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 2020

     The aim of the project is to assess the dynamics of ecosystem processes occurring after isolated and mass windthrows in temperate deciduous forests. The study area is the Kaluzhskie Zaseki State Nature Reserve where solitary tree falls often occur and a catastrophic windthrow was happened in 2006. In the first year of the project, field work was carried out on the site of a mass windthrow which is located on the fluvio-glacial sands (Yagodnoye settlement, Ulyanovsk district, Kaluga region). There were taken (1) 182 woody samples from fallen logs of eight tree species at different stages of wood decomposition; (2) 50 soil samples beyond and close to fallen logs of different tree species and 10 soil samples outside the mass windthrow; (3) more than 250 specimens of wood-dwelling aphyllophoroid basidiomycetes; and (4) amounts of deadwood and undergrowth were recorded on permanent sample plots established in 2010.
     In laboratories, woody samples were dried at a temperature of 60ºC for three days, their bulk density was determined; 102 samples were ground and analyzed for C, N and H content on an automatic CHNS analyzer; 67 samples were submitted for determination of Ca, P, K, Mg, Cu, Mn, Zn, Al, Cd and Pb by atomic absorption spectrometry (ICP-OES). Statistical analysis included the scatter plotting, descriptive statistics, preliminary regression, correlation analyses, and ANOVA.
     For the first time, we obtained woody bulk density and element contents for 7 species of broad-leaved forests (oak Quercus robur, ash Fraxinus excelsior, linden Tilia cordata, maple Acer platanoides, aspen Populus tremula, spruce Picea abies and birch Betula pendula) at five stages of woody decomposition and for elm (Ulmus glabra) at four stages. It was revealed that with an increase in the decomposition stage, the woody bulk density decreased on average from 0.467 g cm-3 at the zero stage to 0.050 g cm-3 at the fifth stage. The minimum losses were observed for Betula spp. and Picea abies, the maximum losses were observed for Acer platanoides. The carbon proportion practically did not differ between stages and between species; it averaged 45.4 ± 2.2%. The nitrogen proportion did not differ significantly between the species, but did differ between stages: it increased with increasing stage (on average, from 0.2 to 0.9 with a range of 0.1 to 1.7%). The interaction of species – decay stage was also significant: in the last stages, the highest nitrogen content was in linden, oak, and aspen samples, and the lowest in ash, elm, and spruce.
     For soil samples, physicochemical and microbiological characteristics were determined in laboratories; almost all characteristics varied greatly. The highest variation (up to 76%) of the largest number of variables (more than two-thirds of all considered) was explained by the species identity of the fallen logs. Our study showed for the first time that on a mass windthrow (14 years after the event), the soil characteristics as a whole significantly depend on the fallen tree species identity but the qualities of soil samples taken beyond and close to the deadwood do not differ much. This can be explained by the fact that within a mass windthrow, fallen trunks lie quite close to each other, and it is impossible to take samples further than 0.5 m from the trunk. Deadwood probably affects the soil at this distance.
     The inventory of dead wood and undergrowth showed that in 2020, the deadwood stock was 27.5% less than the stock recorded in 2010; the number of undergrowth also decreased by more than 2 times. The absolute dominance of aspen replaced by codominance of Norway maple, linden and aspen (2.7, 2.6 and 2.3 thousand individuals ha-1, respectively).
     Statistical processing of data collected in 2016 was performed and an article was submitted to the international journal about the overgrowth of fallen Quercus robur trunks with vascular plants in an area of an old-growth forest near the village Trud. For the first time it has been statistically shown that the presence of fallen logs significantly affects the total diversity and composition of vascular plant species in the forest tract. An increase in species richness is achieved through the successful establishment of boreal and light-demanding plant species on the logs.
     In the windthrow area, 73 species of basidiomycetes were identified. 36 fungal species were recorded for the first time in the Kaluga region. There were found extremely rare and little-known for the European part of Russia fungi, such as Hyphoderma incrustatum, Leucogyrophana sororia, Peniophorella clavigera, Phlebia subulata, Riopa metamorphosa, etc. A new locality of the rare (IUCN) species Subulicystidium perlong was identified.