Mesure de la vulnérabilité des milieux urbains au Cameroun face au changement climatique

Les différentes catastrophes survenues en milieu urbain au Cameroun récemment, mettent en exergue les désormais dangers permanents qui pèsent sur les habitants. On note une augmentation des extrêmes : de hautes températures, des perturbations des régimes pluvieux et la récurrence des vents violents. Certains de ces effets sont amplifiés par la géographie contraignante de plusieurs villes et par l’influence anthropique sur l’environnement. En effet, d’une part les sites de plusieurs villes camerounaises ont soit des reliefs accidentés qui favorisent l’érosion des terrains, soit des configurations planes qui limitent l’évacuation gravitaire de l’eau de ruissellement. D’autre part, la croissance urbaine rapide et la prolifération des bidonvilles qui couvrent près de 65 à 70% de la superficie urbaine, usent plus rapidement les ouvrages et infrastructures d’assainissement urbaines lorsqu’ils existent dus à l’imperméabilisation accélérée et continue du sol urbain ainsi qu’à la mauvaise gestion des déchets. L’urgence de trouver des solutions durables à ce phénomène est désormais sans équivoque. Elle nécessite un encadrement normatif inclusif plus performant que celui actuellement en vigueur, qui amène le pays vers la résilience. The disasters that’ve occurred recently in urban areas in Cameroon, highlight the permanent dangers weighing on the inhabitants. There is an increase in extremes climate parameters: high temperatures, rainfall disturbances and the recurrence of gales. Some of these effects are amplified by both the constraining relief of several cities and human influence on the environment. In fact, on the one hand, the sites of several Cameroonian cities either have rugged reliefs that promote land erosion, or flat configurations that limit the gravity discharge of runoff water. On the other hand, the rapid urban growth and the proliferation of slums which cover nearly 65 to 70% of the urban area, wear out more quickly the works and urban sanitation infrastructures when they exist due to the accelerated and continuous waterproofing soil in addition to the poor waste management. The urgency to find lasting solutions to this phenomenon is now unequivocal. It requires an inclusive normative framework that is more effective than that currently in force, which brings the country towards resilience.

Characteristics of and Influencing Factors of Hydrochemistry and Carbon/Nitrogen Variation in the Huangzhouhe River Basin, a World Natural Heritage Site

In karst areas, the characteristics of water chemistry and carbon and nitrogen are of great significance to basic research. The contents of Ca2+, Mg2+, K+, Na+, HCO3−, SO42−, NO3−, Cl−, dissolved organic carbon (DOC), and total nitrogen (TN) in water samples from 18 rivers and 14 springs in the Huangzhouhe River Basin were determined. The results showed that the water chemistry type in the Huangzhouhe River Basin is HCO3-Ca-Mg. The chemical composition is mainly affected by dolomite weathering and also by ion exchange and other human activities. The river and spring DIC remain at the same level in the upper and middle reaches and decrease in the lower reaches. The NO3-N and TN of river water and TN of spring water increase in the middle reaches, while NO3-N of spring water decreases in the lower reaches. The DOC in the basin increases with the increase of SO42− and Cl−, mainly due to the human influence of agricultural and domestic sewage. In the basin, the NO3-N and TN in spring water are larger, and the DOC in river water is larger, mainly because there are more phytoplankton and human activities in the river water. The carbon and nitrogen in the Huangzhouhe River Basin are mainly HCO3− and NO3− ions. The evaluation of pH, Cl−, NO3-N, SO42−, and TDS shows that the water quality is good and the ecological environment is good.

Conservation and Management of the Culture of Bears

ABSTRACT: Culture is widely accepted as an important social factor present across a wide range of species. Bears have a culture as defined as behavioral traditions inherited though social learning usually from mothers to offspring. Successful bear cultures can enhance fitness and resource exploitation benefits. In contrast, some bear cultures related to response to humans and human-related foods can be maladaptive and result in reduced fitness and direct mortality. In environments with minimal human influence most bear culture has evolved over generations to be beneficial and well adapted to enhance fitness. However, most bears across the world do not live in areas with minimal human influence and in these areas, bear culture is often changed by bear interactions with humans, usually to the detriment of bear survival. We highlight the importance of identifying unique bear cultural traits that allow efficient use of local resources and the value of careful management to preserve these adaptive cultural behaviors. It is also important to select against maladaptive cultural behaviors that are usually related to humans inorder to reduce human-bear conflicts and high bear mortality. We use examples from Yellowstone National Park to demonstrate how long-term management to reduce maladaptive bear cultures related to humans has resulted in healthy bear populations and a low level of human-bear conflict in spite of a high number of Park visitors in close association with bears.

Editorial for the Special Issue on Modelling and Simulation of Human-Environment Interactions

At the core of the Anthropocene lies human influence on the environment [...]

Defining dual-axis landscape gradients of human influence for studying ecological processes

Ecological processes are strongly shaped by human landscape modification, and understanding the reciprocal relationship between ecosystems and modified landscapes is critical for informed conservation. Single axis measures of spatial heterogeneity proliferate in the contemporary gradient ecology literature, though they are unlikely to capture the complexity of ecological responses. Here, we develop a standardized approach for defining multi-dimensional gradients of human influence in heterogeneous landscapes and demonstrate this approach to analyze landscape characteristics of ten ecologically distinct US cities. Using occupancy data of a common human-adaptive songbird collected in each of the cities, we then use our dual-axis gradients to evaluate the utility of our approach. Spatial analysis of landscapes surrounding ten US cities revealed two important axes of variation that are intuitively consistent with the characteristics of multi-use landscapes, but are often confounded in single axis gradients. These were, a hard-to-soft gradient, representing transition from developed areas to non-structural soft areas; and brown-to-green, differentiating between two dominant types of soft landscapes: agriculture (brown) and natural areas (green). Analysis of American robin occurrence data demonstrated that occupancy responds to both hard-to-soft (decreasing with development intensity) and brown-to-green gradient (increasing with more natural area). Overall, our results reveal striking consistency in the dominant sources of variation across ten geographically distinct cities and suggests that our approach advances how we relate variation in ecological responses to human influence. Our case study demonstrates this: robins show a remarkably consistent response to a gradient differentiating agricultural and natural areas, but city-specific responses to the more traditional gradient of development intensity, which would be overlooked with a single gradient approach. Managing ecological communities in human dominated landscapes is extremely challenging due to a lack of standardized approaches and a general understanding of how socio-ecological systems function, and our approach offers promising solutions.

Determinants of species assemblages of insect pests in alpine forest ecosystems of western China

Background Insect pests are a significant threat to natural resources and social development. Modeling species assemblages of insect pests can predict spatiotemporal pest dynamics. However, research gaps remain regarding the mechanism for determining species assemblages of insect pests in alpine forest ecosystems. Here, we explored these determinants using a field investigation conducted for insect pests in a region of the Qinghai-Tibet Plateau. We assessed the species assemblages of insect pests in alpine forest ecosystems based on species co-occurrence patterns and species diversity (i.e., observed diversity, dark diversity, community completeness, and species pool). A probabilistic model was used to test for statistically significant pairwise patterns of species co-occurrence using the presence-absence matrix of pest species based on species interactions. We used ordinary least squares regression modeling to explore relationships between abiotic factors (i.e., climate factors and human influence) and species diversity. Results Positive pest species interactions and many association links can occur widely across different investigation sites and parts of plant hosts in alpine forest ecosystems. We detected high dark diversity and low community completeness of insect pests in alpine forest ecosystems. High temperature and precipitation could promote pest species diversity, particularly dark diversity and species pools. Human influence could drive high levels of pest species diversity and lead to dark diversity and species pools. Community completeness could be an effective indicator for insect pest risk assessment. Conclusions Our study provides new evidence for the determinants of insect pest species assemblages in alpine forest ecosystems from the perspectives of pest species interactions and abiotic factors. The findings of our study could reveal the mechanism for shaping species assemblages and support the prevention and control of insect pests in alpine forest ecosystems.

Human Impact on Antler Conformation in Western Red Deer (Cervus elaphus elaphus Linnaeus, 1758)

A stray find of red deer antler from Sweden with the braincase was collected due to an apparently pathological deformation, the strongly retarded right antler. Measurements of the complete left antler inspired the analysis of general antler conformation in order to place this archaeological specimen in a zoological context. This stray find and another prehistoric antler from Sweden as well as three complete prehistoric antlers from Hungary were metrically compared using measurements of over 17,000 trophies of extant red deer from Hungary. The results confirmed that the stray specimen from Sweden and prehistoric antlers from Hungary were similar in that they were stouter (smaller length measurements but greater circumferences) than their 20th century counterparts. Most of their measurements fell within the ±1 standard deviation interval of the means of extant trophies. The pathological lesion on the studied stray specimen directed attention to the role of human selection. Twentieth century record trophies show a significant increase in antler weight and “quality” as defined in the international trophy grading system. While these morphometric observations cannot be taken as a proxy for absolute dating or precise contextual identification for the stray find central to this study, its size and apparent lack of consistent human selection (pathological deformation, “archaic” antler proportions) point to possibly early origins, prior to major human influence.