The local responses of aquatic ecosystems to adjacent grassland conservation: Can streams of dreams exist in a degraded riverscape?

1. Landscape homogenization and the removal of riparian areas have altered stream ecosystems worldwide. Numerous conservation programmes attempt to improve water quality and increase instream habitat heterogeneity to elicit desired biological responses. However, the effectiveness of many conservation efforts on isolated stream fragments remains unknown, especially in grassland regions.
2. The effects of grassland conservation practices and the re-establishment of riparian corridors in the James River basin, South Dakota (USA) on stream water quality, habitat availability and aquatic macroinvertebrate and fish assemblages were studied in an agriculturally dominated prairie landscape.
3. Grassland conservation efforts may have repaired riparian condition, reduced turbidity and created more diverse instream habitat complexes at conservation sites based on comparisons with paired reference reaches. Reference sites were relatively homogeneous, with prevalent siltation, bank erosion and disturbances to the riparian vegetation. Owing to significant riparian vegetation development, overhanging and aquatic vegetation, benthic detritus and woody materials were significantly more common at conservation reaches.
4. Restoration efforts that assume ‘if you (re-)build it, they will come’ (i.e. the ‘field of dreams’ hypothesis) underestimate other important barriers to biodiversity restoration in dynamic, grassland riverscapes. Although aquatic organisms in grassland ecosystems are adapted to rapidly inhabit available habitats, the development of niche space at conservation reaches did not directly result in colonization by aquatic life.
5. Grassland management actions did not address stream connectivity issues or overcome land use influences elsewhere in the riverscape that may govern the responses of aquatic macroinvertebrates and fish. Stream fragmentation and continuing, damaging land use patterns seemed to exceed the positive effects of restoring isolated stream reaches in these heavily degraded catchments. Catchment-scale management strategies that combine reach-level restoration actions with efforts to improve connectivity are likely to be more successful in degraded riverscapes.

     

Spot-application of fungicide for wild blueberry using an automated prototype variable rate sprayer

Wild blueberry producers apply fungicide uniformly without considering significant bare spots in the field. The wrong or over use of fungicide in bare spots results in an increased cost of production and threatens the environment. An automated prototype variable rate (VR) sprayer was used for spot-application (SA) of Chlorothalonil (Bravo^®) fungicide in a wild blueberry field. Eighteen 6.1 m wide test tracks were selected in the field and bare spots were mapped using a real-time kinematics-global positioning system (RTK-GPS). Six plots were selected randomly for three different application rates. Water sensitive papers (WSP) were placed in foliage and bare spots in SA and uniform-application (UA) tracks. The percent area coverage (PAC) of WSP with both SA and UA in foliage and bare spot areas were calculated. Plant growth parameters were measured from all 108 randomly selected plots in SA, UA and control (CN) tracks for comparison. Plant images were taken over six selected plots in each of the 18 tracks. Images were analyzed using custom developed software to calculate the percentage of green pixels (PGP) for determining the effect of Bravo^® on plant health. Fruit yield parameters were also measured from selected plots for comparison. Non-significance of the t test for SA versus UA plant targets’ PAC indicated that there was no significant bias in the SA with saving (9.90–51.22 %) and SA was accurate. Bravo^® did not show any significant difference on plant growth parameters among SA, UA and CN. However, PGP, floral bud and harvestable yield of SA and UA were significantly increased over CN. Therefore, a VR sprayer could be used for SA of fungicides in wild blueberry cropping system to reduce chemical usage and maintain crop productivity.     

Sensitivity of plants to acidic soils exemplified by the forest grass Bromus benekenii

The aim of this paper is to study the role of Al- and H-ions, base cation deficiency and N-nutrition as solely NH₄ in disturbing plant growth on acid soils. Effects of these factors on growth of the forest grass Bromus benekenii were studied experimentally and in the field and compared to other deciduous forest plants. Bromus benekenii is most frequent at pH >4.5 (soil solution) and absent at pH 3.8. In a pot experiment using an acid soil of pH 3.3, raised by steps to pH 5.2 by carbonate addition, growth of Bromus benekenii and nine other species (out of 17) was limited at pH <4.1. Toxicity of H-ions to Bromus benekenii was confirmed in a solution experiment at pH ≤4.2. Al-toxicity occurred at low Al-concentrations (20 μM) in Bromus benekenii and nine other tested species. Base cation (Ca+Mg) mitigation of Al-toxicity was found in a factorial solution experiment. Our experiments also indicate that H- and Al-ions interact in a way that makes combined treatments equally toxic as concentrations of H-or Al-ions alone. Incubation experiments showed that soil nitrification is retarded in acid soils. This may affect Bromus benekenii as it was most demanding on NO₃-availability out of 15 species in a solution experiment. Only 50% growth was attained in a NH₄- as compared to a NH₄+NO₃-treatment. Comparing experimental results with field data, we conclude that H- and Al-toxicity and unfavourable N-nutrition (as solely NH₄) to a similar extent may explain the acidifuge behaviour of field layer plants.     

Tree Establishment for a Temperate Agro-forest in Central Appalachia,USA

Small farms in Appalachia are economically challenged due to complex topography and soil constraints that limit productivity. Most farms have considerable acreage in forest, some of which is on the least productive sites, which contributes little income. The purpose of this study was to determine management and microclimate impacts on the establishment of an agro-forest for increasing the economic value of the forested land resource. A 1.2 ha forest clear-cut was planted with red oak (Quercus rubra) as the desired mature forest species alternated with rows of Chinese chestnut (Castanea mollissima), pawpaw (Asimina triloba), hazelnut (Corylus americana), and white pine (Pinus strobus) for generating income as the forest matures. Oak and chestnut required protection from deer. Oak had the lowest survival rate (61%) and chestnut had the highest survival rate (94%). While providing protection, Tubex plastic tubes also resulted in spindly tree growth. Plastic tubes did, however, improve pawpaw survival. Oak did best on well-drained locations. Chestnut and hazelnut were negatively impacted by forest edge more than oak or pawpaw. Overall there was a high degree of variability in tree growth suggesting that on low productivity sites, a planting density substantially higher than the desired final stand may be warranted to optimize the tree-vigor/micro-site match. The U.S. Government’s rights to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

Structure and function of lipopolysaccharide binding protein

The primary structure of lipopolysaccharide binding protein (LBP), a trace plasma protein that binds to the lipid A moiety of bacterial lipopolysaccharides (LPSs), was deduced by sequencing cloned complementary DNA. LBP shares sequence identity with another LPS binding protein found in granulocytes, bactericidal/permeability-increasing protein, and with cholesterol ester transport protein of the plasma. LBP may control the response to LPS under physiologic conditions by forming high-affinity complexes with LPS that bind to monocytes and macrophages, which then secrete tumor necrosis factor. The identification of this pathway for LPS-induced monocyte stimulation may aid in the development of treatments for diseases in which Gram-negative sepsis or endotoxemia are involved.     

Colonisation by arbuscular mycorrhizal and fine endophytic fungi in four woodland grasses – variation in relation to pH and aluminium

Acidic soils are harsh environments for plants. One of the major problems is the potential toxicity of aluminium (Al) and hydrogen ions at a pH below 5; another is the shortage of nutrients usually accompanying soil acidity. The aim of this study was to elucidate the relationship between arbuscular mycorrhizal (AM) colonisation and soil acidity (measured by pH and Al concentration) in order to evaluate the possibility that AM fungi facilitate the existence of plants on acidic soils. We sampled tussocks of four grass species, Elymus caninus, Poa nemoralis, Deschampsia cespitosa and Deschampsia flexuosa, together with samples of the surrounding soil, in oak forests of varying soil pH in southern Sweden. We determined pH, easily reacting Al (Al_r), extractable Al (Al_BaCl2) and phosphate in the soil samples, analysed the shoots for Al and phosphorous and quantified the degree of AM and fine endophyte (FE) colonisation in the roots. E. caninus was found on the least acidic soils and had the highest AM colonisation of all the species studied, while D. flexuosa, which was found on the most acidic soils, had the lowest AM colonisation. P. nemoralis and D. cespitosa were intermediate with respect to pH and AM colonisation. The colonisation of AM fungi exceeded FE colonisation for E. caninus and P. nemoralis, while the opposite was true for the two Deschampsia species. Our results indicated a negative relationship between Al_r and the degree of AM colonisation at the within-species level. The low colonisation of AM fungi on acidic soils may to some extent be explained by a sensitivity of AM fungi to Al_r: this parameter showed a stronger negative association with AM colonisation than did pH and Al_BaCl2. We hypothesize that Al toxicity is a critical factor for plant nutrition in forest soils through the impact on symbiotic fungi.     

Effects of human recombinant alpha-2b interferon and feline recombinant omega interferon on in vitro replication of feline herpesvirus-1

OBJECTIVE: To evaluate the effects of recombinant human interferon alpha-2b (rHuIFN-alpha2b) and recombinant feline interferon omega (rFeIFN-omega) on in vitro replication of feline herpesvirus (FHV)-1. SAMPLE POPULATION: Cultures of Crandell-Rees feline kidney (CRFK) cells. PROCEDURES: CRFK cells were treated with rFeIFN-omega or rHuIFN-alpha2b at concentrations ranging from 100 to 500,000 U/mL. Cultures were then inoculated with FHV-1. Constant concentrations of interferon products were maintained throughout the study. Reductions in the number and size of plaques were used as indicators of antiviral activity. Six plaque reduction assays were performed in duplicate. A 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay was used to detect cytotoxic effects of interferon. A 1-way ANOVA and Dunnett test were used to determine significant differences. RESULTS: Treatment with rFeIFN-omega at various concentrations resulted in significant reductions in the number of plaques (100,000 U/mL, 54.7%; and 500,000 U/mL, 59.8%) and in plaque size (100,000 U/mL, 47.5%; 250,000 U/mL, 81.0%; and 500,000 U/mL; 70.5%). Treatment with various concentrations of rHuIFN-alpha2b resulted in a significant reduction in plaque size (100,000 U/mL, 56.0%; 250,000 U/mL, 75.7%; and 500,000 U/mL, 69.0%). None of the tested concentrations of interferon caused significant cellular toxicosis. CONCLUSIONS AND CLINICAL RELEVANCE: At some of the higher concentrations, the antiviral effect of rFeIFN-omega was greater than the antiviral effect of rHuIFN-alpha2b. Reduction in plaque size appeared to be a good indicator of the antiviral activity of interferon against FHV-1.