Use patterns of natural resources supporting livelihoods of smallholder communities and implications for climate change adaptation in Zimbabwe

Declining crop and livestock production due to a degrading land resource base and changing climate among other biophysical and socio-economic constraints, is increasingly forcing rural households in Zimbabwe and other parts of Southern Africa to rely on common natural resource pools (CNRPs) to supplement their household food and income. Between 2011 and 2013, we combined farmer participatory research approaches, remote sensing and geographic information systems (GIS) to (1) understand the contribution of CNRPs to household food and income in Dendenyore and Ushe smallholder communities in Hwedza District, eastern Zimbabwe and (2) assess changes of the CNRPs in both space and time, and their implications on climate change adaptation. Across study sites, wetlands and woodlands were ranked as the most important CNRPs. Extraction and use patterns of products from the different pools differed among households of different resource endowment. Resource-constrained households (RG3) sold an average of 183 kg household^?1 year^?1 of wild loquats fruits (Uapaca kirkiana), realising about US$48, while resource-endowed farmers (RG1) had no need to sale any. The RG3 households also realised approximately US$70 household^?1 year^?1 from sale of crafts made from water reeds (Phragmites mauritianus). Empirical data closely supported communities’ perceptions that CNRPs had declined significantly in recent years compared with two to three decades ago. More than 60 % of the respondents perceived that the availability of natural resources drawn from wetlands and woodlands, often used for food, energy and crafts, has decreased markedly since the 1980s. Classification of land cover in a GIS environment indicated that CNRPs declined between 1972 and 2011, supporting farmers’ perceptions. Overall, woodlands declined by 37 % in both communities, while the total area under wetlands decreased by 29 % in Ushe, a drier area and 49 % in Dendenyore, a relatively humid area. The over-reliance in CNRPs by rural communities could be attributed to continued decline in crop yields linked to increased within-season rainfall variability, and the absence of alternative food and income sources. This suggests limited options for rural communities to adapt to the changing food production systems in the wake of climate change and variability and other challenges such as declining soil fertility. There is therefore a need to design adaptive farm management options that enhance both crop and livestock production in a changing climate as well as identifying other livelihood alternatives outside agriculture to reduce pressure on CNRPs. In addition, promotion of alternative sources of energy such as solar power and biogas among rural communities could reduce the cutting of trees for firewood from woodlands.     

Different Pla Grafting Techniques on Chitosan

PLA grafting on chitosan has been successfully prepared with two different methods: a direct grafting method and the ROP method. The thermal properties showed that the copolymerization of PLA on the chitosan’s chain by direct grafting is more thermostable than the one obtained by the ROP method.     

Framework and Tools for Agricultural Landscape Assessment Relating to Water Quality Protection

While many scientific studies show the influence of agricultural landscape patterns on water cycle and water quality, only a few of these have proposed scientifically based and operational methods to improve water management. Territ’eau is a framework developed to adapt agricultural landscapes to water quality protection, using components such as farmers’ fields, seminatural areas, and human infrastructures, which can act as sources, sinks, or buffers on water quality. This framework allows us to delimit active areas contributing to water quality, defined by the following three characteristics: (i) the dominant hydrological processes and their flow pathways, (ii) the characteristics of each considered pollutant, and (iii) the main landscape features. These areas are delineated by analyzing the flow connectivity from the stream to the croplands, by assessing the buffer functions of seminatural areas according to their flow pathways. Hence, this framework allows us to identify functional seminatural areas in terms of water quality and assess their limits and functions; it helps in proposing different approaches for changing agricultural landscape, acting on agricultural practices or systems, and/or conserving or rebuilding seminatural areas in controversial landscapes. Finally, it allows us to objectivize the functions of the landscape components, for adapting these components to new environmental constraints.     

Temporal trend of mercury in polar bears (Ursus maritimus) from Svalbard using teeth as a biomonitoring tissue

We examined the use of mercury (Hg) and nitrogen and carbon stable isotopes in teeth of polar bear (Ursus maritimus) from Svalbard as biotracers of temporal changes in Hg pollution exposure between 1964 and 2003. Teeth were regarded as a good matrix of the Hg exposure, and in total 87 teeth of polar bears were analysed. Dental Hg levels ranged from 0.6 to 72.3 ng g(-1) dry weight and increased with age during the first 10 years of life. A decreasing time trend in Hg concentrations was observed over the recent four decades while no temporal changes were found in the stable isotope ratios of nitrogen (δ(15)N) and carbon (δ(13)C). This suggests that the decrease of Hg concentrations over time was more likely due to a lower environmental Hg exposure in this region rather than a shift in the feeding habits of Svalbard polar bears.     

Phylogenetic diversity and functional characterization of the Manila clam microbiota: a culture-based approach

According to the hologenome theory, the microbiota contributes to the fitness of the holobiont having an important role in its adaptation, survival, development, health, and evolution. Environmental stress also affects the microbiota and its capability to assist the holobiont in coping with stress factors. Here, we analyzed the diversity of cultivable bacteria associated with Manila clam tissues (mantle, gills, hemolymph) in two non-contaminated sites (Portugal and France) and one metal-contaminated site (Portugal). A total of 240 isolates were obtained. Representative isolates (n = 198) of the overall diversity were identified by 16S rDNA sequencing and subjected to functional characterization. Isolates affiliated with Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes. Proteobacteria (mostly Pseudoalteromonadaceae and Vibrionaceae) were dominant in non-contaminated sites while Actinobacteria (mostly Microbacteriaceae) dominated in the metal-contaminated site. The main factor affecting the microbiota composition was contamination. No significant differences were observed between clam tissues and geographic regions. Several isolates tested positive for antibacterial activity, biofilm formation, protease, and siderophore production. The results show that the Manila clam harbors a diverse microbiota that may contribute to clam protection and overall fitness, as well as to its adaptation to stressful environments. In addition, the Manila clam microbiota is revealed as a promising source of novel probiotics with potential application in aquaculture.     

CeO2 nanoparticle fate in environmental conditions and toxicity on a freshwater predator species: a microcosm study

Environmental Science and Pollution Research - We studied the fate and toxicity of two types of CeO2 NPs (bare or citrate-coated) in environmentally relevant conditions, using large indoor...     

Invasive Knotweeds are Highly Tolerant to Salt Stress

Japanese knotweed s.l. are some of the most invasive plants in the world. Some genotypes are known to be tolerant to the saline concentrations found in salt marshes. Here we focus on tolerance to higher concentrations in order to assess whether the species are able to colonize and establish in highly stressful environments, or whether salt is an efficient management tool. In a first experiment, adult plants of Fallopia japonica, Fallopia?×?bohemica and Fallopia sachalinensis were grown under salt stress conditions by watering with saline concentrations of 6, 30, 120, or 300?g?L^?1 for three weeks to assess the response of the plants to a spill of salt. At the two highest concentrations, their leaves withered and fell. There were no effects on the aboveground parts at the lowest concentrations. Belowground dry weight and number of buds were reduced from 30 and 120?g?L^?1 of salt, respectively. In a second experiment, a single spraying of 120?g?L^?1 of salt was applied to individuals of F.?×?bohemica and their stems were clipped to assess the response to a potential control method. 60?% of the plants regenerated. Regeneration was delayed by the salt treatment and shoot growth slowed down. This study establishes the tolerance of three Fallopia taxa to strong salt stress, with no obvious differences between taxa. Their salt tolerance could be an advantage in their ability to colonize polluted environments and to survive to spills of salt.     

Atmospheric pollution in an urban environment by tree bark biomonitoring--part I: trace element analysis

Tree bark has been shown to be a useful biomonitor of past air quality because it accumulates atmospheric particulate matter (PM) in its outermost structure. Trace element concentrations of tree bark of more than 73 trees allow to elucidate the impact of past atmospheric pollution on the urban environment of the cities of Strasbourg and Kehl in the Rhine Valley. Compared to the upper continental crust (UCC) tree barks are strongly enriched in Mn, Ni, Cu, Zn, Cd and Pb. To assess the degree of pollution of the different sites in the cities, a geoaccumulation index I_geo was applied. Global pollution by V, Ni, Cr, Sb, Sn and Pb was observed in barks sampled close to traffic axes. Cr, Mo, Cd pollution principally occurred in the industrial area. A total geoaccumulation index I_GEO-tot was defined; it is based on the total of the investigated elements and allows to evaluate the global pollution of the studied environment by assembling the I_geo indices on a pollution map.     

Low impact of phenanthrene dissipation on the bacterial community in grassland soil

The effect of phenanthrene on the bacterial community was studied on permanent grassland soil historically presenting low contamination (i.e. less than 1 mg kg^?1) by polycyclic aromatic hydrocarbons (PAHs). Microcosms of soil were spiked with phenanthrene at 300 mg kg^?1. After 30 days of incubation, the phenanthrene concentration decreased rapidly until its total dissipation within 90 days. During this incubation period, significant changes of the total bacterial community diversity were observed, as assessed by automated-ribosomal intergenic spacer analysis fingerprinting. In order to get a deeper view of the effect of phenanthrene on the bacterial community, the abundances of ten phyla and classes (Actinobacteria, Acidobacteria, Bacteroidetes, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Firmicutes, Verrucomicrobiales, Gemmatimonadetes, and Planctomycetes) were monitored by quantitative polymerase chain reaction performed on soil DNA extracts. Interestingly, abundances of some bacterial taxa significantly changed as compared with controls. Moreover, among these bacterial groups impacted by phenanthrene spiking, some of them presented the potential of phenanthrene degradation, as assessed by PAH-ring hydroxylating dioxygenase (PAH-RHD_α) gene detection. However, neither the abundance nor the diversity of the PAH-RHD_α genes was significantly impacted by phenanthrene spiking, highlighting the low impact of this organic contaminant on the functional bacterial diversities in grassland soil.