West Africa constitutes a hotspot region for both land use change and climate change. Land use change, and high climate variability in this region negatively affect tree growth dynamics, ecosystem functioning and services. In the present study, we assessed the impacts of climate variability on tree growth of Detarium microcarpum Guill. & Perr. and Tamarindus indica L., two Fabaceae woody species with high socio-economic significance in West Africa. In total, we collected 18 stem discs from dead trees of the two species in the South-Sudanian phytogeographic zone in Burkina Faso. The studied species showed well-defined growth ring-boundaries demarcated by marginal parenchyma bands. Cross-dating was successful within disc and within species, and enabled the construction of statistically robust tree-ring index chronologies. The chronologies spanned 45 years (1974 − 2019) and 30 years (1990 − 2019) for D. microcarpum and T. indica, respectively. We found a significant variation in tree growth rates (p-value < 0.05) between D. microcarpum (1.711 ± 0.491 mm year−1) and T. indica (2.613 ± 0.473 mm year−1). Pearson correlation analyses showed that the standard ring-width index for both species positively correlated with total annual precipitation amounts (p-value < 0.05) and major seasonal precipitation (p-value = 0.05). However, no significant correlation was found between ring-width index and temperature related variables. These findings support that precipitation controls tree growth of D. microcarpum and T. indica in the semi-arid savannas of West Africa. Consequently, a decrease in mean annual rainfall in West African region may negatively affect tree growth rate and stand dynamics of the studied species.
Tag: climate variability
The importance of tropical tree-ring chronologies for global change research
Tropical forests are vital to global carbon and water cycles, yet the effects of climate change on these systems remain poorly understood due to limited long-term data. This study compiles 492 tropical tree-ring chronologies to assess their potential in reconstructing climate variability and understanding the climate sensitivity of woody productivity. The analysis reveals that while tree-ring studies have expanded rapidly, they remain biased toward high-elevation and drier regions, with significant gaps in wetter climates and among angiosperms. The strongest climate signals are found in cooler, drier sites. Species-distribution modeling identifies untapped regions for future research. These findings highlight the value of tropical dendrochronology in global change science, offering insights into climate extremes, vegetation dynamics, and model validation.
Comparative efficiency evaluation of different clay pots versus bucket irrigation system under swiss chard (Beta vulgaris subspcicla) growers condition in Northern Ethiopia.
Rain-fed agriculture shares the largest crop production system in Tigray region. However, due to erratic nature of rainfall, crop production is always at a risk. For this reason crop production in the arid and semi arid regions of northern Ethiopia usually requires supplemental irrigation. In an effort to assist agricultural production under smallholder farmers, the Regional Bureau of Agriculture and Natural Resources has been looking for efficient and less costly irrigation methods. Although drip irrigation technology has been well known for its higher efficiency, its adoption was too slow due to its high initial cost and inadequate technical knowhow. At the moment, in some areas of Tigray farmers have started practicing locally made low cost clay pot irrigation technology. However, the water use efficiency and its economic viability under smallholder farmers were not adequately understood. The objectives of this study were thus to examine the economical viability and estimate the water use efficiency of clay pot irrigation technology and to evaluate the performance of different clay pot design for irrigating Swiss chard (the most common leafy vegetable crop in this region). In this research traditional pot maker was instructed to manufacture four different clay pot designs (imperforated bar type, imperforated round shape type, perforated bar type and perforated round types) which were used for assessing performance of clay pot for irrigating swiss chard. Performance tests were carried out based on economic and biomass water use efficiencies and cost benefit ratios under two groups of farmers (with and without land). The result showed that the imperforated bar shaped clay pots were found to be suited to grow Swiss chard. The water seeps out through the micro pores of the clay pots with relatively slow leaks and long surface wetting time and large area converge around the roots of plants. Contrarly, perforated clay pots leak the water fast through the macro and micro pores and have relatively short wetting time and small area coverage. On the other hand, the difference between imperforated bar and round types were simply the shapes of the pots which is to do with the area coverage along with the rows of the Swiss chard plant. Round types were not as suitable as bar type of the same capacity for row Swiss chard crops due to their small wetting area coverage compared to a similar volume with imperforated bar shaped clay pots type. The economic and biomass water use efficiency for the imperforated bar clay pot design was higher than that of the bucket irrigation system as well as other tested clay pots. The other advantages with imperforated bar clay pots over the bucket type is that the water source is inside the soil thus evaporation is almost nil and there is also less probability of occurrence of leaf disease due to watering and ultimately improving the biomass and economical water use efficiency. However, the technology was not as profitable as the bucket irrigation technique when considering the benefit-cost ratio (BCR) due to costs incurred for purchase of clay pots.
Vulnerability and adaptive capacity of smallholders in Ho Ho subwatershed, North-Central Viet Nam
Climate change and variability create large uncertainties for agricultural production and smallholders’ livelihoods. Understanding smallholders’ vulnerability and their adaptive capacity to these factors is the key to appropriate interventions to mitigate the impact of climate-related shocks and hazards. In Ho Ho sub-watershed, north-central Viet Nam, smallholders reported a high degree of exposure and sensitivity to climate change and variability owing to the frequency of weather-related extreme events, such as flooding and drought, during the last decade (2005–2014), with a concomitant impact on households and agriculture. When comparing up- and downstream communes, biophysical factors such as topography, land-use patterns and the presence of a hydropower plant in the downstream commune played important roles in creating differences in exposure, sensitivity and adaptive capacity between the two communes. The results showed that while the upstream commune was not more vulnerable to weather-related extreme events compared to the downstream, its adaptive capacity was much lower, making the upstream generally more vulnerable than the downstream commune. We concluded that serious effects of climate change and variability during the last decade were experienced by smallholders in Ho Ho sub-watershed. We recommend that while enhancing the adaptive capacity of smallholders can include improvement both on- and off-farm, growing trees is a solution for improving both the landscapes and smallholders’ resilience.
Gender-specific responses to climate variability in a semi-arid ecosystem in northern Benin
Highly erratic rainfall patterns in northern Benin complicate the ability of rural farmers to engage in subsistence agriculture. This research explores gender-specific responses to climate variability in the context of agrarian Benin through a household survey (n = 260) and an experimental gaming exercise among a subset of the survey respondents. Although men and women from the sample population are equally aware of climate variability and share similar coping strategies, their specific land-use strategies, preferences, and motivations are distinct. Over the long term, these differences would likely lead to dissimilar coping strategies and vulnerability to the effects of climate change. Examination of gender-specific land-use responses to climate change and anticipatory learning can enhance efforts to improve adaptability and resilience among rural subsistence farmers.