The dependence of mycorrhrizae in Sitka spruce roots, on the availability of phosphorus in serpentine and basaltic soils
The nature and occurrence of mycorrhizal associations, with particular reference to the anatomy, carbohydrate physiology, plant mineral nutrition and occurrence of ectomycorrhizae (ECM), is discussed. The ecology and forest relations of Picea sitchensis - the Sitka spruce concludes the literature review. Identification of areas of good and poor Sitka growth on related soils and the quantification of their ECM status, investigation of the effect of phosphate addition to Sitka seedlings in pots, subsequent and changes to their ECM status, and the effects of soluble aluminium on phosphate nutrition of Sitka seedlings, the collation of results and relation back to the field situation were carried out as experimental work. Field sites were identified and described in terms of geology, soils, field ECM status, forest productivity and nutrient status. Three pot experiments were carried out. The 1st investigated the effects of phosphate application on ECM Sitka seedlings in soil from the field sites; the 2nd investigated the effects of phosphate application to ECM and non-mycorrhizal (NM) seedlings in compost; and the 3rd investigated the affects of application of Al-citrate to ECM and NM seedlings in compost containing high and low levels of phosphate. The results obtained were described and discussed in the context of a model of the factors affecting plant response to the soil environment. The field ECM development representing a considerable drain on the carbohydrate economy of the field sites was to some extent duplicated in the greenhouse. The possible decrease in importance of this drain was illustrated by phosphate application, but was increased by addition of Al-citrate. A previously unrecorded ECM-enhanced uptake of Manganese was reported. The importance of phosphate in the soils under discussion was emphasised, and possible further work suggested.