Experimental dispersal reveals characteristic scales of biodiversity in a natural landscape

Ecological theory posits that dispersal among habitat patches links local communities and is a key “regional” process that maintains biological diversity. However, manipulations required to experimentally test regional processes are infeasible for most systems, and thus more work is needed to detect the scales at which regional processes manifest and their overall effect on diversity. In a Californian grassland, a hotspot for global biodiversity, we used a seed vacuum to increase dispersal at spatial scales varying from 1 m to 10 km while maintaining a realistic spatial structure of species pools and environmental conditions. We found that dispersal limitation has a profound influence on diversity; species richness increased with the spatial scale of seed mixing, doubling in plots that received seed from large (≥5 km) compared with small (≤5 m) scales. This increase in diversity corresponded to an increase in how well species distributions were explained by environmental conditions, from modest at small scales (R2= 0.34) to strong at large scales (R2= 0.52). Responses to the spatial scale of seed mixing were nonlinear, with no differences below 5 m or above 5 km. Nonlinearities were explained by homogeneity of environmental conditions below 5 m and by a lack of additional variation in the species pool above 5 km. Our approach of manipulating natural communities at different spatial scales reveals (i) nonlinear transitions in the importance of environmental sorting and dispersal, and (ii) the negative effects of dispersal limitation on local diversity, consistent with previous research suggesting that large numbers of species are headed toward regional extinction.

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Beyond a single patch: local and regional processes explain diversity patterns in a seagrass epifaunal metacommunity

10.1101/482406 ◽

2018 ◽

Author(s):

Keila A Stark ◽

Patrick L Thompson ◽

Jennifer Yakimishyn ◽

Lynn Lee ◽

Emily M Adamczyk ◽

...

Keyword(s):

Environmental Conditions ◽

Spatial Scales ◽

Interspecific Interactions ◽

Ecosystem Functions ◽

Seagrass Meadows ◽

High Dispersal ◽

Invertebrate Abundance ◽

Local And Regional Processes ◽

Abundance And Distribution ◽

Regional Processes

AbstractEcological communities are jointly structured by dispersal, density-independent responses to environmental conditions and density-dependent biotic interactions. Metacommunity ecology provides a framework for understanding how these processes combine to determine community composition among local sites that are regionally connected through dispersal. In 17 temperate seagrass meadows along the British Columbia coast, we tested the hypothesis that eelgrass (Zostera marinaL.) epifaunal invertebrate assemblages are influenced by local environmental conditions, but that high dispersal rates at larger spatial scales dampen effects of environmental differences. We used hierarchical joint species distribution modelling to understand the contribution of environmental conditions, spatial distance between meadows, and species co-occurrences to epifaunal invertebrate abundance and distribution across the region. We found that patterns of taxonomic compositional similarity among meadows were inconsistent with dispersal limitation and meadows in the same region were often no more similar to each other than meadows over 1000 km away. Abiotic environmental conditions (temperature, dissolved oxygen) explained a small fraction of variation in taxonomic abundances patterns across the region. We found novel co-occurrence patterns among taxa that could not be explained by shared responses to environmental gradients, suggesting the possibility that interspecific interactions influence seagrass invertebrate abundance and distribution. Our results add to mounting evidence that suggests that the biodiversity and ecosystem functions provided by seagrass meadows reflect ecological processes occurring both within meadows and across seascapes, and suggest that management of eelgrass habitat for biodiversity may be most effective when both local and regional processes are considered.

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Beyond a single patch: local and regional processes explain diversity patterns in a seagrass epifaunal metacommunity

Marine Ecology Progress Series ◽

10.3354/meps13527 ◽

2020 ◽

Vol 655 ◽

pp. 91-106

Author(s):

KA Stark ◽

PL Thompson ◽

J Yakimishyn ◽

L Lee ◽

EM Adamczyk ◽

...

Keyword(s):

Environmental Conditions ◽

Spatial Scales ◽

Interspecific Interactions ◽

Ecosystem Functions ◽

Seagrass Meadows ◽

High Dispersal ◽

Invertebrate Abundance ◽

Local And Regional Processes ◽

Abundance And Distribution ◽

Regional Processes

Ecological communities are jointly structured by dispersal, density-independent responses to environmental conditions, and density-dependent biotic interactions. Metacommunity ecology provides a framework for understanding how these processes combine to determine community seagrass meadows along the British Columbia coast. We tested the hypothesis that eelgrass Zostera marina L. epifaunal invertebrate assemblages are influenced by local environmental conditions but that high dispersal rates at larger spatial scales dampen the effects of environmental differences. We used hierarchical joint species distribution modelling to understand the contribution of environmental conditions, spatial distance between meadows, and species co-occurrences to epifaunal invertebrate abundance and distribution across the region. We found that patterns of taxonomic compositional similarity among meadows were inconsistent with dispersal limitation, and meadows in the same region were often no more similar to each other than meadows over 1000 km away. Abiotic environmental conditions (temperature, dissolved oxygen) explained a small fraction of variation in taxonomic abundance patterns across the region. We found novel co-occurrence patterns among taxa that could not be explained by shared responses to environmental gradients, suggesting the possibility that interspecific interactions influence seagrass invertebrate abundance and distribution. Our results suggest that biodiversity and ecosystem functions provided by seagrass meadows reflect ecological processes occurring both within meadows and across seascapes and that management of eelgrass habitat for biodiversity may be most effective when both local and regional processes are considered.

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Effects of spatial scale and choice of statistical model (linear versus tree-based) on determining species–habitat relationships

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2011-0505 ◽

2012 ◽

Vol 69 (12) ◽

pp. 2095-2111 ◽

Cited By ~ 7

Author(s):

Sapna Sharma ◽

Pierre Legendre ◽

Daniel Boisclair ◽

Stéphane Gauthier

Keyword(s):

Spatial Scale ◽

Habitat Quality ◽

Spatial Data ◽

Environmental Conditions ◽

Habitat Structure ◽

Spatial Scales ◽

Fish Habitat ◽

Habitat Associations ◽

Environmental Data ◽

Positioning Systems

The choice of spatial scale and modelling technique used to capture species–habitat relationships needs to be considered when ascertaining environmental determinants of habitat quality for species and communities. Fish densities and environmental data were collected at three Laurentian lakes using underwater surveys by four snorkelers collecting fine spatial data acquired through geographic positioning systems. At both fine (20 m) and broad (100 m) spatial scales, tree-based approaches, which incorporated both linear and nonlinear relationships, explained more variation than their linear counterparts. At the finest spatial scale considered (20 m), local environmental conditions, such as habitat structure and heterogeneity, were important determinants of fish habitat selection. At the broadest spatial scale considered (100 m), fish tended to select habitat based on both local environmental features and riparian development. Moran’s eigenvector maps further revealed that fish–habitat associations were operating at broader spatial scales than the predefined analytical units, which can be partially attributed to the spatial structure of environmental conditions acting at spatial scales greater than 100 m. This study highlights the importance of evaluating statistical approaches at different spatial scales to identify key determinants of habitat quality for species, ultimately to assess the effects of perturbations on ecosystems.

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Selection imposed by local environmental conditions drives differences in microbial community composition across geographically distinct groundwater aquifers

FEMS Microbiology Ecology ◽

10.1093/femsec/fiz160 ◽

2019 ◽

Vol 95 (11) ◽

Cited By ~ 3

Author(s):

Lucas Fillinger ◽

Katrin Hug ◽

Christian Griebler

Keyword(s):

Microbial Community ◽

Community Composition ◽

Environmental Conditions ◽

Spatial Scales ◽

Variation Partitioning ◽

Microbial Community Composition ◽

Dispersal Limitation ◽

Distribution Patterns ◽

Groundwater Aquifers ◽

Specific Factors

ABSTRACT Several studies have analyzed biogeographic distribution patterns of microbial communities across broad spatial scales. However, it is often unclear to what extent differences in community composition across different regions are caused by dispersal limitation or selection, and if selection is caused by local environmental conditions alone or additional broad-scale region-specific factors. This is especially true for groundwater environments, which have been understudied in this context relative to other non-subsurface habitats. Here, we analyzed microbial community composition based on exact 16S rRNA amplicon sequence variants (ASVs) from four geographically separated aquifers located in different regions along a latitudinal transect of ∼700 km across Germany. Using a combination of variation partitioning and ecological null models revealed that differences in microbial community composition were mainly the product of selection imposed by local environmental conditions and to a smaller but still significant extent dispersal limitation and drift across regions. Only ∼23% of the total variation in microbial community composition remained unexplained, possibly due to underestimated effects of dispersal limitation among local communities within regions and temporal drift. No evidence was found for selection due to region-specific factors independent of local environmental conditions.

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8-Day and Daily Maximum and Minimum Air Temperature Estimation via Machine Learning Method on a Climate Zone to Global Scale

Remote Sensing ◽

10.3390/rs13122355 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2355

Author(s):

Linglin Zeng ◽

Yuchao Hu ◽

Rui Wang ◽

Xiang Zhang ◽

Guozhang Peng ◽

...

Keyword(s):

Spatial Scale ◽

Air Temperature ◽

Spatial Scales ◽

Model Performance ◽

Global Scale ◽

Scale Model ◽

Validation Dataset ◽

Daily Maximum ◽

Climate Zone ◽

Temporal And Spatial

Air temperature (Ta) is a required input in a wide range of applications, e.g., agriculture. Land Surface Temperature (LST) products from Moderate Resolution Imaging Spectroradiometer (MODIS) are widely used to estimate Ta. Previous studies of these products in Ta estimation, however, were generally applied in small areas and with a small number of meteorological stations. This study designed both temporal and spatial experiments to estimate 8-day and daily maximum and minimum Ta (Tmax and Tmin) on three spatial scales: climate zone, continental and global scales from 2009 to 2018, using the Random Forest (RF) method based on MODIS LST products and other auxiliary data. Factors contributing to the relation between LST and Ta were determined based on physical models and equations. Temporal and spatial experiments were defined by the rules of dividing the training and validation datasets for the RF method, in which the stations selected in the training dataset were all included or not in the validation dataset. The RF model was first trained and validated on each spatial scale, respectively. On a global scale, model accuracy with a determination coefficient (R2) > 0.96 and root mean square error (RMSE) < 1.96 °C and R2 > 0.95 and RMSE < 2.55 °C was achieved for 8-day and daily Ta estimations, respectively, in both temporal and spatial experiments. Then the model was trained and cross-validated on each spatial scale. The results showed that the data size and station distribution of the study area were the main factors influencing the model performance at different spatial scales. Finally, the spatial patterns of the model performance and variable importance were analyzed. Both daytime and nighttime LST had a significant contribution in the 8-day Tmax estimation on all the three spatial scales; while their contribution in daily Tmax estimation varied over different continents or climate zones. This study was expected to improve our understanding of Ta estimation in terms of accuracy variations and influencing variables on different spatial and temporal scales. The future work mainly includes identifying underlying mechanisms of estimation errors and the uncertainty sources of Ta estimation from a local to a global scale.

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Non-Standard Discrete RothC Models for Soil Carbon Dynamics

Axioms ◽

10.3390/axioms10020056 ◽

2021 ◽

Vol 10 (2) ◽

pp. 56

Author(s):

Fasma Diele ◽

Carmela Marangi ◽

Angela Martiradonna

Keyword(s):

Soil Carbon ◽

Land Degradation ◽

Biological Diversity ◽

Negative Effects ◽

Land Use Patterns ◽

Use Patterns ◽

Soil Carbon Content ◽

Rothc Model ◽

Key Indicators

Soil Organic Carbon (SOC) is one of the key indicators of land degradation. SOC positively affects soil functions with regard to habitats, biological diversity and soil fertility; therefore, a reduction in the SOC stock of soil results in degradation, and it may also have potential negative effects on soil-derived ecosystem services. Dynamical models, such as the Rothamsted Carbon (RothC) model, may predict the long-term behaviour of soil carbon content and may suggest optimal land use patterns suitable for the achievement of land degradation neutrality as measured in terms of the SOC indicator. In this paper, we compared continuous and discrete versions of the RothC model, especially to achieve long-term solutions. The original discrete formulation of the RothC model was then compared with a novel non-standard integrator that represents an alternative to the exponential Rosenbrock–Euler approach in the literature.

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Protected Areas: offering security to whom, when and where?

Environmental Conservation ◽

10.1017/s0376892915000375 ◽

2016 ◽

Vol 43 (2) ◽

pp. 172-180 ◽

Cited By ~ 7

Author(s):

ALICE B. KELLY ◽

A. CLARE GUPTA

Keyword(s):

Protected Areas ◽

Environmental Conditions ◽

Protected Area ◽

Spatial Scales ◽

Local Population ◽

Well Being ◽

Economic Context ◽

Term Management ◽

Over Time

SUMMARYThis study considers the issue of security in the context of protected areas in Cameroon and Botswana. Though the literature on issues of security and well-being in relation to protected areas is extensive, there has been less discussion of how and in what ways these impacts and relationships can change over time, vary with space and differ across spatial scales. Looking at two very different historical trajectories, this study considers the heterogeneity of the security landscapes created by Waza and Chobe protected areas over time and space. This study finds that conservation measures that various subsets of the local population once considered to be ‘bad’ (e.g. violent, exclusionary protected area creation) may be construed as ‘good’ at different historical moments and geographical areas. Similarly, complacency or resignation to the presence of a park can be reversed by changing environmental conditions. Changes in the ways security (material and otherwise) has fluctuated within these two protected areas has implications for the long-term management and funding strategies of newly created and already existing protected areas today. This study suggests that parks must be adaptively managed not only for changing ecological conditions, but also for shifts in a protected area's social, political and economic context.

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Fungi and diseases — natural components of healthy forestsThis article is one of a collection of papers based on a presentation from the Stem and Shoot Fungal Pathogens and Parasitic Plants: the Values of Biological Diversity session of the XXII International Union of Forestry Research Organization World Congress meeting held in Brisbane, Queensland, Australia, in 2005.

Botany ◽

10.1139/b08-090 ◽

2009 ◽

Vol 87 (1) ◽

pp. 22-25 ◽

Cited By ~ 20

Author(s):

M. E. Ostry ◽

G. Laflamme

Keyword(s):

Fungal Pathogens ◽

Biological Diversity ◽

Forest Health ◽

Disease Outbreaks ◽

Ecological Interactions ◽

Negative Effects ◽

Land Owners ◽

Negative Impacts ◽

The Many ◽

Native Fungi

Forest health is described and perceived in different ways by the general public, land owners, managers, politicians, and scientists, depending on their values and objectives. Native tree pathogens and diseases are often associated with negative impacts even though damage is limited or not widespread. Too often, the concepts of tree health and forest health are used interchangeably and are not related to scale. Similar to fire, occurrences of disease outbreaks focus on the negative effects. However, native pathogens often exist in equilibrium with natural forest communities so their critical ecological roles are not easily discernible. Examined holistically, native fungi and diseases, dead and dying trees, and the many complex ecological interactions among them provide valuable benefits that ultimately contribute to sustainable, healthy forest ecosystems.

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A reinterpretation of Scottish ‘hummocky moraine’ and its significance for the deglaciation of the Scottish Highlands during the Younger Dryas or Loch Lomond Stadial

Geological Magazine ◽

10.1017/s0016756800019993 ◽

1993 ◽

Vol 130 (3) ◽

pp. 301-318 ◽

Cited By ~ 85

Author(s):

Matthew R. Bennett ◽

Geoffrey S. Boulton

Keyword(s):

Environmental Conditions ◽

Field Survey ◽

Spatial Scales ◽

Younger Dryas ◽

North West ◽

Scottish Highlands ◽

Ice Cap ◽

The North ◽

Loch Lomond

AbstractThe aim of this paper is to demonstrate that much of the ‘hummocky moraine’ present within the northern part of the LochLomond Readvance ice cap formerly situated in the North West Scottish Highlands may be interpreted as suites of ice-front moraines deposited during active decay. These landforms can be used to reconstruct ice cap decay, whichleads to important insights into the shrinking form of the ice cap and associated environmental conditions. Evidence has been collected from 10803 airphotographs and from detailed field survey. It is presented at three spatial scales.

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Endoparasitism in colonial hosts: patterns and processes

Parasitology ◽

10.1017/s0031182007002259 ◽

2007 ◽

Vol 134 (6) ◽

pp. 841-852 ◽

Cited By ~ 26

Author(s):

S. L. L. HILL ◽

B. OKAMURA

Keyword(s):

Vertical Transmission ◽

Environmental Conditions ◽

Negative Effects ◽

Temporal Sampling ◽

Colony Fission ◽

High Prevalence ◽

Novel Host ◽

Patterns And Processes ◽

Host Parasite ◽

Lack Of Knowledge

SUMMARYThis study begins to redress our lack of knowledge of the interactions between colonial hosts and their parasites by focusing on a novel host-parasite system. Investigations of freshwater bryozoan populations revealed that infection by myxozoan parasites is widespread. Covert infections were detected in all 5 populations studied and were often at high prevalence while overt infections were observed in only 1. Infections were persistent in populations subject to temporal sampling. Negative effects of infection were identified but virulence was low. Infection did not induce mortality in the environmental conditions studied. However, the production of statoblasts (dormant propagules) was greatly reduced in bryozoans with overt infections in comparison to uninfected bryozoans. Overtly-infected bryozoans also grew more slowly and had low fission rates relative to colonies lacking overt infection. Bryozoans with covert infections were smaller than uninfected bryozoans. High levels of vertical transmission were achieved through colony fission and the infection of statoblasts. Increased fission rates may be a strategy for hosts to escape from parasites but the parasite can also exploit the fragmentation of colonial hosts to gain vertical transmission and dispersal. Our study provides evidence that opportunities and constraints for host-parasite co-evolution can be highly dependent on organismal body plans and that low virulence may be associated with exploitation of colonial hosts by endoparasites.

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