Testing for Thresholds in a Semiarid Grassland: The Influence of Prairie Dogs and Plague

Augustine, David J.; Derner, Justin D.; Detling, James K.

doi:10.2111/rem-d-14-00032.1

Cited by 19 publications

(22 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar results have been obtained in yeast cultures (Drake and Griffen ) and grasslands (Augustine et al. , Ratajczak et al. ), but more work is needed to determine the generality of these results and compare them to other proposed forecasting tools.…”

Section: Duration Effects In Generalsupporting

confidence: 76%

The interactive effects of press/pulse intensity and duration on regime shifts at multiple scales

Ratajczak

D’Odorico

Collins

et al. 2017

Ecological Monographs

View full text Add to dashboard Cite

Abstract. Regime shifts are difficult-to-reverse transitions that occur when an ecosystem reorganizes around a new set of self-reinforcing feedbacks. Regime shifts are predicted to occur when the intensity of some exogenous driver variable, such as temperature, annual harvest rate, or nutrient addition rate, gradually approaches and crosses a threshold value, initiating a transition to an alternative state. However, many driver variables now change rapidly as presses or pulses, not gradually, requiring new conceptual frameworks for understanding and predicting regime shifts. We argue that identifying and controlling regime shifts in response to presses and pulses will require a greater focus on the duration, not just the intensity, of changes in driver variables. In ecosystems with slower dynamics, transitions to an alternative state can take years to decades and as a result, a driver press with an intensity capable of resulting in a regime shift over long time spans may fail to cause a regime shift when applied for shorter durations. We illustrate these ideas using simulations of local-scale alternative stable state models and preliminary evidence from long-term grazing and eutrophication experiments. The simulations also suggest that small changes in the duration of driver presses or pulses can determine whether an ecosystem recovers to its original state. These insights may extend to larger scales. In spatially extended simulations that included patchiness, spatial heterogeneity, and spatial connectivity, all patches recovered to their original state after shorter presses. However, once press duration exceeded a threshold, growing proportions of the landscape shifted to an alternative state as press duration increased. We observed similar patchy transitions in a catchment-scale experiment that reinstated frequent fires approximately halfway through a regime shift from grassland to shrubland, initiated by fire suppression. In both the local-and larger-scale models, the threshold duration needed to elicit regime shifts decreased as press intensity increased or when factors counteracting regime shifts weakened. These multiple lines of evidence suggest that conceptualizing regime shifts as an interactive function of the intensity and duration of driver changes will increase understanding of the varying effects of driver presses, pulses, and cycles on ecosystem dynamics.

show abstract

Section: Duration Effects In Generalsupporting

confidence: 76%

The interactive effects of press/pulse intensity and duration on regime shifts at multiple scales

Ratajczak

D’Odorico

Collins

et al. 2017

Ecological Monographs

View full text Add to dashboard Cite

show abstract

“…), or the timescale over which reversibility occurs (Augustine et al. ). Understanding how disturbance properties relate to threshold dynamics is key to managers’ ability to prevent or reverse undesirable transitions, or to precipitate transitions to desirable states.…”

Section: Introductionmentioning

confidence: 99%

Thresholds are in the eye of the beholder: plants and wildlife respond differently to short‐term cattle corrals

Veblen

Porensky

2019

Ecological Applications

View full text Add to dashboard Cite

Citation: Veblen, K. E., and L. M. Porensky. 2019. Thresholds are in the eye of the beholder: plants and wildlife respond differently to short-term cattle corrals. Ecological Applications 29(8):Abstract. Rangelands are governed by threshold dynamics, and factors such as drought, wildfire, and herbivory can drive change across thresholds and between ecological states. Most work on this topic has focused on shifts in a single response variable, vegetation, and little research has considered how to reconcile responses of more than one variable to determine whether a system has undergone a genuine state change. In sub-Saharan Africa, mobile overnight livestock corrals (bomas) can be used by managers to precipitate ecological transitions from areas dominated by bare ground to productive ecosystem hotspots (glades) that are attractive to wild herbivores. We asked how long bomas must be occupied by cattle before undergoing a state change, considering both plant and animal response variables, to glade ecosystem hotspots. We tested five durations of boma occupation: 0, 4, 7, 14, and 28 days. Each treatment was replicated five times, and we assessed vegetation as well as herbivore dung (as a proxy of use) at multiple time points over 3 yr following boma abandonment. Vegetation in 7-, 14-, and 28-d boma duration treatments appeared to undergo a complete transition to glade-like plant communities, whereas the shortest 4-d treatment had not converted to a glade plant community by year 3. Wildlife responses appeared to lag behind vegetation responses, with transitions to glade-like herbivore use occurring only in the longest duration (14-and 28d) treatments. Our results show that different response variables, when considered individually, may provide incomplete or misleading information about state changes. Although shorteroccupied bomas might be effective for reducing bare ground, they may not attract enough wild herbivores to constitute crossing into an alternative state. Understanding threshold dynamics associated not only with vegetation responses but with a broader suite of response variables is challenging, but will provide a more complete representation of ecosystem function and greater opportunity for more successful ecosystem management.

show abstract

“…The seed source driving this recovery can come from either the on-site seed bank or dispersed from adjacent, uncolonized areas. Historically, as well as in previously conducted studies (Osborn and Allan 1949, Hartley et al 2009, Augustine et al 2014, prairie dog colonies were in a landscape matrix that was dominated by native vegetation, ungrazed by prairie dog. In these less anthropogenically influenced landscapes, prairie dog removal due to management intervention or plague epizootics successfully restored plaguepresent colony plant communities to compositions equivalent to unoccupied areas (Osborn and Allan 1949, Hartley et al 2009, Augustine et al 2014.…”

Section: Discussionmentioning

confidence: 95%

“…Classical restoration from prairie dog grazing demands the recovery of native grasses and the demise of non-native plant species that typically benefit or are relatively unharmed by the presence of prairie dogs (Osborn and Allan 1949, Hartley et al 2009, Augustine et al 2014. The seed source driving this recovery can come from either the on-site seed bank or dispersed from adjacent, uncolonized areas.…”

Section: Discussionmentioning

confidence: 99%

“…When plague enters a prairie dog colony, it results in mortality rates greater than 95% (Cully and Williams 2001). Studies on plant community changes resulting from prairie dog removal in natural areas either via plague (Hartley et al 2009, Augustine et al 2014 or eradication (Osborn and Allan 1949) suggest that most plant characteristics on plague extirpated colonies were no different from adjacent off colony areas (Hartley et al 2009), and community recovery can occur less than five years after removal (Augustine et al 2014). However, previous colony restoration studies (Osborn and Allan 1949, Hartley et al 2009, Augustine et al 2014 were conducted in less anthropogenically influenced landscapes with a matrix dominated by large areas of native plant communities.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Resilience of a novel ecosystem after the loss of a keystone species: plague epizootics and urban prairie dog management

et al. 2015

View full text Add to dashboard Cite

Abstract. In a complex urban-impacted landscape, native black-tailed prairie dogs (Cynomys ludovicianus) amplify the trajectory at which grassland plant communities deviate from historical configurations. Prairie dog removal has been proposed as an intervention method based upon the premise that removing a major directional driver of change will initiate the recovery of historically common plant communities. However, in a heavily anthropogenically influenced landscape with a matrix containing only small fragmented areas of native vegetation, the recolonization speed and success of native plant species may not match those observed in less anthropogenically influenced landscapes. This study examined the effect of urban prairie dog removal by using remote sensing to observe the response of plant communities near Boulder, Colorado, USA to plague epizootics. We used Mann-Whitney U tests to compare the soil adjusted vegetation index (SAVI) values from colonies recently extirpated by plague to both areas unoccupied by prairie dogs and to plague-absent colonies. Analysis of 67 Landsat images in three growing season subsets suggested that prairie dog removal alone does not return colony plant communities to compositions representative of grassland areas unoccupied by prairie dogs. The absence of SAVI value changes in the mid-and lategrowing seasons suggested that novel vegetation communities on urban prairie dog colonies were highly resilient systems, and prairie dog removal alone was insufficient for restoration. Furthermore, increased early season SAVI values on extirpated colonies could indicate a proliferation of introduced winter active species and exotic forbs, not the desired reemergence of native species, but rather species expected given current climatic changes. Intensive management efforts appear necessary for overcoming the thresholds required to restore urban prairie dog colonies to their historical compositions, an effort made increasingly more difficult with the ongoing effects of other global change drivers.

show abstract

Testing for Thresholds in a Semiarid Grassland: The Influence of Prairie Dogs and Plague

Cited by 19 publications

References 38 publications

The interactive effects of press/pulse intensity and duration on regime shifts at multiple scales

The interactive effects of press/pulse intensity and duration on regime shifts at multiple scales

Thresholds are in the eye of the beholder: plants and wildlife respond differently to short‐term cattle corrals

Resilience of a novel ecosystem after the loss of a keystone species: plague epizootics and urban prairie dog management

Contact Info

Product

Resources

About