Marina Nadporozhskaya

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.

Analysis of the dynamics of plant residue mineralization and humification in soil

The quantitative aspects of mineralization and humification of organic residues in soil were analyzed on the basis of the experimental curves of their transformation and using three conceptual approaches. Ågren’s and Bosatta’s concept of the continuum of substrate quality loss accentuates the gradual reduction of the availability of the decomposable material for microorganisms. The discrete succession concept emphasizes the existence of morphologically and biochemically distinguishable stages (a fraction cascade) of transforming the organic debris into humus. According to the biochemical concept, the organic debris transformation is represented as the mineralization of individual organic substances with different rates, more often without taking into account the influence of humus formation. The testing of these concepts led to the conclusion that the discrete succession and biochemical concepts should be integrated for the elaboration of the theoretical basis for assessing the rate of organic debris transformation in the soil.

Properties of soil organic matter of Plaggic Anthrosols from Northwest Germany, Northwest and North Russia

The study focuses on the properties of soil organic matter (SOM) of Plaggic Anthrosols from Northwest Germany, Northwest Russia and North Russia. As the sites differ in type of plaggen material and manner and duration of plaggen management, the aim was to find out whether these differences influence SOM. The studied soils show different SOM qualities by the C/N ratios of TOC, by the C/N ratios in the particle size fractions and IR spectra, the latter indicating the occurrence of keto- and carboxyl groups only for the German soil and amides exclusively for the Russian ones. The HCl-resistant organic carbon (OC) and the H2O2-resistant OC was largest and the HF-soluble OC was lowest in the Northwest Russian soil. With decreasing amounts in the sequence Northwest Germany, North Russia and Northwest Russia, the highest OC content was found in the fine silt and clay fractions. With the exception of the HF-soluble OC the parameters stay constant with depths of the plaggic epipedons, indicating no alteration with time. C/N ratios of TOC and different fractions as well as IR-spectra show distinct differences in the properties of SOM, reflecting different kinds of plaggen material and differences within the plaggen fertilization system.

Simulation study of nitrogen supply in boreal forests using model of soil organic matter dynamics ROMUL

A set of model simulations was performed to quantify the effects of environmental factors and soil properties on available nitrogen pool and dynamics in European boreal forests. The results of simulation of the effect of soil temperature and moisture show a maximum of available nitrogen in times of optimal soil temperature and moisture. The increasing of nitrogen and ash content in forest litter has also positive influence on a production of available nitrogen in forest soils. If a soil has a well-developed surface organic horizon (forest floor in Moder and Raw humus), then the majority of available nitrogen is produced in the organic layer. The results of this simulation supports the important role played by forest floor in the soil nutrition of boreal forest ecosystems.

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.

Chemical sensors for soil analysis: principles and applications

Chemical sensors promise low-cost and easy-to-handle analytical devices for environmental monitoring and soil analysis in particular. In this chapter, the principles and selected applications of chemical sensors and multisensory systems for the assessment of soils and main soil nutrition component detection performed over the past two decades are overviewed. The main benefits and drawbacks of chemical sensors employment in soil analysis are highlighted and discussed.

Xylem sap mineral analyses as a rapid method for estimation plant-availability of Fe, Zn and Mn in carbonate soils: a case study in cucumber

Low plant-availability of iron (Fe), zinc (Zn) and manganese (Mn) leads to micronutrient deficiency, causing significant yield reductions of crops throughout the world, especially in calcareous soils. This study was performed in order to evaluate the efficiency of xylem sap analysis in the determination of Fe, Zn and Mn availability in plants (Cucumis sativus L.) affected by calcium carbonate (CaCO3) levels. A soil with six levels of CaCO3 (0−10% DW) was used. We performed a combination approach, including analysis of the soil mobility of micronutrients using different extractants (water, DTPA-TEA and ammonium acetate), as well as xylem and shoot elemental analysis. Generally, application of CaCO3 resulted in a pH increase of the bulk soil of 1.4−2.2 pH units; extractability of all micronutrients was significantly decreased 1.4−4.2 times, irrespective of the extracting solution. Xylem sap Fe, Zn and Mn concentrations were significantly correlated with the respective concentrations in the soil extracting solutions. By contrast, only shoot concentrations of Zn and Mn, but not of Fe, were linearly correlated with their extractable forms. With electrothermal atomic absorption spectrometry, changes in xylem sap concentrations of micronutrients were detected without preliminary mineralization of plant material, in contrast to shoot analysis. Our results demonstrate that xylem sap analysis offers the advantages of a simple characterization of multi-microelement availability in plants under CaCO3 stress.