scholarly journals Phylogenetic and Functional Traits Verify the Combined Effect of Deterministic and Stochastic Processes in the Community Assembly of Temperate Forests along an Elevational Gradient

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 591
Author(s):  
Wensong Zhou ◽  
Yuxin Zhang ◽  
Shuang Zhang ◽  
Basil N. Yakimov ◽  
Keming Ma
Keyword(s):  
Stochastic Processes ◽  
Functional Traits ◽  
Community Assembly ◽  
Woody Plants ◽  
Elevational Gradient ◽  
Combined Effect ◽  
Abiotic Environment ◽  
Spatial Factors ◽  
Assembly Mechanism ◽  
Deterministic Processes

Explaining community assembly mechanisms along elevational gradients dominated by deterministic processes or stochastic processes is a pressing challenge. Many studies suggest that phylogenetic and functional diversity are significant indicators of the process. In this study, we analyzed the structure and beta diversity of phylogenetic and functional traits along an elevational gradient and discussed the effects of environmental and spatial factors. We found that the phylogenetic and functional traits showed inconsistent changes, and their variations were closely related to the abiotic environment. The results suggested that the community assembly of woody plants was obviously affected by the combined effect of deterministic processes and the stochastic hypothesis (primarily by the latter). Phylogenetic and functional traits had a certain relationship but changed according to different rules. These results enhance our understanding of the assembly mechanism of forest communities by considering both phylogenetic and functional traits.

scholarly journals Deterministic Selection Dominates Microbial Community Assembly in Termite Mounds Across a Large Spatial Area

2020 ◽  
Author(s):  
Qing-Lin Chen ◽  
Hang-Wei Hu ◽  
Zhen-Zhen Yan ◽  
Chao-Yu Li ◽  
Bao-Anh Thi Nguyen ◽  
...  
Keyword(s):  
Microbial Community ◽  
Stochastic Processes ◽  
Microbial Communities ◽  
Fungal Community ◽  
Community Assembly ◽  
Distance Decay ◽  
Termite Mounds ◽  
Deterministic Processes ◽  
Microbial Community Assembly

Abstract Background: Termites are ubiquitous insects in tropical and subtropical habitats, where they construct massive mounds from soil, their saliva and excreta. Termite mounds harbor an enormous amount of microbial inhabitants, which regulate multiple ecosystem functions such as mitigating methane emissions and increasing ecosystem resistance to climate change. However, we lack a mechanistic understanding about the role of termite mounds in modulating the microbial community assembly processes, which are essential to unravel the biological interactions of soil fauna and microorganisms, the major components of soil food webs. We conducted a large-scale survey across a >1500 km transect in northern Australia to investigate biogeographical patterns of bacterial and fungal community in 134 termite mounds and the relative importance of deterministic versus stochastic processes in microbial community assembly. Results: Microbial alpha (number of phylotypes) and beta (changes in bacterial and fungal community composition) significantly differed between termite mounds and surrounding soils. Microbial communities in termite mounds exhibited a significant distance-decay pattern, and fungal communities had a stronger distance-decay relationship (slope = -1.91) than bacteria (slope = -0.21). Based on the neutral community model (fitness < 0.7) and normalized stochasticity ratio index (NST) with a value below the 50% boundary point, deterministic selection, rather than stochastic forces, predominated the microbial community assembly in termite mounds. Deterministic processes exhibited significantly weaker impacts on bacteria (NST = 45.23%) than on fungi (NST = 33.72%), probably due to the wider habitat niche breadth and higher potential migration rate of bacteria. The abundance of antibiotic resistance genes (ARGs) was negatively correlated with bacterial/fungal biomass ratios, indicating that ARG content might be an important biotic factor that drove the biogeographic pattern of microbial communities in termite mounds. Conclusions: Deterministic processes play a more important role than stochastic processes in shaping the microbial community assembly in termite mounds, an unique habitat ubiquitously distributed in tropical and subtropical ecosystems. An improved understanding of the biogeographic patterns of microorganisms in termite mounds is crucial to decipher the role of soil faunal activities in shaping microbial community assembly, with implications for their mediated ecosystems functions and services.

Community assembly and species traits

2019 ◽  
pp. 231-246
Author(s):  
Gary G. Mittelbach ◽  
Brian J. McGill
Keyword(s):  
Functional Traits ◽  
Community Assembly ◽  
Species Traits ◽  
Fundamental Question ◽  
Species Pool ◽  
Environmental Filters ◽  
Abiotic Environment ◽  
Local Site ◽  
Powerful Approach ◽  
Regional Species Pool

There is perhaps no more fundamental question in ecology than what determines the number and kinds of species found in a community and their relative abundances. This chapter lays out a powerful approach to answering this question, based on the concepts of a regional species pool and environmental filters. The species pool is the set of species that could potentially colonize a local site or community. Of these potential colonists, some species are limited in their ability to disperse to site, some are limited by their ability to survive the abiotic environment, and some are limited by their interactions with other species. These “filters” act individually or in concert, and the functional traits of species determine their success in passing through these filters to colonize a local site. There is growing empirical evidence that both abiotic and biotic processes select for specific functional traits. Focusing on the functional traits of species may lead to rules of community assembly that are general and help unify a variety of more specific theories.

scholarly journals Aboveground and belowground arthropods experience different relative influences of stochastic versus deterministic community assembly processes following disturbance

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2545 ◽  
Author(s):  
Scott Ferrenberg ◽  
Alexander S. Martinez ◽  
Akasha M. Faist
Keyword(s):  
Community Structure ◽  
Stochastic Processes ◽  
Community Assembly ◽  
Tree Mortality ◽  
Mineral Soil ◽  
Relative Influence ◽  
Subalpine Forest ◽  
Arthropod Community ◽  
Arthropod Communities ◽  
Deterministic Processes

BackgroundUnderstanding patterns of biodiversity is a longstanding challenge in ecology. Similar to other biotic groups, arthropod community structure can be shaped by deterministic and stochastic processes, with limited understanding of what moderates the relative influence of these processes. Disturbances have been noted to alter the relative influence of deterministic and stochastic processes on community assembly in various study systems, implicating ecological disturbances as a potential moderator of these forces.MethodsUsing a disturbance gradient along a 5-year chronosequence of insect-induced tree mortality in a subalpine forest of the southern Rocky Mountains, Colorado, USA, we examined changes in community structure and relative influences of deterministic and stochastic processes in the assembly of aboveground (surface and litter-active species) and belowground (species active in organic and mineral soil layers) arthropod communities. Arthropods were sampled for all years of the chronosequence via pitfall traps (aboveground community) and modified Winkler funnels (belowground community) and sorted to morphospecies. Community structure of both communities were assessed via comparisons of morphospecies abundance, diversity, and composition. Assembly processes were inferred from a mixture of linear models and matrix correlations testing for community associations with environmental properties, and from null-deviation models comparing observed vs. expected levels of species turnover (Beta diversity) among samples.ResultsTree mortality altered community structure in both aboveground and belowground arthropod communities, but null models suggested that aboveground communities experienced greater relative influences of deterministic processes, while the relative influence of stochastic processes increased for belowground communities. Additionally, Mantel tests and linear regression models revealed significant associations between the aboveground arthropod communities and vegetation and soil properties, but no significant association among belowground arthropod communities and environmental factors.DiscussionOur results suggest context-dependent influences of stochastic and deterministic community assembly processes across different fractions of a spatially co-occurring ground-dwelling arthropod community following disturbance. This variation in assembly may be linked to contrasting ecological strategies and dispersal rates within above- and below-ground communities. Our findings add to a growing body of evidence indicating concurrent influences of stochastic and deterministic processes in community assembly, and highlight the need to consider potential variation across different fractions of biotic communities when testing community ecology theory and considering conservation strategies.

scholarly journals Is Phylogeny More Useful than Functional Traits for Assessing Diversity Patterns Under Community Assembly Processes?

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1159 ◽  
Author(s):  
Jinshi Xu ◽  
Han Dang ◽  
Mao Wang ◽  
Yongfu Chai ◽  
Yaoxin Guo ◽  
...  
Keyword(s):  
Functional Diversity ◽  
Functional Traits ◽  
Community Assembly ◽  
Phylogenetic Diversity ◽  
Environmental Changes ◽  
Taxonomic Diversity ◽  
Elevational Gradient ◽  
Functional Trait ◽  
Β Diversity ◽  
Α Diversity

Phylogenetic and functional diversities and their relationship are important for understanding community assembly, which relates to forest sustainability. Thus, both diversities have been used in ecological studies evaluating community responses to environmental changes. However, it is unclear whether these diversity measures can uncover the actual community assembly processes. Herein, we examined their utility to assess such assembly processes by analyzing similarities in phylogenetic, functional, and taxonomic α- and β-diversities along an elevational gradient. Additionally, we examined the relationships among environment, phylogeny, and functional traits within the community. Based on our results, we evaluated whether phylogenetic or functional diversity could better reveal the actual community assembly processes. We found that taxonomic, phylogenetic, and functional α-diversities were correlated with one another. Although the functional α-diversity showed a linear correlation with the elevational gradient, taxonomic and phylogenetic α-diversities showed unimodal patterns. Both phylogenetic and functional β-diversities correlated with taxonomic β-diversity, but there was no significant relationship between the former. Overall, our results evidenced that phylogenetic diversity and taxonomic diversity showed similar patterns, whereas functional diversity showed a relatively independent pattern, which may be due to limitations in the functional trait dimensions used in the present study. Although it is difficult to unravel whether the environment shapes phylogeny or functional traits within a community, phylogenetic diversity is a good proxy for assessing the assembly processes, whereas functional diversity may improve knowledge on the community by maximizing information about the functional trait dimensions.

Conservation and Restoration of Grasslands

2018 ◽  
Author(s):  
Brian J. Wilsey
Keyword(s):  
Community Assembly ◽  
Woody Plants ◽  
Woody Plant ◽  
Priority Effects ◽  
Woody Plant Encroachment ◽  
Humpty Dumpty ◽  
Alternate States ◽  
Density And Biomass ◽  
Acid Test ◽  
Stocking Rates

Conservation programs alter herbivore stocking rates and find and protect the remaining areas that have not been plowed or converted to crops. Restoration is an ‘Acid Test’ for ecology. If we fully understand how grassland systems function and assemble after disturbance, then it should be easy to restore them after they have been degraded or destroyed. Alternatively, the idea that restorations will not be equivalent to remnants has been termed the ‘Humpty Dumpty’ hypothesis—once lost, it cannot be put back together again. Community assembly may follow rules, and if these rules are uncovered, then we may be able to accurately predict final species composition after assembly. Priority effects are sometimes found depending on species arrival orders, and they can result in alternate states. Woody plant encroachment is the increase in density and biomass of woody plants, and it is strongly affecting grassland C and water cycles.

scholarly journals Aboveground and belowground arthropod communities experience different relative influences of stochastic and deterministic assembly processes following disturbance

2016 ◽  
Author(s):  
Scott Ferrenberg ◽  
Alexander S. Martinez ◽  
Akasha M. Faist
Keyword(s):  
Community Structure ◽  
Stochastic Processes ◽  
Community Assembly ◽  
Tree Mortality ◽  
Species Turnover ◽  
Mineral Soil ◽  
Relative Influence ◽  
Subalpine Forest ◽  
Arthropod Community ◽  
Arthropod Communities

Background. Understanding patterns of biodiversity is a longstanding challenge in ecology. Similar to other biotic groups, arthropod community structure can be shaped by deterministic and stochastic processes, with limited understanding of what moderates the relative influence of these processes. Disturbances have been noted to alter the relative influence of deterministic and stochastic processes on community assembly in various study systems, implicating ecological disturbances as a potential moderator of these forces. Methods. Using a disturbance gradient along a 5-year chronosequence of insect-induced tree mortality in a subalpine forest of the southern Rocky Mountains, Colorado, USA, we examined changes in community structure and relative influences of deterministic and stochastic processes in the assembly of aboveground (surface and litter-active species) and belowground (species active in organic and mineral soil layers) arthropod communities. Arthropods were sampled for all years of the chronosequence via pitfall traps (aboveground community) and modified Winkler funnels (belowground community) and sorted to morphospecies. Community structure of both communities were assessed via comparisons of morphospecies diversity and assemblages. Assembly processes were inferred from a mixture of linear models and matrix correlations testing for community associations with environmental properties, and from null-deviation models calculated from observed vs. expected levels of species turnover (Beta diversity) among samples. Results. Tree mortality altered community structure in both aboveground and belowground arthropod communities, but null models suggested that aboveground communities experienced greater relative influences of deterministic processes, while the relative influence of stochastic processes increased for belowground communities. Additionally, Mantel tests and linear regression models revealed significant associations between the aboveground arthropod communities and vegetation and soil properties, but no significant association among belowground arthropod communities and environmental factors. Discussion. Our results suggest context-dependent influences of stochastic and deterministic community assembly processes across different fractions of a ground-dwelling arthropod community following a disturbance. This variation in assembly may be linked to contrasting ecological strategies and dispersal rates within above- and below-ground communities. Our findings add to a growing body of evidence indicating concurrent influences of different processes in community assembly, and highlight the need to consider potential variation across different fractions of biotic communities when testing community ecology theory.

scholarly journals Coupling Bacterial Community Assembly to Microbial Metabolism across Soil Profiles

mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Lu Luan ◽  
Chao Liang ◽  
Lijun Chen ◽  
Haotian Wang ◽  
Qinsong Xu ◽  
...  
Keyword(s):  
Microbial Community ◽  
Bacterial Community ◽  
Community Assembly ◽  
Carbon Metabolism ◽  
Structural Equation ◽  
Equation Modeling ◽  
Deep Soil ◽  
Deterministic Processes ◽  
Stochastic Dispersal ◽  
Microbial Community Assembly

ABSTRACT Soil microbial community assembly is crucial for understanding the mechanisms of microbial communities that regulate ecosystem-level functioning. The relative contributions of stochastic and deterministic processes to microbial community assembly remain poorly defined, and major questions exist concerning the soil organic carbon (SOC) dynamics of microbial community assembly in deep soil. Here, the bacterial community assembly processes were explored across five soil profile depths (up to 80 cm) during a 15-year field experiment involving four fertilization regimes. We found that the bacterial community assembly was initially governed by deterministic selection in topsoil but was progressively structured by increasing stochastic dispersal with depth. The migration rate (m) and β-null deviation pattern supported the hypothesis of a relatively greater influence of dispersal in deep soil, which was correlated with bacterial community assembly by stochastic processes. These changes in the entire community assembly reflected consistent assembly processes of the two most dominant phyla, Acidobacteria and Chloroflexi. Structural equation modeling showed that soil features (pH and total phosphorus) and bacterial interactions (competition and network complexity) were significantly related to bacterial community assembly in the 0-to-10-cm and 10-to-20-cm layers. Partial Mantel tests, structural equation modeling, and random forest modeling consistently indicated a strong and significant correlation between bacterial community assemblages and SOC dynamics, implying that bacterial assembly processes would potentially suppress SOC metabolism and mineralization when the contributions of stochastic dispersal to communities increased in deeper layers. Our results have important implications for integrating bacterial community assembly processes into the predictions of SOC dynamics. IMPORTANCE We have provided a framework to better understand the mechanisms governing the balance between stochastic and deterministic processes and to integrate the shifts in community assembly processes with microbial carbon metabolism. Our study reinforced that environmental filtering and bacterial cooccurrence patterns influence the stochastic/deterministic continuum of soil bacterial community assembly and that stochasticity may act through deeper soil layers to influence carbon metabolism. Delineating theoretically the potential linkages between community assembly and SOC dynamics across a broad range of microbial systems represents an interesting topic for future research.

scholarly journals A handbook for the standardised sampling of plant functional traits in disturbance-prone ecosystems, with a focus on open ecosystems

2020 ◽  
Vol 68 (8) ◽  
pp. 473
Author(s):  
B. J. Wigley ◽  
T. Charles-Dominique ◽  
G. P. Hempson ◽  
N. Stevens ◽  
M. TeBeest ◽  
...  
Keyword(s):  
Functional Traits ◽  
Woody Plants ◽  
Plant Functional Traits ◽  
Life Stages ◽  
Environmental Filters ◽  
Ecological Processes ◽  
Additional Information ◽  
Selective Pressures ◽  
Plant Life ◽  
Species Performance

Plant functional traits provide a valuable tool to improve our understanding of ecological processes at a range of scales. Previous handbooks on plant functional traits have highlighted the importance of standardising measurements of traits to improve our understanding of ecological and evolutionary processes. In open ecosystems (i.e. grasslands, savannas, open woodlands and shrublands), traits related to disturbance (e.g. herbivory, drought, and fire) play a central role in explaining species performance and distributions and are the focus of this handbook. We provide brief descriptions of 34 traits and list important environmental filters and their relevance, provide detailed sampling methodologies and outline potential pitfalls for each trait. We have grouped traits according to plant functional type (grasses, forbs and woody plants) and, because demographic stages may experience different selective pressures, we have separated traits according to the different plant life stages (seedlings saplings and adults). We have attempted to not include traits that have been covered in previous handbooks except for where updates or additional information was considered beneficial.

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