Aboveground vertebrate and invertebrate herbivore impact on net N mineralization in subalpine grasslands

Risch, Anita C.; Schütz, Martin; Vandegehuchte, Martijn L.; Putten, Wim H. van der; Duyts, Henk; Raschein, Ursina; Gwiazdowicz, Dariusz J.; Busse, Matt D.; Page‐Dumroese, Deborah S.; Zimmermann, Stephan

doi:10.1890/15-0300.1

Cited by 42 publications

(55 citation statements)

References 48 publications

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“…The impacts of insect herbivores, in particular, often rival or exceed those of their vertebrate counterparts [5–7], and insects often regulate plant biomass [8,9], increase species diversity [10], determine the outcomes of competitive interactions [6,11,12], and enhance nutrient recycling rates [4,5,13]. Since these processes result from plant consumption by, and subsequent growth of, insect herbivores, it is important to understand the nutritional constraints on insect performance and their subsequent community-level impacts.…”

Section: Introductionmentioning

confidence: 99%

Prospective evidence for independent nitrogen and phosphorus limitation of grasshopper (Chorthippus curtipennis) growth in a tallgrass prairie

2017

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Insect herbivores play a pivotal role in regulating plant production and community composition, and their role in terrestrial ecosystems is partly determined by their feeding behavior and performance among plants of differing nutritional quality. Historically, nitrogen (N) has been considered the primary limiting nutrient of herbivorous insects, but N is only one of many potential nutrients important to insect performance. Of these nutrients, phosphorus (P) is perhaps the most important because somatic growth depends upon P-rich ribosomal RNA. Yet relatively few studies have assessed the strength of P-limitation for terrestrial insects and even fewer have simultaneously manipulated both N and P to assess the relative strengths of N- and P-limitation. Here, we tested for potential N and P limitation, as well as N:P co-limitation, on Chorthippis curtipennis (Orthoptera, Acrididae), an abundant member of arthropod communities of central US prairies. Our results demonstrate weak evidence for both N and P limitation of C. curtipennis growth rates in laboratory feeding assays. Importantly, P-limitation was just as strong as N-limitation, but we found no evidence for NP co-limitation in our study. Furthermore, nutrient limitation was not apparent in field studies, suggesting that insect growth rates may be predominately controlled by other factors, including temperature and predation. Our results suggest that P should be jointly considered, along with N, as a primary determinant of herbivore feeding behavior under both current and future climate conditions.

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Section: Introductionmentioning

confidence: 99%

Prospective evidence for independent nitrogen and phosphorus limitation of grasshopper (Chorthippus curtipennis) growth in a tallgrass prairie

2017

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“…However, once released from grazing pressure, they can outcompete the other species due to faster growth rates (Lind et al 2013). As, again, Risch et al (2015) showed no differences in root biomass among our treatments in the tall-grass vegetation, this suggests that soil nutrients are not as readily available for plant uptake in this vegetation type (tall grass). In the tall-grass vegetation, forbs and legumes were also able to increase SLA when all herbivores were excluded (None), but this increase came at the cost of producing fewer leaves and therefore did not correlate with a change in dominance.…”

Section: Changes In Life Form Dominancementioning

confidence: 57%

“…Grasses increased in dominance by increasing tiller density, which may provide a competitive advantage (see also Sbrissa et al 2001). However, since the soil sustaining the short-grass vegetation is fairly nutrient rich for the constrained area of the SNP (Schütz et al 2006), andRisch et al (2015) showed increased soil N mineralization rates with progressive herbivore exclusion, our findings suggest that the mechanism behind the increased grass dominance was likely associated with increased soil nutrient exploitation. This could happen by decreasing the investment in root growth when grazing pressure is lowered (Milchunas and Lauenroth 1989) or by benefiting from the nutrient pools contained within the soil of nutrient-rich environments (Tilman 1988, Goldberg andLanda 1991).…”

Section: Changes In Life Form Dominancementioning

confidence: 73%

“…Sedges showed no significant change in dominance with the progressive exclusion of herbivores as well as few changes in leaf traits. We do not have information on root production of grasses, but we do know that overall root biomass did not differ among our treatments (Risch et al 2015). The production of additional leaves/tillers demands the acquisition of nutrients from other sources than the leaves themselves.…”

Section: Changes In Life Form Dominancementioning

confidence: 94%

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Herbivores sculpt leaf traits differently in grasslands depending on life form and land‐use histories

Firn

Schütz

Nguyen

et al. 2017

Ecology

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Vertebrate and invertebrate herbivores alter plant communities directly by selectively consuming plant species; and indirectly by inducing morphological and physiological changes to plant traits that provide competitive or survivorship advantages to some life forms over others. Progressively excluding aboveground herbivore communities (ungulates, medium and small sized mammals, invertebrates) over five growing seasons, we explored how leaf morphology (specific leaf area or SLA) and nutrition (nitrogen, carbon, phosphorous, potassium, sodium, and calcium) of different plant life forms (forbs, legumes, grasses, sedges) correlated with their dominance. We experimented in two subalpine grassland types with different land-use histories: (1) heavily grazed, nutrient-rich, short-grass vegetation and (2) lightly grazed, lower nutrient tall-grass vegetation. We found differences in leaf traits between treatments where either all herbivores were excluded or all herbivores were present, showing the importance of considering the impacts of both vertebrates and invertebrates on the leaf traits of plant species. Life forms responses to the progressive exclusion of herbivores were captured by six possible combinations: (1) increased leaf size and resource use efficiency (leaf area/nutrients) where lower nutrient levels are invested in leaf construction, but a reduction in the number of leaves, for example, forbs in both vegetation types, (2) increased leaf size and resource use efficiency, for example, legumes in short grass, (3) increased leaf size but a reduction in the number of leaves, for example, legumes in the tall grass, (4) increased number of leaves produced and increased resource use efficiency, for example, grasses in the short grass, (5) increased resource use efficiency of leaves only, for example, grasses and sedges in the tall grass, and (6) no response in terms of leaf construction or dominance, for example, sedges in the short grass. Although we found multiple possible responses by life forms to progressive exclusion of herbivores, we also found some important generalities. Changes in leaf traits of legumes and grasses correlated with their increasing dominance in the short-grass vegetation and plants were more efficient at constructing photosynthetic tissue when herbivores are present with few exceptions. These results demonstrate that vertebrate and invertebrate herbivores are essential to maintain plant species richness and resource-use efficiency.

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“…Risch et al . ) influence plant α‐ and β‐diversity levels in our study area, with the number of plant species ranging from <10 to over 50 per 1 m 2 .…”

Section: Methodsmentioning

confidence: 98%

How to predict plant functional types using imaging spectroscopy: linking vegetation community traits, plant functional types and spectral response

et al. 2016

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Summary The comparable and integrated nature of plant functional types and advances in high‐spectral‐resolution remote sensing techniques (i.e. imaging spectroscopy) make their combination highly interesting for spatially continuous and repeatable large‐scale ecosystem monitoring. Depending on physical environment and stress, plants invest in covarying biochemical and structural traits, influencing spectral characteristics of vegetation. These traits are assumed to bear a more direct causal relationship to plant functional types than to plant life/growth forms. However, the connection between a vegetation community's functional and spectral response remains to be established. We assessed the correlation structure between (i) biochemical and structural vegetation traits (biomass, dry matter content, nitrogen content, neutral detergent fibre content), (ii) plant life/growth forms and (iii) seven plant functional types of two categories (strategy types, indicator values) collected in heterogeneous alpine grassland. We then used airborne imaging spectroscopy data from the same area to model and predict plant life/growth forms and plant functional types at the vegetation community level using partial least squares regression and validated our models based on an independent data set. We found high correlations between many of the biochemical and structural vegetation traits, plant life/growth forms and plant functional types tested. Using airborne imaging spectroscopy data, we successfully modelled and predicted most plant life/growth forms (R2 max. = 0·56) and all plant functional types (R2 max. = 0·62). However, model performance for plant life/growth forms decreased substantially during external validation and overall model consistency was low (average change in R2 = 72%), while plant functional type models were much more consistent (average change in R2 = 20%). Based on our findings, we developed a conceptual framework using the theory and methodology of vegetation ecology and imaging spectroscopy to link the vegetation community's functional to its spectral signature. Our results encourage the use of plant functional types in imaging spectroscopy in order to aid the large‐scale monitoring of ecosystems, which is particularly important given the increased availability of airborne data and the prospective launches of spaceborne instruments in the near future.

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Aboveground vertebrate and invertebrate herbivore impact on net N mineralization in subalpine grasslands

Cited by 42 publications

References 48 publications

Prospective evidence for independent nitrogen and phosphorus limitation of grasshopper (Chorthippus curtipennis) growth in a tallgrass prairie

Prospective evidence for independent nitrogen and phosphorus limitation of grasshopper (Chorthippus curtipennis) growth in a tallgrass prairie

Herbivores sculpt leaf traits differently in grasslands depending on life form and land‐use histories

How to predict plant functional types using imaging spectroscopy: linking vegetation community traits, plant functional types and spectral response

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