Journal Article

Visible and microscopic needle alterations of mature Aleppo pine (<i>Pinus halepensis</i>) trees growing on an ozone gradient in eastern Spain

Minna Kivimäenpää, Sirkka Sutinen, Vicent Calatayud and María José Sanz

in Tree Physiology

Volume 30, issue 4, pages 541-554
Published in print April 2010 | ISSN: 0829-318X
Published online February 2010 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/tpq012
Visible and microscopic needle alterations of mature Aleppo pine (Pinus halepensis) trees growing on an ozone gradient in eastern Spain

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Visible injuries and 42 microscopic features of tissue and cell structure were quantified in needles of mature Aleppo pine (Pinus halepensis) growing at four field sites located on a natural ozone gradient in eastern Spain. Principal component analysis was used to find out if the forest sites differed from each other, to determine the reasons for the site differences and to evaluate the relations between the parameters studied. In previous-year needles, the first principal component (PC) was described by changes typical of long-term ozone stress: high occurrence of microscopic changes indicating increased defence and faint chlorotic mottling, but low occurrence of ultrastructural changes related to photosynthesis and its storage products. The second PC was described by needle ageing or ontological senescence. Statistical differences between the sites in terms of ozone stress were found and were in line with measured ozone concentrations and the values of the ozone exposure index, AOT40. Symptoms of ozone stress were mild, i.e., not related to severe tissue damage. Results suggested that the faint chlorotic mottling can be attributed to certain forms of condensed tannins or small chloroplasts. In addition, a coastal site differed from mountainous sites by having a more mesomorphic needle anatomy.

Keywords: forest health monitoring; needle anatomy; principal component analysis; ultrastructure

Journal Article.  8705 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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