Early life‐history stages drive community reassembly in Australian old‐fields

Abstract

Questions Do native annual forb seedling communities reassemble after agricultural abandonment to an undisturbed condition? Do environmental changes associated with cultivation affect seedling establishment? Is post‐abandonment recovery of seedling and vegetation communities more limited by seed availability, seedling establishment or seedling survival? Location Northern Victoria, Australia. Methods Seedling density, species richness and composition were sampled across a 100‐yr chronosequence. Standing vegetation, cover of the biological soil crust and soil properties were sampled from the same plots, and the seed bank was sampled from the same sites. Patterns were compared among the seedlings, seed bank and vegetation. Results Native seedling density and species richness did not increase with time‐since‐abandonment, despite some recovery in species composition. Native density and richness were negatively associated with soil fertility and bare ground and positively associated with biological soil crust cover; exotics showed the opposite pattern. Species composition showed little association with soil resources. Percentage field emergence from the seed bank was unaffected by time‐since‐abandonment. Compositional similarity between the seedlings and vegetation was higher (81%) than that between the seedlings and seed bank (61%); neither was affected by time‐since‐abandonment. Conclusions While environmental conditions partially determined patterns of seedling recruitment, seed availability was the main driver of seedling density and composition with time‐since‐abandonment. Post‐establishment mortality was apparently not a major determinant of species composition of the standing vegetation. Thus, seed and microsite limitation interacted to drive community reassembly, but seed availability was relatively more important.

Growth responses of five desert plants as influenced by biological soil crusts from a temperate desert, China

“…Studies show biocrusts can have a positive influence on the colonization of vascular plants in the field in many settings, including polar (Anderson and Bliss 1998;Bliss and Gold 1999;Cooper et al 2004;Breen and Levesque 2006), cool (Harper and Belnap 2001), and hot arid areas (DeFalco et al 2001;Scott and Morgan 2012).…”

“…Biocrusts can affect germination and establishment of vascular plants, although their influence can be positive, negative, or neutral, depending on the species of plant and the external morphology and composition of the biocrust community (Zaady et al 1997;Prasse and Bornkamm 2000;Gutterman 2003;Hawkes 2004;L i et al 2005;Serpe et al 2006;Deines et al 2007;Escudero et al 2007). Studies show biocrusts can have a positive influence on the colonization of vascular plants in the field in many settings, including polar (Anderson and Bliss 1998;Bliss and Gold 1999;Cooper et al 2004;Breen and Levesque 2006), cool (Harper and Belnap 2001), and hot arid areas (DeFalco et al 2001;Scott and Morgan 2012).…”

Multiple assessments of succession rates on Mount St. Helens

“…Time to a benchmark is useful in broad geographic comparisons (Cutler 2010, Wright andFridley 2010), chronosequence studies (Lindig-Cisneros et al 2006) or for comparisons in short-term experiments (Scott andMorgan 2012, Munson andLaurenroth 2012), while species turnover can be applied at any stage of development and offers ways to test the effects of regulating factors (del Moral and Magnússon 2014).…”

Biocrusts and their disturbance mediate the recruitment of native and exotic grasses from a hot desert ecosystem

“…, Godínez‐Alvarez et al. , Scott and Morgan ). In contrast, past studies have also demonstrated the capacity of exotic plant species growth to benefit from soil resource availability provided by biocrusts.…”

“…Following emergence, biocrusts may offer favorable soil conditions for seedling establishment and growth (Zhang et al 2016) by increasing the availability of soil water and nutrients including greater soil organic matter and inorganic N (DeFalco et al 2001, Pendleton et al 2003. Benefits of biocrusts to native plant growth have been shown in a variety of ecosystems including cold (Bliss and Gold 1999, Elmarsdottir et al 2003, Breen and Levesque 2006, cool (Lesica and Shelly 1992, Harper and Belnap 2001, Zhang and Nie 2011, and hot desert ecosystems (DeFalco et al 2001, God ınez-Alvarez et al 2012, Scott and Morgan 2012. In contrast, past studies have also demonstrated the capacity of exotic plant species growth to benefit from soil resource availability provided by biocrusts.…”