Cleaning sky survey databases using Hough Transform and Renewal String approaches

Large astronomical databases obtained from sky surveys such as the SuperCOSMOS Sky Survey (SSS) invariably suffer from spurious records coming from artefactual effects of the telescope, satellites and junk objects in orbit around earth and physical defects on the photographic plate or CCD. Though relatively small in number these spurious records present a significant problem in many situations where they can become a large proportion of the records potentially of interest to a given astronomer. Accurate and robust techniques are needed for locating and flagging such spurious objects, and we are undertaking a programme investigating the use of machine learning techniques in this context. In this paper we focus on the four most common causes of unwanted records in the SSS: satellite or aeroplane tracks, scratches, fibres and other linear phenomena introduced to the plate, circular halos around bright stars due to internal reflections within the telescope and diffraction spikes near to bright stars. Appropriate techniques are developed for the detection of each of these. The methods are applied to the SSS data to develop a dataset of spurious object detections, along with confidence measures, which can allow these unwanted data to be removed from consideration. These methods are general and can be adapted to other astronomical survey data.Comment: Accepted for MNRAS. 17 pages, latex2e, uses mn2e.bst, mn2e.cls, md706.bbl, shortbold.sty (all included). All figures included here as low resolution jpegs. A version of this paper including the figures can be downloaded from http://www.anc.ed.ac.uk/~amos/publications.html and more details on this project can be found at http://www.anc.ed.ac.uk/~amos/sattrackres.htm

Population responses to observed climate variability across multiple organismal groups

A major challenge in ecology is to understand how populations are affected by increased climate variability. Here, we assessed the effects of observed climate variability on different organismal groups (amphibians, insects, mammals, herbaceous plants and reptiles) by estimating the extent to which interannual variation in the annual population growth rates (CVλ) and the absolute value of the long-term population growth rate (|log λ|) were associated with short-term climate variability. We used empirical data (≥ 20 consecutive years of annual abundances) from 59 wild populations in the Northern Hemisphere, and quantified variabilities in population growth rates and climatic conditions (temperature and precipitation in active and inactive seasons) calculated over four- and eight-year sliding time windows. We observed a positive relationship between the variability of growth rate (CVλ) and the variability of temperature in the active season at the shorter timescale only. Moreover, |log λ| was positively associated with the variability of precipitation in the inactive season at both timescales. Otherwise, the direction of the relationships between population dynamics and climate variability (if any) depended largely on the season and organismal group in question. Both CVλ and |log λ| correlated negatively with species’ lifespan, indicating general differences in population dynamics between short-lived and long-lived species that were not related to climate variability. Our results suggest that although temporal variation in population growth rates and the magnitude of long-term population growth rates are partially associated with short-term interannual climate variability, demographic responses to climate fluctuations might still be population-specific rather than specific to given organismal groups, and driven by other factors than the observed climate variability

An Integrated Weed Management framework: A pan-European perspective

Initiatives to reduce the reliance of agriculture on pesticides, including the European Union (EU) Directive 2009/ 128/EC on the sustainable use of pesticides (SUD), have yet to lead to widespread implementation of Integrated Pest Management (IPM) principles. Developments in weed management have strongly focused on increasing the efficiency of herbicides or substituting herbicides with other single tactics such as mechanical control. To in- crease sustainability of agricultural systems in practice, a paradigm shift in weed management is needed: from a single tactic and single growing season approach towards holistic integrated weed management (IWM) consid- ering more than a single cropping season and focusing on management of weed communities, rather than on control of single species. To support this transition, an IWM framework for implementing a system level approach is presented. The framework consists of five pillars: diverse cropping systems, cultivar choice and establishment, field and soil management, direct control and the cross-cutting pillar monitoring and evaluation. IWM is an integral part of integrated pest management (IPM) and adopting IWM will serve as a driver for the development of sustainable agricultural systems of the futur

Engineering a plant community to deliver multiple ecosystem services

The sustainable delivery of multiple ecosystem services requires the management of functionally diverse biological communities. In an agricultural context, an emphasis on food production has often led to a loss of biodiversity to the detriment of other ecosystem services such as the maintenance of soil health and pest regulation. In scenarios where multiple species can be grown together, it may be possible to better balance environmental and agronomic services through the targeted selection of companion species. We used the case study of legume-based cover crops to engineer a plant community that delivered the optimal balance of six ecosystem services: early productivity, regrowth following mowing, weed suppression, support of invertebrates, soil fertility building (measured as yield of following crop), and conservation of nutrients in the soil. An experimental species pool of 12 cultivated legume species was screened for a range of functional traits and ecosystem services at five sites across a geographical gradient in the United Kingdom. All possible species combinations were then analyzed, using a process-based model of plant competition, to identify the community that delivered the best balance of services at each site. In our system, low to intermediate levels of species richness (one to four species) that exploited functional contrasts in growth habit and phenology were identified as being optimal. The optimal solution was determined largely by the number of species and functional diversity represented by the starting species pool, emphasizing the importance of the initial selection of species for the screening experiments. The approach of using relationships between functional traits and ecosystem services to design multifunctional biological communities has the potential to inform the design of agricultural systems that better balance agronomic and environmental services and meet the current objective of European agricultural policy to maintain viable food production in the context of the sustainable management of natural resources

Quantifying farm sustainability through the lens of ecological theory

The achievements of the Green Revolution in meeting the nutritional needs of a growing global population have been won at the expense of unintended consequences for the environment. Some of these negative impacts are now threatening the sustainability of food production through the loss of pollinators and natural enemies of crop pests, the evolution of pesticide resistance, declining soil health and vulnerability to climate change. In the search for farming systems that are sustainable both agronomically and environmentally, alternative approaches have been proposed variously called ‘agroecological’, ‘conservation agriculture’, ‘regenerative’ and ‘sustainable intensification’. While the widespread recognition of the need for more sustainable farming is to be welcomed, this has created etymological confusion that has the potential to become a barrier to transformation. There is a need, therefore, for objective criteria to evaluate alternative farming systems and to quantify farm sustainability against multiple outcomes. To help meet this challenge, we reviewed the ecological theories that explain variance in regulating and supporting ecosystem services delivered by biological communities in farmland to identify guiding principles for management change. For each theory, we identified associated system metrics that could be used as proxies for agroecosystem function. We identified five principles derived from ecological theory: (i) provide key habitats for ecosystem service providers; (ii) increase crop and non-crop habitat diversity; (iii) increase edge density: (iv) increase nutrient-use efficiency; and (v) avoid extremes of disturbance. By making published knowledge the foundation of the choice of associated metrics, our aim was to establish a broad consensus for their use in sustainability assessment frameworks. Further analysis of their association with farm-scale data on biological communities and/or ecosystem service delivery would provide additional validation for their selection and support for the underpinning theories

Agricultural fertilisers contribute substantially to microplastic concentrations in UK soils

Since their invention, plastics have driven a revolution in behavior in all aspects of our lives, including agriculture. In-use and as a waste material, plastics degrade and accumulate in agricultural systems. Accumulation of plastic pollution in agricultural systems has negative impacts on human health and agricultural productivity but little is known about concentrations of microplastics in soils. Here we used a historical time series to examine changes to microplastic concentrations in agricultural soils over time. Microplastics were stained with Nile Red and quantified using fluorescence microscopy. We demonstrate that microplastic concentrations increased at higher rates in soils that are amended with either organic or inorganic fertiliser between 1966 and 2022, suggesting that agricultural fertilisers are an important contributor to microplastic concentrations in agricultural soils over time. This study provides evidence that agricultural soils are receptors and reservoirs of microplastic pollution, a legacy which is growing over time

Using legume-based mixtures to enhance the nitrogen use efficiency and economic viability of cropping systems - Final report (LK09106/HGCA3447)

As costs for mineral fertilisers rise, legume-based leys are recognised as a potential alternative nitrogen source for crops. Here we demonstrate that including species-rich legume-based leys in rotations helps to maximise synergies between agricultural productivity and other ecosystem services. By using functionally diverse plant species mixtures, these services can be optimised and fine-tuned to regional and farm-specific needs. Replicated field experiments were conducted over three years at multiple locations, testing the performance of 12 legume species and 4 grass species sown in monocultures, as well as in a mixture of 10 of the legumes and all 4 grasses (called the All Species Mix, ASM). In addition, we compared this complex mixture to farmer-chosen ley mixtures on 34 sites across the UK. The trials showed that there is a large degree of functional complementarity among the legume species. No single species scored high on all evaluation criteria. In particular, the currently most frequently used species, white clover, is outscored by other legume species on a number of parameters such as early development and resistance to decomposition. Further complementarity emerged from the different responses of legume species to environmental variables, with soil pH and grazing or cutting regime being among the more important factors. For example, while large birdsfoot trefoil showed better performance on more acidic soils, the opposite was true for sainfoin, lucerne and black medic. In comparison with the monocultures, the ASM showed increased ground cover, increased above-ground biomass and reduced weed biomass. Benefits of mixing species with regard to productivity increased over time. In addition, the stability of biomass production across sites was greater in the ASM than in the legume monocultures. Within the on-farm trials, we further found that on soils low in organic matter the biomass advantage of the ASM over the Control ley was more marked than on the soils with higher organic matter content. Ecological modelling revealed that the three best multifunctional mixtures all contained black medic, lucerne and red clover. Within the long term New Farming Systems (NFS) rotational study, the use of a clover bi-crop showed improvement to soil characteristics compared to current practice (e.g. bulk density and water infiltration rate). Improvements in wheat yield were also noted with respect to the inclusion of a clover bi-crop in 2010, but there was evidence of a decline in response as the N dose was increased. Cumulatively, over both the wheat crop and the spring oilseed rape crop, the clover bi-crop improved margin over N. The highest average yield response (~9%) was associated with the ASM legume species mix cover cropping approach

The Mineral Composition of Wild Type and Cultivated Varieties of Pasture Species

Mineral deficiencies in livestock are often prevented by using prophylactic supplementation, which is imprecise and inefficient. Instead, the trend for increased species diversity in swards is an opportunity to improve mineral concentrations in the basal diet. Currently there are limited data on the mineral concentrations of different species and botanical groups, particularly for I and Se, which are among the most deficient minerals in livestock diets. We grew 21 pasture species, including some cultivar/wild type comparisons, of grasses, legumes and forbs, as single species stands in a pot study in a standard growth medium. Herbage concentrations of Co, Cu, I, Mn, Se, Zn, S, Mo and Fe showed no consistent differences between the wild and cultivated types. There were significant differences between botanical groups for many minerals tested. Forbs were highest in I and Se, grasses in Mn, and legumes in Cu, Co, Zn and Fe. Comparing species concentrations to recommended livestock intakes, the forbs Achillea millefolium, Cichorium intybus and Plantago lanceolate, and the legumes Medicago lupulina, Trifolium hybridum, and Lotus corniculatus, appear good sources of Co, Cu, I, Se and Zn. Further work is required to ensure these results are consistent in multispecies mixtures, in different soil types, and in field trials

Predicting intercrop competition, facilitation, and productivity from simple functional traits

Open Access ArticleContext Recent meta-analyses demonstrate that intercropping can increase the land use efficiency of crop production by 20–30 % on average, indicating a strong potential contribution to sustainable intensification. However, there is substantial variability around this average: individual studies range from half to double the land productivity of monocrops. Legume-cereal intercrops and intercrops with high temporal niche separation tend to be more productive than the average, but these two combination types are not always suitable. There is a need to explore other possibilities to achieve productive intercrops. Research question We explored whether two simple functional traits involved in radiation use, plant vegetative height and specific leaf area (SLA), could be used to predict intercrop productivity. Height and SLA together are associated with key plant life-history and resource economy strategies determining competitiveness and tolerance of competition, especially with regard to light, and could therefore be expected to underpin overyielding in intercrops. Methods In the first year of our study, we grew crops as monocrops at one site in Kenya and measured their height and SLA. In the second year, we grew crops in monocrop, intercrop, and single plant treatments at two sites in Kenya and one site in Nigeria. Together, these treatments allowed us to identify whether each intercrop combination overyielded or underyielded, and whether any overyielding was driven by facilitation and/or differences in inter- vs intraspecific competition. We then related the strength of these interactions to the two traits. Results We found that intercrop grain yields varied in relation to the height and SLA of each species in the intercrop, but together these traits explained less than a third of variation in intercrop land equivalence ratios (LER). More variation could be explained by allowing for the effect of site, suggesting that the two traits interact with site conditions to determine yield. Biomass LERs responded differently to grain LERs, suggesting that plasticity in resource allocation in response to intercropping conditions may further influence yields. Conclusions Our study found some evidence that combining species with traits indicating contrasting responses to competition (an avoidant species with a tolerant species) could increase resource use complementarity and thus intercrop overyielding. However, it was clear that other factors (such as additional traits, or the trait by site interaction) are needed to refine our understanding of intercrop productivity. Implications A trait-based framework has potential to predict intercrop productivity, but simple measures of height and SLA alone are insufficient

Renewal Strings for Cleaning Astronomical Databases

Large astronomical databases obtained from sky surveys such as the SuperCOSMOS Sky Surveys (SSS) invariably suffer from a small number of spurious records coming from artefactual effects of the telescope, satellites and junk objects in orbit around earth and physical defects on the photographic plate or CCD. Though relatively small in number these spurious records present a significant problem in many situations where they can become a large proportion of the records potentially of interest to a given astronomer. In this paper we focus on the four most common causes of unwanted records in the SSS: satellite or aeroplane tracks, scratches fibres and other linear phenomena introduced to the plate, circular halos around bright stars due to internal reflections within the telescope and diffraction spikes near to bright stars. Accurate and robust techniques are needed for locating and flagging such spurious objects. We have developed renewal strings, a probabilistic technique combining the Hough transform, renewal processes and hidden Markov models which have proven highly effective in this context. The methods are applied to the SSS data to develop a dataset of spurious object detections, along with confidence measures, which can allow this unwanted data to be removed from consideration. These methods are general and can be adapted to any future astronomical survey data.Comment: Appears in Proceedings of the Nineteenth Conference on Uncertainty in Artificial Intelligence (UAI2003