Action: Add lime to the soil after tree planting
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- One of two replicated, randomized, controlled studies in the USA found that adding lime before restoration planting decreased the survival of pine seedlings. The other study found no effect of adding lime on planted oak seedling growth.
Application of lime (rich in Calcium and Magnesium) is used to neutralize soil acidity and increase activity of soil bacteria. This may increase soil fertility and as result help the establishment of planted trees.
Supporting evidence from individual studies
A replicated, randomized, controlled study in 1991-1995 in a degraded temperate coniferous forest in Idaho, USA (Walsh & Redente 2011) found that lime addition before restoration planting decreased the survival of western white pine Pinus monticola planted seedlings. Survival rate was lower with lime (lime: 63-66%) than without lime (72-75%). The two treatments, a control and lime addition (at 11 x 103kg /ha) were applied in 1991 to eight plots (3 x 10 m) at each of two hilltop sites. All sites were fertilized with nitrogen, phosphorus and potassium at 112, 56 and 90 kg/ha respectively and were planted with western white pine trees, along with shrubs and grasses, before treatments in 1991. Data were collected in 1995.
A replicated, randomized, controlled study in 2004-2009 in temperate broadleaf forest in Pennsylvania, USA (Long, Brose & Horsley 2012) found no effect of lime addition on the growth of planted seedlings of northern red oak Quercus rubra. Seedling height (16-33 cm) and root-collar diameter (6.5-9.5 mm) were similar between treatments. Data were collected in 2009 in two plots (12.5 × 8.5 m) of each treatment: 0, 4.5, 9.0 and 13.5 x 103kg /ha lime application rates (applied in May 2004) at each of five sites. All plots were partially thinned (shelterwood harvest) within the past 12 years and were planted with northern red oak seedlings in April 2004.
- Walsh J.R. & Redente E.F. (2011) Comparison of Reclamation Techniques to Re‐establish Western White Pine on Smelter‐impacted Hillsides in Idaho. Restoration Ecology, 19, 141-150
- Long R.P., Brose P.H. & Horsley S.B. (2012) Responses of northern red oak seedlings to lime and deer exclosure fencing in Pennsylvania. Canadian Journal of Forest Research, 42, 698-709