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991.
Soil carbon saturation: concept,evidence and evaluation 总被引:20,自引:0,他引:20
Catherine E. Stewart Keith Paustian Richard T. Conant Alain F. Plante Johan Six 《Biogeochemistry》2007,86(1):19-31
Current estimates of soil C storage potential are based on models or factors that assume linearity between C input levels
and C stocks at steady-state, implying that SOC stocks could increase without limit as C input levels increase. However, some
soils show little or no increase in steady-state SOC stock with increasing C input levels suggesting that SOC can become saturated with respect to C input. We used long-term field experiment data to assess alternative hypotheses of soil carbon storage
by three simple models: a linear model (no saturation), a one-pool whole-soil C saturation model, and a two-pool mixed model
with C saturation of a single C pool, but not the whole soil. The one-pool C saturation model best fit the combined data from
14 sites, four individual sites were best-fit with the linear model, and no sites were best fit by the mixed model. These
results indicate that existing agricultural field experiments generally have too small a range in C input levels to show saturation
behavior, and verify the accepted linear relationship between soil C and C input used to model SOM dynamics. However, all
sites combined and the site with the widest range in C input levels were best fit with the C-saturation model. Nevertheless,
the same site produced distinct effective stabilization capacity curves rather than an absolute C saturation level. We conclude
that the saturation of soil C does occur and therefore the greatest efficiency in soil C sequestration will be in soils further
from C saturation.
相似文献
Catherine E. StewartEmail: |
992.
Renata Jurišić Grubešić Sanda Vladimir-Knežević Dario Kremer Zdenka Kalodera Jadranka Vuković 《Biologia》2007,62(2):148-156
Micromorphological investigation of the types, dimensions and distribution of characteristic trichomes in leaves and stems
in Teucrium L. species (T. arduini L., T. chamaedrys L., T. flavum L., T. montanum L., T. polium L., and T. scordium L. subsp. scordioides Schreb.) distributed in Croatia was carried out as part of the taxonomical study of the genus Teucrium. Secretory types of hairs, peltate and capitate hairs were observed on the epidermis of stems and leaves of all investigated
species. Non-secretory, acicular hairs were almost completely lacking on stems of T. scordium subsp. scordioides. Flagelliform hairs were not found in T. flavum and T. polium. Cladose hairs were present only in T. polium. The largest micromorphological variability was established between wild and cultivated samples of T. arduini and T. scordium subsp. scordioides, while cultivated and wild specimens of T. polium were almost identical. Differences were primarily observed in trichome dimensions and much less in micromorphological features. 相似文献
993.
Population dynamics of wireworms (Coleoptera,Elateridae) in arable land after abandonment 总被引:1,自引:0,他引:1
The community of elaterid larvae of three sites (field and two fallows), representing different stages of secondary succession,
were studied using soil sampling from 1986 to 1993. All three sites were abandoned arable land: a field cultivated until 1991,
a fallow I abandoned in 1986, and a fallow II abandoned about 1976. The fallow II was used as a meadow after abandonment and
was regularly mown until 1985, when cultivation stopped. Six species of Elateridae larvae were found at all three study sites.
In the field, Agriotes obscurus, Athous niger, Athous subsuscus, Dalopius marginatus and Athous vittatus were found, A. niger and A. obscurus being the most abundant species. During cultivation, larval densities were very low, however, larval abundance increased
up to 8.8 ± 8.3 ind. m-2 when cultivation stopped. Only small A. obscurus larvae were found during cultivation, whereas larval size increased after abandonment. In fallow I A. obscurus, A. niger, A. subsuscus, D. marginatus, and Agrypnus murinus were found and the average annual abundance fluctuated between 0.8 ± 1.4 to 40.8 ± 10.9 ind. m-2 with A. obscurus being the most abundant species. Fallow II supported the highest densities of wireworms from all plots studied (71.2±35.2
to 280.0±24.8 ind. m-2). A. obscurus, A. niger, A. subsuscus and D. marginatus were found in fallow II. The abundance of all larval Elateridae as well as the dominant species A. obscurus decreased during the study period, while simultaneously the occurrence of small sized A. obscurus larvae decreased. The frequency of cultivation and time elapsed since last cultivation appeared to be the most important
factors affecting elaterid occurrence in the field and fallow I. In fallow II, the decrease in abundance correlates with the
accumulation of a dense litter layer, which may correspond with soil surface structure, plant community changes or predator
pressure. 相似文献
994.
The influence of depth,site exposure and season on the intensity of iceberg scouring in nearshore Antarctic waters 总被引:2,自引:3,他引:2
Ice scour disturbance has a significant effect on the physical and biological characteristics of polar benthos. A series of
grids, each consisting of 25 markers, were deployed along depth transects and replicated at two contrasting study sites at
Adelaide Island, West Antarctic Peninsula. Markers were surveyed and replaced every 3 months for 2 years in order to assess
the frequency and intensity of iceberg impacts. Depth, site, season and year were all highly significant factors influencing
ice scouring frequency. We observed a high variation in the duration of winter fast ice between sites and years, which had
a marked effect on ice scouring frequency. The ecological effects of the disturbance regime are likely to include depth zonation
of benthic assemblages, patchiness of communities at varying stages of recovery and the near denudation of sessile fauna in
the shallow subtidal.
相似文献
Dan A. SmaleEmail: |
995.
996.
A new approach to rapid, genome-wide identification and ranking of horizontal transfer candidate proteins is presented. The method is quantitative, reproducible, and computationally undemanding. It can be combined with genomic signature and/or phylogenetic tree-building procedures to improve accuracy and efficiency. The method is also useful for retrospective assessments of horizontal transfer prediction reliability, recognizing orthologous sequences that may have been previously overlooked or unavailable. These features are demonstrated in bacterial, archaeal, and eukaryotic examples. 相似文献
997.
Power-law-like distributions in biomedical publications and research funding 总被引:1,自引:0,他引:1 下载免费PDF全文
Gene annotation, as measured by links to the biomedical literature and funded grants, is governed by a power law, indicating that researchers favor the extensive study of relatively few genes. This emphasizes the need for data-driven science to accomplish genome-wide gene annotation. 相似文献
998.
Background
Affymetrix GeneChip technology enables the parallel observations of tens of thousands of genes. It is important that the probe set annotations are reliable so that biological inferences can be made about genes which undergo differential expression. Probe sets representing the same gene might be expected to show similar fold changes/z-scores, however this is in fact not the case. 相似文献999.
Max Bylesjö Daniel Eriksson Andreas Sjödin Stefan Jansson Thomas Moritz Johan Trygg 《BMC bioinformatics》2007,8(1):207
Background
During generation of microarray data, various forms of systematic biases are frequently introduced which limits accuracy and precision of the results. In order to properly estimate biological effects, these biases must be identified and discarded. 相似文献1000.
Rui P Galao Nicoletta Scheller Isabel Alves-Rodrigues Tanja Breinig Andreas Meyerhans Juana Díez 《Microbial cell factories》2007,6(1):32
The yeast Saccharomyces cerevisiae is a well-established model system for understanding fundamental cellular processes relevant to higher eukaryotic organisms.
Less known is its value for virus research, an area in which Saccharomyces cerevisiae has proven to be very fruitful as well. The present review will discuss the main achievements of yeast-based studies in basic
and applied virus research. These include the analysis of the function of individual proteins from important pathogenic viruses,
the elucidation of key processes in viral replication through the development of systems that allow the replication of higher
eukayotic viruses in yeast, and the use of yeast in antiviral drug development and vaccine production. 相似文献