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Title: Genetic Based Plant Resistance and Susceptibility Traits to Herbivory Influence Needle and Root Litter Nutrient Dynamics

Abstract

It is generally assumed that leaf and root litter decomposition have similar drivers and that nutrient release from these substrates is synchronized. Few studies have examined these assumptions, and none has examined how plant genetics (i.e., plant susceptibility to herbivory) could affect these relationships. Here we examine the effects of herbivore susceptibility and resistance on needle and fine root litter decomposition of pi on pine, Pinus edulis. The study population consists of individual trees that are either susceptible or resistant to herbivory by the pi on needle scale, Matsucoccus acalyptus, or the stem-boring moth, Dioryctria albovittella. Genetic analyses and experimental removals and additions of these insects have identified trees that are naturally resistant and susceptible to these insects. These herbivores increase the chemical quality of litter inputs and alter soil microclimate, both of which are important decomposition drivers. Our research leads to four major conclusions: Herbivore susceptibility and resistance effects on 1) needle litter mass loss and phosphorus (P) retention in moth susceptible and resistant litter are governed by microclimate, 2) root litter nitrogen (N) and P retention, and needle litter N retention are governed by litter chemical quality, 3) net nutrient release from litter can reverse over time, 4)more » root and needle litter mass loss and nutrient release are determined by location (above- vs. belowground), suggesting that the regulators of needle and root decomposition differ at the local scale. Understanding of decomposition and nutrient retention in ecosystems requires consideration of herbivore effects on above- and belowground processes and how these effects may be governed by plant genotype. Because an underlying genetic component to herbivory is common to most ecosystems of the world and herbivory may increase in climatic change scenarios, it is important to evaluate the role of plant genetics in affecting carbon and nutrient fluxes.« less

Authors:
 [1];  [2];  [3];  [3];  [3]
  1. ORNL
  2. Smithsonian Environmental Research Center, Edgewater, MD
  3. Northern Arizona University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931958
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Ecology; Journal Volume: 95; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 54 ENVIRONMENTAL SCIENCES; CARBON; CLIMATIC CHANGE; ECOSYSTEMS; GENETICS; GENOTYPE; INSECTS; MOTHS; NITROGEN; NUTRIENTS; PHOSPHORUS; RETENTION; SOILS; SUBSTRATES; TREES; decomposition; genotype; herbivory; insects; needles; nitrogen; nutrient cycling

Citation Formats

Classen, Aimee T, Chapman, Samantha K., Whitham, Thomas G, Hart, Stephen C, and Koch, George W. Genetic Based Plant Resistance and Susceptibility Traits to Herbivory Influence Needle and Root Litter Nutrient Dynamics. United States: N. p., 2007. Web. doi:10.1111/j.1365-2745.2007.01297.x.
Classen, Aimee T, Chapman, Samantha K., Whitham, Thomas G, Hart, Stephen C, & Koch, George W. Genetic Based Plant Resistance and Susceptibility Traits to Herbivory Influence Needle and Root Litter Nutrient Dynamics. United States. doi:10.1111/j.1365-2745.2007.01297.x.
Classen, Aimee T, Chapman, Samantha K., Whitham, Thomas G, Hart, Stephen C, and Koch, George W. Mon . "Genetic Based Plant Resistance and Susceptibility Traits to Herbivory Influence Needle and Root Litter Nutrient Dynamics". United States. doi:10.1111/j.1365-2745.2007.01297.x.
@article{osti_931958,
title = {Genetic Based Plant Resistance and Susceptibility Traits to Herbivory Influence Needle and Root Litter Nutrient Dynamics},
author = {Classen, Aimee T and Chapman, Samantha K. and Whitham, Thomas G and Hart, Stephen C and Koch, George W},
abstractNote = {It is generally assumed that leaf and root litter decomposition have similar drivers and that nutrient release from these substrates is synchronized. Few studies have examined these assumptions, and none has examined how plant genetics (i.e., plant susceptibility to herbivory) could affect these relationships. Here we examine the effects of herbivore susceptibility and resistance on needle and fine root litter decomposition of pi on pine, Pinus edulis. The study population consists of individual trees that are either susceptible or resistant to herbivory by the pi on needle scale, Matsucoccus acalyptus, or the stem-boring moth, Dioryctria albovittella. Genetic analyses and experimental removals and additions of these insects have identified trees that are naturally resistant and susceptible to these insects. These herbivores increase the chemical quality of litter inputs and alter soil microclimate, both of which are important decomposition drivers. Our research leads to four major conclusions: Herbivore susceptibility and resistance effects on 1) needle litter mass loss and phosphorus (P) retention in moth susceptible and resistant litter are governed by microclimate, 2) root litter nitrogen (N) and P retention, and needle litter N retention are governed by litter chemical quality, 3) net nutrient release from litter can reverse over time, 4) root and needle litter mass loss and nutrient release are determined by location (above- vs. belowground), suggesting that the regulators of needle and root decomposition differ at the local scale. Understanding of decomposition and nutrient retention in ecosystems requires consideration of herbivore effects on above- and belowground processes and how these effects may be governed by plant genotype. Because an underlying genetic component to herbivory is common to most ecosystems of the world and herbivory may increase in climatic change scenarios, it is important to evaluate the role of plant genetics in affecting carbon and nutrient fluxes.},
doi = {10.1111/j.1365-2745.2007.01297.x},
journal = {Journal of Ecology},
number = 6,
volume = 95,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • 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.more » 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.« less
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  • Morphological responses of the root system were tested by assessing scale, precision, discrimination, and sensitivity. Observations of high variation between species in scale, precision and sensitivity. In herbaceous species alone, scale and precision were positively correlated. Sensitivity was not closely related to precision, indicating that proliferation of roots in fertile patches does not always yield growth benefits in heterogeneous soils. Plant life form was not correlated with precision or sensitivity; however, scale of response was greater in herbs than in woody plants-possibly due to different root growth rates.
  • Plant-insect interactions can alter ecosystem processes, especially if the insects modify plant architecture, quality, or the quantity of leaf litter inputs. In this study, we investigated the interactions between the gall midge Rhopalomyia solidaginis and tall goldenrod, Solidago altissima, to quantify the degree to which the midge alters plant architecture and how the galls affect rates of litter decomposition and nutrient release in an old-field ecosystem. R. solidaginis commonly leads to the formation of a distinct apical rosette gall on S. altissima and approximately 15% of the ramets in a S. altissima patch were galled (range: 3-34%). Aboveground biomass ofmore » galled ramets was 60% higher and the leaf area density was four times greater on galled leaf tissue relative to the portions of the plant that were not affected by the gall. Overall decomposition rate constants did not differ between galled and ungalled leaf litter. However, leaf-litter mass loss was lower in galled litter relative to ungalled litter, which was likely driven by modest differences in initial litter chemistry; this effect diminished after 12 weeks of decomposition in the field. The proportion of N remaining was always higher in galled litter than in ungalled litter at each collection date indicating differential release of nitrogen in galled leaf litter. Several studies have shown that plant-insect interactions on woody species can alter ecosystem processes by affecting the quality or quantity of litter inputs. Our results illustrate how plant-insect interactions in an herbaceous species can affect ecosystem processes by altering the quality and quantity of litter inputs. Given that S. altissima dominates fields and roadsides and that R. solidaginis galls are highly abundant throughout eastern North America, these interactions are likely to be important for both the structure and function of old-field ecosystems.« less
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