Department of Physics, Chemistry and Biology (IFM)
Results
General results
47 818 individuals of 124 saproxylic beetle species were caught in the traps.
99 species were obligate saproxylic, and 25 species were facultative saproxylic.
9 species were red-listed, and 19 species were classified as nature value indicators.
Differences within and between the type and the age of wood
The largest numbers of species and individuals were found in standing wood with bark, and the lowest in debarked logs (Figure 1).
The number of individuals was 367 times higher in standing wood with bark than in debarked logs. There were 4.3 times more species emerging from standing wood with bark than it was from debarked logs.
The highest abundance of individuals and species was noted on one-year-old wood (debarked or left with bark in year 2022), while the lowest on four-year-old wood (debarked or left with bark in year 2019) (Figure 2).
There were 307 times more individuals emerging from one-year-old wood than from four-year-old wood. The number of species was 2.5 higher in one-year-old wood than in four-year-old wood.
There was a significant interaction between age and type of wood, suggesting that the number of species in standing trees with bark decreased with age, while debarked logs remained constantly low over time (Figure 3 and Figure 4).
Figure 1. To the left: Number of species found in traps installed on different type of wood. To the right: Number of individuals caught in traps installed on the three types of wood. L = debarked logs. R = reference, logs with bark. S = standing trees with bark. Letters A, B and C indicate significant differences between the different types of wood.
Figure 2. To the left: Number of species found in traps installed on wood of different ages. To the right: Number of individuals caught in traps installed on wood of different ages. 4 years since debarking (4-year-old wood) = debarking (or leaving with bark in this area) took place in 2019, 3 years since debarking (3-year-old wood) = debarking (or leaving with bark in this area) took place in 2020, and so on. Letters A, B, C and D indicate significant differences between ages.
Figure 3. Differences in number of individuals (log(N+1)) depending on years since debarking and type of wood (L = debarked logs, R = logs with bark, S = standing wood with bark). There were no traps installed on logs with bark (reference, R) from years 2021 and 2022 (2 and 1 year since debarking).
Figure 4. Differences in number of species depending on years since debarking and type of wood (L = debarked logs, R = logs with bark, S = standing wood with bark). There were no traps installed on type undebarked log (reference, R) from years 2021 and 2022 (2 and 1 year since debarking).
Species composition
Comparison of standing wood with bark and debarked logs of all ages showed a significant difference between them. Species from standing wood with bark were similar to each other, whereas those from debarked logs varied a lot (Figure 5).
Comparing the all the oldest types of wood (managed in 2019 and 2020), including logs with bark (reference), showed that both types of logs were not significantly different from each other, while undebarked standing wood significantly differed from them (Figure 6).
Comparing only standing wood with bark of all ages showed that the species composition changed significantly over time and the difference was largest between one- and four-year-old wood (2022 and 2019). There was no significant difference in species composition between all debarked logs of all ages (therefore not illustrated) (Figure 7).
Figure 5. NMDS showing the species composition of saproxylic beetles on wood of type S (standing wood with bark) and L (debarked log). Big red circle shows big dispersion of species, indicating their dissimilarities. Small black circle indicates that species were close, similar to each other.Figure 6. NMDS showing the saproxylic beetle species composition of three- and four-year-old wood (managed under years 2019 and 2020) of type S (standing with bark), L (debarked log) and R (reference, log with bark). The big red oval shows that species found on debarked logs greatly differed from each other. The small green oval showing species found on reference logs with bark is contained within the red one, which means that species, althoug less varied from each other, were similar to those found on debarked logs. The small black oval shows that species found on standing wood with bark differed from those from logs, and there were similar to each other.Figure 7. NMDS showing the saproxylic beetle species composition of standing wood with bark of all ages. 2019 = four-year-old wood, 2020 = three-year-old wood, 2021 = two-year-old wood and 2022 = one-year-old wood. The bigger the area of an oval is, the more varied species composition there was, meaning that the species found in the traps were quite random. Ovals overlapping shows similarities between the composition of species found on wood of different ages.
