The nutrient regime of forest soils is one of the major abiotic influences on forest strand development. Its assessment is therefore essential to ecologically-appropriate silviculture. This is reflected in the new system of "Ecological Site Classification" being developed by the Forestry Commission. Soil nutrient regime will be one of the three main descriptors of site quality, alongside climate and soil moisture regime. A programme of simultaneous sampling for soil chemistry, humus type and ground vegetation species composition was carried out at 70 forest sites throughout mainland Great Britain. The intention was to derive a quantified definition of soil nutrient regime and to demonstrate that both ground vegetation species composition and humus type could aid its assessment in the field. Soil samples were subjected to laboratory analysis to measure the following nutrient parameters:- pH, loss-on-ignition, moisture content, total phosphorus and the availability of nitrogen, phosphorus, calcium, magnesium and potassium. Nitrogen was determined in the form of mineral components both before and after an aerobic incubation. Vegetation descriptions were treated by the assignment of indicator values to each species and the calculation of an abundance weighted site mean indicator value. Initially the R and N values proposed by Ellenberg were adopted. The data collected were analysed statistically using multivariate techniques. pH and nitrate-nitrogen availability emerged as the most important components of soil nutrient regime. Most other nutrients were positively correlated with these. A single composite gradient of soil nutrient regime, incorporating all parameters, was defined. It was shown that the weighted mean site Ellenberg R value was correlated with this gradient with r = 0.89. The correlation could be enhanced to r = 0.94 by the use of internally-generated species indicator values. Humus type [mor, moder, mull] was also found to be related to site position on this gradient. Both vegetation species composition and humus type were thus shown to be effective for the field assessment of soil nutrient regime as defined. A division of the gradient into five classes of soil nutrient regime was proposed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:663940 |
| Date | January 1998 |
| Creators | Wilson, Scott McGavin |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11588 |
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