Temporal variation and efficiency of leaf area index in young mountain Norway spruce stand |
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Authors: | R Pokorný I Tomá?ková K Havránková |
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Institution: | (1) Laboratory of Plants Ecological Physiology, Institute of Systems Biology and Ecology, Academy of Sciences of the Czech Republic, Poříčí 3b, 603 00 Brno, Czech Republic |
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Abstract: | Temporal variation of leaf area index (LAI) in two young Norway spruce stands with different densities was monitored during
eight consecutive growing seasons (1998–2005). We focused on: (1) LAI dynamics and above-ground mass production of both spruce
stands and their comparison, (2) leaf area duration (LADU), crop production index (CPI) and leaf area efficiency (LAE) evaluation,
and (3) thinning impact on the above-mentioned parameters. Also, we tried to deduce the most effective LAI value for the Norway
spruce forest investigated. The LAI values of both spruce stands showed a typical seasonal course. To describe the LAI dynamics
of the stand, we recommend taking LAI measurements within short time intervals at the time of budding and needle expansion
growth (i.e., in early spring) and close to the LAI peak, when the twig growth has been completed. The reason was that after
reaching the seasonal maximum, no significant differences between subsequently obtained values were found in the following
2 months. Therefore, we recommend this period for the estimation of seasonally representative LAI values, enabling the comparison
of various spruce stands. The maximum hemi-surface LAI value reached 12.4. Based on our results, the most effective LAI values
for maximum above-ground biomass production were within the range of 10–11. We found an LAI over these values to be less effective
for additional production of above-ground biomass. In forest practice, thinning intensity is mostly described by percentage
of stocking reduction. We want to show that not only thinning intensity, but also the type of thinning is important information.
The type of thinning significantly affected the stand above-ground biomass increment, canopy openness, stand LAI and LAI efficiency.
The stimulating effect of high-type thinning was observed; the LAE as well as the CPI increased. Low-type thinning had no
such effects on LAE increments compared to the high-type thinning with similar intensity.
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Keywords: | Biomass Leaf area duration Picea abies Thinning |
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