Ungulate vs. Landscape Control of Soil C and N Processes in Grasslands of Yellowstone National Park

Frank, Douglas A.; Groffman, Peter M.

doi:10.2307/176818

Cited by 168 publications

(267 citation statements)

References 54 publications

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“…Herbivores can change nitrogen input to the soil (Tracy and Frank 1998) and soil net nitrogen mineralisation (e.g. Holland et al 1992;Frank and Groffman 1998;Hamilton et al 1998), but the mineralisation rate is also strongly controlled by actual soil moisture (Holland et al 1992). Grazing can also affect the specific root uptake rate for nutrients (Ruess 1984).…”

Section: Discussionmentioning

confidence: 99%

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Which functional processes control the short-term effect of grazing on net primary production in grasslands?

et al. 2001

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Grazing has traditionally been viewed as detrimental to plant growth, but it has been proposed that under certain conditions, grazing may lead to compensatory or overcompensatory growth. However, comprehensive information on the relative role of the main functional processes controlling the response of net primary production (NPP) to grazing is still lacking. In this study, a modelling approach was used to quantify the relative importance of key functional processes in the response of annual canopy NPP to grazing for a West African humid grassland. The PEPSEE-grass model, which represents radiation absorption, NPP, water balance and carbon allocation, was used to compute total and aboveground NPP in response to grazing pressure. Representations of grazing and mineral nitrogen input to the canopy were simplified to focus on the vegetation processes implemented and their relative importance. Simulations were performed using a constant or resource-driven root/shoot allocation coefficient, and dependence or independence of conversion efficiency of absorbed light into dry matter on nitrogen availability. There were three main results. Firstly, the response of NPP to grazing intensity emerged as a complex result of both positive and negative, and direct and indirect effects of biomass removal on light absorption efficiency, soil water availability, grass nitrogen status and productivity, and root/shoot allocation pattern. Secondly, overcompensation was observed for aboveground NPP when assuming a nitrogen-dependent conversion efficiency and a resource-driven root/shoot allocation. Thirdly, the response of NPP to grazing was mainly controlled by the effect of plant nitrogen status on conversion efficiency and by the root/shoot allocation pattern, while the effects of improved water status and reduced light absorption were secondary.

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Section: Discussionmentioning

confidence: 99%

“…3. Accelerated or regulated nutrient recycling: plant growth may be stimulated by improved nutrient cycling induced by herbivory (Ruess 1984;Loreau 1995;McNaughton et al 1997;Frank and Groffman 1998;de Mazancourt et al 1999). 4.…”

Section: Introductionmentioning

confidence: 99%

Which functional processes control the short-term effect of grazing on net primary production in grasslands?

et al. 2001

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“…Several studies have demonstrated short term stimulations of denitrification rates following urine deposition (e.g. Monaghan and Barraclough 1993;de Klein and Logtestijn 1994;Fraser et al 1994; but see Frank and Groffman 1998b) and following defoliation events (Ruz-Jerez et al 1994;Luo et al 1999;). Increased denitrification rates at ecosystem-scale in response to long term (i.e.…”

Section: Introductionmentioning

confidence: 99%

Stimulation of soil nitrification and denitrification by grazing in grasslands: do changes in plant species composition matter?

Roux

Bardy

Loiseau³

et al. 2003

Oecologia

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Stimulation of nitrification and denitrification by long term (from years to decades) grazing has commonly been reported in different grassland ecosystems. However, grazing generally induces important changes in plant species composition, and whether changes in nitrification and denitrification are primarily due to changes in vegetation composition has never been tested. We compared soil nitrification- and denitrification-enzyme activities (NEA and DEA, respectively) between semi-natural grassland sites experiencing intensive (IG) and light (LG) grazing/mowing regimes for 13 years. Mean NEA and DEA (i.e. observed from random soil sampling) were higher in IG than LG sites. The NEA/DEA ratio was higher in IG than LG sites, indicating a higher stimulation of nitrification. Marked changes in plant species composition were observed in response to the grazing/mowing regime. In particular, the specific phytomass volume of Elymus repens was lower in IG than LG sites, whereas the specific volume of Lolium perenne was higher in IG than LG sites. In contrast, the specific volume of Holcus lanatus, Poa trivialis and Arrhenatherum elatius were not significantly different between treatments. Soils sampled beneath grass tussocks of the last three species exhibited higher DEA, NEA and NEA/DEA ratio in IG than LG sites. For a given grazing regime, plant species did not affect significantly soil DEA, NEA and NEA/DEA ratio. The modification of plant species composition is thus not the primary factor driving changes in nitrification and denitrification in semi-natural grassland ecosystems experiencing long term intensive grazing. Factors such as trampling, N returned in animal excreta, and/or modification of N uptake and C exudation by frequently defoliated plants could be responsible for the enhanced microbial activities.

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“…Many studies report the effects of insect outbreaks (Mattson and Addy 1975;Swank et al 1981), mega-herbivores (Pastor and Naiman 1992;Pastor et al 1993;Frank and Groffman 1998) or anthropogenic disturbances (Schowalter et al 1981), but it is less clear how endemic above-ground herbivory affects nutrient cycling and how it is related to below-ground soil chemistry. Seastedt et al (1983) found that low levels of consumption by canopy arthropods increased leaching of K + but not N from injured leaves.…”

Section: Introductionmentioning

confidence: 99%

Insect herbivores and the nutrient flow from the canopy to the soil in coniferous and deciduous forests

2001

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Phytophagous insects can have severe impacts on forested ecosystems in outbreak situations but their contribution to flows of energy and matter is otherwise not so well known. Identifying the role of phytophagous insects in forested ecosystems is partly hindered by the difficulty of combining results from population and community ecology with those from ecosystem ecology. In our study we compared the effects of aphids and leaf-feeding lepidopterous larvae on the epiphytic micro-organisms in the canopies of spruce, beech and oak, and on the vertical flow of energy and nutrients from the canopies down to the forest floor. We particularly searched for patterns resulting from endemic herbivory rather than outbreak situations. Excreta of lepidopterous larvae and aphids promoted the growth of epiphytic micro-organisms (bacteria, yeasts, filamentous fungi) on needles and leaves, which suggests that micro-organisms were energy limited. Leachates from needles and leaves of infested trees contained higher concentrations of dissolved organic C and lower concentrations of NH-N and NO-N, relative to uninfested trees. The seasonal abundance of herbivores and micro-organisms significantly affected the dynamics of throughfall chemistry; for instance, concentrations of inorganic N were lower underneath infested than uninfested trees during June and July. There was little difference between the chemistry of soil solutions collected from the forest floor beneath infested and uninfested trees. Thus, under moderate to low levels of infestation the effects of above-ground herbivory seems to be obscured in the soil through buffering biological processes.

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Ungulate vs. Landscape Control of Soil C and N Processes in Grasslands of Yellowstone National Park

Cited by 168 publications

References 54 publications

Which functional processes control the short-term effect of grazing on net primary production in grasslands?

Which functional processes control the short-term effect of grazing on net primary production in grasslands?

Stimulation of soil nitrification and denitrification by grazing in grasslands: do changes in plant species composition matter?

Insect herbivores and the nutrient flow from the canopy to the soil in coniferous and deciduous forests

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