Transient population dynamics impede restoration and may promote ecosystem transformation after disturbance

Abstract

The apparent failure of ecosystems to recover from increasingly widespread disturbance is a global concern. Despite growing focus on factors inhibiting resilience and restoration, we still know very little about how demographic and population processes influence recovery. Using inverse and forward demographic modelling of 531 post‐fire sagebrush populations across the western US, we show that demographic processes during recovery from seeds do not initially lead to population growth but rather to years of population decline, low density, and risk of extirpation after disturbance and restoration, even at sites with potential to support long‐term, stable populations. Changes in population structure, and resulting transient population dynamics, lead to a > 50% decline in population growth rate after disturbance and significant reductions in population density. Our results indicate that demographic processes influence the recovery of ecosystems from disturbance and that demographic analyses can be used by resource managers to anticipate ecological transformation risk.

Intraspecific variation in surface water uptake in a perennial desert shrub

“…Big sagebrush is a long‐lived perennial that requires extensive monitoring to understand its demographic variation (Germino, Moser, et al, ; Shriver et al, ). The acquisition of soil resources (e.g.…”

Fire and development influences on sagebrush community plant groups across a climate gradient in northern Nevada

“…, Mahood and Balch , Shriver et al. ). Shrub response to fire is also influenced by community type and topography (Mata‐González et al.…”

“…), and demographic effects (Shriver et al. ). Additional fires further decrease cover and moreover can lead to simplification of communities (Mahood and Balch ).…”

“…A single fire could result in significant community shifts and slow recovery, especially at warmer, drier, and lower elevation sites (Baker 2006, Knutson et al 2014, Mahood and Balch 2019, Shriver et al 2019. Shrub response to fire is also influenced by community type and topography (Mata-Gonz alez et al 2018), post-fire soil moisture (Shriver et al 2018), and demographic effects (Shriver et al 2019). Additional fires further decrease cover and moreover can lead to simplification of communities (Mahood and Balch 2019).…”

Integrating Ecosystem Resilience and Resistance Into Decision Support Tools for Multi-Scale Population Management of a Sagebrush Indicator Species

“…Despite prolific seed production, other functional traits of sagebrush species dominating the Great Basin (e.g., mountain big, Wyoming big, black, and low) such as fire-induced mortality, slow-growth rates, lack of biotic and abiotic dispersal mechanisms, and high seed and seedling mortality (Pyke, 2011;Knutson et al, 2014;Schlaepfer et al, 2014;Shriver et al, 2019) hinder multiple types of resilience in the face of altered or novel disturbances, which includes the grass-fire cycle. Ecological and spatial resilience has been stressed by an increase in fire size, recurrence rates, and rotation intervals over at least the past 30 years (Brooks et al, 2015), which collectively provide more sustained energy to push heterogenous sagebrush communities into homogeneous cheatgrass-dominated states across large extents, particularly those with soil climates associated with low R&R that dominate (i.e., comprise over 50%) the Great Basin (Maestas et al, 2016).…”