Microbial communities in Cerrado soils under native vegetation subjected to prescribed fire and under pasture

Abstract

<jats:p>The objective of this work was to evaluate the effects of fire regimes and vegetation cover on the structure and dynamics of soil microbial communities, through phospholipid fatty acid (PLFA) analysis. Comparisons were made between native areas with different woody covers ("cerrado stricto sensu" and "campo sujo"), under different fire regimes, and a 20-year-old active palisadegrass pasture in the Central Plateau of Brazil. Microbial biomass was higher in the native plots than in the pasture, and the highest monthly values were observed during the rainy season in the native plots. No significant differences were observed between fire regimes or between communities from the two native vegetation types. However, the principal component (PC) analysis separated the microbial communities by vegetation cover (native x pasture) and season (wet x dry), accounting for 45.8% (PC1 and PC3) and 25.6% (PC2 and PC3), respectively, of the total PLFA variability. Changes in land cover and seasonal rainfall in Cerrado ecosystems have significant effects on the total density of soil microorganisms and on the abundance of microbial groups, especially Gram-negative and Gram-positive bacteria.</jats:p>

Diversity and Function of Bacterial Assemblages in Savanna Vegetation Soils

“…The beginning of the wet season is associated with an increase in microbial biomass (Nardoto and Bustamante 2003;da Silva 2004), microbial activity, organic carbon, and nitrification (da Silva 2004). These changes in soil water content appear to mask the effects of other factors, such as fire, on microbial communities (da Silva 2004;Viana et al 2011). In a study investigating the effects of the first rain events on dry Cerrado soil, denaturing gradient gel electrophoresis (DGGE) analysis and measurement of CO 2 and NO fluxes revealed that the bacterial community structure responds rapidly after artificial water addition (Pinto et al 2006).…”

“…This soil temperature is not lethal to microorganisms (Wells et al 1979); however, long-term effects of fire can include changes in vegetation cover and altered soil characteristics such as pH and nutrient availability. da Silva (2004) and Viana et al (2011) evaluated the effects of prescribed burning on soil microbial communities in two vegetation types of native Cerrado (woodland cerrado and shrubland). Although fire influenced soil moisture and pH, no significant differences were observed between microbial communities in the burned and unburned areas of either vegetation type.…”

“…Although fire influenced soil moisture and pH, no significant differences were observed between microbial communities in the burned and unburned areas of either vegetation type. The authors concluded that seasonal changes exert a greater influence than fire on soil microbial communities, as assessed by DGGE (da Silva 2004) and PLFA (Viana et al 2011) analyses, with an increase of microbial biomass carbon apparent soon after the first rains.…”

“…Although several papers did not describe these parameters, where reported these values were similar across the analyzed sites (protected or modified), indicating a predominance of clayey soils (Table 6.3). the median values of the included studies (Pinto et al 2006;Carvalho et al 2007;Quirino et al 2009;Bresolin et al 2010;Frazão et al 2010;Peixoto et al 2010;Viana et al 2011;Araujo et al 2012;Ganz et al 2012;Mendes et al 2012;Vinhal-Freitas et al 2013;Rachid et al 2013;Rampelotto et al 2013;Rossi et al 2013;Souza et al 2013 …”

“…Single linkage algorithm associated Euclidean similarity measure was used (correlation coefficient: 0.9667; bootstrap: 10,000) et al 2009) and modification of the microbial community structure (Pinto et al 2006;Roesch et al 2007;Bresolin et al 2010;Viana et al 2011;Rampelotto et al 2013;Souza et al 2013). Most of the studies (published from 2006 to 2013) assessed microbial biomass or used molecular fingerprinting techniques to understand these changes, but some studies characterized soil bacterial assemblies at the taxon level using high-throughput 16S rRNA gene sequencing.…”