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Soil Compaction and Arbuscular mycorrhizae Affect Seedling Growth of Three Grasse s

Soil compaction is a major limiting factor in restoring native vegetation on reclaimed surface mined land in the Appalachian coal mining region of the eastern USA. It limits available water and nutrients, reduces pore volume, restricts root elongation and development, reduces plant growth, and leads to anaerobic conditions that many plants are unable to tolerate.

Previously, non-native forage species such as tall fescue (Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.) have been planted because they easily established on reclaimed mine soil. And some studies have shown that establishing large-statured, robust prairie species as an alternative to low-diversity forage complexes might improve soil conditions on reclaimed mine land over time.

In this study, the authors conducted a 10-week glasshouse study comparing growth of “Pete” eastern gamagrass (Tripsacum dactyloides L.), “Bison” big bluestem (Andropogon gerardii Vitman), and “Jesup MaxQ” tall fescue at soil bulk densities (BD) of 1.0, 1.3, and 1.5 g·cm-3. They also examined effects of arbuscular-mycorrhizal fungi (AMF) on plant growth in relation to compaction. Sources of AMF were a reclaimed surface coal mine soil and a native tall grass prairie soil.

The results indicated that shoot and root biomass of tall fescue and big bluestem were reduced at 1.5 BD while eastern gamagrass growth was not affected. Growth of big bluestem and eastern gamagrass was greater with AMF than without, but similar between AMF sources. Tall fescue growth was not enhanced by AMF. Overall, tall fescue biomass was 3 times greater than eastern gamagrass and 6 times greater than big bluestem when comparing only AMF-colonized grasses. Eastern gamagrass and big bluestem were both slower to establish than tall fescue. Eastern gamagrass appeared to be more tolerant of compaction, while big bluestem appeared somewhat less tolerant.

In conclusion, the AMF associated with cool-season forage grasses on reclaimed mine soil in this study is suitable for establishment of warm-season AMF dependent prairie grasses like big bluestem and eastern gamagrass. And successful establishment of warm-season prairie grasses on compacted reclaimed mine soil will require effective AMF and considerably more time than cool season grasses such as tall fescue, but could useful in increasing biological diversity.

Article by Mark Thorne, et al, from The Ohio State University, Columbus, USA.

Full access: http://mrw.so/4py3FG

Image by Bill Harms, from Flickr-cc.

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