The effects of herbivory and nutrients on plant biomass and carbon storage in Vertisols of an East African savanna

Ngatia, Lucy W.; Turner, Benjamín L.; Njoka, Jesee Theuri; Young, Truman P.; Reddy, K. R.

doi:10.1016/j.agee.2015.04.025

Cited by 11 publications

(10 citation statements)

References 55 publications

(83 reference statements)

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“…Research has also demonstrated that grazing, one of the prominent forms of land use in the pastoral areas, affects plant growth (Li et al, 2015) and further impacts soil resource availability and plant nutrient status (Wang et al, 2014). Changes in the biogeochemical cycles of grassland ecosystems may have significant implications for plant nutrient resorption (Lü et al, 2013;Ngatia et al, 2015). However, there is a paucity of information on how grazing impacts nutrient resorption in plants and this study sought to fill this knowledge gap.…”

Section: Introductionmentioning

confidence: 99%

“…Firstly, leaf nutrient resorption is impacted by livestock grazing (Millett et al, 2005) depending on the plant's growth stage (Yasumura et al, 2005), thereby changing the plant community structure and productivity, soil microbial communities, as well as the physical and chemical properties of the soil (Li et al, 2008;He et al, 2011). However, the outcome and magnitude of the grazing effect on plant nutrient resorption processes remain unclear (Ngatia et al, 2015). Secondly, the preference of livestock for different forage species, trampling of the soil, and the return of excreta to the soil alters plant N and P concentrations (Heyburn et al, 2017), which invariably influence plant nutrient resorption.…”

Section: Introductionmentioning

confidence: 99%

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Different responses of plant N and P resorption to overgrazing in three dominant species in a typical steppe of Inner Mongolia, China

Wang

Jimoh

et al. 2020

PeerJ

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Nutrient resorption from senesced leaves is an important mechanism for nutrient conservation in plants. However, little is known about the effect of grazing on plant nutrient resorption from senesced leaves, especially in semiarid ecosystems. Here, we evaluated the effects of grazing on N and P resorption in the three most dominant grass species in a typical steppe in northern China. We identified the key pathways of grazing-induced effects on N and P resorption efficiency. Grazing increased N and P concentrations in the green leaves of Leymus chinensis and Stipa grandis but not in Cleistogenes squarossa. Both L. chinensis and S. grandis exhibited an increasing trend of leaf N resorption, whereas C. squarrosa recorded a decline in both leaf N and P resorption efficiency under grazing. Structural equation models showed that grazing is the primary driver of the changes in N resorption efficiency of the three dominant grass species. For L. chinensis, the P concentration in green and senesced leaves increased the P resorption efficiency, whereas the senesced leaf P concentration played an important role in the P resorption efficiency of C. squarrosa. Grazing directly drove the change in P resorption efficiency of S. grandis. Our results suggest that large variations in nutrient resorption patterns among plant species depend on leaf nutritional status and nutrient-use strategies under overgrazing, and indicate that overgrazing may have indirect effects on plant-mediated nutrient cycling via inducing shifts in the dominance of the three plant species.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Different responses of plant N and P resorption to overgrazing in three dominant species in a typical steppe of Inner Mongolia, China

Wang

Jimoh

et al. 2020

PeerJ

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

“…Overgrazing potentially alters plant nutrient resorption through different mechanisms (Lü et al 2015;Millett and Edmondson 2015;Ngatia et al 2015). Firstly, leaf nutrient resorption is impacted by livestock grazing (Millett et al, 2005) depending on the plant's growth stage (Yasumura et al 2005), thereby changing the plant community structure and productivity, soil microbial communities, as well as the physical and chemical properties of the soil (Li et al 2008;He et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Peer Review #2 of "Different responses of plant N and P resorption to overgrazing in three dominant species in a typical steppe of Inner Mongolia, China (v0.1)"

2020

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Nutrient resorption from senesced leaves is an important mechanism for nutrient conservation in plants. However, little is known about the effect of grazing on plant nutrient resorption from senesced leaves, especially in semiarid ecosystems. Here, we evaluated the effects of grazing on N and P resorption in the three most dominant grass species in a typical steppe in northern China. We identified the key pathways of grazinginduced effects on N and P resorption efficiency. Grazing increased N and P concentrations in the green leaves of Leymus chinensis and Stipa grandis but not in Cleistogenes squarossa. Both L. chinensis and S. grandis exhibited an increasing trend of leaf N resorption, whereas C. squarrosa recorded a decline in both leaf N and P resorption efficiency under grazing. Structural equation models showed that grazing is the primary driver of the changes in N resorption efficiency of the three dominant grass species. For L. chinensis, the P concentration in green and senesced leaves increased the P resorption efficiency, whereas the senesced leaf P concentration played an important role in the P resorption efficiency of C. squarrosa. Grazing directly drove the change in P resorption efficiency of S. grandis. Our results suggest that large variations in nutrient resorption patterns among plant species depend on leaf nutritional status and nutrient-use strategies under overgrazing, and indicate that overgrazing may have indirect effects on plantmediated nutrient cycling via inducing shifts in the dominance of the three plant species.

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“…Patchiness in nutrient availability can be governed by variability in soil properties or terrain, spatial variability in microbial community composition, or differential nutrient affinities across functional groups that have different spatial or temporal distributions (Reich et al, 2003; Ratnam et al, 2008). Perhaps as a result of this spatial heterogeneity, N, P, and N + P limitations on vegetation productivity have all been documented in African savanna or grassland systems (Augustine, McNaughton & Frank, 2003; Craine, Morrow & Stock, 2008; Okin et al, 2008; Ngatia et al, 2015). This study asks whether new approaches that actively test (sensu McIntire & Fajardo, 2009) the scale of grass response to nutrients and herbivory can aid understanding of nutrient limitation in grassland ecosystems.…”

Section: Introductionmentioning

confidence: 99%

Grassland productivity in response to nutrient additions and herbivory is scale-dependent

Smithwick

Baldwin

Naithani

2016

PeerJ

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Vegetation response to nutrient addition can vary across space, yet studies that explicitly incorporate spatial pattern into experimental approaches are rare. To explore whether there are unique spatial scales (grains) at which grass response to nutrients and herbivory is best expressed, we imposed a large (∼3.75 ha) experiment in a South African coastal grassland ecosystem. In two of six 60 × 60 m grassland plots, we imposed a scaled sampling design in which fertilizer was added in replicated sub-plots (1 × 1 m, 2 × 2 m, and 4 × 4 m). The remaining plots either received no additions or were fertilized evenly across the entire area. Three of the six plots were fenced to exclude herbivory. We calculated empirical semivariograms for all plots one year following nutrient additions to determine whether the scale of grass response (biomass and nutrient concentrations) corresponded to the scale of the sub-plot additions and compared these results to reference plots (unfertilized or unscaled) and to plots with and without herbivory. We compared empirical semivariogram parameters to parameters from semivariograms derived from a set of simulated landscapes (neutral models). Empirical semivariograms showed spatial structure in plots that received multi-scaled nutrient additions, particularly at the 2 × 2 m grain. The level of biomass response was predicted by foliar P concentration and, to a lesser extent, N, with the treatment effect of herbivory having a minimal influence. Neutral models confirmed the length scale of the biomass response and indicated few differences due to herbivory. Overall, we conclude that interpretation of nutrient limitation in grasslands is dependent on the grain used to measure grass response and that herbivory had a secondary effect.

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The effects of herbivory and nutrients on plant biomass and carbon storage in Vertisols of an East African savanna

Cited by 11 publications

References 55 publications

Different responses of plant N and P resorption to overgrazing in three dominant species in a typical steppe of Inner Mongolia, China

Different responses of plant N and P resorption to overgrazing in three dominant species in a typical steppe of Inner Mongolia, China

Peer Review #2 of "Different responses of plant N and P resorption to overgrazing in three dominant species in a typical steppe of Inner Mongolia, China (v0.1)"

Grassland productivity in response to nutrient additions and herbivory is scale-dependent

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