Tree growth after trenching and compensatory crown pruning

摘要: The roots of pin oak (Quercus palustris) trees were severed by trenching on 1, 2, or 3 sides the tree. distance between trunk and trenches was approximately equal to circumference. Half also received compensatory crown pruning. All survived significant dieback noted only that trenched sides. Generally, more extensive trenching, greater growth reduction dieback, longer persisted. Compensatory pruning increased twig for all treatments, but seems be most beneficial in reducing after severe root loss from trenching. Under certain circumstances absence other construction impacts, vigorous may able tolerate recover zone. Established sites are often subject mechanical damage site changes could eventually result their decline death. Damage system is difficult evaluate even when easily observed as an open trench obvious grade change. In situations, go completely unobserved if not evaluated until final landscaping completed, obscuring cause tree decline. Compacted soil just damaging systems direct (Ziza et al. 1980). Even carefully protected during construction, site, such drainage, can alter environment within It arborists separate combined effects many types treedamaging activities occur a predict effect its system. There little published research help specify how much must reasonable chance long-term survival. Industry practices use above-ground features dimensions protection zones. Branch spread (dripline) commonly used (Olson Wray 1979; Schoeneweiss 1982; Fazio 1992; Miller 1993 ). Trunk diameter (Morel 1984) height (Miller 1993) sometimes determine size While these guidelines helpful, they have been tested controlled studies. One purpose this experiment study resulting compaction, changes, factors. Specifications augering near called no closer than 8 12 cm each (8 in. inch) measured at breast [dbh, 1.4 m (4.5 ft) above ground level]. When specifications followed, occurred Neely 1993). trunk, reduced. No died Young stressed survive. practice compensate has years, value questioned. Pruning intended relieve stress rebalancing with reduced But nearly half lost single base trunk. cannot pruned extensively still retain natural form Removing number branches thought eliminate vital carbohydrate production reserves (Shigo 2nd 48 Watson: Tree Growth After Trenching Crown Materials Methods oaks palustris), 29 (11.4 in.) average dbh, Morton Arboretum Lisle, Illinois. planted groups 3, spaced 2 (6 straight line. Groups 15 (50 centers. Five incomplete (only trees). A 3rd adjacent group cases. good health start experiment. treatments assigned randomly. Trenches dug May 30, 1991. timed sudden leaves fully expanded, yet hardened-off. At time, expected severe. Trees (designated 1T, 2T, 3T, respectively) 1 (3 maximum depth machine. wide, extending 30 (1 ft ) 2.5 dbh. Each different treatment (Figure 1). circumference slight variations caused machine access spacing. refilled same (all horizons mixed) allowed settle naturally. traffic permitted site. installed control (treatment C) trees. controls (15 trees), so there would 5 replicates relative position (west end, center, east end) event affected growth. completed days (treatments 1TP, 2TP, 3TP trenches, respectively). commercial care firm, Hendricksen, Care Trees, do actual thinned moderately lateral tipped • Base