Action: Use prescribed fire after tree planting
- Two of four studies (including one replicated, randomized, controlled study) in Finland, France and the USA found that using prescribed fire after replanting increased the survival and sprouting rate of planted trees. One study found fire decreased planted tree size and one found no effect of prescribed fire on the size and survival rate of planted trees.
Prescribed fires are used in the maintenance or restoration of habitats historically subject to occasional ‘wildfires’ that have been suppressed through management. Using prescribed fires in such habitats can improve the establishment of the planted tree seedlings.
Supporting evidence from individual studies
A replicated, controlled study in 2001-2008 in boreal forest in Finland (1
Den Herder, Kouki & Ruusila 2009) found no effect of burning on the height or mortality of tree seedlings. Tree heights were similar in burned and unburned plots for silver birch Betula pendula (50-70 cm), rowan Sorbus aucuparia (45-50 cm) and Eurasian aspen Populus tremula (35-40 cm), as were their mortality rates (54-55%, 8-12% and 27-30% respectively). Ten seedlings of each species were planted in 2002-2003 in each of three burned and three unburned plots (10 ×15 m). The burn treatment was applied in 2001. Data were collected in 2002-2008.
A replicated, controlled study in 1998-2006 in temperate forest in Louisiana, USA (Haywood 2009) found that prescribed fire decreased the height and basal area of longleaf pine Pinus palustris saplings. Longleaf pine height (March burn: 7.7 m; May burn: 8.7 m; July burn: 8.6 m; control: 9.1 m) and basal area/tree (March burn: 72; May burn: 94; July burn: 92; control: 116 cm2) were lowest following a burn in March, intermediate and similar following burns in May and July and highest in control plots. Data were collected in 2006 in three plots (0.07 ha) of each treatment: a burn in March, May or July (prescribed burn in 1999, 2001, 2003 and 2005), and a control (untreated since 1998) treatments. Each of the 12 plots was planted with 196 longleaf pine seedlings in 1993-1994.
A replicated, controlled study in 1999-2005 in Mediterranean shrubland in California, USA (Holmes et al. 2011) found that prescribed fire increased sprouting in planted valley oak Quercus lobata saplings without affecting mortality. The number of new shoots/sapling was higher in burned plots (summer burn: 4.6; spring burn: 4.6; control: 0.8), while the mortality rate was similar between treatments (summer burn: 3%; spring burn: 4%; control: 0%). Data were collected in autumn 2005 in 8-9 blocks (72 m2) of each of: a summer burn (in 2003), a spring burn (in 2004) and control treatments, with an average of ten oak trees/block.
A replicated, randomized, controlled study in 2005-2006 in Mediterranean Aleppo pine Pinus halepensis woodland in France (Prévosto et al. 2011) found that prescribed burning increased the survival of planted downy oak Quercus pubescens and holly oak Q. ilex seedlings. In plots with woody debris, survival of downy oak (control: <0.1; burned: 0.8 seedlings/sowing point) and holly oak (control: 1.0; burned: 2.2) was higher in burned plots. In contrast, in plots without woody debris, survival was similar between treatments for both downy oak (control: 0.0; burned: 0.2) and holly oak (control: 0.7; burned: 1.2). Grass cover was similar between treatments in plots with woody debris (control: 17%; burned: 10%) and without (control: 22%; burned: 16%). Data were collected in 2006 in 16 plots (14 × 14 m). There were four control and four burned (prescribed fire in 2005) treatment plots with woody debris scattered in the plot, and four of each treatment where the woody debris had been manually removed. All plots were thinned in 2004 (from 410 to 210 trees/ha) and in November 2006 holly oak and downy oak were planted with three acorns spaced 1 m apart at each sowing point.
- Den Herder M., Kouki J. & Ruusila V. (2009) The effects of timber harvest, forest fire, and herbivores on regeneration of deciduous trees in boreal pine-dominated forests. Canadian Journal of Forest Research, 39, 712-722
- Haywood J.D. (2009) Eight years of seasonal burning and herbicidal brush control influence sapling longleaf pine growth, understory vegetation, and the outcome of an ensuing wildfire. Forest Ecology and Management, 258, 295-305
- Holmes K.A., Veblen K.E., Berry A.M. & Young T.P. (2011) Effects of prescribed fires on young valley oak trees at a research restoration site in the Central Valley of California. Restoration Ecology, 19, 118-125
- Prévosto B., Monnier Y., Ripert C. & Fernández C. (2011) Diversification of Pinus halepensis forests by sowing Quercus ilex and Quercus pubescens acorns: testing the effects of different vegetation and soil treatments. European journal of forest research, 130, 67-76