Banca de DEFESA: FERNANDO IGNE ROCHA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : FERNANDO IGNE ROCHA
DATE: 17/12/2021
TIME: 13:30
LOCAL: videoconferência
TITLE:

Impact of forest-to-pasture conversion in the Western Amazonia on edaphic factors, microbiome, and animal health

KEY WORDS:

Amazonia. Pedodiversity. Soil biodiversity. Land-use change. Cattle health.

PAGES: 161
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

The pedosphere, a terrestrial layer of extreme dynamism between biotic and abiotic factors, expresses the fingerprints of the evolutionary relationship between humans x nature, and in the 20th century has seen an accelerated intensification of its use, culminating in the global alert about biodiversity "hotspots" and the imminent decline of these ecosystems. Not differently, the Amazonia is being largely submitted to such process, and the proximity to its tipping point - where the exhaustion of natural ecosystems will make the maintenance of its resources unsustainable - has already been alerted (AMIGO, 2020). With the advent of next-generation sequencing, the last decade marked significant advances in the recognition of microorganisms that are undetectable by classical microbiology tools. The use of such methods has made it possible to understand how forest-to-pasture conversion affects the composition, diversity, and function of edaphic microbiomes. However, little is yet known about the cascading-effect driven by such changes. The pioneering work of Dr. Jürgen Döbereiner reported that outbreaks of periodontitis in cattle (i.e., cara-inchada - CIb) are associated with transformations in the soil microbiota by opening or renewing pastures for extensive cattle grazing. However, available molecular methods have not made it possible to explore such observations. Here, regions with high importance for biodiversity conservation and immersed in a gradient of land-use change in Brazilian Western Amazonia were accessed. Forests and adjacent pastures on farms characterized as low and high severity level (LSL and HSL) of cattle periodontitis were selected. We characterized pedogenetically distinct soils, and through 16S rRNA gene sequencing, explored the microbiota associated with the forest floor (i.e., litter, root layer, and bulk soil), as well as pasture soil, forage, and subgingival biofilm from healthy and diseased cattle, with samples collected in August 2017. In general, the magnitude of transformation of soil variables is greater in those more weathered, however the sum of bases was consistently altered at all sites. We corroborate that, regardless of soil class, the microbial alpha diversity follows positive correlation with increasing soil pH, however, the joint evaluation of the forest floor layers evidenced that it harbors greater spatial heterogeneity (beta diversity) than the microbiota of pasture soils. The soil-plant-animal continuum study highlighted that LSL systems have a predominance of Bacilli and Gammaproteobacteria classes, higher copper contents in soils, and macro and micromineral contents in forage. HSL systems had higher abundance of Bacteroidia in forage and animals, and Actinobacteria in soils, and higher C:N ratio. The higher alpha and gamma diversity, and modularity in network analysis, indicate that the microbiota of HSL system is reflecting greater environmental stress, characterizing their dysbiosis. Finally, the study of water fluxes for the Boca do Acre/AM region pointed out that soils of pastures in the HSL system maintain degrees of saturation close to 90% in the rainy season, exposing forage and cattle to greater humidity events, with possible reduction of O2 for plant and microbial metabolism. The multidisciplinary approach used in this study allowed us to advance our understanding of the complexity associated with the cascade-effect of forest-to-pasture conversion and impacts on biodiversity and animal health.

BANKING MEMBERS:
Presidente - 084.646.497-70 - EDERSON DA CONCEIÇÃO JESUS - EMBRAPA
Interna - 1815763 - IRENE DA SILVA COELHO
Interno - 927.881.579-91 - JERRI ÉDSON ZILLI - EMBRAPA
Externa à Instituição - JOANA FALCAO SALLES
Externo à Instituição - LUC FELICIANUS MARIE ROUWS - EMBRAPA