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Braunschweig, Germany

Petersen U.,University of Gottingen | Petersen U.,Thunen Institute of Biodiversity | Wrage-Monnig N.,University of Gottingen | Wrage-Monnig N.,Rhine-Waal University of Applied Sciences | Isselstein J.,University of Gottingen
International Journal of Biodiversity Science, Ecosystems Services and Management | Year: 2013

Herbicide application on permanent grassland to reduce weeds and improve forage quality is common agricultural practice. However, it still remains unclear how long it takes for the herbicide-disturbed swards to recover in terms of yield and forage quality. In a removal experiment in the Solling Uplands (Germany), the sward composition of permanent grassland had been manipulated by herbicides in order to obtain either relatively pure grass swards or swards with comparatively large amounts of forbs and legumes, in addition to untreated control swards. The short-term resilience of these sward types was examined under a gradient of management intensity regulated by both cutting regime and fertilizer supply. In the next growing season, the yield did not differ among any of the three sward types regardless of the management regime. All disturbed swards showed a complete recovery in terms of biomass. Yield was only influenced by functional sward characteristics across all disturbance treatments; the growth form of the dominant species determined the yield in fertilized plots. For the variation in forage quality (crude protein, water-soluble carbohydrates and fibre content), the functional group identity of the remaining vegetation was important, but management had a much larger influence than vegetation. © 2013 Copyright Taylor and Francis Group, LLC. Source

Strohbach M.W.,University of Massachusetts Amherst | Strohbach M.W.,Thunen Institute of Biodiversity | Lerman S.B.,University of Massachusetts Amherst | Warren P.S.,University of Massachusetts Amherst
Landscape and Urban Planning | Year: 2013

Green space is an important component of the urban landscape, providing ecosystem services for city dwellers and supporting biodiversity. In many cities, green space is concentrated in large areas, while the rest is dispersed in small patches like pocket parks, gardens or street trees. Such small-scale green space is often the target of greening initiatives but little is known about their value for supporting and conserving biodiversity. To assess the value of such initiatives for biodiversity, we used birds as an indicator. We examined bird communities at small greening projects (n=12), nearby randomly chosen urban sites (n=12), and large parks (n=6) in Boston, MA, in relationship to underlying landscape patterns. Our results show that large parks harbor a distinct and rich bird community. The other sites, regardless of the presence of greening projects, were very similar to each other. However, most sites with greening projects had higher species richness than the random urban site in their vicinity. The main factor associated with this appears to be the patch size of green space and to a lesser extent, tree cavities. Even small increases of a few hundred square meters were associated with an increase in bird richness. Having more trees with cavities was also beneficial for species richness. Small greening projects appear to be most valuable for urban biodiversity if they target preserving, increasing and connecting existing green space. This may represent a tradeoff with environmental justice criteria for new green space. © 2013 Elsevier B.V. Source

Moos J.H.,Thunen Institute of Organic Farming | Schrader S.,Thunen Institute of Biodiversity | Paulsen H.M.,Thunen Institute of Organic Farming | Rahmann G.,Thunen Institute of Organic Farming
Applied Soil Ecology | Year: 2016

Reduced tillage has several advantages over conventional tillage (CT), including the promotion of earthworm communities and the reduction of input of energy and labour. However, its application in organic farming is mainly hindered through increasing weed pressure. One way to counteract this drawback might be to introduce occasional reduced tillage (ORT), which means applying methods of reduced tillage only in combination with selected crops. Against this background we hypothesized that (i) ORT rapidly promotes biomass, abundance and species richness of earthworm communities and that (ii) ORT generates a financial surplus for farmers. Therefore, a field experiment was established for triticale (x Triticosecale) cultivation on loamy soils in Northern Germany. The influence of tillage regimes on earthworms was investigated in a non-randomized design with n = 3 fields for the ORT and CT treatment. Earthworm biomass, abundance and species richness were investigated in October 2012 and in April and October 2013. Yields were determined for the three fields under each tillage system, each field with four non-randomized replicates, before harvest in 2013. The ORT treatment consisted of two to three tillage operations prior to seeding with a maximal cultivation depth of 15 cm and without ploughing, whereas the CT treatment consisted of a ploughing depth of 25-30 cm and one to four other steps for seedbed preparation prior to seeding. In total, seven earthworm species were identified. Our data revealed that earthworm biomass was significantly reduced under CT, both four weeks and about seven months after tillage. This effect holds true for the number of earthworm individuals in autumn (four weeks after ploughing), but not for the number of earthworm individuals in spring (seven months after ploughing). Results of contribution margin analysis showed no consistent trend referring to tillage measures. Two fields, which performed well under CT, showed a financial surplus (+24% and +13%) when managed with ORT. At the same time one field, performing poorly under CT, generated financial deficits (-10%) under ORT. Overall ORT had immediate positive effects on earthworm populations. Furthermore, this management scheme might have positive effects on the economic outcomes of organic crop rotations if overall growing conditions are sufficient. Along with methods usually applied to investigate earthworm performance, we checked whether the number of surface casts could help estimate earthworm performance. It became apparent that the number of surface casts cannot be used as a general predictor of earthworm performance. The number of individuals of Lumbricus terrestris, the number of anecic individuals and the total earthworm biomass can be estimated the most reliable by counting surface casts. © 2016 Elsevier B.V. Source

Dauber J.,Thunen Institute of Biodiversity | Cass S.,Trinity College Dublin | Gabriel D.,Thunen Institute of Biodiversity | Harte K.,Trinity College Dublin | And 3 more authors.
GCB Bioenergy | Year: 2015

Increasing crop productivity to meet rising demands for food and energy, but doing so in an environmentally sustainable manner, is one of the greatest challenges for agriculture to date. In Ireland, Miscanthus × giganteus has the potential to become a major feedstock for bioenergy production, but the economic feasibility of its cultivation depends on high yields. Miscanthus fields can have a large number of gaps in crop cover, adversely impacting yield and hence economic viability. Predominantly positive effects of Miscanthus on biodiversity reported from previous research might be attributable to high crop patchiness, particularly during the establishment phase. The aim of this research was to assess crop patchiness on a field scale and to analyse the relationship between Miscanthus yield and species richness and abundance of selected taxa of farmland wildlife. For 14 Miscanthus fields at the end of their establishment phase (4-5 years after planting), which had been planted either on improved grassland (MG) or tilled arable land (MT), we determined patchiness of the crop cover, percentage light penetration (LP) to the lower canopy, Miscanthus shoot density and height, vascular plants and epigeic arthropods. Plant species richness and noncrop vegetation cover in Miscanthus fields increased with increasing patchiness, due to higher levels of LP to the lower canopy. The species richness of ground beetles and the activity density of spiders followed the increase in vegetation cover. Plant species richness and activity density of spiders on both MT and MG fields, as well as vegetation cover and activity density of ground beetles on MG fields, were negatively associated with Miscanthus yield. In conclusion, positive effects of Miscanthus on biodiversity can diminish with increasing productivity. This matter needs to be considered when assessing the relative ecological impacts of developing biomass crops in comparison with other land use. © 2013 John Wiley & Sons Ltd. Source

Hemkemeyer M.,Thunen Institute of Biodiversity | Christensen B.T.,University of Aarhus | Martens R.,Thunen Institute of Biodiversity | Tebbe C.C.,Thunen Institute of Biodiversity
Soil Biology and Biochemistry | Year: 2015

Due to differences in mineralogical composition and organic matter density, soil particle size fractions (PSF) provide different surface properties and micro-environments, which may affect the adsorption of chemicals and select for distinct microbial communities. Using soils from a long-term fertilisation experiment, we examined the structural diversity of microbial communities associated with different PSF and their potential to mineralise two organic pollutants (phenol and 2,4-dichlorophenol (DCP)). The soils were taken from 0 to 18 cm depth of arable field plots that have been kept unfertilised (UNF), mineral fertilised (NPK), or treated with animal manure (AM) for 117 years. Sand, including particulate organic matter (POM), coarse silt, fine silt, and clay were isolated by gentle ultra-sonication, wet-sieving and centrifugation. Animal manuring increased the abundance of the three microbial domains Bacteria, Archaea and Fungi, with coarse silt being most responsive. The impact of manuring declined with decreasing particle size. Genetic profiling indicated that the composition of the bacterial communities was primarily shaped by soil particle size classes, while archaea responded predominantly to fertilisation. Particle size as well as fertilisation was equally important in structuring the fungal communities. All PSF showed capacity for phenol mineralisation with rates correlating negatively with particle size (except for the sand-POM fraction), and long-term fertilisation enhanced the mineralisation potential. In contrast, DCP mineralisation was associated with the clay fraction only and was highest for soil treated with mineral fertiliser. This study demonstrates that PSF harbour structurally distinct microbial communities with different functional potentials for mineralising organic pollutants. © 2015 Elsevier Ltd. Source

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