Undisturbed Stands Research Articles

Differential Responses of Bilberry (Vaccinium myrtillus) Phenology and Density to a Changing Environment: A Study from Western Carpathians.

Environmental factors regulate the regeneration of mountain spruce forests, with drought, wind, and bark beetles causing the maximum damage. How these factors minimise spruce regeneration is still poorly understood. We conducted this study to investigate how the phenology and population dynamics of bilberry (Vaccinium myrtillus L.), a dominant understory species of mountain spruce forests, are related to selected environmental factors that are modified by natural disturbances (bark beetle and wind). For this, we analysed bilberry at different sites affected by bark beetles and adjacent undisturbed forests in the Tatra National Park (TANAP) during the growing season (April-September) in 2016-2021, six years after the initial bark beetle attack. The observations were taken along an altitudinal gradient (1100-1250-1400 m a.s.l.) in two habitats (disturbed spruce forest-D, undisturbed spruce forest-U). We found that habitat and altitude influenced the onset of selected phenological phases, such as the earliest onset at low altitudes (1100 m a.s.l.) in disturbed forest stands and the latest at high altitudes (1400 m a.s.l.) in undisturbed stands. Although there were non-significant differences between habitats and altitudes, likely due to local climate conditions and the absence of a tree layer, these findings suggest that bilberry can partially thrive in disturbed forest stands. Despite temperature fluctuations during early spring, the longer growing season benefits its growth.

Soil Respiration after Bark Beetle Infestation along a Vertical Transect in Mountain Spruce Forest

In recent decades, large-scale forest disturbances such as windthrow and bark beetle infestations have significantly impacted Earth’s carbon balance and forest ecosystems. This impact alters soil respiration (SR), along with decreased gross primary productivity. To investigate the impact of bark beetle (Ips typographus L.) infestations in mountain spruce forests on SR, we measured SR at sites infested by bark beetles and adjacent undisturbed stands in the Tatra National Park (Slovakia) during the vegetation period (May–September) in 2016–2017 five to six years after the initial bark beetle attack. The measurements were taken along an altitudinal gradient (1100–1400 m a.s.l.). The highest rates of SR were observed during the summer months in both years (from June to August). However, yearly SR from May to September at infested sites showed significantly higher rates than uninfested ones in both years. SR showed a decreasing pattern with elevation gain in 2016 at infested sites, but this pattern was not observed in 2017. This study provides important insights into the impact of bark beetle infestations on SR and emphasizes the need for further research on the long-term effects of forest disturbances on carbon cycling. It also underscores the importance of determining the effect of different components of SR on the changed environment due to bark beetle attacks on mountain spruce forests.

Tree regeneration potential in urban spruce-dominated forests is shaped by management history

With projected climate change, urban spruce-dominated forests are facing increasing risks of forest damages, encouraging management for mixed stand structures. In the major cities of southern Finland, forests are preferentially maintained continuously covered, and tree regeneration is mostly reliant on naturally emerging sapling stock. To understand the role of forest management in shaping natural tree regeneration in urban forests, we studied the occurrence and abundance of tree saplings in spruce-dominated tree stands on a management continuum ranging from partially logged to undisturbed near-natural stands. Study sites (N = 74) were located in three urban centers in southern Finland: Tampere, Lahti and Helsinki region. We analyzed the data by comparing tree regeneration potential between management classes reflecting the timing and intensity of past logging, and by relating the occurrence of saplings with current structures of the living tree stand.Compared to undisturbed stands, partially logged sites had increased regeneration of broad-leaved trees and repressed regeneration of spruce, while the most abundant sapling tree species across all management classes was rowan. We conclude that partial logging can be a successful way of directing tree regeneration towards lower dominance of spruce. However, when the canopy is only partially opened, created gaps may end up being filled primarily by rowans that are comparatively shade-tolerant. Because the ingrowth of rowan and many other broad-leaved tree species is strongly restricted by dense populations of large browsing animals in non-urban areas, urban forests may develop stand structures and tree species composition that are otherwise rare in the Fennoscandian boreal forests.

Population Density and Stability of Breeding Birds in English Oak Woodland Over a 32-Year Period in Relation to Habitat Structure and Edges

Long-term breeding bird censuses in Białowieża National Park (BNP), north-east Poland, have revealed rather low densities of birds and high community stability which may be features of near-natural forest conditions. This paper reports on a long-term census of breeding birds in 50 ha of oak woodland in central England which contained both managed and undisturbed areas. New information is provided on breeding bird density and its spatial variation within English mature broadleaved woodland to address two questions: Under what circumstances are English woods likely to support higher densities than those occurring in BNP? Is there evidence that population and community stability is lower in English woodland? The overall bird density was lower than in the BNP oak-hornbeam stands, at the scale of both the whole study area and the undisturbed stands. Densities of three of the five dominant species (Cyanistes caeruleus, Parus major, Troglodytes troglodytes) were lower in BNP, Fringilla coelebs was higher, while Erithacus rubecula was similar. Within the undisturbed stands, densities of seven of 12 species, including T. troglodytes, were similar to those in BNP, two were considerably higher (C. caeruleus, P. major) and one much lower (F. coelebs). Selection of the external woodland edge by several species resulted in relatively high overall densities in the edge zone. The broad composition of the bird community remained fairly stable with the exception of declines in tropical migrants and increases in shrub layer nesters. Temporal abundance patterns of species showed much individuality. Trends of several species appeared to be driven by changes in habitat structure. However, the same species remained numerically dominant or characteristic of the wood throughout the study period. This suggests there was a core of resilient species, much as proposed for BNP. Although caution is needed in drawing conclusions from a single site, with the exception of a small number of species, in recent decades there is unlikely to have been a general pattern of higher densities of birds in English woodland than in BNP. However, some English woods with highly complex vegetation structures, or a high proportion of edge habitat, do have exceptionally high densities (> 100 territories/10 ha).

Implications of community forest management for the conservation of the genetic diversity of big-leaf mahogany (Swietenia macrophylla King, Meliaceae) in the Maya Biosphere Reserve, Petén, Guatemala

Community Forest Management in the Maya Biosphere Reserve (MBR; Petén, Guatemala) has been recognized internationally for yielding forest conservation and socioeconomic benefits. However, the effect of current timber harvesting practices on the genetic diversity of timber species populations has not previously been documented. This study assessed the effects of timber harvesting on the genetic diversity and viability of regeneration of the most commercially important timber species in the MBR: big-leaf mahogany (Swietenia macrophylla King). Trees and seeds were sampled for two consecutive years in two Forest Management Units of the Multiple Use Zone (MUZ) of the MBR: Cruce a la Colorada and Carmelita. We correlated genetic diversity parameters (as measured using nuclear microsatellites) with seed germination percentages and compared genetic diversity of adults and seeds in stands that had been affected by timber harvesting and those that had not. We found a significant correlation between seed germination percentages (81–83%) and observed heterozygosity (rho=0.27), confirming that genetic diversity is important to regeneration success. No significant differences were found in allelic richness (AR), expected and observed heterozygosity (HE and HO), or inbreeding (FIS), between adults and seeds in harvested vs. undisturbed stands; or before and after timber harvesting. We found low inbreeding levels (FIS=0.040–0.094), low biparental inbreeding (0–0.01), and high outcrossing rates (0.925–0.970) in the populations of S. macrophylla analyzed. Our study therefore provides evidence that genetic diversity in big-leaf mahogany populations was not diminished by one cutting cycle under current practices of community forest management in the MUZ of the MBR.

Tribe Shoreae (Dipterocarpaceae subfamily Dipterocarpoideae) Finally Dissected

SummaryThe dipterocarp tribe Shoreae, perhaps more than any other members of this elegant family of often giant emergent trees, is familiar to all who visit the once ubiquitous lowland forests of tropical Asia. Timbers of the genus Shorea comprised the bulk of hardwood traded on international markets for thirty years, since the nineteen seventies. Distinct species groups came to be recognised by taxonomists: for their characteristic androecia, and sometimes differences in bark and wood anatomy, while generic status for some was then proposed on embryological evidence. A new molecular phylogeny of the family, and this tribe, substantially confirms the embryological case. This paper formalises resultant nomenclatural changes. Those of us who recall the majestic forested former landscapes of the Sunda lands may regret this decision. But now, with landscapes irretrievably changed by serried ranks of oil palm and forest degradation, the case for recognition of the proposed new entities can guide conservation planners in recognising and making the case for permanently conserving surviving undisturbed stands of exceptional composition or diversity.

Infestation patterns of incipient red turpentine beetle populations in fire-affected, logged and undisturbed forest stands of northern China

The red turpentine beetle (RTB) Dendroctonus valens is an alien invasive bark beetle that has become one of the most important pests of pine forests in China. In recent years, RTB has spread to the Heilihe area of northern China, where, within a short period of time, its population density has reached an incipient level. Understanding the attack behavior of RTB in the early stages of an infestation can help contain its population and avoid the transition from incipient to outbreak levels. In addition, numerous wildfires and illegal selective logging events in the Heilihe area give us the opportunity to study the attack behavior of RTB in forest stands with different disturbances. In the present study, we explored the infestation pattern of RTB in 20 wildfire-disturbed forests, 19 selectively logged forests and 42 undisturbed forests at the incipient population level. We measured stand and landscape-level variables, including stand mean diameter at breast height (DBH), canopy cover, aspect, elevation, slope and host connectivity. The landscape-level variable of host connectivity was extracted from a Sentinel-2 image through graph theory. In disturbed stands, we also measured bole scorch height and the number of stumps as proxies for fire and logging intensity. Generalized linear models were used to determine the relative importance of these explanatory variables in RTB infestations. Our results showed that wildfire-disturbed and logged stands had higher RTB infestation levels than undisturbed stands and disturbance intensity was the most important predicting variable across all factors. Furthermore, stand mean DBH had a positive relationship with RTB attacks in disturbed stands. In undisturbed stands, stand-level factors such aspect and canopy cover were the main driving factors of RTB attacks rather than host connectivity. However, the role of host connectivity shifted in wildfire-disturbed stands with high fire intensity, where interconnected stands promoted RTB infestations at the 500 m and 700 m scales. Our findings are valuable for identifying stands that are more vulnerable to RTB attacks and prioritizing management interventions aimed at controlling beetle populations.

Insect infestations and the persistence and functioning of oak-pine mixedwood forests in the mid-Atlantic region, USA.

Damage from infestations of Lymantria dispar L. in oak-dominated stands and southern pine beetle (Dendroctonus frontalis Zimmermann) in pine-dominated stands have far exceeded impacts of other disturbances in forests of the mid-Atlantic Coastal Plain over the last two decades. We used forest census data collected in undisturbed and insect-impacted stands combined with eddy covariance measurements made pre- and post-disturbance in oak-, mixed and pine-dominated stands to quantify how these infestations altered forest composition, structure and carbon dynamics in the Pinelands National Reserve of southern New Jersey. In oak-dominated stands, multi-year defoliation during L. dispar infestations resulted in > 40% mortality of oak trees and the release of pine saplings and understory vegetation, while tree mortality was minimal in mixed and pine-dominated stands. In pine-dominated stands, southern pine beetle infestations resulted in > 85% mortality of pine trees but had minimal effect on oaks in upland stands or other hardwoods in lowland stands, and only rarely infested pines in hardwood-dominated stands. Because insect-driven disturbances are both delaying and accelerating succession in stands dominated by a single genus but having less effect in mixed-composition stands, long-term disturbance dynamics are favoring the formation and persistence of uneven age oak-pine mixedwood stands. Changes in forest composition may have little impact on forest productivity and evapotranspiration; although seasonal patterns differ, with highest daily rates of net ecosystem production (NEP) during the growing season occurring in an oak-dominated stand and lowest in a pine-dominated stand, integrated annual rates of NEP are similar among oak-, mixed and pine-dominated stands. Our research documents the formation of mixedwood stands as a consequence of insect infestations in the mid-Atlantic region and suggests that managing for mixedwood stands could reduce damage to forest products and provide greater continuity in ecosystem functioning.

Distribution, Dominance Structure, Species Richness, and Diversity of Bats in Disturbed and Undisturbed Temperate Mountain Forests

The increase in mean annual temperature and reduction in summer rainfall from climate change seem to increase the frequency of natural and human-made disturbances to forest vegetation. This type of rapid vegetation change also significantly affects bat diversity. The aim of our study was to document differences in the ecological parameters of bat assemblages in different types of temperate mountain forests, particularly between disturbed and undisturbed coniferous and deciduous forests. Additionally, these issues were considered along an elevation gradient. We mist netted bats on 73 sites, between 931 and 1453 m elevation, in the forests of the Tatra Mountains in southern Poland. During 2016–2020, 745 bats, representing 15 species, were caught. The most abundant were Myotis mystacinus (Kuhl, 1817) (53.0%) and M. brandtii (Eversmann, 1845) (21.5%). We observed differences in species diversity, elevational distribution, and dominance between different types of forests and forest zones. Species richness peaked at around 1000–1100 m elevation. The highest species richness and other indices were observed in undisturbed beech stands, although they constituted only about 2.7% of the forest area. The lowest species diversity was observed in disturbed coniferous forests, in both the lower and upper forest zone. The species richness and dominance structure of bat assemblages were also found to depend on the location above sea level. In some bat species, the sex ratio was higher at higher elevations, and differences in the sex ratio in a few bat species, between different types of forests, were observed. Our findings suggest that disturbed, beetle-killed spruce forests are an unsuitable environment for some bat species.

Spatial pattern and interspecific association of tree species in coniferous and deciduous broad-leaved mixed forest under different disturbance intensities

We explored the effects of disturbance densities on the spatial pattern and the association of tree species in the coniferous broadleaved mixed forest in Pangquangou Nature Reserve of Guandi Mountain. Using three factors including canopy density, stand density and number of stumps, we classified the disturbance intensities of different forest stands into three levels, non-disturbance, moderate disturbance, and severe disturbance. The spatial distribution pattern and the association of different tree species were analyzed by spatial point pattern K2 function. The results showed that the diameter distribution of trees in undisturbed plots was inverted 'J' type, while that of moderate disturbance and serious disturbance plots was under bimodal curve distribution. The stand distribution pattern showed a small-scale aggregated distribution under undisturbed and moderately distur-bance, and a random distribution under heavy disturbance. At the small scale, the coniferous and broadleaved species showed no correlation in undisturbed stands, were positively correlated in moderately disturbed stands, and negatively correlated in seriously disturbed stands. At large scale, they were no correlated in both moderately and seriously disturbed stands. The results suggested that abundance of trees with small diameter in the forests was negatively with disturbance intensity, which led to the lower degree of intraspecific aggregation at small scale. Meanwhile, appropriate levels of disturbance would benefit the collaborative use of environmental resources for trees. Our results revealed the impacts of disturbance density on forest community structure and could provide theoretical basis for forest management.

Рост вегетативных органов Picea abies (L.) Karst. в антропогенной среде

The studies were carried out in stands of various degree of devastation: in the city, suburban forests and forests of the green zone. Recreational loads strongly affect the sanitary condition of spruce forests. The number of healthy trees decreases to 30–42 % with increasing recreational digression, while the number of declining and dead trees increases to 15–36 %. The state of tree stands in the forests of the green zone is estimated at 1.2–1.5 points, and 2.1–2.7 points in the suburban forests. No declining and dead trees were found in the forests of the green zone, and in the suburban forests their share was 15 and 36 % of the total number, respectively. Therefore, generally, spruce suburban forests are classified as weakened. Approximately 59 % of the area of suburban forests is in the III stage of recreational digression, and 19 % – in the IV stage. Growth studies of P. abies showed that the features of these processes are determined mainly by the seasonal variability of climatic factors. Studies have shown that the features of growth processes of P. abies are determined mainly by seasonal variation of meteorological factors. It was found that the earliest growth of shoots and needles begins and ends in the urban environment. The year-by-year variability in the timing of these phenophases reaches 1–2 weeks. Soil compaction as a result of recreational loads has a particularly negative effect on the intensity of tree growth and annual growth of vegetative organs. Shoots of P. abies in green forests (undisturbed stands) are longer than in suburban and urban plantations by 2–30 % and 6–17%, respectively. The longest needles (16.6–19.7 mm) are formed in the forests of the green zone. In urban plantations this value is 12.8–15.0 mm. The smallest needle packing was found in the city conditions, characterized by the maximum degree of recreational digression. Here, the annual radial increment of the trunk of P. abies under the influence of recreational loads decreases by 16–20 % compared to the forests of the green zone. The sequence in the growth phenophases does not depend on the degree of environmental disturbance. The shoots are the first to grow (in May), young needles after 1 or 2 weeks, and then the formation of wood in the lower part of the trunk begins. The sequence in stopping the growth processes is as follows: shoots, needles, trunks. For citation: Kishchenko I.T., Olkhina E.S. Growth of Vegetative Organs of Picea abies (L.) Karst. in Anthropogenic Environment. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 3, pp. 59–72. DOI: 10.37482/0536-1036-2021-3-59-72

Effects of elevation and disturbances on the associations between the diversities of bryophyte and macrolichen functional-taxonomic groups on Madeira Island

Biodiversity varies with elevation and is affected by disturbances. However, little is known about how the associations between the diversities of different bryophyte and macrolichen functional-taxonomic groups are altered along elevational gradients and by disturbances. Knowledge on the associations between these functional-taxonomic groups might be of importance in practical conservation biology, as identifying indicator taxa which are easy to monitor could be useful in estimating a wider biodiversity. We sampled the species richness of bryophytes and macrolichens in 92 plots distributed in disturbed and undisturbed stands along elevational gradients in the laurel forest of Madeira. We then calculated a matrix of correlations for all pairwise combinations of 18 different functional-taxonomic bryophyte and macrolichen groups and tested for average differences in correlations with elevation and disturbance history and whether particular functional-taxonomic groups can be used to estimate the richness of other taxa. Associations between the diversities of functional-taxonomic groups within the bryophyte group and within the macrolichen group were always positive and mainly strong. Although changes in elevation and disturbance history changed the associations between the different bryophyte and macrolichen functional-taxonomic groups, we found the species richness of mosses or liverworts to be suitable for predicting overall bryophyte species richness and the species richness of green-algae macrolichens to be reliable for estimating overall macrolichen species richness. Associations between diversities of bryophyte and macrolichen groups were generally weak, suggesting that the two groups have different ecological requirements and do not share the same environmental drivers. The fact that no single bryophyte taxon can be used to predict the richness of any macrolichen group, and vice versa, points to the need to study both bryophytes and lichens. However, we found indicator taxa that are relatively easy to monitor and therefore could be used to estimate the wider biodiversity.

Machinery-Induced Damage to Soil and Remaining Forest Stands—Case Study from Slovakia

The paper deals with the damage of the remaining stand and soil caused by harvesting using three ground-based forest operations methods (harvester-forwarder/cable skidder/animal-tractor). It compares the impact of the most common harvesting technologies applied in Slovakia and in Central Europe and thus contributes with valuable information to the knowledge on the suitability of their application in forests stands dominated by broadleaved tree species. Harvesting was performed in five forest stands located at the University Forest Enterprise of Technical University in Zvolen in central Slovakia from August to October 2019. Damage to remaining trees was assessed from the point of its size, type, and position of damage along stem. We expected lower damage of remaining trees in stands where harvesters were used because of the applied cut-to-length short wood system and fully mechanized harvesting system. In addition, we examined soil bulk density and soil moisture content in ruts, space between ruts, and in undisturbed stand to reveal the impact of harvesting machinery on soil. We expected greater soil bulk densities and lower soil moisture content in these stands due to the greatest weight of harvesters and in ruts created by machinery compared with undisturbed stand soil. The highest percentage of damaged remaining trees equal to 20.47% and 23.36% was recorded for harvester forest operations, followed by skidder (19.44%) and animal forest operations with 19.86% and 14.47%. Factorial ANOVA confirmed significant higher soil compaction in stands where harvesters were used (higer bulk density) than in stands where skidding was performed with the skidder and animal power. Higher soil moisture content was recorded in ruts created by harvesters and the skidder. The lowest soil moisture content was in undisturbed stands irrespective of the applied forest operation method.

Nutrient enrichment stimulates herbivory and alters epibiont assemblages at the edge but not inside subtidal macroalgal forests

Nutrient enrichment is a major threat to subtidal macroalgal forests. Several studies have shown that nutrient inputs can enhance the ability of opportunistic algal species to acquire space freed by disturbance, at the expense of architecturally complex species that form forests. However, competition between canopy- and turf-forming macroalgae is not limited to the aftermath of disturbance. Canopy-forming macroalgae can provide suitable substratum for diverse epibiont assemblages, including both algae (epiphytes) and sessile invertebrates (epizoans). Despite evidence of enhanced epiphyte loading under eutrophic conditions, few experimental studies have assessed how nutrient enrichment influences the structure of epibiont assemblages on canopy-forming macroalgae at the edge versus inside forests. In oligotrophic waters of the NW Mediterranean, we experimentally tested the hypothesis that nutrient-driven proliferation of opportunistic epiphytic algae would affect the performance of the fucoid, Carpodesmia brachycarpa, and reduce the richness and abundance of the epizoan species they support. We predicted negative effects of nutrient enrichment to be greater at the edge than inside forests and on thalli that had recovered in cleared areas than on those within undisturbed canopy stands. Nutrient enrichment did not affect the photosynthetic efficiency and reproductive output of C. brachycarpa. By contrast, it enhanced herbivore consumption and decreased the cover and diversity of epizoans at forest edges, likely by stimulating the foraging activity of Arbacia lixula, the most abundant sea urchin in adjacent encrusting coralline barrens. Fertilization of areas inside forests had no effect on either C. brachycarpa or epibiont assemblages. Finally, nutrient enrichment effects did not vary between cleared and undisturbed areas. Our results show that moderate nutrient enrichment of oligotrophic waters does not necessarily cause the proliferation of epiphytes and, hence, a strengthening of their competitive effects on canopy-forming macroalgae. Nevertheless, enhanced herbivory damage to fertilized thalli at forest edges suggests that fragmentation could reduce the resilience of macroalgal forests and associated epibiont assemblages to nutrient enrichment.

Modelling the influence of different harvesting methods on forest dynamics in the boreal mixedwoods of western Quebec, Canada

Forest management aims to better understand effects of natural disturbance regimes on forest dynamics and use this knowledge to formulate guidelines in forest planning, thereby narrowing gaps between managed and unmanaged forest landscapes. Using forest simulators to reconstruct forest dynamics in relation to ecosystem processes, including disturbances, could help forest managers to better understand harvesting effects on forest dynamics. Using SORTIE-ND, a spatially explicit forest simulator, we generated stand dynamics for 100 years following simulated clear-cut and partial harvests (dispersed vs aggregated, with 30% and 60% basal area removal). Based on the hardwood: conifer basal area ratio, we grouped post-fire stands into three stand types corresponding to natural post-fire succession (deciduous, mixed deciduous, and mixed coniferous) and assessed long-term effects of clear-cutting and partial harvesting on each. Our results suggest that spatial configurations of harvested and residual trees had a greater effect on stand dynamics than did tree removal intensity. Following dispersed partial harvesting, both deciduous and mixed deciduous stands had species composition and structure similar to unharvested stands of the next successional stage. In these same stand types, aggregated harvests and clear-cutting favoured increased regeneration and basal area increments of aspen, which set succession back to aspen dominance, as has been observed after wildfire. Dispersed partial harvests (both 30% and 60%) and 30% aggregated cuts, in mixed coniferous stands, maintained recruitment and dominance of conifers to levels comparable with unmanaged stands. Clear-cutting in all stand types greatly modified stand compositional and structural attributes, and, when conducted in stands where aspen was abundant, performed as a stand-replacing disturbance, setting succession back to early developmental stages, i.e., to aspen dominance. We conclude that partial harvesting, which emulates gap dynamics similar to undisturbed stands, can maintain natural stand dynamics.

Effects of disturbances in a subalpine forest on its structural indicators and bird diversity

Abstract Due to harsh climatic conditions, a limited number of tree species, and a predominantly single-story structure, subalpine forests are characterized by low faunal diversity. While the habitats of species associated with this altitudinal zone are strongly modified by abiotic and biotic factors, the forest management procedures implemented in the aftermath of disturbances typically focus on sanitary hazards and economic losses rather than benefits to biodiversity. The study involved three areas in different stages of forest development resulting from natural disturbances: mature (closed undisturbed stands), break-up (stands with ongoing break-up processes), and growing-up (stands with advanced post-disturbance regeneration). Forest structural indicators for each stage were evaluated on sample plots. A bird census was conducted during breeding and non-breeding seasons to determine species composition, density, and ecological groups (nesting guilds). Actual species diversity, the maximum Shannon-Wiener diversity index, and the evenness index were calculated for each forest development stage. Finally, similarity indices were computed to compare the various stages in terms of bird species. The processes of stand mortality, deadwood accumulation, and regeneration initiation were the driving forces for the development of new habitat conditions with a substantial expansion of potential nesting and foraging sites and shelters. The forest structural indicators were greatly varied. The mature stage revealed the highest density of breeding bird pairs, but the species composition was simplified, with the lowest evenness indicator. The largest number of nesting bird species was found in the break-up stage. During the non-breeding season, the break-up stage was not preferred by birds; the greatest number of species was observed in the growing-up stage, and the highest density in the mature stage. The bird species composition and similarity indices showed substantial differences between the various stages of forest development. Given the continuity of forest development processes and the related changes, it appears that the various development stages should not be viewed as more or less desirable than others from a conservation perspective. The findings show benefits to biodiversity brought about by disturbances in subalpine forests and the importance of each stage. Thus, management practices should be modified to better focus on the protection of the microsites created by disturbances, which are sparse in undisturbed stands.

Boreal old-growth forest structural diversity challenges aerial photographic survey accuracy

The erosion of old-growth forests in boreal managed landscapes is a major issue currently faced by forest managers; however, resolving this problem requires accurate surveys. The intention of our study was to determine if historic operational aerial forest surveys accurately identified boreal old-growth forests in Quebec, Canada. We first compared stand successional stages (even-aged vs. old-growth) in two aerial surveys performed in 1968 (preindustrial aerial survey) and 2007 (modern aerial survey) on the same 2200 km2 territory. Second, we evaluated the accuracy of the modern aerial survey by comparing its results with those of 74 field plots sampled in the study territory between 2014 and 2016. The two aerial surveys differed significantly; 80.8% of the undisturbed stands that were identified as “old-growth” in the preindustrial survey were classified as “even-aged” in the modern survey, and 60% of the stands identified as “old-growth” by field sampling were also erroneously identified as “even-aged” by the modern aerial survey. The scarcity of obvious old-growth attributes in boreal old-growth forests, as well as poorly adapted modern aerial survey criteria (i.e., criteria requiring high vertical stratification and significant changes in tree species composition along forest succession), were the main factors explaining these errors. It is therefore likely that most of Quebec’s boreal old-growth forests are currently not recognized as such in forest inventories, challenging the efficacy of sustainable forest management policies.

Bryophyte and macrolichen diversity show contrasting elevation relationships and are negatively affected by disturbances in laurel forests of Madeira island

AbstractQuestionsStudies on bryophyte and lichen diversity patterns along elevational gradients are scarce, although this approach can serve as space‐for‐time substitution to predict diversity changes because of climate warming. Therefore, we investigated bryophytes and macrolichens in disturbed and undisturbed stands along an elevational gradient in the unique laurel forest of Madeira island by addressing the following questions: (a) how does the species richness of functional‐taxonomic bryophyte and macrolichen groups differ with elevation; (b) how is the species richness of these groups affected by disturbances?LocationUNESCO World Natural Heritage site laurel forest of Madeira island (Madeira, Portugal).MethodsWe analyzed species richness of bryophytes and macrolichens in 92 plots in response to elevation and to disturbances.ResultsBryophyte species richness showed a mid‐elevational peak, while macrolichen richness increased with elevation. Disturbed plots harbored on average 20% less bryophyte and macrolichen species than undisturbed plots.ConclusionsThe laurel forest of Madeira island is a bryophyte and lichen diversity hotspot. Our findings indicate future biodiversity threats by changing environmental conditions. This calls for the need for a strict protection status of the laurel forest on Madeira island to minimize human‐related disturbances, for the development of management measures that could mitigate climate change effects by maximizing habitat suitability and for the implementation of species conservation programs to prevent future extinctions, in particular of endemic species.

Geographic scale and disturbance influence intraspecific trait variability in leaves and roots of North American understorey plants

AbstractConsidering intraspecific trait variability (ITV) in ecological studies has improved our understanding of species persistence and coexistence. These advances are based on the growing number of leaf ITV studies over local gradients, but logistical constraints have prevented a solid examination of ITV in root traits or at scales reflecting species’ geographic ranges.We compared the magnitude of ITV in above‐ and below‐ground plant organs across three spatial scales (biophysical region, locality and plot). We focused on six understorey species (four herbs and two shrubs) that occur both in disturbed and undisturbed habitats across boreal and temperate Canadian forests. We aimed to document ITV structure over broad ecological and geographical scales by asking: (a) What is the breadth of ITV across species range‐scale? (b) What proportion of ITV is captured at different spatial scales, particularly when local scale disturbances are considered? and (c) Is the variance structure consistent between analogous leaf and root traits, and between morphological and chemical traits?Following standardized methods, we sampled 818 populations across 79 forest plots simultaneously, including disturbed and undisturbed stands, spanning four biophysical regions (~5,200 km). Traits measured included specific leaf area (SLA), specific root length (SRL) and leaf and root nutrient concentrations (N, P, K, Mg, Ca). We used variance decomposition techniques to characterize ITV structure across scales.Our results show that an important proportion of ITV occurred at the local scale when sampling included contrasting environmental conditions resulting from local disturbance. A certain proportion of the variability in both leaf and root traits remained unaccounted for by the three sampling scales included in the design (36% on average), with the largest amount for SRL (54%). Substantial differences in magnitude of ITV were found among the six species, and between analogous traits, suggesting that trait distribution was influenced by species strategy and reflects the extent of understorey environment heterogeneity.Even for species with broad geographical distributions, a large proportion of within‐species trait variability can be captured by sampling locally across ecological gradients. This has practical implications for sampling design and trait selection for both local studies and continental‐scale modelling.A freePlain Language Summarycan be found within the Supporting Information of this article.

Soil enzyme activities increase following restoration of degraded subtropical forests

Ecological restoration increases biodiversity and carbon and nitrogen accumulation. Although soil enzyme activities are critical to element cycling and plant diversity and productivity in natural habitats, little is known regarding the effects of ecological restoration on the activities of soil resident enzymes. We investigated the influence of ecosystem restoration on microbial carbon and nitrogen dynamics in soil, as well as the functionality of five enzymes (catalase, dehydrogenase, polyphenol oxidase, urease, and invertase) via the extraction of samples from stands that were subjected to continuous anthropogenic disturbances (i.e., recurring fuelwood collection and domestic animal grazing) in contrast to samples obtained from stands which were left undisturbed for 6, 11, 21, and 31 years in the subtropical forests of China. We found that soil microbial biomass carbon and nitrogen increased with time since restoration, and the activities of catalase, dehydrogenase, invertase, urease, and polyphenol oxidase were amplified in the undisturbed stands following 11 years of restoration, which continued at high levels or decreased thereafter. Redundancy analysis revealed that enzyme activities were augmented in response to biomass inputs from aboveground litterfall and fine root mortality and were positively related to soil carbon and available nitrogen, phosphorus, and potassium contents. Our results highlight the multiple links between increased aboveground and belowground inputs, the abundance of soil-dwelling microorganisms and their enzyme activities, and their contributions to soil carbon and nutrient cycling following the ecological restoration of degraded subtropical forests.