Modification of Ecosystems by Ungulates

Hobbs, N. Thompson

doi:10.2307/3802368

Cited by 807 publications

(812 citation statements)

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“…Moreo�er, pasture quality is affected by reindeer grazing as well as e.g. climate, weather and soil properties (Georgiadis et al, 1989;Hobbs, 1996;Post & Klein, 1996;Lenart et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Approaches to estimate body condition from slaughter records in reindeer

Olofsson

Danell

Forslund

et al. 2008

Ran

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Long-term fluctuations in population densities of reindeer and caribou are common, where pasture is the limiting resource. Pasture quality affects the nutritional status and production of the animals. Therefore, continuous information about changes in the grazing resources is important when making management decisions. �he ob�ecti�e of �he ob�ecti�e of this study was to in�estigate different possibilities of using routine and additional slaughter records as body condition indicators, and thereby indicators of pasture resources in the summer ranges of reindeer husbandry. Records from 696 reindeer slaughtered in the winter 2002/2003 were included in the study. We de�eloped a model with carcass weight as body condition indicator and two different models combining fatness, conformation, carcass weight, and body size as body condition indicators. �he results showed age and sex dependent differences between the �ariables, and differentiation of animal age and sex impro�ed the precision of models. Ad�usting weight for body size also impro�ed weight as a body condition indicator in adults. Conformation and fatness had good resemblance to weight and body size ad�usted weight and should preferably be included, together with carcass weight and body size measures, when estimating body condition from carcasses. Our analysis showed that using non-in�asi�e slaughter records is a good and non-expensi�e method of estimating body condition in reindeer.

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Section: Introductionmentioning

confidence: 99%

Approaches to estimate body condition from slaughter records in reindeer

Olofsson

Danell

Forslund

et al. 2008

Ran

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“…Large herbivores such as mule deer (Odocoileus hemionus) have profound impacts on ecosystem structure and function (Hobbs 1996, Manier & Hobbs 2007Fornara & Du Toit 2008;Beschta & Ripple 2009;Goheen et al 2010;Allred et al 2011;Gass & Binkley 2011;Nkwabi et al 2011;Bai et al 2012), and understanding the ways in which their behaviour, individual performance and population dynamics are likely to change under future climate scenarios is crucial for effective management of ecosystems. The condition of ungulates in winter is an important determinant of future fitness because of its impact on individual body condition at the start of the breeding season (Forchhammer et al 2001;Steinheim et al 2002;Solberg et al 2007;Rodriguez-Hidalgo et al 2010;Taillon et al 2012;Hurley et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Asynchronous vegetation phenology enhances winter body condition of a large mobile herbivore

et al. 2015

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Article (refereed) -postprintSearle, Kate R.; Rice, Mindy B.; Anderson, Charles R.; Bishop, Chad; Hobbs, N.T. 2015. Asynchronous vegetation phenology enhances winter body condition of a large mobile herbivore. Oecologia, 179 (2). 377-391. 10.1007/s00442-015-3348-9 Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. AbstractUnderstanding how spatial and temporal heterogeneity influence ecological processes forms a central challenge in ecology. Individual responses to heterogeneity shape population dynamics, therefore understanding these responses is central to sustainable population management. Emerging evidence has shown that herbivores track heterogeneity in nutritional quality of vegetation by responding to phenological differences in plants. We quantified the benefits mule deer (Odocoileus hemionus) accrue from accessing habitats with asynchronous plant phenology in northwest Colorado over three years. Our analysis examined both the direct physiological and indirect environmental effects of weather and vegetation phenology on mule deer winter body condition. We identified several important effects of annual weather patterns and topographical variables on vegetation phenology in the home ranges of mule deer. Crucially, temporal patterns of vegetation phenology were linked with differences in body condition, with deer tending to show poorer body condition in areas with less asynchronous vegetation green-up and later vegetation onset. The direct physiological effect of previous winter precipitation on mule deer body condition was much less important than the indirect effect mediated by vegetation phenology. Additionally, the influence of vegetation phenology on body fat was much stronger than that of overall vegetation productivity. In summary, changing annual weather patterns, particularly in relation to seasonal precipitation, have the potential to alter body condition of this important ungulate species during the critical winter period. This finding highlights the importance of maintaining large contiguous areas of spatially and temporally variable resources to allow animals to compensate behaviourally for changing climate-driven resource patterns.

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“…Ungulate browsing on natives may depress their abundance and ability to compete (21-24) and increase abiotic resources available to invaders (11,25,26), which can act synergistically to decrease communities' ability to resist invasion (biotic resistance; refs. 8 and 10).…”

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confidence: 99%

In a long-term experimental demography study, excluding ungulates reversed invader's explosive population growth rate and restored natives

Kalisz

Spigler

Horvitz

2014

Proc. Natl. Acad. Sci. U.S.A.

128

157

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A major goal in ecology is to understand mechanisms that increase invasion success of exotic species. A recent hypothesis implicates altered species interactions resulting from ungulate herbivore overabundance as a key cause of exotic plant domination. To test this hypothesis, we maintained an experimental demography deer exclusion study for 6 y in a forest where the native ungulate Odocoileus virginianus (white-tailed deer) is overabundant and Alliaria petiolata (garlic mustard) is aggressively invading. Because population growth is multiplicative across time, we introduce metrics that correctly integrate experimental effects across treatment years, the cumulative population growth rate, λ c , and its geometric mean, λ per-year , the time-averaged annual population growth rate. We determined λ c and λ per-year of the invader and of a common native, Trillium erectum. Our results conclusively demonstrate that deer are required for the success of Alliaria; its projected population trajectory shifted from explosive growth in the presence of deer (λ per-year = 1.33) to decline toward extinction where deer are excluded (λ per-year = 0.88). In contrast, Trillium's λ per-year was suppressed in the presence of deer relative to deer exclusion (λ per-year = 1.04 vs. 1.20, respectively). Retrospective sensitivity analyses revealed that the largest negative effect of deer exclusion on Alliaria came from rosette transitions, whereas the largest positive effect on Trillium came from reproductive transitions. Deer exclusion lowered Alliaria density while increasing Trillium density. Our results provide definitive experimental support that interactions with overabundant ungulates enhance demographic success of invaders and depress natives' success, with broad implications for biodiversity and ecosystem function worldwide.life table response experiment | herbivory | biotic resistance | temperate deciduous forest conservation | forest understory herbs S teadily increasing pressure by invasive plant species on native biodiversity (1) disrupts both community and ecosystem function (2) and results in staggering economic costs worldwide (3, 4). A major goal in ecology is to understand how changes over time in species interactions affect invasion success of exotic species (5-8). According to ecological theory, the ability of the resident community to limit the success of invading exotics [biotic resistance (9, 10)] will depend upon ecological context that includes the suite of local interactors (11-15). The abundance of herbivores and their local impacts (11,14,16) can play a prominent role in how fast plant populations grow or shrink and how much the relative abundance of plant species changes over time (5, 15), including changes associated with plant invasions (11,(16)(17)(18)(19). Recently, increased browsing pressure by overabundant ungulate herbivores on native plant communities has been proposed as a fundamental cause of a shift from native to exotic plant domination in forests and rangelands worldwide (11,16,20). Wild and domes...

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Modification of Ecosystems by Ungulates

Cited by 807 publications

References 120 publications

Approaches to estimate body condition from slaughter records in reindeer

Approaches to estimate body condition from slaughter records in reindeer

Asynchronous vegetation phenology enhances winter body condition of a large mobile herbivore

In a long-term experimental demography study, excluding ungulates reversed invader's explosive population growth rate and restored natives

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