Urochloa decumbens Has Higher Mycorrhizal Colonization in Degraded than in Pristine Areas in the Brazilian Cerrado

Abstract

Brazil has extensive degraded areas, where vegetation fails to establish due to harsh soil conditions. However, some invasive species such as Urochloa decumbens are successful pioneers in such areas, but the reasons deserve investigation. Mycorrhizal fungi are abundant in Cerrado soils, and their association with plants are beneficial for their establishment in natural and degraded areas. This study investigated whether arbuscular mycorrhizal colonization of native and exotic plants in the Cerrado differs between pristine and degraded areas. We collected 135 plants from four functional groups in 68 areas and determined the percentage of mycorrhizal colonization. The invasive grass Urochloa decumbens had significantly higher colonization rates in degraded than in native areas, and higher colonization than the native species. These results are important for soil management since Urochloa decumbens is widely used in early soil restoration efforts, and for nature conservation concerning the management of invasive plants in restoration areas.

Urochloa in Tropical Agroecosystems

“…Nonetheless, because U. decumbens is highly colonized by AM, it has been used in initial stages of land restoration programs in disturbed areas, where other species do not grow well under harsh soil conditions (Leite et al, 2019). Also, Urochloa is highly responsive to the increased availability of nutrients after fires (Pereira-Silva et al, 2019).…”

“…It has been found that in nutrient-poor pastures, Urochloa depends more on mycorrhizal fungi than C3 plants, especially in the initial seedling stages and during regrowth after periods of drought (Hetrick et al, 1990;Veenendaal et al, 1992). The use of U. decumbens in pastures in the Brazilian Cerrado has revealed high colonization by AMF, at a greater degree than native plants (Leite et al, 2019), which would partially explain the capacity of this species to develop in low fertility soils.…”

Inoculum origin and soil legacy can shape plant–soil feedback outcomes for tropical grassland restoration

“…Urochloa eminii legacies and invaded inocula caused high levels of root mycorrhizal colonization for both species, in line with evidence that U. eminii is a very efficient AMF propagator, through effectively changing the soil microbiota; it is even used in laboratories for mycorrhizal spore propagation (Banuelos et al 2014). Recent evidence also suggests U. eminii has the ability to accumulate spores in Cerrado areas invaded with exotic grasses (Leite et al 2019). Therefore, any living soil in which U. eminii has grown should generate large amounts of mycorrhizal spores, ultimately affecting future colonizers of any soil patch.…”