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Bud development types as a new macroscopic marker of Norway spruce decline and recovery processes along a mountainous pollution gradient

Polák, T., Albrechtová, J., Rock, B.N.
Forestry 2006 v.79 no.4 pp. 425-437
forest trees, buds, growth and development, Picea abies, forest decline, air pollution, shoots, tree growth, montane forests, plant stress, defoliation, measurement, Czech Republic
A new macroscopic marker of decline and recovery processes in Norway spruce (Picea abies) based on proportions of bud development types was evaluated in 315 mature trees in two mountainous regions of the Czech Republic. This study was conducted in 1998 at 63 sites located in the Krusne hory Mts, which exhibited a wide range of damage corresponding to a gradient of increasing air pollution load (mainly SO2 and NOx) and the Sumava Mts, a relatively unpolluted area. Proportions of bud development types (regular buds, buds with growth potential and aborted buds) were found to reflect the current intensity of primary shoot formation in crowns as well as a capability to replace needle loss by formation of secondary shoots via differentiation of buds with growth potential. Using cluster analysis, the trees were classified according to the proportion of individual bud development types into one of three shoot growth categories: accelerated, stabilized or decreased shoot growth. Trees with accelerated shoot growth are characterized by intense production of assimilative organs and a small pool of viable buds with growth potential. Trees with stabilized shoot growth have high potential for crown recovery via activation of abundant buds with growth potential, and trees with decreased shoot growth have high rates of aborted buds, slow primary shoot formation and small pools of buds with growth potential. This new marker reflects well the forest recovery observed in areas with recent decreases in pollution loads. The results indicate that traditional macroscopic markers such as crown defoliation are less sensitive to the current status of tree crowns when compared with the proportion of individual bud development types. The potential of this new marker for forestry practice and tree physiology is discussed.