Functional Community Composition Research Articles

The impact of pine wilt disease on the endophytic microbial communities structure of Pinus koraiensis

Pine Wilt Disease (PWD) is a devastating pine tree disease characterized by rapid onset, high mortality rate, quick spread, and difficulty in control. Plant microbiome plays a significant role in the development of PWD. However, the endophytic microbial communities of Pinus koraiensis infected by pine wood nematode (PWN) Bursaphelenchus xylophilus remain largely unexplored. In this study, we analyzed the structural changes of endophytic communities of P. koraiensis after infection by the PWN using high-throughput sequencing technology. The results showed that the community structure underwent significant changes as the degree of PWN infection intensified. The diversity and abundance of endophytic fungi in P. koraiensis increased, while those of endophytic bacteria in P. koraiensis decreased during the infection process. Meanwhile, the abundance of some dominant microorganisms has also changed, including species such as Graphilbum and Pseudoalteromonas. Functional prediction analysis showed that the functional composition of endophytic fungi in P. koraiensis was significantly different across the development of PWD, while the composition of endophytic bacteria remained essentially similar. The results indicated that PWN infection had a significant impact on the structure, diversity, abundance, and functional gene composition of endophytic microbial communities in P. koraiensis, and most of the main endophytic microbial groups tended to coordinate with each other. This work provides a better understanding of the changes in endophytic community structure and function caused by PWD infection of P. koraiensis, which may benefit the exploration of potential endophytes for PWN biocontrol.

Naturalized species drive functional trait shifts in plant communities

Despite decades of research documenting the consequences of naturalized and invasive plant species on ecosystem functions, our understanding of the functional underpinnings of these changes remains rudimentary. This is partially due to ineffective scaling of trait differences between native and naturalized species to whole plant communities. Working with data from over 75,000 plots and over 5,500 species from across the United States, we show that changes in the functional composition of communities associated with increasing abundance of naturalized species mirror the differences in traits between native and naturalized plants. We find that communities with greater abundance of naturalized species are more resource acquisitive aboveground and belowground, shorter, more shallowly rooted, and increasingly aligned with an independent strategy for belowground resource acquisition via thin fine roots with high specific root length. We observe shifts toward herbaceous-dominated communities but shifts within both woody and herbaceous functional groups follow community-level patterns for most traits. Patterns are remarkably similar across desert, grassland, and forest ecosystems. Our results demonstrate that the establishment and spread of naturalized species, likely in combination with underlying environmental shifts, leads to predictable and consistent changes in community-level traits that can alter ecosystem functions.

Subtle changes in plant diversity in the Bavarian Alps over the past eight decades.

Historical resurveys represent a unique opportunity to analyze vegetation dynamics over longer timescales than is typically achievable. Leveraging the oldest historical dataset of vegetation change in the Bavarian Alps, Germany, we address how environmental conditions, vegetation composition, and functional diversity in the calcareous grasslands of the Schachen region have changed across different elevational ranges over an 83-year timeframe. We document changes in regional average temperature and precipitation. We use indicator values (IV) for species' ecological preferences and their palatability to grazers to infer local conditions (temperature, soil moisture/fertility, and grazing regime). We further estimate changes in temporal beta-diversity and functional trait community composition between historical (1936) and contemporary (2019) surveys in two elevational (subalpine and alpine) belts. Both subalpine and alpine sites became drier; subalpine sites also became warmer with more palatable plants. Species occurrence and abundance in the Schachen region has not changed substantially over time despite changing macroclimate and local environmental conditions under anthropogenic change. Yet these grasslands have experienced several "invisible" changes in functional composition over the past 80 years. As the Schachen has become drier, species with traits related to drought tolerance and animal-based dispersal have increased in dominance. Specifically, in alpine sites, community-weighted means revealed that with low fecundity, higher potential for endo- and epizoochory (seed dispersal via animal gut and fur, respectively), higher foliar frost tolerance, and deeper dormancy increased in dominance. Similar trends were found for increasing dominance of low fecundity, epizoochorous species in subalpine sites. Vegetation data from resurveying historical plots in combination with changes in local conditions, classic biodiversity indices, and functional trait indices can provide more holistic insights into changes in the environment and potential impacts of those environmental changes on long-term plant community and functional diversity.

Differential responses of community‐level functional traits to mid‐ and late‐season experimental drought in a temperate grassland

Abstract Extreme precipitation events are becoming more intense and frequent due to climate change. This climatic shift is impacting the structure and dynamics of natural communities and the key ecosystem services they provide. Changes in species abundance under these conditions are thought to be mediated by functional traits, morpho‐physiological characteristics of an organism that impact its fitness. Future environmental conditions may, therefore, favour different traits to those in present‐day communities. After 6 years of manipulated precipitation levels, including drought (−50% of ambient precipitation), irrigation (+50% of ambient precipitation), and control (ambient precipitation), we measured five key functional traits (plant height, leaf dry matter content [LDMC], leaf thickness, specific leaf area [SLA], and leaf phosphorus concentration) in 586 individual vascular plants to study the effects of precipitation changes on community‐weighted functional traits. Additionally, we tested whether the precipitation change effects on the traits depend on the time of the growing season. As expected, reduced precipitation impacted community composition only for the late‐season timing, after the seasonal field mowing, but led to a significant change in all community‐level plant traits between season timings. Under drought, communities shifted towards shorter individuals with thicker but small leaves and lower phosphorous content. Overall, a combination of community reassembly and intraspecific variation contributed to community‐weighted differences between control and drought plots for plant height, SLA, and LDMC traits. Species turnover was the main driver of community‐weighted means (CWMs) shifts in all traits in the late‐season but SLA. Whereas all traits showed variations at the community level with drought, SLA and LDMC were the most responsive traits at the species level. Nevertheless, our results suggest underestimation of intraspecific variation due to sensitive species lower abundance under stress. No differences in CWMs of functional traits were observed between control and irrigated plots. Synthesis: Our findings suggest that functional trait composition of grassland communities may shift under climate change‐induced drought, depending on the growing season timings. Trait‐based attempts to predict ecosystem functioning must account for such temporal variation in community trait values.

Soil pathogenic fungal groups and soil nutrient cycling under land use practices in Liupanshan Mountain in China

AbstractDifferent land‐use practices in temperate forests strongly affect soil quality and soil microbial communities, whereas the assembly and interactions of soil functional fungal communities provide positive feedback. Therefore, the effects of forest ecosystem degradation on the composition of functional soil fungal community and soil nutrient cycling are of particular importance. We studied forest ecosystems in the Liupanshan Mountains in the northwestern part of the Loess Plateau and analyzed the relationship of soil fungal community and soil nutrient cycling under different land use practices (natural forest [NF], plantation forest, and farmland [FL]). The results showed that soil pH and electrical conductivity were the highest in FL, whereas the soil carbon cycle index and nitrogen cycle index decreased. The soil total phosphorus content did not change significantly with an increase in available phosphorus content. The change from NF to FL significantly increased the number of operational taxonomic units, diversity, and richness of soil fungal communities. The composition of the soil fungal communities was also strongly influenced by carbon and nitrogen cycle indices. In addition, FL reclamation increased the complexity of the soil microorganism co‐occurrence network, and the interrelationships between soil functional fungal community were enhanced. Pathogenic fungal communities were enriched in FLs, and their relative abundance was significantly regulated by environmental factors such as pH and the ratio of nitrogen to phosphorus. The soil pathogenic fungal community affected carbon and nitrogen cycle indices to varying degrees.

Perturbations to common gardens of anaerobic co-digesters reveal relationships between functional resilience and microbial community composition.

We report the relationship between enrichment of adapted populations and enhancement of community functional resilience in methanogenic bioreactors. Although previous studies have shown the positive effects of acclimation, this work directly investigated the relationships between microbiome dynamics and performance of anaerobic co-digesting reactors in response to different levels of an environmental perturbation (loading of grease interceptor waste [GIW]). Using the methanogenic microbiome from a full-scale digester, we developed eight sets of microbial communities in triplicate using different feed sources. These substrate-specific microbiomes were then exposed to three independent disturbance events of low-, mid- and high-GIW loading rates. This approach allowed us to directly attribute differences in community responses to differences in community composition. Despite identical inocula, environment (digester operation, substrate loading rate, and feeding patterns) and general whole-community function (methane production and effluent quality) during the cultivation period, different substrates led to different microbial community assemblies. Lipid pre-acclimation led to enrichment of a pool of specialized populations, along with thriving of sub-dominant communities. The enrichment of these populations improved functional resilience and process performance when exposed to a low level of lipid-rich perturbation compared with less-acclimated communities. At higher levels of perturbation, the communities were not able to recover methanogenesis, indicating a loading limit to the resilience response. This study extends our current understanding of environmental perturbations, feed-specific adaptation, and functional resilience in methanogenic bioreactors.IMPORTANCEThis study demonstrates, for the first time for GIW co-digestion, how applying similar perturbations to different microbial communities was used to directly identify the causal relationships between microbial community, function, and environment in triplicate anaerobic microbiomes. We evaluated the impact of feed-specific adaptation on methanogenic microbiomes and demonstrated how microbiomes can be influenced to improve their functional (methanogenic) resilience to GIW inhibition. These findings demonstrate how an ecological framework can help improve a biological engineering application, and more specifically, increase the potential of anaerobic co-digestion for converting wastes to energy.

Synergistic changes in bacterial community composition, function, and soil characteristics of tomato rhizosphere soil under long-term monoculture conditions

Tomato is widely cultivated all over the world, and long-term monoculture has resulted in decreased tomato yields and stunted plant growth. Soil bacterial communities have a profound effect on plant growth and health, and the effect of different planting years on rhizosphere soil microorganisms of tomato is not clear. In this study, metagenomic sequencing was used to analyze the rhizosphere soil microorganisms of tomatoes cultivated continuously for 3, 6 years (short-term continuous cropping), 9, and 12 years (long-term continuous cropping) (LZ3, LZ6, LZ9, LZ12). The results showed that the pH in LZ9 was significantly higher than that in the other treatments, the relative abundance of Planctomycetes and Candidatus Rokubacteria in LZ3 were higher than those in the other treatments, the relative abundance of Proteobacteria was significantly higher in LZ6 and LZ9 than that in the other treatments, and the relative abundance of Chloroflexi and Bacteroidetes in LZ12 were higher than those in the other treatments. At the genus level, the relative abundance of Nocardioides, Sphingomonas, Pseudolabrys were lower in LZ3 than that in other treatments, and the relative abundance of Gaiella was significantly higher in short-term continuous cropping than that in LZ9. The pH, hydrolyzable nitrogen (HN), and available potassium (AK) were the most important factors driving the changes in microbial communities. The relative abundance of amino acid metabolism, terpenoid and polyketide metabolism decreased significantly with years of continuous cropping, and that total nitrogen (TN), HN, and available phosphorus (AP) were significantly correlated with translation, amino acid metabolism, and cell growth and death. Continuous cropping leads to nutrient imbalance in tomato soils, which affects the structure and functional composition of soil microbial communities, providing insights into microbial community response to continuous tomato cropping, but further in-depth studies are needed.

Global patterns in the growth potential of soil bacterial communities

Despite the growing catalogue of studies detailing the taxonomic and functional composition of soil bacterial communities, the life history traits of those communities remain largely unknown. This study analyzes a global dataset of soil metagenomes to explore environmental drivers of growth potential, a fundamental aspect of bacterial life history. We find that growth potential, estimated from codon usage statistics, was highest in forested biomes and lowest in arid latitudes. This indicates that bacterial productivity generally reflects ecosystem productivity globally. Accordingly, the strongest environmental predictors of growth potential were productivity indicators, such as distance to the equator, and soil properties that vary along productivity gradients, such as pH and carbon to nitrogen ratios. We also observe that growth potential was negatively correlated with the relative abundances of genes involved in carbohydrate metabolism, demonstrating tradeoffs between growth and resource acquisition in soil bacteria. Overall, we identify macroecological patterns in bacterial growth potential and link growth rates to soil carbon cycling.

Decoupling soil community structure, functional composition, and nitrogen metabolic activity driven by salinity in coastal wetlands

Coastal wetlands, being a multifaceted and crucial global ecosystem, are facing significant impacts from diverse environmental alterations, particularly soil salinization. Concurrently, the escalation of extreme climate events, such as global warming, presents complex challenges for the protection and restoration efforts. Previous researches concerning microbial communities in the context of climate with continous line numbering change have predominantly concentrated on their structural aspects, with limited attention given to establishing relationships between community structure and functional attributes. In this study, a two-year investigation was conducted on conventional coastal wetland ecosystems, considering variations in salinity and seasonal temperature. Utilizing high-throughput 16S rRNA sequencing, isotope technology, and other methods to explore the bacterial community, nitrogen cycling functional groups, and nitrogen reduction process. This research aims to assess the holistic impacts of significant global environmental changes on microbial communities. The results suggest that salinity, acting as an environmental filter, has a significant impact on the microbial community composition. It leads to a decrease in species abundance, an increase in deterministic processes and the nesting of community succession, while also reducing the stability of microbial ecological networks. The mechanism by which soil salinity impacts bacterial communities involves three main aspects: direct effects, positive climate regulation, and negative regulation of soil properties. Surprisingly, soil salinity exerts a mild inhibitory influence on microbial functional genes and metabolic activity. The primary factors involved in the nitrogen reduction process include electron donors/acceptors, types of nitrogen sources, and organic carbon. The three processes are interconnected due to the impact of environmental factors and signal transmission among microbial populations. This study offers a novel scientific framework for the rehabilitation and enhancement of saline-alkali coastal ecosystems in the face of impending global changes. It achieves this by investigating the varied response patterns exhibited by microbial communities and ecological functional metabolism under salinity-induced stress.

Context specific effects of substrate composition on the taxonomic and functional diversity of macroinvertebrate communities in temperate lowland streams.

Substrate composition has been widely recognised as a primary variable shaping lotic macroinvertebrate communities at the habitat unit level. However, fundamental understanding of how communities inhabiting mineralogical habitats (i.e., gravel, sand and silt) are structured across differing rivers is lacking. Moreover, research largely focusses on gravel beds and fine sediment in general (<2 mm) and as a result detailed field observations specifically of the sand and silt fractions are lacking. Using data from five UK streams collated from published studies, we assess taxonomic and functional biodiversity (alpha and beta diversity) at the habitat unit level (as defined by substrate composition of sand, silt and gravel). We found that the composition of taxonomic communities were clearly different in all habitat units for each individual stream (and at the landscape scale), with comparable, but less strong, distinctions between substrates for functional macroinvertebrate community composition. However, alpha diversity metrics and Local Contribution to Beta Diversity (LCBD) recorded among the different habitat units varied significantly across individual rivers, and the amount of variation explained by the habitat unit for taxonomic and functional composition demonstrated considerable differences suggesting strong context dependence. The depositional fine sediment habitats of sand and silt were found to support a discrete community composition and differing levels of alpha and beta diversity within and between rivers. We advocate that care should be taken when seeking to generalise biodiversity patterns at a landscape scale as our study highlights the high degree of context dependency when considering the role of the habitat template. Moreover, our results provide evidence that discriminating between the size fractions of fine sediment habitats (sand or silt) is important to fully elucidate the wider ecological importance of these habitats and the distinct taxonomic and functional biodiversity they support.

Long‐term changes in taxonomic and functional composition of European marine fish communities

Evidence of large‐scale biodiversity degradation in marine ecosystems has been reported worldwide, yet most research has focused on few species of interest or on limited spatiotemporal scales. Here we assessed the spatial and temporal changes in the taxonomic and functional composition of fish communities in European seas over the last 25 years (1994–2019). We then explored how these community changes were linked to environmental gradients and fishing pressure. We show that the spatial variation in fish species composition is more than two times higher than the temporal variation, with a marked spatial continuum in taxonomic composition and a more homogenous pattern in functional composition. The regions warming the fastest are experiencing an increasing dominance and total abundance of r‐strategy fish species (lower age of maturity). Conversely, regions warming more slowly show an increasing dominance and total abundance of K‐strategy species (high trophic level and late reproduction). Among the considered environmental variables, sea surface temperature, surface salinity and chlorophyll‐a most consistently influenced communities' spatial patterns, while bottom temperature and oxygen had the most consistent influence on temporal patterns. Changes in communities' functional composition were more closely related to environmental conditions than taxonomic changes. Our study demonstrates the importance of integrating community‐level species traits across multi‐decadal scales and across a large region to better capture and understand ecosystem‐wide responses and provides a different lens on community dynamics that could be used to support sustainable fisheries management.

Long-Term Contaminant Exposure Alters Functional Potential and Species Composition of Soil Bacterial Communities in Gulf Coast Prairies.

Environmental pollution is a persistent threat to coastal ecosystems worldwide, adversely affecting soil microbiota. Soil microbial communities perform critical functions in many coastal processes, yet they are increasingly subject to oil and heavy metal pollution. Here, we assessed how small-scale contamination by oil and heavy metal impacts the diversity and functional potential of native soil bacterial communities in the gulf coast prairie dunes of a barrier island in South Texas along the northern Gulf of Mexico. We analyzed the bacterial community structure and their predicted functional profiles according to contaminant history and examined linkages between species diversity and functional potential. Overall, contaminants altered bacterial community compositions without affecting richness, leading to strongly distinct bacterial communities that were accompanied by shifts in functional potential, i.e., changes in predicted metabolic pathways across oiled, metal, and uncontaminated environments. We also observed that exposure to different contaminants can either lead to strengthened or decoupled linkages between species diversity and functional potential. Taken together, these findings indicate that bacterial communities might recover their diversity levels after contaminant exposure, but with consequent shifts in community composition and function. Furthermore, the trajectory of bacterial communities can depend on the nature or type of disturbance.

Functional responses of understory plants to natural disturbance-based management in eastern and western Canada.

Natural disturbance-based management (NDBM) is hypothesized to maintain managed forest ecosystem integrity by reducing differences between natural and managed forests. The effectiveness of this approach often entails local comparisons of species composition or diversity for a variety of biota from managed and unmanaged forests. Understory vegetation is regularly the focus of such comparison because of its importance in nutrient cycling, forest regeneration, and for wildlife. However, larger scale comparisons between regions with distinct species assemblages may require a trait-based approach to better understand understory responses to disturbance. We compared the long-term effects of retention harvesting on understory vegetation in two large experimental study sites located in eastern and western regions of the Canadian boreal forest. These sites included the Sylviculture en Aménagement Forestier Ecosystémique (SAFE) experiment and the Ecosystem Management Emulating Natural Disturbance (EMEND) experiment, located in the eastern and western regions of Canada, respectively. EMEND and SAFE share common boreal understory species but have distinct tree communities, soils, and climate. Both experiments were designed to evaluate how increasing tree retention after harvest affects biodiversity. Here, we examined taxonomic richness, functional diversity, and functional composition (using community trait mean values) of understory plant communities, and also examine intraspecific trait variability (ITV) for five species common and abundant in both experiments. We observed the limited impacts of retention level on richness, functional diversity, and functional composition of understory plants 20 years postharvest. However, ITV of leaf morphological traits varied between retention levels within each experiment, depending on the species identity. Common species had different functional responses to retention level, showing species-specific reactions to environmental variation. Our result suggests that understory plant communities in the boreal forest achieve resilience to disturbance both in terms of interspecific and intraspecific functional trait diversity. Such diversity may be key to maintaining understory biodiversity in the face of future disturbances and environmental change. Our results reveal the significance of ITV in plant communities for understanding responses to forest harvesting and the importance of choosing appropriate traits when studying species responses to the environment.

Functional diversity of neighbours mediates sap flow density and radial growth of focal trees, but in different ways between evergreen and deciduous broadleaved species

Abstract The functioning of a tree is shaped by the neighbouring species through the interspecific interaction and local environments. The functional trait composition of the neighbourhood could provide mechanistic insights into the effects of neighbours on the resource strategies of focal trees. In this study, we deployed an automated high‐frequency measurement of the sap flow density (SFD) and the radial growth of 48 trees of 12 species at BEF‐China, a large‐scale forest biodiversity manipulation experiment, to investigate the consequences and underlying mechanisms of the functional trait composition of the neighbourhood on the sap flow and radial growth of focal trees. We found a positive relationship between SFD and growth, reflecting the important supportive role of sap flow in tree growth. High functional diversity (FD) of the neighbourhood depressed SFD but promoted growth when considering all species, and thus promoted water‐use efficiency. Acquisitiveness of neighbouring trees positively affected growth, suggesting interspecific facilitation. Furthermore, neighbourhood FD benefits evergreen focal trees by promoting growth. However, in deciduous focal trees, neighbourhood FD reduced SFD but had no significant effects on growth. Our findings suggest that considering the functional trait composition of neighbourhood communities will support effective afforestation and forest management. Read the free Plain Language Summary for this article on the Journal blog.

A common ericoid shrub modulates the diversity and structure of fungal communities across an arbuscular to ectomycorrhizal tree dominance gradient.

Differences between arbuscular (AM) and ectomycorrhizal (EcM) trees strongly influence forest ecosystem processes, in part through their impact on saprotrophic fungal communities. Ericoid mycorrhizal (ErM) shrubs likely also impact saprotrophic communities given that they can shape nutrient cycling by slowing decomposition rates and intensifying nitrogen limitation. We investigated the depth distributions of saprotrophic and EcM fungal communities in paired subplots with and without a common understory ErM shrub, mountain laurel (Kalmia latifolia L.), across an AM to EcM tree dominance gradient in a temperate forest by analyzing soils from the organic, upper mineral (0-10cm), and lower mineral (cumulative depth of 30cm) horizons. The presence of K. latifolia was strongly associated with the taxonomic and functional composition of saprotrophic and EcM communities. Saprotrophic richness was consistently lower in the Oa horizon when this ErM shrub species was present. However, in AM tree-dominated plots, the presence of the ErM shrub was associated with a higher relative abundance of saprotrophs. Given that EcM trees suppress both the diversity and relative abundance of saprotrophic communities, our results suggest that separate consideration of ErM shrubs and EcM trees may be necessary when assessing the impacts of plant mycorrhizal associations on belowground communities.

Examining functional responses of ant communities to fire in Northwestern African afforested landscapes

In fire prone-regions, forest fires play a vital role in shaping animal communities, particularly for groups like ants strongly associated with vegetation and soil. While prior works on the impact of forest fires on biodiversity focused on taxonomic responses, there is a growing interest on exploring functional responses. This study assesses the taxonomic and functional response of ant species to fire in afforested landscapes (pine plantations) in northern Morocco. These landscapes are widely recognized as suboptimal for many taxonomic groups, suggesting a positive responses of ant communities to fire. Our specific hypotheses were: (1) increasing post-fire openness enhances the richness and abundance of ant species in burnt plots, and (2) fire induces shifts in functional traits within ant communities influencing their composition, potentially favoring species with adaptations suited to the post-fire environment. Our results reveal that fire altered the taxonomic (winner and loser ant species) and functional composition (higher functional richness in burnt plots) of ant communities. Burnt areas harbored a greater abundance of ant species adapted to open habitats, characterized by ground nesting habits, ground foraging, and a preference for readily available resources like seeds. In contrast, unburnt plots hosted species ideally adapted to denser vegetation, utilizing arboreal nesting and foraging strategies and resource niches in the canopy. Overall, we found that fire significantly shapes ant communities by promoting the arrival of species tolerant of open areas and capable of exploiting new available resources in the post-fire habitat.

Giant root-rat engineering and livestock grazing activities regulate plant functional trait diversity of an Afroalpine vegetation community in the Bale Mountains, Ethiopia

Disturbances from rodent engineering and human activities profoundly impact ecosystem structure and functioning. Whilst we know that disturbances modulate plant communities, comprehending the mechanisms through which rodent and human disturbances influence the functional trait diversity and trait composition of plant communities is important to allow projecting future changes and to enable informed decisions in response to changing intensity of the disturbances. Here, we evaluated the changes in functional trait diversity and composition of Afroalpine plant communities in the Bale Mountains of Ethiopia along gradients of engineering disturbances of a subterranean endemic rodent, the giant root-rat (Tachyoryctes macrocephalus Rüppell 1842) and human activities (settlement establishment and livestock grazing). We conducted RLQ (co-inertia analysis) and fourth-corner analyses to test for trait-disturbance (rodent engineering/human activities) covariation. Overall, our results show an increase in plant functional trait diversity with increasing root-rat engineering and increasing human activities. We found disturbance specific association with traits. Specifically, we found strong positive association of larger seed mass with increasing root-rat fresh burrow density, rhizomatous vegetative propagation negatively associated with increasing root-rat old burrow, and stolonifereous vegetative propagation positively associated with presence of root-rat mima mound. Moreover, both leaf size and leaf nitrogen content were positively associated with livestock dung abundance but negatively with distance from settlement. Overall, our results suggest that disturbances by rodents filter plant traits related to survival and reproduction strategies, whereas human activities such as livestock grazing act as filters for traits related to leaf economics spectrum along acquisitive resource-use strategy.

Crop type rather than production method determines functional trait composition of insect communities on arable land in boreal agricultural landscapes

Abstract To understand the potential consequences of arable land use changes for insect conservation and ecosystem functioning, it is fundamental to know how insect species with different functional traits respond to crop choice and production method. This study examined the effects of crop type and production method on functional traits of butterfly, bumblebee and carabid beetle communities using species abundance data from 78 fields in Southern Finland. Surrounding landscape composition was also accounted for. The studied traits were associated with dispersal capacity, habitat or diet specialization and phenology—the key determinants modifying species responses to agricultural disturbances and land use changes. Butterfly habitat breadth was narrowest and wingspan shortest in long‐term fallows. Fallows also supported the highest share of butterflies overwintering in early development stages and bumblebees with late‐emerging queens. The tongue length of bumblebees was longest in organic oat fields, probably due to flowering weeds with long corolla. For carabid beetles, the proportion of poor flyers and carnivores was highest in perennial crops and fallows. Carabid beetles overwintering as adults were relatively more abundant in organic than in conventional production, probably due to more intensive tillage in organic fields. In all insect groups, poor dispersers and/or specialists decreased with increasing arable land cover in the surrounding landscape. Increasing the area of long‐term fallows and perennial crops and enhancing within‐field plant diversity while maintaining landscape heterogeneity would promote insect species sensitive to agricultural disturbances and land use changes and their associated ecosystem services in boreal farmland.

Trait-dependent importance of intraspecific variation relative to species turnover in determining community functional composition following nutrient enrichment.

Community weighted mean trait, i.e., functional composition, has been extensively used for upscaling of individual traits to the community functional attributes and ecosystem functioning in recent years. Yet, the importance of intraspecific trait variation relative to species turnover in determining changes in CWM still remains unclear, especially under nutrient enrichment scenarios. In this study, we conducted a global data synthesis analysis and three nutrient addition experiments in two sites of alpine grassland to reveal the extent to which species turnover and ITV contribute to shift in CWM in response to nutrient enrichment. The results consistently show that the importance of ITV relative to species turnover in regulating CWM in response to nutrient enrichment strongly depends on trait attributes rather than on environmental factors (fertilization type, climatic factors, soil properties, and light transmittance). For whole plant traits (height) and leaf morphological traits, species turnover is generally more important than ITV in determining CWM following most treatments of nutrient addition. However, for leaf nutrient traits, ITV outweighed species turnover in determining shifts in CWM in response to almost all treatments of nutrient addition, regardless of types and gradients of the nutrient addition. Thus, our study not only provides robust evidence for trait-dependent importance of ITV in mediating community functional composition, but also highlights the need to consider the nature of functional traits in linking ITV to community assembly and ecosystem functioning under global nutrient enrichment scenarios.

Shrubs exhibit competitive interactions with herbaceous plants and shape community assemblage and functional composition in the alpine western Himalaya

AbstractQuestionsIn the alpine region of the Himalaya, shrubs play a vital role in maintaining the diversity and functional composition of associated herbaceous communities through competition–facilitation interactions under varying environmental stress conditions. In this study, we specified the following questions: (1) what is the mode of interaction between dominant shrubs and the associated herbaceous communities; (2) how do differences in resource availability between contrasting microhabitats mediate interactions between shrub and herbaceous communities; and (3) how do dominant shrubs influence the functional composition of herbaceous communities under the canopy as compared to ones in the open?Study areaAn alpine region of the western Himalaya, in India (32.24–33.15° N, 76.51–78.13° E).MethodsField studies were conducted to evaluate the canopy effects of alpine shrubs such as Caragana versicolor, Juniperus polycarpos and Rhododendron anthopogon on species richness, abundance and functional composition of coexisting herbaceous communities.ResultsThe dominant alpine shrubs of the western Himalaya exert competitive interactions with associated herbaceous communities and have low species richness and abundance under their canopies compared to open habitats. Further, contrary to expectations, competitive interactions were more prominent at higher elevations than at lower ones, especially for J. polycarpos and C. versicolor. Although the shrub undercanopies possessed richer soil nutrient pools, this did not contribute toward the facilitation of herbaceous species under the canopies. Moreover, herbaceous species under the canopies were found to exhibit resource‐acquisitive functional strategies, whereas those in the open were resource‐conservative.ConclusionsThe interaction between dominant alpine shrubs and the herbaceous community of the western Himalaya is competitive in nature, which influences species and functional composition and reorganizes herbaceous community assembly. Moreover, under future climate change scenarios the dominance of these shrubs will favour those herbaceous species that possess more competitive and resource‐acquisitive functional strategies.