Is there evidence of mesophication of oak forests in the Missouri Ozarks?
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In: Groninger, John W.; Holzmueller, Eric J.; Nielsen, Clayton K.; Dey, Daniel C., eds. Proceedings, 19th Central Hardwood Forest Conference; 2014 March 10-12; Carbondale, IL. General Technical Report NRS-P-142. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 139-153.
Many studies on oak-dominated forests of the Central Hardwood region (CHR) have reported increasing abundance of fire-sensitive species and poor recruitment of oak (Quercus spp.) in the absence of frequent fire. However, most of these studies were conducted in the eastern and central CHR, and the assumption that similar dynamics occur in the western CHR has not been fully substantiated. We investigated forest dynamics in relatively undisturbed, mature oak-hickory forests of the Missouri Ozarks during a 15-year period (1995-2010). Data for this study were from untreated sites (controls) of the Missouri Ozark Forest Ecosystem Project (MOFEP) that have not experienced wildfire or harvesting for over a half century. In order to evaluate the influence of site quality on compositional dynamics, we selected a subset of permanent plots found on four ecological land types (ELTs) spanning a range of site qualities. The density of maple (Acer spp.) seedlings (<1.5-inch diameter at breast height [d.b.h.]) increased on nearly all ELTs over the 15 year period. As of 2010, maples were the most abundant species in the seedling layer on higher quality ELTs, while oaks and hickories (Carya spp.) were a major component of the seedling layer of lower quality ELTs. However, oaks and hickories were a major component of the sapling (1.5- to 4.5-inch d.b.h.) layer of all ELTs, while maple was a minor component. In contrast to the understory dynamics, the oak-dominated overstories (≥4.5-inch d.b.h.) of all ELTs remained largely unchanged from 1995 to 2010. These findings supported four working hypotheses: (1) upland forests of the Missouri Ozarks are in early stages of mesophication where fire has been excluded for at least 50 years; (2) mesophication in the western CHR is occurring at a slower rate than in eastern portions of the CHR; (3) mesophication is slowest on xeric, south-facing slopes; and (4) the predominance of low quality soils and frequent drought in the Ozarks will limit these forests from reaching late stages of mesophication, particularly on xeric sites.
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Olson, Matthew G.; Stevenson, Aaron P.; Knapp, Benjamin O.; Kabrick, John M.; Jensen, Randy G. 2014. Is there evidence of mesophication of oak forests in the Missouri Ozarks?. In: Groninger, John W.; Holzmueller, Eric J.; Nielsen, Clayton K.; Dey, Daniel C., eds. Proceedings, 19th Central Hardwood Forest Conference; 2014 March 10-12; Carbondale, IL. General Technical Report NRS-P-142. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 139-153.