Reconstructing the soil food web of a 100 million-year-old forest: The case of the mid-Cretaceous fossils in the amber of Charentes (SW France)     

Sina Adl  Vincent Girard  Gérard Breton  Ardhini Maharning  Vincent Perrichot  Romain Vullo 《Soil biology & biochemistry》2011,43(4):726-735

Over the past decade, the mid-Cretaceous amber deposits of Charentes (SW France) have been intensively studied. The fossils investigated were not only limited to arthropods preserved in amber, but also included microorganisms, plant debris and vertebrate remains. This plethora of analyses provided important data about the ecology of the overall system, including sources of litter input into the soil and of the above-ground ecology. More precisely, they showed that most of the microfossils were those of soil organisms or organisms that participated in the ecology of the forest soil. This new discovery provided the opportunity to study the ecology of the soil as preserved in the 100 million years old Charentes amber. Indeed, the trophic links of the fossil forest soil have been reconstructed on the basis of the fossil assemblage discovered in amber outcrops and overlayed on a model ecological forest soil food web. We relied on existing phylogenetic information to discuss the absence of certain taxonomic groups in the fossilized specimens. Our synthesis shows that although the organisms of this ancient forest of Charentes were different from those of modern soils, the soil food web was organized functionally the same as modern soils. It also demonstrated that trophic links of the soil community were already diverse, including various means of predation, parasitism and organic matter decomposition. The most obvious differences are the absence of evidence for symbiotic root nitrogen fixation and mycorrhizae.  相似文献   

Soil community changes during secondary succession to naturalized grasslands     

Ardhini R. Maharning  Aaron A.S. Mills  Sina M. Adl 《Applied soil ecology》2009,41(2):137-147

Succession to a naturalized grassland from former agricultural land and pastures is accompanied by changes in plant biodiversity and in the soil community. These changes are the result of a reduction or elimination of management, fertilizer applications and of grazing by large herbivores. We review soil biology studies on agricultural land that are in various successional stages towards naturalized grasslands, where interactions between plant species composition changes and the soil ecology affect each other. In many chronosequence studies, the soil microbial community tends to shift towards a less bacterial, and more fungal dominated food web energy channel following a reduction in fertilizer inputs and grazing intensity. Whereas changes in microarthropod communities are obscured, nematode trophic functional group (ecological guild) changes respond to both plant and soil community changes. There are opportunities to further study the feedback interactions between roots and soil organisms in grasslands. A better understanding of the molecular feedback mechanisms would be beneficial in long-term grassland management.  相似文献