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Tomáš Čihák, Tomáš Hlásny, Radka Stolariková, Monika Vejpustková and Róbert Marušák

Abstract

The Small-leaved lime (Tilia cordata Mill.) is currently not commercially important species, therefore the knowledge of biomass partitioning in a tree is rather incomplete. Moreover, lime biomass is estimated mostly using biomass functions designated for other species, without the knowledge of limits of such a use. For these reasons, we developed functions for the estimation of lime biomass in the aboveground woody parts. The functions were parameterized using 81 tree samples collected in two plots in the Czech Republic. In addition, we compared the biomass estimates produced by our functions with estimates produced by a function for beech, which have been obviously used as a surrogate for missing lime models in the Czech Republic and Slovakia.

On average, 78% of lime aboveground biomass was found to account for tree stem, 20% for branches and 2% for stump. Average biomass density was 374 kg m−3 and no significant differences between tree compartments were found. Accuracy of all models in terms of the Root Mean Square Error (RMSE) significantly differed between tree diameter classes; in case of total aboveground biomass, the RMSE was ca. 20% of the average biomass weight in a given class up to a diameter of 45 cm, and then it rose sharply. The RMSE was higher in case of compartments with variable dimensions, such as branches and stump. RMSE was slightly higher in case of estimates produced using a beech-specific function than using that developed in the current study (average RMSE 27.95 and 29.42%, respectively); at the same time, beech-specific function overestimated lime stem biomass by ca 12%. The almost equal RMSE implies the usability of both parameterisations for lime biomass estimation, though the correction of the mentioned overestimation should be applied.

Open access

Jozef Pajtík, Tomáš Čihák, Bohdan Konôpka, Katarína Merganičová and Petr Fabiánek

Abstract

Although tree mortality is an essential process in forests, tree death still remains one of the least understood phenomena of forest development and dynamics. Therefore, we focused on annual mortality rates together with annual felling rates in the Slovak and Czech forests. We used data from the long-term national monitoring (periods of 1988–2017 in Slovakia and 1992–2017 in the Czech Republic). More than 24.6 thousand trees were assessed together in both countries. We calculated mortality and felling rates derived from two variables: basal area and number of trees. For these purposes, we selected five tree species/genera, specifically: Norway spruce, pines, European beech, oaks and common hornbeam. We recorded large inter-annual fluctuations of mortality rates in all tree species/genera. In both countries, spruce and pines had the highest mortality rates, while beech had the lowest mortality rates. Confrontation of long-term climatic data (especially annual precipitation totals) with mortality data indicated that drought was probably the most relevant factor causing tree death. On the other hand, no significant temporal trend, either increasing or decreasing, in tree mortality was found for any tree species/genera. As for all five selected tree species/genera together, significantly higher mean annual mortality rate derived from the number of trees was found in the Czech Republic (1.09%) than in Slovakia (0.56%). This finding indicates that tree mortality is often caused by combined effects of external unfavourable factors and competition pressure in forest stands.