Habitat management and patterns of predation of Northern Lapwings on wet grasslands: The influence of linear habitat structures at different spatial scales

In managed landscapes, habitat structure is frequently manipulated through the creation of features such as tracks, hedges, and waterways. If predator and prey activity are concentrated around these features, levels of predation may be elevated in these landscapes. This issue is of particular importance when habitat structures are used to attract species of conservation concern. For example, the installation of linear waterways in wet grasslands is a common form of habitat management to benefit breeding waders and wader nests and foraging chicks tend to be aggregated around wet features. If predator activity is also focused around these features, and if their linearity increases the probability of prey being located, then the conservation benefits of this management technique may be eliminated. We explore predator movement in relation to the structure and complexity of linear wet features within a lowland wet grassland landscape. We examine patterns of nest and chick predation in lapwing (Vanellus vanellus) at the whole-site, between-field and within-field scales. Mammalian predators were responsible for the majority of nest predation. However, we found no evidence that mammalian predators used linear wet features disproportionately within the landscape, or that wet feature distribution influenced the probability of nest or chick predation. At the whole-site scale, nest predation rates were significantly higher in areas with greater predator presence and lowest where the number of breeding neighbours was high. Thus, predation levels were influenced by large-scale patterns of predator presence and lapwing density but not by the use of linear wet features as a habitat management tool. Managing predator impacts is therefore likely to require empirical assessments of local predator distribution and abundance in order to target measures effectively.     

Possible role of ectomycorrhizal fungi in cycling of aluminium in podzols

Budget studies in boreal podzols indicate a considerable upward transport of aluminium (Al) from the mineral soil into the organic horizon. In this paper we studied if ectomycorrhizal (EcM) fungi can be involved in this upward transport via their extramatrical hyphae. We tested the use of gallium (Ga) as proxy for Al. Transport of Al through EcM hyphae was studied in vitro in a two-compartment Petri dish system. Two of the five fungal isolates tested transported Al. Using Ga instead of Al revealed the same trend in these systems, confirming the use of Ga as proxy for Al. Upward transport of Ga was studied in an artificial podzol. Pinus sylvestris seedlings were colonised by a natural community of EcM fungi from fresh forest soil. Gallium addition to the mineral soil led to increased Ga content in roots in the organic horizon and in the shoot. Upward Ga allocation was significantly higher when roots were excluded from the mineral soil by a mesh, only allowing fungal mycelium to grow through. We conclude that at least some EcM fungi transport Al and that Ga, and probably also Al, can be transported upwards by EcM fungal hyphae in a podzol system. These findings support the hypothesis that EcM fungi play a role in upward transport of Al in podzols.     

Sediment tracers in water erosion studies: current approaches and challenges

Introduction

Interest in the use of sediment tracers as a tool to complement traditional water erosion or deposition measurements has increased due to the additional information they provide, such as sediment source identification, tracking of sediment movement across the landscape at various temporal and spatial scales, and estimation of soil erosion rates. For these reasons, the utility and robustness of sediment tracing approaches using a wide range of substances and soil properties have been evaluated in numerous studies.

Conclusions

A review of established tracing approaches identified five distinct groups of tracing approaches: fallout radionuclides, rare earth elements, soil magnetism and magnetic substances, other tracers, and sediment fingerprinting techniques. This paper describes the basic theory of each tracing approach in assessing soil erosion and sediment redistribution, describing their methodology and main applications, and summarizing the commonalities and differences between the approaches. It also identifies research gaps and future trends.     

Production and dissolution rates of earthworm-secreted calcium carbonate

Earthworms secrete granules of calcium carbonate. These are potentially important in soil biogeochemical cycles and are routinely recorded in archaeological studies of Quaternary soils. Production rates of calcium carbonate granules by the earthworm Lumbricus terrestris L. were determined over 27 days in a range of soils with differing chemical properties (pH, organic matter content, water holding capacity, bulk composition, cation exchange capacity and exchangeable cations). Production rate varied between soils, lay in the range $0–0.043{\text{mmol}}_{{\text{CaCO}}_3}$ (0–4.3 mg) earthworm^?1 d^?1 with an average rate of $8\times {10}^{?3}{\text{mmol}}_{{\text{CaCO}}_3}$ (0.8 mg) earthworm^?1 d^?1 and was significantly correlated (r = 0.68, P ≤ 0.01) with soil pH. In a second experiment lasting 315 days earthworms repeatedly (over periods of 39–57 days) produced comparable masses of granules. Converting individual earthworm granule production rates into fluxes expressed on a per hectare of land per year basis depends heavily on estimates of earthworm numbers. Using values of 10–20 L. terrestris m^?2 suggests a rate of $18–3139{\text{mol}}_{{\text{CaCO}}_3}{\text{ha}}^{?1}{\text{yr}}^{?1}$. Data obtained from flow-through dissolution experiments suggest that at near neutral pH, granule geometric surface area-normalised dissolution rates are similar to those for other biogenic and inorganic calcites. Fits of the data to the dissolution relationship r = k(1 ? Ω)ⁿ where r = dissolution rate, k = a rate constant, Ω = relative saturation and n = the reaction order gave values of k = 1.72 × 10^?10 mol cm^?2 s^?1 and n = 1.8 for the geometric surface area-normalised rates and k = 3.51 × 10^?13 mol cm^?2 s^?1 and n = 1.8 for the BET surface area-normalised rates. In 196 day leaching column experiments trends in granule dissolution rate referenced to soil chemistry corresponded to predictions made by the SLIM model for dissolution of limestone in soil. If soil solution approaches saturation with respect to calcium carbonate, granule dissolution will slow or even stop and granules be preserved indefinitely. Granules have the potential to be a small but significant component of the biogeochemical cycling of C and Ca in soil.     

Using DNA from museum specimens to preserve the integrity of evolutionarily significant unit boundaries in threatened species

Use of DNA from museum samples is a powerful tool to directly establish historical ESU boundaries in areas where populations of a species have been extirpated. The brush-tailed rock-wallaby (Petrogale penicillata) has suffered extensive reductions in range and population size since European settlement in Australia. Populations of this species have been grouped into three putative evolutionarily significant units (ESUs) which were likely once contiguous along the south-east coast of Australia. However, there is currently a gap of ∼320 km between extant populations of the southern and central ESUs. Conservation plans for the brush-tailed rock-wallaby include re-introductions of animals to locations within their former range. In order to preserve the historic geographic integrity of the genetic lineages within the species, it is necessary to map the boundary between the southern ESU and central ESU to allow more informed management decisions about which lineages should be used to re-stock specific geographic locations. We have extracted DNA from samples from museum specimens that come from locations between the southernmost extant colony of the central ESU and the remaining wild colony of the southern ESU. We sequenced a 177 bp interval of the left domain of the mitochondrial DNA control region and used phylogenetic analysis to group obtained sequences with previously published sequences belonging to the three ESUs. We have extended the range of the central ESU southwards and the range of the southern ESU northwards such that the gap between the ESUs is now approximately 160 km. We recommend that, where suitable historical museum collections exist, this technique be incorporated into re-introduction plans for other threatened species.     

N-linked glycan profiling of mature human milk by high-performance microfluidic chip liquid chromatography time-of-flight tandem mass spectrometry

N-Linked glycans of skim human milk proteins were determined for three mothers. N-Linked glycans are linked to immune defense, cell growth, and cell-cell adhesion, but their functions in human milk are undetermined. Protein-bound N-linked glycans were released with peptidyl N-glycosidase F (PNGase F), enriched by graphitized carbon chromatography, and analyzed with Chip-TOF MS. To be defined as N-glycans, compounds were required, in all three procedural replicates, to match, within 6 ppm, against a theoretical human N-glycan library and be at least 2-fold higher in abundance in PNGase F-treated than in control samples. Fifty-two N-linked glycan compositions were identified, and 24 were confirmed via tandem mass spectra analysis. Twenty-seven compositions have been found previously in human milk, and 25 are novel compositions. By abundance, 84% of N-glycans were fucosylated and 47% were sialylated. The majority (70%) of total N-glycan abundance was composed of N-glycans found in all three milk samples.     

A Potential Solution to Mitigate Phosphorus Release Following Clearfelling in Peatland Forest Catchments

Since the 1950s, large areas of upland peat have been afforested in northern European countries. Due to the poor phosphorus (P) adsorption capacity and low hydraulic permeability in blanket peat soil and increased labile P sources, harvesting these blanket peat forests can significantly increase P concentrations in the receiving aquatic systems. This paper briefly reviews the current management practices on the control of P releases from forestry in Ireland and the UK, and proposes a possible novel practice??grass seeding clearfelled areas immediately after harvesting, which should reduce P release from blanket peat forest harvesting. The study was conducted in the Burrishoole Catchment in the west of Ireland. A field trial was carried out to identify the successful native grass species that could grow quickly in the blanket peat forest. The two successful grass species??Holcus lanatus and Agrostis capillaris??were sown in three blanket peat forest study plots with areas of 100, 360, and 660 m² immediately after harvesting. Areas without grass seeding were used as controls. One year later, the P content in the aboveground vegetation biomass of the three study plots were 2.83, 0.65, and 3.07 kg P?ha^?1, respectively, which were significantly higher than the value of 0.02 kg P?ha^?1 in the control areas. The water extractable phosphorus in the three study plots were 8.44, 9.83, and 6.04 mg?(kg dry soil)^?1, respectively, which were lower than the value of 25.72 mg?(kg dry soil)^?1 in the control sites. The results indicate that grass seeding of the peatland immediately after harvesting can quickly immobilize significant amounts of P and warrants additional research as a new Best Management Practice following harvesting in the blanket peatland forest to mitigate P release.     

Evaluation of Amendments to Control Phosphorus Losses in Runoff from Dairy-Soiled Water

Amendments with the potential to reduce phosphorus (P) losses from agricultural grassland arising from the land application of dairy-soiled water (DSW) were investigated. Optimal application rates were studied, and associated costs and feasibility were estimated. First, batch tests were carried out to identify appropriate chemicals or phosphorus sorbing materials to control P in runoff from DSW. Then, the best four treatments were examined in an agitator test. In this test, soil??placed in a beaker??was loaded with DSW or amended DSW at a rate equivalent to 5 mm ha^?1 (the maximum permissible application rate of DSW allowable in a 42-day period in Ireland). The soil was overlain with continuously stirred water to simulate runoff on land-applied DSW. Optimum application rates were selected based on percentage removal of dissolved reactive phosphorus in overlying water and the estimated cost of amendment. The costs of the amendments, per cubic metre of DSW, increased in the order: bottom ash (1.55 ?), alum (1.67 to 1.92 ?), FeCl₂·4H₂O (3.55 to 8.15 ?), and lime (20.31 to 88.65 ?). The feasibility of the amendments, taking into account their cost, potential adverse effects, public perception, and their performance, decreased in the order: alum?>?FeCl₂·4H₂O?>?bottom ash?>?lime. Amendments to DSW could be introduced in critical source areas??areas where high soil test P and direct migration pathways to a receptor overlap.     

Size Does Matter: Application-driven Approaches for Soil Metagenomics

Metagenomic analyses can provide extensive information on the structure, composition, and predicted gene functions of diverse environmental microbial assemblages. Each environment presents its own unique challenges to metagenomic investigation and requires a specifically designed approach to accommodate physicochemical and biotic factors unique to each environment that can pose technical hurdles and/or bias the metagenomic analyses. In particular, soils harbor an exceptional diversity of prokaryotes that are largely undescribed beyond the level of ribotype and are a potentially vast resource for natural product discovery. The successful application of a soil metagenomic approach depends on selecting the appropriate DNA extraction, purification, and if necessary, cloning methods for the intended downstream analyses. The most important technical considerations in a metagenomic study include obtaining a sufficient yield of high-purity DNA representing the targeted microorganisms within an environmental sample or enrichment and (if required) constructing a metagenomic library in a suitable vector and host. Size does matter in the context of the average insert size within a clone library or the sequence read length for a high-throughput sequencing approach. It is also imperative to select the appropriate metagenomic screening strategy to address the specific question(s) of interest, which should drive the selection of methods used in the earlier stages of a metagenomic project (e.g., DNA size, to clone or not to clone). Here, we present both the promising and problematic nature of soil metagenomics and discuss the factors that should be considered when selecting soil sampling, DNA extraction, purification, and cloning methods to implement based on the ultimate study objectives.