18 research outputs found

    Recent Shift in Climate Relationship Enables Prediction of the Timing of Bird Breeding

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    Large-scale climate processes influence many aspects of ecology including breeding phenology, reproductive success and survival across a wide range of taxa. Some effects are direct, for example, in temperate-zone birds, ambient temperature is an important cue enabling breeding effort to coincide with maximum food availability, and earlier breeding in response to warmer springs has been documented in many species. In other cases, time-lags of up to several years in ecological responses have been reported, with effects mediated through biotic mechanisms such as growth rates or abundance of food supplies. Here we use 23 years of data for a temperate woodland bird species, the great tit (Parus major), breeding in deciduous woodland in eastern England to demonstrate a time-lagged linear relationship between the on-set of egg laying and the winter index of the North Atlantic Oscillation such that timing can be predicted from the winter index for the previous year. Thus the timing of bird breeding (and, by inference, the timing of spring events in general) can be predicted one year in advance. We also show that the relationship with the winter index appears to arise through an abiotic time-lag with local spring warmth in our study area. Examining this link between local conditions and larger-scale processes in the longer-term showed that, in the past, significant relationships with the immediately preceding winter index were more common than those with the time-lagged index, and especially so from the late 1930s to the early 1970s. However, from the mid 1970s onwards, the time-lagged relationship has become the most significant, suggesting a recent change in climate patterns. The strength of the current time-lagged relationship suggests that it might have relevance for other temperature-dependent ecological relationships

    Integrating soil quality changes to arable agricultural systems following organic matter addition, or adoption of a ley-arable rotation

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    To study the sustainability of arable agricultural systems we examined a wide range of biological, physical and chemical properties associated with changes in soil quality. We integrated these using a qualitative multi-attribute model supported by the software tool DEXi to achieve a holistic estimation of soil quality. We tested the relative changes in soil quality attributes resulting from the incorporation of cattle slurry or green-waste compost, or from including a ley phase in the production of arable crops. We measured: abundances and biodiversity of the soil biota, physical properties and nutrient concentrations; twice in 2006 and thrice in 2007. These data were used to generate a model of soil quality, which showed that the addition of organic matter or a ley phase did increase soil quality. However, to fully understand the soil system results should be derived from a number of functionally related observations as there were opposing trends in individual observations. Increases in some beneficial attributes (such as decomposition, soil nutrient status and physical condition) were associated with an increased risk of nutrient losses from leaching and gaseous emissions. Assessing soil quality with only a few indicators may not identify these trade-offs. The multi-attribute modelling approach could identify the pathways responsible for changes in soil quality and identify possible environmentally detrimental effects
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