Architectural and growth traits differ in effects on performance of clonal plants: an analysis using a field‐parameterized simulation model

Abstract

Individual traits are often assumed to be linked in a straightforward manner to plant performance and processes such as population growth, competition and community dynamics. However, because no trait functions in isolation in an organism, the effect of any one trait is likely to be at least somewhat contingent on other trait values. Thus, to the extent that the suite of trait values differs among species, the magnitude and even direction of correlation between values of any particular trait and performance is likely to differ among species. Working with a group of clonal plant species, we assessed the degree of this contingency and therefore the extent to which the assumption of simple and general linkages between traits and performance is valid. To do this, we parameterized a highly calibrated, spatially explicit, individual-based model of clonal plant population dynamics and then manipulated one trait at a time in the context of realistic values of other traits for each species. The model includes traits describing growth, resource allocation, response to competition, as well as architectural traits that determine spatial spread. The model was parameterized from a short-term (3 month) experiment and then validated with a separate, longer term (two year) experiment for six clonal wetland sedges, Carex lasiocarpa, Carex sterilis, Carex stricta, Cladium mariscoides, Scirpus acutus and Scirpus americanus . These plants all co-occur in fens in southeastern Michigan and represent a spectrum of clonal growth forms from strong clumpers to runners with long rhizomes.Varying growth, allocation and competition traits produced the largest and most uniform responses in population growth among species, while variation in architectural traits produced responses that were smaller and more variable among species. This is likely due to the fact that growth and competition traits directly affect mean ramet size and number of ramets, which are direct components of population biomass. In contrast, architectural and allocation traits determine spatial distribution of biomass; in the long run, this also affects population size, but its net effect is more likely to be mediated by other traits. Such differences in how traits affect plant performance are likely to have implications for interspecific interactions and community structure, as well as on the interpretation and usefulness of single trait optimality models.Species traits are general, genetically determined characteristics of morphology and physiology. Such traits are often used in ecology to group species; these groups are then used to explain and predict community structure and dynamics (Grime et al.

Are competitive effect and response two sides of the same coin, or fundamentally different?

“…This finding is consistent with other studies (Goldberg & Fleetwood 1987;Gurevitch et al 1990;Keddy et al 2002), and is intuitive. Bigger plants usually have an advantage in capturing light (Grime 1977;Wildova et al 2007) Cahill 1999). We suggest the accumulation of evidence leads to a general conclusion that bigger plants are best able to suppress the growth of other plants when resources are in high supply.…”

“…2002), and is intuitive. Bigger plants usually have an advantage in capturing light (Grime 1977; Wildova et al. 2007) which is generally limiting under high nutrient conditions (Belcher, Keddy & Twolanstrutt 1995; Cahill 1999).…”

Can trait patterns along gradients predict plant community responses to climate change?

“…Perhaps, the capacity for rapid growth is not useful to new ramets vying for resources in grassland communities already packed with established individuals (but see: Wildová et al. ). Alternatively, SLA and leaf area may be poor predictors of growth in herbaceous species with photosynthetic stems.…”

“…That CWMs of architectural traits deviated from neutral expectations of community response while CWMs of growth-related traits (SLA, leaf area, lateral spread) did not, despite showing strong trends along spatial temperature gradients, is unexpected and interesting. Perhaps, the capacity for rapid growth is not useful to new ramets vying for resources in grassland communities already packed with established individuals (but see: Wildová et al 2007). Alternatively, SLA and ; the y-axis shows how that dissimilarity changed by 2013.…”

The effect of ramet mortality on clonal plant growth

“…However, without field studies, these do not yet provide a full picture of environmental controls and growth rules internal to the plant. A comprehensive study of this issue would be an interesting and important subject for future research (see a pioneering study by Wildová et al 2007).…”