Modelling bird distributions — a combined GIS and bayesian rule-based approach

Models to predict the breeding distribution of three species of birds in north-east England are described. The models use readily available data from the ornithological literature on the habitat preferences and life-history characteristics of the birds, together with satellite (land cover) and physiographic data. These data are linked via Bayesian decision-rules, and model predictions calculated at the landscape scale using a raster-based geographic Information System. Log-linear regressions of the predicted suitability of the landscape for the birds with observed sets of nest records were statistically significant for all three species. The robustness of the models to the effects of nonindependence of predictor (habitat) variables on Bayesian predictions was investigated using a perturbation method, which gave minor improvements to the accuracy of the predictions. The value of this modelling approach as a method of utilising published autoecological data to predict the landscape distribution of birds is discussed.     

Cosmic ray and solar particle investigations over the South polar regions of the sun

Observations of galactic cosmic radiation and anomalous component nuclei with charged particle sensors on the Ulysses spacecraft showed that heliospheric magnetic field structure over the south solar pole does not permit substantially more direct access to the local interstellar cosmic ray spectrum than is possible in the equatorial zone. Fluxes of galactic cosmic rays and the anomalous component increased as a result of latitude gradients by less than 50% from the equator to -80 degrees . Thus, the modulated cosmic ray nucleon, electron, and anomalous component fluxes are nearly spherically symmetric in the inner solar system. The cosmic rays and the anomalous nuclear component underwent a continuous, -26 day recurrent modulation to -80.2 degrees , whereas all recurring magnetic field compressions and recurring streams in the solar wind disappeared above approximately 55 degrees S latitude.     

Lead pica produced in rats

Weanling rats eating a low calcium diet voluntarily ingested lead acetate solutions in much greater proportions than did iron-deficient or control weanlings. This increased ingestion occurred even with high concentrations of lead acetate which normal weanlings found extremely aversive. Chronic injections of lead acetate into weanlings did not change lead ingestion, indicating an absence of behavioral regulation of body lead levels. Female lead-injected weanlings did show a significant increase in calcium ingestion. Calcium deficiency may be one component of lead pica.     

Effect of seedpiece spacing and nitrogen fertilization on tuber yield, yield components, and nitrogen use efficiency parameters of two potato cultivars

The effect of seedpiece spacing on the efficiency of nitrogen (N) use by the potato crop is generally unknown. The objective of this experiment was to determine the effect of seedpiece spacing on tuber yield, yield components and N use efficiency parameters of two potato cultivars. Potato cultivars Atlantic and Shepody were grown at two rates of N fertilization (0 or 100 kg N ha^?1) and three seedpiece spacings (20, 30, or 40 cm) in 2000 to 2002. Wider seedpiece spacing increased mean tuber weight and the number of tubers per stem, but decreased total tuber yield. The higher tuber yield at the narrow seedpiece spacing was attributed to higher biomass production in combination with lower tuber specific gravity. Seedpiece spacing had no consistent effect on plant N accumulation, and therefore no consistent effect on N uptake efficiency (plant N accumulation /N supply from the soil plus fertilizer). However, a small increase in soil NO₃-N concentration in the hill at topkill at wider seedpiece spacing suggested plant N accumulation was slightly reduced at wider seedpiece spacing, but at a level that could not be detected from a plant-based measure of N accumulation. The reduced dry matter accumulation, but similar plant N accumulation, resulted in lower N use efficiency (plant dry matter accumulation / N supply) at wider seedpiece spacing. Wider seedpiece spacing also resulted in generally lower values of N utilization efficiency (plant dry matter accumulation / plant N accumulation) for the 40-cm compared with the 20- and 30-cm seedpiece spacings. Effects of seedpiece spacing on N use efficiency parameters were generally consistent across cultivars and fertilizer N rates. Wider seedpiece spacing did reduce the efficiency of N use by the potato crop; however, the magnitude of the effect was small under the conditions of this study.     

The effect of copper applications on the movement of copper and other elements in organic soils

Copper concentrations should be maintained at 100 ppm (gg Cu g^?1 dry soil) in the surface layers of undecomposed peat soils, and 400 ppm in humified muck soils. The Cu supports plant nutrition, and inhibits enzymes that degrade the organic soils (Histosols). The required or extravagant applications of Cu may threaten groundwater quality if the Cu, or elements displaced by the Cu, moves downwards in the soils. To test this, powdered CUSO₄.5H₂O was applied to the top 15 cm of replicated microplots of organic soils to increase their Cu concentrations by 0, 150, 500, and 1500 ppm at field sites A (peat) and B (muck) in May 1978 and by 0, 100, 300, and 800 ppm at field site C (mucky peat) in 1979. Duplicate cores of up to 50 cm depth were taken in the spring of 1981 from each of the 56 microplots and analyzed. At all sites, none of the Cu additions caused significant displacement and downward movement of Ca, Mg, K, Fe, Mn, or Zn. There was a leaching of small fractions of the applied Cu down to 40 cm depth only when 1500 ppm of Cu was added to the humus-poor, acidic peat at site A. Some of the Cu applied at the 500 ppm rate at site A and 1500 ppm rate at site B was found in the 20 to 30 cm zone. At site C, none of the applied Cu moved from the top 20 cm (plow layer).     

Effect of sulfur,calcium, and boron on tissue nutrient concentration and potato yield 1

Field studies were conducted over three years on Podzol soils in Prince Edward Island (P.E.I.) on the effect of sulfur (S), calcium (Ca), and boron (B) fertilization on tissue nutrient concentration and potato yield. Leaf tissues were sampled at 10% bloom and again two weeks later for S, Ca, and B analysis. In the absence of S fertilization, S deficiency symptoms, as evidenced by lighter green foliage were found. The mean tuber yield response due to S addition was 1.1 (SE = 0.40) t/ha. Addition of S either as gypsum or magnesium sulfate was effective in overcoming the S deficiency symptoms and in increasing the S concentration in the leaves. Calcium and B additions did not affect the tuber yields. While Ca applications were ineffective in increasing the Ca concentration in the leaf tissue, B applications significantly increased the leaf tissue B concentration in both samplings. The interaction effects between S, Ca, and B were not significant on any of the components tested. Data indicated that 0.25 to 0.27 and 0.28 to 0.32% S in potato leaves were in the S deficiency and sufficiency range, respectively. This is the first documented case of S deficiency in the field in P.E.I. Potatoes and possibly other crops should be monitored for S‐deficiency symptoms and S levels in plant tissues should be recorded to detect any trends.     

Temperature and Precipitation Affect Steer Weight Gains Differentially by Stocking Rate in Northern Mixed-Grass Prairie

Cattle weight gain responses to seasonal weather variability are difficult to predict for rangelands because few long-term (>20 yr) studies have been conducted. However, an increased understanding of temperature and precipitation influences on cattle weight gains is needed to optimize stocking rates and reduce enterprise risk associated with climatic variability. Yearling steer weight gain data collected at the USDA-ARS High Plains Grasslands Research Station at light, moderate, and heavy stocking rates for 30 years (1982–2011) were used to examine the effects of spring (April–June) and summer (July–September) temperature and precipitation, as well as prior-growing-season (prior April–September) and fall/winter (October–March) precipitation, on beef production (kg · ha^?1). At heavier stocking rates, steer production was more sensitive to seasonal weather variations. A novel finding was that temperature (relatively cool springs and warm summers) played a large predictive role on beef production. At heavier stocking rates, beef production was highest during years with cool, wet springs and warm, wet summers, corresponding to optimum growth conditions for this mixed C₃–C₄ plant community. The novelty and utility of these findings may increase the efficacy of stocking rate decision support tools. The parsimonious model structure presented here includes three-month seasonal clusters that are forecasted and freely available from the US National Oceanic and Atmospheric Administration up to a year in advance. These seasonal weather forecasts can provide ranchers with an increased predictive capacity to adjust stocking rates (in advance of the grazing season) according to predicted seasonal weather conditions, thereby reducing enterprise risk.     

Weed control practices on Costa Rican coffee farms: is herbicide use necessary for small-scale producers?

This paper presents research conducted during two coffee farming seasons in Costa Rica. The study examined coffee farmers?? weed management practices and is presented in the form of a case study of small-scale farmers?? use of labor and herbicides in weed management practices. Over 200 structured interviews were conducted with coffee farmers concerning their use of hired labor and family labor, weed management activities, support services, and expectations about the future of their coffee production. ANOVA and regression analyses describe the relationships between farm size, labor, and herbicide use, and three farm types (i.e., conventional, semi-conventional, and organic). Based on findings regarding the amount of labor used to manually control weeds on different types of farms (large farms, small conventional, semi-conventional, and organic farms) I am able to challenge small conventional farmers?? perceived need for herbicide use. Semi-structured interviews of coffee farmers and extension workers further revealed a dominant role played by agro-chemical companies in assisting farmers with production problems, and documented a high transaction cost for information provided from elsewhere. Chemical companies hire extension workers to visit farmers at their farms, free of charge, to offer recommendations on how to treat different pest problems, while government and cooperative extension agents charge for the service. There is a need to increase the amount of resources available to the National Coffee Institute to fund one-on-one farmer support services in order to balance the influence of agro-chemical company representatives and allow farmers to make better decisions regarding weed management.     

Empirical move‐on rules to inform fishing strategies: a New England case study

Increasingly, fisheries are being managed under catch quotas that are often further allocated to specific permit holders or sectors. At the same time, serious consideration is being given to the effects of discards on the health of target and non‐target species. Some quota systems have incorporated discard reduction as an objective by counting discards (including unmarketable fish) against the overall quota. The potential effect of the introduction of a quota system that includes accountability for discards on the fishing strategies employed by fishermen is enormous. This is particularly true for multispecies fisheries where healthy and depleted stocks co‐exist; resulting in a trip's catch being applied to very large and very small stock quotas simultaneously. Under such a scenario, fishermen have a strong incentive to minimize (i) catch of low‐quota or ‘choke’ stocks, (ii) regulatory discards due to minimum size limits and (iii) catch partially consumed by predators. ‘Move‐on’ rules (i.e. event‐triggered, targeted, temporary closure of part of a fishery when a catch or bycatch threshold is reached) have been employed in a variety of fisheries. However, their efficacy has been limited by a lack of empirical analyses underpinning the rules. Here, we examine the utility of spatiotemporal autocorrelation analyses to inform ‘move‐on’ rules to assist a sector of the New England Multispecies Fishery to reduce discards and maximize profits. We find the use of empirical move‐on rules could reduce catch of juvenile and choke stocks between 27 and 33%, and depredation events between 41 and 54%.