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Hotspots of Community Change: Temporal Dynamics Are Spatially Variable in Understory Plant Composition of a California Oak Woodland.

Spotswood EN, Bartolome JW, Allen-Diaz B - PLoS ONE (2015)

Bottom Line: Temporal dynamics are often assumed to be relatively static at the landscape scale, provided disturbance and climate are continuous.This study shows that local and landscape scale factors jointly influence temporal dynamics creating hotspots that are particularly responsive to climate and disturbance.Thus, adequate predictions of response to disturbance or to changing climate will only be achieved by considering how factors at multiple spatial scales influence community resilience and recovery.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America.

ABSTRACT
Community response to external drivers such climate and disturbance can lead to fluctuations in community composition, or to directional change. Temporal dynamics can be influenced by a combination of drivers operating at multiple spatial scales, including external landscape scale drivers, local abiotic conditions, and local species pools. We hypothesized that spatial variation in these factors can create heterogeneity in temporal dynamics within landscapes. We used understory plant species composition from an 11 year dataset from a California oak woodland to compare plots where disturbance was experimentally manipulated with the removal of livestock grazing and a prescribed burn. We quantified three properties of temporal variation: compositional change (reflecting the appearance and disappearance of species), temporal fluctuation, and directional change. Directional change was related most strongly to disturbance type, and was highest at plots where grazing was removed during the study. Temporal fluctuations, compositional change, and directional change were all related to intrinsic abiotic factors, suggesting that some locations are more responsive to external drivers than others. Temporal fluctuations and compositional change were linked to local functional composition, indicating that environmental filters can create subsets of the local species pool that do not respond in the same way to external drivers. Temporal dynamics are often assumed to be relatively static at the landscape scale, provided disturbance and climate are continuous. This study shows that local and landscape scale factors jointly influence temporal dynamics creating hotspots that are particularly responsive to climate and disturbance. Thus, adequate predictions of response to disturbance or to changing climate will only be achieved by considering how factors at multiple spatial scales influence community resilience and recovery.

No MeSH data available.


Related in: MedlinePlus

Functional composition, precipitation, and species richness.In the left column, changes in average grass, forb, perennial and annual composition across all study plots during the study period (in average percent cover) are represented as lines and bars represent deviations from the 20 year average in fall rainfall (mm) for each year during the study period. The right column shows the relationship between average perennials and forb composition and species richness. Points represent average cover or richness during the entire study period from 54 plots.
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pone.0133501.g002: Functional composition, precipitation, and species richness.In the left column, changes in average grass, forb, perennial and annual composition across all study plots during the study period (in average percent cover) are represented as lines and bars represent deviations from the 20 year average in fall rainfall (mm) for each year during the study period. The right column shows the relationship between average perennials and forb composition and species richness. Points represent average cover or richness during the entire study period from 54 plots.

Mentions: External driver variables were represented by treatment type (continuous grazing, grazing removal and burning). Abiotic factors included soil properties (clay (%), phosphorus, pH, C:N ratio) and environmental variables (aspect, topographic slope and position). Biotic variables that could reflect environmental filtering that limits the species pool at a site were represented using functional categories including grass, forb, perennial and annual composition. While these groupings represent only coarse functional categories, they are nonetheless highly relevant to temporal dynamics in California grasslands, where annual composition can fluctuate widely with interannual variation in precipitation [34], perennial composition tends to be more stable [23], and forbs are usually found at very low abundance, but often represent a large proportion of the species richness (Fig 2). Compositional variables were quantified using the species composition of each plot before disturbance treatments were applied, averaged over the pre-treatment period. Because functional composition variables were correlated with one another (especially grass and annual composition), we included only pre-treatment forb and perennial composition, which were not correlated. These two variables are highly negatively correlated with the absent variables and with species richness; high forb composition also indicates high species richness and low grass composition, and high perennial composition indicates relatively low annual composition (Fig 2).


Hotspots of Community Change: Temporal Dynamics Are Spatially Variable in Understory Plant Composition of a California Oak Woodland.

Spotswood EN, Bartolome JW, Allen-Diaz B - PLoS ONE (2015)

Functional composition, precipitation, and species richness.In the left column, changes in average grass, forb, perennial and annual composition across all study plots during the study period (in average percent cover) are represented as lines and bars represent deviations from the 20 year average in fall rainfall (mm) for each year during the study period. The right column shows the relationship between average perennials and forb composition and species richness. Points represent average cover or richness during the entire study period from 54 plots.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519272&req=5

pone.0133501.g002: Functional composition, precipitation, and species richness.In the left column, changes in average grass, forb, perennial and annual composition across all study plots during the study period (in average percent cover) are represented as lines and bars represent deviations from the 20 year average in fall rainfall (mm) for each year during the study period. The right column shows the relationship between average perennials and forb composition and species richness. Points represent average cover or richness during the entire study period from 54 plots.
Mentions: External driver variables were represented by treatment type (continuous grazing, grazing removal and burning). Abiotic factors included soil properties (clay (%), phosphorus, pH, C:N ratio) and environmental variables (aspect, topographic slope and position). Biotic variables that could reflect environmental filtering that limits the species pool at a site were represented using functional categories including grass, forb, perennial and annual composition. While these groupings represent only coarse functional categories, they are nonetheless highly relevant to temporal dynamics in California grasslands, where annual composition can fluctuate widely with interannual variation in precipitation [34], perennial composition tends to be more stable [23], and forbs are usually found at very low abundance, but often represent a large proportion of the species richness (Fig 2). Compositional variables were quantified using the species composition of each plot before disturbance treatments were applied, averaged over the pre-treatment period. Because functional composition variables were correlated with one another (especially grass and annual composition), we included only pre-treatment forb and perennial composition, which were not correlated. These two variables are highly negatively correlated with the absent variables and with species richness; high forb composition also indicates high species richness and low grass composition, and high perennial composition indicates relatively low annual composition (Fig 2).

Bottom Line: Temporal dynamics are often assumed to be relatively static at the landscape scale, provided disturbance and climate are continuous.This study shows that local and landscape scale factors jointly influence temporal dynamics creating hotspots that are particularly responsive to climate and disturbance.Thus, adequate predictions of response to disturbance or to changing climate will only be achieved by considering how factors at multiple spatial scales influence community resilience and recovery.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America.

ABSTRACT
Community response to external drivers such climate and disturbance can lead to fluctuations in community composition, or to directional change. Temporal dynamics can be influenced by a combination of drivers operating at multiple spatial scales, including external landscape scale drivers, local abiotic conditions, and local species pools. We hypothesized that spatial variation in these factors can create heterogeneity in temporal dynamics within landscapes. We used understory plant species composition from an 11 year dataset from a California oak woodland to compare plots where disturbance was experimentally manipulated with the removal of livestock grazing and a prescribed burn. We quantified three properties of temporal variation: compositional change (reflecting the appearance and disappearance of species), temporal fluctuation, and directional change. Directional change was related most strongly to disturbance type, and was highest at plots where grazing was removed during the study. Temporal fluctuations, compositional change, and directional change were all related to intrinsic abiotic factors, suggesting that some locations are more responsive to external drivers than others. Temporal fluctuations and compositional change were linked to local functional composition, indicating that environmental filters can create subsets of the local species pool that do not respond in the same way to external drivers. Temporal dynamics are often assumed to be relatively static at the landscape scale, provided disturbance and climate are continuous. This study shows that local and landscape scale factors jointly influence temporal dynamics creating hotspots that are particularly responsive to climate and disturbance. Thus, adequate predictions of response to disturbance or to changing climate will only be achieved by considering how factors at multiple spatial scales influence community resilience and recovery.

No MeSH data available.


Related in: MedlinePlus