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Soil digging

Dig some holes to reveal the soil profile.  Add to this knowledge as opportunity arises, eg excavating rides, transplanting trees, soil erosion.

What’s  special  about  woodland  soil?
        A  practical  guide  for  owner/ managers

 When we talk about most aspects of the woodland- soil is mentioned.  Why?  Because soil is what plants grow in.  It governs the forest ecosystem and is thus an important indicator of woodland health.  Soil can also be a good guide of the age of your woodland, indicating whether it originates from the prehistoric wildwood or is planted on what was previously land used for agriculture. This may be significant, for example whether nutrient levels are too high or too low and mycorrhizal fungi are present to stimulate tree growth.

It’s amazing how often the soil is abused; through ignorance, clear cutting, clearings that are too big letting in too much light and air, trampling by human feet, compaction by machinery, fuel spillage, acidification from conifers (whereas broadleaves tend to sweeten the soil), impervious agricultural pan, agricultural run-off, etc, all of which damage plant roots and can take decades to recover.  So watch out.

What to look for?  Start by looking at the Geological Survey for your area.  This shows the drift material indicating where the soil came from and thus its type.  We must measure the depth of the soil profiles as they vary enormously, measure the acidity and alkalinity (pH) and the mineral nutrient content (garden centres are a good place to look for basic equipment).

Map the soils in your woodland as an extension of the Habitat Jigsaw.  Go into your woodland and dig holes to reveal the top and sub-soil. (usually spade depth).  Observe the colour and texture and how thick are the layers (where it came from gives a clue).  If necessary seek advice.  Test the pH, note how far the tree roots penetrate; and whether mycorrhiza and Honey fungi (Armillaria spp.) are present.  Transplanting young trees provides a good opportunity to do this.  As the soil types become evident, draw a map (example opposite).  describe the geography of each area eg. wet/ dry, calcareous (limestone), shallow/ deep, north facing, etc.  The jigsaw pieces will reflect the flora (including trees) of each area; bramble for example, is one of the few plants to grow on badly compacted or polluted soil.

Soil is what plants grow in  and must therefore be regarded as a living thing.  It’s alive and is the key to a healthy woodland.  It contains more life than all the woodland above ground and is a delicately balanced chemical and biological ecosystem- from minerals and bacteria to worms and fungi that is not fully understood.  Soil has many functions -
* Provides stability - enabling the tree to stand up-right.  When the root plate is too small, eg shallow soil over clay or rock, trees become susceptible to windblow as they grow.
* Holds nutrients - in the form of organic (humus- decaying plant material) and inorganic (principally nitrogen, phosphorous and potassium).  It is the mycorrhizal fungi that make these nutrients available to the plants, especially trees, in exchange for carbon made by photosynthesis.  This carbon is retained in the microbial biomass and plant residues in the soil.  The loss of the biomass releases this carbon back to the atmosphere.
* Retains moisture - Soil holds rainwater like a sponge slowly releasing it to plants and to the atmosphere.  Decaying wood on the forest floor also holds significant amounts of moisture, especially on dry sites- acting as a seed bed for ferns, trees and fungi, which take root in the soil.  Leaf litter is the perfect mulch protecting the soil from drying out.  As a result damp woodland has a much richer flora than a dry, conversely dry is poorer.
* Produces humus - a chemical soup of decaying organic matter found in the topsoil.  Healthy woodland has plenty of it- the more decaying matter the more humus.  Fungi contribute by disposing of great quantities of leaves, branches and twigs that fall on the soil, contributing to the humus on the woodland floor.

The purpose of this FAQ is to provide a start, enabling you to enquire further.  Soil is a huge subject that is frequently overlooked and is a particularly difficult question to answer, as a review of the literature will reveal.  Comment on this page is therefore especially welcome.  I am especially grateful for the advice and comment given by Bob, Lucy and Paul.  Reference has been made to- Soil by G. V. Jacks 1954



soil map

soil a


bramble protection

Soil survey map made by the owner showing the diversity of soil communities.  Keep a record of each hole for ease of reference.








Leaf litter is perhaps the best protection for the soil, preventing it drying and recycling nutrients.




The topsoil (dark) referred to as the A horizon overlying the subsoil, the B horizon, clearly visible.




Nature provides decaying leaves to protect the soil from drying and a light cover of bramble to protect seedlings just where there is some overhead light.