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1

Body mass-population density scaling at the local scale: does the energy equivalence rule hold for forest mammals?

100%
Hoste-Danylow A., Danylow J., Ulrich W.
Polish Journal of Ecology
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2013
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tom 61
|
nr 4
The energy equivalence rule assumes that the scaling of population density with body mass is inversely proportional to the scaling of individual metabolic rate. As a result, the total population energy use, calculated as the product of individual metabolic rate and population density, is independent of body mass. Here we evaluated the validity of this rule at the scale of a single community of mammals. Strong linear dependencies were found between log-transformed individual metabolic rate and log-transformed body mass as well as between body mass and density. The slopes of these relationships are close to the predicted |3/4| value and, in accordance with the energy equivalence rule, exhibit opposite values. The results however supported this rule only at the scale of the whole community. When small and large species were considered separately, population energy use increased with body mass. Analyzing these two groups separately strongly decreased the range of body mass considered. Body mass range seems to be a critical factor to find support for the energy equivalence rule at the scale of a single community.
2

Body size and the relative abundance of species

84%
Ulrich W.
Ecological Questions
|
2008
|
tom 10
Existing models of species abundance distributions (SADs) can be divided into those that are based on concepts of common limited niche space (niche apportionment models, neutral models) and those that invoke standard statistical distributions (e. g. log-series, lognormal). While the first type of models assumes that competitive interactions lead to observed SADs, the models of the second type appear to be mainly statistical descriptors of SADs without deeper biological meaning. None of the models explicitly includes species body size as a factor influencing species abundances. Further, with the exception of recent neutral models they are not embedded into basic ecological and evolutionary models to explain local diversity and ecosystem functioning. Here I present a new random walk model of species abundances that is based on two well known ecological distributions, the abundance - body weight distribution and the species - body weight distribution to define long-term upper abundance boundaries (carrying capacities). I show that a simple random walk of species abundances around the carrying capacities not only generates observed SADs but is also able to explain other patterns of community structure like core - satellite distributions, temporal patterns of species turnover, variance - mean ratios, and biomass distributions.
3

Age-related relationship between annual productivity and body size of trees: testing the metabolic theory

84%
Cheng D. L., Wang G.-X., Zhong Q.-L.
Polish Journal of Ecology
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2009
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tom 57
|
nr 3
441-449
Metabolic theory of ecology predicts a 3/4 power relationship between annual productivity PT and body size MT (i.e., P ∞ M3/4), which has important implications to estimates of carbon fluxes, ecosystem health, global carbon budgets, and a variety of other phenomena. To test this prediction, we examined a large dataset for Chinese forests. Such dataset covers six major forest biomes and a total of 17 forest types grown across a range of annual temperature (–6.6 to 25.2ºC), mean annual rainfall (27 to 2989 mm), elevation (10 to 4240 m a.s.l.), and stand age (3 to 350 yrs.). Reduced major axis (RMA) regression analyses were used to compare the PT versus MT scaling exponents and normalization constants (i.e., slopes and Y-intercepts of log-log linear relationships, respectively). Comparisons were made for ten different age-sequences (stand age ranges from 20 to 200 yrs). When stand age was less than 100 yrs, relationship of PT versus MT had similar scaling exponents (αRMA » 1.0), while the Y-intercepts decreased systematically. When stand age exceeded 140 yrs, scaling exponents decreased (αRMA <0.86). Both the aboveground annual productivity and aboveground body size per individual tree (PA and MA, respectively) showed the same behavior. We therefore conclude that the relationship of PT versus MT systematically declined with the stand age, and was inconsistent with the predictions of metabolic theory
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