Master in Forest Science

Growth, photosynthesis and needles structure of silver fir seedling growing in different light conditions
Department of Forestry, Agricultural University of Poznan, Poland
General Botany Laboratory, Adam Mickiewicz University, Poznan, Poland

JODLA During my master study at the Faculty of Forestry, I was involved in research aiming to understand the ecophysiological performance of young firs (Abies alba) growing under varying degrees of natural shade. As part of fir reintroduction program in the Karkonosze Mountains (Poland), three-year-old seedlings were planted in five forest stands dominated by different tree species (Picea abies, Fagus sylvatica, Betula pendula, Pinus sylvestris and Larix decidua). Over four growing seasons, annual apical increments became progressively greater under the light permeable canopy of Larix, but remained stunned under the deep shade of Picea, while intermediate irradiance at other sites resulted in intermediate growth responses. Similarly, apical dominance ratio was positively influenced by irradiance. These two contrasting sites were subsequently used for ecophysiological comparisons. By performing gas exchange measurements and chlorophyll fluorescence monitoring we found out that fir seedlings under the Larix canopy had consistently higher photosynthetic rates throughout the day compared to those under Picea. Fir needles produced under Larix were thicker and contained more chlorophyll, carotenoid, and nitrogen on area basis suggesting that structural modification is a major component of acclimation to light. To verify this hypothesis I have investigated morphological, anatomical and ultrastructural traits of needles using different microscopic methods. On anatomical levels, needles produced under Larix had the traits typical for sun-acclimated ones, while those under Picea for shade-acclimated. Leaf mass to area ratio, palisade parenchyma thickness, the diameter of resin ducts increased, whereas width/thickness ratio and needle thickness/parenchyma thickness ratio decreased with increasing canopy openness. Similarly at an ultrastructural level number of thylakoids per granum was lower, whereas chloroplast section surface inversely, was higher at greater canopy openness. These structural changes reflect the ability of silver fir saplings to acclimate to different irradiance. Together with our results suggested that fir seedlings find best growth conditions under the relatively light permeable conditions indicating that stands dominated by light-demanding tree species are more suitable for transformation using silver fir seedlings.

Relevant publications:

“Growth, photosynthesis, and needle structure of silver fir (Abies alba Mill.) seedlings under different 
canopies”
Robakowski P., Wyka T., Samardakiewicz S., Kierzkowski D. 
Forest Ecology and Management 2, 211-227 (2004) Reprint

“Variation in structure of needles of silver fir (Abies alba Mill.) saplings growing under the canopies
of diverse tree species” Robakowski P., Samardakiewicz S., Kierzkowski D.
Polish Journal of Ecology 52, 563-568 (2004) Reprint

“Variation in ultrastructure of chloroplasts in needles of silver fir (Abies alba Mill.) saplings growing
under the canopies of diverse tree species” Kierzkowski D., Samardakiewicz S., Robakowski P.
Polish Journal of Ecology 55, 821-825 (2007) Reprint


Stem photosynthesis variability among different tree species
Laboratoire Ecologie Systématique et Evolution, University Paris Sud, France

10 picea01 Photosynthetically active tissues can be found not only in specialized organs like leaves but also other parts of plants like stems. Stem photosynthesis may be of particular importance during the winter season when leaves are absent in deciduous species. During my Erasmus study in France, I was participating characterization of photosynthetic traits of current year stems of six deciduous tree species, two evergreen tree species and ginkgo were compared. We measured gas exchange, chlorophyll concentration, nitrogen concentration and maximum quantum yield of PSII in stems both in summer and winter. A light-induced decrease in stem CO2 efflux was observed in all species. Despite observed photosynthetic rate variability, a unique correlation, based on our results and those reported in the literature, was found between gross photosynthetic rate and dark respiration rate. The photosynthetic rate decreased with stem mass per area and correlated to chlorophyll concentration and nitrogen concentration, both in summer and winter. The radial distribution of stem chlorophyll differed among species, but all species except ginkgo had chlorophyll as deep as the pith. In summer, the maximum quantum yield of stem PSII of all species was near the optimal value found for leaves. By contrast, the values were highly variable in winter, suggesting large differences in sensitivity to low-temperature photoinhibition. Our results highlight the interspecific variability of gross photosynthesis in the stem and its correlation with structural traits like those found for leaves. The structural correlations suggest that the selection of photosynthetic traits has operated under similar constraints in stems and leaves.

Relevant publication:

“Interspecific variability of stem photosynthesis among tree species”
Berveiller D., Kierzkowski D., & Damesin C.
Tree Physiology 27, 53-61 (2007) Reprint

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