Changes of Water Budget during Ecosystem Development in Post-Mining Sites at Various Spatiotemporal Scales: The Need for Controlled Systems

This chapter describes the development of the soil-water budget at various spatiotemporal scales, including an example of post-mining sites. This includes the formation of soil aggregates and porosity, the development of water retention in the soil profile, and water losses by runoff and evapotranspiration. It is emphasized that the development of soil-water retention is closely linked to carbon storage in post-mining soils, which is strongly affected by litter quality. Plants with a high C:N ratio of litter feature most of the organic matter in Oe and litter layers, which results in a lower soil-water storage, whereas soil covered by vegetation with low litter C:N ratios produces organo-mineral aggregates and deeper A horizons that promote water storage. Moreover, the need for controlled catchment conditions to get a better understanding of how these processes on various spatiotemporal scales interact is emphasized

Logging of rainforest and conversion to oil palm reduces bioturbator diversity but not levels of bioturbation

Anthropogenic habitat change is a major driver of species extinctions and altered species communities worldwide. These changes are particularly rapid in the tropics, where logging of rainforests and conversion to agricultural habitats is widespread. Because species have varying effects on their abiotic environment, we expect shifts in species composition to drive changes in ecosystem processes. One important ecosystem process is animal-driven bioturbation: the turnover of soil material by soil-dwelling organisms. We developed a protocol for measuring aboveground bioturbation, and assessed how bioturbation rates and standing amounts of aboveground bioturbated soil change as primary tropical rainforests are logged and converted to oil palm plantation. By identifying the animals that created soil structures, we assigned bioturbation activity to different soil-dwelling groups. Across all habitats, most standing bioturbated soil was generated by termites (97.0%), while short-term, small-scale bioturbation was mainly generated by earthworms (87.3%). The species diversity of social insects (ants and termites) involved in bioturbation was higher in primary forest than in either logged forest or oil palm plantation. However, neither standing bioturbated soil, nor short-term bioturbation rate differed among habitats. Unexpectedly, in primary forest, high levels of bioturbation were associated with low bioturbator diversity. This was because two termite species, where present, conducted nearly all bioturbation. There was no relationship between levels of bioturbation and diversity in the other habitats. Our results emphasize the importance, across all habitats, of termites for generating standing aboveground soil structures, and earthworms for short-term soil turnover. In oil palm plantation, bioturbation relies on a smaller number of species, raising concerns about future environmental change and consequent species loss

Tree species identity alters decomposition of understory litter and associated microbial communities : a case study

Investigations on how tree species modify decomposition of understory litter have rarely been conducted, although potentially having impacts on soil carbon stocks and stability. The aim of our study was to disentangle the effects different tree species (alder, spruce, oak, and willow) exert on litter decomposition by comparing decomposition patterns and microbial measures (phospholipid fatty acids and microbial DNA) of both tree and understory (Calamagrostis epigejos) litter exposed at the respective tree species stands of a common garden experiment. An initially uniform mass loss of understory litter exposed at the stands suggests that inherent litter quality (assessed by C:N ratios and lignin content) was the major driver in early decomposition. However, in later stages of our experiment, decomposition of understory litter began to differ among the stands, suggesting a delayed tree species effect. Here, differences in microbial community composition caused by tree species identity (e.g., through varying N supply or phenolics leached from low-quality litter) were likely the major determinants affecting the decomposition of understory litter. However, in these advanced decomposition stages, tree species identity only partly altered microbial communities associated with understory litter. These results indicate that the development of microbial communities on understory litter (and its decay) is likely a combined result of inherent chemical composition and tree species identity.Peer reviewe

The effect of underground drainage on peat meadows and inactivation of the drainage in an attempt to restore these meadows, which failed as it reduced the ability of soils to retain water

Drainage is often used to increase agriculture production, but it has adverse effects on biodiversity and water retention. Here, the effect of subsurface pipe drainage on peat meadows near Senotín (Czechia), which were drained from the mid-1980s to 1990s, was studied. Attempts were made to restore the peat meadows by damming drainage pipes using clay-filled trenches in 1996. In this case study, the effect on the depth of the water table, soil water retention, infiltration and soil temperature were recorded. Measurements of the original peat meadow (undrained site), drained meadow (drained site) and restored meadow (restored site) before restoration and two decades after restoration were recorded. The water table in undrained areas was higher than at drained and restored sites, indicating that drainage had lasting effect on drained and restored sites. Infiltration was lowest at the undrained site, greater at the drained site, and highest at the restored sites. Field water capacity was lowest at the restored site, greater at the drained site and highest at the undrained site. Soil water content at maximum saturation was lowest at the restored site, greater at the drained site and highest at the undrained site. Soil temperature was highest at the restored site with no significant difference between the undrained and drained sites. Soil moisture levels were highest at the undrained site and lowest at the drained site. In addition, the undrained and restored sites did not differ significantly in soil moisture content. In conclusion, restoration did not have a significant effect on the level of the water table, initiation of peat formation or ability of soil to hold water

Application of 13C NMR to investigate the transformations and biodegradation of organic materials by wood- and soil-feeding termites, and a coprophagous litter-dwelling dipteran larva

Solid-state 13C nuclear magnetic resonance spectroscopy has been used to characterize the C in samples of the food (wood), gut contents and faeces from the wood-feeding termite, Microcerotermes parvus; soil in the guts and mound material from the soil-feeding termite, Thoracotermes macrothorax; and the food and faeces from the litter-feeding, coprophagous larvae of the dipteran fly, Bibio marci. Spectra from the wood-feeding termite indicated preferential loss of polysaccharide and accumulation of lignin with some modification to the O-aromatic-C and methoxyl-C (O-methyl-C) components during passage through the gut. Spectra for the soil-feeding termite indicated little change in the distribution of 13C between resonances following passage through the gut, except for some evidence of preferential polysaccharide loss. Interpretation of the spectra from these organisms was restricted by the relatively low C content of the soils and mound material, and by the large contribution to the NMR spectra from the gut tissue rather than the gut contents. Spectra for the litter-feeding dipteran larvae indicated preferential feeding on the polysaccharide-rich component of the litter and then overall loss of polysaccharide-C and accumulation of both aromatic-C and methoxyl-C in the gut. These changes were greater for the second passage than for the first passage through the gut, suggesting that principally mechanical and physical changes occurred initially and that chemical digestion was prevalent during the second passage

Microbial communities in local and transplanted soils along a latitudinal gradient

Factors shaping community structure of soil microbiota have been intensively studied; however, the pattern in community composition and structure of soil microbiota at large geographical scales and factors regulating its metabolic activity remains poorly understood. Here, we used a field transplantation experiments to investigate the effects of substrate and climatic conditions on basal soil respiration, microbial biomass C and diversity of soil microbiota by comparing local and transplanted soils along a latitudinal gradient. Soil samples collected in April 2008 at donor site (Sokolov, Czech Republic) in Central Europe were gamma-ray sterilized and transplanted to receptor sites in Europe and the USA in May and early June 2008. Soil samples were taken in June 2009 after one year of exposure and immediately prepared for laboratory analysis. Basal soil respiration in local soils increased from 22 to 42 mg CO2-C kg-1 h-1 with latitude while basal soil respiration in transplanted soils decreased with latitude from 32 to 19 mg CO2-C kg-1 h-1. The microbial biomass C in both transplanted and local soils decreased with latitude. Content of fungal and bacterial phospholipid fatty acids increased nearly twice with latitude in local soils. Shannon diversity index of fungal community decreased from 2.5 to 1.2 along the latitudinal gradient in transplanted soils while local soils increased from 0.9 to 2.4 with latitude. Based on our results, microbial activity is driven mainly by changes of the soil substrate along latitudinal and climatic gradients while microbial biomass is driven more by global climatic factors itself. The diversity of soil microbial communities is mostly affected by latitudinal and climatic factors while community structure is mostly shaped by substrate quality