Limits...
Herbivory and Stoichiometric Feedbacks to Primary Production.

Krumins JA, Krumins V, Forgoston E, Billings L, van der Putten WH - PLoS ONE (2015)

Bottom Line: In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants.We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant.This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Molecular Biology, Montclair State University, Montclair, New Jersey, United States of America; Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands.

ABSTRACT
Established theory addresses the idea that herbivory can have positive feedbacks on nutrient flow to plants. Positive feedbacks likely emerge from a greater availability of organic carbon that primes the soil by supporting nutrient turnover through consumer and especially microbially-mediated metabolism in the detrital pool. We developed an entirely novel stoichiometric model that demonstrates the mechanism of a positive feedback. In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants. The model consists of differential equations coupling flows among pools of: plants, herbivores, detrital carbon and nitrogen, and inorganic nitrogen. We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant. Our model analyses show that partial feeding and plant C:N interact because when herbivores are sloppy and plant biomass is diverted to the detrital pool, more mineral nitrogen is available to plants because of the stoichiometric difference between the organisms in the detrital pool and the herbivore. This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production.

No MeSH data available.


The steady state coexistence solution of the pools as a function of herbivore efficiency, a. detrital carbon, b. detrital nitrogen, c. herbivore biomass carbon, d. inorganic nitrogen and e. plant biomass carbon and f. plant biomass nitrogen.In all panels, asterisks indicate CNP = 20, triangles indicate CNP = 30 and diamonds indicate CNP = 40.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4476572&req=5

pone.0129775.g002: The steady state coexistence solution of the pools as a function of herbivore efficiency, a. detrital carbon, b. detrital nitrogen, c. herbivore biomass carbon, d. inorganic nitrogen and e. plant biomass carbon and f. plant biomass nitrogen.In all panels, asterisks indicate CNP = 20, triangles indicate CNP = 30 and diamonds indicate CNP = 40.

Mentions: The goal of this work was to resolve the mechanisms through which herbivory can be beneficial to plant growth. We explore the idea that the benefits of herbivory would vary depending whether nutrients are mineralized through the herbivore or the detrital pools with respect to the stoichiometric quality of the plant grazed. The results show that when e1 is low, the amount of detrital carbon and nitrogen present in soil increases, and therefore the proportion of plant biomass mineralized in the detrital pool as opposed to the herbivore pool increases. The availability of detrital carbon (Fig 2a) is highest when e1 is very low and the C:N of the plant is high, and the difference between available detrital carbon from plants of low C:N and those from high C:N declines with increasing e1. Intuitively, the reverse is true for detrital nitrogen (Fig 2b) in that more is available when plant C:N is lowest, but again, this interacts with e1. We see that when e1 is greatest, herbivore biomass is greatest (Fig 2c), and that this interacts with plant stoichiometry in that herbivore biomass is greatest when they consume high C:N plants, but this difference decreases as e1 increases. The availability of inorganic nitrogen for plant uptake increases as herbivore e1 increases (Fig 2d). It follows that inorganic nitrogen availability is highest at more complete herbivore feeding (high e1) because plant biomass (Fig 2e and 2f), and therefore plant uptake (Fig 3d), are lower. Plant biomass nitrogen is lower because herbivore biomass is higher (Fig 2c); This difference is most pronounced when plant C:N is lowest (Fig 2f).


Herbivory and Stoichiometric Feedbacks to Primary Production.

Krumins JA, Krumins V, Forgoston E, Billings L, van der Putten WH - PLoS ONE (2015)

The steady state coexistence solution of the pools as a function of herbivore efficiency, a. detrital carbon, b. detrital nitrogen, c. herbivore biomass carbon, d. inorganic nitrogen and e. plant biomass carbon and f. plant biomass nitrogen.In all panels, asterisks indicate CNP = 20, triangles indicate CNP = 30 and diamonds indicate CNP = 40.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4476572&req=5

pone.0129775.g002: The steady state coexistence solution of the pools as a function of herbivore efficiency, a. detrital carbon, b. detrital nitrogen, c. herbivore biomass carbon, d. inorganic nitrogen and e. plant biomass carbon and f. plant biomass nitrogen.In all panels, asterisks indicate CNP = 20, triangles indicate CNP = 30 and diamonds indicate CNP = 40.
Mentions: The goal of this work was to resolve the mechanisms through which herbivory can be beneficial to plant growth. We explore the idea that the benefits of herbivory would vary depending whether nutrients are mineralized through the herbivore or the detrital pools with respect to the stoichiometric quality of the plant grazed. The results show that when e1 is low, the amount of detrital carbon and nitrogen present in soil increases, and therefore the proportion of plant biomass mineralized in the detrital pool as opposed to the herbivore pool increases. The availability of detrital carbon (Fig 2a) is highest when e1 is very low and the C:N of the plant is high, and the difference between available detrital carbon from plants of low C:N and those from high C:N declines with increasing e1. Intuitively, the reverse is true for detrital nitrogen (Fig 2b) in that more is available when plant C:N is lowest, but again, this interacts with e1. We see that when e1 is greatest, herbivore biomass is greatest (Fig 2c), and that this interacts with plant stoichiometry in that herbivore biomass is greatest when they consume high C:N plants, but this difference decreases as e1 increases. The availability of inorganic nitrogen for plant uptake increases as herbivore e1 increases (Fig 2d). It follows that inorganic nitrogen availability is highest at more complete herbivore feeding (high e1) because plant biomass (Fig 2e and 2f), and therefore plant uptake (Fig 3d), are lower. Plant biomass nitrogen is lower because herbivore biomass is higher (Fig 2c); This difference is most pronounced when plant C:N is lowest (Fig 2f).

Bottom Line: In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants.We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant.This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Molecular Biology, Montclair State University, Montclair, New Jersey, United States of America; Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands.

ABSTRACT
Established theory addresses the idea that herbivory can have positive feedbacks on nutrient flow to plants. Positive feedbacks likely emerge from a greater availability of organic carbon that primes the soil by supporting nutrient turnover through consumer and especially microbially-mediated metabolism in the detrital pool. We developed an entirely novel stoichiometric model that demonstrates the mechanism of a positive feedback. In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants. The model consists of differential equations coupling flows among pools of: plants, herbivores, detrital carbon and nitrogen, and inorganic nitrogen. We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant. Our model analyses show that partial feeding and plant C:N interact because when herbivores are sloppy and plant biomass is diverted to the detrital pool, more mineral nitrogen is available to plants because of the stoichiometric difference between the organisms in the detrital pool and the herbivore. This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production.

No MeSH data available.