Concentrating anthropogenic disturbance to balance ecological and economic values: applications to forest management

More future synergies and less trade-offs between forest ecosystem services with natural climate solutions instead of bioeconomy solutions

To reach the Paris Agreement, societies need to increase the global terrestrial carbon sink. There are many climate change mitigation solutions (CCMS) for forests, including increasing bioenergy, bioeconomy, and protection. Bioenergy and bioeconomy solutions use climate-smart, intensive management to generate high quantities of bioenergy and bioproducts. Protection of (semi-)natural forests is a major component of "natural climate solution" (NCS) since forests store carbon in standing biomass and soil. Furthermore, protected forests provide more habitat for biodiversity and non-wood ecosystem services (ES). We investigated the impacts of different CCMS and climate scenarios, jointly or in isolation, on future wood ES, non-wood ES, and regulating ES for a major wood provider for the international market. Specifically, we projected future ES given by three CCMS scenarios for Sweden 2020-2100. In the long term, fulfilling the increasing wood demand through bioenergy and bioeconomy solutions will decrease ES multifunctionality, but the increased stand age and wood stocks induced by rising greenhouse gas (GHG) concentrations will partially offset these negative effects. Adopting bioenergy and bioeconomy solutions will have a greater negative impact on ES supply than adopting NCS. Bioenergy or bioeconomy solutions, as well as increasing GHG emissions, will reduce synergies and increase trade-offs in ES. NCS, by contrast, increases the supply of multiple ES in synergy, even transforming current ES trade-offs into future synergies. Moreover, NCS can be considered an adaptation measure to offset negative climate change effects on the future supplies of non-wood ES. In boreal countries around the world, forestry strategies that integrate NCS more deeply are crucial to ensure a synergistic supply of multiple ES.

Producing wood at least cost to biodiversity: integrating Triad and sharing-sparing approaches to inform forest landscape management

Forest loss and degradation are the greatest threats to biodiversity worldwide. Rising global wood demand threatens further damage to remaining native forests. Contrasting solutions across a continuum of options have been proposed, yet which of these offers most promise remains unresolved. Expansion of high-yielding tree plantations could free up forest land for conservation provided this is implemented in tandem with stronger policies for conserving native forests. Because plantations and other intensively managed forests often support far less biodiversity than native forests, a second approach argues for widespread adoption of extensive management, or 'ecological forestry', which better simulates natural forest structure and disturbance regimes - albeit with compromised wood yields and hence a need to harvest over a larger area. A third, hybrid suggestion involves 'Triad' zoning where the landscape is divided into three sorts of management (reserve, ecological/extensive management, and intensive plantation). Progress towards resolving which of these approaches holds the most promise has been hampered by the absence of a conceptual framework and of sufficient empirical data formally to identify the most appropriate landscape-scale proportions of reserves, extensive, and intensive management to minimize biodiversity impacts while meeting a given level of demand for wood. In this review, we argue that this central challenge for sustainable forestry is analogous to that facing food-production systems, and that the land sharing-sparing framework devised to establish which approach to farming could meet food demand at least cost to wild species can be readily adapted to assess contrasting forest management regimes. We develop this argument in four ways: (i) we set out the relevance of the sharing-sparing framework for forestry and explore the degree to which concepts from agriculture can translate to a forest management context; (ii) we make design recommendations for empirical research on sustainable forestry to enable application of the sharing-sparing framework; (iii) we present overarching hypotheses which such studies could test; and (iv) we discuss potential pitfalls and opportunities in conceptualizing landscape management through a sharing-sparing lens. The framework we propose will enable forest managers worldwide to assess trade-offs directly between conservation and wood production and to determine the mix of management approaches that best balances these (and other) competing objectives. The results will inform ecologically sustainable forest policy and management, reduce risks of local and global extinctions from forestry, and potentially improve a valuable sector's social license to operate.

A Quantitative Analysis of Surface Changes on an Abandoned Forest Road in the Lejowa Valley (Tatra Mountains, Poland)

The main aim of this research was to determine the magnitude of geomorphologic changes within a section of a forest road. The research was carried out in the Lejowa Valley in the Tatra Mountains. The measurements of the surface of the road were performed using a RIEGL VZ-4000 terrestrial laser scanner (TLS). TLS models for 2017, 2018, and 2019 served as the basis for the determination of quantitative and spatial relief transformations. The net annual change on the studied road within the first period equaled −884 m3 ha−1 year−1, and for the second period −370 m3 ha−1 year−1. Changes across the accumulation fan ranged from −265 m3 ha−1 year−1 to +36 m3 ha−1 year−1. The average rate of erosion on the studied abandoned road is similar, and sometimes even greater than that on roads which are still in use. Our research shows that improper road location may lead to irreversible changes to the natural environment. The planning of a forest road must take into account natural conditions, otherwise progressive relief transformations may lead to significant surface changes and the road may be excluded from use.

Conservation and production responses vary by disturbance intensity in a long-term forest management experiment

Reductions in management intensity are often proposed to support a broader range of beneficial ecosystem responses than traditional management approaches. However, few studies evaluate ecosystem responses across approaches. Also, managers lack information about how species traits mediate responses across management approaches, a potentially substantial source of spatial and temporal variation in population and community responses that if ignored may hinder effectiveness of management programs. We used data collected over eight years from a manipulative experiment to test how four forest management strategies influenced avian community composition and wood production. After harvesting, we evaluated responses to three levels of plant cover suppression (Light, Moderate, and Intensive herbicide applications) in relation to a control without herbicide. We predicted the Moderate and Intensive treatments would exert strong negative effects on leaf-gleaning insectivores, including species of conservation concern due to long-term population declines. However, given high forest productivity, we expected temporal duration of effects to be short. Richness of leaf-gleaning bird species was reduced by 20-50% during the first four years post-harvest (when herbicide treatments were on-going), but the effect size declined over the next four years once treatments were completed (13-20% reduction). Effect sizes were substantially smaller for the non-leaf-gleaner group during years 1-4 (19-27%) and disappeared during years 5-8 (2-3%). However, in our final year of observation, we did find an average of five fewer non-leaf-gleaner species on Light vs. Control units. In the last two years of observation, turnover probabilities for the leaf-gleaner species remained higher on all treatments compared to the Control (0.11-0.21), indicating that new species continued to colonize treatments. Planted conifers were 40-44% taller and 74-81% larger in diameter in the Moderate and Intensive treatments compared to the Control, leading to substantial gains in wood biomass. Current practices provided more balance between two ecosystem responses, avian diversity and wood production, compared to less intensive alternatives. When short-term negative effects occur, the spatial distribution of harvesting and regeneration regionally indicates that habitat is often available locally to support leaf-gleaning and non-leaf-gleaning bird populations while releasing other portions of the region for high priority conservation objectives including late-successional forest reserves.

The evolutionary species pool concept does not explain occurrence patterns of dead-wood-dependent organisms: implications for logging residue extraction

Emulation of natural disturbances is often regarded as a key measure to make forestry biodiversity-oriented. Consequently, extraction of logging residues is assumed to have little negative effect in comparison to extraction of dead wood mainly formed at natural disturbances. This is consistent with the evolutionary species pool hypothesis, which suggests that most species are evolutionary adapted to the naturally most abundant habitats. We tested this hypothesis for dead-wood-dependent macrofungi, lichens, and beetles in a boreal forest landscape in central Sweden, assuming that species are adapted to conditions similar to today’s unmanaged forest. No occurrence patterns, for the species groups which we investigated, were consistent with the hypothesis. Overall, stumps and snags had the highest habitat quality (measured as average population density with equal weight given to each species) and fine woody debris the lowest, which was unexpected, since stumps were the rarest dead-wood type in unmanaged forest. We conclude that the evolutionary species pool concept did not explain patterns of species’ occurrences, and for two reasons, the concept is not reliable as a general rule of thumb: (1) what constitute habitats harbouring different species communities can only be understood from habitat-specific studies and (2) the suitability of habitats is affected by their biophysical characteristics. Thus, emulation of natural disturbances may promote biodiversity, but empirical studies are needed for each habitat to understand how natural disturbances should be emulated. We also conclude that stump extraction for bioenergy is associated with larger risks for biodiversity than fine woody debris extraction.

The Potential for Long-Term Sustainability in Seminatural Forestry: A Broad Perspective Based on Woodpecker Populations

We assessed ecological sustainability of seminatural forestry by analyzing 80-year dynamics and the current distribution of all woodpecker species in Estonia. We found that, despite the clear-cutting-based forestry system, woodpeckers inhabited commercial seminatural forests in substantial numbers, including the species generally considered vulnerable to timber harvesting. The only negative trend, a drastic decline in the Green Woodpecker, paralleled the loss of seminatural, wooded grasslands and is mostly an issue for landscape planning and agricultural land use. Major silvicultural factors supporting other species in commercial forests include natural regeneration with multiple native tree species and deadwood abundance. In such context, the main role of protected areas is to provide ecological resilience; however, we estimated that the current strict reserves could further double their carrying capacities for woodpeckers through successional recovery and, perhaps, active restoration. The long time series used were instrumental in detecting unexpected dynamics and the impacts of climatically extreme years. We conclude that (1) seminatural forestry can serve as a basis for reconciling timber harvesting and biodiversity protection at the landscape scale, given appropriate attention to key structures and landscape zoning and (2) woodpeckers represent a biological indicator system for the sustainability of forest landscapes in Europe.

A framework to optimize the restoration and retention of large mature forest tracts in managed boreal landscapes

The decreasing abundance of mature forests and their fragmentation have been identified as major threats for the preservation of biodiversity in managed landscapes. In this study, we developed a multi-level framework to coordinate forest harvestings so as to optimize the retention or restoration of large mature forest tracts in managed forests. We used mixed-integer programming for this optimization, and integrated realistic management assumptions regarding stand yield and operational harvest constraints. The model was parameterized for eastern Canadian boreal forests, where clear-cutting is the main silvicultural system, and is used to examine two hypotheses. First, we tested if mature forest tract targets had more negative impacts on wood supplies when implemented in landscapes that are very different from targeted conditions. Second, we tested the hypothesis that using more partial cuts can be useful to attenuate the negative impacts of mature forest targets on wood supplies. The results indicate that without the integration of an explicit mature forest tract target, the optimization leads to relatively high fragmentation levels. Forcing the retention or restoration of large mature forest tracts on 40% of the landscapes had negative impacts on wood supplies in all types of landscapes, but these impacts were less important in landscapes that were initially fragmented. This counter-intuitive result is explained by the presence in the models of an operational constraint that forbids diffuse patterns of harvestings, which are more costly. Once this constraint is applied, the residual impact of the mature forest tract target is low. The results also indicate that partial cuts are of very limited use to attenuate the impacts of mature forest tract targets on wood supplies in highly fragmented landscapes. Partial cuts are somewhat more useful in landscapes that are less fragmented, but they have to be well coordinated with clearcut schedules in order to contribute efficiently to conservation objectives. This modeling framework could easily be adapted and parameterized to test hypotheses or to optimize restoration schedules in landscapes where issues such as forest fragmentation and the abundance of mature or old-growth forests are a concern.

Salvage logging following fires can minimize boreal caribou habitat loss while maintaining forest quotas: An example of compensatory cumulative effects

Protected area networks are the dominant conservation approach that is used worldwide for protecting biodiversity. Conservation planning in managed forests, however, presents challenges when endangered species use old-growth forests targeted by the forest industry for timber supply. In many ecosystems, this challenge is further complicated by the occurrence of natural disturbance events that disrupt forest attributes at multiple scales. Using spatially explicit landscape simulation experiments, we gather insights into how these large scale, multifaceted processes (fire risk, timber harvesting and the amount of protected area) influenced both the persistence of the threatened boreal caribou and the level of timber supply in the boreal forest of eastern Canada. Our result showed that failure to account explicitly and a priori for fire risk in the calculation of timber supply led to an overestimation of timber harvest volume, which in turn led to rates of cumulative disturbances that threatened both the long-term persistence of boreal caribou and the sustainability of the timber supply itself. Salvage logging, however, allowed some compensatory cumulative effects. It minimised the reductions of timber supply within a range of ∼10% while reducing the negative impact of cumulative disturbances caused by fire and logging on caribou. With the global increase of the human footprint on forest ecosystems, our approach and results provide useful tools and insights for managers to resolve what often appear as lose-lose situation between the persistence of species at risk and timber harvest in other forest ecosystems. These tools contribute to bridge the gap between conservation and forest management, two disciplines that remain too often disconnected in practice.

Maximizing Conservation and Production with Intensive Forest Management: It's All About Location

Functional zoning has been suggested as a way to balance the needs of a viable forest industry with those of healthy ecosystems. Under this system, part of the forest is set aside for protected areas, counterbalanced by intensive and extensive management of the rest of the forest. Studies indicate this may provide adequate timber while minimizing road construction and favoring the development of large mature and old stands. However, it is unclear how the spatial arrangement of intensive management areas may affect the success of this zoning. Should these areas be agglomerated or dispersed throughout the forest landscape? Should managers prioritize (a) proximity to existing roads, (b) distance from protected areas, or (c) site-specific productivity? We use a spatially explicit landscape simulation model to examine the effects of different spatial scenarios on landscape structure, connectivity for native forest wildlife, stand diversity, harvest volume, and road construction: (1) random placement of intensive management areas, and (2-8) all possible combinations of rules (a)-(c). Results favor the agglomeration of intensive management areas. For most wildlife species, connectivity was the highest when intensive management was far from the protected areas. This scenario also resulted in relatively high harvest volumes. Maximizing distance of intensive management areas from protected areas may therefore be the best way to maximize the benefits of intensive management areas while minimizing their potentially negative effects on forest structure and biodiversity.

Disturbance, life history traits, and dynamics in an old-growth forest landscape of southeastern Europe

Much of our understanding of natural forest dynamics in the temperate region of Europe is based on observational studies in old-growth remnants that have emphasized small-scale gap dynamics and equilibrium stand structure and composition. Relatively little attention has been given to the role of infrequent disturbance events in forest dynamics. In this study, we analyzed dendroecological data from four stands and three windthrow patches in an old-growth landscape in the Dinaric Mountains of Bosnia and Herzegovina to examine disturbance history, tree life history traits, and compositional dynamics. Over all stands, most decades during the past 340 years experienced less than 10% canopy loss, yet each stand showed evidence of periodic intermediate-severity disturbances that removed > 40% of the canopy, some of which were synchronized over the study area landscape. Analysis of radial growth patterns indicated several life history differences among the dominant canopy trees; beech was markedly older than fir, while growth patterns of dead and dying trees suggested that fir was able to tolerate longer periods of suppressed growth in shade. Maple had the fastest radial growth and accessed the canopy primarily through rapid early growth in canopy gaps, whereas most beech and fir experienced a period of suppressed growth prior to canopy accession. Peaks in disturbance were roughly linked to increased recruitment, but mainly of shade-tolerant beech and fir; less tolerant species (i.e., maple, ash, and elm) recruited successfully on some of the windthown sites where advance regeneration of beech and fir was less abundant. The results challenge the traditional notions of stability in temperate old-growth forests of Europe and highlight the nonequilibrial nature of canopy composition due to unique histories of disturbance and tree life history differences. These findings provide valuable information for developing natural disturbance-based silvicultural systems, as well as insight into maintaining less shade-tolerant, but valuable broadleaved trees in temperate forests of Europe.