Context

Forest landscapes at the southern boreal forest transition zone are likely to undergo great alterations due to projected changes in regional climate.

Objectives

We projected changes in forest landscapes resulting from four climate scenarios (baseline, RCP 2.6, RCP 4.5 and RCP 8.5), by simulating changes in tree growth and disturbances at the southern edge of Canada’s boreal zone.

Methods

Projections were performed for four regions located on an east–west gradient using a forest landscape model (LANDIS-II) parameterized using a forest patch model (PICUS).

Results

Climate-induced changes in the competitiveness of dominant tree species due to changes in potential growth, and substantial intensification of the fire regime, appear likely to combine in driving major changes in boreal forest landscapes. Resulting cumulative impacts on forest ecosystems would be manifold but key changes would include (i) a strong decrease in the biomass of the dominant boreal species, especially mid- to late-successional conifers; (ii) increases in abundance of some temperate species able to colonize disturbed areas in a warmer climate; (iii) increases in the proportions of pioneer and fire-adapted species in these landscapes and (iv) an overall decrease in productivity and total biomass. The greatest changes would occur under the RCP 8.5 radiative forcing scenario, but some impacts can be expected even with RCP 2.6.

Conclusions

Western boreal forests, i.e., those bordering the prairies, are the most vulnerable because of a lack of species adapted to warmer climates and major increases in areas burned. Conservation and forest management planning within the southern boreal transition zone should consider both disturbance- and climate-induced changes in forest communities.

Context

Natural disturbances can have a considerable negative impact on the productivity of forest landscapes. Yet, disturbances are also important drivers of diversity, with diversity generally contributing positively to forest productivity. While the direct effects of disturbance have been investigated extensively it remains unclear how disturbance-mediated changes in diversity influence landscape productivity. Considering that disturbances are increasing in many ecosystems a better understanding of disturbance impacts is of growing importance for ecosystem management.

Objectives

Here, our objectives were to study the effect of disturbance on tree species diversity at different spatial scales (α and β diversity), and to analyze how a disturbance-mediated variation in tree species diversity affects forest productivity.

Methods

To account for long-term interactions between disturbance, diversity, and productivity and test a range of disturbance scenarios we used simulation modeling, focusing on a temperate forest landscape in Central Europe.

Results

We found an overall positive effect of disturbance on tree species diversity both with regard to α and β diversity, persisting under elevated disturbance frequencies. Productivity was enhanced by within- and between-stand diversity, with the effect of α diversity decreasing and that of β diversity increasing through the successional development. Positive diversity effects were found to be strongly contingent on the available species pool, with landscapes containing species with different life-history strategies responding most strongly to disturbance-mediated diversity.

Conclusions

We conclude that, rather than homogenizing disturbed areas, forest managers should incorporate the diversity created by disturbances into stand development to capitalize on a positive diversity effect on productivity.

Context

Global climate change impacts forest growth and methods of modeling those impacts at the landscape scale are needed to forecast future forest species composition change and abundance. Changes in forest landscapes will affect ecosystem processes and services such as succession and disturbance, wildlife habitat, and production of forest products at regional, landscape and global scales.

Objectives

LINKAGES 2.2 was revised to create LINKAGES 3.0 and used it to evaluate tree species growth potential and total biomass production under alternative climate scenarios. This information is needed to understand species potential under future climate and to parameterize forest landscape models (FLMs) used to evaluate forest succession under climate change.

Methods

We simulated total tree biomass and responses of individual tree species in each of the 74 ecological subsections across the central hardwood region of the United States under current climate and projected climate at the end of the century from two general circulation models and two representative greenhouse gas concentration pathways.

Results

Forest composition and abundance varied by ecological subsection with more dramatic changes occurring with greater changes in temperature and precipitation and on soils with lower water holding capacity. Biomass production across the region followed patterns of soil quality.

Conclusions

Linkages 3.0 predicted realistic responses to soil and climate gradients and its application was a useful approach for considering growth potential and maximum growing space under future climates. We suggest Linkages 3.0 can also can used to inform parameter estimates in FLMs such as species establishment and maximum growing space.

Context

Interactions between landscape-scale processes and fine-grained habitat heterogeneity are usually invoked to explain species occupancy in fragmented landscapes. In variegated landscapes, however, organisms face continuous variation in micro-habitat features, which makes necessary to consider ecologically meaningful estimates of habitat quality at different spatial scales.

Objectives

We evaluated the spatial scales at which forest cover and tree quality make the greatest contribution to the occupancy of the long-horned beetle Microplophorus magellanicus (Coleoptera: Cerambycidae) in a variegated forest landscape.

Methods

We used averaged data of tree quality (as derived from remote sensing estimates of the decay stage of single trees) and spatially independent pheromone-baited traps to model the occurrence probability as a function of multiple cross-scale combinations between forest cover and tree quality (with scales ranging between 50 and 400 m).

Results

Model support and performance increased monotonically with the increasing scale at which tree quality was measured. Forest cover was not significant, and did not exhibit scale-specific effects on the occurrence probability of M. magellanicus. The interactive effect between tree quality and forest cover was stronger than the independent (additive) effects of tree quality and particularly forest cover. Significant interactions included tree quality measured at spatial scales ≥200 m, but cross-scale interactions occurred only in four of the seven best-supported models.

Conclusions

M. magellanicus respond to the high-quality trees available in the landscape rather than to the amount of forest per se. Conservation of viable metapopulations of M. magellanicus should consider the quality of trees at spatial scales >200 m.

Context

Forests in the northeastern United States are currently in early- and mid-successional stages recovering from historical land use. Climate change will affect forest distribution and structure and have important implications for biodiversity, carbon dynamics, and human well-being.

Objective

We addressed how aboveground biomass (AGB) and tree species distribution changed under multiple climate change scenarios (PCM B1, CGCM A2, and GFDL A1FI) in northeastern forests.

Methods

We used the LANDIS PRO forest landscape model to simulate forest succession and tree harvest under current climate and three climate change scenarios from 2000 to 2300. We analyzed the effects of climate change on AGB and tree species distribution.

Results

AGB increased from 2000 to 2120 irrespective of climate scenario, followed by slight decline, but then increased again to 2300. AGB averaged 10 % greater in the CGCM A2 and GFDL A1FI scenarios than the PCM B1 and current climate scenarios. Climate change effects on tree species distribution were not evident from 2000 to 2100 but by 2300 some northern hardwood and conifer species decreased in occurrence and some central hardwood and southern tree species increased in occurrence.

Conclusions

Climate change had positive effects on forest biomass under the two climate scenarios with greatest warming but the patterns in AGB over time were similar among climate scenarios because succession was the primary driver of AGB dynamics. Our approach, which simulated stand dynamics and dispersal, demonstrated that a northward shift in tree species distributions may take 300 or more years.

Context

Forest landscape models (FLMs) are important tools for simulating forest changes over broad spatial and temporal scales. The ability of FLMs to accurately predict forest changes may be significantly influenced by the formulations of site-scale processes including seedling establishment, tree growth, competition, and mortality.

Objective

The objectives of this study were to investigate the effects of site-scale processes and interaction effects of site-scale processes and harvest on landscape-scale forest change predictions.

Methods

We compared the differences in species’ distribution (quantified by species’ percent area), total aboveground biomass, and species’ biomass derived from two FLMs: (1) a model that explicitly incorporates stand density and size for each species age cohort (LANDIS PRO), and (2) a model that explicitly tracks biomass for each species age cohort (LANDIS-II with biomass succession extension), which are variants from the LANDIS FLM family with different formulations of site-scale processes.

Results

For early successional species, the differences in simulated distribution and biomass were small (mostly less than 5 %). For mid- to late-successional species, the differences in simulated distribution and biomass were relatively large (10–30 %). The differences in species’ biomass predictions were generally larger than those for species’ distribution predictions. Harvest mediated the differences on landscape-scale predictions.

Conclusions

The effects of site-scale processes on landscape-scale forest change predictions are dependent on species’ ecological traits such as shade tolerance, seed dispersal, and growth rates.

Context

Forest loss and fragmentation negatively affect biodiversity. However, disturbances in forest canopy resulting from repeated deforestation and reforestation are also likely important drivers of biodiversity, but are overlooked when forest cover change is assessed using a single time interval.

Objectives

We investigated two questions at the nexus of plant diversity and forest cover change dynamics: (1) Do multitemporal forest cover change trajectories explain patterns of plant diversity better than a simple measure of overall forest change? (2) Are specific types of forest cover change trajectories associated with significantly higher or lower levels of diversity?

Methods

We sampled plant biodiversity in forests spanning the Charlotte, NC, region. We derived forest cover change trajectories occurring within nested spatial extents per sample site using a time series of aerial photos from 1938 to 2009, then classified trajectories by spatio-temporal patterns of change. While accounting for landscape and environmental covariates, we assessed the effects of the trajectory classes as compared to net forest cover change on native plant diversity.

Results

Our results indicated that forest stand diversity is best explained by forest change trajectories, while the herb layer is better explained by net forest cover change. Three distinct forest change trajectory classes were found to influence the forest stand and herb layer.

Conclusions

The influence of forest dynamics on biodiversity can be overlooked in analyses that use only net forest cover change. Our results illustrate the utility of assessing how specific trajectories of past land cover change influence biodiversity patterns in the present.

Context

Quantitative models of forest dynamics have followed a progression toward methods with increased detail, complexity, and spatial extent.

Objectives

We highlight milestones in the development of forest dynamics models and identify future research and application opportunities.

Methods

We reviewed milestones in the evolution of forest dynamics models from the 1930s to the present with emphasis on forest growth and yield models and forest landscape models We combined past trends with emerging issues to identify future needs.

Results

Historically, capacity to model forest dynamics at tree, stand, and landscape scales was constrained by available data for model calibration and validation; computing capacity; model applicability to real-world problems; and ability to integrate biological, social, and economic drivers of change. As computing and data resources improved, a new class of spatially explicit forest landscape models emerged.

Conclusions

We are at a point of great opportunity in development and application of forest dynamics models. Past limitations in computing capacity and in data suitable for model calibration or evaluation are becoming less restrictive. Forest landscape models, in particular, are ready to transition to a central role supporting forest management, planning, and policy decisions.

Recommendations

Transitioning forest landscape models to a central role in applied decision making will require greater attention to evaluating performance; building application support staffs; expanding the included drivers of change, and incorporating metrics for social and economic inputs and outputs.

Context

In heterogeneous landscapes, habitat complementation is a key process underlying the distribution of mobile species able to exploit non-substitutable resources over large home ranges. For instance, insectivorous bats need to forage in a diversity of habitat patches offering varied compositions and structures within forest landscape mosaics to fulfill their life cycle requirements.

Objectives

We aimed at analyzing the effects of forest structure and composition measured at the stand and landscape scales on bat species richness, abundance and community composition in pine plantation forests of south-western France.

Methods

We sampled bat communities at different periods of the summer season using automatic ultrasound recorders along a tree composition gradient from pine monocultures to pure oak stands. We analyzed bat species activity (as a proxy for bat abundance) and species richness with linear mixed models. Distance-based constrained ordinations were used to partition the spatio-temporal variation in bat communities.

Results

Deciduous tree cover increased bat activity and modified community composition at both stand and landscape scales. Changes in bat communities were mostly driven by landscape-scale variables while bat activity responded more to stand-scale predictors.

Conclusions

The maintenance of deciduous trees at both stand and landscape scales is likely critical for bat communities living in fast-growing conifer plantations, by increasing the availability and diversity of prey and roosting sites. Our study suggests that bats respond to forest composition at both stand and landscape scales in mosaic plantation landscapes, mainly through a resource complementation process.

Context

Many arboreal mammals in Neotropical forests are important seed dispersers that influence the spatial patterns of tree regeneration via their movement patterns, which in turn are determined by the canopy structure of the forest itself. However, the relationship between arboreal mammal movement and canopy structure is poorly understood, due in large part to the complexity of quantifying arboreal habitat structure.

Objectives

We relate detailed movement trajectories of three sympatric primate species to attributes of canopy structure derived from airborne light detection and ranging (LiDAR) in order to understand the role of structure in arboreal movement in the tropical moist forest of Barro Colorado Island, Panama.

Methods

We used high-resolution LiDAR to quantify three-dimensional attributes of the forest canopy of the entire island, high-resolution GPS tracking to map the movement patterns of the monkey species, and step selection functions to relate movement decisions to canopy attributes.

Results

We found that movement decisions were correlated with canopy height and distance to gaps, which indicate forest maturity and lateral connectivity, in all three species. In the two faster-moving species, step selection was also correlated with the thickness of the crown layer and the density of vegetation within the crown.

Conclusions

The correlations detected are fully in line with known differences in the locomotor adaptations and movement strategies of the study species, and directly reflect maximization of energetic efficiency and ability to escape from predators. Quantification of step selection in relation to structure thus provides insight into the ways in which arboreal animals use their environment.

Context

Although forest fragmentation is generally thought to impact tree growth and mortality negatively, recent work suggests some forests are resilient. Experimental forests provide an opportunity to examine the timing and extent of forest tree resilience to disturbance from fragmentation.

Objectives

We used the Wog Wog Habitat Fragmentation Experiment in southeastern Australia to test Eucalyptus growth and survivorship responses to forest fragmentation over a 26 year period.

Methods

We measured 2418 tree diameters and used spline-regression techniques to examine non-monotonic fragmentation effect over two time periods.

Results

Over the first 4 years after fragmentation, individual eucalypt tree growth was greater than in continuous forest for large trees and mortality rates were higher only within 10 m of edges. Over the following 22 years only the effects on tree growth remained and on average all fragments rebounded so that their biomass and mortality rates were equivalent to continuous forest. Importantly non-monotonic patterns were observed in growth and mortality with respect to area and distance from edge in both study periods, demonstrating that fragmentation impacts on trees can be strong in localized areas (greatest in 3 ha fragments and 0–30 m edges) and over short time periods.

Conclusions

Dry-sclerophyll eucalypt forests join the set of forest types that display resilient growth dynamics post fragmentation. Moreover, persistent non-monotonic impacts on tree growth with respect to tree size, fragment area, and fragment distance from edge, highlighting landscape fragmentation as a driver of habitat heterogeneity within remnant forest fragments.

Context

Despite decades of research, there is an intense debate about the consistency of the hump-shaped pattern describing the relationship between diversity and disturbance as predicted by the intermediate disturbance hypothesis (IDH). Previous meta-analyses have not explicitly considered interactive effects of disturbance frequency and intensity of disturbance on plant species diversity in terrestrial landscapes.

Objective

We conducted meta-analyses to test the applicability of IDH by simultaneously examining the relationship between species richness, disturbance frequency (quantified as time since last disturbance as originally proposed) and intensity of disturbance in forest landscapes.

Methods

The effects of disturbance frequency, intensity, and their interaction on species richness was evaluated using a mixed-effects model.

Results

We found that species richness peaks at intermediate frequency after both high and intermediate disturbance intensities, but the richness-frequency relationship differed between intensity classes.

Conclusions

Our study highlights the need to measure multiple disturbance components that could help reconcile conflicting empirical results on the effect of disturbance on plant species diversity.

Context

Due to the spatial heterogeneity of the disturbance regimes and community assemblages along topoclimatic gradients, the response of forest ecosystem to climate change varies at the landscape scale.

Objectives

Our objective was to quantify the possible changes in forest ecosystems and the relative effects of climate warming and fire regime changes in different topographic positions.

Methods

We used a spatially explicit model (LANDIS PRO) combined with a gap model (LINKAGES) to predict the possible response of boreal larch forests to climate and fire regime changes, and examined how this response would vary in different topographic positions.

Results

The result showed that the proportion of landscape occupied by broadleaf species increased under warming climate and frequent fires scenarios. Shifts in species composition were strongly influenced by both climate warming and more frequent fires, while changes in age structure were mainly controlled by shifts in fire regime. These responses varied in the different topographic positions, with forests in valley bottoms being most resilient to climate-fire changes and forests in uplands being more likely to shift their composition from larch-dominant to mixed forests. Such variation in the topographic response may be induced by the heterogeneities of the environmental conditions and fire regime.

Conclusions

Fire disturbance could alter the equilibrium of ecosystems and accelerate the response of forests to climate warming. These effects are largely modulated by topographic variations. Our findings suggest that it is imperative to consider topographic complexities when developing appropriate fire management policies for mitigating the effects of climate change.

Context

Habitat destruction is the leading threat to terrestrial biodiversity, isolating remnant habitat in a matrix of modified vegetation.

Objectives

Our goal was to determine how species richness in several broad taxonomic groups from remnant forest was influenced by matrix quality, which we characterized by comparing plant biomass in forest and the surrounding matrix.

Methods

We coupled data on species-area relationships (SARs) in forest remnants from 45 previously published studies with an index of matrix quality calculated using new estimates of plant biomass derived from satellite imagery.

Results

The effect size of SARs was greatest in landscapes with low matrix quality and little forest cover. SARs were generally stronger for volant than for non-volant species. For the terrestrial taxa included in our analysis, matrix quality decreased as the proportion of water, ice, or urbanization in a landscape increased.

Conclusions

We clearly demonstrate that matrix quality plays a major role in determining patterns of species richness in remnant forest. A key implication of our work is that activities that increase matrix quality, such as active and passive habitat restoration, may be important conservation measure for maintaining and restoring biodiversity in modified landscapes.

Context

The biodiversity hotspot for conservation of New Caledonia has facing high levels of forest fragmentation. Remnant forests are critical for biodiversity conservation and can help in understanding how does forest fragmentation affect tree communities.

Objective

Determine the effect of habitat configuration and availability on tree communities.

Methods

We mapped forest in a 60 km² landscape and sampled 93 tree communities in 52 forest fragments following stratified random sampling. At each sampling point, we inventoried all trees with a diameter at breast height ≥10 cm within a radius of 10 m. We then analysed the response of the composition, the structure and the richness of tree communities to the fragment size and isolation, distance from the edge, as well as the topographical position.

Results

Our results showed that the distance from the forest edge was the variable that explained the greatest observed variance in tree assemblages. We observed a decrease in the abundance and richness of animal-dispersed trees as well as a decrease in the abundance of large trees with increasing proximity to forest edges. Near forest edges we found a shift in species composition with a dominance of stress-tolerant pioneer species.

Conclusions

Edge-effects are likely to be the main processes that affect remnant forest tree communities after about a century of forest fragmentation. It results in retrogressive successions at the edges leading to a dominance of stress-tolerant species. The vegetation surrounding fragments should be protected to promote the long process of forest extension and subsequently reduce edge-effects.

Context

Urbanization has altered many landscapes around the world and created novel contexts and interactions, such as the rural–urban interface.

Objectives

We sought to address how a forest patch’s location in the rural–urban interface influences which avian species choose to occur within the patch. We predicted a negative relationship between forest bird richness and urbanization surrounding the patch, but that it would be ameliorated by the area of tree cover in the patch and matrix, and that total tree-cover area would be more influential on forest bird species richness than area of tree cover in the focal patch alone.

Methods

We conducted bird surveys in 44 forest patches over 2 years in Southeast Michigan and evaluated bird presence and richness relative to patch and matrix tree cover and development density.

Results

We observed 43 species, comprised of 21 Neotropical migrants, 19 residents, and three short-distance migrants. Focal-patch tree-cover area and the matrix tree-cover area were the predominant contributors to a site’s overall forest-bird species richness at the rural–urban interface, but the addition of percent of over-story vegetation and percentage of deciduous tree cover influenced the ability of the patches to support forest species, especially Neotropical migrants. Development intensity in the matrix was unrelated to species richness and only had an effect in four species models.

Conclusions

Although small forest patches remain an important conservation strategy in developed environments, the influence of matrix tree cover suggests that landscape design decisions in surrounding matrix can contribute conservation value at the rural–urban interface.

Context

Complex structural connectivity patterns can influence the distribution of animals in coastal landscapes, particularly those with relatively large home ranges, such as birds. To understand the nuanced nature of coastal forest avifauna, where there may be considerable overlap in assemblages of adjacent forest types, the concerted influence of regional landscape context and vegetative structural connectivity at multiple spatial scales warrants investigation.

Objectives

This study determined whether species compositions of coastal forest bird assemblages differ with regional landscape context or with forest type, and if this is influenced by structural connectivity patterns measured at multiple spatial scales.

Methods

Three replicate bird surveys were conducted in four coastal forest types at ten survey locations across two regional landscape contexts in northeast Australia. Structural connectivity patterns of 11 vegetation types were quantified at 3, 6, and 12 km spatial scales surrounding each survey location, and differences in bird species composition were evaluated using multivariate ordination analysis.

Results

Bird assemblages differed between regional landscape contexts and most coastal forest types, although Melaleuca woodland bird assemblages were similar to those of eucalypt woodlands and rainforests. Structural connectivity was primarily correlated with differences in bird species composition between regional landscape contexts, and correlation depended on vegetation type and spatial scale.

Conclusions

Spatial scale, landscape context, and structural connectivity have a combined influence on bird species composition. This suggests that effective management of coastal landscapes requires a holistic strategy that considers the size, shape, and configuration of all vegetative components at multiple spatial scales.

Context

Increasing demands on land for agriculture have resulted in large-scale clearance and fragmentation of forests globally. In fragmented landscapes, species that tolerate or exploit the matrix will persist, while those that do not, frequently decline. Knowledge of matrix use is therefore critical to predicting extinction proneness of species in modified landscapes and defining the value of land for conservation management.

Objectives

In a fragmented landscape consisting of seven remnant patches surrounded by agricultural land and a large Eucalyptus forest, we explored (i) population connectivity of common ringtail possums, Pseudocheirus peregrinus, to determine the permeability of the agricultural matrix, and (ii) genetic consequences of forest fragmentation.

Methods

238 common ringtail possums were screened at 14 microsatellite markers and analysed using a range of genetic techniques.

Results

We observed significant genetic differentiation among all patches and limited dispersal through the agricultural matrix, even between neighbouring patches. Consequences of this were a six- to ten-fold increase in genetic dissimilarity over an equivalent geographic distance across patches compared with sites in the continuous forest and a significant reduction in genetic diversity, particularly in patches that were geographically more isolated from their neighbours.

Conclusions

We conclude that the agricultural matrix has a number of characteristics that make it unsuitable for facilitating movement of possums through this landscape, and recommend several management strategies to mitigate the impacts of fragmentation on this and other arboreal species for their conservation.

Context

Forecasting the expansion of forest into Alaska tundra is critical to predicting regional ecosystem services, including climate feedbacks such as carbon storage. Controls over seedling establishment govern forest development and migration potential. Ectomycorrhizal fungi (EMF), obligate symbionts of all Alaskan tree species, are particularly important to seedling establishment, yet their significance to landscape vegetation change is largely unknown.

Objective

We used ALFRESCO, a landscape model of wildfire and vegetation dynamics, to explore whether EMF inoculum potential influences patterns of tundra afforestation and associated flammability.

Methods

Using two downscaled CMIP3 general circulation models (ECHAM5 and CCCMA) and a mid-range emissions scenario (A1B) at a 1 km² resolution, we compared simulated tundra afforestation rates and flammability from four parameterizations of EMF effects on seedling establishment and growth from 2000 to 2100.

Results

Modeling predicted an 8.8–18.2 % increase in forest cover from 2000 to 2100. Simulations that explicitly represented landscape variability in EMF inoculum potential showed a reduced percent change afforestation of up to a 2.8 % due to low inoculum potential limiting seedling growth. This reduction limited fuel availability and thus, cumulative area burned. Regardless of inclusion of EMF effects in simulations, landscape flammability was lower for simulations driven by the wetter and cooler CCCMA model than the warmer and drier ECHAM5 model, while tundra afforestation was greater.

Conclusions

Results suggest abiotic factors are the primary driver of tree migration. Simulations including EMF effects, a biotic factor, yielded more conservative estimates of land cover change across Alaska that better-matched empirical estimates from the previous century.