Abstract
AbstractCurrent UK guidance suggests that a ‘rootable’ soil profile of at least 1.0 m depth should be sufficient to allow adequate rooting of the majority of tree species in a range of soil types and climatic conditions [Arboricultural Journal (1995) vol. 19, 19–27]. However, there is some uncertainty as to what constitutes a loosened soil profile in terms of penetration resistance. In this study the root development of Italian alder, Japanese larch, Corsican pine and birch was assessed after 5 years of tree growth. These data were compared to penetration resistance measured using both a cone penetrometer and a ‘lifting driving tool’ (dropping weight penetrometer). Tree root number and percentage were significantly reduced by increasing soil penetration resistance measured with both the cone penetrometer (P < 0.050) and the ‘lifting driving tool’ (P = 0.011 and 0.008 respectively). The vast majority of roots were recorded in soils with a penetration resistance of less than 3 MPa (90.7%) with a significant amount in the less than 2 MPa class (70.2%). Root development of Italian alder, Japanese larch and birch all showed a similar pattern, but Corsican pine appeared to be capable of rooting into more compact soils. The ‘lifting driving tool’ can be used as an alternative measure of soil penetration resistance. This equipment is more cost effective, easier to use and capable of measurements at a greater depth than the cone penetrometer. The majority of Japanese larch and birch roots (84.3%) were recorded in soils where it took less than 15 impacts to penetrate one 10 cm soil depth increment. The modelled data also suggest that a penetration resistance of 2 and 2.5 MPa relates to 10 and 15 impacts respectively.
Highlights
Soil compaction is often responsible for the poor performance or failure of tree planting in both land regeneration projects and within existing woodlands
Current UK best practice recommendations are that generally a ‘rootable’ soil depth of at least 1.0 m should be provided for successful woodland planting; this guidance covers the range of species, soil types and climatic conditions that would normally be expected within the UK (Moffat & McNeill, 1994; Moffat, 1995)
The Corsican pine data showed a much higher degree of variability than those for the other species making it difficult to draw any real conclusions about the ability of the roots of this species to penetrate into the different penetration resistance classes
Summary
Soil compaction is often responsible for the poor performance or failure of tree planting in both land regeneration projects and within existing woodlands. Compaction occurs as a result of soil stripping, storage and placement and from the trafficking of heavy machinery during restoration and timber harvesting. It alters the moisture regime of the soil and can impede the growth of roots so that the tree is not able to draw water or nutrients at depth; poor root development can make mature trees more susceptible to wind-throw. It is essential that the values obtained using a penetrometer can be related to the potential root development both to save the costs involved in unnecessary cultivation and to ensure that cultivation has been successful This is important in the case of tree establishment where there is only one real opportunity for cultivation as the trees are likely to be present on the site for a considerable number of years and any adverse effects of compaction may not be observed until several years have passed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
