Nutrient dynamics of reindeer forage species along snowmelt gradients at different ecological scales

Mårell, Anders; Hofgaard, Annika; Danell, Kjell

doi:10.1016/j.baae.2005.04.005

Cited by 75 publications

(65 citation statements)

References 41 publications

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“…We expected spatial heterogeneity in growing season temperature along an elevation gradient to influence the crude protein content of alpine sweetvetch roots. This is because high elevation sites experience later spring greenup and earlier fall frosts than low elevation sites, which results 8 ISRN Ecology in regional differences in plant phenology and gradients of forage quality [50]. Unlike Hamer and Herrero [29], a slope/aspect relationship based on our measures of solar radiation was not supported.…”

Section: Discussioncontrasting

confidence: 41%

Spatial and Temporal Heterogeneity Creates a “Brown Tide” in Root Phenology and Nutrition

2012

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Spatial and temporal heterogeneity in plant phenology and nutrition benefits herbivores by prolonging the period in which they can forage on nutritious plants. Landscape heterogeneity can therefore enhance population performance of herbivores and may be a critically important feature of their habitat. The benefits of resource heterogeneity over space and time should extend not only to large herbivores using above-ground vegetation but also to omnivores that utilize below-ground resources. We used generalized linear models to evaluate whether spatial heterogeneity influenced temporal variation in the crude protein content of alpine sweetvetch (Hedysarum alpinum) roots in west-central Alberta, Canada, thereby potentially offering nutritional benefits to grizzly bears (Ursus arctos). We demonstrated that temporal patterns in the crude protein content of alpine sweetvetch roots were influenced by spatial heterogeneity in annual growing season temperatures and soil moisture and nutrients. Spatial heterogeneity and asynchrony in the protein content of alpine sweetvetch roots likely benefit grizzly bears by prolonging the period they can forage on high quality resources. Therefore, we have presented evidence of what we termed a "brown wave" or "brown tide" in the phenology and nutrition of a below-ground plant resource, which is analogous to the previously described "green wave" in above-ground resources.

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Section: Discussioncontrasting

confidence: 41%

Spatial and Temporal Heterogeneity Creates a “Brown Tide” in Root Phenology and Nutrition

2012

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“…The method provides reasonable estimates for the time of green-up; the green-up dates determined with this method are only 10-20 days after snowmelt. This estimate more or less agrees with the time of major leaf expansion (Marell et al 2006;Pornon and Lamaze 2007). White et al (2009) compared 10 methods for detecting green-up from RS and also found that method a (Midpoint pixel of White et al (2009)) was one of the only two that was well correlated to start of spring (SOS) measures and with a low bias.…”

Section: Discussionmentioning

confidence: 54%

Predicting the time of green up in temperate and boreal biomes

Kaduk

Los

2010

Climatic Change

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The referenced publication included a methodological error that affects a portion of the reported results for registered Democrats by about 1 percentage point on average.The original publication provides estimates of the distribution of public opinion among Republicans and Democrats. The estimates were constructed by combining survey data with US voter file data, census American Community Survey (ACS) data, and other data in a multilevel regression model. The voter file data are cross-tabulated counts of containing the number of American adults in different partisan and demographic subgroups and for each unique geographic area (i.e., states and congressional districts).Estimates for registered Democrats were in error because we mislabeled a subset of Democratic district-level voter file crosstabs at an early stage in the data preparation process. As a result, the subpopulation numbers for the Democratic opinion estimates were based on the number of Republicans in each demographic-geographic subtype Climatic Change (2018) 147:355-358 https://doi

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“…We suggest that this effect is mediated by the ability of herbivores to exploit spatial heterogeneity in forage quality. Differences in plant phenology resulting from variation in elevation in mountainous regions create gradients of forage quality (Albon and Langvatn 1992;Mårell et al 2006); ungulates in mountainous areas respond by moving along these gradients and in so doing, are able to extend the period when they can obtain forage of peak quality (Albon and Langvatn 1992;Frank and McNaughton 1992;Mysterud et al 2001), thereby enhancing their body condition (Albon and Langvatn 1992;Mysterud et al 2001). Ungulate populations that did not migrate and were free of large carnivore predation in New Forest, St. Kilda, and Rum Island showed strong density dependence of population growth (Table 1).…”

Section: Discussionmentioning

confidence: 99%

“…Landscapes with heterogeneous aspects and elevations create spatial heterogeneity in the timing of snowmelt and plant growth (Albon and Langvatn 1992), and spatial variation in forage nitrogen content and fibrousness is well explained by date of snow retreat (Mårell et al 2006). We calculated the standard deviation of elevation of areas within 25 km of the center of herbivore ranges.…”

Section: Methodsmentioning

confidence: 99%

Density dependence in northern ungulates: interactions with predation and resources

et al. 2008

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Variation in the abundance of animals has traditionally been explained as the outcome of endogenous forcing from density dependence and exogenous forcing arising from variation in weather and predation. Emerging evidence suggests that the effects of density dependence interact with external influences on population dynamics. In particular, spatial heterogeneity in resources and the presence of capable predators may weaken feedbacks from density dependence to growth of populations. We used the Kalman filter to analyze 23 time series of estimates of abundance of northern ungulate populations arrayed along a latitudinal gradient (latitude range of 40°-70°N) to evaluate the influence of spatial heterogeneity in resources and predation on density dependence. We also used contingency tables to test whether density dependence was independent of the presence of carnivores (our estimate of predation) and multiple regressions to determine the effects of spatial heterogeneity in resources, predation, and latitude on the strength of density dependence. Our results showed that the strength of density dependence of ungulate populations was low in the presence of large carnivores, particularly at northern latitudes with low primary productivity. We found that heterogeneity in elevation, which we assume acted as a surrogate for spatial heterogeneity in plant phenology, also reduced effects of density dependence. Thus, we show that external forces created by heterogeneity in resources and predation interact with internal feedbacks from population density to shape dynamics of populations of northern ungulates.

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Nutrient dynamics of reindeer forage species along snowmelt gradients at different ecological scales

Cited by 75 publications

References 41 publications

Spatial and Temporal Heterogeneity Creates a “Brown Tide” in Root Phenology and Nutrition

Spatial and Temporal Heterogeneity Creates a “Brown Tide” in Root Phenology and Nutrition

Predicting the time of green up in temperate and boreal biomes

Density dependence in northern ungulates: interactions with predation and resources

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