Summary
In North America over 82% of the formerly extensive tallgrass prairie ecosystem has been lost, primarily to agriculture. Attempts are being made at some localities to restore native prairie communities. This present study determined soil microbial responses during grassland restoration, and the effect of soil type and burning at the Konza Prairie Biological Station, Kansas (central USA).
Four study sites on similar soil types were selected: a conventionally tilled cropland (CTC) on former prairie soils; two restored grasslands (one in 1998 (RG98) and one in 1978 (RG78)) on former agricultural land; and an annually burned native tallgrass prairie (BNP).
Two further sites on a different soil type were also investigated: an unburned native tallgrass prairie (UNP) and a grassland restored in 2000 (RG00).
Soil samples were taken in summer and winter, and 16S rRNA gene libraries and phospholipid fatty acid (PLFA) analyses were undertaken to determine soil microbial responses overtime since grassland restoration.
Structure and composition of bacterial communities in the CTC soil were very different from the restored and native prairie. Soil physicochemical characteristics changed monotonically with age of restoration; soil organic carbon (g/kg) was around 18 for CTC soil, 17 in RG98, 28 in RG78 and 38 in the BNP. Time between sampling and establishment of grasslands was 0 years for CTC, 8 years for RG98, 28 years for RG78, and 75 years for BNP.
Microbial communities had a transitional bacterial community forming during restoration that differed from both cropland and native prairie. The microbial communities of RG98 and RG00 grasslands were also significantly different, even though only restored two years apart and managed similarly. This is attributable to differences in soil type and soil chemistry. Effects of burning and season (of soil collection) had little effect on microbial communities. Even after 28 years the microbial community was not fully restored.
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