Individual study: A comparison of survival and acorn production of swamp white oak Quercus bicolour seedlings reared by a containerized root production method vs. traditionally reared nursery stock, Smokey Waters and Plowboy Bend, Missouri, USA
Grossman B.C., Gold M.A. & Dey D.C. (2003) Restoration of hard mast species for wildlife in Missouri using precocious flowering oak in the Missouri River floodplain, USA. Agroforestry Systems, 59, 3-10
In parts of the Lower Missouri River floodplain of central-east USA, natural regeneration of oak Quercus species has been low following major floods. Increased planting of tree seedlings needs therefore to be considered. Traditional planting methods however, have limited success due for example to frequent flood events, and competition from faster growing vegetation. In this experiment, swamp white oak Quercus bicolour seedling survival and acorn production over three years after out-planting was compared between seedlings reared by a containerized root production method (RPMâ„¢) and traditionally reared nursery stock, with weed competition reduced by plastic weed mats.
Two 16.2 ha square (402 mÂ²) planting blocks were established at each of two conservation areas in the Missouri River floodplain managed by the Missouri Department of Conservation: Smokey Waters (Cole County) and Plowboy Bend (Moniteau County). One of each block pair was randomly assigned a cover crop treatment (redtop grass Agrostis alba), or no cover crop.
Seedlings planted (9.1 m x 9.1 m spacing; 120 trees/ha) were 18 to 24 month-old 1-0 bare root, and RPMâ„¢ seedlings (for a summary of the RPMâ„¢ rearing procedure please see: www.conservationevidence.com/ViewEntry.asp?ID=1300).
In randomly located 30-tree plots, RPMâ„¢ trees were planted in November 1999 and bare root seedlings in spring 2000. At the time of planting, a slow release fertilizer was applied around each seedling (approximate rate 30 g/tree); and a 1.2 x 1.2 m woven plastic weed mat was placed around each seedling in the spring to suppress weed growth.
Seedling measurements: Height and basal stem diameter were measured before the 2000 growing season, and again at the end of the first and second growing seasons (winters 2000/2001, 2001/2002). In August 2000, 2001 and 2002, any acorns produced were counted.
Seedling survival: Survival was initially high (around 95% for bare root and RPM™ oak seedlings). However, bare root seedling survival dropped to 77% by the end of year two, whilst RPM™ survival was above 95%.
Acorn production: Bare root stock produced no acorns over the 3-year monitoring period. In contrast, some RPM™ seedlings did produce acorns; for those that produced acorns during the first three years, average acorn production ranged from 4.3, 5.2 to 6.3 acorns/tree respectively. Some individual trees produced up to 45 acorns.
When compared with earlier directly planted acorns or traditional bare root plantings, and oaks originating from natural regeneration, RPM™ oak seedlings produced acorns10 to 15 years sooner, and were considered to be providing a valuable acorn food crop for wildlife.
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