Diversity Of Forest Communities Research Articles

Insect seedling herbivory is influenced by multiple factors, but the plant apparency theory is more supported than other hypotheses – A case study in a subtropical forest

Insect herbivory is ubiquitous in various ecosystems, and directly influences the growth and survival of individual plants, especially during their vulnerable early life stages like the seedling phase. This, in turn, exerts a significant influence on forest community diversity and structure, as well as ecosystem function and stability. Notable variation in herbivory has been detected both among and within plant species. For decades, many hypotheses have been proposed to explain such variations, including both biotic and abiotic variables. However, most studies have considered only one or several of these hypotheses by focusing on a few potential variables, and their results were usually inconsistent; thus, the factors driving herbivory remain unclear. In this study, we examined leaf herbivory by insects of woody species seedlings in a subtropical forest in southwestern China over two seasons. In total, 24 potential variables that represented abiotic resource availability, characters of individual seedlings, conspecific and heterospecific species, and the whole seedling community were selected to test several commonly discussed alternative herbivory hypotheses. Overall, our findings showed that the plant apparency hypothesis was more supported than the other hypotheses in explaining insect seedling herbivory. Our results further indicated that the mechanisms and causes of insect herbivory are complex, multifactorial, species-specific and vary with seasons, indicating that there may be no uniform rules in explaining herbivory for all seedlings. Consequently, such complexity may play an important role in promoting species coexistence and biodiversity maintenance in seedling communities, which may further translate into the following generation of saplings or even adult communities. Changes in the community of insect herbivores and/or variables influencing insect herbivory, may disrupt stability of the original seedling community, thus affecting the regeneration and development of the entire forest community. Therefore, we suggest that issues related to insect herbivory should be considered when developing forest management and conservation.

Effect of species-independent conspecific and heterospecific density dependence is contingent on seedling growth stage, season, and climate conditions

Conspecific negative density dependence (CNDD) and its extension heterospecific positive density dependence (HPDD) are the two most prominent mechanisms used to explain the maintenance of species diversity in forest communities. However, the impact of species identity, growth stage, seasonal and inter-annual variation in precipitation and temperature on conspecific and heterospecific density dependence remains poorly understood. Based on a decade of seedling (dbh < 1 cm) and tree (dbh ≥ 1 cm) census data from a 5-ha subtropical evergreen broad-leaved forest in eastern China, we used generalized linear mixed models with crossed random effects to test whether seedling survival was density dependent and varied by growth stage, species identity, season or interacted with inter-annual variation in seasonal precipitation and temperature. In addition to conspecific and heterospecific seedling and tree density, the height (or age) of the seedlings, habitat variables, seasonal precipitation and temperature and the interactions between conspecific and heterospecific seedling and tree density and seasonal precipitation and temperature were also used as predictors. The results of our long-term, spatially, and temporally explicit study showed that the strength of CNDD and enemy induced HPDD was stronger in summer and at early seedling stages, whereas interspecific facilitation induced HPDD mainly in winter for early and late seedling stages. Additionally, the effects of seasonal temperature and precipitation, and the soil PC1 axis (which correlated positively with soil nutrients and negatively with soil moisture) on seedling survival varied with season, seedling stage, and focal species identity, indicating the potential for niche partitioning among species in this community. However, neither conspecific nor heterospecific neighbor effects varied among focal seedling species, which resulted in a community compensatory trend in young seedlings. Variation in the effect of CNDD and HPDD across seedling stages, seasons, and inter-annual fluctuations of climate conditions highlights the necessity of long-term monitoring of the dynamics of CNDD in tree communities.

Changes in the Number of Vascular Plant Species during Reforestation of Clearcut Forests

The article aims to describe the patterns of changes in the number of vascular plant species in communities at different stages of forest regeneration after clearcutting using the space-for-time substitution method. Large-scale logging in boreal forests leads to a simplification of the territory’s forest cover (the formation of even-aged stands), which in turn leads to a decrease in the diversity of forest communities and species diversity. These tendencies have been confirmed for many groups of organisms, especially those associated with old trees and dead wood; however, this is not so clear for vascular plants. We investigated plant communities at different stages of regeneration. We used the so-called space-for-time substitution (chronosequence) method of building dynamic series for four forest ecotopes, where industrial clearcuts are most actively carried out. We showed that the fertility of forest ecotopes determines the species pool—the richer the conditions, the more species that can potentially inhabit the community. At the same time, the structure of the tree stand significantly affects the composition and number of species in the community. The lowest species richness was in old-growth forests characterized by the dominance of one species in the tree stand and one or two vascular plant species in the ground cover. With insignificant fluctuations in the average number of species between stages of forest regeneration after logging, some communities at clearcuts in bilberry (Vaccinium myrtillus L.) pine (Pinus sylvestris L.) and spruce (Picea abies (L.) H.Karst.) forests have high species diversity due to the occupation of the site by species of open habitats. These clearcuts are located not far from settlements and close to roads.

Community vertical stratification drives temporal taxonomic and phylogenetic beta diversity in a mixed broadleaf-conifer forest

Temporal change of beta diversity provides a better understanding of the extent and consequences of species composition in forest communities with the ongoing global climate change. However, relatively little is known about temporal beta diversity changes across vertical stratification in the forest. In this study, we divided more than 5,000 tree individuals from a mixed broadleaf-conifer forest into four vertical strata (i.e., shrub, subcanopy, lower canopy, and upper canopy) to quantify how vertical stratification drives the temporal change of taxonomic and phylogenetic beta diversity. We found that taxonomic beta diversity significantly decreased while phylogenetic beta diversity showed an insignificant increase after 5 years. When considering vertical stratification, taxonomic beta diversity in the subcanopy, lower canopy, and upper canopy significantly changed with inconsistent directions, but phylogenetic beta diversity in the shrub significantly increased. Moreover, the significant decrease in taxonomic beta diversity is mainly driven by changes in species composition in shrub and subcanopy stratification (with 85.89% contributions). The changes in phylogenetic beta diversity are driven by shifts in the shrub and upper canopy (with 96.02% contributions). Our study suggests that taking community vertical stratification into consideration contributes to a better understanding of temporal beta diversity in forest communities.

Overlapping outbreaks of multiple bark beetle species are rarely more severe than single‐species outbreaks

AbstractBiotic disturbances that overlap in space and time may result in important shifts in forest structure and composition, with potential effects on many ecosystem services. Starting in the late 1990s, outbreaks of multiple bark beetle species caused widespread mortality of three co‐occurring conifer species in the ca. 40,000‐km2 subalpine zone of the southern Rocky Mountains (SRM), USA. To better understand the implications of such outbreaks, our goal was to determine if overlapping outbreaks of multiple bark beetle species caused greater tree mortality than single‐species outbreaks in stands with multiple susceptible host tree species. We mapped stand susceptibility to outbreaks of spruce beetle (SB, Dendroctonus rufipennis), mountain pine beetle (MPB, Dendroctonus ponderosae), and western balsam bark beetle (WBBB, Dryocoetes confusus) by combining aerial survey data and forest composition variables in a random forest modeling framework. Then, we used existing maps of cumulative forest mortality from bark beetles to investigate the extent and severity of overlapping outbreaks from 1999 to 2019. We found that 46% of stands with two or more of the three studied hosts species—Engelmann spruce (Picea engelmannii), lodgepole pine (Pinus contorta var. latifolia), or subalpine fir (Abies lasiocarpa)—were susceptible to overlapping outbreaks (25% of all sampled stands). Of those stands, 31% experienced outbreaks of two or more beetle species. Stands affected by outbreaks of both MPB and SB had higher tree mortality than stands affected by one species alone, though stands susceptible to both MPB and SB were uncommon (&lt;4% of all sampled stands). No other combinations of beetle outbreaks increased tree mortality above levels caused by single‐species outbreaks. Thus, contrary to expectations, overlapping outbreaks were rarely more severe than single‐species outbreaks in the SRM. This suggests that diverse forest communities may buffer against the most severe effects of bark beetle outbreaks, even during warm, dry conditions.

Changes in woody species beta diversity in forest communities reveal conservation priorities in the southeastern Qinghai-Tibet Plateau

Changes in woody species beta diversity in forest communities reveal conservation priorities in the southeastern Qinghai-Tibet Plateau

Fine-scale topographic influence on the spatial distribution of tree species diameter in old-growth beech (Fagus orientalis Lipsky.) forests, northern Iran

The Hyrcanian forest in northern Iran is threatened by human use and encroachment and has suffered degradation in some areas. The forest has been declared a World Heritage Site and management in the region is shifting from timber production to conservation. There is considerable interest in developing a greater understanding of these diverse forest communities to inform forest management and multiple use plans to maintain the diversity and resilience of these forests. The Hyrcanian forest is characterized by a complex topography of catenas ranging up mountain slopes. Topographic gradients greatly influence microhabitat conditions which in turn impact tree distribution. To date there has been limited research on the impacts of this diverse topography on the spatial distribution of tree species and tree diameters in Hyrcanian forests. Such information is necessary to better understand the regional traits of tree diameters in these natural mixed temperate forests before forest management occurs. We examined the influence of the area’s catena topography on the spatial pattern of tree species and on species stand structure in terms of tree diameter distribution. To quantify these dynamics, we conducted a complete enumeration inventory of all trees with dbh >12 cm within a 7.947 ha study area that included three C-shaped (concave) and three V-shaped (convex) catenas. Geostatistical variogram analysis and Clark and Evans aggregation index were utilized to study the spatial distribution of tree diameters. Beech, alder, hornbeam, linden and Persian maple exhibited clustered patterns, and sour cherry, ash, and oak exhibited random patterns. Geostatistical analysis clearly revealed the substantial influence of catena topography on the diameter distributions of alder and linden, more subtle influence on the diameter distributions of beech, and a possible influence on Persian maple, providing valuable insight into stand structure over neighborhood-based indices alone. Alder and linden both exhibited strong spatial structure in their diameter distributions (56% and 86%, respectively) where their diameter was strongly correlated with trees within 108 m and 83 m, respectively, sharing more similar diameters to each other than trees beyond that distance. Beech, maple, and hornbeam exhibited very weak if any spatial structure over short distances. These findings can be used to support the alignment of forest management practices in managed Hyrcanian forests with goals of protecting and maintaining biodiversity and sustainable forest ecosystems, and to inform geospatial modeling of species diameter distributions in areas where a complete stem-map is not feasible.

Spectral index-based time series analysis of canopy resistance and resilience in a watershed under intermittent weather changes

Understanding the long-term impact of intermittent weather events on diverse forest and plant communities at the canopy level has become a key issue in sustainability science. Unlike a single event, intermittent weather events may exert more physiological and biological pressure on terrestrial vegetative surfaces. The amalgamation of spectral index-based satellite remote sensing information to assess intermittent weather changes in canopy dynamics may help identify phenological shifts of biota in response to external and consecutive disturbances. We conducted this study to assess such impacts of alternating weather changes on grassland, agricultural, deciduous forested, and evergreen forested land uses via remote sensing and to compare the resilience and resistance of canopy under intermittent weather changes in a subtropical watershed. The research findings indicate that deciduous forested and evergreen forested land showed a strong correlation between canopy-level biophysical and biochemical properties driven by land surface temperature. The variation of energy driven by land surface temperature changes the sensitivity levels of resilience in forest land uses, affecting the gross primary productivity.

Correcting the Results of CHM-Based Individual Tree Detection Algorithms to Improve Their Accuracy and Reliability

Individual tree detection algorithms (ITD) are used to obtain accurate information about trees. Following the process of individual tree detection, it is possible to use additional processing tools to determine tree parameters such as tree height, crown base height, crown volume, or stem volume. However, many of the methods developed so far have focused on parameterising the algorithms based on the study area, height structure or tree species analysed. Applying the parameters of the method can be challenging in areas with dense and heterogeneous forests with a diverse stand structure. Therefore, this work aimed to develop a method to correct the results of ITD algorithms to identify individual trees more reliably, taking into account different ITD methods based on the Canopy Height Model. In the present study, we proposed a three-step approach to correct segmentation errors. In the first step, erroneous (under- and over-segmentation errors) and correct segments were classified. After classification, the second step was to refine the under-segmentation errors. The final step was to merge segments from the over-segmentation class with correct segments based on the specified conditions. The study was conducted in one of the most complex and diverse forest communities in Europe, making tree identification a major challenge. The accuracy of the segmentation improvements varied depending on the method applied and tree species group examined. Thus, based on the results, the paper advocates for the correction method due to its efficiency in mixed forest stands. Therefore, the present study offers a possible solution to reduce segmentation errors by considering different forest types and different CHM-based ITD methods for identifying individual trees.

Distinct Community-Wide Responses to Forecasted Climate Change in Afrotropical Forests

More refined knowledge of how tropical forests respond to changes in the abiotic environment is necessary to mitigate climate change, maintain biodiversity, and preserve ecosystem services. To evaluate the unique response of diverse Afrotropical forest communities to disturbances in the abiotic environment, we employ country-wide tree species inventories, remotely sensed climate data, and future climate predictions collected from 104 1-ha plots in the central African country of Gabon. We predict a 3–8% decrease in Afrotropical forest species richness by the end of the century, in contrast to the 30–50% loss of plant diversity predicted to occur with equivalent warming in the Neotropics. This work reveals that forecasts of community species composition are not generalizable across regions, and more representative studies are needed in understudied diverse biomes. This study serves as an important counterpoint to work done in the Neotropics by providing contrasting predictions for Afrotropical forests with substantially different ecological, evolutionary, and anthropogenic histories.

Effects of microtopography on soil fungal community diversity, composition, and assembly in a subtropical monsoon evergreen broadleaf forest of Southwest China

Topography is a critical factor that determines the patterns and assemblages of species diversity in forest communities. Small-scale topography changes are defined as microtopography. Our understanding of the effects of microtopography on soil fungal communities is limited. The objective of this study was to explore the impact of microtopography on soil fungal community diversity, community composition, functional guild, and community assembly. The diversity, composition, and relative abundance of functional guilds were measured using Illumina high-throughput sequencing techniques in five microtopography types (steep slope, less-steep slope, valley, high plateau, and ridge). OTU and Chao1 indexes were the highest in the high plateau and were the lowest in the ridge. The Shannon index was the lowest in the valley, and the highest in the ridge. In the valley, soil fungal networks were more interconnected than they were in any of the other microtopography unit. At the class level, the relative abundance of Agaricomycetes, Eurotionmycetes, and Leotiomycetes were higher in the ridge unit. The relative abundance of ectomycorrhiza, the dominant functional guild, in the ecosystem was as follows: less-steep slope (71.31%), ridge (66.55%), valley (65.83%), steep slope (63.91%), and high plateau (60.09%). Microtopography influenced fungal community diversity and composition more than any other factor and had, varying degrees of influence on the different functional guilds. In every microtopography type, dispersal limitations and drift shaped fungal communities more than other ecological processes. Our findings suggest that microtopography affects soil fungal community diversity and composition, functional guilds, and the relative contributions of ecological processes to soil fungal communities in subtropical monsoon evergreen broadleaf forests.

Предварительные итоги изучения флоры Нерчуганского заказника (Забайкальский Край)

The purpose of this work is to study the species composition and analysis of the flora of the «Nerchugansky» reserve. The Nerchugansky State Nature Reserve of regional significance was created in the Tungokochensky District of Zabaikalsky Krai, part of the Far Eastern Federal District, with the support of WWF Russia to preserve its natural heritage. This large protected area is situated in the basin of the Amur River – in the valley of the Nercha River and its most important tributary, the Nerchugan. The importance of this PA in terms of environmental safety is explained by the fact that several large placer gold mines operate in the region, which has a signifi cant negative impact on natural systems. The article presents the data of field studies of the terrestrial ecosystem of the reserve. As a result of the collected material, a systematic register of plant flora has been compiled with the allocation of leading families. The results of the chorological analysis are presented and the features of the formation of vegetation cover in this territory are revealed. The zonal and ecological classifications of the vegetation cover are distributed. The phytosozological analysis of the flora of the reserve was carried out. A number of rare and needy plant species have been identifi ed. The analysis of the flora of the first stage of the study showed the presence of 167 species from 112 genera belonging to 40 families, with the selection of the leading ones. Of these, 10 species belonging to 9 genera from 6 families are included in the Red Book of the Zabaikalsky (Trans-Baikal) Krai. This area is characterized by a diversity of forest communities as well as isolated relict areas of mountain steppes with high species diversity. Preservation of intact natural communities and development of mechanisms of sustainable nature management will preserve biodiversity and ecosystem services of the territory.

Spatial associations between plants and vegetation community characteristics provide insights into the processes influencing plant rarity.

Determining the drivers of plant rarity is a major challenge in ecology. Analysing spatial associations between different plant species can provide an exploratory avenue for understanding the ecological drivers of plant rarity. Here, we examined the different types of spatial associations between rare and common plants to determine if they influence the occurrence patterns of rare species. We completed vegetation surveys at 86 sites in woodland, forest, and heath communities in south-east Australia. We also examined two different rarity measures to quantify how categorisation criteria affected our results. Rare species were more likely to have positive associations with both rare and common species across all three vegetation communities. However, common species had positive or negative associations with rare and other common species, depending on the vegetation community in which they occurred. Rare species were positively associated with species diversity in forest communities. In woodland communities, rare species were associated negatively with species diversity but positively associated with species evenness. Rare species with high habitat specificity were more clustered spatially than expected by chance. Efforts to understand the drivers of plant rarity should use rarity definitions that consider habitat specificity. Our findings suggest that examining spatial associations between plants can help understand the drivers of plant rarity.

Longhorned Beetle Functional Diversity in Response to Biomass Harvesting.

Woody debris left after timber harvest may be used to produce bioenergy. This will help reduce reliance on nonrenewable fossil fuels. There are ecological impacts to the use of this woody material as many species use coarse woody debris for food and shelter. An understanding of how the removal of woody biomass after forest harvest changes the functional diversity of forest communities is needed to make sustainable management decisions. Many longhorned beetles (Coleoptera: Cerambycidae) provide ecosystem services by reducing woody debris in forests and pollinating flowering plants including trees. I used a taxonomically and functionally diverse community of longhorned beetles to examine changes to functional diversity following different levels of biomass removal in a secondary forest in south-central Indiana, USA. The functional diversity was measured prior to forest harvest and biomass removal and for 2 yr after treatment. I predicted that the abundance and functional group richness of the longhorned beetles would correlate positively with the volume of woody biomass left on the site, and that the community would show resilience by returning to the functional portfolio that was in place in the pre-harvest communities and occurred in the control. The abundance and functional group richness increased with more woody debris left on site. There was much variance in the trajectory of the community following harvest, with no clear trend toward pre-harvest functional portfolio that would indicate resilience. A 3-yr study is likely not long enough to capture this resilience, especially on sensitive sites.

Species diversity of typical forest communities in Taizhou Green Heart zone

Taking six typical forest communities in Taizhou Green Heart (ⅰ: Liquidambar formosana + Ulmus pumila + Celtis sinensis; ⅱ: Celtis sinensis + Pterocarya stenoptera + Pinus massoniana; ⅲ: Sapindus mukorossi + Sapium sebiferum + Cupressus funebris; ⅳ: Liquidambar formosana + Acer buergerianum + Cupressus funebris); ⅴ: Celtis sinensis + Ligustrum compactum + Pinus massoniana; ⅵ: Machilus ichangensis + Sapindus mukorossi + Acer buergerianum) as the research objects, 5 indicators: Shannon-Wiener (H), Patrick richness (R1), Margalef species richness (R2), Pielou evenness (J) and ecological dominance (D) were used to analyze species diversity in forest communities. The results showed that: (1) the community was rich in plant resources, with a total of 50 species belonging to 40 genus and 31 families, including 19 species in tree layer, 22 species in shrub layer and only 9 species in herb layer, few plant species; (2) the species richness and diversity index of tree layer and shrub layer were significantly higher than that of herb layer, but there were differences among different communities in the same layer, and no significant difference was reached; (3) the species richness and community diversity of the six communities showed as follows: community VI &gt; community I &gt; community II &gt; community IV &gt; community V &gt; community III.

Topographic Effects on the Spatial Species Associations in Diverse Heterogeneous Tropical Evergreen Forests

Studying spatial patterns and habitat association of plant communities may provide understanding of the ecological mechanisms and processes that maintain species coexistence. To conduct assessments of correlation between community compositions and habitat association, we used data from two topographically different plots with 2 ha area in tropical evergreen forests with the variables recorded via grid systems of 10 × 10 m subplots in Northern-Central Vietnam. First, we tested the relationship between community composition and species diversity indices considering the topographical variables. We then assessed the interspecific interactions of 20 dominant plant species using the nearest-neighbor distribution function, Dij(r), and Ripley’s K-function, Kij(r). Based on the significant spatial association of species pairs, indices of interspecific interaction were calculated by the quantitative amounts of the summary statistics. The results showed that (i) community compositions were significantly influenced by the topographic variables and (ii) almost 50% significant pairs of species interactions were increased with increasing spatial scales up to 10–15 m, then declined and disappeared at scales of 30–40 m. Segregation and partial overlap were the dominant association types and disappeared at larger spatial scales. Spatial segregation, mixing, and partial overlap revealed the important species interactions in maintaining species coexistence under habitat heterogeneity in diverse forest communities.

Trade‐offs in above‐ and below‐ground biomass allocation influencing seedling growth in a tropical forest

Abstract Plants allocate biomass to different organs in response to resource variation for maximizing performance, yet we lack a framework that adequately integrates plant responses to the simultaneous variation in above‐ and below‐ground resources. Although traditionally, the optimal partition theory (OPT) has explained patterns of biomass allocation in response to a single limiting resource, it is well‐known that in natural communities multiple resources limit growth. We study trade‐offs involved in plant biomass allocation patterns and their effects on plant growth under variable below‐ and above‐ground resources—light, soil N and P—for seedling communities. We collected information on leaf, stem and root mass fractions for more than 1,900 seedlings of 97 species paired with growth data and local‐scale variation in abiotic resources from a tropical forest in China. We identified two trade‐off axes that define the mass allocation strategies for seedlings—allocation to photosynthetic versus non‐photosynthetic tissues and allocation to roots over stems—that responded to the variation in soil P and N and light. Yet, the allocation patterns did not always follow predictions of OPT in which plants should allocate biomass to the organ that acquires the most limiting resource. Limited soil N resulted in high allocation to leaves at the expense of non‐photosynthetic tissues, while the opposite trend was found in response to limited soil P. Also, co‐limitation in above‐ and below‐ground resources (light and soil P) led to mass allocation to stems at the expense of roots. Finally, we found that growth increased under high‐light availability and soil P for seedlings that invested more in photosynthetic over non‐photosynthetic tissues or/and that allocated mass to roots at the expense of stem. Synthesis. Biomass allocation patterns to above‐ and below‐ground tissues are described by two independent trade‐offs that allow plants to have divergent allocation strategies (e.g. high root allocation at the expense of stem or high leaf allocation at the expense of allocation to non‐photosynthetic tissues) and enhance growth under different limiting resources. Identifying the trade‐offs driving biomass allocation is important to disentangle plant responses to the simultaneous variation in resources in diverse forest communities.

Beyond neutrality: adding habitat filtering to neutral models

BackgroundUnderstanding the processes that structure species is one of the primary focuses in community ecology. Hubbell’s neutral model shows stochastic processes alone can describe the two macro-ecological patterns, species richness and species-area relationship, of the community. Although Hubbell’s neutral model can explain the macro-ecological patterns of the species at large scales, it paid less attention to construct the spatial structure of the community. Previous studies suggest that such spatial structures are mostly due to habitat filtering processes work at the intermediate spatial scales. Therefore, Hubbell’s neutral model does not explain the full picture of the community structuring due to its fully stochastic nature.ResultsIn this study, we proposed a two-schema model that has the habitat filtering component and the stochastic component to construct the species assemblages seen in the community level. The proposed model uses one additional parameter (i.e. number of individuals in habitat) in addition to Hubbell’s three-parameter neutral model (i.e. fundamental bio-diversity number (θ), dispersal limitation (m) and speciation (v)). The proposed model works at two spatial scales: habitat filtering at the intermediate scales and stochastic processes at the large and very small spatial scales. The model coupled the local community dynamics with the meta-community dynamics. The local community has a fixed area with carrying capacity that is proportional to the local community size. The number of habitats in the proposed model can vary. Individuals are placed into habitats with probabilities according to the habitat suitability. Species richness and species composition in each habitat were calculated. The model is fitted for different θ values, m values, and a different number of habitats.ConclusionsWe assume that habitat filtering plays an important role together with stochastic processes to structure species in forests. Therefore, the proposed model with only four parameters can explain a large proportion of the species structuring of the communities. We found that more species can be maintained in a heterogeneous environment than a uniform environment. Therefore, habitat conservation is highly important for maintaining species diversity in forest communities.

Acoustic Monitoring Reveals a Diverse Forest Owl Community, Illustrating Its Potential for Basic and Applied Ecology

Bioacoustic surveys are an increasingly common tool for wildlife research due to increasing software performance and decreasing hardware costs. We conducted landscape-scale passive acoustic surveys across the northern Sierra Nevada to assess the distribution and density of barred owls (Strix varia) at the leading edge of their ongoing range expansion. From the resulting audio, we derived occupancy data on barred owls and spotted owls (S. occidentalis). We also documented seven other owl species; because the audio was passively recorded, it will be possible to extract systematic monitoring data on those nine species and others. Our findings reveal the tremendous latent potential of passively recorded acoustic survey data for studying otherwise cryptic species and biological communities. Photo credit: Connor M. Wood. Photo credit: Connor M. Wood. These photographs illustrate the article “Acoustic monitoring reveals a diverse forest owl community, illustrating its potential for basic and applied ecology” by Connor M. Wood, R.J. Gutiérrez, and M. Zachariah Peery published in Ecology. https://doi.org/10.1002/ecy.2764

Neighborhood effects explain increasing asynchronous seedling survival in a subtropical forest

Biotic interactions play a critical role in mediating community responses to temporal environmental variation, but the importance of these effects relative to the direct effects of environmental change remains poorly understood, particularly in diverse forest communities. Here we combine a neighborhood modeling approach with insights from coexistence theory to assess the effects of temporal variation in species interactions and environmental conditions (e.g., precipitation, temperature, and understory light availability) on seedling survival over nine census years in a subtropical forest. We find significant temporal shifts in the magnitude of neighborhood effects on both community-wide and species-level seedling survival (statistically significant random effects of neighborhood × year and neighborhood × species × year interactions). These results are consistent with the idea that environmental change will play a fundamental role on forest regeneration dynamics by altering biotic interactions at the neighborhood scale. Moreover, differences among species in response to neighbors over time contribute to a pattern of temporal decoupling of seedling survival between species, which can help to promote diversity in certain contexts. In separate analyses of multiple regression on distance matrices (MRM), altered interactions with neighbors are much stronger predictors of asynchronousseedling survival among species than the pure effects of climate and plant functional traits, explaining twice as much variation (43.9% vs. 22.2%). In sum, these results reveal that divergent species responses to interannual environmental variability detected are driven primarily by indirect effects mediated by changing biotic environments. This highlights the importance of including indirect effects from local biotic (neighborhood) interactions in forecasts of forest community responses to global change.