Spatial division of labour of Schoenoplectus americanus

Forest Research Alice Holt Lodge Wrecclesham, Farnham Surrey GU10 4LH UK
Plant Ecology (Impact Factor: 1.64). 11/2008; 199(1):55-64. DOI: 10.1007/s11258-008-9411-4
Source: OAI

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.

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