Landscape context affects the success of habitat restoration: large‐scale colonization patterns of saproxylic and fire‐associated species in boreal forests

Aim Restoration of habitats may be used as a conservation tool when ecosystems have lost their natural structure, dynamics or functioning over large areas. Controlled and planned use of fire could be an effective way to restore habitats of many threatened species in boreal forests where fire suppression has been effective. We asked whether the large‐scale landscape context affects the occurrence of rare and threatened species in forest habitats that have been burned to restore their fire‐related structures. Location Boreal forests in southern Finland. Methods We designed a large‐scale field experiment that included nine Pinus sylvestris forests (5–10 ha each) in southern Finland. Sites were located in two regions: (1) in eastern region with shorter management history and (2) in western region where intensive forestry has continued longer. We evaluated whether restoration of dead/burned wood is beneficial for rare and conservation‐dependent species and measured the recovery of pyrophilous and red‐listed insects (beetles and flatbugs) in burned forests, using standardized sampling effort. Altogether, 956 individuals of 29 red‐listed and pyrophilous species were sampled. Results Rare species colonized areas quickly, but there was a clear difference in species richness between the regions. The eastern forests harboured higher species richness after restoration. In these sites, the average species richness was 13.7 species per site, whereas in western forests it was 5.0 species per site. Similar pattern was also observed in subgroups: the corresponding numbers for pyrophilous species were 9.7 vs. 3.8, for red‐listed 8.7 vs. 2.3 and for red‐listed pyrophiles 4.7 vs. 1.2. Main conclusions Introducing fire back to boreal forests can aid in the recovery of rare species, but the landscape context considerably affects the success of restoring species. If restored habitats are located in landscapes that have lost their natural properties long ago, the success of restoration seems to be more challenging than in landscapes where habitats have been modified more recently.     

Presidential Address—Some Reflections On The Nature Of Species

Background: Variation in the distribution and abundance of woody plants as consequence of disturbances such as fire may be explained by lineage age.

Aims: We tested whether lowland tropical tree lineages that colonise secondary forests are more late-diverging than clades from old-growth forests, and whether tree phylogenetic beta diversity from old-growth to secondary forests is higher in burned than non-burned secondary forests.

Methods: We sampled tree communities in old-growth forests and in secondary forests with distinct disturbance histories (burned and unburned). We calculated mean family age in each plot, and tested for differences among forest types using ANOVA. A phylogenetic fuzzy-weighting procedure was employed to generate a matrix describing the abundance of tree clades per plot, which was then analysed using a principal coordinate analysis.

Results: Most clades found in old-growth forests were underrepresented in secondary forests, which have been heavily colonised by a single species from a young lineage that is not found in old-growth forests. Phylogenetic beta diversity was higher between unburned secondary forests and old-growth forests than between burned secondary forests and old-growth forests.

Conclusions: The capacity of Neotropical trees to colonise secondary forests and persist after fire disturbance may be related to the age of distinct lineages.     

Winter tourism increases stress hormone levels in the Capercaillie Tetrao urogallus

Montane and alpine habitats in Europe remained relatively undisturbed until the beginning of the last century. Today, outdoor recreation activities are a major economic factor in alpine regions. Many tourism areas coincide with winter habitats of shy and endangered species. The Western Capercaillie Tetrao urogallus has suffered from rapid population declines during recent decades over much of its range. In central Europe, many Capercaillie are exposed to intensive human recreation activities in their habitats, which may contribute to this decline. However, little is known about their susceptibility to human recreation activities. This study assessed whether human recreation in winter evokes physiological stress responses in several populations of Capercaillie. During two winters, we sampled 1130 Capercaillie droppings in Germany and Switzerland of populations at various distances from winter recreation activities and measured concentrations of faecal corticosterone metabolites. Capercaillie in relatively dense and homogeneous mountain forests dominated by Norway Spruce Picea abies showed markedly increased stress hormone levels closer to locations with winter recreation activity. However, this physiological response to human recreation was not detectable in forests dominated by various pine species and a heterogeneous structure. Capercaillie may be particularly sensitive to recreation because any factor affecting their fine‐tuned physiological and behavioural adaptations to survive under harsh winter conditions may lead to harmful fitness costs.     

Size matters in regulating the biodiversity of tropical forest soils

Tropical forests have long fascinated ecologists, inspiring a plethora of research into the mechanisms regulating their immense biodiversity, which originally captured the interests of early natural historians and explorers, and that still persists to this day. A new focus of this research emerged in the early 2000s highlighting the potential role of neutral (stochastic) processes in regulating the composition and diversity of tropical forest communities, and thus the maintenance of a large portion of global biodiversity (Hubbell, 2001). This strictly contrasted the long‐held belief that communities assembled via the sorting of species (and their abundances) via a deterministic response to local abiotic and biotic environmental conditions, reflecting the niche of each species (Leibold & McPeek, 2006). Yet, it is unlikely that the assembly of any community is solely governed by either stochastic or deterministic processes, but instead a combination of both. However, whether deterministic processes via niche‐based environmental sorting of species, or stochastic processes reflecting pattens of dispersal limitation, neutral effects and ecological drift dominate is often unclear. This prompts questions as to whether the relative influence of one process over another is dependent on the scale (spatial or temporal) or context of the study, or specific traits of the taxa under investigation (e.g., body size). In a From the Cover paper in this issue of Molecular Ecology, Zinger et al. (2018) tackle all these issues and show, among other things, that for soil microbes and mesofauna from tropical forests, the relative contribution of stochastic and deterministic processes in assembling their communities is strongly dependent on the body size or the studied taxa.     

森林干扰生态研究

陆地上80％的生态系统都已受到了来自人类和自然的各种干扰,森林生态系统也不例外．在各种干扰作用下,尤其是人类不合理的干扰导致世界范围内的森林退化／衰退已成为一个十分严峻的事实,因此,以维持、恢复森林生态系统固有的多种功能为基础,实现高效、稳定、可持续就成为经营森林生态系统的总目标．随着干扰的加剧,近年来生态学界更加关注的是“受干扰”生态系统的研究．干扰对森林生态系统主要生态过程的影响以及森林生态系统对干扰的响应等问题,已成为森林生态研究领域的国际前沿与热点．因此,系统地研究干扰条件下森林生态系统的生态过程,并在此基础上确立干扰森林的经营理论与技术,对中国天然林资源保护等林业工程实施及国家生态安全建设具有重要的科学和现实意义．本文在广泛收集国内外有关森林干扰研究结果的基础上,总结了森林干扰的基本概念,分析了干扰与森林经营的关系,探讨了森林干扰研究领域所涉及的内容和关注的基础问题,提出了森林干扰生态研究的主要内容与方向,对今后干扰森林生态研究和中国天然林保护等林业工程建设具有参考价值．     

Landscape host abundance and configuration regulate periodic outbreak behavior in spruce budworm Choristoneura fumiferana

Landscape‐level forest management has long been hypothesized to affect forest insect outbreak dynamics, but empirical evidence remains elusive. We hypothesized that the combination of increased hardwood relative to host tree species, prevalence of younger forests, and fragmentation of those forests due to forest harvesting legacies would reduce outbreak intensity, increase outbreak frequency, and decrease spatial synchrony in spruce budworm Choristoneura fumiferana outbreaks. We investigated these hypotheses using tree ring samples collected across 51 sites pooled into 16 subareas distributed across a large ecoregion spanning the international border between Ontario (Canada), and Minnesota (USA). This ecoregion contains contrasting land management zones with clear differences in forest landscape structure (i.e. forest composition and spatial configuration) while minimizing the confounding influence of climate. Cluster analyses of the 76‐yr time‐series generally grouped by subareas found within the same land management zone. Spatial nonparametric covariance analysis indicated that the highest and lowest degree of spatial synchrony of spruce budworm outbreaks were found within unmanaged wilderness and lands managed at fine spatial scales in Minnesota, respectively. Using multivariate analysis, we also found that forest composition, configuration, and climate together accounted for a total of 40% of the variance in outbreak chronologies, with a high level of shared variance between composition and configuration (13%) and between composition and climate (9%). At the scale of our study, climate on its own did not explain any of the spatial variation in outbreaks. Outbreaks were of higher frequency, lower intensity, and less spatially synchronized in more fragmented, younger forests with a lower proportion of host species, with opposing outbreak characteristics observed in regions characterised by older forests with more concentrated host species. Our study is the first quantitative evaluation of the long‐standing ‘silvicultural hypothesis’ of spruce budworm management specifically conducted at a spatio‐temporal scale for which it was intended.     

The density and diversity of gymnamoebae associated with terrestrial moss communities (Bryophyta: Bryopsida) in a northeastern U.S. forest

Moss communities are commonly found in temperate forests and form a nearly continuous understory in some high latitude forests. However, little is known about the microbial component of these communities, especially the non-testate amoeboid protists. Fifty morphospecies of naked amoebae were identified in samples collected at eight sites in a northeastern North American forest. The mean number (+/-SE) of morphospecies found per sample site based on laboratory cultures was 17+/-2.1. The density of amoebae expressed as number/g dry weight of moss ranged from 3.5+/-0.04 x 10(3) to 4.3+/-0.2 x 10(4) and was positively correlated with the moss moisture content (r=0.9, P<0.001, df=26). Densities of gymnamoebae in the moss are generally higher than found in the surrounding soil, but this may be due in part to the greater weight of soil per unit volume compared with moss. The percentage of encysted forms was inversely related to the moisture content of the moss sample.     

Road-associated edge effects in Amazonia change termite community composition by modifying environmental conditions

Roads and road-building are among the most important environmental impacts on forests near urban areas, but their effects on ecosystem processes and species distributions remain poorly known. Termites are the primary decomposer organisms in tropical forests and their spatial distribution is strongly affected by vegetation and soil structure. We studied the impacts of road construction on termite community structure in an Amazonian forest fragment near Manaus, Brazil. One leading question was whether the fragment under study was large enough to maintain the termite species pool present in nearby continuous forests. We also asked how soil moisture and canopy openness varied with proximity to roads, and whether these changes were associated with changes in termite species richness and composition in the fragment. While the forest fragment had a termite composition very similar to that of continuous forests, roads caused important changes in soil moisture and canopy openness, especially when close to forest edges. At distances of up to 81 m from roads, changes in soil moisture were significantly related to changes in termite species composition, but there was no correlation between canopy openness and species richness or composition. These results suggest that fragmentation caused by roads impacts termites in a different and less damaging manner than fragmentation caused by other kinds of degradation, and that even fragments bisected by roads can support very diverse communities and even undescribed taxa of termites. We conclude that a buffer zone should be established for conservation purposes in the reserves surrounded by roads.     

The relative importance of intrinsic and extrinsic factors in the decline of obligate seeder forests

Forests that regenerate exclusively from seed following high‐severity fire are particularly vulnerable to local extinction if fire frequency leaves insufficient time for regenerating plants to reach sexual maturity. We evaluate the relative importance of extrinsic (such as fire weather and climate cycles) and intrinsic (such as proneness to fire due to stand age and structural development) factors in driving the decline of obligate seeder forests. We illustrate this using obligate seeding alpine ash (Eucalyptus delegatensis) forests in the montane regions of Victoria, Australia, that were burnt by megafires in 2003 (142,256 ha) or 2007 (79,902 ha), including some twice‐burnt areas (11,599 ha). Geospatial analyses showed only a small effect of stand age on the remote sensing estimates of crown defoliation, but a substantial effect of forest fire weather, as measured by forest fire danger index (FFDI). Analysis of meteorological data over the last century showed that 5‐year increases in FFDI precede cycle major fires in the E. delegatensis forests. Such strong extrinsic climate/weather driving of high‐severity fires is consistent with the ‘interval squeeze model’ that postulates the vulnerability of obligate seeder forests to landscape‐scale demographic collapse in response to worsening fire weather under climate change.     

Mediterranean vegetation dynamics: modelling problems and functional types

Gap models have been applied to a wide range of ecosystems, mainly temperate and boreal forests, but rarely have such models been applied to Mediterranean ecosystems. In the present review we address some problems of gap models for predicting the long-term dynamics of Mediterranean ecosystems, and we suggest plant functional types suitable for modelling based on responses to disturbance. Most gap models do not take into account different life forms, interactions with fire (e.g., resprouting and stimulation of the germination), and underground structures. Long term human impact on Mediterranean ecosystems has made a significant impact on the current landscapes. That intense land use, involving long-lived slow-growing species, has had long-term consequences. It is not possible to understand Mediterranean vegetation and to validate any model without considering these factors. The lack of data for Mediterranean species may be overcome by taking into account correlations of traits and trade-offs between different functional types. A simple disturbance-based functional group system is discussed.     

Seed dispersal mechanisms and the vegetation of forest islands in a West African forest-savanna mosaic (Comoé National Park,Ivory Coast)

The transition zone between forest and savanna is typically characterized by a dynamic patchwork of forest and savanna. We studied the woody plant species composition of 49 forest islands, 18 savanna, and 3 gallery forest plots in the Comoé National Park (Ivory Coast), West Africa's largest savanna reserve. TWINSPAN makes a clear distinction in vegetational composition between these three major habitat types but, nevertheless, more than 50% of the 292 species occur in at least 2 of them. The gallery forest is dominated by Cynometra megalophylla (Caesalpiniaceae), a genus known to dominate humid forests in other afrotropical regions. Ordination reveals four distinct categories of forest islands, (1) humid forests comparable to the gallery forest in their species composition, (2) dry disturbed and (3) dry undisturbed forests and (4) forests formerly inhabited by humans. Disturbed forests harbor more savanna species but also a distinct group of disturbance-tolerant forest species. Compared to other forest species, in this latter group we found an exceptionally high fraction of animal dispersed species (80% vs. 58%), while wind dispersed species or species lacking long distance seed dispersal mechanisms were correspondingly rare. This pattern occurs in spite of the fact that the frequency of wind dispersed species in general increases from dense humid forests to open dry forests and savanna. Species lacking long distance dispersal mechanisms are most abundant among those specialized on humid forests. These observations suggest that the species composition of forest islands is to some extent determined by the seed dispersal abilities of the different species.     

Making a living in the tropical forest: Yuquí foragers in the Bolivian Amazon

Questions concerning the availability of resources in tropical rain forests have given rise to the current debate centering on whether human subsistence based solely on foraging is possible in these biomes without agricultural subsidies. This paper takes the position that changing perspectives on ecological pattern and process in tropical forests and the significant variation among tropical forests on a worldwide as well as regional scale must be taken into consideration. Human disturbance is also proposed as a cause of dependence on agriculture by modern human foragers rather than as a necessary precondition for successful exploitation of the tropical forest. These issues are discussed against the background of a case study of the Yuquí, who, until very recently, were true foragers in the Bolivian Amazon. For the Yuquí, the sustainability of their subsistence system depended on a finegrained knowledge of their environment and the freedom of movement over a large territory to access resources within it.     

Sensitivity of tropical forests to climate change in the humid tropics of north Queensland

An analysis using an artificial neural network model suggests that the tropical forests of north Queensland are highly sensitive to climate change within the range that is likely to occur in the next 50–100 years. The distribution and extent of environments suitable for 15 structural forest types were estimated, using the model, in 10 climate scenarios that include warming up to 1°C and altered precipitation from –10% to +20%. Large changes in the distribution of forest environments are predicted with even minor climate change. Increased precipitation favours some rainforest types, whereas decreased rainfall increases the area suitable for forests dominated by sclerophyllous genera such as Eucalyptus and Allocasuarina. Rainforest environments respond differentially to increased temperature. The area of lowland mesophyll vine forest environments increases with warming, whereas upland complex notophyll vine forest environments respond either positively or negatively to temperature, depending on precipitation. Highland rainforest environments (simple notophyll and simple microphyll vine fern forests and thickets), the habitat for many of the region’s endemic vertebrates, decrease by 50% with only a 1°C warming. Estimates of the stress to present forests resulting from spatial shifts of forest environments (assuming no change in the present forest distributions) indicate that several forest types would be highly stressed by a 1°C warming and most are sensitive to any change in rainfall. Most forests will experience climates in the near future that are more appropriate to some other structural forest type. Thus, the propensity for ecological change in the region is high and, in the long term, significant shifts in the extent and spatial distribution of forests are likely. A detailed spatial analysis of the sensitivity to climate change indicates that the strongest effects of climate change will be experienced at boundaries between forest classes and in ecotonal communities between rainforest and open woodland.     

Convergence of bark investment according to fire and climate structures ecosystem vulnerability to future change

Fire regimes in savannas and forests are changing over much of the world. Anticipating the impact of these changes requires understanding how plants are adapted to fire. In this study, we test whether fire imposes a broad selective force on a key fire‐tolerance trait, bark thickness, across 572 tree species distributed worldwide. We show that investment in thick bark is a pervasive adaptation in frequently burned areas across savannas and forests in both temperate and tropical regions where surface fires occur. Geographic variability in bark thickness is largely explained by annual burned area and precipitation seasonality. Combining environmental and species distribution data allowed us to assess vulnerability to future climate and fire conditions: tropical rainforests are especially vulnerable, whereas seasonal forests and savannas are more robust. The strong link between fire and bark thickness provides an avenue for assessing the vulnerability of tree communities to fire and demands inclusion in global models.     

Association between bryophytes and seedlings in Nothofagus sub-Antarctic forests

Bryophytes, which include mosses, liverworts and hornworts, indeed play a significant role in the natural dynamics of native forests. They contribute to fundamental ecological processes such as tree regeneration. In this context, the objective was to analyse the association of bryophytes with Nothofagus seedlings, as well as whether the substrates where bryophytes grew influenced bryophyte-tree seedling association, in sub-Antarctic forests at two contrasting landscapes (coastal and mountain) of Tierra del Fuego (Argentina), to better understand their impacts on the natural regeneration processes. We hypothesized that bryophytes act as a substrate for seed germination and initial regeneration growth in pure and mixed forests of N. pumilio and N. betuloides, resulting in widespread tree seedlings–bryophyte associations in all landscapes. In each forest and landscape location, 60 transects were established (10 m in length) to evaluate bryophyte cover (by point intercept method) and substrate type (bare soil, decaying wood and litter cover) where they were growing. An adaptation of the relative interaction index (RII) based on tree seedling cover associated with bryophyte species (%) and tree seedling cover in the absence of bryophytes (%) was calculated and analysed to assess competition or facilitation between bryophytes and tree seedlings. Nothofagus pumilio seedlings were less abundant in bryophytes compared to other substrates, suggesting an inhibitory effect on the germination and/or survival of N. pumilio. In contrast, the seedlings of N. betuloides, in both pure and mixed forests, exhibited higher abundance on bryophyte substrates, particularly in mosses at mountain landscape (RII = 0.83 ± 0.08 in litter and 0.62 ± 0.11 in decaying wood). These findings suggest that bryophytes play a facilitating role for N. betuloides seedlings during germination and initial phases of growth, mainly in the mountain. Therefore, their conservation promotes N. betuloides forest continuity, both in pure and mixed structures.     

Spatial distribution and temporal dynamics of high‐elevation forest stands in southern Siberia

Aim To evaluate the hypothesis that topographic features of high‐elevation mountain environments govern spatial distribution and climate‐driven dynamics of the forest. Location Upper mountain forest stands (elevation range 1800–2600 m) in the mountains of southern Siberia. Methods Archive maps, satellite and on‐ground data from1960 to 2002 were used. Data were normalized to avoid bias caused by uneven distribution of topographic features (elevation, azimuth and slope steepness) within the analysed area. Spatial distribution of forest stands was analysed with respect to topography based on a digital elevation model (DEM). Results Spatial patterns in mountain forests are anisotropic with respect to azimuth, slope steepness and elevation. At a given elevation, the majority of forests occupied slopes with greater than mean slope values. As the elevation increased, forests shifted to steeper slopes. The orientation of forest azimuth distribution changed clockwise with increase in elevation (the total shift was 120°), indicating a combined effect of wind and water stress on the observed forest patterns. Warming caused changes in the forest distribution patterns during the last four decades. The area of closed forests increased 1.5 times, which was attributed to increased stand density and tree migration. The migration rate was 1.5 ± 0.9 m year^–1, causing a mean forest line shift of 63 ± 37 m. Along with upward migration, downward tree migration onto hill slopes was observed. Changes in tree morphology were also noted as widespread transformation of the prostrate forms of Siberian pine and larch into erect forms. Main conclusions The spatial pattern of upper mountain forests as well as the response of forests to warming strongly depends on topographic relief features (elevation, azimuth and slope steepness). With elevation increase (and thus a harsher environment) forests shifted to steep wind‐protected slopes. A considerable increase in the stand area and increased elevation of the upper forest line was observed coincident with the climate warming that was observed. Warming promotes migration of trees to areas that are less protected from winter desiccation and snow abrasion (i.e. areas with lower values of slope steepness). Climate‐induced forest response has significantly modified the spatial patterns of high‐elevation forests in southern Siberia during the last four decades, as well as tree morphology.     

Transition along gradient from warm to mesic temperate forests evaluated by GAMM

Aims The aim of the study was to discover what set of variables best explains the transition from warm to mesic forest vegetation. Based on various variables grouped into sets (geomorphological, ecological, structural, soil characteristics and chorological), six models were built and tested by generalized additive mixed models (GAMMs). We assumed that each set of variables has different explanatory power. Our aim was to compare the six different models (sets of variables), to test which model best explains the species turnover in forest communities along the transition between warm and mesic temperate forests and to try to find reasons for the different explanatory power of the models.Methods The research took place in the southern part of the Balkan Peninsula. Field sampling was done according to standard methods. The gradient from warm to mesic forests was defined as the turnover of species and evaluated by projection of samples on the first unconstrained DCA axis. Geomorphological, ecological, structural and soil characteristics, together with chorological sets of variables, were regressed on the turnover of species composition. Based on the five sets of variables, six models were constructed and tested by generalized additive mixed models.Important findings Ecological conditions best explain the change of forest communities along the gradient; evolution and the development of vegetation reflected in chorotypes are also of high importance; geomorphology and structure seem not to change so dramatically and soil shows the least significant differences of all. Ecological variables are the most important set of variables in the transition between warm and mesic temperate forests but eco-evolutionary dynamics after the Pleistocene should also be taken into consideration.     

Local and Regional Variation in Local Frequency of Multiple Coffee Pests Across a Mosaic Landscape in Coffea arabica's Native Range

Shaded coffee has been highlighted for its potential to conserve biodiversity, and thus perhaps also a diversity of natural enemies that could control pest organisms. In southwestern Ethiopia, coffee is grown in shade both in contiguous forests and in forest patches with native trees surrounded by open fields. We hypothesized that coffee grown in contiguous forests, which is the natural habitat for coffee (Coffea arabica) and its interacting organisms, would have less pest damage due to high protection by natural enemies. We surveyed pests on coffee plants in plots within contiguous forests (10 sites) and in forest patches (21 sites). In general, the variation in number of damaged or attacked leaves by individual insect or fungal pests was larger between plants than between plots, which suggests that very local conditions or processes are important. The spatial signals were generally weak. Coffee rust and coffee blotch miner tended to have lower infestation rates in accordance with our hypothesis, while fruit flies in ripe berries were more abundant in forest patches closer to contiguous forest. Based on interviews, olive baboons showed a clear dependency on contiguous forest habitat and were regarded as a problem only in contiguous forests and forest patches close to contiguous forests. In conclusion, we found no support for a generally stronger top‐down control on coffee pests in sites within, or with connectivity to, contiguous moist afromontane forests in the native range of coffee.     

An Ecological Basis for Integrated Environmental Management

Historically, approaches to environmental management activities have been reactive rather than proactive. Environmental laws and regulations have been generated primarily in response to particular issues (e.g., chemical contamination), creating a piecemeal approach for managing the environment. Responsibilities for managing different resources (e.g., water, air, forests, wildlife) have been assigned to different agencies or groups within government, further fragmenting environmental management. Proactive approaches that recognize the interconnectedness of environmental components are necessary to address complex and long-term environmental management issues. This Perspective proposes an environmental management approach that is comprehensive and systematic, while still being comprehensible to decision-makers and other stakeholders. The proposed approach is based on ecology and environmental values related to decision-making. It considers interrelationships among and between living organisms (including humans) and their physical environment. The proposed approach builds on the ecological risk assessment (ERA) paradigm, including goal (or problem) identification, values identification (ecological and human) for the environment being managed, and data collection and analysis focused on management decision-making. Stakeholder involvement and active participation are essential elements. As demonstrated herein, application of the proposed framework has enabled environmental managers to achieve workable solutions and to avoid or resolve environmental conflicts at both local and regional scales. The proposed framework is demonstrably transportable across political boundaries, applicable to all environments involving natural resources, independent of any particular ideology, and applicable to environmental management activities at all scales.