Temperate Forest Communities Research Articles

Aboveground-belowground linkages across vegetation degradation gradients differ among native eucalypt communities.

Native vegetation degradation impacts soil communities and their functions. However, these impacts are often studied by comparing soil biotic attributes across qualitatively defined, discrete degradation levels within a single plant community at a specific location. Direct quantification of the relationships between vegetation and soil attributes across continuous degradation gradients and at larger scales is rare but holds greater potential to reveal robust patterns in aboveground-belowground linkages that may apply across different plant communities. We investigated how native vegetation attributes relate to soil communities and their functions across a degradation gradient within three native temperate eucalypt woodland and forest communities that differed in soil nutrient availabilities. Across remnant patches of native vegetation in the Sydney Basin bioregion, we established plots representing different levels of decline in their vegetation quality (i.e., increased exotics and canopy changes) compared to relevant reference communities. In those plots, we assessed soil community groups (microbes and fauna), carbon (C) and nutrient cycling (litter decomposition, enzyme activity, and phosphate and nitrate accumulation rates), soil pH, texture and vegetation attributes (composition, structure, and function). Our unique study design revealed that the relationships between vegetation degradation and soil biota across the food web (i.e., AM fungi, Fungi:bacteria ratio, Gram-positive bacteria, total nematodes) were highly dependent on the plant community. However, the degradation impacts on soil functions (i.e., total enzyme activity, and phosphate availability) were mostly consistent, suggesting their potential as belowground indicators of ecosystem degradation, with a notable positive association observed in phosphate availability rates. Additionally, the effects of vegetation degradation on soil biota and their functions appeared stronger in the nutrient-poor plant communities, suggesting greater vulnerability of their belowground components. Our findings call for caution when generalizing belowground responses to degradation and for further research on how nutrient availability mediates the impacts of degradation on aboveground-belowground linkages.

Effects of Nitrogen Addition on Nematode Communities in Northeastern Chinese Forests

Nitrogen deposition has a significant impact on biodiversity and ecosystem functions. However, various mechanisms by which nitrogen deposition affects soil nematode communities in nitrogen-limited temperate forests remain unclear. We conducted long-term nitrogen deposition simulation experiments (including two treatments, control and 50 kg N ha⁻1 yr⁻1) in the Lesser Khingan Range, Greater Khingan Range, and Changbai Mountain, applying nitrogen fertilizer solutions to investigate the effects of long-term nitrogen addition on soil nematode communities in northeastern Chinese forests. Nitrogen addition significantly decreased the total abundance of soil nematodes in the Lesser Khingan Range, Greater Khingan Range, and Changbai Mountain by 20%, 23%, and 18%, respectively. Furthermore, nitrogen addition reduced the α-diversity of soil nematodes and altered the β-diversity indices. The nematode channel ratio increased significantly, while the relative abundance of bacterivores, such as Euteratocephalus, also rose. In contrast, the structure index of the soil nematode community decreased, whereas the basal index increased. These results suggest that nitrogen addition simplifies the soil nematode community structure, which may be an important factor contributing to the decline in ecosystem function. Therefore, we selected soil nematodes as the research subject to provide a scientific basis for the effective protection, sustainable management, and resource utilization of major forest ecosystems in northeastern China under the context of nitrogen deposition.

Cuticular morphology of Schinus L. and related genera

Abstract The Anacardiaceae are a characteristic angiosperm family of the Neotropics where they comprise ~32 genera and 200 species (~80 genera and 800 species globally). Among Neotropical Anacardiaceae genera, Schinus has the greatest species richness with 42 species distributed from tropical latitudes of Brazil and Peru south to the temperate steppe, matorral, and Valdivian temperate forest communities of Patagonia. Previous studies have found some anatomical and morphological leaf traits (e.g. simple vs. compound leaf organization) useful in characterizing lineages within Schinus, but also document traits that are homoplastic within the genus (e.g. stomatal distribution) and convergent among Schinus and its close relatives Lithrea and Mauria (e.g. mesophyll arrangement). Here, we present a survey of leaf cuticular traits in 53 species of Schinus and its closest relatives Lithrea, Mauria, and Euroschinus based on characters observed with scanning electron and optical light microscopy. We use ordinated Bray–Curtis distances based on 18 characters and 2D nonmetric multidimensional scaling to show that cuticular morphology resolves the three most diverse genera, Euroschinus, Mauria, and Schinus, but does not resolve intrageneric sections of Schinus. We propose that a distinctive acuminate gland type occurring only within Euroschinus may constitute a potential synapomorphy for this genus. Within Schinus, we find inconsistency in stomatal distribution among specimens of a single species, among species of a single section, and between sections of the genus, and suggest that current evidence is insufficient to implicate either phenotypic plasticity or homoplasy as the causative mechanism of this variation.

Functional redundancy in carrion decomposition by temperate forest ant communities

Abstract Scavenging of small avian corpses may provide ants with a valuable source of nutrients, a possibility poorly studied. Here, we assessed whether ants are efficient carrion‐decomposers of avian corpses in Mediterranean dehesas through an exclusion experiment comparing decomposition rates among three treatments: vertebrate exclusion, vertebrate + invertebrate exclusion and control. Treatments were applied in a paired design in bird cavities and on the ground in two zones to assess functional redundancy. Ant community was characterized by pitfall traps, and key functional traits influencing ants' presence on carrion were identified by using phylogenetic comparative methods. Carrion decomposition was influenced by the exclusion treatment, being significantly faster when ants and other invertebrates were not excluded, but not by location (cavity/ground). Vertebrates were less likely to detect baits in cavities and removed more bait mass in the most transformed zone. Twelve of 25 ant species in the community were found foraging on baits. Ant communities differed between carrion location and localities. Phylogenetic analyses revealed that the proneness of ant species to forage on carrion was unrelated to morphological or social traits, but behavioural, being higher among species foraging collectively. Our results show that ants play a functionally unique role in the decomposition of small corpses in dehesas, and particularly so in trees and less transformed pastureland. Decomposition involves different species in different microhabitats, suggesting high functional redundancy across ants. Our findings provide new insights into the role of ants as scavengers and expand our understanding of the functioning of Mediterranean communities.

Estructura y regeneración en un bosque de oyamel en una Área Natural Protegida al noroeste de México

Understanding forest structure and diversity allows the development and analysis of strategies for the sustainable management of natural resources. The objective of the research was to contribute to the knowledge of tree structure, as well as its regeneration capacity in an altitudinal gradient in a Natural Protected Area in Madera, Chihuahua. The study included three altitudinal intervals: lower (2 307 to 2 466 m), middle (2 466 to 2 625 m) and upper (2 625 - 2 785 m), in which 30 circular sites of 500 m2 were distributed where the diameter and height of the upper trees were measured, as well as the density of regeneration. The vertical structure was obtained with the Pretzsch index (A), in addition, the importance value index (IVI), diversity with the Shannon-Wiener index (H') and richness with Margalef (Dmg) were evaluated, as well as the renewal capacity and damage present. The values of A show the greatest structural homogeneity in interval 2; the Pinaceae family registered the highest ecological weight in the IVI; the values of H' and Dmg were higher in stratum II, however, all are considered of low diversity and richness; the species Abies concolor and Pseudotsuga menziesii, showed the highest proportion of regeneration in the community, in which suppression is the frequent damage, however, 95% of the individuals were not affected. This information is useful for the conservation of these ecologically important communities in temperate forests.

Different diversity patterns of butterfly and moth assemblages between deciduous and evergreen broad-leaf forests

In this study, we compared the diversity and abundance of two groups of Lepidopteran insects—butterflies and moths—across deciduous (DBL) and evergreen broad-leaved (EBL) tree communities in warm temperate forests. Over three years (from 2018 to 2020) at the Wando Arboretum, we used transect and point methods to sample butterflies and light traps to sample moths. Our findings revealed that the total estimated species richness was higher in EBL compared to DBL. Non-metric multidimensional scaling (NMDS) analysis confirmed distinct moth assemblages between the two tree communities, while butterfly assemblages did not exhibit such separation. The seasonal diversity patterns of butterflies in both forests differed significantly, whereas those of moths exhibited a similar trend with a peak in June. Beta diversity components indicated high turnover rates in moth assemblages across both tree communities and high nestedness in butterfly assemblages within the DBL. Although the diet breadth of butterflies and moths did not significantly differ between the two tree communities, the number of butterfly species per host plant was higher in DBL and that of moths was higher in EBL. Considering the ongoing vegetation transition from DBL to EBL, changes in forest structure—such as canopy openness and tree density—may adversely impact insect communities within DBL.

Impact of prescribed fire on soil microbial communities in a Southern Appalachian Forest clear-cut.

Escalating wildfire frequency and severity, exacerbated by shifting climate patterns, pose significant ecological and economic challenges. Prescribed burns, a common forest management tool, aim to mitigate wildfire risks and protect biodiversity. Nevertheless, understanding the impact of prescribed burns on soil and microbial communities in temperate mixed forests, considering temporal dynamics and slash fuel types, remains crucial. Our study, conducted at the University of Tennessee Forest Resources AgResearch and Education Center in Oak Ridge, TN, employed controlled burns across various treatments, and the findings indicate that low-intensity prescribed burns have none or minimal short-term effects on soil parameters but may alter soil nutrient concentrations, as evidenced by significant changes in porewater acetate, formate, and nitrate concentrations. These burns also induce shifts in microbial community structure and diversity, with Proteobacteria and Acidobacteria increasing significantly post-fire, possibly aiding soil recovery. In contrast, Verrucomicrobia showed a notable decrease over time, and other specific microbial taxa correlated with soil pH, porewater nitrate, ammonium, and phosphate concentrations. Our research contributes to understanding the intricate relationships between prescribed fire, soil dynamics, and microbial responses in temperate mixed forests in the Southern Appalachian Region, which is valuable for informed land management practices in the face of evolving environmental challenges.

Distinct communities under the snow: describing characteristics of subnivium arthropod communities.

Arthropods are active during the winter in temperate regions. Many use the seasonal snowpack as a buffer against harsh ambient conditions and are active in a refugium known as the subnivium. While the use of the subnivium by arthropods is well established, far less is known about subnivium community composition, abundance, biomass, and diversity and how these characteristics compare with the community in the summer. Understanding subnivium communities is especially important given the observed and anticipated changes in snowpack depth and duration due to the changing climate. We compared subnivium arthropod communities with those active during the summer using pitfall trapping in northern New Hampshire. We found that compositions of ground-active arthropod communities in the subnivium differed from those in the summer. The subnivium arthropod community featured moderate levels of richness and other measures of diversity that tended to be lower than the summer community. More strikingly, the subnivium community was much lower in overall abundance and biomass. Interestingly, some arthropods were dominant in the subnivium but either rare or absent in summer collections. These putative "subnivium specialists" included the spider Cicurina brevis (Emerton 1890) (Araneae: Hahniidae) and 3 rove beetles (Coleoptera: Staphylinidae): Arpedium cribratum Fauvel, 1878, Lesteva pallipes LeConte, 1863, and Porrhodites inflatus (Hatch, 1957). This study provides a detailed account of the subnivium arthropod community, establishes baseline information on arthropod communities in temperate forests of northeastern North America, and explores the idea of subnivium specialist taxa that are highly active in winter and might be especially vulnerable to climate change.

Tall, large-diameter trees and dense shrub layer as key determinants of the abundance and composition of bird communities in oak-dominated forests

Increasing human activity is altering the structure of forests, which affects the composition of communities, including birds. However, little is known about the key forest structure variables that determine the richness of bird communities in European temperate oak forests. We, therefore, aimed to identify key variables in these habitats that could contribute to the design of management strategies for forest conservation by surveying 11 oak-dominated forest sites throughout the mid-mountain range of Hungary at 86 survey points to reveal the role of different compositional and structural variables for forest stands that influence the breeding bird assemblages in the forests at the functional group and individual species levels. Based on decision tree modelling, our results showed that the density of trees larger than 30 cm DBH was an overall important variable, indicating that large-diameter trees were essential to provide diverse bird communities. The total abundance of birds, the foliage-gleaners, primary and secondary cavity nesters, residents, and five specific bird species were related to the density of high trunk diameter trees. The abundance of shrub nesters was negatively influenced by a high density of trees over 10 cm DBH. The density of the shrub layer positively affected total bird abundance and the abundance of foliage gleaners, secondary cavity nesters and residents. Analysis of the co-dominant tree species showed that the presence of linden, beech, and hornbeam was important in influencing the abundance of various bird species, e.g., Eurasian Treecreeper (Certhia familiaris), Marsh Tit (Poecile palustris) and Wood Warbler (Phylloscopus sibilatrix). Our results indicated that large trees, high tree diversity, and dense shrub layer were essential for forest bird communities and are critical targets for protection to maintain diverse and abundant bird communities in oak-dominated forest habitats.

Chronic enhanced nitrogen deposition and elevated precipitation jointly benefit soil microbial community in a temperate forest

Global change profoundly impacts carbon and nitrogen (N) cycling processes in terrestrial ecosystems by altering soil microbial communities. However, how enhanced N deposition and elevated precipitation jointly affect soil microbes and the underlying mechanisms remain poorly understood, particularly in forest ecosystems. In a long-term field experiment conducted in a temperate forest in China, we added N and/or water above the forest canopy to investigate their effects on soil microbial communities. Our results showed that N addition led to a decrease in bacterial biomass while increasing fungal biomass, resulting in an alteration of soil microbial community structure. Conversely, water addition did not significantly impact soil microbial communities. However, when N and water were added together, both fungal and bacterial biomass notably increased, leading to alterations in the soil microbial community structure. These results suggested that the effect of N addition could be mediated by elevated precipitation. Precipitation increment amplified the positive impact of N deposition on soil fungi but shifted its impact on bacteria from negative to positive. Additionally, soil bacteria were affected by soil N availability and acidification, as well as litter quality, whereas fungi were regulated by litter quantity and soil organic carbon. This study provides crucial evidence that concurrent enhanced N deposition and elevated precipitation favor soil microbial communities in temperate forests. It highlights the potential of elevated precipitation to alleviate the negative impacts of enhanced N deposition on temperate forest ecosystems, thereby sustaining ecological stability under global change scenarios.

Combining multiple investigative approaches to unravel functional responses to global change in the understorey of temperate forests

AbstractPlant communities are being exposed to changing environmental conditions all around the globe, leading to alterations in plant diversity, community composition, and ecosystem functioning. For herbaceous understorey communities in temperate forests, responses to global change are postulated to be complex, due to the presence of a tree layer that modulates understorey responses to external pressures such as climate change and changes in atmospheric nitrogen deposition rates. Multiple investigative approaches have been put forward as tools to detect, quantify and predict understorey responses to these global‐change drivers, including, among others, distributed resurvey studies and manipulative experiments. These investigative approaches are generally designed and reported upon in isolation, while integration across investigative approaches is rarely considered. In this study, we integrate three investigative approaches (two complementary resurvey approaches and one experimental approach) to investigate how climate warming and changes in nitrogen deposition affect the functional composition of the understorey and how functional responses in the understorey are modulated by canopy disturbance, that is, changes in overstorey canopy openness over time. Our resurvey data reveal that most changes in understorey functional characteristics represent responses to changes in canopy openness with shifts in macroclimate temperature and aerial nitrogen deposition playing secondary roles. Contrary to expectations, we found little evidence that these drivers interact. In addition, experimental findings deviated from the observational findings, suggesting that the forces driving understorey change at the regional scale differ from those driving change at the forest floor (i.e., the experimental treatments). Our study demonstrates that different approaches need to be integrated to acquire a full picture of how understorey communities respond to global change.

Quercus wutaishanica shrub affects temperate forest community composition and soil properties under different restoration stage.

Quercus wutaishanica is the dominant tree species in the natural ecosystem restoration of temperate forests in China, and it plays an active role in maintaining ecological balance. However, little is known about how ecosystem versatility develops during the restoration of forest ecosystems dominated by Q. wutaishanica. In this study, we investigated the species composition of the Q. wutaishanica community, soil nutrients, and their functional traits at various restoration stages, and comprehensively analyzed the correlations among them. At the early stage of restoration (10 years of restoration), there were Spiraea pubescens and Syringa pubescens in Q. wutaishanica community (87% of the total species), while had a larger niche width. In the middle of restoration (30 years of restoration), shannon and evenness indices were the largest, while soil total carbon, ammonium nitrogen and chlorophyll content of Q. wutaishanica leaves were the highest; among them, soil total carbon was 15.7% higher than that in 10 years of restoration, 32.4% higher than that in 40 years of restoration, ammonium nitrogen was 71.7% higher than that in 40 years of restoration, and chlorophyll content was 217.9% higher than that in 10 years of restoration, and 51.8% higher than that in 40 years of restoration. At the later stage of restoration (40 years of restoration), Lonicera ferdinandii occupied the dominant ecological niche, and soil available nitrogen, available phosphorus content and leaf thickness were the largest; while AN was 10.9% higher than that of 10 years of restoration, 16.5% higher than that of 30 years of restoration, AP was 60.6% higher than that of 10 years of restoration, 21.6% higher than that of 30 years of restoration, leaf thickness was 22.3% higher than that of 10 years of restoration, 84.9% higher than that of 30 years of restoration. However, the restriction of various soil nutrients was reduced. Our study highlighted the effectiveness of soil resource availability in plant communities during restoration, reduced competition for light among plants, and altered species richness. Furthermore, changes in the interrelationship between plant community composition and leaf functional traits of the dominant species responded positively to community restoration. These results further deepen our understanding of forest management and restoration of forest communities. In the future, it is necessary to comprehensively consider the influence of various factors on forest community restoration.

Temperate tree microbiomes: divergent soil and phyllosphere microbial communities share few but dominant taxa

AimsThe phyllosphere and soil are crucial and distinct microbial spheres in forests, connected through trees that interact with both. As part of the tree's holobiont, these communities are vital to the fitness and evolution of the host. Differences between the spheres may be particularly evident at the two extreme ends of tall and long-lived trees of natural temperate forest; the top-canopy and the soil. Here, we evaluated the connectivity between the top-canopy and soil microbial communities of European beech and Norway spruce trees to determine the significance of tree-sphere and host-species identity, and to assess the contribution of taxa inhabiting both spheres.MethodsBacterial and fungal community composition was determined through metabarcoding analysis of linked top-canopy leaf and bulk soil samples collected from tall (old) trees in the natural forest of Bavarian Forest National Park.ResultsThis study shows sphere-specific communities in European temperate forests, characterized by low connectivity. Results highlight that spheres exert stronger influence than host identity. Only a few taxa inhabited both spheres, yet they accounted for the bulk of the (relative) abundance in each sphere.ConclusionAnalysing the divergence and shared characteristics of these interlinked communities redefines the tree holobiont concept and enhances our understanding of the evolution of plant-associated microbial communities in a sphere-specific manner. This study emphasizes the importance of examining multiple microbiome components for a thorough understanding of temperate forest ecology, while also highlighting the existence of a small group of overlapping taxa that may play a bigger role than previously anticipated.

Elevational changes in canopy Collembola community composition are primarily driven by species turnover on Changbai Mountain, northeastern China

Forest canopies harbor extraordinary biodiversity, with Collembola being one of the most abundant arthropod taxa. However, much of the research on canopy biodiversity has focused on tropical and subtropical regions, leaving a gap in our understanding of canopy communities in temperate and boreal forests. Studying canopy Collembola along elevational gradients can be particularly informative because several environmental factors change with elevation, and these changes may mirror those seen along latitudinal gradients. To better understand and conserve canopy Collembola diversity along elevational gradients, natural forests are of particular interest. In this study, we used canopy fogging to sample canopy Collembola at four elevation sites (800–1700 m a.s.l.) on Changbai Mountain, northeastern China, representing three natural forest types. We examined changes in species richness, abundance and composition of canopy Collembola, and partitioned beta diversity into nestedness and turnover to identify processes driving changes in community composition. We identified 53 morphospecies among 10,191 individuals, with Entomobryidae and Hypogastruridae being the dominant families. The highest abundance and species richness were observed at 1400 m and remained at similar levels at 1700 m, indicating an increasing pattern with elevation. Species turnover was the main driver of changes in community composition with elevation. Our results provide insights into the shift of canopy Collembola communities across an elevational gradient in temperate boreal forests.

Tropical and temperate differences in the trophic structure and aquatic prey use of riparian predators.

The influence of aquatic resource-inputs on terrestrial communities is poorly understood, particularly in the tropics. We used stable isotope analysis of carbon and nitrogen to trace aquatic prey use and quantify the impact on trophic structure in 240 riparian arthropod communities in tropical and temperate forests. Riparian predators consumed more aquatic prey and were more trophically diverse in the tropics than temperate regions, indicating tropical riparian communities are both more reliant on and impacted by aquatic resources than temperate communities. This suggests they are more vulnerable to disruption of aquatic-terrestrial linkages. Although aquatic resource use declined strongly with distance from water, we observed no correlated change in trophic structure, suggesting trophic flexibility to changing resource availability within riparian predator communities in both tropical and temperate regions. Our findings highlight the importance of aquatic resources for riparian communities, especially in the tropics, but suggest distance from water is less important than resource diversity in maintaining terrestrial trophic structure.

Variation and drivers of soil fungal and functional groups among different forest types in warm temperate secondary forests

Soil fungal communities play a crucial role in maintaining and regulating ecosystem functions. The soil fungal structure of different plant communities in forests has been widely studied. However, the drivers of changes in soil fungal community dynamics in warm temperate secondary forests and the pathways influencing them remain to be explored. The Illumina high-throughput sequencing and FUNGuild platform were used to characterize the soil fungal diversity and community composition of six typical plant communities (JM, Juglans mandshurica; PD, Populus davidiana; QM, Quercus mongolica; MB, mixed broadleaf forest; MC, mixed conifer forest; PT, Pinus tabuliformis) in warm temperate secondary forests. The drivers of structural changes in dominant fungal taxa and functional groups were also explored. The pathways through which forest type, soil properties, altitude, climate, and plant diversity affected fungal community structure were further clarified. The results suggested that Ascomycota, Basidiomycota, and Zygomycota dominated the soil fungal communities in warm temperate secondary forests. Except for symbiotic fungi, there was no significant difference in soil fungal α-diversity among forest types. However, there were significant differences in total fungi and functional group community composition. The drivers of diversity and community composition of different soil fungal taxa in warm temperate secondary forests differed. In addition, the partial least squares path model indicated that the composition of soil fungal community in warm temperate secondary forests was directly influenced by forest type and was less dependent on soil properties. Collectively, our study highlights the importance of forest type, soil properties, and other factors (climate, altitude, plant diversity) in driving changes in soil fungal community structure.

Alteration of a temperate forest invertebrate community by invasive Japanese barberry (Berberis thunbergii) has limited influence on the diet composition of territorial ovenbirds (Seiurus aurocapilla)

Invasive species are widely implicated in the decline of songbird populations, potentially via indirect effects such as the restructuring of ecological communities by non-native plants. We used stable isotope analysis to investigate whether ground-foraging, generalist insectivore ovenbirds ( Seiurus aurocapilla (Linnaeus, 1766)) shifted diets following invasion by a non-native shrub, Japanese barberry ( Berberis thunbergii DC.), in a temperate woodland system in New York, USA where barberry was previously linked to trophic downgrading in the leaf litter arthropod community. Assimilated ovenbird diets were primarily composed of predatory invertebrates followed by sucking herbivores, chewing herbivores, and detritivores. The only notable changes in assimilated ovenbird diets were a modest 14.7% decrease in chewing herbivore contributions and a minor 7.0% increase in sucking herbivore contributions in forest patches with high barberry densities. Our results indicate that the effects of non-native plants on connections between higher trophic levels are context-dependent, and comparisons with other studies suggest that community complexity and time since introduction are key contextual differences that affect the outcome of an invasion. Our results may reflect compensatory shifts in individual foraging effort by ovenbirds, but, in combination with our previous research, provide little evidence that barberry affects ovenbird condition and therefore downstream outcomes.

Investigating the effects of tree species diversity and relative density on bird species richness with acoustic indices

Mixed-species forest stands may provide suitable habitats for more bird species than tree monocultures by increasing the number of niches and resources available. However, assessing the effects of forest diversity on birds over time and across multiple sites using traditional bird survey methods can be expensive, time-consuming and impractical. Alternatively, we used passive acoustic monitoring (PAM) and acoustic indices to investigate how tree species diversity, relative density, and other plot characteristics affect the species richness of avian communities in temperate forests. Acoustic monitoring was conducted in Nationalpark Hainich, Germany, using plots which differed in tree species diversity and relative species density. Using a subset of our data, five acoustic indices, the normalised difference soundscape index (NDSI), acoustic complexity index (ACI), bioacoustic index (BI), the acoustic evenness index (AEI) and temporal entropy (Ht), were initially assessed using audio recordings of different soundscape elements to determine the degree to which they were influenced by non-biophony soundscape elements. Of these, NDSI, ACI and BI were considered least biased and displayed significant positive relationships with bird species richness assessed using audio recordings. However, NDSI values plateaued at around 5 bird species when measuring bird species richness and ACI values for dawn choruses were lower than expected, potentially due to the high density of birdsong saturating the soundscape. Plot tree species diversity had significant positive effects on ACI and BI during dawn, dusk and daytime periods. Increased basal area of sycamore (Acer pseudoplatanus) and, to a lesser degree, beech (Fagus sylvatica), had a negative effect on acoustic indices. These results could potentially be due to the earlier leaf out timings of these tree species in relation to the dates when surveys were performed. While the use of PAM and acoustic indices enabled surveys across multiple sites over longer time periods than would previously have been achievable, our results show that care should be taken when selecting indices and interpreting acoustic index results.

Temperate forest understory vegetation shifts after 40 years of conservation

Understanding how vegetation composition and diversity respond to global changes is crucial for effective ecosystem management and conservation. This study evaluated shifts in understory vegetation after 40 years of conservation within Drawa National Park (NW Poland), to check which plant communities changed the most, and whether vegetation shifts reflect global change symptoms (climate change and pollution) or natural forest dynamics. Using ordination and generalized mixed-effects linear models, we assessed changes in alpha diversity metrics, accounting for taxonomic, functional, and phylogenetic aspects within 170 quasi-permanent plots, surveyed in 1973–85 and resurveyed in 2015–19. We found an overall homogenization of forest vegetation and specific shift patterns in certain forest associations. In coniferous and nutrient-poor broadleaved forests, the overall number of species increased due to the replacement of functionally distinct or specialized species with more ubiquitous species that could exploit increased resource availability. In riparian forests and alder carrs we found either shifts from riparian forest to alder carrs or to mesic broadleaved forests. The most stable communities were fertile broadleaved forests. Our study quantified shifts in taxonomic, functional, and phylogenetic diversity after 40 years of conservation and provides important insights into the shifts in vegetation composition in temperate forest communities. In coniferous and nutrient-poor broadleaved forests we found an increase in species richness and replacement of functionally distinct or specialized species by ubiquitous species, indicating increased resource availability. Shifts between wet broadleaved forests and transition into mesic forests suggest water limitation, which can be related to climate change. The most stable were fertile broadleaved forests fluctuating due to natural stand dynamics. The findings highlight the need for ongoing monitoring and management of ecological systems to preserve their diversity and functionality in the face of global changes.

Forest Tent Caterpillar Outbreaks Drive Change in Ant Communities in Boreal Forests

Insect outbreaks are major drivers of natural disturbances in forest ecosystems. Outbreaks can have both direct and indirect effects on the composition of soil arthropod communities through canopy opening, nutrient addition and predator-prey interactions. In this study, we aimed to understand the effects of forest tent caterpillar (Malacosoma disstria; FTC) outbreaks through cascading effects on ant communities in both temperate and boreal forests in Canada. Pitfall traps and Berlese funnels were used to compare the ant communities, as well as the surrounding arthropod communities, between control and outbreak sites in boreal and temperate forests (in Quebec, Canada). Using the Sørensen dissimilarity index, we determined the alpha and beta diversity of the ant community. Other arthropods collected in the traps were counted to evaluate the richness and abundance of potential prey for the ants and other potential predators of the FTC. We used an indicator species analysis to examine the species associated with sites defoliated by the outbreak. In the boreal forest, we found that FTC outbreaks caused decreases in species richness and increases in the evenness of ant communities in defoliated sites. In the boreal forest sites, species composition varied significantly between control and outbreak sites. This pattern was driven in part by the presence of other predators. A similar, but weaker pattern was observed in the temperate forest. We saw no changes in the beta diversity in the boreal forest, but did see a significant decrease in the temperate forest between the outbreak sites and the control sites. Ant species in the boreal forest tended to exhibit a more marked preference for either control or previously defoliated sites than species in the temperate forest. Our study showed that disturbances such as insect outbreaks can drive changes in the ant community. While we saw small effects of outbreaks, manipulation experiments using resource addition could help us validate the mechanisms behind these relationships.