Effects of Plant Secondary Compounds on Nutritional Carrying Capacity Estimates of a Browsing Ungulate

Windels, Steve K.; Hewitt, David G.

doi:10.2111/rem-d-10-00078.1

Cited by 12 publications

(14 citation statements)

References 52 publications

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“…Seasonal changes in plant secondary metabolites such as tannins reduce digestible N of woody browse for moose and white‐tailed deer ( Odocoileus virginianus ) that likewise impair protein gains (McArt et al. , Windels and Hewitt ). Although caribou and reindeer can tolerate fiber and some plant secondary metabolites, the dynamic nature of these anti‐nutrients probably contributes to variability in forage selection among populations.…”

Section: Discussionmentioning

confidence: 99%

The nitrogen window for arctic herbivores: plant phenology and protein gain of migratory caribou (Rangifer tarandus)

et al. 2018

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Abstract. Terrestrial plants are often limited by nitrogen (N) in arctic systems, but constraints of N supply on herbivores are typically considered secondary to those of energy. We tested the hypothesis that forage N is more limiting than energy for arctic caribou by collecting key forages (three species of graminoids, three species of woody browse, and one genus of forb) over three summers in the migratory range of the Central Arctic Herd in Alaska from the Brooks Range to the Coastal Plain on the Arctic Ocean. We combined in vitro digestion and detergent extraction to measure fiber, digestible energy, and usable fractions of N in forages (n = 771). Digestible energy content fell below the minimum threshold value of 9 kJ/g for one single forage group: graminoids, and only beyond 64-75 d from parturition (6 June), whereas all forages fell below the minimum threshold value for digestible N (1% of dry matter) before female caribou would have weaned their calves at 100 d from parturition. The window for digestible N was shortest for browse, which fell below 1% at 30-41 d from parturition, whereas digestible N contents of graminoids were adequate until 46-57 d from parturition. The low quality of browse as a source of N was also apparent from concentrations of available N (i.e., the N not bound to fiber) that were <1% at 72-80 d from parturition. The Coastal Plain may be favored by female caribou because available and digestible concentrations of N are not only greater than those on the Brooks Range, the window of usable N on the Coastal Plain extends the period of protein gain for females and their calves by 17 d. Conversely, inland areas with greater biomass and densities of digestible N than the Coastal Plain may be more favorable for large male caribou that begin gaining protein from spring to breed in autumn. Our study provides evidence that phenological windows for protein gain in caribou are both spatially and temporally dynamic and likely to affect the distribution and growth of the population.

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Section: Discussionmentioning

confidence: 99%

The nitrogen window for arctic herbivores: plant phenology and protein gain of migratory caribou (Rangifer tarandus)

et al. 2018

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“…These approaches clearly demonstrated that tannins can have variable, but often large, negative effects on protein digestibility. In addition, Windels and Hewitt (2011) showed that the negative effects of tannins on digestible protein and energy may reduce the carrying capacity of habitats for white‐tailed deer Odocoileus virginianus eating high‐tannin diets.…”

Section: Step 2 Knowing What Aspects Of Chemistry To Measure and Howmentioning

confidence: 99%

Translating nutritional ecology from the laboratory to the field: milestones in linking plant chemistry to population regulation in mammalian browsers

DeGabriel

Moore

Felton

et al. 2013

Oikos

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A central goal of nutritional ecology is to understand how variation in food quality limits the persistence of wild animal populations. Habitat suitability for browsing mammals is strongly aff ected by concentrations of nutrients and plant secondary metabolites (PSMs), but our understanding of this is based mostly on short-term experiments of diet selection involving captive animals. In the wild, browsers forage in biologically, chemically and spatially-complex environments, and foraging decisions in response to varying food quality will be correspondingly complicated. We have identifi ed four steps that must be achieved in order to translate our understanding from laboratory experiments to populations of mammalian browsers: 1) knowing what foods and how much of these wild browsers eat, as well as what they avoid eating; 2) knowing the relevant aspects of plant nutritional and defensive chemistry to measure in a given system and how to measure them; 3) understanding the spatial distribution of nutrients and PSMs in plant communities, the costs they impose on foraging and the eff ects on animals ' distributions; and 4) having appropriate statistical tools to analyse the data. We discuss prospects for each of these prerequisites for extending laboratory studies of nutritional quality, and review recent developments that may off er solutions for fi eld studies. We also provide a synthesis of how to use this nutritional knowledge to link food quality to population regulation in wild mammals and describe examples that have successfully achieved this aim.

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“…Therefore, application of NCC requires close consideration of the ecology of the organism and its environment. For ungulates, NCC depends on the species' foraging behavior relative to the ecology of plant species being consumed (Jefferies et al 1994;Hobbs et al 2003;Windels and Hewitt 2011). Within temperate and arctic ecozones, decreases in nutritional quality and availability of browse in winter increase the necessary digestion and foraging time relative to other seasons (Schwartz and Renecker 1997), and thus historically winter was considered the limiting period for temperate ungulates.…”

Section: Introductionmentioning

confidence: 99%

“…Early models often assumed complete forage availability, equal selection probability, or complete forage consumption (Mautz 1978a). However, later models recognized direct (e.g., snow burial, secondary chemicals) or indirect (e.g., predation risk) constraints on forage availability (Beck et al 2006;Windels and Hewitt 2011) and the complexity of diet selection (Renecker and Schwartz 1997), including browsing tolerance of forage (Van Gils et al 2004). The implications of these different structures are often unclear and complicate the application of NCC estimates as tools to guide management.…”

Section: Introductionmentioning

confidence: 99%

“…Methods for calculating forage available to ungulates vary, but initial ''forage supply-animal demand'' structures were very simple, assuming equal selection probability of all available forage species (Mautz 1978a). Ungulates, however, preferentially select certain forages over others because of their higher nutritional quality (e.g., crude protein, gross energy) and lower amounts of secondary chemicals (e.g., tannins), and to ensure the proper nutrient ratios (i.e., ''gut mixing'') in their diet (Bryant et al 1992;Windels and Hewitt 2011). Thus, these simple models likely overestimate the forage available and NCC estimates.…”

Section: Introductionmentioning

confidence: 99%

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Contrasting Winter Moose Nutritional Carrying Capacity Models on a Dynamic Landscape

Smythe

Sanchez

Epps

2019

Journal of Fish and Wildlife Management

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Many models used to estimate nutritional carrying capacity (NCC) for ungulates differ structurally, but the implications of those differences are frequently unclear. We present a comparative analysis of NCC estimates for a large herbivore in a dynamic landscape, using models that differ in structure and scope. We compared three model structures across three estimates of winter ranges under three winter-severity scenarios for an isolated, introduced moose Alces alces population on the Copper River Delta of south-central Alaska. Model estimates of NCC ranged from 205 to 4,592 moose, demonstrating the critical influences of model structure and assumptions when applying NCC. Furthermore, population estimates during recent severe winters suggest that past models underestimated NCC on the Copper River Delta. We conducted a sensitivity analysis of a preferred model and determined that model components with the highest and lowest sensitivity were snow depth and lignin- and tannin-caused reductions in forage nutritional quality, respectively. Our low sensitivity values for lignin and tannin influences on NCC contrast with results in other NCC estimates. Overall, our results reinforce the need for, and will hopefully assist, adaptive management in response to landscape, population, behavioral, and climatic changes on the Copper River Delta, and demonstrate the importance of understanding model assumptions and structure in application of NCC estimates in the management of large herbivores in variable ecosystems.

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Effects of Plant Secondary Compounds on Nutritional Carrying Capacity Estimates of a Browsing Ungulate

Abstract: Effects of plant secondary compounds on nutritional carrying capacity estimates of a browsing ungulate. Rangeland Ecology & Management, 64(3), 264-275.

Cited by 12 publications

References 52 publications

The nitrogen window for arctic herbivores: plant phenology and protein gain of migratory caribou (Rangifer tarandus)

The nitrogen window for arctic herbivores: plant phenology and protein gain of migratory caribou (Rangifer tarandus)

Translating nutritional ecology from the laboratory to the field: milestones in linking plant chemistry to population regulation in mammalian browsers

Contrasting Winter Moose Nutritional Carrying Capacity Models on a Dynamic Landscape

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