Biological Indicators of Forest Dieback

  • David Evans

    Student thesis: Doctoral Thesis


    This study involved the determinations of the foliar levels of chlorophyll a and b and metal levels in the year 1, year 2 and year 3 needles of Sitka spruce. A survey was made of nineteen sites in the Afan 1 forest in South Wales. The results obtained indicates that there are two distinct types of site, namely good growth sites and poor growth sites. The poor growth sites were found to be at higher elevations.

    Further analyses of the results show that there is possibly an increased loss of nutrients from the trees at the poor growth sites. This may be due to increased pollution that may be present at the higher elevations.

    In 1987 a survey was made of the one year old epicormic tissues that were compared with the normal tissues at the 19 sites of the Afan 1 Forest There were no statistically significant differences in the levels of the chlorophylls or in any of the metals that were looked at.

    At the Afan 1 Forest there are observed pairs of trees that are growing quite close together, but they exhibit quite a marked difference in growth. One of the pair shows vigorous healthy growth, whilst the other is stunted and shows symptoms of decline. One such pair is found at Site 15. They are of the same age and from the same seed stock. It was found that over an eight month period, the stronger growing of the pair had significantly higher levels of chlorophyll a and b, potassium, calcium and magnesium. This may indicate increased leaching and foliar damage from the poorer growing of the pair.

    Three more pairs of trees together with their grafts were examined from sites' 1,5 and 6, for their levels of peroxidase enzymes. Peroxidase has been used to determine possible genetic differences in cultivars. The work yielded very little useful information.

    The SCOR-UNESCO equations have been widely used as a means of determining chlorophyll levels from plant extracts. A multivariate calibration method was used in conjunction with HPLC to determine the accuracy of these equations for determining the levels of chlorophyll and b. The results show revealed that the equations appear to be underestimating the chlorophyll a levels. Leading on from the HPLC work, a novel method for the separating a mixture of chlorophyll a and b was developed using packed column SFC. The method appears to be quite promising with its better resolution and faster analysis times as compared to FIPLC methods.

    Sitka spruce seedlings were grown in COIR (coconut husk) and were used in and were used in a central composite design to determine the effects of cadmium and copper, both singly and in combination would have upon their growth. Response surface methodology was used to determine the effects and it was found from the experiment that high levels of cadmium appeared to have an effect upon the elongation of the needles of the new shoots.
    Date of AwardDec 1992
    Original languageEnglish

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