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The effect of climate at origin on Douglas-fir growth, leaf traits and embolism resistance along a rainfall gradient in Central Europe
Get PDFIn Central Europe, the economically most important timber species for roundwood production, Norway spruce, has been severely affected by recent global change-type drought events. Due to its large spatial distribution, Douglas-fir (Pseudotsuga menziesii) is considered for conversion to climate-resilient forests. Specifically, provenances from moister coastal and drier and colder interior regions might differ in drought tolerance traits. Here, we characterized aboveground biomass increment as well as leaf morphological and plant hydraulic traits in mature trees of 28 Douglas-fir provenances from three climate-at-origin groups across a climatic gradient in Central Europe, covering a precipitation range of 542 mm yr−1. Irrespective of the gradient, the northern interior provenances had a 5.4 kg yr−1 lower aboveground biomass increment than the two coastal groups, accompanied by a 13% smaller specific leaf area. On the other hand, the Huber value, embolism resistance (P50) and leaf carbon isotope signature (δ13C) as proxy for long-term intrinsic water use efficiency did not differ between climate-origin groups. Across the gradient and within a climate-origin-group, no effect of climatic aridity on any of the traits covered was observed. Especially P50 showed very little intra-specific variability, and our observed mean of −3.5 MPa is in the same range as P50-values for Douglas-fir recently reported from Europe. Our results for Douglas-fir support that xylem safety is a rather conservative and evolutionary canalized trait in conifers, while the Huber value revealed less plasticity as expected. Future studies are needed to test whether slower-growing interior provenances with thicker and smaller needles might be more drought tolerant and thus better suited for cultivation in the future climate of Central Europe although xylem safety does not differ
Intercrop overyielding is maintained under estimated water and nitrogen stress in maize-cowpea on-farm trials in semi-arid Zimbabwe
Get PDFProblem: Semi-arid regions of sub-Saharan Africa are characterized by highly variable rainfall and low inherent soil fertility. Maize-cowpea intercropping may offer the prospect of increasing and stabilizing crop productivity in these regions. However, the performance of such cropping systems often varies considerably in space and time. Objective: The main objective of the study was to understand how farmer context and rainfall variability influence the performance of maize-cowpea intercropping, using on-farm field experiments together with soil-crop model simulations to compute water and nitrogen stress. Methods: The data used in this study was generated from twelve on-farm trials during two cropping seasons (2021/22 and 2022/23) in semi-arid Zimbabwe. Three maize (Zea mays L.) varieties, one cowpea (Vigna unguiculata (L.) Walp.) variety and two cropping systems - either sole or intercropped - were tested. The STICS soil-crop model was parameterized to reproduce crop growth in the on-farm trials and compute water and nitrogen (N) stresses. Linear mixed-effects models were used to assess the impact of experimental treatments and simulated water and N stresses on intercropping performance. Results: The Partial Land Equivalent Ratio (pLER – the ratio of intercropped productivity over sole crop productivity) for maize and cowpea greatly varied across farms and crop types. Maize variety did not significantly impact the pLER of maize and cowpea. Water stress and nitrogen (N) stress simulated by the model were significant predictors of variations in pLER: maize pLER for aboveground biomass significantly decreased with increasing simulated water stress, and maize pLER for grain yield significantly decreased with increased simulated N stress. Yet, average LER remained above one, regardless of the water or N stress on maize, because of a greater contribution of cowpea to LER when water and N stress on maize was high. Late planting was found to exacerbate maize water stress, while low total nitrogen in the top soil was significantly correlated with maize nitrogen stress. Conclusion: Our study reveals that the production benefits of maize-cowpea intercropping can be maintained, in conditions of high water and nitrogen stress in multi-year and multi-location on-farm experiments
Farm resilience to climatic risk. A review
Get PDFIncreasing our understanding of farm resilience drivers to climate-related risks is critical for designing innovative farm systems, especially for smallholders that are highly vulnerable to climatic hazards and expected to follow a pathway toward sustainable development. However, the literature is fragmented on the concepts and methods to measure farm resilience. Moreover, quantitative assessments of options to enhance farm resilience to climate risks are scarce. Resilience can be defined as the ability of a system to recover, reorganize and evolve following external stresses and disturbances. Such definition can be applied to farm systems. In this study, we systematically reviewed how changes in resilience-enhancing attributes (reserves, openness, modularity, tightness of feedbacks and diversity) impacted farm performance and resilience to climate-related risks, with a specific attention to smallholder farms. Our analysis showed that reviewed studies assessed farm resilience using the agricultural and economic dimensions of performance, often excluding the socio-environmental dimensions. To assess performance, the average value of indicators was most commonly employed, sometimes combined with variability metrics or the probability of exceeding a critical threshold. Improving one resilience attribute increased one dimension of farm performance for a given metric in most of the studies, but some studies showed the opposite effect. The lack of comprehensive assessments exploring different attributes and their impact on several dimensions of performance using diverse metrics prevents a robust conclusion on how to improve farm resilience to climate-related risks. Therefore, we recommend to pay more attention to quantitative assessments of farm resilience, including a systematic investigation of the temporal variability of performance and the socio-environmental dimensions of performance. Finally, we emphasize the need to focus on the recovery of smallholder farms after a disturbance, with the goal of achieving growth in farm performance rather than simply reverting to their current state of food insecurity and poverty
Forage production in West Africa: Systematic review of advances, challenges, and perspectives for resilient agropastoral systems
Get PDFForage production in West Africa is essential for the region's agricultural economies and livestock systems but is greatly affected by climate variability, land degradation and increasing demographic pressures. Understanding current advances, challenges and perspectives is crucial to promoting sustainable agriculture, strengthening the resilience of livestock systems and improving the economic and social well-being of rural communities. An analysis of 169 published documents on natural and artificial pastures identified 488 forage species consumed by livestock, of which 301 herbaceous species and 187 woody species. Despite such vast diversity very few forage species, local or exotic, are integrated into production systems. Cultivated herbaceous species are selected for their agronomic qualities, nutritional value and digestibility, palatability, geographical origin, local availability of strains or seeds, drought and grazing resistance, and the ability to control invasive species. For legumes, their capacity to enrich soils is an additional criterion. Herbaceous species are primarily grown in monocultures, while legumes can be combined with other crops to maximize yields. In order to ensure sustainable and resilient forage production in West Africa, it is essential to integrate adapted local forage species, promote agroecological practices and strengthen the capacities of producers to address growing climatic and socio-economic challenges
Building a climate resilient Robusta coffee agroforestry system in Uganda: A research perspective
No full textClimate change may impose severe challenges to coffee farmers to maintain agricultural production levels especially in smallholder farmers, who produce 90% Uganda's coffee. In Uganda, Robusta coffee, which accounts for 80% of the total coffee production is predicted to be significantly affected. Climate adaptation and mitigation measures are required to moderate some of the worst predicted scenarios. Agroforestry has been highlighted as a cost-effective and sustainable strategy for modulating the effects of climate change in coffee farms given its contribution to carbon sequestration, reducing greenhouse gas emissions, diversification of tree and forest products, and reduction in the susceptibility of land-use systems to extreme weather events, among others. However, various research gaps need to be addressed, for deriving optimal benefits from agroforestry for climate change adaptation and mitigation in coffee. Paradoxically, while nearly all Robusta coffee is historically conducted using agroforestry methods, the growing negative view of the role of trees, especially the possibility of shade tree species serving as a reservoir for pests calls for concerted research efforts to guide the promotion of agroforestry methods to curb the development of monocultures. The review, therefore, highlights; (i) current knowledge relating to agroforestry tree choice, (ii) knowledge on above/below-ground interactions between trees and Robusta coffee from plot to landscape scales, and (iii) research areas that need to be addressed for building climate resilient Robusta coffee agroforestry (CAF) systems. Selecting appropriate agroforestry tree species and managing above and below-ground resources appear to be key factors for optimizing Robusta coffee production, but most of the information is missing in the context of Uganda's Robusta coffee-agroforestry systems. In the face of climate change that is likely to affect the biophysical environments and social structures, approaching the research activities through living laboratories, to collaboratively co-create, develop, and test new technologies, products and services in real-life environments could yield more practical solutions
Pounded yam: Scientific Report on Textural (extensibility) of yam population at CIRAD in Year 2025 at Guadeloupe
No full textIn this report, the extensibility texture of 20 pounded yam samples produced from Dioscorea alata varieties in Guadeloupe in Year 2025 were reported. The pounded yam samples were produced under standard conditions and analysed for the extensibility texture using a Kieffer dough extensibility (KDGE) rig. Dry matter of the fresh yam tubers was also determined. Results showed that the KDGE parameters (extensogram peak force, extensibility and extension area) were discriminant, especially the Extensogram peak force textural parameter. The PCA and hierarchical clustering distinguished the extensibility among the genotypes. For instance, varieties such as Ti-Violet, A9, and A14 had high extensibility, while varieties such as 74F, Dou, A39 and Evolution had poor extensibility. No significant correlations was found between dry matter of fresh yam and the extensibility parameters. There were some similarities and differences between the spatial placements of the same genotypes analysed in both Years 2025 and 2024 on a PCA. These information may be useful for breeders in selection of varieties for breeding improved varieties with consumer-preferred quality, and to understand the effect of harvest years on the extensibility texture or DM of Guadeloupian yam genotypes
Changing the decision context to enable social learning for climate adaptation
Get PDFSuccessful adaptation often involves changes to the decision context to enable new ways of thinking and acting on climate change. Using 16 adaptation initiatives the authors were engaged with, we analysed how and why decision contexts changed to identify ways to improve adaptation as a process of collective deliberation and social learning. We used the scope of the adaptation issue and governance arrangements to classify initiatives into four types and scored changes in the decision context using three frameworks: (1) the values, rules and knowledge (VRK) perspective to identify changes to adaptation decision-making; (2) the five dimensions of futures consciousness to identify the building of adaptation capabilities and (3) the social learning cycle to reveal evidence of reflexive learning. Initiatives using novel governance arrangements for discrete problems ('problem governance') or complex, systemic issues ('systems governance') scored highest for influences of VRK, futures consciousness and the social learning cycle on the decision context. Initiatives using existing management for discrete problems ('problem management') scored moderately for change in the decision context, while those using existing management for systemic issues ('systems management') scored low because change was often impeded by existing rules. All three frameworks influenced decision contexts in systems governance initiatives. Problem governance initiatives revealed interactions of VRK and futures consciousness but limited influence of VRK on the social learning cycle. Scope and governance arrangements differ with the adaptation issue and initiatives adapt over time: some small-scale ones became more systemic, developed novel governance arrangements and changed the decision context. Our findings do not show that some adaptation initiatives are better or more transformative than others; just that their scope and appropriate governance arrangements are different. This questions the notion that successful adaptation requires building generic transformative adaptation approaches and capabilities. There is a diversity of arrangements that work. What is important is to align the approach to the adaptation problem. We suggest two directions for improving adaptation initiatives: first, by influencing how they can shift between problem and systems focus and between standard management and novel governance, and secondly, by using methods to diagnose and direct change in the decision context
From pond to lowland scale, a systemic approach to better understanding small-scale rice-fish farming dynamics: Case study in Guinea
Get PDFContext: Rice-fish farming supports rural livelihoods in Guinea, but practices and outcomes vary widely due to differences in environmental conditions and market access. These disparities affect farmers' ability to adopt advanced aquaculture techniques, highlighting the need for context-specific approaches. Objective: This study explores the practices, constraints, and income contributions of rice-fish farming systems in Guinea, with a focus on the drivers of technical adoption and their effects on household livelihoods. Methods: A census of 1942 rice-fish farmers was combined with in-depth monitoring of 36 production cycles from 16 farms across three agro-ecological zones. Analyses included descriptive statistics, Kruskal-Wallis tests, mass balance, labor productivity calculations and qualitative analysis of semi-structured interviews. Market accessibility was identified as a significant influencing factor through statistical association with fish prices and practice adoption, and interpreted in light of qualitative information such as proximity to regional markets and the presence of wholesale fish buyers. Results and conclusions: Although farmers generally understand fish farming principles, only 59 % use H. fasciatus and 30 % adopt monosex tilapia. Many recycle small fish as fingerlings, limiting growth potential. Rice-fish farming contributes 18 % of household income, on par with rice (22 %) and plantation crops (21 %). In peri-urban areas, better market access encourages the adoption of advanced practices, leading to higher prices (25,000 GNF/kg vs. 16,000–20,000 elsewhere). In contrast, savannah farmers face challenges such as water scarcity and poor market connectivity, often integrating dry-season horticulture into ponds. Significance: The study highlights farmers' adaptability in developing context-specific practices. It underscores the need for tailored support to enhance the sustainability and resilience of rice-fish farming systems in Guinea
