COS 53-7
Microbial community response to increased years of grassland restoration under the Conservation Reserve Program in semiarid sandy soils
The composition and diversity of soil microbial communities are often coupled to the assessment of soil processes to better address the ecosystem response to disturbances and recovery. We investigated changes in bacterial and fungal community composition and diversity with increasing time under grassland restoration (0-26 years) in semi-arid soils through the Conservation Reserve Program (CRP). We targeted Amarillo fine sandy loam soils which were enrolled into this program for being highly erodible and ecologically sensitive to land-use changes in the Southern High Plains region. Soil samples (0-10 cm) were collected in July 2012 from seven dryland crop fields that represented 0 years (control) under restoration, sixteen (CRP) grasslands that ranged from 6-26 years under restoration and three native rangelands that had been never plowed or cropped across seven counties in northwest Texas. Based on years of restoration, fields were grouped into 8 groups: 0, 6, 12, 14, 21, 23, 26 and native rangelands (NR, age unknown). The 454 pyrosequencing was used to determine bacterial (16S rRNA gene) and fungal (18S rRNA gene) community composition. Data analyses included distance-based redundancy analysis (dbRDA), indicator species analysis (ISA) and phylogenetic diversity according to the Shannon diversity index and species richness.
Results/Conclusions
Microbial richness and Shannon diversity of bacteria or fungi were not affected significantly by time under restoration. Bacterial community composition, using unweighted unifrac distances, was affected significantly by years of restoration (p<0.03) and distinct groups were identified by dbRDA. ISA identified unique genera for all age groups except NR (p<0.05). Eight were identified for group 6 (Serinibacter, Lentisphaera, Craurococcus, Zoogloea, Aeromicrobium, Halomonas, Micrococcus, Pseudomonas), seven for 21 (Escherichia, Georgenia, Sinobacter, Rubrivivax, Hyalangium, Aquaspirillum, Thermomonas), three for 12 (Fibrella, Prosthecobacter, Verrucomicrobium) and 23 (Couchioplanes, Acrocarpospora, Pedomicrobium) and one for 14 (Prosthecomicrobium) and 26 (Chitinophaga). Fungal community composition (genus level) was not affected by years under restoration (p<0.28), however, ISA identified specific taxa according to age (p<0.05) in group 0 (Acremonium), 6 (Septoria, Coniosporium), 12 (Parasola, Thanatephorus), 26 (Paecilomyces, Devriesia, Staninwardia (p<0.001)), and NR (Phaeococcomyces, Colletotrichum, Dendroclathra). Additionally, certain trends were present at the phylum level. For example, between 0 and 26 years of restoration, the relative abundance of Ascomycetes increased 25% and the relative abundance of Glomeromycetes and Basidiomycetes decreased 78 and 24%, respectively. Severe drought during 2010-2012 may have influenced these results and curtailed the effect of restoration time. A second sampling is planned in 2014 under improved conditions.