The importance of competition for light depends on productivity and disturbance.

Yann Hautier,Eva Vojtech,Andy Hector

doi:10.1002/ece3.4403

Yann Hautier, Eva Vojtech + Show 1 more

Open Access

https://doi.org/10.1002/ece3.4403

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Abstract

Eutrophication is a major cause of biodiversity loss. In grasslands, this appears to occur due to asymmetric competition for light following the increases in aboveground biomass production. Here, we report the results of an experiment with five grass species that tests how well‐competitive outcomes can be predicted under a factorial combination of fertilized and disturbed (frequent cutting) conditions. Under fertile conditions, our results confirm earlier success in predicting short‐term competitive outcomes based on light interception in monocultures. This effect was maintained but weakened under less fertile conditions with competition becoming more symmetric. However, under disturbed conditions, competitive outcomes could not be predicted from differences in light interception in monocultures regardless of fertility. Our results support the idea that competition in grasslands shifts from symmetric to asymmetric as fertility increases but that disturbance destroys this relationship, presumably by preventing the development of differences in canopy structure and reducing competition for light.

Highlights

Humans have greatly enhanced the rate of supply of nutrients worldwide (Galloway, Schlesinger, Levy, Michaels, & Schnoor, 1995; Tilman et al, 2001; Vitousek, Mooney, Lubchenco, & Melillo, 1997)
Our results demonstrate that size-asymmetric competition for light observed under fertile conditions is reduced at lower productivity and prevented by frequent disturbance of canopy development
Vojtech et al (2007, 2008) have shown that under productive conditions, short-term competitive outcomes could be well predicted by differences in the level of incident light intercepted in monoculture

Summary

| INTRODUCTION

Humans have greatly enhanced the rate of supply of nutrients worldwide (Galloway, Schlesinger, Levy, Michaels, & Schnoor, 1995; Tilman et al, 2001; Vitousek, Mooney, Lubchenco, & Melillo, 1997). Using a model system of five perennial grass species commonly found in European fertile grasslands, Vojtech et al (2007, 2008) investigated the short-term outcome of competition for light They performed two experiments under highly fertilized and irrigated conditions where light is assumed to be the limiting resource and competition for light to be important. Vojtech et al (2007) demonstrated that the differences in light intercepting ability conferred a disproportionate competitive advantage thereby confirming that under productive conditions competition between species for this resource is size asymmetric (Vojtech et al, 2007) Their experiments confirmed earlier reports of the importance of competition for light under productive conditions (Nord-Larsen, Damaard, & Weiner, 2006; Schwinning & Weiner, 1998; Weiner, 1990), they did not test for limitation by other potential resources. Our results demonstrate that size-asymmetric competition for light observed under fertile conditions is reduced at lower productivity and prevented by frequent disturbance of canopy development

| MATERIALS AND METHODS

Findings

| DISCUSSION