Weed management is a major challenge in organic crop production, and organic farms generally harbor larger weed populations and more diverse communities compared with conventional farms. However, little research has been conducted on the effects of different organic management practices on weed communities and crop yields. In 2014 and 2015, we measured weed community structure and soybean [Glycine max (L.) Merr.] yield in a long-term experiment that compared four organic cropping systems that differed in nutrient inputs, tillage, and weed management intensity: (1) high fertility (HF), (2) low fertility (LF), (3) enhanced weed management (EWM), and (4) reduced tillage (RT). In addition, we created weed-free subplots within each system to assess the impact of weeds on soybean yield. Weed density was greater in the LF and RT systems compared with the EWM system, but weed biomass did not differ among systems. Weed species richness was greater in the RT system compared with the EWM system, and weed community composition differed between RT and other systems. Our results show that differences in weed community structure were primarily related to differences in tillage intensity, rather than nutrient inputs. Soybean yield was lower in the EWM system compared with the HF and RT systems. When averaged across all four cropping systems and both years, soybean yield in weed-free subplots was 10% greater than soybean yield in the ambient weed subplots that received standard management practices for the systems in which they were located. Although weed competition limited soybean yield across all systems, the EWM system, which had the lowest weed density, also had the lowest soybean yield. Future research should aim to overcome such trade-offs between weed control and yield potential, while conserving weed species richness and the ecosystem services associated with increased weed diversity.

The literature on age-friendly communities is predominantly focused on a model of urban aging, thereby failing to reflect the diversity of rural communities. In this article, we address that gap by focusing on the concept of community in a rural context and asking what makes a good fit between older people and their environment. We do this through (a) autobiographical and biographical accounts of two very different geographical living environments: bucolic and bypassed communities; and through (b) analysis of the different needs and resources of two groups of people: marginalized and community-active older adults, who live in those two different rural communities. We argue that the original 2007 World Health Organization definition of age friendly should be reconceptualized to explicitly accommodate different community needs and resources, to be more inclusive as well as more interactive and dynamic, incorporating changes that have occurred over time in people and place.

The prediction that richness and diversity of helminth communities would be greater in tropical fish was tested by analysing total and intestinal helminth communities in samples of Anguilla reinhardtii taken from 10 localities in tropical and semi-tropical freshwaters in Queensland, Australia. Comparison of findings with those from A. anguilla in the UK revealed that regional species richness was higher in Queensland and that helminth communities harboured a suite of common species, virtually all eel specialists, that were responsible for the observed higher levels of similarity between component communities. All measures of community richness and diversity adopted indicated that the poorest helminth communities in A. reinhardtii were comparable with the richest ones reported from the northern temperate A. anguilla. The richest communities in A. reinhardtii were more diverse than those reported from any other species of fish, whether marine or freshwater, to date, and were comparable with the communities found in some species of aquatic birds. Both tropical conditions and age and endemism of the host, i.e. the time hypothesis, were considered as explanations for this richness but neither could be favoured. A cautious approach to generalizations based on data from temperate regions only is advocated, and the need for more studies on tropical parasite communities is strongly emphasized.

We studied patterns of variation in parasite communities of 2 closely related species of Mastomys rodents. These 2 species live in sympatry in South-eastern Senegal, but differ drastically in their habitat choice. We asked (a) whether the host species have the same parasites; (b) whether there is any observable pattern relative to the host species/habitat type in the structure of parasite communities; (c) whether the variability in parasite community for each host species is related to habitat characteristics. We analysed 220 and 264 individuals of each host species, sampled respectively in 10 and 11 trap sites. Twenty parasite taxa were recorded, and the majority were nematodes. Between-host species comparisons showed that helminth communities were slightly more diversified in M. natalensis. Many parasite species were found in both Mastomys. However, various helminth taxa varied in frequency and abundance between host species. Within each host species, helminth diversity, prevalence and/or abundance of some parasites were correlated with habitat or host population factors that may influence parasite life-cycles, such as village structure, or the presence/absence of a pool. Our results suggest that habitat characteristics have a strong impact on helminth community structure.

We studied oribatid (Acari: Oribatida) communities in two distinct microhabitats (litter and root) of the bird's nest fern (Asplenium nidus) in an approximately 4-ha area in a subtropical forest, Okinawa, Japan. We collected a total of 15 729 oribatid mites from 37 ferns and examined whether the size and height of the ferns and the distance between ferns affected the structure of the oribatid communities in terms of the species composition, number of individuals, density (individuals per 100 g dry wt of substrate), number of species and species diversity (Simpson's index). Oribatid communities differed significantly in species composition and density between litter and root components and were evenly distributed horizontally throughout the plot. The density of oribatid mites in the litter decreased significantly with increasing height of the ferns, and the species composition and the numbers of individuals and species in the litter were affected by fern size. Our results suggest that the litter and root of bird's nest ferns allowed diverse oribatid communities to become established, and variations in size and height of the ferns may help to maintain or enhance the diversity of oribatid communities in bird's nest ferns in subtropical forests.

The composition, richness and similarity of helminth communities in a tropical freshwater fish were determined in samples of Cichlasoma urophthalmus collected from 7 localities of broadly similar age and character situated along the northern coast of the Yucatan peninsula, Mexico. The component communities exhibited a unique combination of characteristics for a freshwater fish. They were dominated by digeneans, with all other helminth groups being numerically inferior. A common suite of species could be recognized, but many of its members were generalists and not cichlid specialists. Species richness and number of individuals per host were high, but diversity was low, reflecting high dominance by one species. Intra- and inter-locality similarity levels were low, and local variation high. In respect of species richness and digenean dominance, the communities resembled those in Australian tropical anguillids, but in respect of low diversity, similarity and high dominance they are more similar to helminth communities of northern temperate fish.