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University of New Mexico (2017)

Precipitation Patterns and Fungal Community Succession in a Seasonally Dry Secondary Tropical Savanna

Lopez, Sara R.

Titre : Precipitation Patterns and Fungal Community Succession in a Seasonally Dry Secondary Tropical Savanna

Auteur : Lopez, Sara R.

Université de soutenance : University of New Mexico

Grade : Doctor of Philosophy (PhD) 2017

Résumé
Life in seasonally dry areas strongly depends on pulses of precipitation during certain portions of the year. This is particularly relevant for Tropical savannas on the Caribbean coast of Colombia that have been converted from Tropical Dry Forests and subjected to permanent agricultural and grazing practices that in turn induce changes in nutrient status in these systems. Several studies have presented evidence for a shift in C and N dynamics following forest conversion, including a decrease in total soil organic carbon and changes in nitrogen status, but the consequences of forest conversion on soil microbial processes are poorly understood. No studies have examined the composition, succession and responses of fungal communities in this region. My analysis of monthly and daily rainfall totals indicate that “Sabanas” can be classified as pulse driven ecosystems, because dry conditions predominate even in the wet season, when days with precipitation are followed by several days with no precipitation. This work showed that time after treatment and not treatment alone affected the species composition of the fungal community. The results from the analysis of the 71 core species revealed that while certain indicator species were present at specific time points, the general pattern was that of a highly resistant and resilient fungal community inhabiting highly perturbed soils in this savanna. Finally, the dynamics of the composition and abundance of this fungal community seems to derive from a combination of factors involving interactions between precipitation and the types of carbon sources available during the decomposition process.

Mots Clés : soil fungi, dry savannas, soil ecology

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Page publiée le 13 décembre 2017, mise à jour le 17 octobre 2019