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Dynamika růstu buku lesního (Fagus sylvatica L.) ve smíšeném lese a monokultuře ve Východních Karpatech
Vyčítalová, Hana
The study observes the difference in the growth dynamics of common beech (Fagus sylvatica L.) in monocultures and in stands with admixture of conifers like Norway spruce (Picea abies L.) and/or Silver fir (Abies alba Mill.) in the Eastern Carpathians. Point dendrometers and soil humidity sensors were used for measurement of tree growth and water availability that took place near the Râșca in the Suceava region. Out of the growing season, hemispherical ("fish-eye") images were also taken to evaluate canopy openness. Mixed models were used for the statistical evaluation of the data. Negative effect of increasing the percentage of conifers in the stand on growth and the maximum growth rate of beech was found insignifficant, which give an evidence of beeches strong competitive ability in habitats with favorable conditions. However, a negative effect of a higher admixture percentage of conifers on the availability of water in the soil was signifficant, probably due to higher interception, which indicates possible problems when growing beech with a high admixture of conifers in drought-prone locations. The growth rate was highest at the turn of June and July, which refers to the dependence of beech growth dynamics on the solar cycle and indicates that drought could have the strongest negative impact on growth in the period around the summer solstice. On the basis of the obtained results, beech silviculture could be recommended with only a small admixture of conifers, and the admixture of other deciduous trees should be preferred in order to reduce the interception of the stand
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Vliv smíšení porostu na dynamiku růstu borovice lesní (Pinus sylvestris L.) ve Finsku
Vyčítalová, Hana
Mixed stands excel in their species richness and they theoretically have a better precondition for coping with disturbances than monocultures. On the other hand, there is interspecies competition, which may result in the oppression of individual species in the ecosystem. A total of 12 research plots in the province of North Karelia (Finland) were selected to approximate the effect of forest mixing on the growth of Scots pine (Pinus sylvestris L.). In growing season 2018, stem volume changes and drought stress responses were observed in monocultures and with the admixture of one or both of the species Norway spruce (Picea abies L.) and Silver birch (Betula pendula Roth.). The measurement of volume changes was performed using point dendrometers installed on individual pines, the temperature and soil moisture were monitored by a TMS-4 sensor located in the soil in the middle of each research area. It was found that in all cases, Scots pine grew only in dependence on rainwater, not groundwater. It was discovered that individuals in monoculture grew up to twice as much as in both types of mixed stands. They also showed a better ability to saturate the tissues with water after it had been spent for transpiration during the July drought. In August, however, the response to drought stress was comparable in monocultures and mixed stands. The measured results show that interspecific competition may have a negative effect on the growth and drought tolerance of Scots pine in the short term. However, at a time of escalating extreme climate events around the world, this issue needs to be further explored in order to create optimal conditions for the growth of future forests.
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