Effects of area and isolation of woodland patches on herbaceous plant species richness across Great Britain

Richness of Ancient Woodland Indicator plant species was analysed in 308 woodland patches that were surveyed during the Countryside Survey of Great Britain carried out in 1998. The Countryside Survey recorded vegetation plots and landscape structure in 569 stratified 1 km sample squares and developed a remotely-sensed land cover map of the UK. Using these datasets, we tested the hypothesis that Ancient Woodland Indicator species richness in woodland fragments was limited by patch area, shape and spatial isolation and that woodland patches located in the lowland region of Great Britain would respond differently than those in the upland region. The variation in Ancient Woodland Indicator species richness in the British lowlands (n = 218) was mainly explained by patch area and two measures of connectivity, the length of hedgerows and lines of trees in the 1 km square and the area of woodland within 500 m of the vegetation plot. By contrast, variation in Ancient Woodland Indicator species richness in the British uplands (n = 90) was related to Ellenberg scores of the vegetation communities sampled – a surrogate for habitat quality – and no significant effect of spatial structure was detected. It therefore appears that the degree of fragmentation of woodland in the British lowlands limits the distribution of Ancient Woodland Indicator species, while in the uplands, failed colonisation is a matter of habitat quality rather than a result of landscape structure.This revised version was published online in May 2005 with corrections to the Cover Date.     

Long-term impacts of an organophosphate-based regime of pesticides on field and field-edge Collembola communities

During a 6-year study, effects of two contrasting regimes of pesticide use on pitfall and suction catches of Collembola were monitored in an arable field under a rotation of grass and winter wheat. Current farm practice (CFP) represented conventional fungicide and herbicide use plus applications of organophosphorus (OP) insecticides, whereas reduced input approach (RIA) utilised minimum inputs of fungicides and herbicides and excluded any use of insecticides. Compared with RIA, the CFP regime caused a substantial decline in the abundance and diversity of Collembola in the field, including the local disappearance of one species, without recovery during the study. At the field edge, which was protected during OP applications by a 6-m unsprayed buffer zone, effects of the CFP regime were less severe, and were not persistent in the long term. Some Collembola species occurred only in field-edge samples. Pitfall and suction sampling yielded remarkably similar patterns of catches, indicating that pitfall trapping may be appropriate for detecting long-term changes in collembolan abundance caused by intensive agricultural management practices.     

Meningoencephalitis in an adult cow due to Mortierella woifli.

A 7-year-old dairy cow presented with clinical signs of neurologic disease. Despite treatment with penicillin, the cow died 36 hours after initial presentation. Necropsy examination revealed multiple foci of hemorrhage within the cerebrum and thickened meninges. Additionally, endometritis and consolidation of approximately 30% of both lungs was observed. Histology revealed necrotizing vasculitis, infarction, and hemorrhage within sections of the brain, uterus, and lung. Large numbers of intralesional fungal hyphae were visible. Because only formalin-fixed tissue was available, polymerase chain reaction was used to make an etiologic diagnosis of Mortierella wolfii.     

Application and field validation of a PCR assay for the detection of Mycoplasma hyopneumoniae from swine lung tissue samples.

A PCR assay was validated for the detection of Mycoplasma hyopneumoniae in porcine lung tissue. The detection limit of the assay was 0.18 colony-forming units/g of lung sample spiked with M. hyopneumoniae. In field validation, 426 pigs from 220 cases were examined for M. hyopneumoniae infection by M. hyopneumoniae PCR and a fluorescent antibody (FA) test. In total, 103 pig lungs (24.2%) were positive in the PCR test, and 69 pig lungs (16.2%) were positive in the FA test, among which, 62 pigs were positive for both PCR and FA test. Most of the PCR-positive but FA test-negative cases had lesions compatible with M. hyopneumoniae infection. With Bayesian modeling, the diagnostic sensitivity and specificity of the PCR were determined to be 97.3% and 93.0%, respectively.     

Effects of dietary astaxanthin concentration and feeding period on the skin pigmentation of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

A single‐factor experiment was conducted to investigate the effects of dietary astaxanthin concentration on the skin colour of snapper. Snapper (mean weight=129 g) were held in white cages and fed one of seven dietary levels of unesterified astaxanthin (0, 13, 26, 39, 52, 65 or 78 mg astaxanthin kg^?1) for 63 days. Treatments comprised four replicate cages, each containing five fish. The skin colour of all fish was quantified using the CIE L^*, a^*, b^* colour scale after 21, 42 and 63 days. In addition, total carotenoid concentrations of the skin of two fish cage^?1 were determined after 63 days. Supplementing diets with astaxanthin strongly affected redness (a^*) and yellowness (b^*) values of the skin at all sampling times. After 21 days, the a^* values increased linearly as the dietary astaxanthin concentration was increased before a plateau was attained between 39 and 78 mg kg^?1. The b^* values similarly increased above basal levels in all astaxanthin diets. By 42 days, a^* and b^* values increased in magnitude while a plateau remained between 39 and 78 mg kg^?1. After 63 days, there were no further increases in measured colour values, suggesting that maximum pigmentation was imparted in the skin of snapper fed diets >39 mg kg^?1 after 42 days. Similarly, there were no differences in total carotenoid concentrations of the skin of snapper fed diets >39 mg kg^?1 after 63 days. The plateaus that occurred in a^* and b^* values, while still increasing in magnitude between 21 and 42 days, indicate that the rate of astaxanthin deposition in snapper is limited and astaxanthin in diets containing >39 mg astaxanthin kg^?1 is not efficiently utilized. Astaxanthin retention after 63 days was greatest from the 13 mg kg^?1 diet; however, skin pigmentation was not adequate. An astaxanthin concentration of 39 mg kg^?1 provided the second greatest retention in the skin while obtaining maximum pigmentation. To efficiently maximize skin pigmentation, snapper growers should commence feeding diets containing a minimum of 39 mg unesterified astaxanthin kg^?1 at least 42 days before sale.     

Stomatal conductance of Acer rubrum ecotypes under varying soil and atmospheric water conditions: predicting stomatal responses with an abscisic acid-based model

A multiplicative model of stomatal conductance was developed and tested in two functionally distinct ecotypes of Acer rubrum L. (red maple). The model overcomes the main limitation of the commonly used Ball-Berry model (Ball et al. 1987) by accounting for stomatal behavior under soil drying conditions. We combined the Ball-Berry model with an integrated expression of abscisic acid (ABA)-based stomatal response to ABA concentration ([ABA]) in bulk leaf tissue (gfac), which coupled physiological changes at the leaf level with those in the root. The factor gfac = exp(-beta[ABA]L) incorporated the stomatal response to [ABA] into the Ball-Berry model by down regulating stomatal conductance (gs) in response to physiological changes in the root. The down regulation of gs is pertinent under conditions where soil drying may modify the delivery of chemical signals to leaf stomata. Model testing indicated that the multiplicative model was capable of predicting gs in red maple under wide ranges of soil and atmospheric conditions. Concordance correlation coefficients were high (between 0.59 and 0.94) for the tested ecotypes under three environmental conditions (atmospheric, rhizospheric and minimal stress). The study supported the use of gfac as a gas exchange function that controls water stress effects on gs and aids in the prediction of gs responses.     

Growth performance and management of a mixed rainforest tree plantation

Monoculture plantations of Pinus, Eucalyptus and Acacia have beenestablished on rainforest lands throughout the world. However, this type of reforestation generally supplies low quality timber and contributes to landscape simplification. Alternatives to exotic monoculture plantations are now beginning to gain momentum with farmers and landholders attempting to establish a variety of rainforest trees in small plantations. When compared to the well studied commercial species, knowledge concerning the growth and management of many of these rainforest species is in its infancy. To help expand this limited knowledge base an experimental plantation of 16 rainforest tree species in a randomised design was established near Mt. Mee, in south-eastern Queensland, Australia. Changes in growth, form (based on stem straightness, branch size and branchiness), crown diameters and leaf area of each species were examined over 5 years. Patterns of height growth were also measured monthly for 31 months. Species in this trial could be separated into three groups based on their overall growth after 5 years and their growth patterns. Early successional status, low timber density, high maximum photosynthetic rates and large total leaf areas were generally correlated to rapid height growth. Several species (including Araucaria cunninghamii, Elaeocarpus grandis, Flindersia brayleyana, Grevillea robusta and Khaya nyasica) had above average form and growth, while all species in the trial had considerable potential to have increased productivity through tree selection. As canopy closure occurred at the site between years four and five, growth increments declined. To reduce stand competition a number of different thinning techniques could be employed. However, simple geometric or productivity based thinnings appear to be inappropriate management techniques for this mixed species stand as they would either remove many of the best performing trees or nearly half the species in the trial. Alternatively, a form based thinning would maintain the sites diversity, increase the average form of the plantation and provide some productivity benefits.     

Effects of extrusion processing on digestibility of peas, lupins, canola meal and soybean meal in silver perch Bidyanus bidyanus (Mitchell) diets

Two experiments were conducted to investigate effects of processing on apparent digestibility coefficients (ADCs) of legumes and oilseeds for juvenile silver perch, Bidyanus bidyanus (～49 g). The first experiment evaluated interactive effects of ingredients (lupins or field peas), processing (whole seed; hulls on or hulls off) and extrusion cooking (raw or extruded) on ADCs for juvenile silver perch (～4 g fish^?1). The second experiment was a three‐fixed‐factor anova designed to evaluate interactive effects of ingredients (soybean meal or canola meal), extrusion cooking (raw or extruded) and inclusion content (30% or 50% of the diet) on ADCs for juvenile silver perch (～4 g fish^?1). Lupin protein was more digestible than that of peas (ADC for crude protein 91% vs. 85% for peas) but the organic matter was less digestible (ADC for organic matter 50% vs. 67% for peas). Dehulling lupins significantly improved ADCs for all indices (dry matter, organic matter, energy and crude protein), but extrusion had no effect because lupins do not contain starch or heat‐labile anti‐nutrients. Conversely, for starch‐rich peas that contain heat‐labile trypsin inhibitors, both dehulling and extrusion significantly improved ADCs. Digestibility of soybean meal was much higher than that of canola meal. For soybean meal, neither processing, content nor their interaction affected digestibility but extrusion improved ADCs for dry matter, organic matter and energy but there was an interaction with content. Although higher overall, digestibility for these indices declined with increasing content for extruded product while there were only minor effects of inclusion for raw product. Benefits of extrusion were attributed to reductions in anti‐nutrients, including phytic acid. For canola, there were no interactions between extrusion and content for any ADC. Increasing content reduced ADCs for crude protein, dry matter and organic matter but did not effect energy. Surprisingly, extrusion of canola also reduced digestibility for all ADCs. Dehulling improved both lupins and peas. Crude protein for all ingredients was well digested with ingredients ranked: lupins>soybean meal>peas>canola meal. Energy digestibility was best for soybean meal and worst for lupins. Extrusion greatly improved digestibility of peas and to a lesser extent soybean meal, gave no benefits to lupins and was detrimental for canola.     

Leaf physiology and morphology of Castanea dentata (Marsh.) Borkh., Castanea mollissima Blume,and three backcross breeding generations planted in the southern Appalachians,USA

Backcross breeding programs have been used to transfer disease resistance and other traits from one forest tree species to another in order to meet restoration objectives. Evaluating the field performance of such material is critical for determining the success of breeding programs. In eastern North America, The American Chestnut Foundation has a backcross breeding program that uses Chinese chestnut (Castanea mollissima Blume) to introduce resistance of the fungal pathogen chestnut blight [Cryphonectria parasitica (Murr.) Barr.] to the native American chestnut [Castanea dentata (Marsh.) Borkh.]. We compared physiological and morphological characteristics among seedlings of American chestnut, Chinese chestnut, and BC₁F₃, BC₂F₃, and BC₃F₃ hybrid chestnuts during their fourth growing season after field-planting. American chestnut and the BC₃F₃ breeding generation displayed photosynthetic light-response curves that were similar to each other but different from Chinese chestnut. Rates of photosynthesis were higher for American chestnut and the BC₃F₃ breeding generation when compared to Chinese chestnut for light levels ≥800 μmol m^?2 s^?1 photosynthetic photon flux density and for maximum photosynthetic capacity. Leaf morphology variables were not different between American chestnut and any of the breeding generations, but leaf area (on a per leaf basis) of Chinese chestnut was lower than that of any other chestnut type. Our results suggest that backcross breeding can be used to transfer desirable traits for restoration of native species threatened by non-native pathogens.