Prune roots of trees/shrubs before planting: freshwater wetlands
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
Background information and definitions
Plants can be stressed by the process of planting into a new site. Pruning before planting can encourage the growth of new, nutrient-assimilating feeder roots close to the plant: within the zone of roots that will be moved with the plant (Swackhamer & Sellmer 2007). It can also make planting process quicker and easier (Allen & Kennedy 1989).
To be summarized as evidence for this action, studies must have explicitly compared the performance of pruned and unpruned plants. Studies that simply report the performance of pruned plants are not summarized here. Studies do not have to be in flooded/saturated soils, as long as they involve wetland-characteristic species.
Allen J.A. & Kennedy H.E. (1989) Bottomland Hardwood Reforestation in the Lower Mississippi Valley. USFWS/USDAFS Report.
Swackhamer E. & Sellmer J. (2007) Transplanting or Moving Trees and Shrubs in the Landscape. Available at http://extension.psu.edu/transplanting-or-moving-trees-and-shrubs-in-the-landscape. Accessed 9 December 2019.
Supporting evidence from individual studies
A replicated, controlled study in 1988–1990 in up to five created freshwater wetlands in eastern Massachusetts, USA (Jarman et al. 1991) reported that pruning the roots of red maple Acer rubrum saplings before planting increased their survival rate. Statistical significance was not assessed. After approximately 1–2 years, saplings with roots pruned “several months” before planting had a >75% survival rate, compared to <25% for unpruned saplings. Methods: In the late 1980s, red maple saplings saved from destroyed wetlands were planted in up to five newly created wetlands (excavated from uplands, connected to natural wetlands, planted with herbs and shrubs as well as red maple). The roots of some saplings were pruned before planting. The study does not report the number of saplings planted, the precise number of wetlands planted with red maple, or precise dates of planting and monitoring.Study and other actions tested
A replicated, randomized, controlled study in a laboratory in Tennessee, USA (Farmer & Pezeshki 2004) found that pruning the roots of Nuttall oak Quercus nuttallii seedlings before planting had no significant effect on their survival or growth after 108 days. Pruned and unpruned seedlings had statistically similar survival rates 108 days after planting (data not reported). Pruned seedlings also grew in height by a statistically similar amount (lightly pruned: 8 cm; heavily pruned: 10 cm) to unpruned seedlings (13 cm). However, over a shorter period (72 days after planting) lightly pruned seedlings grew less (5 cm taller) than unpruned seedlings (10 cm taller). Heavily pruned seedlings grew 7 cm taller over this period. Methods: On an unspecified date, 144 nursery-reared Nuttall oak seedlings (approximately 25 cm tall) were planted in pots in a laboratory. Immediately before planting, 48 seedlings received each pruning treatment: light (25% of root removed), heavy (75% of root removed) or none. After planting, half of the seedlings were intermittently flooded (10 days flooded/10 days freely drained) whilst half were always “well watered”. Seedlings were monitored for up to 108 days after planting.Study and other actions tested