduction in leaf area, growing stock or resource-use efficiency), and 2) disturbance susceptibility is often coupled to a certain development phase of the forest with productivity determining the time a forest is in this specific phase of susceptibility. The objective of this paper is to provide an overview of forest productivity changes in different forest regions in Europe under climate change, and partition these changes into effects induced by climate change alone and by climate change and disturbances. We present projections of climate change impacts on forest productivity from state-of-the-art forest models that dynamically simulate forest productivity and the effects of the main European disturbance agents (fire, storm, insects), driven by the same climate scenario in seven forest case studies along a large climatic gradient throughout Europe. Our study shows that, in most cases, including disturbances in the simulations exaggerate ongoing productivity declines or cancel out productivity gains in response to climate change. In fewer cases, disturbances also increase productivity or buffer climate-change induced productivity losses, e.g. because low severity fires can alleviate resource competition and increase fertilization. Even though our results cannot simply be extrapolated to other types of forests and disturbances, we argue that it is necessary to interpret climate change-induced productivity and disturbance changes jointly to capture the full range of climate change impacts on forests and to plan adaptation measures.

Decision Support for Active Risk Management in Sustainable Forestry

Abstract Active risk management is central to the implementation of sustainable forestry, yet a fairly unexplored field of research. This study attempts to present some components of an analytical framework for risk management centred on the decision situation. Within this framework, a systems analysis approach to providing decision support for risk management is presented with an example dealing with outcome risk. The approach covers identification of risk factors for which decision support could be useful for the problem holders, presentation of how one such risk factor, wind damage, can be characterised in terms of a computer model, and how this computer model can be used for providing decision support. In addition to outcome risk, there is risk due to knowledge uncertainty and uncertainty related to valuation. The implications of these uncertainties for active risk management are discussed. Furthermore, communicative criteria for making the decision support useful are discussed. Since the work on the concept is still under way, this is too early to evaluate. So far, however, our results have been met with interest not only from representatives of forestry but also from mass media.

Productivity scenarios for the Asa Forest Park

The primary focus of the SUFOR research programme was the Asa Royal Forest Park, 33 km2 in size, in which the Asa Forest Research Park 12 km2 in size, is included. A field station of the Swedish Agricultural University is located in the park, which was expropriated from its German owner in 1945 and become a Royal domain. The area is host to a number of research projects and conditions for synergistic cooperation is good. Technicians from the station assisted in sampling and data collection. Various parameters of the area are shown in Tab. 14.2. The park borders to Lake Asa, the majority of the area being found on the western side of the lake. A map of the area is shown in Fig. 13.1. The park is located 40 km north of the city of Vaxjo in the province of Smaland. Forestry in the area is traditional conifer forestry, representing the point of departure for any future changes. In the past, the original forest cover in Asa was a mixed deciduous forest dominated by lime (Tilia) and alder (Alnus), and also containing European beech (Fagus sylvatica), Scots pine (Pinus sylvestris), oak (Quercus robur) and birch (Betula). Farming on the shores of the lake started around 1200 AD and Norway spruce entered the landscape on a small scale around 1600. Mixed deciduous vegetation dominated until clearance of the land by farmers from about 1700 onwards. After 1840, Norway spruce increased markedly through colonization and through planting on land that had been abandoned after large numbers of emigrants went to America. Small crofts and farms were reforested, a process that in the province of Smaland continued as a result of urbanization from about 1930 on until the present day. From now on conifers, and Norway spruce in particular, are dominant.

Life-style services and yield from south-Swedish forests adaptively managed against the risk of wind damage: a simulation study

We estimated the effect of adapting forest management to reduce the risk of wind damage under climate change on life-style services and forest yield in a south-Swedish forest using an integrated modelling approach. The ECHAM5/CCLM models had been used to produce a reference climate and a climate change scenario for the A1B emission scenario. Using the FinnFor model we estimated the effect of the climate change scenario on the site index for three common commercial tree species for the period 2001–2100. The adjusted site index was applied in projections of the forest using the Forest Time Machine model. The WINDA-GALES model was used to calculate the probability of wind damage in simulated future states of the forest. Effects of increasing forest owner motivation to take measures to adapt to climate change were simulated by comparing the effects of introducing adaptive measures in years 2001 and 2051, respectively. These adaptive measures had been identified in consultation with stakeholders. In the simulations, adaptive regimes resulted in generally increased yield, increased hunting potential and a higher number of forest management operations to be carried out, although other aspects of recreation services were reduced. The net return remained unaffected by most of the adaptive forest management regimes. The simulations were made without accounting for effects of predicted wind damage on the states of the forest. Forest owners perceiving increased risk of wind damage but also risk to their life-style would have to balance adaptive measures between these risks. We conclude that adapting forest management to reduce the risk of wind damage may impact on life-style services. Hence, this may affect the process of adaptation to an increasing risk of wind damage in southern Sweden.