Bothriochloa ischaemum is a non-native, perennial C4 grass that has been seeded throughout the US Great Plains for erosion control and increased forage production. B. ischaemum frequently invades beyond planted areas, dominating an ecosystem as a monoculture. The invasion into native prairies by B. ischaemum may be facilitated by positive plant feedbacks, where B. ischaemum changes soil biotic and abiotic properties to benefit itself, with negative impacts on native plant species. Soil biotic communities such as gram negative, gram positive, saprophytic and arbuscular fungi drive the biogeochemistry of ecosystems. Disruption of plant-microbial associations can reduce or alter soil microbial communities, thereby altering above-ground species diversity. Invasive plant species may alter microbial communities to facilitate itself, resulting in monocultures with limited ecological services. Our research, conducted in Oklahoma and Kansas, USA, assesses plant community composition and soil biotic and abiotic properties in sites invaded by B. ischaemum, and in adjacent non-invaded prairie sites. Plant species richness was quantified using the point-intercept method. We determined soil moisture, aggregate stability for replicate invaded (n=6) and native sites (n=6). Relative abundance of soil microbial community functional groups was determined using phospholipid and neutral lipid fatty acid analyses.
Results/Conclusions
Preliminary results indicate significantly lower plant species richness in B. ischaemum invaded sites compared to the native prairie at both OK and KS locations. Both OK and KS invaded sites were lower in soil moisture and lower in overall microbial abundance, compared to the native sites. Lower soil water availability has been previously reported to reduce microbial activity and abundance. Our results indicate B. ischaemum may facilitate reductions in water availability, with a concomitant reduction in soil microbial biomass. The effect of invasion on soil aggregate stability was inconsistent across the two sites, with significantly more macro-aggregates (>2mm) in OK soils, compared to micro-aggregates (<2 mm), and fewer macro-aggregates in KS soils following invasion. Aggregate stability can be influenced by root structure and production, AM fungal hyphal production, and soil chemistry, and these parameters are currently being assessed in these sites. Our preliminary results indicate that in both KS and OK sites, B. ischaemum invasion resulted in negative effects above- and belowground, possibly leading to losses in many ecosystem services such as wildlife habitat, pollinator abundance, and reductions in microbial communities, soil carbon storage, erosion control and alterations in nutrient cycling