Fire induced reproductive mechanisms of a Symphoricarpos (Caprifoliaceae) shrub after dormant season burning

Abstract

BackgroundSymphoricarpos, a genus of the Caprifoliaceae family, consists of about 15 species of clonal deciduous shrubs in North America and 1 species endemic to China. In North American tallgrass prairie, Symphoricarpos orbiculatus (buckbrush) is the dominant shrub often forming large colonies via sexual and asexual reproductive mechanisms. Symphoricarpos shrubs, in particular S. orbiculatus, use a unique sexual reproductive mechanism known as layering where vertical stems droop and the tips root upon contact with the soil. Because of conflicting societal values of S. orbiculatus for conservation and agriculture and the current attempt to restore historical fire regimes, there is a need for basic research on the biological response of S. orbiculatus to anthropogenic burning regimes.ResultsFrom 2007 through 2013 we applied prescribed fires in the late dormant season on grazed pastures in the Grand River Grasslands of Iowa. From 2011 to 2013, we measured how S. orbiculatus basal resprouting and layering stems were affected by patchy fires on grazed pastures, complete pasture fires on grazed pastures or fire exclusion without grazing for more than three years. We measured ramet height, ramet canopy diameter, stems per ramet, ramets per 100 m2, and probability of new layering stems 120 days after fire. Height in burned plots was lower than unburned plots but S. orbiculatus reached ~ 84% of pre-burn height 120 days after fire. Stems per ramet were 2x greater in the most recently burned plots due to basal re-sprouting. Canopy diameter and density of ramets was not affected by time since fire, but burned pastures had marginally lower densities than plots excluded from fire (P = 0.07). Fire triggered new layering stems and no new layering stems were found in plots excluded from fire.ConclusionsThe mechanisms of both basal sprouting and aerial layering after fire suggest S. orbiculatus is tolerant to dormant season fires. Furthermore, dormant season fires, regardless if they were patchy fires or complete pasture fires, did not result in mortality of S. orbiculatus. Dormant season fires can reduce S. orbiculatus structural dominance and maintain lower ramet densities but also trigger basal resprouting and layering.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-014-0080-4) contains supplementary material, which is available to authorized users.

Shrubland resilience varies across soil types: implications for operationalizing resilience in ecological restoration

“…Resprouting is a common life history strategy in highly disturbed ecosystems such as grasslands that experience frequent fi res (Bond and Midgley 2003 ). Resprouting provides a mechanism for woody-plant tolerance to low-intensity fi res, especially during the dormant season when woody plants are not actively photosynthesizing (Scasta et al 2014 ). Woody plants are able to withstand low-intensity fi res through nonstructural carbohydrate storage in stems, roots, and lignotubers, as well as belowground meristematic tissues insulated from high temperatures by the soil (Clarke et al 2010(Clarke et al , 2013.…”

Restoring the fire–grazing interaction promotes tree–grass coexistence by controlling woody encroachment

“…In addition, they can physiologically adapt after fire and herbivory by overcompensating (i.e., growing larger than before) and adopting a pole-like growth form to maximize height Keeley 2005, Ramula et al 2019). Some woody species also bypass the fire-trap by reproducing vegetatively (Ratajczak et al 2011, Scasta et al 2014.…”

Fire Severity and Regeneration Strategy Influence Shrub Patch Size and Structure Following Disturbance

“…Sprouting appears to be an effective regeneration strategy that yields high variability in post-fire shrub structure. Obligate resprouting species can regenerate from rhizomes or from the root crown, and some species are capable of regenerating from both root crowns and rhizomes [7,8], and even of spreading asexually through adventitious rooting of aerial stems [54]. Adventitious rooting produces new sites at which post-fire sprouting could occur, and although this phenomenon was not directly observed in this study, it could have effects on shrub patch structure [54].…”

“…Obligate resprouting species can regenerate from rhizomes or from the root crown, and some species are capable of regenerating from both root crowns and rhizomes [7,8], and even of spreading asexually through adventitious rooting of aerial stems [54]. Adventitious rooting produces new sites at which post-fire sprouting could occur, and although this phenomenon was not directly observed in this study, it could have effects on shrub patch structure [54]. When regeneration strategy is evaluated across fire severities (Figure 4), obligate resprouters are proportionally much more common following lower fire severity, probably because unburned and low-severity burned areas are characterized by intact overstory canopy, and low-severity fire does not totally kill the root and stump rhizomes of sprouting species.…”