How much management is enough? Stakeholder views on forest management in fire-prone areas in central Portugal

With the increasing pressure to improve the contribution of forests to help dealing with global changes, it is critical to understand the different perceptions of those involved in the forest. How do forest owners, managers and members of local communities who often depend on the forest, value it and what are the problems affecting the forests in terms of being able to meet these new challenges?In Portugal, this task has taken on an even greater priority as more than 90% of the forest is private and forest management relies on the individual decisions of thousands of forest owners. To understand stakeholder views on forest and forest management, a transversal social perception survey was implemented in the form of a case study of central Portugal which included decision-makers, local technicians, forest owners and the general public.The results show that there is a consensus on the main issues affecting forests and forest management. A shift from classic forest owners to the emergence of indifferent forest owners was observed, although this shift has not been recognized by the forest owners in the survey, who maintain the individual management of their properties.     

Complexity in modelling forest ecosystems: How much is enough?

The levels-of-integration concept in ecology suggests that while the population and community levels of biological organization provide understanding, they do not provide an adequate basis for predicting future states of populations, communities or ecosystems. Empirical models of populations and communities are implicitly ecosystem level because they are based on measures of the results of all past determinants that affected the populations and communities in question. They can be good predictors under unchanging conditions, but they are not able to predict for changing conditions, which requires the explicit representation of those ecological processes that are anticipated to change. The question addressed in this paper is: how does the performance of a “simple” stand-level model change as representations of these processes are added, and how much complexity is enough? Examples are given of change in performance of the ecosystem management model FORECAST run as a light competition model as nutrient regulation of growth and understory interactions are added singly or in combination. These examples are framed in comparisons of simulations for a white spruce stand in the in boreal mixedwood region in northern British Columbia, for a long-term thinning-fertilization trial in a Douglas-fir stand on southern Vancouver Island, and for yield decline in Chinese fir in south eastern China. It is concluded that the effect of adding complexity on the predictions of this model depends on the time scale of the simulation and the management or natural disturbance regime that is being simulated. The results supported Occam's razor: that models should be as simple as possible but as complex as necessary.     

Do forest policy actors learn through forward-thinking? Conflict and cooperation relating to the past,present and futures of sustainable forest management in Germany

Collaborative participatory policy approaches based on foresight methodology have recently been proposed as promising governance tools to achieve sustainability in general, and address and manage challenges of integrating competing demands on forest land use (e.g., timber production, nature protection, recreation) in particular. Their main argument is that participatory processes will bring policy actors together. Based on long- and short-term future-oriented thinking and actions, they will overcome their previous value-laden and interest-based conflicts through informed communication, deliberation, policy learning and mutual cooperation. But do policy actors learn when they are thinking, debating and shaping the ‘forest futures’ they want to achieve or avoid? To what extent are current beliefs, values, worldviews, and conflict structures projected onto the future? What are their impacts on policy learning today?This paper addresses these research questions from a knowledge-based perspective of relevant policy learning theories. We trace changes and stability in beliefs, values (perception) and behavior (cooperation/conflict) among the involved policy actors. We assess to what extent future-oriented thinking and discussions contribute to, or inhibit, policy learning today.Empirically, the paper is informed by three case studies of regional ‘forest futures’ processes in Germany. They include forest landscapes in Upper Palatinate and South of Munich in Bavaria, and the Black Forest National Park in Baden-Württemberg. They represent different cases in terms of levels of stakeholder conflicts, integrative/segregative forest land use approaches, and the rural/urban divide. The paper is based on a qualitative analysis of interviews and documents about past and future forest land use, and observation of participatory scenario-building and back-casting workshops during 2011–2014.In our analysis, we found that forest policy actors adhered to their pre-existing beliefs and remained divided in terms of present and future aspects of sustainable forest management. That is, we observed no substantial or only strategic policy learning among the involved policy actors. We explain these findings in terms of competing actors' belief systems and worldviews that lead to competing understandings and expectations of ‘forest futures’. We discuss our research against the theoretical propositions and in view of the state-of-the art. We draw conclusions relevant for scholars and policymakers interested in collaborative policy learning processes, and suggest possible topics for further research.     

How well does Kirtland's warbler management emulate the effects of natural disturbance on stand structure in Michigan jack pine forests?

Jack pine (Pinus banksiana) forests in parts of northern Lower Michigan have been managed with 30 years of extensive clearcut harvesting followed by planted stand establishment in order to maintain habitat for the endangered Kirtland's warbler (Dendroica kirtlandii). We used two, parallel chronosequences to study how this management has affected the structural development of jack pine stands relative to the historically dominant disturbance regime of stand-replacing wildfire. Each chronosequence consisted of three young stands (age range 3–6 years), three intermediate-aged stands (age range of 12–17 years) and three mature stands (age range of 39–69 years). Average stem density in young plantations (2300 stems/ha) was lower than the average for young, fire-origin stands (11,000) and varied over a much narrower range among stands (1403–2667 for plantations and 1552–24,192 in fire stands). In addition, within-stand patchiness of stem density was also much higher in the wildfire sites for young and intermediate ages. Plantation sites possessed very little dead wood at young ages (averaging 3 snags/ha and 12 m³/ha CWD) compared to young fire-origin stands (averaging 252 snags/ha and 49 m³/ha CWD). In contrast, mature plantations had similar levels of dead wood (averaging 269 snags/ha and 22 m³/ha CWD) as mature fire-origin stands (averaging 557 snags/ha and 12 m³/ha CWD). Differences between the plantation and fire-origin chronosequences were driven mainly by young- and intermediate-aged stands, whereas mature stands were typically quite similar in all structural features. Our results show clearly that forest management aimed at preserving and enhancing the population of a single endangered species results in greatly simplified habitat structure at the stand level, and suggest that this simplification is perpetuated across the landscape as well. Of particular concern are the effects of extensive harvesting and planting on the availability of snags and CWD.     

Low rates of pollen contamination in a Scots pine seed orchard in Sweden: the exception or the norm?

We investigated mating structure and gene flow in a clonal seed orchard of Scots pine (Pinus sylvestris L.) over three consecutive pollination seasons (2010–2012) with nine nuclear microsatellite markers. The paternity of 1991 offspring from four maternal parents was assigned to 28 candidate fathers using an exclusion procedure and a likelihood-based method implemented in the program CERVUS. Relative reproductive success was highly variable among pollen parents but consistent across years and ranged from 0.1% to 18.3%. Consequently, the seed crops’ effective number of fathers was reduced to 52.9%, 48.8%, and 45.7% of the census in the three seasons, respectively. Self-fertilization fluctuated around the orchard's expected value of 5.1%, reaching 4.05%, 7.71%, and 6.61%, respectively. Pollen contamination was estimated to be 5.64%, 7.29%, and 4.89%, respectively, after correction for cryptic gene flow. CERVUS provided similar results as the exclusion method, but estimates greatly varied depending on the input parameters, mainly the proportion of fathers sampled. These results indicate the studied seed orchard is a well-functioning production population with only minor negative effects of self-fertilization and pollen contamination on the quality of seed crops. Genotyping issues associated with microsatellites as a potential source of false paternity assignment and exclusion are discussed.     

Sustainability as a guideline for strategic planning? The problem of long-term forest management in the face of uncertainty

Forest management, which is the main focus of this paper, is facing fundamental paradoxes and dilemmas that cannot be addressed by long-term management strategies or management concepts, even where the intention of these strategies is to follow a sustainability path. On this basis, it is argued that sustainability is not a suitable future-oriented term but rather a term oriented towards the present. The more complex the relationships between the different social subsystems, the more rapid the social change of modern societies, the more confusing the present situation and the more unpredictable the future, the less suitable utopian, long-term strategies and the attitude and strategy of firm decisiveness are to address challenges. Several suggested management strategies and techniques such as incrementalism, adaptive management and scenario-analysis are critically discussed. The intention of these strategies is to cope with uncertainty and ignorance. With regard to their limitations, it can be concluded that strategic decisions in the face of uncertainty have to explicitly consider the reversibility of decisions and the awareness of their shortcomings in relation to various dimensions of risk, uncertainty and ignorance. It is therefore necessary to look for modes of planning that actively address uncertainty in organizing learning opportunities and permanent feedback control.     

Tree-ring Δ13C reveals the impact of past forest management on water-use efficiency in a Mediterranean oak coppice in Tuscany (Italy)

? The effects of thinning and heavy stand density reduction was investigated in Turkey oak (Quercus cerris L.) forests of central Italy, to evaluate the physiological responses and the growth status of trees that survived a past coppice cut and thinning to convert the stand to high-forest.

? The working hypothesis was that a strong decrease in stand density would cause a decreasing in canopy-intrinsic water-use efficiency (measured as the ratio of CO₂ assimilation to stomatal conductance, A/g), thus an increase in tree-ring carbon isotopic discrimination (Δ¹³C).

? The tree-ring Δ¹³C of the remaining trees (“survivors”) was found to have significantly (P < 0.05) raised between year two and year seven since the coppice stand was thinned (high-forest conversion thinnings). This effect was mostly caused by a large decrease in tree-rings Δ¹³C at control site which was characterized by high density and competition by trees. An increase in survivors tree-rings Δ¹³C probably indicates an improved water availability, possibly induced by a decrease in competition and in stand density or a decrease in the precipitation intercepted by the canopy (i.e., a stronger increase in g over A since a decrease in A is highly unlikely). A change in foliar nitrogen, foliar Δ¹³C and content in chlorophylls was also recorded seven years after thinning.

? Thinnings carried out to convert old abandoned coppices into high-forest stands induce short-term stimulation of Turkey oak growth by increasing light and water availability. We were able to make a detailed reconstruction of the impact of past silvicultural treatment on the stand using a tree-ring wood Δ¹³C time-series.

     

Open woodland in Europe in the Mesolithic and in the Middle Ages: Can there be a connection?

In Grazing Ecology and Forest History F.W.M. Vera published his hypothesis that Europe's primeval vegetation was not closed forest but a more open, park-like landscape maintained by the grazing of large herbivores. The palaeoecological evidence has been re-examined a number of times, however, Vera's research and conclusions about more recent periods (ca. 500–1900 a.d.) have so far been neglected. These, nonetheless, are equally significant elements in the testing of the hypothesis, and deserve to be evaluated. It is argued in this paper that historical sources could be used in testing the hypothesis; however, analysis should concentrate on particular areas and periods and derive a synthesis from these. Vera mixes sources from many regions and periods in the same analysis, which therefore does not provide useful information about the hypothesis. Furthermore, Vera's analysis is based on the assumption that early medieval written sources depict a landscape that is in direct connection with the pre-Neolithic open vegetation, although in some early medieval landscapes domestic animals replaced the original large herbivores. He also claims that medieval coppices were formed straight out of this primeval vegetation. However, current landscape archaeological research shows that areas unaffected by human activity were virtually non-existent in the European lowlands by the Early Middle Ages, therefore early medieval Royal Forests and high medieval coppices were not formed out of primeval ‘wilderness.’ Because there is no direct connection between pre-Neolithic and medieval landscapes – although they can be analogous – the historical ecological evidence in Grazing Ecology and Forest History is irrelevant to the hypothesis. The hypothesis could only be tested if it were first proved that at a particular place the pre-Neolithic vegetation survived until the Early Middle Ages.     

Challenges in developing and implementing a decision support systems (ETÇAP) in forest management planning: a case study in Honaz and Ibradı, Turkey

Decision support systems (DSSs) are indispensable tools in preparing a forest management plan for a better combination of multiple forest values. This study attempted to develop and explain a stand-based forest management DSS (Ecosystem-based multiple-use forest planning [ETÇAP]) comprising a traditional simulation, linear programming (LP), metaheuristics and geographic information system. The model consists of five submodels; traditional management approach to handle inventory data, an empirical growth and yield model, a simulation to conceptualize management actions, a LP technique to optimize resource allocation and a simulated annealing approach to directly create a spatially feasible harvest schedule. The ETÇAP model has been implemented in a comparative two case study areas; Denizli–Honaz and Akseki–Ibrad?. Both simulation and optimization models outperformed to the traditional management plan. The periodical change of growing stock, allowable cuts, carbon sequestration and water production are used as performance indicators. The results showed that more amount of wood could be harvested over time compared to traditional level of harvesting. It could be concluded that various management strategies allowed managers to stimulate more decision options for better outputs through intertemporal trade-offs of management interventions as the model provided tools to quantify forest dynamics over time and space. Challenges exist to establish the functional relationships between forest structure and values for better quantification and integration into the management plans.     

Born to be a forest owner? An empirical study of the aspects of psychological ownership in the context of inherited forests in Finland

Ownership is a multidimensional phenomenon that includes legal, social, and emotional aspects. In addition to legal aspects, the social and emotional aspects, “feelings of ownership,” potentially have behavioral effects. Nevertheless, these aspects are often overlooked in the research influencing the forest owners' behavior and thus their forest management decisions. This article examines how private forest owners with inherited forest holdings construct feelings of ownership toward their forests and how these constructions are reflected in their forest management decisions. Forest ownership is addressed through the theory of psychological ownership. On the basis of 15 thematic in-depth interviews, we suggest that a sense of identity and control, as dimensions of psychological ownership, can influence whether forest management decisions are guided by tradition, economic incentives, or responsibility toward property. Based on the results, a forest owner typology (restricted, indifferent, informed, and detached forest owners) was constructed, further enabling us to understand the differences among private forest owners and the roots of their forest management decisions. More generally, the study highlights the important role of emotions in forest management decisions.     

Does forest biomass harvesting for energy reduce fire hazard in the Mediterranean basin? a case study in the Caroig Massif (Eastern Spain)

The Mediterranean basin is a fire-prone area and is expected to continue being so according to projected climate and socioeconomic changes. Sustainable exploitation of forest biomass could have a positive effect on wildfire hazard mitigation. A modelling approach was used to compare how four different Scenarios for biomass collection for energy use affect fire behaviour and potential burnt area at landscape level under extreme meteorological conditions in a typical Mediterranean Massif. A case study of Pinus halepensis stands in Valencia (Eastern Spain) was conducted. The FARSITE simulator was used to evaluate the burnt area and fire behaviour parameters. Simulations predicted a significant increase in the burnt area and the values of most fire behaviour parameters in a Scenario of rural abandonment, relative to the current situation. Biomass management through thinning reduced canopy bulk density; however, no differences in the values of the main fire behaviour parameters were detected. Thinning and understory clearing, including biomass collection in large shrub fuel model areas, significantly reduces fire hazard. Forest biomass sustainable harvesting for energy is expected to reduce fire hazard if management includes intense modification of fuel models, comprising management of shrub biomass at the landscape level. Strong modification of forest fuel models requires intensive silvicultural treatments. Therefore, forest biomass collection for energy in the Mediterranean basin reduces fire hazard only if both tree and shrub strata are managed at landscape level.     

Covariation between plant biodiversity and soil systems in a European beech forest and a black pine plantation: the case of Mount Faito,(Campania,Southern Italy)OA

Both climate and land-use changes, including the introduction and spread of allochthonous species, are forecast to affect forest ecosystems. Accordingly, forests will be affected in terms of species composition as well as their soil chemical and biological characteristics. The possible changes in both tree cover and soil system might impact the amount of carbon that is stored in living plants and dead biomass and within the soil itself. Additionally, such alterations can have a strong impact on ...     

Unraveling the tripartite interactions among the woolly poplar aphid,its host tree,and their environment: a lead to improve the management of a major tree plantation pest?

Key message

For an optimal deployment of poplar resistance to the gall-inducing aphid Phloeomyzus passerinii , a laboratory susceptibility assay has been developed. The nature of aphid–tree interactions during compatible and incompatible situations has been studied in detail. This should help at identifying specific resistance markers and at testing effects of site conditions on tree–pest interactions.

Context

P. passerinii is a major pest of poplar plantations in Europe, and the plantation of resistant poplar genotypes is regarded as the best long-term management strategy for this pest. This requires a sound knowledge of the interactions among the pest, its host and their environment.

Aims

Here, we review the recent advances aiming at developing an optimal deployment of host resistance versus P. passerinii.

Results

Investigations on aphid-host interactions demonstrated that P. passerinii induces pseudogalls within the bark of susceptible hosts. This results in a reduction of starch bark content during aphid outbreaks, which could be involved in tree death. The constitutive level of starch in the bark could be related to the tolerance level of trees. A susceptibility test has been designed for poplar genotypes, discriminating three categories of susceptibility depending on tree’s ability to totally or partially inhibit pseudogall induction. The test still has several limitations however. It neither takes into account the large level of individual genetic diversity of the aphid in France, nor the environmental modulation of tree resistance and tolerance, while water deficit and fertilization could potentially affect these parameters.

Conclusion

The hypotheses drawn regarding the processes leading to tree death or resistance should help at identifying resistance markers, and at testing effects of site conditions on tree–pest interactions.

     

Are small-scale overstory gaps effective in promoting the development of regenerating oaks (Quercus ithaburensis) in the forest understory?

We investigated the effect of small-scale overstory gaps on the ecophysiology and growth of Quercus ithaburensis saplings. The study aim was to characterize how changes in daily exposure to direct beam radiation affect photosynthetic performance in the short term and growth and biomass partitioning in the long term. Using individual net-houses, the following treatments were applied: (a) Unshaded (daily irradiance = 100 %), (b) shading net with no gap (Shade-daily irradiance = 6 %), (c) shading net with 1 h gap allowing direct beam radiation (11:00 am–12:00 pm, Shade+1-irradiance = 20 %), (d) shading net with 3 h gap (11:00 am–2:00 pm, Shade+3-irradiance = 44 %). The experiment was performed in an irrigated field. We measured growth, biomass allocation, leaf traits, daily courses of leaf gas exchange and water potential. Oak dry-weight increased while height to dry-weight ratio and specific leaf area decreased with increasing daily exposure to direct beam radiation. Leaf chlorophyll content was less affected. Higher net carbon assimilation rates (A), stomatal conductance (gs) and A/gs were associated with higher instantaneous photosynthetic photon flux density (PPFD) throughout the entire experimental PPFD range. However, during gap-hours, while exposed to saturating radiation levels of similar level (ca. 1,800 µmol photon m^?2 s^?1), A in the Shade+1 oaks was about half that of the Shade+3 oaks and nearly one-third that of the Unshaded oaks. Patterns of gs, intercellular CO₂ (Ci) and quantum efficiency of photosystem II pointed towards the possibility of a metabolic limitation. In conclusion, oaks benefited significantly from small scale overstory gaps though their capacity to utilize transient saturating radiation levels decreased with decreasing gap duration.     

Living without herbicides in Qu��bec (Canada): historical context, current strategy, research and challenges in forest vegetation management

Vegetation management is crucial to meeting the objectives of forest plantations. Following public hearing processes, chemical herbicides were banned on Crown forest lands in Québec (Canada) in 2001. Release now mainly relies on mechanical treatments. Our objectives are to review the historical context and the research conducted over the past 15 years that has led to the province??s current vegetation management strategy and to identify the major challenges of vegetation management being faced in Québec in the context of intensive silviculture and ecosystem-based management. Research has led to an integrated management model without herbicides, adapted to the ecological characteristics of reforestation sites. The Québec experience illustrates how, on most sites, vegetation management that is based on early reforestation, the use of tall planting stock and intensive mechanical release brings crop trees to the free-to-grow stage without the use of herbicides and without resulting in major effects on vegetation diversity. This vegetation management strategy is an asset in the implementation of ecosystem-based management. However, research demonstrates that mechanical release alone does not promote optimal crop-tree growth, due to rapid resprouting or suckering of competitors and competition from herbaceous species. Therefore, the current strategy poses important challenges in the management of plantations where the objective is to maximise wood production.     

China's role in the global forest sector: how will the US recovery and a diminished Chinese demand influence global wood markets?

Over the last decade, while the size of China's economy more than doubled, China has simultaneously become a major producer and exporter of forest products. Although China's domestic supply of wood is significantly constrained both by a limited natural supply and by conservation-oriented policies, the country is increasingly regarded as the world's “wood workshop.” Furthermore, China is the largest driver of demand for the trade in tropical logs and is becoming a significant driver of demand for trade in coniferous logs. In this paper, we describe a spatial equilibrium model adapted to study forest sector markets and policies that affect them. We present the model and the result of two alternative future scenarios. The first scenario analyzes the impact on global forest products markets of a US recovery in wood markets. The second scenario examines the effect on global forest products markets of decelerating growth in Chinese demand for wood products. Through these two scenarios, the modeling output sheds light on the role China's wood products markets have on resource supply and trade around the world. The trade model shows substantial potential changes in global prices, production, and trade activity associated with the recovery in domestic demand in the USA.     

Spatial variability of nutrient stocks in the humus and soils of a forest massif (Fougères, France)

In this study, the spatial distribution of nutrient stocks (K, Ca, Mg and P) was examined in humus and soils at the forest massif scale (Fougères forest, France). A random stratified sampling plan including 100 sampling points was used and three potential variation factors of nutrient stocks were tested: age of stand, type of stand (broad-leaved or coniferous trees) and type of soil. Sampling classes were then compared and the variation factors were examined. Results demonstrated that nutrient stocks in the humus were not influenced by the cited factors and only the type of soil influenced nutrient stocks in soils. In fact, stocks of exchangeable elements in soils were much higher in Colluviosols-Fluviosols which show redoximorphic characteristics, and available phosphorus stocks were lower than in Alocrisols-Neoluvisols. Moreover, a low variability of nutrient stocks was observed in Alocrisols-Neoluvisols as opposed to Colluviosols-Fluviosols, which may suggest the existence of other variation factors not taken into account in this study (hydromorphic gradient, type and age of stand in hydromorphic zones).     

Ontogenetic changes in water-use efficiency (δC) and leaf traits differ among tree species growing in a semiarid region of the Loess Plateau,China

On the Loess Plateau, China, several planted tree species such as Populus hopeinsis and Robinia pseudoacacia suffer occasional diebacks in the top shoots, reducing growth rates after maturation. However, this does not usually occur in other species, e.g., Ulmus pumila and Zizyphus jujuba. We compared stable carbon isotope ratios (δ¹³C) as indicators of leaf water-use efficiency (WUE), leaf mass per unit area (LMA), and leaf area- and mass-based nitrogen content (N_area and N_mass) by tree height (1, 5, and 10 m) in P. hopeinsis, R. pseudoacacia, U. pumila, and Z. jujuba. In P. hopeinsis and R. pseudoacacia, leaf δ¹³C and N_area were significantly lower in 10-m trees than in 1-m saplings, indicating that leaf WUE and photosynthetic rates of both species decreased with tree height. In contrast, δ¹³C in Z. jujuba varied little with tree height. The δ¹³C of 10-m-tall U. pumila trees was significantly higher than that of 1-m plants, demonstrating an increase in WUE with tree height. Decreasing WUE, leaf N_area, and N_mass with height increases in P. hopeinsis and R. pseudoacacia may be related to water and nutrient limitations for these species in semiarid regions. In contrast, stable or increasing δ¹³C with tree height in U. pumila and Z. jujuba may account (to some extent) for successful production of these species under identical environmental conditions. Diameter growth rate also decreased with maturity in P. hopeinsis and R. pseudoacacia, but increased or was stable for U. pumila and Z. jujuba. The differences in leaf WUE and LMA among species with tree maturity may be related to species’ growth patterns and susceptibility to drought stress, and are likely to be important new criteria for plantation species selection on the Loess Plateau.