Patterns in soil fertility and root herbivory interact to influence fine-root dynamics

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Date

2006-03

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Publisher

Ecological Society of America

Abstract

Fine-scale soil nutrient enrichment typically stimulates root growth, but it may also increase root herbivory, resulting in trade-offs for plant species and potentially influencing carbon cycling patterns. We used root ingrowth cores to investigate the effects of microsite fertility and root herbivory on root biomass in an aggrading upland forest in the coastal plain of South Carolina, USA. Treatments were randomly assigned to cores from a factorial combination of fertilizer and insecticide. Soil, soil fauna, and roots were removed from the cores at the end of the experiment (8-9 mo), and roots were separated at harvest into three diameter classes. Each diameter class responded differently to fertilizer and insecticide treatments. The finest roots (< 1.0 mm diameter), which comprised well over half of all root biomass, were the only ones to respond significantly to both treatments, increasing when fertilizer and when insecticide were added (each P < 0.0001), with maximum biomass found where the treatments were combined (interaction term significant, P < 0.001). These results Suggest that root-feeding insects have a strong influence on root standing crop with stronger herbivore impacts on finer roots and within more fertile microsites. Thus, increased vulnerability to root herbivory is a potentially significant,cost of root foraging in nutrient-rich patches.

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Keywords

elateridae, heterogeneity, root foraging, root ingrowth core, scarabaeidae, early plant succession, bottom-up forces, insect herbivory, top-down, nutrient heterogeneity, community structure, tallgrass prairie, spatial, variation, united-states, responses

Citation

Glen N. Stevens and Robert H. Jones 2006. PATTERNS IN SOIL FERTILITY AND ROOT HERBIVORY INTERACT TO INFLUENCE FINE-ROOT DYNAMICS. Ecology 87:616-624. http://dx.doi.org/10.1890/05-0809