Humus horizon development during natural forest succession process in the Polish Carpathians

Abstract

As a result of socio-economic changes and land abandonment, the main ecological driver of the Carpathian landscape is the progression of the natural forest succession process. Thus, aspects of this process have become worthy of attention, especially in the context of carbon sequestration and the management of protected areas. Soil processes, especially within the topsoil, are some of the most susceptible to change, due to the accumulation of organic matter during such land-use transformations. The purposes of this study were to investigate the differences in topsoil development using the A Horizon Development Index (ADI) and to study the composition of humic substances and advanced organic matter humification in different land-use areas in selected Carpathian national parks, i.e. Bieszczady, Magura and Pieniny National Parks in southern Poland. Additionally, a goal of this study was to compare the ADI and the spectroscopic coefficients of humic substances as indicators of the degree of humus horizon shaping as well as advanced organic matter humification. In total, ten transects were selected, each consisting of three different land-use areas: semi-natural meadow, successional forest and old-growth forest. Soil colour was determined in fresh and air-dried samples using the Munsell colour chart. In air-dried soil samples pH, soil texture, total organic carbon and total nitrogen were measured. Humic substances were extracted and further characterized by UV-VIS spectroscopy. The ADI confirmed the influence of natural forest succession on soil colour darkening and the development of the uppermost soil layer. Spectroscopic analyses of humic substances showed two different patterns depending on soil depth. In the 0–10 cm layer, natural forest succession reduced the rate of the humification process and decreased the degree of maturity of fulvic acids; in the 10–20 cm layer, it led to an increase in the rate of the humification process and a decrease in the content of humic and fulvic acids at the beginning of the transformation. The comparison of two different indicators of soil development–the ADI and the spectroscopic coefficients of humic substances (Q4/6, Q2/4, Q2/3, δ log K) — indicated that these indexes are based on different features of soil and cannot be used interchangeably.

Urban Grassland Afforestation as a Public Land Management Tool for Environmental Improvement: The Example of Krakow (Poland)

“…This suggests that SOM stabilisation, which can be surprising and not coordinated with other SOM parameters, such as the C/N and HA/FA ratios and amounts of Hus, was significantly lower in the CGF than the CGM soil. This shows that the ADI relates more to C storage than SOM stabilisation [42], as proven in this study by a regression equation (ADI = 0.6666 + 0.1903C, r = 0.6223 at p = 0.00001), which indicated a positive relationship between the C content and the ADI value in the studied soils (Figure 3). The effect of plant cover on C storage and SOM stabilisation was highlighted by the results of the PCA.…”

Changes in humus content on the territory of agricultural lands in the Issyk-Kul basin of Kyrgyzstan

“…The chestnut and light-brown soils are different in morphology, clay fraction chemistry, mineralogy and are supposed to be very different in content, distribution, and composition of soil organic matter [9]. The high humus content in black-brown soils is attributed to the continuous organic matter input from the forest litter or grasses [6,7]. There are also evidences in the literature that the loss of humus in the depths of arable horizon in the Issyk-Kul region of Kyrgyzstan from 1972 to 2000 ranged from 19 to 57%, depending on the degree of erosion [5].…”

“…Soil fertility depends on the humus content and mineral substances in the arable layer. The loss of humus in the upper layers of soils is related to continuous decrease of input of fresh organic matter on the soil surfaces as well as lower microbial activity in the top layer of soil, which are the main factors affecting humification [6]. The decrease of microbial activity in the upper layers could be related to over-use of chemical fertilizers that is very common in Kyrgyzstan.…”