Temperate Forest Landscape Research Articles

Beyond resilience: Responses to changing climate and disturbance regimes in temperate forest landscapes across the Northern Hemisphere.

Climate change has profound impacts on forest ecosystem dynamics and could lead to the emergence of novel ecosystems via changes in species composition, forest structure, and potentially a complete loss of tree cover. Disturbances fundamentally shape those dynamics: the prevailing disturbance regime of a region determines the inherent variability of a system, and its climate-mediated change could accelerate forest transformation. We used the individual-based forest landscape and disturbance model iLand to investigate the resilience of three protected temperate forest landscapes on three continents-selected to represent a gradient from low to high disturbance activity-to changing climate and disturbance regimes. In scenarios of sustained strong global warming, natural disturbances increased across all landscapes regardless of projected changes in precipitation (up to a sevenfold increase in disturbance rate over the 180-year simulation period). Forests in landscapes with historically high disturbance activity had a higher chance of remaining resilient in the future, retaining their structure and composition within the range of variability inherent to the system. However, the risk of regime shift and forest loss was also highest in these systems, suggesting forests may be vulnerable to abrupt change beyond a threshold of increasing disturbance activity. Resilience generally decreased with increasing severity of climate change. Novelty in tree species composition was more common than novelty in forest structure, especially under dry climate scenarios. Forests close to the upper tree line experienced high novelty in structure across all three study systems. Our results highlight common patterns and processes of forest change, while also underlining the diverse and context-specific responses of temperate forest landscapes to climate change. Understanding past and future disturbance regimes can anticipate the magnitude and direction of forest change. Yet, even across a broad gradient of disturbance activity, we conclude that climate change mitigation is the most effective means of maintaining forest resilience.

Gap expansion is the dominant driver of canopy openings in a temperate mountain forest landscape

Abstract Natural disturbances are important drivers of forest dynamics, and canopy gaps are their fingerprints in forest ecosystems. Gaps form and persist because of the interplay of tree mortality and regeneration. They can have long‐lasting impacts on ecosystems, yet the temporal dynamics of gap formation and closure remains poorly quantified. We analysed 11,331 canopy gaps and their changes through time across 3999 ha of unmanaged temperate mountain forests at Berchtesgaden National Park (Germany). We assessed gap formation and closure using three repeat lidar acquisitions between 2009 and 2021, analysing canopy height changes at 1 m horizontal resolution. Our objective was to determine the dominant mode of gap formation, distinguishing the creation of new gaps from the expansion of existing ones. Additionally, we studied the rate of gap closure, considering closure from tree regeneration and lateral crown expansion. Gap formation was primarily driven by gap expansion rather than the initiation of new gaps. Gap expansion accounted for 81.3% of gap formation, although new gaps were on average twice as large as gap expansions. Only 1.4% of gaps did not expand over the 12‐year study period, and Norway spruce forests had the highest rate of gap expansion. Overall, gap closure rate (0.74 ha 100 ha−1 year−1) was higher than gap formation (0.58 ha 100 ha−1 year−1) in our study system. Ingrowth of the regenerating tree cohort was the primary mode of gap closure, with lateral crown expansion accounting for 20% of all gap area closed. Mixed‐species stands had the highest rate of gap closure, and gaps <0.1 ha closed faster than larger gaps. Synthesis. While canopy openings are generally small in the European Alps, we show that they keep growing over multiple years, underlining that gap expansion is an important driver of temperate forest dynamics. Canopy gaps closed faster than they were created, highlighting the resilience of European mountain forests to natural disturbances. However, as disturbances are projected to increase under climate change, this resilience might be challenged in the future, requiring a continuous monitoring of gap dynamics as an important early warning indicator of forest change.

Private land management is more important than public land in sustaining oaks in temperate forests in the eastern U.S.

Preserving the abundance and stocking of oaks (Quercus spp.) has become increasingly challenging in temperate hardwood forests of the eastern US in recent decades due to a remarkable shift in dominance to mesophytic species (e.g., red maple Acer rubrum). Studies have shown that efforts to sustain oaks while restraining maples yield limited success. Given that a significant portion of forestlands in the eastern U.S. are privately owned, it is critical to assess whether current forest management on cross-ownership forests can achieve those objectives. However, such assessments are rare. In this study, we employed a landscape modeling approach to investigate the long-term outcomes (i.e., 150-year forest composition and structure) of business-as-usual management and alternative management in a large, temperate hardwood forest landscape in Ohio, US. The business-as-usual management continues the current existing management practices, whereas the alternative management increases the pace and scale of forest management on both private and public lands to favor oaks. We compared the basal area and relative dominance for oaks (including Q. alba, Q. coccinea, Q. prinus, Q. rubra, and Q. velutina) and maples (including A. rubrum, A. saccharinum, and A. saccharum). Our results demonstrate that the implementation of business-as-usual management practices on both private and public lands may not effectively ensure the long-term sustainability of oak populations, but instead promote the proliferation of maple species over time. By contrast, alternative management on both private and public lands can effectively sustain oaks across a range of diameter classes while mitigating the growth of large, dominant maples. Our study emphasizes the influential role of private lands in driving oak-maple dynamics at the regional scale, as they can generate significant regional effects even when public lands continue with their business-as-usual management practices. Starting conditions based on landownership are crucial considerations for understanding these dynamics over time.

No generality in biodiversity-productivity relationships along elevation in temperate and subtropical forest landscapes

An improved understanding of biodiversity-productivity relationships (BPRs) along environmental gradients is crucial for effective ecosystem management and biodiversity conservation. The stress-gradient hypothesis suggests that BPRs are stronger in stressful environments compared to more favorable conditions. However, there is limited knowledge regarding the variation of BPRs along elevational gradients and their generality across different landscapes. To study how BPRs change with elevation, we harnessed inventory data on 6,431 trees from 152 plots surveyed twice in eight to ten year intervals in mountain forests of temperate Europe and subtropical Asia. We quantified the relationship between aboveground productivity and different biodiversity measures, including taxonomic, functional, and phylogenetic diversity. To elucidate the processes underlying BPRs, we studied the variation of different functional traits along elevation across landscapes. We found no general pattern of BPRs across landscapes and elevations. Relationships were neutral for all biodiversity measures in temperate forests, and negative for taxonomic and functional diversity in subtropical forests. BPRs were largely congruent between taxonomic, functional and phylogenetic diversity. We found only weak support for the stress-gradient hypothesis, with BPRs turning from negative to positive (effect not significant) close to the tree line in subtropical forests. In temperate forests, however, elevation patterns were strongly modulated by species identity effects as influenced by specific traits. The effect of traits such as community-weighted mean of maximum plant height and wood density on productivity was congruent across landscapes. Our study highlights the context-dependence of BPRs across elevation gradients and landscapes. Species traits are key modulating factors of BPRs and should be considered more explicitly in studies of the functional role of biodiversity. Furthermore, our findings highlight that potential trade-offs between conserving biodiversity and fostering ecosystem productivity exist, which require more attention in policy and management.

Forest recovery through applied nucleation: Effects of tree islet size and disperser mobility on tree recruitment in a temperate landscape

The plantation of tree islets within deforested areas (applied nucleation) has been proposed as a restoration strategy able to catalyze tree colonization in the matrix with reasonable costs and labor compared to traditional restoration methods such as extensive plantations. However, recent work has questioned its effectiveness in comparison to natural forest regeneration, and observational studies have eventually reported a limited expansion of tree islets after years of planting. To infer the processes affecting the effectiveness of applied nucleation, we used a stochastic model able to predict avian movement and fruit consumption, tree seed dispersal and seedling establishment in a fragmented temperate forest landscape of northern Spain. First, we simulated scenarios of natural regeneration and compared them to applied nucleation in terms of tree colonization in the remaining deforested matrix. Subsequently, in applied nucleation scenarios we assessed the effects of islet size and matrix area recovered on tree recruitment into the matrix. Also, we evaluated if such effects were mediated by the scale of movement of frugivores. Our results showed that applied nucleation triggers matrix colonization by trees at higher rates than natural regeneration because it avoids frugivore entrapment within forest edges. Also, that large tree islets can hamper matrix colonization despite being visited more frequently. If large tree islets offer abundant resources, animals do not need to leave their boundaries, concentrating seed deposition within islets. As expected, such effects depended on the scale of movement of frugivores. Our work highlights that in nucleated landscapes, islets harboring fruit-producing trees should attract animal dispersers, and also foster animal inter-islet movement. Both conditions should be met to ensure seed deposition and seedling establishment in the deforested matrix, promoting forest recovery independent of islet expansion through vegetative growth. To achieve these restoration goals, we propose establishing islets whose size and inter-islet distances matches the scale of movement of main seed dispersers present in the area.

Regional sets of diverse, specialized ground beetle and plant assemblages recolonise China’s restored temperate forest landscapes

Following the historic destruction of China’s forests, large protected forest landscapes have been reestablishment across the country in recent decades. Currently, the species assemblages inhabiting these landscapes remain widely unknown. Here, we aim to establish whether the new temperate forest landscapes in Eastern China, composed of plantation, secondary and remnant mature forest patches, are dominated by widely distributed habitat generalists, widely distributed habitat specialists, or by sets of highly localized forest habitat specialist species, using vascular plants and ground beetles as case studies. We sampled plants and ground beetles on 159 plots representing different forest types distributed across ten study regions. The Chord-normalized expected species shared (CNESS) dissimilarity for beetles and Jaccard dissimilarity for plants were calculated to establish species’ turnover patterns, while we used structural equation and multiple regression models for dissimilarity matrices to establish the relative importance of location, elevation and biotic interactions in explaining large-scale distribution patterns of species assemblages. Both taxa showed highly regionalized recruitment, with plant communities responding strongly to latitude, and to geographic location in general, while the composition of ground beetle communities appeared strongly governed by both the composition of the vegetation and study plot location. Both assemblages showed a distinct lack of widespread habitat generalists. Our results demonstrate for the first time that local assemblages of forest specialist species appear to have survived last century’s deforestation in unknown refugia before successfully re-colonizing China’s restored forest ecosystems. We argue that restored forest landscapes can play a significant role in the conservation of temperate China’s biodiversity at both local and regional scales.

Brief communication: Comparison of in situ ephemeral snow depth measurements over a mixed-use temperate forest landscape

Abstract. The accuracy and precision of snow depth measurements depend on the measuring device and the conditions of the site and snowpack in which it is being used. This study compares collocated snow depth measurements from a magnaprobe snow depth probe and a Federal snow tube in an ephemeral snow environment. We conducted three snow depth sampling campaigns from December 2020 to February 2021 that included 39 open-field and coniferous-, mixed-, and deciduous-forest sampling sites in Durham, New Hampshire, United States. For all sampling campaigns and land cover types, with a total of 936 paired observations, the magnaprobe snow depth measurements were consistently deeper than those of the snow tube. There was a 12 % average difference between the magnaprobe (14.9 cm) and snow tube (13.2 cm) average snow depths with a greater difference in the forest (1.9 cm) than the field (1.3 cm). This study suggests that snow depth measurements using a Federal snow tube can avoid overprobing with an ephemeral snowpack in forested environments.

Current management in national and state forests has important but limited impacts on sustaining oaks in temperate forests of the eastern U.S

Active management for promoting oaks (Quercus spp.) and restraining maples (Acer spp.) is mostly conducted in public forests (e.g., national forests [NF] and state forests [SF]) because of oaks' ecological and economic importance. Studies have shown that current management efforts have limited success, meanwhile, oak-dominant forests continue to shift in composition and structure to shade-tolerant, fire-sensitive mesophytic species (e.g., red maple A. rubrum). It remains to be evaluated whether current management can achieve its objectives in public forests and at regional scales. In this study, we investigated the long-term outcomes of business-as-usual (BAU) and alternative management (AltMgt) scenarios in a large, temperate hardwood forest landscape in southern Ohio, US. The BAU approach simulates contemporary management, informed by harvest records across public lands and a geospatial disturbance database (i.e., LANDFIRE) to infer private land management. Whereas the AltMgt scenario increases the pace and scale of forest management on public lands through two-stage oak shelterwood harvests, treated every ten years across 10% of the land area with private land remaining as BAU. We used a spatially explicit and dynamic forest landscape model to project species compositional and structural changes under these two scenarios. Our results demonstrate that BAU management in public forests may not successfully sustain oak but instead favors the colonization of maples. Further, management objectives to promote oaks could be achieved on public forests under the AltMgt scenario, but such alternative management had limited impacts at the regional scale when including private lands. The management of NF and SF has a crucial role in driving regional changes in oak and maple abundance, particularly when private lands continued their BAU management. Starting conditions by landownership are also important considerations for oak-maple dynamics through time, implying the need to have a range of priorities and objectives, under different time frames, when developing long-term conservation plans for oak forests at regional-scales.

Physiological and Psychological Relaxing Effects of Viewing a Warm Temperate Forest and Urban Landscape for University Students

Physiological and Psychological Relaxing Effects of Viewing a Warm Temperate Forest and Urban Landscape for University Students

Improved modeling of canopy transpiration for temperate forests by incorporating a LAI-based dynamic parametrization scheme of stomatal slope

The ecosystem-level conductance-photosynthesis models, which represent a linearly coupled relationship between canopy stomatal conductance (Gs) and CO2 assimilation, have been increasingly used for modeling transpiration (Tc). As a key parameter in these models, the slope parameter (G1) has been observed to vary considerably over the seasons in the field, but is often parametrized with a biome-specific temporally constant G1, resulting in large potential uncertainty. Here we hypothesized that G1 varies with leaf area index (LAI) phenology and soil water content (SWC) seasonality, and accurate characterization of G1 seasonality offers an avenue to improve Tc modelling. To test these hypotheses, we first investigated the seasonality of Eddy flux-derived G1 and then explored its relationship with satellite-derived LAI and field-observed SWC seasonality at 12 temperate forest FLUXNET sites across the Northern Hemisphere. Last, we cross-compared the two schemes of model parameterization of G1 for modeling Tc: (1) a constant G1 (FIX) and (2) a dynamic G1 parameterized using the selected variables (DYN). Our results show G1 displays considerable seasonal variations across all sites, with a minimum value in mid-summer. Further variance partitioning analysis demonstrates that the seasonal variations in G1 show direct linkages with LAI phenology rather than SWC seasonality likely associated with leaf aging and ontogeny development. Last, we found relative to the FIX model, the DYN model (using LAI for G1 parameterization) significantly reduced the model uncertainty in terms of RMSE by 24.6 ± 11.8% and 32.0 ± 8.7%, respectively for Gs and Tc at a daily scale. These results collectively improve our understanding of the dynamic pattern and proximate controls of G1 seasonality, and highlight the effectiveness of using remote sensing-derived LAI phenology for improved characterization of G1 seasonality that ultimately contributes to the improved process model simulations of the seasonal dynamics of Gs and Tc across temperate forest landscapes.

Forage offering and seasonal intake comparisons to evaluate European rabbit threat in Nothofagus forests of southern Patagonia

BackgroundThe European rabbit (Oryctolagus cuniculus L. 1758) was introduced into different regions of the world, generating significant trade-offs that critically impacted native vegetation. Here, we evaluate the rabbit's forage intakes in three vegetation types (forests, shrublands, and grasslands) along the four seasons in a temperate forest landscape in Southern Patagonia and discuss the potential threats over native vegetation. We formulated the following questions: (i) what is the forage offer at each vegetation type? (ii) what is the rabbit's forage intake and how it varied across the seasons along the year? and (iii) which vegetation types and plant life forms were more used according to the rabbit's forage intakes?MethodsWe censused understory vegetation to characterize the forage offer at each vegetation type and determined seasonal dietary intakes using microhistological analysis of pellets. The plant species identified in the field were grouped according to life form classes (tree regeneration, shrubs, forbs, graminoids, orchids, ferns, bryophytes, and hemiparasites). Data were analysed through uni- and multi-variate analyses, determining relationships between forage offer and the rabbit's forage intakes.ResultsForage intakes revealed changes in plant life form consumption across vegetation types, where intake pressure was considerably different for tree regeneration (p = 0.001), graminoids (p = 0.001), and hemiparasites (p = 0.001). Besides, significant changes in consumption among seasons were detected for shrubs (p = 0.001), ferns (p = 0.030), and hemiparasites (p = 0.002). Although many species play an important role in the rabbit's forage intake networks (e.g., Chiliotrichum diffusum, Holcus lanatus), the strongest intake linkages were found in exotic grasses (e.g., Poa pratensis and Festuca sp.), native hemiparasites (e.g., Misodendrum sp.), native shrubs (e.g., Empetrum rubrum), and native trees (e.g., Nothofagus sp.). The summer and autumn seasons presented higher intake compared to the winter and spring seasons. Furthermore, hemiparasites intake (e.g., Misodendrum sp.) suggests that rabbits utilize different forage sources depending on the vegetation types.ConclusionsRabbits regularly inhabit the forest, even though it is not their preferred vegetation type to live. Rabbit management entails isolating regions that are more favourable to intake and emphasizing the year's season for rabbit control efforts.

Disturbance has variable effects on the structural complexity of a temperate forest landscape

The temporal dynamics of forest canopy structure are influenced by disturbances that alter vegetation quantity and distribution. While canopy structural indicators such as leaf area index (LAI), canopy cover, and canopy height have been widely studied in the context of disturbance, the post-disturbance temporal dynamics of structural complexity, which summarizes the heterogeneity of vegetation arrangement, are poorly understood. With the goal of advancing conceptual and empirical understanding of the temporal dynamics of structural complexity following disturbance, we synthesized results from three large-scale disturbance manipulation experiments at the University of Michigan Biological Station (UMBS): the 4-year Forest Resilience Threshold Experiment (FoRTE) manipulating levels of disturbance severity; the decade-long Forest Accelerated Succession Experiment (FASET), in which all early successional tree species were stem-girdled within 39 ha in the same landscape; and forest chronosequences established following clear-cut harvesting. We found that the temporal dynamics of canopy structure following disturbance were dependent upon three factors: (1) the source and severity of disturbance; (2) the spatial and temporal scales of analysis; and (3) the measure of structure assessed. Unlike vegetation area index and canopy cover, which initially decreased in response to disturbance, structural complexity measures such as canopy and top rugosity did not consistently respond to moderate levels of disturbance severity. Over multi-decadal timescales, structural complexity increased to a maximum, regardless of whether fire occurred at the time of stand establishment, but intervening low-to-moderate severity disturbance in regrown century-old forests altered trajectories of canopy rugosity. We conclude that structural complexity indicators display a more nuanced temporal and directional response to disturbance than conventional leaf area and cover indexes. Predicting what disturbance conditions modify trajectories of structural complexity remains critical to disturbance characterization and the inference of ecosystem functioning.

A Hierarchical Binary Process Model to Assess Deviation from Desired Ecological Condition across a Broad Forested Landscape in Alabama

This work describes the development and analysis of a spatially explicit environmental model to estimate the current, ecological, condition class of a managed forest landscape in the southern United States. The model could be extendable to other similar temperate forest landscapes, yet is characterized as a problem-specific, hierarchical, binary process model given the explicit relationships it recognizes between the management of southern United States pine-dominated natural forests and historical ecological conditions. The model is theoretical, based on informed proposals of the landscape processes that influence the ecological condition, and their relationship to perceived ecological condition. The modeling effort is based on spatial data that describe the historical forest community classes, forest plan provisions, fire history, silvicultural treatments, and current vegetation conditions, and six potential ecological condition classes (ECC) are assigned to lands. A case study was provided involving a large national forest, and validation of the outcomes of the modelling effort suggested that the overall accuracy when predicting the exact ecological condition class was about 46%, while the overall accuracy ±1 class was about 81%. For large, heterogeneous forest areas, issues remain in estimating the input variables relatively accurately, particularly the pine basal area.

Spring phenological variability promoted by topography and vegetation assembly processes in a temperate forest landscape

Plant phenological processes significantly impact ecosystem function and services across multiple ecological scales and are widely viewed to be among the most sensitive indicators of global environmental change. Remote sensing has crucially expanded our understanding of phenological variability. Yet, we continue to lack a complete mechanistic understanding of phenology and its variability and drivers, which is important to the development of predictive models, especially under continued environmental change. We combined field inventories and Land Surface Phenology (LSP) approaches, using 36 years of Landsat phenological observations, to characterize the degree to which long-term spring greenup patterns are shaped by topography, vegetation, and topographically structured vegetation assembly processes within a dissected forest landscape in southeastern Ohio. We found temporal and spatial variability among the field samples where greenup patterns displayed rapid change (18 total days) over relatively short distances (<1 km). Slope position explained the most variation (35%), where the bases of hills displayed the latest timing in spring greenup. However, we found that differences in terrain aspect and slope influenced canopy diversity, height, and composition of forest stands, influencing plant community processes that support heterogeneity in spring leaf-out timing. Understanding how forest phenology is shaped by direct and often complex interacting processes that influence the distribution of species assemblages supports new insight into phenological variability and, importantly, the management of forest ecosystems facing continued environmental change.

Effects of stand edges on the structure, functioning, and diversity of a temperate mountain forest landscape

AbstractHuman land use is fragmenting forests around the globe, increasing the edge density in forest landscapes. More frequent natural disturbances also increase the presence of edges in forest ecosystems. Studying a mountain landscape in the Eastern Alps, we contrasted 661 plots situated at varying distances from a stand edge with 615 plots sampled in forest interiors. Our objectives were (1) to analyze the strength of edge effects on forest structure, functioning, and diversity; (2) to determine the penetration depth of edge effects into the forest interior; and (3) to quantify the difference between permanent edges (i.e., to a different land cover type) and transient edges (as created e.g., by natural disturbances). Edges affected forest biomass accumulation negatively (basal area, litter depth, live tree carbon), but had positive effects on diversity (variation in tree diameter, effective plant species number, plant species richness, number of red‐listed plant species). Biodiversity indicators responded most strongly to the presence of edges. The maximum distance of a significant edge effect was &lt;50 m across all indicators. Effects on forest structure and functioning were generally stronger at transient edges compared to permanent edges. Our findings highlight that both permanent and transient edges have a considerable influence on forest ecosystems and should be considered more explicitly in the analysis and management of forest landscapes.

Moderate- to High-Severity Disturbances Shaped the Structure of Primary Picea Abies (L.) Karst. Forest in the Southern Carpathians

Research Highlights: Past disturbances occurred naturally in primary forests in the Southern Carpathians. High- and moderate-severity disturbances shaped the present structure of these ecosystems, which regenerated successfully without forestry interventions. Background and Objectives: Windstorms and bark beetle outbreaks have recently affected large forest areas across the globe, causing concerns that these disturbances lie outside the range of natural variability of forest ecosystems. This often led to salvage logging inside protected areas, one of the main reasons for primary forest loss in Eastern Europe. Although more than two-thirds of temperate primary forests in Europe are located in the Carpathian region of Eastern Europe, knowledge about how natural disturbances shape the forest dynamics in this region is highly essential for future management decisions. Material and Methods: We established our study in a primary forest valley situated in the centre of the largest temperate primary forest landscape in Europe (Făgăraș Mountains). A dendrochronological investigation was carried out to reconstruct the natural disturbance history and relate it to the present forest structure. Results: The dendrochronological analysis revealed high temporal variability in the disturbance patterns both at the patch and stand level. Moderate severity disturbance events were most common (20–40% of canopy disturbed in 60% of the plots) but high severity events did also occur (33% of the plots). Regeneration was spruce-dominated and 71% of the seedlings were found on deadwood microsites. Conclusions: We conclude that the current structure of the studied area is a consequence of the past moderate-severity disturbances and sporadic high-severity events. The peak in disturbances (1880–1910) followed by reduced disturbance rates may contribute to a recent and future increase in disturbances in the Făgăraș Mts. Our findings show that these disturbance types are within the range of natural variability of mountain spruce forests in the Southern Carpathians and should not be a reason for salvage logging in primary forests from this area.

A simple-to-use management approach to boost adaptive capacity of forests to global uncertainty

Given the uncertainty of global environmental changes, forest managers need reliable and science-based tools to support planning decisions. To evaluate the state of forests as well as the outcomes of new management practices aimed at fostering the adaptive capacity of forest ecosystems, methods and metrics for practitioners should be self-explanatory, based on easily-available data, and straightforward to use. Here, we present and apply the functional network approach, a trait-based approach that scales-up from species functional traits to community-level functional diversity and from stands to landscape-level functional connectivity, to guide sustainable forest management when faced with global change. In the functional network approach, (1) tree and shrub species are clustered into functional groups based on selected functional traits, (2) forest stands become the nodes of the network, and (3) functional traits can be exchanged between nodes according to species dispersal capacity via functional connectivity. We complemented the functional network approach with an assessment of stand-level vulnerability to natural disturbances. This new approach was applied to a mixed temperate forest landscape in south-eastern Canada to test four management scenarios varying in intensity (5–40% of the landscape area) and silvicultural strategy, including planting tree species from rare functional groups or harvesting tree species from predominant functional groups. Managed stands were ranked according to functional diversity and vulnerability to disturbances, and species were considered for planting based on their contribution to functional diversity and level of vulnerability. We found that a species-rich forest may be a functionally poor ecosystem so its adaptive capacity and resilience may be strongly compromised in the face of high global uncertainty. In addition, both functional diversity and connectivity increased with more intense management, and when functionally rare species were planted. By adopting the functional network approach, forest practitioners have a new simple-to-use tool to evaluate landscape-level functional diversity, vulnerability, and functional connectivity. This tool can be used to inform both plans for mitigating natural disturbances and strategies for enhancing overall ecosystem adaptive capacity to future environmental conditions and societal demands.

Reconciling forest profitability and biodiversity conservation under disturbance risk: the role of forest management and salvage logging

Forest management and disturbances are among the main drivers of changes in forest dynamics in temperate ecosystems. To promote and maintain forest multifunctionality and species persistence in the landscape, it is critical that the interactions between these factors and forest biodiversity are disentangled. Still, the relationships between disturbances and forest management are poorly understood and may hinder an adequate planning of management and conservation actions in these forests. Here we address this issue via a coupled ecological-economic modeling system under different climate change scenarios. We employed data from a large-scale field-based research in southwestern Germany, in combination with a climate-sensitive forest growth model. Thereby, we quantified changes in multiple biodiversity indicators (including richness of birds, bats and flying insect orders) and tree microhabitats (TreMs) in the face of disturbance and management interventions. Our results show that windstorms may cause economic damage in managed forests, but at the same time improve biodiversity indicators in these areas. Salvage logging, however, may dampen these positive impacts for the majority of indicators considered. Moreover, management solutions targeting at wind risk mitigation may be detrimental to some taxa (e.g. forest birds) but still performed better than the business-as-usual management, in terms of the biodiversity indicators applied. We conclude that considering disturbance impacts on forest dynamics will be key to maintain the sustainability in the use of forest resources and support species persistence in temperate forest landscapes.

The response of canopy height diversity to natural disturbances in two temperate forest landscapes

ContextStructural diversity strongly influences habitat quality and the functioning of forest ecosystems. An important driver of the variation in forest structures are disturbances. As disturbances are increasing in many forest ecosystems around the globe, it is important to understand how structural diversity responds to (changing) disturbances.ObjectivesOur aim was to quantify the relationship between forest disturbances and structural diversity with a focus on diversity in canopy height.MethodsWe assessed diversity in canopy height for two strictly protected Central European forest landscapes using lidar data. We used a multi-scale framework to quantify within-patch (α), between-patch (β), and overall (γ) diversity. We then analysed the variation in canopy height diversity over an extensive gradient of disturbance rates.ResultsDiversity in canopy height was strongly driven by disturbance rate, with highest overall diversity between 0.5 and 1.5% of the forest area disturbed per year. The unimodal responses of overall diversity to disturbance emerged from contrasting within- and between-patch responses, i.e., a decrease in within-patch diversity and an increase in between-patch diversity with increasing disturbance. This relationship was consistent across study landscapes, spatial scales, and diversity indicators.ConclusionThe recent wave of natural disturbances in Central Europe has likely fostered the structural diversity of forest landscapes. However, a further increase in disturbance could result in the crossing of a tipping point (at ~ 1.5% of forest area disturbed per year), leading to substantial structural homogenization.

Conserving woodland butterflies in managed forests: Both local and landscape factors matter

The conservation of forest biodiversity is increasingly relying on forest landscapes managed for timber production. A precondition for successful biodiversity conservation in intensively managed landscapes is a good understanding of habitat- and landscape-level drivers of species diversity. In this study, we investigated the effects of habitat characteristics and landscape context on the species richness and composition of butterflies in temperate forest landscapes routinely managed by clear-cutting. Our focus was on forest-dependent species. Even though about a quarter of the entire butterfly fauna in Europe are associated with forest habitats, the drivers of their diversity are poorly known. We used data from an unprecedentedly extensive butterfly survey, conducted in more than 400 sites distributed across all major forest types in Estonia (Northern Europe). Our data indicate that, generally, forests harvested for timber production remain suitable as habitats for forest butterflies: across the study sites, we recorded almost the full complement of their total regional species richness. By far the most influential driver of local butterfly species richness in such forests appears to be the proportion of forest cover in the surrounding landscape. The species richness of forest butterflies starts to show signs of decline at remarkably high levels of forest cover in the landscape. Surprisingly, landscape-scale forest heterogeneity around study sites had no discernible effect on local species richness, the pattern plausibly resulting from low mobility of forest butterflies. The most important habitat-scale predictor of butterfly species richness was soil moisture, with butterfly communities being most species-rich in forests on soils of intermediate moisture. Different forest types contribute to the regional species pool of forest butterflies in a complementary manner. No single forest type alone provides habitat for the entire species pool: peaks of abundance of different species are distributed across multiple forest types. Accordingly, a substantial part of the variation in species assemblages could be attributed to characteristic soil conditions (moisture and pH) of different forest types. Our findings imply that both the extent and heterogeneity of forest landscapes are important for maintaining the diversity of forest butterflies at the landscape scale.