Evaluating the effect of rainfall variability on vegetation establishment in a semidesert grassland

Fehmi, Jeffrey S.; Niu, Guo Yue; Scott, Russell L.; Mathias, Andrea

doi:10.1007/s10661-013-3384-z

Cited by 20 publications

(9 citation statements)

References 52 publications

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“…Exotic species invasions, overgrazing, mining, agriculture, and other factors have extensively degraded dryland ecosystems throughout the world (e.g., Knapp 1996, Jones and Schmitz 2009, Merritt and Dixon 2011. Recent decades have ushered in major efforts to reverse this degradation, but these efforts have proven highly prone to failure (Wilson et al 2004, MacDougall et al 2008, Rinella et al 2012, Fehmi et al 2014). Of the three major plant groups comprising dryland plant communities (grasses, forbs, shrubs), restoration of shrubs has proven most failure prone.…”

Section: Introductionmentioning

confidence: 99%

High precipitation and seeded species competition reduce seeded shrub establishment during dryland restoration

Rinella

Hammond

Bryant

et al. 2015

Ecological Applications

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Drylands comprise 40% of Earth's land mass and are critical to food security, carbon sequestration, and threatened and endangered wildlife. Exotic weed invasions, overgrazing, energy extraction, and other factors have degraded many drylands, and this has placed an increased emphasis on dryland restoration. The increased restoration focus has generated a wealth of experience, innovations and empirical data, yet the goal of restoring diverse, native, dryland plant assemblages composed of grasses, forbs, and shrubs has generally proven beyond reach. Of particular concern are shrubs, which often fail to establish or establish at trivially low densities. We used data from two Great Plains, USA coal mines to explore factors regulating shrub establishment. Our predictor data related to weather and restoration (e.g., seed rates, rock cover) variables, and our response data described shrub abundances on fields of the mines. We found that seeded non-shrubs, especially grasses, formed an important competitive barrier to shrub establishment: With every one standard deviation increase in non-shrub seed rate, the probability shrubs were present decreased ~0.1 and shrub cover decreased ~35%. Since new fields were seeded almost every year for > 20 years, the data also provided a unique opportunity to explore effects of stochastic drivers (i.e., precipitation, year effects). With every one standard deviation increase in precipitation the first growing season following seeding, the probability shrubs were present decreased ~0.07 and shrub cover decreased ~47%. High precipitation appeared to harm shrubs by increasing grass growth/competition. Also, weak evidence suggested shrub establishment was better in rockier fields where grass abundance/competition was lower. Multiple lines of evidence suggest reducing grass seed rates below levels typically used in Great Plains restoration would benefit shrubs without substantially impacting grass stand development over the long term. We used Bayesian statistics to estimate effects of seed rates and other restoration predictors probabilistically to allow knowledge of the predictors' effects to be refined through time in an adaptive management framework. We believe this framework could improve restoration planning in a variety of systems where restoration outcomes remain highly uncertain and ongoing restoration efforts are continually providing new data of value for reducing the uncertainty.

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Section: Introductionmentioning

confidence: 99%

High precipitation and seeded species competition reduce seeded shrub establishment during dryland restoration

Rinella

Hammond

Bryant

et al. 2015

Ecological Applications

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“…Sowing a mixture of T and UT seeds with different environmental cues is practical, cost‐effective and a means of capitalizing on inherently variable precipitation regimes (Ogle & Reynolds ; Fehmi et al . ). Treated seeds will respond quickly, whereas UT seeds can remain dormant for lengthy periods depending on species, wet/dry cycling, temperature regime and age (Baskin & Baskin ).…”

Section: Discussionmentioning

confidence: 97%

“…Exclusively sowing T seeds is not without risk, especially when germination is triggered but not followed by subsequent precipitation, as seedling mortality in arid environments is generally greatest during the first dry period following emergence (Lloret et al 1999). Sowing a mixture of T and UT seeds with different environmental cues is practical, cost-effective and a means of capitalizing on inherently variable precipitation regimes (Ogle & Reynolds 2004;Fehmi et al 2014). Treated seeds will respond quickly, whereas UT seeds can remain dormant for lengthy periods depending on species, wet/dry cycling, temperature regime and age (Baskin & Baskin 1998).…”

Section: Discussionmentioning

confidence: 99%

Seed dormancy, soil type and protective shelters influence seedling emergence at Shark Bay, Western Australia: Insight into global dryland revegetation

Mayence¹,

Carrick

Beem³

et al. 2017

Eco Management Restoration

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Summary Seedling emergence is a major constraint on dryland revegetation success. In this study, we investigated seedling emergence of six framework shrub species as influenced by seed treatment, soil type and protective shelters using a large field trial in arid Western Australia. We observed the main effects of seed treatment and soil type to account for the majority of the variation in emergence. For species that exhibit pronounced dormancy, we found emergence of dormancy‐alleviated or treated (T) seed to be significantly greater than dormant or untreated (UT) seed, with responses varying across species (e.g. 41 times greater for Acacia ligulata Benth., and 10 times greater for Stylobasium spathulatum Desf.). For shallowly or nondormant species like Senna glutinosa (DC) Randall, UT seed emergence was slightly greater than for T seed. Compared to subsoil, topsoil was more receptive to infiltration (3.44 vs. 0.38 mm/min), and less prone to compaction (1.24 vs. 1.67 g/cm3) and crusting (0.6 vs. 1.3 kg/cm2); however, subsoil had greater moisture retention. Shelters failed to benefit soil moisture retention in either soil type, but enhanced emergence for most species. This study provides insight into how various cost‐effective treatments can be utilized to manipulate seed dormancy to optimize seedling emergence, the intrinsic value of topsoil as a superior growth medium and the benefit of novel, low‐cost shelters for enhancing seedling emergence. In arid environments, sowing T seed in combination with UT seed increases the likelihood of capitalizing on inherently variable precipitation events.

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“…If increasing grass cover is an important component of regional management goals, then herbivory impacts and population dynamics of native lagomorphs need to be considered by land managers when attempting shrubland‐to‐grassland restoration projects. The low recruitment from seeds observed in this experiment is a common challenge to restoration in the region, as recruitment relies on both the amount and distribution of rainfall, which can be highly variable from year to year (Fehmi, Niu, Scott, & Mathias, ). The compounding effects of high herbivory pressure and low recruitment due to the variability of rainfall may substantially limit and prolong the recovery of grasses following livestock removal, which can already take decades (Valone et al, ).…”

Section: Discussionmentioning

confidence: 99%

Native lagomorphs suppress grass establishment in a shrub‐encroached, semiarid grassland

Abercrombie

Koprowski

Nichols

et al. 2018

Ecology and Evolution

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Shrub encroachment into arid grasslands has been associated with reduced grass abundance, increased soil erosion, and local declines in biodiversity. Livestock overgrazing and the associated reduction of fine fuels has been a primary driver of shrub encroachment in the southwestern United States, but shrublands continue to persist despite livestock removal and grassland restoration efforts. We hypothesized that an herbivory feedback from native mammals may contribute to continued suppression of grasses after the removal of livestock. Our herbivore exclusion experiment in southeastern Arizona included five treatment levels and allowed access to native mammals based on their relative body size, separating the effects of rodents, lagomorphs, and mule deer. We included two control treatments and replicated each treatment 10 times (n = 50). We introduced uniform divisions of lawn sod (Cynodon dactylon) into each exclosure for 24‐hr periods prior to (n = 2) and following (n = 2) the monsoon rains and used motion‐activated cameras to document herbivore visitations. In the pre‐monsoon trials, treatments that allowed lagomorph access had less sod biomass relative to other treatments (p < 0.001), averaging 44% (SD 36%) and 29% (SD 45%) remaining biomass after the 24‐hr trial periods. Following the onset of monsoons, differences in remaining biomass among treatments disappeared. Desert cottontails (Sylvilagus audubonii) were detected more frequently than any of the other 11 herbivore species present at the site, accounting for 83% of detections during the pre‐monsoon trials. Significantly more (p < 0.001) desert cottontails were detected during the pre‐monsoon trials (2,077) compared to the post‐monsoon trials (174), which coincided with biomass removal from lagomorph accessible treatments. We conclude that desert cottontails are significant consumers of herbaceous vegetation in shrub‐encroached arid grasslands and they, along with other native herbivores, may act as a biotic feedback contributing to the competitive advantage and persistence of shrubs.

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Evaluating the effect of rainfall variability on vegetation establishment in a semidesert grassland

Cited by 20 publications

References 52 publications

High precipitation and seeded species competition reduce seeded shrub establishment during dryland restoration

High precipitation and seeded species competition reduce seeded shrub establishment during dryland restoration

Seed dormancy, soil type and protective shelters influence seedling emergence at Shark Bay, Western Australia: Insight into global dryland revegetation

Native lagomorphs suppress grass establishment in a shrub‐encroached, semiarid grassland

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