Piccolo MC, Neill C, Melillo JM, Cerri CC, Steudler PA (1996) [sup.15]N natural abundance
in forest and pasture soils of the Brazilian Amazon Basin.
For natural abundance
[sup.13]C analyses of soil and plant materials, the analytical procedure described by Krull and Skjemstad (2003) was used.
[N.sup.15] natural abundance
in soil-plant systems.
Worryingly, this natural abundance
is now on a watch list of biodiversity hot spots.
Change in land use from [C.sub.3]-dominant vegetation to [C.sub.4]-dominant vegetation provides analytical tools to differentiate [C.sub.3]-derived C (native vegetation) from [C.sub.4]-derived C in the whole SOC and C fractions, since natural abundance
[sup.13]C isotopic signatures of the former ([delta][sup.13]C values, -30%o to -24%o) differ from those of the latter ([delta][sup.13]C values, 14%o to - 11%o) (Balesdent et al.
Polyolefins were only present as blends with starch; in spite of the natural abundance
of polyisoprenoids, natural rubber was not mentioned.
The aims of the study were to examine the impact of stock on soil [sup.15]N natural abundance
([[Delta].sup.15]N) within the context of former seabird breeding, and to relate the [sup.15]N enrichment of plant material to both stock activity and soil [sup.15]N enrichment.
The [[Delta].sup.18]O value is defined as a measure of the [sup.18]O content of a sample, but is reported not as a concentration, but rather as a normalized difference from the natural abundance
of [sup.18]O in seawater.
.--For each species, we summed catches for the two years of sampling that took place before the fragmentation treatment was applied.
In hopes of restoring the toads' natural abundance
, Johnson is directing a species survival effort -- the only such program that the American Association of Zoological Parks and Aquariums has undertaken for amphibians.