Spatial structure effects on the detection of patches boundaries using local operators

Landscapes exhibit various degrees of spatial heterogeneity according to the differential intensity and interactions among processes and disturbances that they are subjected to. The management of these spatially dynamical landscapes requires that we can accurately map them and monitor the evolution of their spatial arrangement through time. Such a mapping requires first the delineation of various spatial features present in the landscape such as patches and their boundaries. However, there are several environmental (spatial variability) as well as technical (spatial resolution) factors that impair our ability to accurately delineate patches and their boundaries as polygons. Here, we investigate how the spatial structure and spatial resolution of the data affect the accuracy of detecting patches and their boundaries over simulated landscapes and real data. Simulated landscapes consisted of two patches with parameterized spatial properties (patches’ level of spatial autocorrelation, mean value and variance) separated by a boundary of known location. Real data allowed the investigation of a more complex landscape where there is a known transition between two forest domains with unknown spatial properties. Boundary locations are defined using the lattice-wombling edge detector at various aggregation levels and the degree of patch homogeneity is determined using Getis-Ord’s G*. Results show that boundary detection using a local edge detector is greatly affected by the spatial conditions of the data, namely variance, abruptness of the spatial gradient between two patches and patches’ level of spatial autocorrelation. They also suggest that data aggregation is not a panacea for bringing out the ecological process creating the patches and that indicators derived from local measures of spatial association can be complementary tools for analysing spatial structures affecting boundary delineation.

Quantifying and mapping species threat abatement opportunities to support national target setting

The successful implementation of the Convention on Biological Diversity's post-2020 Global Biodiversity Framework will rely on effective translation of targets from global to national level and increased engagement across diverse sectors of society. Species conservation targets require policy support measures that can be applied to a diversity of taxonomic groups, that link action targets to outcome goals, and that can be applied to both global and national data sets to account for national context, which the species threat abatement and restoration (STAR) metric does. To test the flexibility of STAR, we applied the metric to vascular plants listed on national red lists of Brazil, Norway, and South Africa. The STAR metric uses data on species’ extinction risk, distributions, and threats, which we obtained from national red lists to quantify the contribution that threat abatement and habitat restoration activities could make to reducing species’ extinction risk. Across all 3 countries, the greatest opportunity for reducing plant species’ extinction risk was from abating threats from agricultural activities, which could reduce species’ extinction risk by 54% in Norway, 36% in South Africa, and 29% in Brazil. Species extinction risk could be reduced by a further 21% in South Africa by abating threats from invasive species and by 21% in Brazil by abating threats from urban expansion. Even with different approaches to red-listing among countries, the STAR metric yielded informative results that identified where the greatest conservation gains could be made for species through threat-abatement and restoration activities. Quantifiably linking local taxonomic coverage and data collection to global processes with STAR would allow national target setting to align with global targets and enable state and nonstate actors to measure and report on their potential contributions to species conservation.     

Local mate competition and precise sex ratios in Telenomus fariai (Hymenoptera: Scelionidae), a parasitoid of triatomine eggs

Telenomus fariai is a gregarious endoparasitoid of the eggs of several species of Triatominae (Hemiptera) with a high degree of sibmating: males fertilize their sisters inside the host egg before emergence or emerge first and copulate with their sisters as these emerge. Our results show that, when laying alone, T. fariai behaves adaptively, minimizing offspring mortality and conforming to the prediction of local mate competition (LMC) theory by laying a single male, which is sufficient to fertilize all the sisters. When more than one wasp was placed with one host, sex ratios still conformed to LMC predictions but, despite the decreasing number of eggs laid per wasp, clutch size could not be completely adjusted to avoid mortality. This is not surprising, as superparasitism is rare in the field. Offspring production was independent of the contacts between conspecifics but was affected by the number of mothers laying on a single host egg. The sex of the progeny was precisely determined: a female produced one male per clutch when laying on both unparasitized or previously parasitized hosts. On the other hand, a mother produced less daughters when superparasitizing. Under crowded conditions, the number of eggs laid per female wasp and per host decreased as the number of mothers increased. Developmental mortality also increased with the number of T. fariai eggs per host, determining a maximum of approximately 14 emerged adults. Host resources per individual affected male and female adult size with similar intensity, and male adult mortality was slightly higher than that for females. These results, and previous findings, suggest that T. fariai attains Hamiltonian sex ratios by laying one male and a variable number of females, and that the detection of chemical marks left by conspecifics provides information on the number of foundresses sharing a patch. Received: 4 February 2000 / Received in revised form: 19 April 2000 / Accepted: 20 May 2000     

Predictive model for areas with illegal landfills using logistic regression

The existence of illegal landfills is an environmental problem in most countries. However, research on this issue is scarce and limited by the availability and quality of data on the subject. Thus, most illegal landfill studies have only been conducted in a partial manner, focusing on geographical aspects or the causes of these landfills (lack of environmental awareness, inadequate waste management systems, and the role of local government). This research analyses a sample of 120 possible areas with illegal landfills in Andalusia using logistic regression in order to obtain a predictive model for the occurrence of these landfills, including both types of variables (geographical and behavioural) jointly. The results confirm that the variables that most influence the occurrence of illegal landfills are spatial (“Industrial Land”, “Plains” and “Rural Land”); whilst the variables that most reduce the likelihood of illegal landfills are those related to certain characteristics of the municipal waste management system and environmental awareness, such as “Availability of Recycling Facilities”, “Punitive Policies”, “Supervision” and “Awareness-raising Campaigns”. The model obtained shows that variables of very different nature and magnitude interact in the occurrence of illegal landfills, each of which contributes a series of features characteristic of its scale. It is advisable, therefore, to perform an analysis using a multi-scale approach in order to gain an overall understanding of the phenomenon.     

Host range and resistance to aspergillosis in three sea fan species from the Yucatan

Knowledge of host range and mechanisms of disease resistance is fundamental to predicting impacts and spread of marine diseases. Prevalence of signs of aspergillosis, caused by the terrestrial fungus Aspergillus sydowii, was assessed in the Yucatan among three species of sea fan: Gorgonia ventalina, G. cf. mariae, and G. flabellum. The Yucatan is unusual in that ranges of all three sea fan species overlap at many sites along a cline of increasing depth, allowing us to evaluate potential causes of differing prevalence among species. Signs of aspergillosis were observed in all the three species. However, the prevalence of infection in G. cf. mariae, a deep-water species, was consistently low even at sites where G. ventalina was common and had moderate levels of infection. Because G. cf. mariae is a relatively small-stature sea fan, we compared the prevalence of signs in G. cf. mariae to a subset of comparatively sized G. ventalina. G. ventalina had a significantly higher prevalence of aspergillosis, indicating that size does not explain the lower prevalence in G. cf. mariae. Prevalence of disease signs on the shallow-water G. flabellum was also significantly higher than G. cf. mariae, but did not differ from G. ventalina. To test the hypothesis that higher chemical resistance accounts for the low prevalence of disease in G. cf. mariae, we measured the response of A. sydowii in culture to antifungal extracts from each sea fan species. Significantly lower fungal growth rates on extracts of G. cf. mariae than G. ventalina support the hypothesis that G. cf. mariae is more chemically resistant to aspergillosis. When comparing sea fan disease across different regions of the Yucatan, we detected significantly higher prevalence in G. ventalina near Akumal than further north near Cozumel and Puerto Morelos. In Akumal, there was a strong positive correlation between sea fan size and disease, with the largest fans showing the highest prevalence and severity in all three species. In addition, prevalence of aspergillosis in G. ventalina was density-dependent in Ak.     

ARTIFICIAL GROUND WATER RECHARGE EXPERIMENTS IN CARBONATE AND CLASTIC AQUIFERS OF KUWAIT1

ABSTRACT: Injection of water and subsequent withdrawal were carried out in three existing water wells (SU-10, C-105, and SU-135A) in Kuwait. The objective of the study was to assess the technical feasibility of artificial recharge in the carbonate Dammam Formation and the clastic Kuwait Group aquifers. In the absence of any pretreatment of injection water and measures for maintenance of line pressure, clogging from suspended solids and air entrapment occurred in all three experiments. It was, however, possible to inject for one month in Wells SU-10 and C-105 where injection took place in the Dammam aquifer. In Well SU-135A, where the Kuwait Group aquifer was the target for injection, clogging became so severe that the injection experiment had to be abandoned. The injection/withdrawal data were analyzed with the help of a multi-aquifer flow model and a transport model. The models took into account the effects of crossflow within the boreholes on the distribution of intake and discharge rates for different aquifers, and hence, on the recovery efficiency. The experiments suggested that the artificial recharge of the Dammam and the Kuwait Group aquifers was technically feasible. The problem of clogging was, however, more severe for the Kuwait Group.     

Integrated environmental assessment methods: Evolution and applications

The central objectives of the European Forum on Integrated Environmental Assessment (EFIEA) include improving the scientific quality of Integrated Environmental Assessments (IEA) as well as strengthening the interactions between science and policy making in environmental matters. This paper is intended to provide a concise assessment of the evolution of IEA methods and present it as a background to current thinking on and practice in IEA. Historical roots of IEA concepts and applications are explored. Common elements and distinctive features in recent proposals to define IEA are sorted and a liberal definition is proposed for the purposes of the present methodological study. This definition emphasizes the interdisciplinary character and environmental policy orientation of IEAs. Changes in the nature, social perception, and management of environmental problems are identified as the major factors driving methodological development in IEAs. A simple scheme is proposed to arrange the main elements of IEA: disciplinary tools, integration tools, and assessment frameworks. The role of IEAs in environmental management is examined by adopting the concept of risk management functions. Due to the varying needs for interdisciplinary research and diverging degrees of policy involvement across those functions, the potential contribution of IEAs to activities belonging to different functions also varies. The flexibility and diversity of IEAs are demonstrated by a sampler of frameworks that have been developed to address profoundly different problems and audiences. This revised version was published online in July 2006 with corrections to the Cover Date. This revised version was published online in July 2006 with corrections to the Cover Date.