RESPONSE OF EIGHT CULTIVARS OF ACER × FREEMANII AND ACER RUBRUM TO SOIL COMPACTION

Compaction is often indicated as a widespread problem in urban and suburban landscapes. Construction activities, foot and vehicular traffic and limited mulching all may contribute to compaction. The objectives of this study were to assess the effects of compaction on tree establishment and growth and to characterize soil factors that contribute to lack of vigor. Red and Freeman maple (Acer rubrum and Acer × freemanii) cultivars were chosen for the study because they are commonly planted for their attractive fall color and overall versatility. Freeman maple is a naturally occurring hybrid of red and silver maples, and is often touted as being more tolerant of difficult urban sites than either parent. We compacted field plots to bulk densities considered restrictive to tree growth and left the control plots at the pre-existing bulk densities. Along with measuring tree growth factors, we also measured various soil attributes. Genetics is the primary factor controlling plant response to compaction for all biomass measures. Generally, all cultivars growing in the un-compacted plots had a significantly larger mean caliper and higher values for leaf biomass measures than trees growing in the compacted plots. ‘Celzam’ outgrew all other cultivars despite soil treatments and ‘Bowhall’ was unaffected by compaction, but did not produce aesthetically pleasing specimens.