Abstract:Disturbance can generate heterogeneous environments and profoundly influence plant diversity by creating patches at different successional stages. Herbivores, in turn, can govern plant succession dynamics by determining the rate of species replacement, ultimately affecting plant community structure. In a south-western Atlantic salt marsh, we experimentally evaluated the role of herbivory in the recovery following disturbance of the plant community and assessed whether herbivory affects the relative importance … Show more
“…; Kuijper & Bakker ; Daleo et al. ). Here we show that even in undisturbed patches herbivores can decrease dominance, positively affecting plant diversity.…”
Section: Discussionmentioning
confidence: 99%
“…; Daleo et al. ; Pascual et al. ) by consuming not only the dominant cordgrass S. densiflora but also other subordinate plant species (Vicari et al.…”
Question
Do herbivory and the presence of a dominant grass competitor interactively affect herbaceous communities and assembly rules in a SW Atlantic salt marsh?
Location
Upper salt marsh, Mar Chiquita coastal lagoon, Argentina.
Methods
We performed a field factorial experiment over 4 yr to evaluate the separate and interactive effects of (1) herbivory and (2) competition with the dominant grass species (i.e. Spartina densiflora) on the salt marsh subordinate plant community. The factorial design includes dominant grass removal and herbivory manipulation.
Results
Our results show that herbivory and presence of the dominant competitor interactively affect subordinate plant cover and diversity. Results further indicate that, in the presence of the dominant competitor, patch‐to‐patch variation in subordinate species composition is lower than expected at random, a result consistent with the expected outcomes of deterministic exclusion following light competition. Removal of the dominant grass nevertheless led to patch‐to‐patch dissimilarity in subordinate species composition, far from the dissimilarity expected at random, indicating increased importance of deterministic processes that drive communities to diverge.
Conclusion
Our results show that the conditional effect of herbivory on plant diversity can be determined by the presence of a single plant species. Dominant plant species, in addition, may not only affect plant species diversity by determining the number and identity of subordinate species in a given patch (i.e. α‐diversity) but also by affecting spatial variability through habitat homogenization.
“…; Kuijper & Bakker ; Daleo et al. ). Here we show that even in undisturbed patches herbivores can decrease dominance, positively affecting plant diversity.…”
Section: Discussionmentioning
confidence: 99%
“…; Daleo et al. ; Pascual et al. ) by consuming not only the dominant cordgrass S. densiflora but also other subordinate plant species (Vicari et al.…”
Question
Do herbivory and the presence of a dominant grass competitor interactively affect herbaceous communities and assembly rules in a SW Atlantic salt marsh?
Location
Upper salt marsh, Mar Chiquita coastal lagoon, Argentina.
Methods
We performed a field factorial experiment over 4 yr to evaluate the separate and interactive effects of (1) herbivory and (2) competition with the dominant grass species (i.e. Spartina densiflora) on the salt marsh subordinate plant community. The factorial design includes dominant grass removal and herbivory manipulation.
Results
Our results show that herbivory and presence of the dominant competitor interactively affect subordinate plant cover and diversity. Results further indicate that, in the presence of the dominant competitor, patch‐to‐patch variation in subordinate species composition is lower than expected at random, a result consistent with the expected outcomes of deterministic exclusion following light competition. Removal of the dominant grass nevertheless led to patch‐to‐patch dissimilarity in subordinate species composition, far from the dissimilarity expected at random, indicating increased importance of deterministic processes that drive communities to diverge.
Conclusion
Our results show that the conditional effect of herbivory on plant diversity can be determined by the presence of a single plant species. Dominant plant species, in addition, may not only affect plant species diversity by determining the number and identity of subordinate species in a given patch (i.e. α‐diversity) but also by affecting spatial variability through habitat homogenization.
“…2012; Daleo et al. 2014), including cascading effects of top predator presence and identity on consumers and plants (Silliman and Bertness 2002; Kimbro 2012; Bertness et al. 2014).…”
The importance of intraspecific variation has emerged as a key question in community ecology, helping to bridge the gap between ecology and evolution. Although much of this work has focused on plant species, recent syntheses have highlighted the prevalence and potential importance of morphological, behavioral, and life history variation within animals for ecological and evolutionary processes. Many small-bodied consumers live on the plant that they consume, often resulting in host plant-associated trait variation within and across consumer species. Given the central position of consumer species within tritrophic food webs, such consumer trait variation may play a particularly important role in mediating trophic dynamics, including trophic cascades. In this study, we used a series of field surveys and laboratory experiments to document intraspecific trait variation in a key consumer species, the marsh periwinkle Littoraria irrorata, based on its host plant species (Spartina alterniflora or Juncus roemerianus) in a mixed species assemblage. We then conducted a 12-week mesocosm experiment to examine the effects of Littoraria trait variation on plant community structure and dynamics in a tritrophic salt marsh food web. Littoraria from different host plant species varied across a suite of morphological and behavioral traits. These consumer trait differences interacted with plant community composition and predator presence to affect overall plant stem height, as well as differentially alter the density and biomass of the two key plant species in this system. Whether due to genetic differences or phenotypic plasticity, trait differences between consumer types had significant ecological consequences for the tritrophic marsh food web over seasonal time scales. By altering the cascading effects of the top predator on plant community structure and dynamics, consumer differences may generate a feedback over longer time scales, which in turn influences the degree of trait divergence in subsequent consumer populations.
“…A great part of the salt marsh C stock is belowground, in the form of living roots or nonliving litter; thus, belowground biomass allocation patterns, along with total primary production, are the main plant traits that regulate soil C sequestration (De Deyn et al 2008). Seed availability, in addition, can determine salt marsh plant composition at patch size (Rand 2000), which would have important consequences, particularly for bare patch dynamics (e.g., Daleo et al 2014), and thus, system functioning. Changes in stem density and internode length drive changes in how densely packed stems are, affecting water flow, sediment stabilization and retention, evaporation, and sediment salinity, as well as refuge availability to invertebrate animals (Brusati and Grosholz 2006).…”
Bottom-up and top-down effects act together to exert strong control over plant growth and reproduction, but how physical stress modifies those interactive forces remains unclear. Even though empirical evidence is scarce, theory predicts that the importance of both top-down- and bottom-up forces may decrease as physical stress increases. Here, we experimentally evaluate in the field the separate and interactive effect of salinity, nutrient availability, and crab herbivory on plant above- and belowground biomass, as well as on sexual and clonal reproduction in the salt marsh plant Spartina densiflora. Results show that the outcome of the interaction between nutrient availability and herbivory is highly context dependent, not only varying with the abiotic context (i.e., with or without increased salinity stress), but also with the dependent variable considered. Contrary to theoretical predictions, our results show that, consistently across different measured variables, salinity stress did not cancel bottom-up (i.e., nutrients) or top-down (i.e., consumers) control, but has additive effects. Our results support emerging theory by highlighting that, under many conditions, physical stress can act additively with, or even stimulate, consumer control, especially in cases where the physical stress is only experienced by basal levels of the trophic chain. Abiotic stress, as well as bottom-up and top-down factors, can affect salt marsh structure and function not only by affecting biomass production but also by having other indirect effects, such as changing patterns in plant biomass allocation and reproduction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.