Multiple mechanisms of early plant community assembly with stochasticity driving the process

Abstract

Abstract. Initial plant establishment is one of the most critical phases in ecosystem development, where an early suite of physical (environmental filtering), biological (seed limitation, species interactions) and stochastic factors may affect successional trajectories and rates. While functional traits are commonly used to study processes that influence plant community assembly in late successional communities, few studies have applied them to primary succession. The objective here was to determine the importance of these factors in shaping early plant community assembly on a glacial outwash plain, Skeiðararsandur, in SE Iceland using a trait based approach. We used data on vascular plant assemblages at two different spatial scales (community and neighborhood) sampled in 2005 and 2012, and compiled a dataset on seven functional traits linked to species dispersal abilities, establishment, and persistence for all species within these assemblages. Trait-based null model analyses were used to determine the processes that influenced plant community assembly from the regional species pool into local communities, and to determine if the importance of these processes in community assembly was dependent on local environment or changed with time. On the community scale, for most traits, random processes dominated the assembly from the regional species pool. However, in some communities, there was evidence of non-random assembly in relation to traits linked to species dispersal abilities, persistence, and establishment. On the neighborhood scale, assembly was mostly random. The relative importance of different processes varied spatially and temporally and the variation was linked to local soil conditions. While stochasticity dominated assembly patterns of our early successional communities, there was evidence of both seed limitation and environmental filtering. Our results indicated that as soil conditions improved, environmental constraints on assembly became weaker and the assembly became more dependent on species availability.

Effects of cover soil stockpiling on plant community development following reclamation of oil sands sites in Alberta

“…Very limited positive and negative co‐occurrence patterns in our study indicate largely random plant community assembly with reclaimed ecosystems being unstructured—24 years after reclamation. A similar plant community assembly pattern was also reported on open‐cast lignite mine restoration in northeastern Germany (Zaplata et al ; Ulrich et al ), on a glacier outwash plain sites restoration in Iceland (Marteinsdóttir et al ), and oil sand reclamation sites in Alberta (Dhar et al , ). Based on the studies by Dhar et al (, ) plant community assembly in oil sands reclamation sites showed a random pattern of community assembly when peat–mineral mix was used as a cover soil.…”

Understorey succession after burial by tephra from Mount St. Helens

“…Our data support a more dynamic understanding of secondary succession, where both resilience models and alternative steady‐state models can be true in the same vegetation zone. As such, our data contribute to a growing body of literature supporting a more dynamic understanding of the complexities of succession generally (Christensen, ; Marteinsdóttir et al, ; Meiners, Cadotte, Fridley, Pickett, & Walker, ), and secondary succession more specifically (Donato, Campbell, & Franklin, ; Måren et al, ).…”

“…Historically, major ideas about ecosystem succession have moved from simple models where ecosystems progress towards a stable climax dependent on climate (Clements, 1916), towards a more complex understanding of vegetation change and multiple successional trajectories dependent on abiotic factors, the nature of disturbance, species dispersal patterns, priority and legacy effects, available resources, and plant growth habit and vegetative traits (Buma et al, 2017;Christensen, 2014;Fukami, 2015;Måren, Kapfer, Aarrestad, Grytnes, & Vandvik, 2018;Marteinsdóttir, Svavarsdóttir, & Thórhallsdóttir, 2018;Swanson & Major, 2005;Tilman, 1985). When considering secondary succession, the concept of ecosystem resilience suggests that systems will return to an original state following a disturbance.…”

Forest community assembly is driven by different strata‐dependent mechanisms along an elevational gradient

“…dispersal limitation), which in turn could limit dispersal (Murphy, Salpeter, & Comita, ). For example, it was demonstrated that stochasticity drives early plant community assembly due to seed limitation (Marteinsdottir, Svavarsdottir, & Thorhallsdottir, ). Aside from random patterns, the differences in phylogenetic and functional structure might also be attributed to random species colonization and extinction (Liu, Chen, & Yang, ), although these processes remain to be tested at our study site.…”