Post‐fire succession of seeding treatments in relation to reference communities in the Great Basin

Abstract

Questions Post‐fire seeding has been widely implemented in the semiarid Great Basin because natural vegetation recovery may be compromised. Non‐native species are often seeded to rapidly establish perennial cover and compete with invasive annuals. We asked whether seeding treatments with different amounts of native and non‐native species followed different successional trajectories and whether they became more similar to reference communities over time. We considered restoration implications of seed mix choices and reference community options involving: (a) local unburned vegetation; and (b) reference states mapped by the USDA Natural Resources Conservation Service (NRCS) based on soil–vegetation associations. Location Tintic Valley, UT, USA. Methods Four post‐fire seeding treatments differing by seed mix were installed alongside an unseeded control (USC) at two sites. Two seed mixes were comprised of native species and two were predominantly non‐native. Vegetation was monitored 1–3 and 16–18 years after fire and seeding. Reference communities were characterized and compared using hierarchical clustering. Non‐metric multidimensional scaling and permutation tests were used to determine successional trajectories of post‐fire treatments in relation to reference communities. Results Local unburned reference communities had fewer herbaceous perennials and higher woody cover than NRCS reference communities, suggesting departure from conditions expected under minimal post‐settlement disturbance. USCs became more similar to reference communities over time, though less so at a site with abundant invasive annuals. Trajectories of seeded treatments were driven by seed mix species, with native‐only mixes approaching reference communities more closely than mixes with non‐natives. Conclusions Gradual recovery of reference community composition is possible without seeding but the degree and rate of recovery can vary by site. Seeding can accelerate perennial vegetation recovery but may result in alternative successional trajectories, especially if non‐native species are seeded. Carefully selected reference communities can serve as guides for formulating seed mixes when restoration of natural vegetation is desired.

Not all seed transfer zones are created equal: using fire history to identify seed needs in the Cold Deserts of the western United States

“…With climate change and other anthropogenic disturbances, even fire‐adapted ecosystems may require active restoration to return to desirable states (Fulé 2008). For many plant communities, the question is not whether they will burn, but when (Pitman et al 2007; Liu & Wimberly 2016), and what type of management may be needed to maintain desired successional trajectories (Ott et al 2022). Sagebrush steppe shrubland, the predominant vegetation type in the western U.S.…”

“…Nevertheless, short‐term targets for soil stabilization and annual grass suppression have met with mixed success (Knutson et al 2014), and attempts at establishing diverse native plant communities that support wildlife populations of conservation concern have generally been unsuccessful (Arkle et al 2014). In addition to the challenges of restoring heavily invaded arid sites, these outcomes are influenced by the prominent use of non‐native Eurasian bunchgrasses, which establish well and can outcompete annual grasses (Ott et al 2019), but interfere with native species recovery (Nafus et al 2015; Williams et al 2017; Ott et al 2022). However, even when native species are used, which is occurring with increasing frequency (Pilliod et al 2017 b ), native seed sources may fail to establish and thrive due in part to a mismatch between the source environment, where the population has been subject to natural selection, and the environment at the restoration site (McKay et al 2005).…”

Not all seed transfer zones are created equal: Using fire history to identify seed needs in the Cold Deserts of the Western US

“…With climate change and other anthropogenic disturbances, even fire-adapted ecosystems may require active restoration to return to desirable states (Fulé 2008). For many plant communities, the question is not whether they will burn, but when (Pitman et al 2007; Liu & Wimberly 2016), and what type of management may be needed to maintain desired successional trajectories (Ott et al 2022). Sagebrush steppe shrubland, the predominant vegetation type in the western United States Cold Deserts, is made up of plant communities that are vulnerable and maladapted to increased wildfire (Winward 1985).…”

“…Nevertheless, short-term targets for soil stabilization and annual grass suppression have met with mixed success (Knutson et al 2014), and attempts at establishing diverse plant communities that support wildlife populations of conservation concern have generally been unsuccessful (Arkle et al 2014). In addition to the challenges of restoring heavily invaded arid sites, these outcomes are likely due to the prominent use of non-native Eurasian bunchgrasses, which establish well and can outcompete annual grasses (Ott et al 2019), but interfere with native species recovery (Nafus et al 2015; Williams et al 2017; Ott et al 2022).…”