Herbivore species identity mediates interspecific competition between plants

Abstract

Herbivory is a major driver of plant communities. Most herbivores preferentially consume dominant species and slow down plant succession, but it remains unclear in which ways different herbivore species have contrasting effects on plant communities. In this study, we investigated the extent to which closely related insect herbivores with slight differences in their feeding behaviour induce contrasting reactions in plant communities. We studied the impact of herbivory by two Gomphocerinae grasshopper species, Chorthippus scalaris and Euthystira brachyptera, on the outcome of competition between the plant species Dactylis glomerata and Festuca paniculata. Under a controlled choice experiment, C. scalaris preferentially consumed D. glomerata while E. brachyptera preferred F. paniculata, but in an experimental plant community (mesocosm) both species consumed the plant species proportionally to their abundance and the amount of herbivory marks detected on the leaves did not depend on the specific grasshopper species. The herbivory pressure of both grasshopper species significantly reduced the vegetative height and the number of tillers of F. paniculata, with C. scalaris showing a stronger effect. As a consequence, herbivory by E. brachyptera did not significantly affect interspecific plant competition, whereas C. scalaris enhanced the dominance of D. glomerata. Our study shows that closely related herbivores that only slightly differ in their feeding behaviour can induce contrasting effects on interspecific plant competition, and that the dominant species D. glomerata is more tolerant to herbivory than F. paniculata. The specific plant and herbivore traits responsible for contrasting herbivory effects on plant competition remains to be explored.Nomenclature: Fournier (2001) for higher plants and Baur et al. (2006) for grasshoppers.

Effect of tall-grass invasion on the flowering-related functional pattern of submediterranean hay-meadows

“…It is well documented that the floristic composition and variability of pastures are strongly related both to the spatial variation of environmental features and constraints (Catorci & Gatti 2010;Blasi et al 2012;Ribeiro et al 2013) and to the management type (Catorci et al 2012c;Ibanez et al 2013). Moreover, abandonment of farming activities leads to the reduction of landscape complexity and promotes vegetation dynamics processes, a factor that could be detrimental for the conservation of biodiversity (Gargano et al 2012).…”

Size‐selective exclusion of mammals and invertebrates differently affects grassland plant communities depending on vegetation type

“…Many grass species have a superior ability to exploit soil nutrients (Firn et al., 2017; Risch et al., 2015), and can increase the number of tillers when the grazing pressure is lowered (i.e. clonal growth ability; Firn et al., 2017; Ibanez et al., 2013). Clonal growth is an important factor influencing plant assembly (Benot et al., 2011), vegetation structure and stability in grassland ecosystems (see Dong et al., 2015).…”

“…Therefore, also the loss of these smaller mammals can have a large impact on plant communities (Andersson & Jonasson, 1986; Weltzin et al., 1997; Davidson et al., 2010; also see references in Bakker et al., 2006). Finally, also invertebrates play important ecological roles in grassland ecosystems (Curry, 1994; Ibanez et al., 2013). Similar to mammals they can accelerate nutrient cycling as they produce considerable amounts of grass and drop large amounts of leave fractions to the soil surface rather than consuming them (Curry, 1994).…”

Aphid herbivory as a potential driver of primary succession in coastal dunes

“…The main underlying mechanism is the differential impact of herbivory on different plant species. That is, insect herbivores show varying host-plant preferences; different host plants in turn show variable tolerances or resistance to the herbivores (Choeni and Sebata 2014;Ibanez et al 2013;Kuijper et al 2010;Strauss and Agrawal 1999). By means of such variation in herbivory and tolerance, herbivores determine interspecific competition and influence productivity, species diversity, evenness and composition within the community (Allan and Crawley 2011;Stein et al 2010;Hillebrand et al 2007;Maron and Crone 2006).…”

“…Succession is a sequential change in relative abundances of the dominant plant species in a community (Huston and Smith 1987). Consequently, herbivores have the power to drive (or halt) plant succession if they influence the competitive abilities of early successional plant species relative to later successional plant species (Ibanez et al 2013;Karlsen et al 2013;Bach 2001).…”