Trunk cutting initiates bottom‐up cascades in a tri‐trophic system: sprouting increases biodiversity of herbivorous and predaceous arthropods on willows

Abstract

T. 2006. Trunk cutting initiates bottom-up cascades in a tri-trophic system: sprouting increases biodiversity of herbivorous and predaceous arthropods on willows. Á/ Oikos 113: 259 Á/268.We examined the effects of trunk cutting on the regrowth responses of two dominant willow species, Salix eriocarpa and S. gilgiana , and the subsequent effects on the community structure (abundance and species richness) of herbivorous and predaceous arthropods. We studied ten randomly selected pairs of cut and uncut (control) trees of each willow species. Field observations showed that when the trunks were cut, shoots sprouted from the base and developed rapidly. These shoots continued to grow until July, producing lateral shoots and leaves, whereas current-year shoots on uncut trees essentially stopped growing by April. In July, the upper leaves of cut trees were less tough and had a greater water and nitrogen content than leaves of uncut trees. Leaf consumption and abundance and species richness of both herbivorous and predaceous arthropods were significantly greater on cut trees than on uncut trees in both willow species. Overall, trunk cutting resulted in at least a two-fold increase in both relative abundance and species richness within the arthropod community on the willow species. We concluded that the severe physical damage caused by trunk cutting greatly increased the biodiversity of herbivorous and predaceous arthropods through bottom-up cascading effects.

Separating ontogenetic and environmental determination of resistance to herbivory in cottonwood

“…When selection imposed Nakamura et al 2006). In this study, we use Populus angustifolia trees propagated from cuttings to disentangle stable, genetically programmed effects from environmentally influenced effects on developmental variation in resistance to the aphid, Pemphigus betae.…”

Bottom‐up multitrophic effects in resprouting plants

“…Plant changes in response to aboveground tissue loss may differentially impact the herbivore community and its associated natural enemies. There is a growing number of studies reporting that resprouting affects the abundance and efficacy of natural enemies (Nakamura et al 2006, Utsumi et al 2009, and yet none have addressed if this effect is direct through changes in plant traits or indirectly by differences in herbivore density, diversity, and composition. Chromolaena pungens (Gardner) R. King and H. Rob.…”

“…Rapid plant regrowth following mammalian browsing and fire often increases tissue nutritional content, decreases chemical or physical defenses, alters morphology, phenology, and reproduction of plants (Maschinski and Whitham 1989, Strauss and Agrawal 1999, Spiller and Agrawal 2003, Sharaf and Price 2004, Nakamura et al 2006. Resprouts tend to have higher nutritional quality and often are less defended, which makes them more susceptible to chewing herbivores (Danell and Huss-Danell 1985, Spiller and Agrawal 2003, Nakamura et al 2006, Utsumi et al 2009).…”

“…Resprouts tend to have higher nutritional quality and often are less defended, which makes them more susceptible to chewing herbivores (Danell and Huss-Danell 1985, Spiller and Agrawal 2003, Nakamura et al 2006, Utsumi et al 2009). On the contrary, resprouting plants are avoided or are less consumed when resprouted tissue offers herbivores lower food quality, higher resistance, or a reduced number of niches for their establishment Forkner 1999, Bailey andWhitham 2003).…”

“…We used a manipulative field experiment to test the hypotheses that clipping-induced resprouting and nutrient availability, separately and in combination, would (1) influence plant traits, (2) benefit chewing herbivores, sap-suckers, gallers, and pre-dispersal seed predators, and (3) cascade up to the third trophic level by positively affecting herbivores. Clippinginduced regrowth is expected to increase foliage quality, which is likely to benefit herbivores (Price 1991, Nakamura et al 2006, increasing leaf and flower head herbivory, as well as the density and species richness of herbivores. Resprouting will indirectly increase the abundance of predators and parasitoids via increased numbers or richness of herbivores (Hunter and Price 1992).…”