The Stoichiometry of Nutrient Release by Terrestrial Herbivores and Its Ecosystem Consequences

Sitters, Judith; Bakker, Elisabeth S.; Veldhuis, Michiel P.; Veen, G. F.; Venterink, Harry Olde; Vanni, Michael J.

doi:10.3389/feart.2017.00032

Cited by 60 publications

(67 citation statements)

References 96 publications

(133 reference statements)

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“…In accordance with our hypotheses, heavy and long‐term grazing by reindeer promoted P limitation of above‐ground primary production (Figures and ). Only a few studies have addressed the effects of herbivores on nutrient limitation of vegetation in terrestrial ecosystems (Sitters et al, ). Corresponding to our results, two previous studies also revealed that long‐term, heavy grazing by large herbivores has the potential to promote P limitation using data on plant N:P ratios.…”

Section: Discussionmentioning

confidence: 99%

“…It is well known that herbivores influence nutrient cycling and availability in soils through several pathways, such as returning nutrients in the form of dung and urine, altering plant community composition and litter quality, and/or influencing physical properties, such as soil porosity (Bardgett & Wardle, ; Schrama et al, ; Sitters & Olde Venterink, ). Herbivores thus have the potential to change the availability of plant nutrients, such as nitrogen (N) and phosphorus (P) (Sitters et al, ). Since N and/or P commonly limit plant growth (Aerts & Chapin, ; Elser et al, ), herbivore‐induced changes in soil N:P stoichiometry are likely to affect plant nutrient limitation and productivity (Sitters et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Long‐term heavy reindeer grazing promotes plant phosphorus limitation in arctic tundra

et al. 2019

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The potential of large mammalian herbivores to shift plant communities between nitrogen (N) and phosphorus (P) limitation has received little attention so far. However, herbivores can influence the cycling of these growth‐limiting nutrients, and thereby affect plant nutrient limitation and productivity. Tundra ecosystems are nutrient‐poor and commonly grazed by large herbivores like reindeer and may thus be responsive to such changes. Here, we examined the effect of long‐term light and heavy reindeer grazing on nutrient limitation of plant growth in a Scandinavian arctic tundra. We are the first to conduct a factorial N and P fertilization experiment across the two grazing regimes in two functionally contrasting vegetation types: heath and meadow. Annual primary productivity (APP) showed contrasting responses to our fertilization treatments under light and heavy grazing. Under light grazing, APP increased in response to N + P additions in both the heath and meadow. Under heavy grazing, APP increased in response to N in the heath, with an additional positive effect of N + P combined, while APP increased in response to P and N + P additions in the meadow. These results clearly show that an increase in the grazing intensity of reindeer facilitated a shift towards more P‐limited conditions in Scandinavian arctic tundra, by increasing N cycling without having a corresponding positive effect on P cycling. In the N‐poor heath, reindeer increased soil N availability at least partly due to a shift towards more N‐rich graminoids, while in the meadow, reindeer decreased soil P availability. The mechanisms behind this decrease remain unclear, but reindeer may simply export more P from the system than N due to their large P demand for the production of their antlers. Synthesis. We conclude that heavy and long‐term reindeer grazing promoted a more P‐limited tundra, thus experimentally confirming the potential of large mammalian herbivores to influence nutrient limitation of plant growth. A plain language summary is available for this article.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Long‐term heavy reindeer grazing promotes plant phosphorus limitation in arctic tundra

et al. 2019

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“…Research in animal-mediated organic matter transformation highlights the controls on (Allgeier, Wenger, Rosemond, Schindler, & Layman, 2015;Vanni & McIntyre, 2016) and ecosystem effects of (Atkinson et al, 2017;Metcalfe et al, 2014;Sitters et al, 2017) inorganic nutrient recycling. As such, animal influences on inorganic nutrient cycling are more effectively integrated into biogeochemical and food web models than are animal-mediated impacts on organic nutrient dynamics and the flow of energy (Atkinson et al, 2017;Zou et al, 2016).…”

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Animal‐mediated organic matter transformation: Aquatic insects as a source of microbially bioavailable organic nutrients and energy

et al. 2018

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Animal communities are essential drivers of energy and elemental flow in ecosystems. However, few studies have investigated the functional role of animals as sources of dissolved organic matter (DOM) and the subsequent utilization of that DOM by the microbial community. In a small forested headwater stream, we tested the effects of taxonomy, feeding traits, and body size on the quality and quantity of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) excreted by aquatic insects. In addition, we conducted steady‐state solute additions to estimate instream demand for labile C and compared it to the C excreted by invertebrates. Individual excretion rates and excretion composition varied with body size, taxonomy and feeding guild. The estimated average community excretion rate was 1.31 μg DOC· per mg insect dry weight (DW)−1 hr−1 and 0.33 μg DON·mg DW−1 hr‐1, and individuals excreted DON at nearly twice the rate of NH4+. This DOM was 2–5 times more bioavailable to microbial heterotrophs than ambient stream water DOM. We estimated that the insect community, conservatively, excreted 1.62 mg of bioavailable DOC·m−2 hr−1 and through steady‐state additions measured an ambient labile C demand as 3.97 ± 0.67 mg C m−2 hr−1. This suggests that insect‐mediated transformation and excretion of labile DOC could satisfy a significant fraction (40 ± 7%) of labile C demand in this small stream. Collectively, our results suggest that animal excretion plays an essential functional role in transforming organic matter into microbially bioavailable forms and may satisfy a variable but significant portion of microbial demand for labile C and N. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13242/suppinfo is available for this article.

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“…The importance of animal-mediated nutrient cycling is now widely accepted across ecosystems (Allgeier, Burkepile, & Layman, 2017;Atkinson, Capps, Rugenski, & Vanni, 2017;Sitters et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought

et al. 2019

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1. Animals contribute significantly to nutrient cycling through excretion, but most studies consider their effects under relatively benign abiotic conditions. Disturbances such as drought may alter animals' nutrient contributions through shifts in species composition and biomass. Headwater streams are particularly vulnerable to extreme climate events and thus might show rapid changes in stream biota and their ecosystem effects.2. We tested how biomass and subsequent ecosystem effects (nutrient cycling) of an intermittent prairie stream community changed during a drought. We quantified the biomass and contributions to nutrient cycling for assemblages comprising fishes, crayfish, and tadpoles in 12 isolated pools over 3 months encompassing the harshest drought on record for Kings Creek, KS, U.S.A. We predicted that macroconsumer biomass would decline with pool surface area and that differences in macroconsumer biomass and taxonomic composition would lead to different contributions of pool assemblages to nutrient cycling.3. The biomass of pool assemblages declined with decreasing pool size, a pattern apparently driven by mortality, emigration, or metamorphosis. We also observed a change in assemblage structure of drying pools during drought relative to pool size, shifting dominance toward species with more drought-resistant traits.Accordingly, assemblage nitrogen (N) excretion rates declined as pool biomass was reduced, leading to a 58% reduction in N available to epilithic biofilms. Phosphorus (P) excretion rates declined from June to July, but increased in August, as species with high P excretion rates maintained similar proportional biomass and biomass of a non-native fish increased. Molar N:P of pool assemblage excretion declined significantly throughout the drought and coincided with loss of southern redbelly dace (Chrosomus erythrogaster: Cyprinidae). 4. Animal-mediated nutrient cycling was altered by the loss of biomass and stoichiometric traits of taxa that differed in their occurrences and ability to tolerate abiotic conditions during drought. Elevated availability of dissolved N in isolated pools may increase N uptake rates by biofilms during drought conditions, indicating the importance of N excreted by aggregated macroconsumers, especially those with S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Hopper GW, Gido KB, Pennock CA, et al. Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought.

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The Stoichiometry of Nutrient Release by Terrestrial Herbivores and Its Ecosystem Consequences

Cited by 60 publications

References 96 publications

Long‐term heavy reindeer grazing promotes plant phosphorus limitation in arctic tundra

Long‐term heavy reindeer grazing promotes plant phosphorus limitation in arctic tundra

Animal‐mediated organic matter transformation: Aquatic insects as a source of microbially bioavailable organic nutrients and energy

Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought

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