Resource availability mediates the importance of priority effects in plant community assembly and ecosystem function

Abstract

Assembly history, including the order in which species arrive into a community, can influence long‐term community structure; however we know less about how timing of species arrival may alter assembly especially under varying resource conditions. To explore how the timing of species arrival interacts with resource availability to alter community assembly, we constructed experimental plant communities and manipulated the interval between plantings of groups of seedlings (0, 5, 10, 15 or 20 days) at low and high levels of soil nutrient supply. To see if community changes influenced ecosystem‐scale processes, we measured parameters across the plant–soil continuum (e.g. plant biomass and net ecosystem carbon dioxide exchange). We found that the timing of species arrival had a large impact on community assembly, but the size of the effect depended on soil fertility. As planting interval increased, plant communities diverged further from the control, but the divergence was stronger at high than at low nutrient supply. Our data suggest that at high nutrient supply, early‐planted species preempted light resources more quickly, thus preventing the successful establishment of later arriving species even at short planting intervals. Finally, we found that assembly related divergence in plant communities scaled to impact ecosystem‐level characteristics such as green leaf chemistry, but had little effect on total community biomass and net ecosystem exchange of CO2 and water vapor. Our data indicate that the effect of a stochastic factor, here the timing of species arrival on community composition, depends on the resource level under which the community assembles.

Stochasticity, succession, and environmental perturbations in a fluidic ecosystem

“…In addition, nutrient addition could strengthen priority effects (13). Enhanced growth of early-arriving species could result in the exclusion or facilitation of later arriving species (17). All of the above could lead to unpredictable site-tosite variation in species compositions (i.e., compositional stochasticity) under similar environmental conditions.…”

“…It is also known that several factors such as habitat connectivity and size (4), productivity (15), disturbance (13), predation (10), and resource availability (17) influence the relative importance of stochastic vs. deterministic processes in the assembly of local communities. However, it is not clear whether and how their relative importance varies with time.…”

Priority effects are affected by precipitation variability and are stronger in exotic than native grassland species

“…This priority effect was stronger in high than low resource environments. Similarly, nutrient additions can increase the strength of priority effects, allowing early arriving species to gain higher levels of resources compared to a less enriched environment (Jarchow and Liebman 2012;Kardol et al 2013). When nutrients are abundant, even slight differences between early community compositions can lead to distinct community formations (Houseman et al 2008).…”

“…Priority effects can vary in strength not just in response to phenological traits, but also to abiotic conditions (Jarchow and Liebman 2012;Kardol et al 2013;Tucker and Fukami 2014). Inhibitory priority effects might weaken under stressful conditions (Chase 2003;Tucker and Fukami 2014).…”

Historical contingency and spatial processes rather than ecological niche differentiation explain the distribution of invasive goldenrods (Solidago and Euthamia)

“…plant community composition of the new territory, specifically the presence of interacting species, availability of suitable space and resources, and the time a population has been established (Putten et al 2013;Vannette and Fukami 2014;Marchante et al 2015;Young et al 2015). Numerous studies of species' interactions indicate that the order of arrival into an ecosystem, the so-called priority effect (Shulman et al 1983), can influence local community assembly (Fukami 2010;Grman and Suding 2010;Kardol et al 2013;Putten et al 2013;Zefferman 2015;Fraser et al 2015). As a result, ecological contingencies can govern the success of colonisation of dispersing individuals and limit the distribution of invasive species (Ricklefs 2010;Fraser et al 2015).…”