The temporal dynamics and spatiaJ distribution of heat production by inflorescences of Arum maculatum L. were investigated by infra-red thermography. Two centres of he^t production, tbe appendix and the male flowers, and three tbermogenic phases, two of tbe male flowers and one of tbe appendix, could be obser\ed. On tbe first day of flowering, when the spatbc was still firmly closed, the male flowers became tberniogenic ( = first thfrmogenic phase of tbe inflorescence) and reacbed surface temperatures of 4-l-8

Decline phenomena in two spruce (Piceaabies (L.) Karst.) forests in different locations in Austria are described on a biochemical and ultrastructural level. Needles of declining trees (canopy state class 3 or 4, more than 40% needle loss, and visible needle chlorosis) are characterized by loss in chlorophylls, xanthophylls, and carotenes in older needles, with α-carotene and chlorophyll a showing strongest depressions. Total chlorophyll concentrations in visibly yellowed needles range below 1 mg•g−1 dry weight, whereas green needles contain more chlorophyll. All trees included in this study fit in one common model with respect to the pigment changes, suggesting that needle yellowing is a consequence of secondary reactions rather than an initial state of decline. Depressed α-carotene/β-carotene ratios are associated with electron-microscopically visible thylakoid reductions, and needles with lightened plastoglobuli exhibited higher neoxanthin contents. Apparently healthy trees (canopy state class 1 or 2, less than 40% needle loss) in the declining stands were used to correlate nutrient status and antioxidant responses (glutathione and ascorbic acid concentrations), respectively, versus chlorophyll contents to reveal primary contributors to decline symptoms. At one of the investigated sites chlorophyll concentrations are significantly correlated to nitrogen, calcium, and potassium contents of the needles. At the second site, correlations of glutathione levels to chlorophyll concentrations point to a considerable contribution of oxidative stresses to decline symptoms of the spruce stands in the second location, where nutritional factors do not seem to play a dominant role in the initial stages of the needle yellowing.

SUMMARYThe study presents itivestigatiotis of epicutictilar wax morphology on spruce needles (Picea ahies (L.) Karst.) performed by ambient tetnperatute scanning electron tnicroscopy. To use alterations to epicuticular wax morphology as a successful tool in forest damage research, it is necessary to distinguish environtnetital influences and artefacts from comtnon pollution effects. The present paper sutnmarizes observations of alterations to epicuticular waxes independent of poUutioti eflects, recorded iti various field studies. These observatiotis are supplemented by controlled experiments to investigate wax alterations owing to solvents and tneehanieal itijuty. Eissures in tlie antechamber wax were the result of tieedle shritikage duritig drying. Wax alterations, where only the antechamber wax was afTected by a continuous loss of the structural integrity of wax tubes, were classified as storage artefacts since they occurred exclusively on needles stored iti air-tight glass vials and were unrelated to needle age, sampling site or pollution influence. Such wax alterations were never observed in tieedles stored iti airpermeable paper bags. Mecbartical itijury also resulted in severe morphological alteratiotis to epicuticular wax structures. The wax tubes on the surface as well as in the antechamber were squashed and flattened. On smoothed and squashed wax layers a sif^niHcant regrow tb of wax tubes was occasiotially observed, unrelated to needle age. Though the tubular fortn of the re-crystallized waxes was sitnilar to those originally presetit on the surface, the tube diameters were tnucli wider. Sitice redeveloped wax tubes also occurred oti dead needles which bad been artificially itijured, this process could be classified as re-crystallization analogous to wax re-crystallization out of solvent extracts. The re-crystallization took place within 48 h after the mechanical itijury occurred. The implications of the reported wax alterations for a successful use of epicuticular wax morphology as a bioindicator are discussed.

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