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Physiological constraints from harsh environmental conditions, such as from calcium limitation on acidic soils, is expected not only to affect species richness, but also species abundance distributions. Also, the effects of amendments by calcium addition (soil liming) on these assemblage characteristics are poorly understood. Because of their sensitivity towards calcium availability, we use snails as model organisms and integrate field surveys and literature data. Temperate forest snail data supported a rule-of-thumb calibration with pH measurements in water being one unit higher than in KCl buffer. The resulting large data set suggests stepwise changes in snail richness that occur at transitions in soil buffer systems, especially at pH 3.2. Species abundance distributions follow the logseries model in most soil buffer systems, except for the iron buffer range (pH ≤3.2) where they swap to the geometric model. Our findings thus suggest several smaller soil pH thresholds for snail assemblages associated with shifts between soil buffer systems, and a tipping point at the threshold to pH ≤3.2. Liming with ground carbonate rocks is a technique to temporarily increase soil pH and calcium availability in forest soils, but its effects on snail assemblages produced inconsistent results that did not meet expectations from the ameliorated soil pH and might warrant a re-evaluation of liming applications.

Historical land use provides long-term field experiments that give valuable clues for ecosystem management and habitat restoration. We hypothesized that remnants of a small-scale charcoal-ore industry that ceased more than a century ago still affect soil properties and the litter-dwelling fauna of a beech forest on rendzina soil (pH 4–6.5). We sampled the remains of charcoal kilns, small mining pits, and mounds of dugout material. Soils from kilns displayed increased carbon and nutrient contents and soils from kilns and in pits tended to be moister than that from all other locations. Leaf litter accumulated in the pits. Most mesofauna taxa occurred independent of the modifications, whereas larger-sized Collembola and many macrofauna taxa (Aranea, Chilopoda, Diplopoda, Isopoda, Coleoptera, and Gastropoda) were more abundant in the pits. Snails are highly sensitive to microclimatic fluctuations and structural changes and thus were used to compare man-made structures with natural ones: assemblages from kilns equaled those from the unmodified forest floor, assemblages from pits resembled those from adjacent to coarse woody debris (CWD), and assemblages from mounds resembled those from outcrops and tree bases. The outcrops were the local keystone structure, but mining pits and CWD added to species richness as they provided shelter for hygrophilous species. We thus recommend maintaining or creating a diversified soil surface structure in post-mining land reclamation to accumulate organic matter and nutrients and to buffer microclimatic extremes.

The open-cast lignite mine “Hambach” (NW-Germany) and the accompanying land reclamation replace a large ancient forest. Reclamation of an 1000 ha large overburden dump started 25 years ago and is still in progress. Reclamation methods comprise combinations of different topsoil dumping techniques and reclamation measures such as seeding or afforestation. In accordance with the spatial heterogeneity hypothesis, we hypothesize that beetle assemblages from sites where the topsoil was left structured are more diverse than those from sites with levelled topsoil, and that richly structured mid-successional sites harbour more heterogeneous assemblages than afforested sites. We tested the influence of environmental variables on assemblage characteristics of pitfall-trapped beetles from 17 sites on the overburden dump. The results are based on 35,588 individuals from 339 species. Species assemblages differed significantly between almost all sites. Habitat age did not affect assemblage characteristics, while species richness was significantly influenced by surface structure. Sites that were not levelled and that additionally included pits that slope down for several meters exhibited the highest species richness. Abundance of beetles increased in parallel to the canopy cover, whereas assemblage heterogeneity (MVDISP) decreased. Successional and grassland sites usually exhibited higher diversity (Fisher's α) than afforested sites, but diversity was not significantly predicted by a single environmental factor. Instead, diversity increased along with increasing MVDISP-values. Afforestations speed up the successional process and some euryecious forest species are already well established, but stenecious forest specialists have not yet been found.

Base cation depletion due to soil acidification is a major environmental problem which can disrupt proper ecosystem functioning. We investigated nine mesic broad-leaved forests growing on Devonian sediments of the Rhenish Shield (Germany) and investigated the effect of coarse woody debris (CWD). The forests grow on soils originating from different parent material (graywacke, slates, dolostone) with upper soil pH-values ranging from 3.0 to 7.0. We analyzed soil chemistry, soil microbial parameters and the density of litter-dwelling detritivores (snails, slugs, woodlice and millipedes) to assess the influence of both acidification and CWD. The forests were classified according to their (Ca + Mg + K)/Al molar ratios into groups with ratios of either 2+ and Mg 2+ availability and an improved (Ca + Mg + K)/Al molar ratio. The presence of CWD also enhanced soil microbial biomass, the density of detritivores and species richness of snails, slugs and millipedes. Consequently, coarse woody debris influences nutrient fluxes and decreases the acidification-related risk of tree damage.

In many afforested reclamation sites as well as in commercial forests naturally settled shrubs or trees (“non-target species”; NTS) are cut down to improve the growth of the target trees (TT). In afforested oak plantations ( Quercus robur ) of the Rhineland (Germany) the NTS broom ( Cytisus scoparius ) and birch ( Betula pendula ) can occur in high densities during the first decades of succession. Hazel ( Corylus avellana ) is a common shrub in the understory of commercial oak forests ( Quercus petraea ). We studied the influence of these NTS on selected physical, chemical and biotic soil properties in cultures of oak (TT). Soil samples taken under single oak trees were compared with samples taken under broom and birch at afforested reclamation sites of different age (2, 9, 13 years) and with samples taken under hazel in an 80-year-old oak forest. At initial stages of succession (2 years) all of the investigated soil properties indicated a higher soil quality under broom than under oak. However, the advantage of broom was less evident in a later stage of succession (9 years). Birch (13 years) and hazel (80 years) only improved soil chemical properties. The soil pH and the content of Mg 2+ were significantly higher under birch, the contents of Ca 2+ , Mg 2+ and PO 4 3− were significantly higher under hazel than under oak ( p =0.05). The results demonstrate that the selected NTS improve soil quality in afforested and commercial oak forests. This effect is pronounced under the influence of broom at initial stages of soil development.

We studied the soil properties of 18-year-old plantations beneath the crowns of the native sessile oak ( Quercus petraea ) and of the introduced red oak ( Quercus rubra ) growing on reclaimed lignite open-cast mines. The soil properties of both plantations, which are growing on either highly fertile (loess deposits, silty loam) or on low fertile (mixture of loess and sand deposits, clayed sand) soil, were measured and compared with values taken from 2-year-old Quercus robur plantations. In plantations of Q. petraea we generally found higher values of total carbon (C org ) and total nitrogen (N tot ) in the upper soil, although the amount of organic matter in the O-horizon did not significantly differ. Soils of Q. petraea plantations also exhibited higher values for microbial and faunal life. For example, microbial activity, the respiratory quotient ( q CO 2 ) and C-mineralization were about twice as high as for the Q. rubra plantations. Collembola and mites (Oribatei), both belonging to the soil mesofauna, reached higher densities in the Q. petraea plantations. When growing on highly fertile soils, the amount of soil nutrients (K + , Ca 2+ , Mg 2+ , and PO 4 3− P) did not differ between the two plantations. However, when oak trees grew on the less-fertile soil, the amount of soil nutrients was significantly lower beneath red oak. The amount of soil nutrients beneath red oak was even lower than beneath 2-year-old Q. robur plantations; the soil properties of which are almost at the beginning stage of succession. The results suggest that nutrient depletion beneath red oak when compared to sessile oak is caused both by increased immobilization into woody biomass, and by increased recalcitrance of organic matter.

In sloping oak forests of the German low mountain range high wild boar (Sus scrofa) and red deer (Cervus elaphus) population densities may affect soil ecological processes by grubbing, grazing, trampling and dunging. We simulated wild boar grubbing in a fenced exclosure and an unfenced replicate and established two adjacent control plots, one fenced, the other unfenced. We evaluated if repeated soil bioturbation and game exclusion by fencing influence soil texture, soil chemical and soil biotic properties in the upper soil over a time period of 2 years. Soil bioturbation was conducted in November 2000 and 2001 creating a grubbing pattern similar to that found in naturally grubbed areas. Soil and fauna sampling was performed in spring and fall of the years 2001 and 2002. Soil bioturbation did not affect soil texture, pH and the contents of organic carbon and nitrogen. In contrast, the contents of potassium and magnesium, the microbial activity and the abundance of saprophageous and predatory soil arthropods were generally lower in grubbed plots compared to ungrubbed control plots (p≤0.05). The exclusion of game did not improve soil quality. On the contrary, microbial activity and the contents of organic carbon and total nitrogen were elevated outside the fenced exclosure (p≤0.05) which may be related to the deposition of urine and dung. Our study found that large mammals affect soil nutrient cycling in sloping oak forests either directly by the deposition of urine and dung or indirectly by accelerating nutrient leaching and disturbing the decomposer system in the soils.

The study area is located in the low mountain range of Central Europe (Eifel) and characterized by a marked relief and high game densities. Especially red deer populations, calculated at 20 ind./100 ha, surpass the carrying capacity of the forests observed. Trampling (by red deer and moufflon) and rooting (wild boar) result in extensive soil disturbances, visible as soil profile mixture and soil erosion.

Reclaimed lignite open-cast mine areas in the Rhineland are covered by a mixture of loess and sand deposits containing organic material that originates from the upper quartary soil which has been taken from the front of the mining path. Consequently, the soil fauna that has established itself on the reclaimed open-cast mine areas may result from the primary succession and also from species that are carried to the dumping mines and are able to survive the dumping process. The reclaimed landscape consists of a regular structural pattern of crests and troughs. The troughs provide appropriate habitats for establishing a rich and diverse fauna with higher densities of almost all animal groups investigated, with enhanced microbial activity and higher values of available macronutrients. In terms of plant growth, the physical and chemical conditions found in the troughs exceeded the conditions found on the crests. From laboratory studies we made the following conclusions: (1) environmental conditions in the troughs were improved not only by erosion, but additionally by the soil fauna that directly enhanced microbial activity and indirectly increased the availability of macronutrients; (2) soil animals improved soil quality by increasing the pH-values, increasing the ammonium–nitrogen content and decreasing the content of aluminium ions; and (3) a multiple-species system is able to improve soil quality more effectively than a single-species system.

In April 1996, we collected soil samples in thevicinity of a magnesite plant at Lubenik, southernSlovakia, and screened them for soil microbial biomassand activity. Six investigated sites were chosen alonga transect, with distances ranging from 600 to 8000 mfrom the plant, to represent a gradient ofintoxication. Soil microbial cellulase activity,respiration, biomass, metabolic quotient of the soilmicrobiota, and numbers of platable fungi increasedwith increasing distance from the plant, i.e.decreasing degree of intoxication. The observedgradients of soil microbial characteristics of theinvestigated sites reflect the physico-chemical soilparameters and the floristic characteristics of thesesites, and may be used to predict transitory changesduring amelioration.