The Continuum Project

This paper examines linkages between the demographic changes taking place in Zaire, particularly overall population growth and rapid urbanization, changes in agricultural practices, and related environmental degradation. Pressures to feed Zaire's rapidly increasing urban population, which fall on a rural population that has been growing relatively slowly in recent years, as well as population growth and increased population density in certain areas of the country, have resulted in changes in agricultural practices that are described in the paper. These changes in turn are leading to declining soil fertility, deforestation, and degradation of the natural resource base. Given present technology and the state of Zaire's economy, the changes in agricultural practices that have emerged in response to population growth, increased population density, and growth in demand for food production do not appear to be sustainable in the long run.

The Bribri have a multifaceted agricultural system relatively high in agrobiodiversity in one of the most biodiverse regions on earth, the forests of Southern Costa Rica. Their agriculture and resource use patterns appear to have evolved over many centuries, informed by traditional ecological knowledge and cultural beliefs about the natural world. Tracing the history of Bribri agriculture from the oldest available documents from the first European contact offers evidence of centuries of crop cultivation, while review of the past century’s records shows socio-economic and natural shocks as key drivers of agricultural change rather than population growth or market pressures. Bribri agricultural systems and practices today have changed in order to adapt yet still rely on traditional ecological knowledge and reflect various cultural beliefs relating to environmental stewardship, resource use, and appreciation of species diversity.

In West Africa, farmers face challenges to innovate and change their practices toward more sustainable cropping systems. Farmer Field Schools (FFS), an advisory service based on participatory principles, aim to support farmers’ innovation. This study investigates farmers’ innovation by characterizing their trajectories of change in agricultural practices after they participated in FFS. Two contrasting types of FFS for family farmers in the cotton-growing area of West Africa were selected. The FFS differed in how they were implemented; farmer participation was either consultative (farmers participated little in developing the FFS curricula and structure) or collaborative (farmers participated actively in developing the FFS curricula and structure). Former FFS participants were interviewed on their successive changes in cropping practices over a 4 to 8-year time span. The sample included seven FFS on rainy season cropping (17 interviews in Burkina Faso, 22 in Togo), and four vegetable gardening FFS (21 interviews in Togo). The Efficiency-Substitution-Redesign framework was applied to pest management, organic and mineral fertilization and legume cropping practices. Our results show that the way FFS were implemented influenced farmers’ trajectories of change in practices. After consultative FFS, changes in practices were limited. After collaborative FFS, we found a variety of changes in the production and use of compost, biopesticides, and inclusion of legumes in the cropping system through intercropping or pure cropping. Redesign of cropping systems included increasing on-farm compost production, collective pest management, and crop rotations. Collaborative FFS can be seen as step-by-step design processes for locally adapted cropping systems. This is the first time that farmers’ trajectories of change in practices are used to assess the effects of FFS. This approach is valuable for understanding farmers’ decision making and the role of participatory innovation support initiatives such as FFS.

Understanding changes in reducing pesticide use by farmers: Contribution of the behavioural sciences

Stream water quality can be greatly influenced by changes in agricultural practices, but studies of long-term dynamics are scarce. Here we describe trends over 21 yr (1994-2014) in nutrients and suspended sediments in three streams in a Midwestern US agricultural watershed. During this time, the watershed experienced substantial changes in agricultural practices, most importantly a pronounced shift from conventional to conservation tillage. In the 1990s and early 2000s, NH, soluble reactive P, and suspended sediment concentrations (standardized for discharge and season) each declined significantly (>4-12% per year) in at least two of the three streams ( < 0.01), whereas NO changed relatively little. However, since the early 2000s, declines in NH and sediment concentrations have slowed, soluble reactive P concentrations have not declined and may actually have increased, and NO concentrations have declined sharply. The more recent lack of decline in soluble reactive P coincides with a plateau in the prevalence of conservation tillage and may be because of increased soil P stratification due to long-term reduced tillage. The more recent decline in NO may be due to improved efficiency of N fertilizer use, increased soil denitrification, and/or declines in atmospheric N deposition. Our study shows that stream concentrations of N, P, and sediment can respond in contrasting ways to changes in agriculture, and that temporal trends can moderate, accelerate, or reverse over decadal timescales. Management strategies must consider contrasting temporal responses of water quality indicators and may need to be adaptively adjusted at scales of years to decades.

ContextEcological networks (i.e. sets of connected natural habitats) emerged in the 1980s and have been implemented worldwide. They have been developed as a land-use planning tool that enables to ensure both habitat amount and landscape connectivity in response to ground based physical anthropogenic drivers (e.g. forest cuttings, roads, dams).Objective We wanted to highlight some gaps in this conception of habitat loss and fragmentation that led to potential lacks in the current methods and approaches to design and manage ecological networks, with a view to suggest a way of improving the situation for a more comprehensive consideration of biodiversity.MethodsWe compared new scientific knowledge about habitat loss and fragmentation with a critical assessment of feedback from ecological networks, in order to highlight bottlenecks. On this basis we formulated proposals for a new framework and discussed the operational implications for designing and managing broader ecological networks.ResultsAirscape or soils—key compartments for activities and movements of species—appear to be rarely considered in ecological networks, as well as sensory pollutants—i.e. artificial light at night, man-induced sounds and odors—while they have been demonstrated to disturb nightscapes, soundscapes and odorscapes.ConclusionWe invite landscape designers and decision-makers to transition to multidimensional ecological networks, developing specific infrastructure against habitat loss and fragmentation, in particular an aerial infrastructure for flying species, a brown infrastructure for soil wildlife, a dark infrastructure for darkness at night, a noise-free infrastructure and an olfactory infrastructure to deal with anthropogenic odors.

Habitat loss and fragmentation are recognized as affecting the nature of biotic interactions, although we still know little about such changes for reptilian herbivores and their hindgut nematodes, in which endosymbiont interactions could range from mutualistic to commensal and parasitic. We investigated the potential cost and benefit of endosymbiont interactions between the spur-thighed tortoise (Testudo graeca L.) and adult oxyurid nematodes (Pharyngodonidae order Oxyurida) in scrublands of southern Spain. For this, we assessed the association between richness and abundance of oxyurid species with tortoises’ growth rates and body traits (weight and carapace length) across levels of habitat loss (low, intermediate and high). Furthermore, by using an intrapopulation ecological network approach, we evaluated the structure and diversity of tortoise–oxyurid interactions by focusing on oxyurid species infesting individual tortoises with different body traits and growth rates across habitats. Overall, tortoise body traits were not related to oxyurid infestation across habitats. Oxyurid richness and abundance however, showed contrasting relationships with growth rates across levels of habitat loss. At low habitat loss, oxyurid infestation was positively associated with growth rates (suggesting a mutualistic oxyurid–tortoise relationship), but the association became negative at high habitat loss (suggesting a parasitic relationship). Furthermore, no relationship was observed when habitat loss was intermediate (suggesting a commensal relationship). The network analysis showed that the oxyurid community was not randomly assembled but significantly nested, revealing a structured pattern for all levels of habitat loss. The diversity of interactions was lowest at low habitat loss. The intermediate level, however, showed the greatest specialization, which indicates that individuals were infested by fewer oxyurids in this landscape, whereas at high habitat loss individuals were the most generalized hosts. Related to the latter, connectance was greatest at high habitat loss, reflecting a more uniform spread of interactions among oxyurid species. At an individual level, heavier and larger tortoises tended to show a greater number of oxyurid species interactions. We conclude that there is an association between habitat loss and the tortoise–oxyurid interaction. Although we cannot infer causality in their association, we hypothesize that such oxyurids could have negative, neutral and positive consequences for tortoise growth rates. Ecological network analysis can help in the understanding of the nature of such changes in tortoise–oxyurid interactions by showing how generalized or specialized such interactions are under different environmental conditions and how vulnerable endosymbiont interactions might be to further habitat loss.

Despite the fact that Japan generally receives a considerable amount of rainfall annually, the steep terrain and limited size of rivers results in rapid outflow to the sea. Consequently, in numerous regions of Japan, small-scale agricultural reservoirs have emerged as the predominant water storage infrastructure and the primary source of water for irrigating rice paddies. It is estimated that there are approximately 150,000 such reservoirs in Japan, with the majority having been constructed over a century ago. This study investigates how changes in rainfall patterns due to climate change and the aging of the population, as well as the accompanying changes in agricultural practices, particularly in rural areas, are affecting the fate of Japan's agricultural reservoirs.In the present study, the primary objective was to establish a comprehensive database of reservoirs. Despite the availability of official data on reservoirs, it has been observed that this data does not accurately reflect the current situation, particularly in the case of small reservoirs. This is primarily due to the large number of reservoirs and the limited capacity of the government to effectively monitor these bodies of water. Additionally, the database has not been updated to reflect the changes in the reservoir environment that have occurred in tandem with the rapid advancements in agricultural practices and the shifting social landscape, characterized by declining birth rates and an aging population. To address these challenges, we have developed a technology capable of detecting these reservoirs through the analysis of aerial images and satellite observations.The results of case studies of several regions based on the database suggest that the background to the abandonment and abandonment of small reservoirs is the decline in demand and the existence of modern irrigation facilities that make it possible to use the water of large-scale, highly efficient reservoirs rather than small reservoirs nearby. A significant proportion of these reservoirs, constituting the bulk of the total number of reservoirs, have been either abandoned or are on the verge of being abandoned, particularly those with a capacity of less than 10,000 m3. This is primarily attributable to their suboptimal utilization and management efficiency. Moreover, it has been observed that the recent increase in precipitation in the form of heavy rainfall has accentuated the risks associated with reservoirs. Consequently, stakeholders are being prompted to make decisions that lead to the abandonment or closure of these reservoirs. This presentation will draw from the trends in the fate of reservoirs for agricultural use in Japan, with a focus on abandonment and closure, to discuss sustainable and effective water management and the various environmental and socio-economic factors that affect reservoirs.

Long and short-term trends of stream hydrochemistry and high frequency surveys as indicators of the influence of climate change, agricultural practices and internal processes (Aurade agricultural catchment, SW France)

Mitigation of emerging implications of climate change on food production systems

Changes in microbial community structure and physiological profile in a kaolinitic tropical soil under different conservation agricultural practices

Global warming and climate change, deriving from human activity, have become recognized as a major contributor to the increase occurrence of natural disaster events worldwide. In Malaysia excessive rainfall in conjunction with deforestation and changes in agricultural practices has led to excessive flooding in many parts of the country. Zulisman Maksom studied how community based flood warning would benefit the current systems. His research use Activity Theory in order to establish the most effective and appropriate tolls to use in designing communication systems for risk reduction in relation to floods in the Malaysian context. This has given researchers a better understanding of an important communication design to the future flood warning systems development.

Seasonal variability of turbidity, salinity, temperature and suspended chlorophyll in a strongly tidal sub-estuary: The Lynher Marine Conservation Zone

Emergence and re-emergence of foodborne pathogens is a continuing concern for public health agencies and organizations, the food industry, and consumers. Several factors that contribute to the emergence include changes in the behavior of microorganisms and consumers, changes in agricultural practices and animal husbandry, increase in foreign travel, food distribution through a global marketplace, and climate changes. Furthermore, advances in molecular technologies and pathogen detection methods are allowing increased recognition of the presence of new pathogens. Emerging foodborne pathogens are often zoonotic in origin and may include Gram-negative and Gram-positive bacteria, parasites, and viruses. Previously established foodborne pathogens may re-emerge as more virulent pathogens after the acquisition of new virulence factors, including antibiotic resistance determinants. In this review, various important emerging foodborne pathogens, including non-O157 Shiga toxin–producing Escherichia coli serogroups, pathogenic hybrid E. coli , extraintestinal pathogenic E. coli, drug-resistant foodborne bacteria, Clostridium difficile , hepatitis E virus, and others, are discussed, as well as factors that may be involved in their emergence. Reducing the number of foodborne illnesses and the emergence/re-emergence of pathogens require global partnerships among government agencies, the food industry, and other groups involved in food safety.

Increasing levels of dissolved organic matter (DOM) in watercourses in the northern hemisphere are mainly due to reduced acid rain, climate change, and changes in agricultural practices. However, their impacts vary in time and space. To predict how DOM responds to changes in environmental pressures, we need to differentiate between allochthonous and autochthonous sources as well as identify anthropogenic DOM. In this study we distinguish between allochthonous, autochthonous, and anthropogenic sources of DOM in a diverse watercourse network by assessing effects of land cover on water quality and using DOM characterization tools. The main sources of DOM at the studied site are forests discharging allochthonous humic DOM, autochthonous fulvic DOM, and runoff from urban sites and fish farms with high levels of anthropogenic DOM rich in protein-like material. Specific UV absorbency (sUVa) distinguishes allochthonous DOM from autochthonous and anthropogenic DOM. Anthropogenic DOM differs from autochthonous fulvic DOM by containing elevated levels of protein-like material. DOM from fishponds is distinguished from autochthonous and sewage DOM by having high sUVa. DOM characteristics are thus valuable tools for deconvoluting the various sources of DOM, enabling water resource managers to identify anthropogenic sources of DOM and predict future trends in DOM.