Development of three underplanted hardwood species 7 years following midstory removal.

摘要

We evaluate the effect of four midstory removal (no removal, 1/3 removal, 1/2 removal, and complete removal) and two understory removal (no removal, complete removal) intensities on underplanted seeding size and survival after seven growing seasons. The study was conducted in a mixed-hardwood riparian forest. The underplanted species were cherrybark oak (Quercus pagoda Raf.), water oak (Quercus nigra L.), and yellow-poplar (Liriodendron tulipfera L.). Seven-year survival of cherrybark oak, water oak, and yellow-poplar was higher in the complete midstory removal treatment than in the no midstory removal treatment. Height and basal diameter were significantly greater in the complete midstory removal treatment than in 1/2, 1/3, or no removal treatments. Understory removal had no effect on yellow-poplar and only marginally increased water oak survival and cherrybark oak seedling size. Species trends indicated that the growth of yellow-poplar following complete midstory removal surpassed that of both cherrybark and water oak. Mean survival of yellow-poplar was lower than cherrybark or water oak survival in all treatments. Results suggest underplanting and complete midstory removal may be effective at establishing large advance reproduction in mixed hardwood riparian forests. Findings also suggest that complete midstory removal created favorable conditions for the continued survival and growth of underplanted seedlings through seven growing seasons. If oak reproduction is considered to be sufficiently competitive on reaching a height of 137 cm (4.5 ft), the average cherrybark and water oak seedlings in the complete midstory removal treatment exceeded this minimum and may be released following the fifth growing season after underplanting.