Csaba Centeri

Redistribution of Soil Organic Carbon Triggered by Erosion at Field Scale Under Subhumid Climate, Hungary

Abstract Soil organic carbon (SOC) has primary importance in terms of soil physics, soil fertility and even of climate change control. One hundred soil samples were taken from an intensively cultivated Cambisol to quantify SOC redistribution triggered by soil erosion under a subhumid climate, by the simultaneous application of diffuse reflectance (240–1 900 nm) and traditional physico-chemical methods. The representative sample points were collected from the solum along the slopes at the depth of 20–300 cm with a mean SOC content of 12 g kg−1. Hierarchical cluster analyses were performed based on the determined SOC results. The spatial pattern of the groups created were similar, and even though the classifications were not the same, diffuse reflectance had proven to be a suitable method for soil/sediment classification even within a given arable field. Both organic and inorganic carbon distributions were found to be a proper tool for estimations of past soil erosion processes. The SOC enrichment was found on two sedimentary spots with different geomorphological positions. Soil organic matter composition also differed between the two spots due to selective deposition of the delivered organic matter. The components with low-molecular-weight reached the bottom of the slope where they could leach into the profile, while the more polymerised organic matter compositions were delivered and deposited even before on a higher segment of the slope in an aggregated form. This spatial difference appeared below the uppermost tilled soil layer as well, referring the lower efficiency of conventional ploughing tillage in soil spatial homogenisation.

Parallels of secondary grassland succession and soil regeneration in a chronosequence of central-Hungarian old fields

This study deals with spontaneous regeneration of fen and steppe meadows and corresponding soil properties on extensively managed ex-arable fields. Our first main aim was to analyse the nature of relations between various vegetation and soil parameters and time since abandonment and to determine the time needed for regeneration. Our second major goal was to determine the main environmental factors influencing regeneration success. Time since abandonment of the studied areas was determined with military maps, aerial photographs and the help of local rangers. Stands which were presumably not ploughed for over 150 years were taken as a reference. Vegetation surveys and soil sampling were carried out in 307 plots with different soil moisture conditions. The correlation with time was tested for relevant vegetation and soil parameters. The influence of different parameters on the species composition was tested with a generalized linear mixed model. We found that vegetation and soil parameters approach the level of long-term (permanent) grassland in a similar asymptotic curve. Numerous characteristic target vegetation species and legally protected species have colonized the old fields. The time frame needed for regeneration can be stated to be 20–40 years for the majority of sites, but the proportion of favourable species in the resulting grasslands is divergent. The most important finding among soil properties was a pronounced negative effect of plant available phosphorus on the species composition of regenerating grassland. We conclude that relying on spontaneous recolonization for grassland restoration in central Hungary is promising, particularly on sites which were not fertilized intensively with phosphorus prior to abandonment.

Comparison of erosion, soil and vegetation relation of extensive pannonian meadows under Mediterranean and Submediterranean effects

Introduction The Mediterranean effects prevail in the Pannon biogeographical region, thus in Hungary, too. It was described in the southern part of Hungary and in the Trans-Danubian areas. The effected areas are mainly meadows or sparse forests mixed with bushes. These were the typical vegetation types of the area in its natural state. The other important characteristics of these areas are shallow soil depth, extreme low soil water content in summer and southern exposure. The typical agricultural activity is grazing that reflects the ecological background of the area. Overgrazing has extremely negative effects on these very sensitive soils. There are other human effects: military activity, trampling and vegetation burning etc. From our researches on the Trans-Danubian region we present the results from Soly (Penksza et al. 1998, Sule et al. 2005).