Spatial division of labour of Schoenoplectus americanus

Abstract

If connected ramets are growing in heterogeneous environments, Division of Labour (DoL) among ramets potentially will result in more efficient sharing of resources and an overall benefit to the plants. As a result of DoL, connected ramets growing in a heterogeneous environment might achieve more biomass than ramets growing in a homogeneous environment. DoL has been demonstrated to occur in a few clonal plant species, although most studies simply focussed on biomass allocation, not on actual resource capturing such as water and nutrient consumption. The model system for our study is one in which two connected ramet groups of Schoenoplectus americanus were placed into contrasting environments. In one treatment, the connected ramets grew in heterogeneous environments and in the other treatment, the connected ramets grew in the same (i.e. homogeneous) environment. We manipulated two variables (light and salinity) in the experiment. We hypothesized that ramets growing in a shaded and fresh water condition in a heterogeneous environment would use more water than ramets growing in a similar condition but in a homogeneous environment. We further hypothesized that ramets growing in a light and saline condition in a heterogeneous environment would assimilate less water than ramets growing in a similar condition but in a homogeneous environment. These hypotheses are based on the assumption that ramets in a heterogeneous environment would translocate water from ramets growing in a shaded and fresh water condition to ramets growing in a light and saline water condition. We also hypothesized that ramets growing in heterogeneous environments achieve larger biomass than ramets in homogeneous environments. Ramets grown in light and saline conditions in heterogeneous environments allocated more biomass to aboveground parts, had taller shoots, larger Specific Green (leaf) Area and consumed less water than ramets grown in similar conditions but in a homogeneous environment. Results confirm the hypothesis that connected ramets in heterogeneous environments are specialised to capture locally abundant resources and share these with connected ramets growing in other habitats. The result of DoL is that the entire connected ramet system benefits and achieves higher biomass.

Do Clonal Plants Show Greater Division of Labour Morphologically and Physiologically at Higher Patch Contrasts?

“…This has been experimentally shown for Trifolium repens [7,8], Fragaria chiloensis [5], [6], [11], [12], Potentilla anserina [13], and P. reptans [14], Glechoma hederacea [15], [16], G. longituba [17], [18] and Schoenoplectus americanus [19]. These studies clearly showed the high potential benefits of division of labour to enhance resource capture of clonal plants and thereby to increase their performance in heterogeneous habitats compared to non-clonal plants.…”

Clonal integration facilitates the proliferation of smooth brome clones invading northern fescue prairies

“…Physiological integration between vegetatively connected ramets often facilitates the colonization of environments where parts of the clone experience contrasting conditions. Coastal dunes, deserts, and wetlands are often dominated by clonal perennials, whose vegetative connections permit the ''homogenization'' of patchy resources and the amelioration of environmental stress (Alpert 1996;Pennings and Callaway 2000;Ikegami et al 2008). Translocation between ramets supported the encroachment of smooth brome into adjacent prairies; however, sharing of resources with the mother clone inhibited the proliferation of ramets invading a nutrient-poor prairie.…”

“…The success of clonal species is often attributed to their capacity to share resources among individual subunits. Translocation of resources, including water, carbohydrates, and minerals (Alpert and Mooney 1986;Lau and Young 1988;Tissue and Nobel 1988;Stuefer and Hutchings 1994;Alpert 1996;Wijesinghe and Hutchings 1997;Kemball and Marshall 1995), enables clonal species to exploit patchy resources (Alpert and Mooney 1986;Wijesinghe and Hutchings 1997;Ikegami et al 2008), ameliorate environmental stress (Amsberry et al 2000;Pennings and Callaway 2000), and reduce the impacts of competition and herbivory (Hartnett and Bazzaz 1985;Schmid et al 1988).…”

Epigenetics: a potential mechanism for clonal plant success

“…For example, a genotype might forage across the landscape and develop modules that differentially specialize in the uptake of resources (reviewed in Hutchings and de Kroon 1994). As Wang et al (2011) point out, this has been experimentally shown for Trifolium repens (Stuefer et al 1996), Fragaria chiloensis (Roiloa et al 2007), Potentilla anserina (van Kleunen and Stuefer 1999), Potentilla reptans (Stuefer et al 1994), Glechoma hederacea (Birch and Hutchings 1994), Glechoma longituba (Chu et al 2006), and Schoenoplectus americanus (Ikegami et al 2008). …”