The goal of this study was to determine how different pruning techniques affect trunk movement on live oak subjected to hurricane force winds. Tree movement in wind on nonpruned trees was compared with movement on trees with crowns thinned, reduced, or raised. Twenty trees were blown using a wind generator up to 45 m/s (110 mph) maintained for 3 min. Each tree was instrumented with three orientation sensors at set heights along the trunk to measure its deflection. Thinning or reducing crowns significantly reduced upper trunk movement at all wind speeds, whereas raising did not. Lower trunk movement was not affected by pruning type. These data indicated that foliage and branches toward the top of tree crowns were largely responsible for trunk movement in straight-line wind with those toward the bottom less important. Trees that are reduced or thinned in the manner described could receive less damage in windstorms.

Branch diameter relative to the trunk diameter (aspect ratio) affected the extent of discolored and decayed wood in the trunk of seedling-propagated red maple (Acer rubrum L.) after branch removal. More discoloration resulted from removing codominant stems than removing branches that were small compared to the trunk. Removing limbs that originated from lateral buds resulted in the same amount of discoloration and decay as removing suppressed limbs that were once the leader. This result provides indirect evidence that a small codominant stem suppressed by pruning techniques designed to slow its growth rate can result in a branch protection zone at the union. There was no relation between the presence of a bark inclusion and decay 4 years after making pruning cuts.

Five species of trees were measured in 12- to 27-year-old parking lots in north-central Florida, U.S. Tree species evaluated were Chinese elm (Ulmus parvifolia Jacq.), live oak (Quercus virginiana Mill.), sycamore (Platanus occidentalis L.), shumard oak (Q. shumardii Britton), and laurel oak (Q. laurifolia Michx.). Tree growth in the parking lot planting zones was reduced as the surface area of nonpaved surface was reduced for all trees except live oak. Regression models yielded significant relationships with prediction value between parking lot detail space openings and tree size, measured by diameter at breast height or by canopy radius. Normalization of the data within the site allowed for multiple site analysis. A method for generating similar data is introduced for development of regionally species-specific growth reduction multipliers. Those multipliers can be used to better meet long-term canopy expectations or to advocate for larger planting zones.

Lagerstroemia ´ 'Natchez' trees were topped, pollarded, or not pruned for 4 consecutive years. The first time trees were pruned in 1998, pollarding required more time than topping. However, the time required to top trees increased in each subsequent year; pollarding time remained the same for each year. Longitudinal sections through stems showed that barrier zones and decay extended farther behind heading cuts on topped trees 5 years after the initial pruning than with the cuts on pollarded trees. Trees in the topping treatment formed a visible, dark-colored barrier zone along the cambium present at the time of wounding, averaging 74 cm (2.5 ft) in length, originating from the heading cuts made through 4- to 5-year-old wood. Barrier zone length on pollarded trees was only 1.8 cm (0.7 in) behind the original heading cuts through 2- to 3-year-old wood. Topping trees resulted in a sixfold increase in the volume of wood contained in dead stubs in the canopy compared to pollarding trees. Topping increased the need for cleaning the canopy of dead branches. A collar formed at the base of sprouts that were less than 0.64 the diameter of the largest sprout 5 years after the original heading cuts on trees in the topped treatment.

Propagation containers modify root systems, which affect post-planting anchorage in reforestation efforts, but little is known about larger-sized trees typical in urban landscapes. The main goal of this study was to determine the role of root morphology on postplanting anchorage and growth on Swietenia mahagoni (L.) Jacq., a common landscape tree in warm climates. Two propagation container types, two larger container types, and root pruning were used to impose various root morphologies inside root balls. Anchorage was evaluated by winching trees at two bending stresses to simulate wind events. Interaction between propagation container type and root pruning when the liner was shifted into 3.8 L containers prevented either from consistently influencing anchorage. Trunk tilt (i.e., instability) immediately following pulling was greatest for trees with the most root CSA deflected by the 9.5 L container; trees with straighter main roots in the root ball were better anchored. Researchers found seven root attributes associated with trunk tilt during winching tests that evaluated anchorage. Results show that straight roots in the root ball were associated with stable trees after planting into field soil.