Anatomical and Morphological Changes in Scots Pine and Siberian Larch Needles Under Impact of Emissions From a Large Aluminum Enterprise

Abstract

Species-specific anatomical and morphological changes of Scots pine and Siberian larch needles were studied at different levels pollution by aluminum smelter emissions. Anatomical parameters were found to change non-linearly in polluted needles as a result of pathological exposure to pollutants. In pine, negative anatomical changes include the following: reduction of the cross-sectional area of needles, central cylinder and conductive bundles, reduction of the thickness of the external tissues and mesophyll, reduction of resin channels and a decrease in their diameter. At a critical level of pollution, when the content of pollutants in pine needles reaches maximum values, certain changes in anatomical parameters in the remaining green needles are presumably adaptive. In larch needles at low, moderate and high levels of needles pollution, the anatomical changes found can be classed as adaptive – this is an increase in needles mass, thickness and width, thickness of the epidermis, mesophyll, cross-sectional area of needles. Larch needles, even at a critical pollution level, show no significant anatomical abnormalities. Negative morphological changes of pine include a decrease in the size of needles and shoots, their mass and the number of needles on shoots, in larch – a decrease in the length of needles and shoots, the number of brachiblasts. The results obtained suggest that indicators of the development of pathological processes in both pine and larch exposed to pollution are changes in the number of visual and morphological parameters of tree needles and shoots. Both showed a high level of correlation with the content of pollutants in the needles.