Creosote growth rate and reproduction increase in postfire environments

Abstract

Human activities are changing patterns of ecological disturbance globally. In North American deserts, wildfire is increasing in size and frequency due to fuel characteristics of invasive annual grasses. Fire reduces the abundance and cover of native vegetation in desert ecosystems. In this study, we sought to characterize stem growth and reproductive output of a dominant native shrub in the Mojave Desert, creosote bush (Larrea tridentata (DC.) Coville) following wildfires that occurred in 2005. We sampled 55 shrubs along burned and unburned transects 12 years after the fires (2017) and quantified age, stem diameter, stem number, radial and vertical growth rates, and fruit production for each shrub. The shrubs on the burn transects were most likely postfire resprouts based on stem age while stems from unburn transects dated from before the fire. Stem and vertical growth rates for shrubs on burned transects were 2.6 and 1.7 times higher than that observed for shrubs on unburned transects. Fruit production of shrubs along burned transects was 4.7‐fold more than shrubs along paired unburned transects. Growth rates and fruit production of shrubs in burned areas did not differ with increasing distance from the burn perimeter. Positive growth and reproduction responses of creosote following wildfires could be critical for soil stabilization and re‐establishment of native plant communities in this desert system. Additional research is needed to assess if repeat fires that are characteristic of invasive grass‐fire cycles may limit these benefits.

Resilience and alternative stable states after desert wildfires

“…However, L . tridentata 's ability to at least occasionally resprout and grow comparatively fast (Molinari et al 2019) could account for more resilience in the Larrea than in the Coleogyne community. Coleogyne ramosissima lacks resprouting capability, forms minimal persistent soil seed banks, is a temporally irregular mast‐seeder dependent on abundant seed‐producing adults, exhibits minimal seed dispersal, grows slowly (often only 0.5–1 cm in height/yr), and may rely on a “seedling bank” readily destroyed by fire (Pendleton et al 2015).…”

Wildfire Risk and Hazardous Fuel Reduction Treatments Along the US-Mexico Border: A Review of the Science (1986-2019)

“…These studies found reduced woody plant abundance following prescribed burns in most cases, 55,[58][59][60] but woody regeneration and interactions with grass species were variable depending on the fire season, fire return interval, and the degree of livestock grazing. 21,34,[61][62][63] Fire rather than livestock grazing may have a larger role in maintaining grass dominance in the border region, although the mechanisms behind the balance of woody plants and grasses remain controversial. 56 Reductions in woody plant cover had a positive effect on wildlife species requiring more open and grass-dominated habitat, but negative effects on wildlife species requiring a higher density of woody vegetation.…”

Wildfire and cattle legacies on gradients of soil nitrogen underlie patterns of annual brome invasion

“…4). This may be partially due to N inputs from the re itself or competition release of soil resources related to re-related losses of native shrubs or a combination of the two (Horn et al, 2015, Molinari et al, 2019. These results suggest that red brome is perpetuated through post-re enrichment of inorganic N, which may have important implications for increasing ne fuel continuity that drives invasive grass re cycles in desert ecosystems.…”