Physiological integration can increase competitive ability in clonal plants if competition is patchy

Area of Science:

• Ecology
• Plant Biology
• Evolutionary Biology

Background:

• Clonal plants, connected as ramets, often show increased fitness with differing resource supplies.
• Previous research has not directly investigated if physiological integration enhances interspecific competition in clonal plants.

Purpose of the Study:

• To test if physiological integration increases the competitive ability of clonal plants against a dominant grass species.
• To determine the role of competition spatial heterogeneity in the benefits of clonal integration.

Main Methods:

• Two- and four-ramet fragments of *Fragaria chiloensis* were grown with or without neighbors (*Bromus carinatus*).
• Connections between ramets were severed to prevent integration or left intact.
• Plant mass and leaf area were measured to assess competitive outcomes.

Main Results:

• Severing connections reduced leaf mass and area by 25% and total mass by 15% in two-ramet fragments when only one ramet had neighbors.
• Integration's positive effect on total mass was observed only when competition was spatially heterogeneous (one ramet competing).
• Severing connections had no significant effect on total mass when none or all ramets were grown with the grass.

Conclusions:

• This study provides the first direct evidence that physiological integration enhances clonal plant competitive ability under spatially heterogeneous competition.
• Integration may facilitate clonal plant establishment and persistence in diverse plant communities with fine-scale disturbances.
• Integration's benefits may be limited in uniformly dense communities dominated by taller species.