Sergey Bykhovets

ROMUL — a model of forest soil organic matter dynamics as a substantial tool for forest ecosystem modeling

This paper discusses a model of forest soil organic matter based on the concept of succession stages of soil organic matter decomposition marked by different groups of soil fauna inherent to forest soils in contrast to well-mixed agricultural soils with microbiology kinetics. This model allows the calculation of the dynamics of soil organic matter and the corresponding dynamics of nitrogen, including the evaluation of the amount of mineral nitrogen which is available for plants. The input parameters are the amount and quality of litter input, climatic data and initial amounts of soil organic matter and corresponding nitrogen. The litter may be split into different cohorts which are characterised by different ash and nitrogen contents and location on/in a soil as above-ground and below-ground litter cohorts. A specially developed simulator of soil climate is also described. A comparison was made with a previous, more restricted version of this model. The origin of the differences is discussed in detail. Examples of simulation scenarios show a wide range of possible applications for the model as a separate unit of models for forest ecosystems dynamics.

EFIMOD 2: a model of growth and cycling of elements in boreal forest ecosystems

Abstract The model EFIMOD 2 was developed for the description of tree (stand) growth and biological turnover of elements in boreal and temperate forest ecosystems. The model has the following features. (i) It is a spatially explicit stand-level simulator for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L. Karst) and Pendula birch (Betula pendula L.) on different forest soils growing under different climatic conditions in Europe; each stand consists of individual trees for which growth is modelled depending on the tree’s position within the stand and local light, water and available nutrient conditions. (ii) The model has a tree-based submodel for total biomass distributed between several biomass compartments. (iii) The calculations include natural regeneration as well as ground vegetation dynamics. (iv) The soil submodel (ROMUL) is used to assess organic matter dynamics and nitrogen availability for tree growth as a function of soil temperature, soil moisture content and litter quality. (v) EFIMOD 2 calculates nitrogen cycling and accounts for atmospheric nitrogen deposition, nitrogen fixation and leaching, vegetation uptake, litter fall and nitrogen redistribution within and between trees and soil horizons. (vi) Monte–Carlo simulations are done to simulate the extent of naturally oscillating variability. EFIMOD 2 allows for short-term and long-term simulations of natural and managed forest ecosystem dynamics over a wide range of forest sites, climatic conditions and silvicultural regimes. The model calculates dendrometric parameters for every tree, including undergrowth and seedlings, total growing stock, and pools of coarse woody debris and soil organic matter, with special reference to carbon and nitrogen dynamics. The model is effective for assessing wood productivity and evaluation of forest management regimes to meet criteria and indicators of Sustainable Forest Management. This includes a general evaluation of biodiversity and soil sustainability. The model system allows for the direct use of standard forest inventory data. Output variables include carbon and nitrogen pools in the stand and soil, CO2 emissions, and tree (stand) growth and yield.

Application of the forest ecosystem model EFIMOD 2 to jack pine along the Boreal Forest Transect Case Study

Sustainability of forest ecosystems and climate change are two critical issues for boreal forest ecosystems in Canada that require an understanding of the links and balance between productivity, soil processes and their interaction with natural and anth ropogenic disturbances. Forest ecosystem models can be used to understand and predict boreal forest ecosystem dynamics. EFIMOD 2 is an individual tree model of the forest-soil ecosystem capable of modelling nitrogen feedback to productivity in response to changes in soil moisture and temperature. It has been successfully applied in Europe, but has not been calibrated for any forest ecosystem in Canada. The objective of this study was to parameterize and validate EFIMOD 2 for jack pine in Canada. Simulated and measured results agreed for changes in tree biomass carbon and soil carbon and nitrogen with increasing stand age and across a climatic gradient from the southern to northern limits of the boreal forest. Preliminary results from scenario testing indic...

Identification of Labile and Stable Pools of Organic Matter in an Agrogray Soil

The intensity of decomposition of the organic matter in the particle-size fractions from a agrogray soil sampled in a 5-year-long field experiment on the decomposition of corn residues was determined in the course of incubation for a year. The corn residues were placed into the soil in amounts equivalent to the amounts of plant litter in the agrocenosis and in the meadow ecosystem. A combination of three methods—the particle-size fractionation, the method of 13C natural abundance by C3–C4 transition, and the method of incubation—made it possible to subdivide the soil organic matter into the labile and stable pools. The labile pool reached 32% in the soil of the agrocenosis and 42% in the meadow soil. Owing to the negative priming effect, the addition of C4 (young) carbon favored the stabilization of the C3 (old) carbon in the soil. When the young carbon was absent, destabilization or intense decomposition of the old organic matter was observed. This process was found even in the most stable fine silt and clay fractions.

Effect of temperature on the decomposition rate of labile and stable organic matter in an agrochernozem

An hypothesis about the different temperature dependences of the decomposition of the labile and stable organic carbon pools has been tested using an agrochernozem sampled from an experimental plot of 42-year-old continuous corn in Voronezh oblast. The partitioning of the CO2 loss during the decomposition of the labile and stable soil organic matter (SOM) at 2, 12, and 22°C in a long-term incubation experiment was performed using the method of 13C natural abundance by C3–C4 transition. On the basis of the determined decomposition constants, the SOM pools have been arranged in an order according to their increasing stability: plant residues < new (C4) SOM < old (C3) SOM. The tested hypothesis has been found valid only for a limited temperature interval. The temperature coefficient Q10 increases in the stability order from 1.2 to 4.3 in the interval of 12–22°C. At low temperatures (2–12°C), the values of Q10 insignificantly vary among the SOM pools and lie in the range of 2.2–2.8. Along with the decomposition constants of the SOM, the new-to-old carbon ratio in the CO2 efflux from the soil and the magnitude of the negative priming effect for the old SOM caused by the input of new organic matter depend on the temperature. In the soil under continuous corn fertilized with NPK, the increased decomposition of C3 SOM is observed compared to the unfertilized control; the temperature dependences of the SOM decomposition are similar in both agrochernozem treatments.

Analysis of the soil organic matter stability in spruce forests of Krkonose in Czechia on the basis of the ROMUL mathematical model

Computational experiments with the ROMUL mathematical model were performed for studying the dynamics of soil organic matter (SOM) in spruce forests of northeastern Czechia that were disturbed because of the atmospheric sulfur deposition in the second half of the 20th century. The effect of the soil acidification on the decomposition dynamics of the forest die-back in the model is of importance. Conditions of the forest productivity were found under which the SOM pool could be preserved. It was shown that, later on, the content of the litter will decrease because of the forest degradation, and the succession changes due to the effect of the contamination will affect the type of vegetation, as well as the type of soil organic matter. The total SOM content will decrease in this case. However, the maintenance of the grass productivity can slow down this process. It was noted that the quantitative prediction of the SOM dynamics requires measurements of the productivity parameters of the forest as a whole and the living ground cover, including the content of root litter, and the hydrothermal regime of the soil determining the transformation of the litter and humus.

Model Predictions of Effects of Different Climate Change Scenarios on Species Diversity with or without Management Intervention, Repeated Thinning, for a Site in Central European Russia

The EFIMOD-ROMUL soil-vegetation dynamic model of carbon and nitrogen cycles in forest ecosystems and a static ground vegetation model BioCalc were used for simulating the dynamics of forest ecosystem parameters and prognosis of plant species biodiversity under two management and two climate change scenarios. A large forested area occupying approximately 1,800 km2 on the Central Russian Plain (in Kostroma administrative region) was taken as a case study. Natural forest development (forest reservation) and clear cutting regime were taken as the management scenarios. The most dramatic climate change based on HadCM3 model and A1Fi emission scenario and ‘stationary climate’ were taken as the climatic scenarios. The simulation results showed that clear cutting impacts on forest biodiversity are very strong in the study area and climate warming has minimal effect on biodiversity under the clear cutting regime but climate changes lead to a slight decrease in species diversity under the forest natural development.

CLIMATE OF MOSCOW REGION SOUTH: CURRENT TRENDS AND ASSESSMENT OF THE ANOMALITY

Резюме. Изменения климата, наблюдаемые в настоящее время на значительной части территории России, проявляются как в повышении температуры воздуха, так и в увеличении числа погодных аномалий, усиливающих общую аномальность климата. На основе долговременных рядов метеорологических наблюдений, проводимых на Станции фонового мониторинга в Приокско-Террасном Государственном биосферном заповеднике с 1973 года, охарактеризованы современные тренды основных метеорологических параметров. Выполнена оценка аномальности климата в районе южного Подмосковья. Показано, что наиболее заметными тенденциями современного климата в южном Подмосковье наряду с однонаправленным увеличением среднегодовой и среднесезонных температур воздуха являются усиление засушливости летнего периода и потепление зимнего сезона. Последнее проявляется в уменьшении продолжительности и максимальной высоты снежного покрова. Расчеты показали, что после 1994 г. происходит смена знака суммы аномалий с отрицательного на положительный как для среднегодовых и среднесезонных температур, так и для суммарного количества осадков. За 44-летний период метеонаблюдений нам не удалось выявить однозначной тенденции увеличения повторяемости аномальных погодных явлений по всем анализируемым показателям. Однако в 2006-2016 гг. проявился отчетливый рост числа аномальных лет как по величине летнего гидротермического коэффициента Селянинова, так и по сумме осадков во все календарные сезоны года, кроме зимнего. Ключевые слова. Изменение регионального климата, гидротермический коэффициент Селянинова, аридизация, аномалии, засухи, южное Подмосковье.

Effect of temperature and moisture on the mineralization and humification of leaf litter in a model incubation experiment

The mineralization and humification of leaf litter collected in a mixed forest of the Prioksko-Terrasny Reserve depending on temperature (2, 12, and 22°C) and moisture (15, 30, 70, 100, and 150% of water holding capacity ( WHC)) has been studied in long-term incubation experiments. Mineralization is the most sensitive to temperature changes at the early stage of decomposition; the Q10 value at the beginning of the experiment (1.5–2.7) is higher than at the later decomposition stages (0.3–1.3). Carbon losses usually exceed nitrogen losses during decomposition. Intensive nitrogen losses are observed only at the high temperature and moisture of litter (22°C and 100% WHC). Humification determined from the accumulation of humic substances in the end of incubation decreases from 34 to 9% with increasing moisture and temperature. The degree of humification CHA/CFA is maximum (1.14) at 12°C and 15% WHC; therefore, these temperature and moisture conditions are considered optimal for humification. Humification calculated from the limit value of litter mineralization is almost independent of temperature, but it significantly decreases from 70 to 3% with increasing moisture. A possible reason for the difference between the humification values measured by two methods is the conservation of a significant part of hemicelluloses, cellulose, and lignin during the transformation of litter and the formation of a complex of humic substances with plant residues, where HSs fulfill a protectoral role and decrease the decomposition rate of plant biopolymers.

Thermal Impact of Gas Flares on the Biological Activity of Soils

Global warming can lead to a significant transformation of the structure of terrestrial ecosystems and changes in the mode of functioning of their components. In this connection, studies of soil respiration, particularly of the biological activity of soils under forest exposed to warm impact of flaring flare are of scientific and practical interests. A long-term experimental plot was established in a lichen pine forest on the Albic Podzols (Arenic) (Khanty-Mansi Autonomous Area-Yugra). Sampling and measurements were carried out in the areas at the distances of 70, 90, and 130 m from the flare with the strong, moderate, and weak heating effects, respectively. In the zone of the maximum heating effect, the soil temperature was by 1.3°C higher, and the rate of CO2 emission from the surface in situ was greater by 18% compared to the zone with weak impact of the flare. Along with increasing CO2 emissions, organic matter accumulated due to increasing the stable pool. The parameters of the microbial biomass, basal respiration, and the input of labile organic matter pool increased with the distance from the flare.