Laboratory of Computational Ecology
Dynamics of ecosystem processes after local and mass windthrows in the broad-leaved forests. Project of RFBR # 20-04-00733.
Project of the Russian Foundation for Basic Research No. 20-04-00733. Leader: Larisa Khanina.
Title: Dynamics of ecosystem processes after local and mass windthrows in the broad-leaved forests.
Annotation of the Report 2021
In the second year of the project, field work was carried out in two sites of the mass windthrow which are located on the fluvio-glacial sands (Yagodnoye settlement, Ulyanovsk district, Kaluga region) and on the sandy loams (Nagaya village, Ulyanovsk district). There were taken (1) 225 wood samples from the trunks of eight tree species of varying degrees of destruction, (2) 120 soil samples on sands and sandy loams in sites of mass windthrow (under and next to logs of 8 tree species) and in background forest communities, (3) more than 350 samples of wood-dwelling aphyllophoroid basidiomycetes on dead wood of 8 tree species; and (4) amounts of deadwood and undergrowth was recorded on permanent sample plots established in 2010.
In the reporting period, we analyzed for the first time for 8 tree species (Quercus robur, Fraxinus excelsior, Tilia cordata, Acer platanoides, Ulmus glabra, Populus tremula, Picea abies and Betula pendula) the characteristics of bulk density, C and N content and pH values in wood at five decay stages; the wood decay rates of broadleaf tree species in natural conditions were evaluated for the first time. In general, for all samples, wood density did not correlate with trunk diameter, did not differ between tree species, and linearly significantly decreased with increasing decomposition stage. Species did not differ in N content, C/N ratio, but did differ in C content and pH value. Decomposition stages had a greater effect on wood characteristics compared to species identity. This was observed for all tree species and for all traits except for carbon content, which practically did not change during decomposition and averaged 45.8 ± 2.43 (sd)%. Trend analysis showed that the data mostly agreed well with the linear models: as the decomposition stage increased, the nitrogen content significantly increased, and the C/N ratio decreased. Change in pH was best explained by the quadratic model: the values during decomposition first decreased and then increased.
A method was proposed to calculate wood decomposition rates for data collected at a mass windthrow area. The difference in the rate of decomposition of trunks of different species, falling at the same time, is manifested in a different proportion of wood at different stages of decomposition in different species. We estimated this proportion by the area of wood at various decomposition stages on cross-sectional disks. Wood decomposition rates decreased in the order Populus > Tilia > Acer > Picea > Betula > Ulmus > Fraxinus > Quercus.
Preliminary results of the study of soddy-podzolic soils on sandy loams showed that in the area of mass windthrow, the cation exchange capacity and pH values were significantly higher than in the background area. We also observed a significant increase in specific respiration of the microbial community and a significant decrease in the response of the microbial community to the introduction of organic substrates (amino acids, carbohydrates, and phenolic acids) at the mass windthrow area. A small but significant difference was found between the sampling site (under or near the log) for most of the microbiological characteristics of the soil: under the log were lower values of the carbon of the microbial biomass and the respiratory responses of the microbial community to the introduction of most organic substrates.
To date, 53 species of basidiomycetes have been identified at the windfall site on the sandy loams. From them, 16 species of fungi were noted for the first time for the Kaluga Region. In the reporting period, identification of fungi collected in 2020 in the fluvio-glacial sands was finished. Based on fruit bodies, 100 species of basidiomycetes were identified on 8 trunks and 33 cross-sections of 8 tree species, of which 52 fungi species were rare for European Russia and 46 species were new for the Kaluga Region.
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