Search Results - (Author, Cooperation:S. Scheu)

2014-05-09

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Arctic Regions ; *Biodiversity ; Carbon/metabolism ; *Carbon Cycle ; *Ecosystem ; Nitrogen/metabolism ; Nitrogen Cycle ; Plants/metabolism ; Tropical Climate

0929-1393

Aspen forest ; Bacterial/fungal ratio ; Carbon mineralization ; Dendrobaena octaedra ; Microbial biomass ; Nutrient cycling ; Pine forest

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Electronic Resource

0038-0717

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Electronic Resource

0038-0717

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Electronic Resource

1432-0789

Earthworm casts ; Microbial respiration ; Microbial biomass ; Nitrogen ; Phosphorus ; Aporrectodea caliginosa

Springer Online Journal Archives 1860-2000

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Summary Microbial respiration, microbial biomass and nutrient requirements of the microflora (C, N, P) were studied in the food substrate (soil taken from the upper 3 cm of the mineral soil of a beech wood on limestone), the burrow walls and the casts of the earthworm Aporrectodea caliginosa (Savigny). The passage of the soil through the gut caused an increase in soil microbial respiration of about 90% over a 4-week period. Microbial biomass was increased only in freshly deposited casts and decreased in aging faeces to a level about 10% lower than in soil. Microbial respiration of the burrow walls was only increased over a shorter period (about 2 weeks). The microflora of the soil and the burrow walls was limited by P, whereas in earthworm casts, microbial growth was limited by the amount of available C. In aging faeces the P requirement of the microflora increased and approached that of the soil. Immobilization of phosphate in earthworm casts is probably caused by mainly abiotic processes. C mineralization by soil microflora fertilized with glucose and P was limited by N, except in freshly deposited casts. Ammonium, not nitrate, was responsible for this process. N dynamics in earthworm casts are discussed.

Electronic Resource

1432-0789

Litter decomposition ; Succession ; Microbial biomass ; Microbial respioration ; Microbial nutrient status

Springer Online Journal Archives 1860-2000

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract Microbial biomass, microbial respiration, metabolic quotient (qCO2), Cmic/Corg ratio and nutrient status of the microflora was investigated in different layers of an aspen (Populus tremuloides Michx.) and pine forest (Pinus contorta Loud.) in southwest Alberta, Canada. Changes in these parameters with soil depth were assumed to reflect successional changes in aging litter materials. The microbial nutrient status was investigated by analysing the respiratory response of glucose and nutrient (N and P) supplemented microorganisms. A strong decline in qCO2 with soil depth indicated a more efficient C use by microorganisms in later stages of decay in both forests. Cmic/Corg ratio also declined in the aspen forest with soil depth but in the pine forest it was at a maximum in the mineral soil layer. Microbial nutrient status in aspen leaf litter and pine needle litter indicated N limitation or high N demand, but changes in microbial nutrient status with soil depth differed strongly between both forests. In the aspen forest N deficiency appeared to decline in later stages of decay whereas P deficiency increased. In contrast, in the pine forest microbial growth was restricted mainly by N availability in each of the layers. Analysis of the respiratory response of CNP-supplemented microorganisms indicated that growth ability of microorganisms is related to the fungal-bacterial ratio.

Electronic Resource

1432-0789

Key wordsFagus sylvatica ; Urtica dioica ; Nitrate leaching ; Forest ; Lumbricidae ; Decomposition ; Mineralization ; Octolasion lacteum ; Litter ; CO2 production

Springer Online Journal Archives 1860-2000

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract Effects of leaf litter of beech (Fagus sylvatica L.) and stinging nettles (Urtica dioica L.) and of the endogeic earthworm species Octolasion lacteum (Örley) on carbon turnover and nutrient dynamics in soil of three beechwood sites on a basalt hill (Hesse, Germany) were investigated in a laboratory experiment lasting for about 1 year. The sites were located along a gradient from basalt (upper part of the hill) to limestone (lower part of the hill) with an intermediate site in between (transition zone). At the intermediate site U. dioica dominated in the understory whereas at the other sites Mercurialis perennis L. was most abundant. The amount and composition of organic matter was similar in soil of the basalt (carbon content 5.9%, C/N ratio 13.8) and intermediate site (carbon content 5.6%, C/N ratio 14.3) but the soil of the intermediate site produced more CO2 (in total +17.5%) and more nitrogen (as nitrate) was leached from this soil (in total +55.6%). It is concluded that the soil of the intermediate site contains a large mobile carbon and nitrogen pool and the formation of this pool is ascribed to the input of U. dioica litter. Leaf litter of U. dioica strongly increased NO3 –-N leaching immediately after the litter had been added, whereas nitrogen was immobilized due to addition of beech litter. Despite the very fast initial decomposition of nettle litter, the increase in CO2 production due to this litter material was only equivalent to 20.1% of the amount of carbon added with the nettle litter; the respective value for beech litter was 34.8%. Earthworms altered the time course of carbon and nitrogen mineralization in each of the treatments. In general, earthworms strongly increased mineralization of nitrogen but this effect was less pronounced in soil of the intermediate site (treatments without litter), which is ascribed to a depleted physically protected nitrogen and carbon pool. In contrast, their effect on the total amount of nitrogen mobilized from nettle litter was small. Earthworms significantly reduced CO2 production from soil of the intermediate site (treatments without litter) and it is concluded that earthworm activity contributes to the restoration of the depleted physically protected carbon pool at this site.

Electronic Resource

1432-1939

Key words Soil fauna ; Trophic structure ; Detritivores ; Predators ; 15N

Springer Online Journal Archives 1860-2000

Biology

Abstract  The structure of the soil food web in two beech (Fagus sylvatica) forests, the Göttinger Wald and the Solling forest (Northern Germany), was investigated using variations in tissue 15N concentrations of animal species or taxa. The Göttinger Wald is located on a limestone plateau and characterized by mull humus with high macrofauna activity, particularly of Lumbricidae, Diplopoda and Isopoda. In contrast, the Solling forest is located on a sandstone mountain range and characterized by moder humus. The soil fauna of this forest is dominated by mesofauna, particularly by Collembola, Enchytraeidae and Oribatida. In June 1995 soil fauna was sampled using heat extraction. Three soil layers were analysed at each of the sites. 15N/14N ratios of bulk material increased strongly with soil depth in both forests. This also applied to the water-soluble fraction at the Göttinger Wald, but not at the Solling. Generally, the water-soluble fraction was more enriched in 15N than the bulk materials. For most animals studied 15N/14N ratios varied little with soil depth. In both forests soil animals could be classified either as saprophages, including microphytophages, or predators. On average, the δ15N of predatory taxa (Chilopoda, Araneida, Gamasina, Staphylinidae) exceeded that of saprophagous or microphytophagous taxa (Lumbricidae, Isopoda, Diplopoda, Collembola, Oribatida, Enchytraeidae) by 4.4 and 3.9‰ for the Göttinger Wald and the Solling, respectively. We assume that most of the saprophagous or microphytophagous taxa studied consist of primary and secondary decomposers and hypothesize that predators prey more on secondary than primary decomposers. Generally, average δ15N values differed little between saprophagous (Lumbricidae, Diplopoda, Isopoda) and microphytophagous taxa (Collembola, Oribatida). The variations in δ15N values of species within these taxa consistently exceeded the variation between them, indicating that the species of each of these taxa form a continuum from primary to secondary decomposers. Also, variations in δ15N values within predatory taxa in most cases exceeded that between taxa excluding top predators like Sorex. We conclude that using higher taxonomic units in soil food web analysis is problematic and in general not consistent with nature. Higher taxonomic units may only be useful for depicting very general trophic groupings such as predators or microbi-detritivores.

Electronic Resource

1432-1939

Earthworms ; Nitrogen dynamics ; Nitrogen net mineralization ; Beech wood ; Field calculation

Springer Online Journal Archives 1860-2000

Biology

Summary The influence of earthworms (Aporrectodea caliginosa (Savigny) and Lumbricus castaneus (Savigny)) on the rate of nitrogen net mineralization of the soil was studied in the laboratory and in the field. The additional mineralization of nitrogen cause by the burrowing activity of the substrat feeding earthworm A. caliginosa (N L )was directly correlated to the biomass of the lumbricids independently of their number. A rise in temperature caused an exponential increase in N L values. The Q 10 value of this process (2.18) was found to be much higher than that of the nitrogen mineralization without earthworms (Q 10=1.22). At 15°C the N L value caused by A. caliginosa was calculated to be about 250 μg N g-1 fresh body wt d-1. Using the experimentally determined exponential relationship between temperature and N L values, the additional nitrogen mineralization caused by a population of A. caliginosa in a beechwood on limestone was calculated to be 4.23 kg ha-1 a-1. In contrast to A. caliginosa the litter dwelling species L. castaneus lost considerable amounts of biomass (56%) during the 4 week incubation period. Only 1/3 of the nitrogen equivalent to the weight loss of the animals was recovered in the mineral nitrogen pool. The addition of litter (old beech leaf litter, freshly fallen beech and ash leaf litter) had a pronounced effect on both nitrogen net mineralization and N L values of the soil. Presence of old beech leaves caused an increase in both values, wheres the other litter types effected a decrease in nitrogen net mineralization. Fragmented ash litter was found to have the most distinct effect on N L values (-69%) and nitrogen net mineralization (-74%).

Electronic Resource

1432-1939

Microbial nutrient status ; Microbial nutrient limitation ; Microbial biomass ; Secondary succession ; Earthworms

Springer Online Journal Archives 1860-2000

Biology

Summary Microbial biomass, nutrient (N and P) status, and carbon and nutrient limitation of the microflora were investigated in soils from five different sites (field, 5-, 12-, and about 50-year-old fallow, beechwood), which represent different stages of a secondary succession from a wheat field to the climax ecosystem of a beechwood on limestone. In addition, the effect of faeces production by the substrate feeding earthworm species Octolasion lacteum (Örley) on the nutrient status of the soil microflora of these sites was studied. Humus had accumulated in the soil of the third fallow site, with an enhanced biomass of microflora. However, in the beechwood soil, which had the highest humus content, microbial biomass was lower than in the soil of the third fallow site and similar to that of the field and the two younger fallow sites. In general, soil microbial biomass was little affected by the passage of soil through the gut of O. lacteum. The soil microflora of the field, the 5-, 12-, and about 50-year-old fallow was limited by carbon, whereas in the beechwood soil phosphorus limited microbial growth. NItrogen availability to the soil microflora was low in the two younger fallow sites and high in the field and the third fallow. In the beechwood soil nitrogen supply did not affect microbial carbon utilization. Application of phosphorus stimulated glucose mineralization in the soil of the field, the third fallow, and the beechwood, but not in the two younger fallow sites. Therefor, the nutrient status of the soil microflora seems to have changed during secondary succession: presumably, during the first phase the availability of nitrogen decreased, whereas during the second phase microbial phosphorus supply became more important, which resulted in phosphorus limitation of the soil microflora in the climax ecosystem. The passage of soil through the gut of O. lacteum caused an alteration in the microbial nutrient status. Generally, microbial growth in earthworm casts was limited by carbon. The relative effect of the gut passage of the soils on microbial carbon utilization seems to increase during succession. Therefore, the effect of decomposer invertebrates on microbial nutrient supply seems to increase during secondary succession. In general, nitrogen did not limit microbial carbon utilization in earthworm casts. Phosphorus requirements of the soil microflora were lowered by the gut passage of the soil of the third fallow site and the beechwood, which indicates an increased phosphorus supply in earthworm casts. Howerver, this additional supply was not sufficient to enable optimal carbon utilization by the soil microflora. The results indicate that the effect of decomposer invertebrates on the soil microflora depends on the nutrient status of the ecosystem.

Electronic Resource

1432-1939

Earthworms ; burrowing activity ; Bioturbation ; Beech wood ; Field calculation

Springer Online Journal Archives 1860-2000

Biology

Summary Burrow formation (burrow length and faeces production) of the substrate feeding earthworm Aporrectodea caliginosa (Savigny) in relation to three temperatures (5, 10 and 15°C) and soil moisture contents (48, 60 and 73% water of dry wt) was determined. Soil moisture content affected the burrowing activity of A. caliginosa only below a distinct threshold (60% water of dry wt). At sufficient moisture an, increase in temperature by 5° C approximately doubled the amount of egesta produced. Another substrate feeding earthworm (Octolasion lacteum (Örley)) showed a similar pattern of burrowing activity. The data for the dependence of the faeces production of A. caliginosa on soil temperature and moisture content were combined with field data. The amount of faeces produced by the population of this earthworm species in a beechwood on limestone was calculated to be about 4.23 kg ha-1 a-1. The amount of egesta produced by all substrate feeding species is assumed to exceed 6 kg ha-1 a-1, which is equivalent to a soil layer of approximately 9 mm. This group of earthworms is therefore considered to be of greater importance for bioturbation and the formation of mull than previously assumed.

Electronic Resource

1432-0789

Acid rain ; Soil fauna ; Litter decomposition ; Litter fragmentation ; Bioturbation

Springer Online Journal Archives 1860-2000

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Summary The effect of simulated acid rain on the decomposition of C-14-labelled beech leaf litter (4 months old), and the modification of this effect by litter fragmentation by the millipede Glomeris marginata (Villers) and by the burrowing activity of two earthworm species [Lumbricus castaneus (Savigny) and Octolasion lacteum (Örley)], was studied in laboratory experiments over a period of 168 days. The acid rain caused a strong decrease in C mineralization of intact beech leaf litter situated on the surface of the carbonate-rich mineral soil (to 0.43 of control), whereas CO2 production by the systems was increased (up to 1.12 times the control level). In general, the activity of the decomposer macrofauna buffered the effects of the acidity. Litter fragmentation by G. marginata reduced the effect of acid precipitation on litter decomposition by almost 50%. The burrowing activity of L. castaneus and O. lacteum led to contact between the intact leaf litter and the mineral soil, which buffered the effect of the acid precipitation on litter decomposition by 82% and 65%, respectively. The epigeic earthworm species L. castaneus, by feeding on and removing the faecal pellets of G. marginata from the soil surface, almost totally buffered the effect of the acid rain on pellet decomposition. The activity of the endogeic earthworm species O. lacteum in feeding on Glomeris faecal pellets and mixing them with mineral soil also buffered the effect of the acid rain. However, this effect appeared to be restricted to the first 5 weeks. In total, by mixing fragmented litter with mineral soil, O. lacteum stabilized organic matter in the mineral soil horizon. This stabilization effect was assumed to be independent of the simulated acid precipitation. In addition, the activity of O. lacteum compensated for the increased CO2 production induced by the acid rain. An intact soil faunal community is therefore considered to be a key component in the buffering characteristic of beechwood mull soils.

Electronic Resource

1432-0789

Endogeic earthworms ; Lumbricidae ; Mucus excretion ; C turnover ; Octolasion lacteum ; Aporrectodea caliginosa

Springer Online Journal Archives 1860-2000

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Summary Mucus excretion of endogeic earthworms, by the body surface to burrow walls and by the intestine to casts, was investigated using uniformly 14C-labelled adult or subadult specimens of Octolasion lacteum (Örley) in laboratory incubations in soil from a beechwood on limestone. The daily loss of C due to mucus excretion from the body surface and in casts was calculated as 0.2 and 0.5% of total animal C, respectively. The C loss due to mucus excretion by subadult or adult individuals of O. lacteum is assumed to account for 63% of total C losses (including mucus excretion and respiration) of the earthworms. In a second experiment we studied the incorporation of 14C from labelled soil, again from a beechwood on limestone, into the tissue of the endogeic earthworm species Aporrectodea caliginosa (Savigny). The results of this experiment indicate the existence of two C pools, one more labile and one more stable, in earthworms. It is assumed that the C investment for respiration and mucus excretion is derived from the labile C pool of endogeic earthworms.

Electronic Resource

1432-0789

Lignin decomposition ; Soil microcompartments ; White-rotted wood ; Brown-rotted wood ; Earthworm faeces ; Octolasion lacteum ; Fagus sylvatica

Springer Online Journal Archives 1860-2000

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Summary C mineralization of three different C-14-labelled lignin substrates (Klason-lignin, dioxane-lignin, lignocellulose) was investigated in four microcompartments, consisting of white-rotted beechwood (Fagus sylvatica L)., brown-rotted beechwood, earthworm [Octolasion lacteum (Örley)] faecal particles mixed with white-rotted beechwood, and earthworm feacal particles mixed with brown-rotted beechwood, incubated at 10°C for 193 days. Conversion of the labelled substrates to 14CO2 was low in both white-rotted and brown-rotted wood without faecal particles. Overall C mineralization followed the order Klason-lignin 〉 dioxane-lignin 〉 lignocellulose, indicating that there were different amounts of labelled contaminants in the lignin substrates. Lignin degradation was more pronounced in earthworm faeces mixed with wood materials, and overall C mineralization ranged between 4.4% and 6.3% of the inital C content. C mineralization of the lignin substrates increased considerably in faecal particles after about 90 days, presumably due to nutrient immobilization and microbial succession. The usefulness of the three lignin substrates in monitoring the time-course and extent of lignin degradation in soil microcompartments is discussed.

Electronic Resource

1432-0789

Substrate-induced respiration ; Microbial biomass ; Beech forest ; Soil aggregates ; Aggregate disruption ; Fagus sylvatica

Springer Online Journal Archives 1860-2000

Biology

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract We studied the effects of aggregates of different sizes on the soil microbial biomass. The distribution of aggregate size classes (〈2, 2–4, 4–10, 〉10 mm) in the upper mineral soil horizon (Ah layer) was very different in three sites (upper, intermediate, lower) in a beechwood (Fagus sylvatica) on a basalt hill (Germany). Aggregates of different sizes (〈2, 2–4, 4–10 mm) contained different amounts of C and N but the C:N ratios were similar. C and N contents were generally higher in smaller aggregates. The maximum initial respiratory response by microorganisms in intact aggregates and in aggregates passed through a 1-mm sieve declined with the aggregate size, but the difference was more pronounced in intact aggregates. Disruption of aggregates generally increased this response, particularly in 4- to 10-mm aggregates in the lower site. Basal respiration differed strongly among sites, but was similar in each of the aggregate size classes. Aggregate size did not significantly affect the specific respiration (μg O2 μg−1 microbial C h−1) nor the microbial: organic C ratio, but these parameters differed among sites. Microbial growth was increased strongly by passing the soil through a 1-mm sieve in each of the aggregate materials. The growth of microorganisms in disrupted aggregates was similar, and the effect of aggregate disruption depended on the growth of microorganisms in intact aggregates.

Electronic Resource

1432-184X

Springer Online Journal Archives 1860-2000

Biology

Abstract The decomposition of three different 14C-labeled cellulose substrates (plant holocellulose, plant cellulose prepared from 14C-labeled beech wood (Fagus sylvatica) and bacterial cellulose produced by Acetobacter xylinum) in samples from the litter and mineral soil layer of a beechwood on limestone was studied. In a long-term (154 day) experiment, mineralization of cellulose materials, production of 14C-labeled water-soluble compounds, and incorporation of 14C in microbial biomass was in the order Acetobacter cellulose 〉 holocellulose 〉 plant cellulose in both litter and soil. In general, mineralization of cellulose, production of 14C-labeled water-soluble compounds, and incorporation of 14C in microbial biomass were more pronounced, but microbial biomass 14C declined more rapidly in litter than in soil. In short-term (14 day) incubations, mineralization of cellulose substrates generally corresponded with cellulase and xylanase activities in litter and soil. Pre-incubation with trace amounts of unlabeled holocellulose significantly increased the decomposition of 14C-labeled cellulose substrates and increased cellulase activity later in the experiment but did not affect xylanase activity. The sum of 14CO2 production, 14C in microbial biomass, and 14C in water-soluble compounds is considered to be a sensitive parameter by which to measure cellulolytic activity in soil and litter samples in short-term incubations. Shorter periods than 14 days are preferable in assays using Acetobacter cellulose, because the decomposition of this substrate is more variable than that of holocellulose and plant cellulose.

Electronic Resource

2018-01-18

The American Society for Microbiology (ASM)

0022-538X

1098-5514

Medicine