soil C:N:P and allometric scaling
Dear All
We would like to inform you about two recent papers which may be of interest.
The first paper just appeared in Global
Change Biology (Wiley/Blackwell):
ABSTRACT
The factors regulating the structure of food webs are a central focus of
community and ecosystem ecology, as trophic interactions among species
have important impacts on nutrient storage and cycling in many ecosystems.
For soil invertebrates in grassland ecosystems in the Netherlands, the
site-specific slopes of the faunal biomass to organism body mass relationships
reflected basic biochemical and biogeochemical processes associated with
soil acidity and soil C : N : P stoichiometry. That
is, the higher the phosphorus availability in the soil, the higher, on
average, the slope of the faunal biomass size spectrum (i.e., the higher
the biomass of large-bodied invertebrates relative to the biomass of small
invertebrates). While other factors may also be involved, these results
are consistent with the growth rate hypothesis from biological stoichiometry
that relates phosphorus demands to ribosomal RNA and protein production.
Thus our data represent the first time that ecosystem phosphorus availability
has been associated with allometry in soil food webs (supporting information
available online). Our results have broad implications, as soil invertebrates
of different size have different effects on soil processes.
This article is available from the journal's homepage or from F1000:
Welcome to F1000 Biology
- the expert guide to the most important advances in biology
"Studies
of allometric or scaling relationships in biology and ecology hold the
promise of revealing general structuring forces; this interesting study
explores how resource availability modulates those relationships. Across
a range of soil conditions, where pH and phosphorus availability ranged
widely, scaling slopes (plots of organism mass vs. abundance or biomass
expressed in different ways) varied consistently. In general, richer soils
(C:P was the strongest predictor) had slopes indicating greater representation
of larger organisms. The natural conclusion, which should be tested further,
is that high P conditions enhance trophic transfer efficiency, liberating
higher trophic levels from "bottom up" control. This study very
nicely integrates this resource-centric viewpoint with macroecological
patterns to indicate some potentially general rules of community structure
and ecosystem functioning." |
The second paper, by C Mulder, HA Den Hollander,
JA Vonk, AG Rossberg, GAJM Jagers op Akkerhuis & GW Yeates, will appear
in Naturwissenschaften (Springer) next week.
ABSTRACT
The large range of body-mass values of soil
organisms provides a tool to assess the ecological organization of soil
communities. The goal of this paper is to identify graphical and quantitative
indicators of soil community composition and ecosystem functioning, and
to illustrate their application to real soil food webs. The relationships
between log-transformed mass and abundance of soil organisms in 20 Dutch
meadows and heathlands were investigated. Using principles of allometry,
maximal use can be made of ecological theory to build and explain food
webs. The aggregate contribution of small invertebrates such as nematodes
to the entire community is high under low soil phosphorus content and causes
shifts in the mass–abundance relationships and in the trophic structures.
We show for the first time that the average of the trophic link lengths
is a reliable predictor for assessing soil fertility responses. Ordered
trophic link pairs suggest a self-organizing structure of food webs according
to resource availability and can predict environmental shifts in ecologically
meaningful ways.
Revised proofs available upon request (please
remember that this paper will be published Open Access as well, just like
the previous one).
In that way, supplementary material contained
in the Springer online version (doi:10.1007/s00114-009-0539-4) will be
available to all users.
Many thanks, best regards
Christian Mulder
Disclaimer RIVM
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