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Title: Variance reflects resilience to disturbance along a stress gradient: Experimental evidence from coastal marshes
Abstract
Quantifying ecosystem resilience to disturbance is important for understanding the effects of disturbances on ecosystems, especially in an era of rapid global change. However, there are few studies that have used standardized experimental disturbances to compare resilience patterns across abiotic gradients in real‐world ecosystems. Theoretical studies have suggested that increased return times are associated with increasing variance during recovery from disturbance. However, this notion has rarely been explicitly tested in field, in part due to the challenges involved in obtaining long‐term experimental data. In this study, we examined resilience to disturbance of 12 coastal marsh sites (five low‐salinity and seven polyhaline [=salt] marshes) along a salinity gradient in Georgia, USA. We found that recovery times after experimental disturbance ranged from 7 to >127 months, and differed among response variables (vegetation height, cover and composition). Recovery rates decreased along the stress gradient of increasing salinity, presumably due to stress reducing plant vigor, but only when low‐salinity and polyhaline sites were analyzed separately, indicating a strong role for traits of dominant plant species. The coefficient of variation of vegetation cover and height in control plots did not vary with salinity. In disturbed plots, however, the coefficient of variation (CV) was consistently elevated during the recovery period and increased with salinity. Moreover, higher CV values during recovery were correlated with slower recovery rates. Our results deepen our understanding of resilience to disturbance in natural ecosystems, and point to novel ways that variance can be used either to infer recent disturbance, or, if measured in areas with a known disturbance history, to predict recovery patterns.
De Battisti, Davide; Angelini, Christine; Joyce, Matthew; Crotty, Sinead; Fairchild, Tom P.; Fischman, Hallie S.; Griffin, John N.(
, Journal of Vegetation Science)
AbstractAims
Latitudinal gradients in plant communities are well studied, yet how these fundamental ecological patterns influence ecosystem recovery after extreme weather events remains largely unknown. In coastal foredunes, we investigated how the cover of a key dune‐building grass (Uniola paniculata), vegetation diversity and vegetation cover vary along a short latitudinal gradient during recovery from hurricane disturbance.
Location
Southeastern USA.
Methods
We surveyed 24 sites, from central Florida to north Georgia (>400 km), four times over 18 months. General linear mixed‐effect models were used to unravel patterns of vegetation responses across latitude.
Results
Vegetation properties showed countervailing patterns across the latitudinal gradient. While vegetation richness, functional diversity and total cover generally declined,Uniolacover increased with increasing latitude. Further, the latitude–richness relationship strengthened while the latitude–functional diversity relationship was invariant with increasing time since the hurricane disturbance. Meanwhile, the latitude–Uniolaassociation was seasonally dependent and strongest in the summer. Latitude also influenced diversity–cover relationships: vegetation cover was positively related to species richness at lower latitudes, while it was positively associated with functional diversity only at northern sites. We found no relationship between species richness or functional diversity and increases in cover between time steps; however, recruitment of new species and functional groups was associated with increases in vegetation cover between time steps at northern sites.
Conclusions
Our study highlights the temporal dynamism and contrasting patterns along latitudinal gradients exhibited by key engineering species and overall plant diversity in foredunes — a crucial line of coastal protection — exposed to hurricane disturbances. These results suggest a need for greater integration of latitudinal and diversity effects into our understanding of coastal dune resilience. They also highlight the potential benefits of enhancing dune plant biodiversity, particularly in areas where the dune‐building grasses that are classically employed in restoration (e.g.,Uniola) are unfavoured, to accelerate the re‐establishment of well‐vegetated dunes.
Pilon, Natashi A. L.; Cava, Mário G. B.; Hoffmann, William A.; Abreu, Rodolfo C. R.; Fidelis, Alessandra; Durigan, Giselda; Staver, ed., Carla(
, Journal of Ecology)
Abstract
Disentangling species strategies that confer resilience to natural disturbances is key to conserving and restoring savanna ecosystems. Fire is a recurrent disturbance in savannas, and savanna vegetation is highly adapted to and often dependent on fire. However, although the woody component of tropical savannas is well studied, we still do not understand how ground‐layer plant communities respond to fire, limiting conservation and management actions.
We investigated the effects of prescribed fire on community structure and composition, and evaluated which traits are involved in plant community regeneration after fire in the cerrado ground layer. We assessed traits related to species persistence and colonization capacity after fire, including resprouter type, underground structure, fire‐induced flowering, regeneration strategy and growth form. We searched for functional groups related to response to fire, to shed light on the main strategies of post‐fire recovery among species in the ground layer.
Fire changed ground‐layer community structure and composition in the short term, leading to greater plant species richness, population densities and increasing bare soil, compared with unburned communities. Eight months after fire, species abundance did not differ from pre‐disturbance values for 86% of the species, demonstrating the resilience of this layer to fire. Only one ruderal species was disadvantaged by fire and 13% of the species benefited. Rapid recovery of soil cover by native vegetation in burned areas was driven by species with high capacity to resprout and spread vegetatively. Recovery of the savanna ground‐layer community, as a whole, resulted from a combination of different species traits. We summarized these traits into five large groups, encompassing key strategies involved in ground‐layer regeneration after fire.
Synthesis. Fire dramatically changes the ground layer of savanna vegetation in the short term, but the system is highly resilient, quickly recovering the pre‐fire state. Recovery involves different strategies, which we categorized into five functional groups of plant species:grasses,seeders,bloomers,undergroundersandresprouters. Knowledge of these diverse strategies should be used as a tool to assess conservation and restoration status of fire‐resilient ecosystems in the cerrado.
Baur, Lauren; Collins, Scott; Muldavin, Esteban; Rudgers, Jennifer A; Pockman, William T.(
, Environmental Data Initiative)
This dataset includes estimated plant aboveground live biomass data measured in 1 m x 1 m quadrats at several sites and experiments under the Sevilleta LTER program. Quadrat locations span four distinct ecosystems and their ecotones: creosotebush dominated Chihuahuan Desert shrubland (est. winter 1999), black grama-dominated Chihuahuan Desert grassland (est. winter 1999), blue grama-dominated Plains grassland (est. winter 2002), and pinon-juniper woodland (est. winter 2003). Data on plant cover and height for each plant species are collected per individual plant or patch (for clonal plants) within 1 m x 1 m quadrats. These data inform population dynamics of foundational and rare plant species. Biomass is estimated using plant allometries from non-destructive measurements of plant cover and height, and can be used to calculate net primary production (NPP), a fundamental ecosystem variable that quantifies rates of carbon consumption and fixation. Estimates of plant species cover, total plant biomass, or NPP can inform understanding of biodiversity, species composition, and energy flow at the community scale of biological organization, as well as spatial and temporal responses of plants to a range of ecological processes and direct experimental manipulations. The cover and height of individual plants or patches are sampled twice yearly (spring and fall) in permanent 1m x 1m plots within each site or experiment. This dataset includes core site monitoring data (CORE, GRIDS, ISOWEB, TOWER), observations in response to wildfire (BURN), and experimental treatments of extreme drought and delayed monsoon rainfall (EDGE), physical disturbance to biological soil crusts on the soil surface (CRUST), interannual variability in precipitation (MEANVAR), intra-annual variability via additions of monsoon rainfall (MRME), additions of nitrogen as ammonium nitrate (FERTILIZER), additions of nitrogen x phosphorus x potassium (NutNet), and interacting effects of nighttime warming, nitrogen addition, and El Niño winter rainfall (WENNDEx). To build allometric equations that relate biomass to plant cover or volume, the dataset "SEV-LTER quadrat plant cover and height data all sites and experiments" is used with a separate dataset of selectively harvested plant species "SEV-LTER Plant species mass data for allometry." Together, these datasets produced “SEV-LTER quadrat plant species biomass all sites and experiments” using the scripts posted with the allometry dataset. Data from the CORE sites in this dataset were designated as NA-US-011 in the Global Index of Vegetation-Plot Databases (GIVD). Data from the TOWER sites in this dataset are linked to Ameriflux sites: ameriflux.lbl.gov/doi/AmeriFlux/US-Seg and ameriflux.lbl.gov/sites/siteinfo/US-Ses.
Baur, Lauren; Collins, Scott; Muldavin, Esteban; Rudgers, Jennifer A; Pockman, William T.(
, Environmental Data Initiative)
This dataset includes plant species cover and height data measured in 1 m x 1 m quadrats at several sites and experiments under the Sevilleta LTER program. Quadrat locations span four distinct ecosystems and their ecotones: creosotebush dominated Chihuahuan Desert shrubland (est. winter 1999), black grama-dominated Chihuahuan Desert grassland (est. winter 1999), blue grama-dominated Plains grassland (est. winter 2002), and pinon-juniper woodland (est. winter 2003). Data on plant cover and height for each plant species are collected per individual plant or patch (for clonal plants) within 1 m x 1 m quadrats. These data inform population dynamics of foundational and rare plant species. In addition, using plant allometries, these non-destructive measurements of plant cover and height can be used to calculate net primary production (NPP), a fundamental ecosystem variable that quantifies rates of carbon consumption and fixation. Estimates of plant species cover, total plant biomass, or NPP can inform understanding of biodiversity, species composition, and energy flow at the community scale of biological organization, as well as spatial and temporal responses of plants to a range of ecological processes and direct experimental manipulations. The cover and height of individual plants or patches are sampled twice yearly (spring and fall) in permanent 1m x 1m plots within each site or experiment. This dataset includes core site monitoring data (CORE, GRIDS, ISOWEB, TOWER), observations in response to wildfire (BURN), and experimental treatments of extreme drought and delayed monsoon rainfall (EDGE), physical disturbance to biological soil crusts on the soil surface (CRUST), interannual variability in precipitation (MEANVAR), intra-annual variability via additions of monsoon rainfall (MRME), additions of nitrogen as ammonium nitrate (FERTILIZER), additions of nitrogen x phosphorus x potassium (NutNet), and interacting effects of nighttime warming, nitrogen addition, and El Niño winter rainfall (WENNDEx). To build allometric equations that relate biomass to plant cover or volume, a separate dataset of selectively harvested plant species is provided in "SEV-LTER Plant species mass data for allometry." Together, these datasets produce “SEV-LTER Plant biomass all sites and experiments” using the scripts posted with that dataset. Data from the CORE sites in this dataset were designated as NA-US-011 in the Global Index of Vegetation-Plot Databases (GIVD). Data from the TOWER sites in this dataset are linked to Ameriflux sites: ameriflux.lbl.gov/doi/AmeriFlux/US-Seg and ameriflux.lbl.gov/sites/siteinfo/US-Ses.
Abella, Scott R.; Gentilcore, Dominic M.; Chiquoine, Lindsay P.(
, Ecological Monographs)
Abstract
Improving models of community change is a fundamental goal in ecology and has renewed importance during global change and increasing human disturbance of the biosphere. Using the Mojave Desert (southwestern United States) as a model system, invaded by nonnative plants and subject to wildfire disturbances, we examined models of resilience, alternative stable states, and convergent‐divergent trajectories for 36 yr of plant community change after 31 wildfires in communities dominated by the native shrubsLarrea tridentataorColeogyne ramosissima. Perennial species richness on average was fully resilient within 23 yr after disturbance in both community types. Perennial cover was fully resilient within 25 yr in theLarreacommunity, but recovery was projected to require 52 yr in theColeogynecommunity. Species composition shifts were persistent, and in theColeogynecommunity, the projected compositional recovery time of 550 yr and increasing resembled a deflected trajectory toward potential alternative states. Disturbed sites contained a perennial species composition of predominately short‐statured forbs, subshrubs, and grasses, contrasting with the larger‐statured shrub and tree structure of undisturbed sites. Auxiliary data sets characterizing species recruitment, annual plants including nonnative grasses, biocrust communities, and soils showed persistent differences between disturbed and undisturbed sites consistent with positive feedbacks potentially contributing to alternative stable states. Resprouting produced limited resilience for the large shrubsL. tridentataandYuccaspp. important to population persistence but did not forestall long‐term reduced abundance of the species. The nonnative annual grassBromus rubensincreased on disturbed sites over time, suggesting persistently abundant nonnative plant fuels and reburn potential. Biocrust cover on disturbed sites was half and species richness a third of amounts on undisturbed sites. Soil nitrogen was 30% greater on disturbed sites and no significant trend was evident for it to decline on even the oldest burns. Disturbed desert plant communities simultaneously supported all three models of resilience, alternative stable states, and convergent‐divergent trajectories among community measures (e.g., species richness, composition), timeframes since disturbance, and spatial resolutions. Accommodating expression within ecosystems of multiple models, including those opposing each other, may help broaden theoretical models of ecosystem change.
Wang, Yinhua, Guo, Hongyu, Alber, Merryl, and Pennings, Steven C. Variance reflects resilience to disturbance along a stress gradient: Experimental evidence from coastal marshes. Ecology . Web. doi:10.1002/ecy.4241.
Wang, Yinhua, Guo, Hongyu, Alber, Merryl, & Pennings, Steven C. Variance reflects resilience to disturbance along a stress gradient: Experimental evidence from coastal marshes. Ecology, (). https://doi.org/10.1002/ecy.4241
Wang, Yinhua, Guo, Hongyu, Alber, Merryl, and Pennings, Steven C.
"Variance reflects resilience to disturbance along a stress gradient: Experimental evidence from coastal marshes". Ecology (). Country unknown/Code not available: Wiley Blackwell (John Wiley & Sons). https://doi.org/10.1002/ecy.4241.https://par.nsf.gov/biblio/10487669.
@article{osti_10487669,
place = {Country unknown/Code not available},
title = {Variance reflects resilience to disturbance along a stress gradient: Experimental evidence from coastal marshes},
url = {https://par.nsf.gov/biblio/10487669},
DOI = {10.1002/ecy.4241},
abstractNote = {Abstract Quantifying ecosystem resilience to disturbance is important for understanding the effects of disturbances on ecosystems, especially in an era of rapid global change. However, there are few studies that have used standardized experimental disturbances to compare resilience patterns across abiotic gradients in real‐world ecosystems. Theoretical studies have suggested that increased return times are associated with increasing variance during recovery from disturbance. However, this notion has rarely been explicitly tested in field, in part due to the challenges involved in obtaining long‐term experimental data. In this study, we examined resilience to disturbance of 12 coastal marsh sites (five low‐salinity and seven polyhaline [=salt] marshes) along a salinity gradient in Georgia, USA. We found that recovery times after experimental disturbance ranged from 7 to >127 months, and differed among response variables (vegetation height, cover and composition). Recovery rates decreased along the stress gradient of increasing salinity, presumably due to stress reducing plant vigor, but only when low‐salinity and polyhaline sites were analyzed separately, indicating a strong role for traits of dominant plant species. The coefficient of variation of vegetation cover and height in control plots did not vary with salinity. In disturbed plots, however, the coefficient of variation (CV) was consistently elevated during the recovery period and increased with salinity. Moreover, higher CV values during recovery were correlated with slower recovery rates. Our results deepen our understanding of resilience to disturbance in natural ecosystems, and point to novel ways that variance can be used either to infer recent disturbance, or, if measured in areas with a known disturbance history, to predict recovery patterns.},
journal = {Ecology},
publisher = {Wiley Blackwell (John Wiley & Sons)},
author = {Wang, Yinhua and Guo, Hongyu and Alber, Merryl and Pennings, Steven C.},
}
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