Severe Drought Periods Research Articles

Influence of Hamoun Lakes' dry conditions on dust emission and radiative forcing over Sistan plain, Iran

Proximity to large desert areas, 120-day winds in Sistan, runs of severe drought periods, and control of the inflowing upstream waters have led to the drying up of Hamoun Lakes. These factors have transformed the Sistan plain into one of the most active sources of dust emission in southwestern Asia. Accordingly, the present study relied on a framework of spatio-temporal modeling to evaluate the effects of water body changes on dust emission and its climatic feedback across the Sistan plain. The research used remote sensing indices based on the long-term archive of Landsat 5, 7, and 8 data in the 1990–2021 period. The WRF-Chem model was applied under three scenarios including unchanged, 50%, and 100% drying of water bodies in two modes of with and without dust aerosol simulation and their atmospheric radiative feedbacks. The results show that with the drying of water bodies, dust emission increases by an average of about 40% (up to 80%). These conditions affect the radiative forcing of dust aerosol, including intensification of cooling/heating due to the reduction/increasing of shortwave (SW) radiation perturbation on average from −14 to −34 W/m2 at the bottom of the atmosphere (BOA) and from 0.9 to 2.1 W/m2 at top of the atmosphere (TOA). Additionally, these condition leads to the intensification of heating due to the increase in longwave (LW) radiation at BOA and TOA from 8.9 to 15 W/m2 and from 4.3 to 7.7 W/m2, respectively. Therefore, it can be acknowledged that in the 1990–2021 period, the drying of Hamoun Lakes has intensified the surface cooling by reducing net radiation (SW + LW) at the surface.

Total and chloroplast proteins of the leaves of cultivated, population and wild sunflower varieties cultivated under thermic stress

Sunflower (Helianthus annus L) cultivation is affected by periods of severe drought that affect the growth and yield of sunflower crops. Wild sunflower species have brought many agronomically important traits to cultivated sunflower by quickly allowing them to undergo biotic and abiotic changes in their environment. Plants have developed several mechanisms that would enable them to tolerate high temperatures related to thermotolerance at the biochemical and metabolic levels. The present study aimed to highlight the variability of total and chloroplast proteins extracted from the wild and populations of sunflower leaves grown under different thermal stresses. The total proteins extracted from controlled and thermic stress leaves, characterized by SDS page were similar except polypeptides of molecular weight (MW) 42 kDa, 35 kDa, 31 kDa and 13.5 kDa which showed variability of sunflower varieties studied. Under thermic stress, the MW of chloroplast proteins was similar in the H petiolaris fallax and H praecox runyonni varieties. The protein markers of wild sunflower species revealed in response to thermal stresses contribute to the improvement of sunflowers in the face of environmental challenges.

Trapped between drowning and desiccation: Riverine plants under hydropeaking

Hydropeaking is part of hydropower production. The discontinuous release of turbined water during hydropeaking generates sudden rise and falls of the water levels, as well as extended droughts. These artificial flow fluctuations impose challenging growing conditions for riverine vegetation. In order to identify vulnerable/resistant plant species to hydropeaking and to evaluate the impact of contrasting hydropeaking scenarios (simplified (i.e., sudden deep floods, frequent soil saturation and drought) and real-life, power plant-induced scenarios), we measured germination, survival, and morphological and physiological attributes of a selection of 14 plant species commonly found along riparian areas. Species were subject to different hydropeaking scenarios during three months (vegetative period) in the field and in a greenhouse. Half of the species performed worse under hydropeaking in comparison to the control (e.g., less germination and biomass, lower growth rates, reduced stem and root length, physiological stress) but none of the tested hydropeaking scenarios was clearly more disruptive than others. Betula pubescens, Alnus incana and Filipendula ulmifolia showed the largest vulnerability to hydropeaking, while other species (e.g., Carex acuta) were resistant to it. Both in the field and in the greenhouse, plants in perturbed scenarios accumulated more 13C than in the control scenario indicating limited capacity to perform 13C isotope discrimination and evidencing plant physiological stress. The highest 13C abundances were found under drought or flooding conditions in the greenhouse, and under the highest hydropeaking intensities in the field (e.g., Betula pubescens). Our results suggest that any hydropeaking scheme can be equally detrimental in terms of plant performance. Hydropeaking schemes that combine periods of severe drought with long and frequent flooding episodes may create a hostile environment for riverine species. Further research on “hydropeaking-tolerant” plant traits is key to draw the boundaries beyond which riverine species can germinate, grow and complete their life cycle under hydropeaking.

Sex and tree rings: Females neither grow less nor are less water-use efficient than males in four dioecious tree species

Females of woody dioecious species usually expend more resources on reproduction than males. Therefore, it is expected that females incur greater costs of reproduction than males, and, as a result, trade-offs between reproduction and growth should emerge. The aim of this study is to test those hypotheses by analyzing the differences between genders regarding radial growth (basal area increment) and wood carbon isotope composition (δ13C), a proxy of water-use efficiency. We compared these two variables in males and females of four dioecious tree species inhabiting drought-prone Mediterranean sites in Spain (Pistacia terebinthus, Ilex aquifolium, Juniperus thurifera and Ailanthus altissima). We analyzed the influence of sex on the radial growth patterns throughout the tree life considering the growth stage of individuals, the differences in the response of genders to climate variables (air temperature, precipitation and drought severity), and the δ13C during a severe drought period. One site was studied for each species and 21–33 trees per species were sampled in each site. No differences in growth were found between genders for any of the four species throughout their life span. No significant interactions between gender and precipitation were found, although A. altissima males were more responsive to summer (June-July) temperature. No differences in δ13C were found between genders excepting for P. terebinthus, indicating that the males of this species show a less efficient water use during drought events than the females. These results do not support the broad assumption that females of woody dioecious plants show lower growth and are less water-use efficient than males or that they respond differently to precipitation variability, except for P. terebinthus during drought events. Further analyses could be performed in other dioecious species inhabiting seasonally dry regions to confirm or reject our conclusions.

Tetraploidy Confers Superior in vitro Water-Stress Tolerance to the Fig Tree (Ficus carica) by Reinforcing Hormonal, Physiological, and Biochemical Defensive Systems.

The fig tree is a well-adapted and promising fruit tree for sustainable production in arid and semi-arid areas worldwide. Recently, Iran’s dryland fig orchards have been severely damaged due to prolonged severe and consecutive drought periods. As emphasized in many studies, ploidy manipulated plants have a significantly enhanced drought tolerance. In the current study, we compared the induced autotetraploid explants of two fig cultivars (‘Sabz’ and ‘Torsh’) with their diploid control plants for their water stress tolerance under in vitro conditions using different polyethylene glycol (PEG) concentrations (0, 5, 10, 15, 20, and 25%). After 14 days of implementing water stress treatments, the results revealed that both tetraploid genotypes survived at 20% PEG treatments. Only ‘Sabz’ tetraploid explants survived at 25% PEG treatment, while both diploid control genotypes could tolerate water stress intensity only until 15% PEG treatment. The results also demonstrated that the tetraploid explants significantly had a higher growth rate, more leaf numbers, and greater fresh and dry weights than their diploid control plants. Under 15% PEG treatment, both tetraploid genotypes could maintain their relative water content (RWC) at a low-risk level (80–85%), while the RWC of both diploid genotypes drastically declined to 55–62%. The ion leakage percentage also was significantly lower in tetraploid explants at 15% PEG treatment. According to the results, these superiorities could be attributed to higher levels of stress response hormones including abscisic acid, salicylic acid, and jasmonic acid at different PEG treatments, the robust osmotic adjustment by significantly increased total soluble sugar (TSS), proline, and glycine betaine contents, and augmented enzymatic defense system including significantly increased superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione peroxidase (GPX) activities in tetraploid genotypes, compared to their diploid control genotypes. Consequently, the current study results demonstrated that the ‘Sabz’ tetraploid genotype had a significantly higher water stress tolerance than other tested genotypes.

Exploring the temporal patterns and crisis-related risk factors for population displacement in Somalia (2016-2018)

IntroductionOver the past 30 years, south-central Somalia, Puntland (north-east) and Somaliland (north-west) have experienced recurring drought- and conflict-related crises. By the end of 2018, the number of internally displaced persons (IDPs) in the region had reached 2.6 million; most were displaced to larger towns under government control, where humanitarian assistance was more accessible. Understanding the drivers of crisis-related displacement can provide insight into how responses can best manage and respond to displacement to prevent downstream morbidity and mortality. We aimed to explore the temporal patterns and crisis-related risk factors for population displacement in Somalia from 2016 to 2018, a period of severe drought. MethodsWe conducted an ecological study of secondary panel data stratified by district and month. The study population included all people in the region from 2016 to 2018. The outcome was defined as the number of new out-migrating internally displaced persons (IDPs) per district-month. Exposure variables included armed conflict, rainfall, food insecurity and food security services. Lags at one, two and three months were generated to explore possible delayed effects. All univariate and multivariate analyses were conducted using negative binomial regression models with mixed effects incorporating the district as a random effect. ResultsFrom 2016 to 2018, the proportion of IDPs increased from 9% to 25% in Somalia, Puntland and Somaliland. We observed strong associations between IDP out-migration rate and failed rains at a three-month lag, food insecurity at a one-month lag, and the presence of therapeutic food services with no lag. IDP out-migration rate was not associated with armed conflict intensity, and cash- and rations-based food security services. DiscussionThis study identified temporal, and socially and biologically plausible associations between key crisis-related risk factors and displacement in Somalia. The findings suggest a sequence of events spanning a few months, where failed rains and consequent food insecurity likely prompted early population out-migration to larger urban centers where humanitarian services were more accessible. The presence of therapeutics-based food security services could represent a more general correlate of crisis severity and the decision to migrate.

Conserving for the common good: Preferences for water conservation policies during a severe drought in Northern California

During the 2011–2017 drought in California, water providers used a variety of demand-side management (DSM) policies to successfully reduce water consumption by over 20%. Unfortunately, because utilities used numerous conservation policies simultaneously, little is known about support for specific policies—specifically, an untested water-budgeting policy wherein utilities gave households an allotment of water and charged higher prices for water used in excess of the budget. California recently legislated mandatory long-term reductions in water usage. It is therefore critical to obtain a better understanding of which policies, including water budgeting, have strongest public support, and to understand how the drought experience changed residents' water use behaviors, attitudes, beliefs, habits, and personal capabilities surrounding conservation. This work surveyed individuals residing in northern California, the “North State,” during a period of severe drought. We used best-worst scaling to determine households’ preferences for DSM policies; asked households how their water use behaviors changed; and evaluated psychological attitudes toward drought and water conservation. Results show the vast majority of households changed their water use behaviors during the drought. Over two-thirds of respondents never exceeded their water budgets and said they would continue to conserve after the state lifted conservation requirements. Respondents preferred water budgets relative to more familiar DSM policies, a result with implications for forecasting future water demand. Last, our survey finds only minor differences in policy preferences for respondents with different demographics and attitudes toward water use, even for variables (e.g., income) that previous literature has found to have disparate welfare effects across users. • A majority of Californians changed their water-use behaviors during severe drought. • Northern California residents support using novel water budgets over voluntary conservation or watering restrictions. • Sociodemographic/psychological differences had little effect on conservation support.

Exploring seasonal variation in the faecal glucocorticoid concentrations of African elephants (

Context The wide-ranging movement of African elephants (Loxodonta africana) is largely driven by the spatio-temporal distribution of water and forage, and often leads to their travelling outside of formally protected areas. With an increase in drier periods predicted across Africa due to climate change, it is critically important to understand how elephants physiologically respond to alterations in the availability and distribution of resources. Aims We assessed variation in the adrenal activity of elephants living in Kenya’s Tsavo East National Park between wet and dry seasons, as well as among individuals found in Tsavo East National Park and privately protected Rukinga Wildlife Sanctuary (part of the Kasigau REDD+ wildlife corridor) in the dry season, when the area experiences an influx of elephants in search of alternative resources. Methods We opportunistically collected fresh elephant faecal samples across the two seasons and locations for analysis of faecal glucocorticoid metabolite (fGCM, a proxy for stress) and nitrogen (Nf, an indirect measure of diet quality) concentrations. The Normalised Difference Vegetation Index (NDVI) was employed as an additional indicator of habitat quality. Key results In Tsavo East N.P. Nf and NDVI were both significantly lower during the dry season, indicating poorer habitat quality compared with the wet season. Although elephant fGCM concentrations tended to be higher in the dry season than the wet, the differences were not significant. There was no difference between elephant fGCMs measured in Tsavo East N.P. and Rukinga W.S. during the dry season, nor in habitat quality between the two locations. Conclusions Elephants living in Tsavo may be physiologically unaffected by (or adapt to) typical seasonal changes in habitat quality that could lead to nutritional stress; however, whether this is the case during extended periods of severe drought requires further investigation. Rukinga W.S. provides a safe haven of sufficient habitat quality for elephants searching for alternative resources during this period. Implications Extended dry periods are likely to become increasingly common in semiarid savannahs, and implications for wildlife must be closely monitored. Privately protected land outside formally protected areas plays an important role in conservation efforts, which should be considered when making land management plans.

Mapping burn severity in the western Italian Alps through phenologically coherent reflectance composites derived from Sentinel-2 imagery

Deriving burn severity from multispectral satellite data is a widely adopted approach to infer the degree of environmental change caused by fire. Burn severity maps obtained by thresholding bi-temporal indices based on pre- and post-fire Normalized Burn Ratio (NBR) can vary substantially depending on temporal constraints such as matched acquisition and optimal seasonal timing. Satisfying temporal requirements is crucial to effectively disentangle fire and non-fire induced spectral changes and can be particularly challenging when only a few cloud-free images are available. Our study focuses on 10 wildfires that occurred in mountainous areas of the Piedmont Region (Italy) during autumn 2017 following a severe and prolonged drought period. Our objectives were to: (i) generate reflectance composites using Sentinel-2 imagery that were optimised for seasonal timing by embedding spatial patterns of long-term land surface phenology (LSP); (ii) produce and validate burn severity maps based on the modelled relationship between bi-temporal indices and field data; (iii) compare burn severity maps obtained using either a pair of cloud-free Sentinel-2 images, i.e. paired images, or reflectance composites. We proposed a pixel-based compositing algorithm coupling the weighted geometric median and thematic spatial information, e.g. long-term LSP metrics derived from the MODIS Collection 6 Land Cover Dynamics Product, to rank all the clear observations available in the growing season. Composite Burn Index data and bi-temporal indices exhibited a strong nonlinear relationship (R2 > 0.85) using paired images or reflectance composites. Burn severity maps attained overall classification accuracy ranging from 76.9% to 83.7% (Kappa between 0.61 and 0.72) and the Relative differenced NBR (RdNBR) achieved the best results compared to other bi-temporal indices (differenced NBR and Relativized Burn Ratio). Improvements in overall classification accuracy offered by the calibration of bi-temporal indices with the dNBR offset were limited to burn severity maps derived from paired images. Reflectance composites provided the highest overall classification accuracy and differences with paired images were significant using uncalibrated bi-temporal indices (4.4% to 5.2%) while they decreased (2.8% to 3.2%) when we calibrated bi-temporal indices derived from paired images. The extent of the high severity category increased by ~19% in burn severity maps derived from reflectance composites (uncalibrated RdNBR) compared to those from paired images (calibrated RdNBR). The reduced contrast between healthy and burnt conditions associated with suboptimal seasonal timing caused an underestimation of burnt areas. By embedding spatial patterns of long-term LSP metrics, our approach provided consistent reflectance composites targeted at a specific phenological stage and minimising non-fire induced inter-annual changes. Being independent from the multispectral dataset employed, the proposed pixel-based compositing approach offers new opportunities for operational change detection applications in geographic areas characterised by persistent cloud cover.

Impact of Reduced Rainfall on Above Ground Dry Matter Production of Semi-natural Grassland in South Gloucestershire, UK: A Rainfall Manipulation Study

In the United Kingdom, agricultural grasslands cover 40% of the land area, make up 89% of the total agricultural area and are an important land use for ecosystem services and food security. Climate change predictions suggest that the United Kingdom will experience more frequent and severe periods of drought that may impact these grasslands. As part of the Drought Risk and You (DRY) project, a field experiment in which rain shelters reduced precipitation reaching the vegetation by approximately 50%, was set up in the South West of England. The experiment ran for 3 years, from October 2015 to October 2018. The study was carried out at two locations in the catchment of the Bristol River Frome. Both sites were species-rich semi-natural pastures that had received no inputs of fertilizer or herbicide for many years. Automatic weather stations recorded environmental conditions, especially rainfall, within the experimental area. The existing agricultural management regimes were approximated by cutting the vegetation in the plots, by hand, at the appropriate times of year. The effect of rainfall reduction on plant growth was assessed by biomass sampling. At both sites, the rainfall reduction treatment had only small effects on total above ground dry matter production (biomass). These effects were much smaller than the year-to-year variation in total biomass. Our results suggested that well-established permanent pastures in the South West of England were able to tolerate a 3-year period of reduced water supply. The observed year-to-year variation in biomass demonstrated how important the timing of dry weather is for biomass production, and this will be reflected in effects on yield and quality of hay.

Transcriptomic and Biochemical Analysis Reveal Integrative Pathways Between Carbon and Nitrogen Metabolism in Guzmania monostachia (Bromeliaceae) Under Drought.

Most epiphytes are found in low-nutrient environments with an intermittent water supply. To deal with water limitation, many bromeliads perform crassulacean acid metabolism (CAM), such as Guzmania monostachia, which shifts from C3 to CAM and can recycle CO2 from the respiration while stomata remain closed during daytime and nighttime (CAM-idling mode). Since the absorbing leaf trichomes can be in contact with organic (urea) and inorganic nutrients (NO3−, NH4+) and the urea hydrolysis releases NH4+ and CO2, we hypothesized that urea can integrate the N and C metabolism during periods of severe drought. Under this condition, NH4+ can be assimilated into amino acids through glutamine synthetase (GS), while the CO2 can be pre-fixated by phosphoenolpyruvate carboxylase (PEPC). In this context, we evaluated the foliar transcriptome of G. monostachia to compare the relative gene expression of some genes involved with CAM and the N metabolism when bromeliads were submitted to 7days of drought. We also conducted a controlled experiment with an extended water deficit period (21days) in which bromeliads were cultivated in different N sources (urea, NH4+, and NO3−). Our transcriptome results demonstrated an increment in the expression of genes related to CAM, particularly those involved in the carboxylation metabolism (PEPC1, PPCK, and NAD-MDH), the movement of malate through vacuolar membrane (ALMT9), and the decarboxylation process (PEPCK). Urea stimulated the expression of PEPC1 and ALMT9, while Urease transcripts increased under water deficit. Under this same condition, GS1 gene expression increased, indicating that the NH4+ from urea hydrolysis can be assimilated in the cytosol. We suggest that the link between C and N metabolism occurred through the supply of carbon skeleton (2-oxoglutarate, 2-OG) by the cytosolic isocitrate dehydrogenase since the number of NADP-ICDH transcripts was also higher under drought conditions. These findings indicate that while urea hydrolysis provides NH4+ that can be consumed by glutamine synthetase-cytosolic/glutamate synthase (GS1/GOGAT) cycle, the CO2 can be used by CAM, maintaining photosynthetic efficiency even when most stomata remain closed 24h (CAM-idling) as in the case of a severe water deficit condition. Thus, we suggest that urea could be used by G. monostachia as a strategy to increase its survival under drought, integrating N and C metabolism.

Identifying the Drought Impact Factors and Developing Drought Scenarios Using the DSD Model

Droughts have become increasingly severe and frequent due to climate change. Droughts cause water scarcity and various socio-economic issues. Therefore, it is necessary to address drought conditions water resource management policies. The drought characteristics within each administrative division need to be closely analyzed to support effective policy-making. A drought impact factor analysis using a drought scenario development (DSD) model, is presented in this study. The DSD model identifies the drought impact factor for each administrative division through the relationship between various hydrometeorological factors and drought indices, and constructs a drought scenario. The proposed model was applied to 167 administrative divisions in South Korea. Hydrological factors significantly impact droughts than meteorological factors in South Korea. Identified drought impact factors are analyzed based on spatio-temporal variability to recognize the features in various aspects of droughts. Changes in water demand and severe drought periods were considered for temporal variability. Administrative divisions were grouped into four zones based on the type of water demand, and zonally analyzed to examine spatial variability. Finally, a drought scenario based on the identified drought impact factor was constructed to present the probable drought conditions. Components of the drought scenario represent the constitution of water resources within an administrative division, and high and low levels of each component were combined. The constructed drought scenarios facilitate effective policy-making for managing water resources.

Cross-stress tolerance: Mild nitrogen (N) deficiency effects on drought stress response of tomato (Solanum lycopersicum L.).

Climate change will lead to more frequent and severe drought periods which massively reduce crop production worldwide. Besides drought, nitrogen (N)-deficiency is another critical threat to crop yield production. Drought and N-deficiency both decrease photosynthesis and induce similar adaptive strategies such as longer roots, reduction of biomass, induction of reactive oxygen species (ROS), and antioxidative enzymes. Due to the overlapping response to N-deficiency and drought, understanding the physiological and molecular mechanisms involved in cross-stresses tolerance is crucial for breeding strategies and achieving multiple stress resistance and eventually more sustainable agriculture. The objective of this study was to investigate the effect of a mild N-deficiency on drought stress tolerance of tomato plants (Solanum lycopersicum L., cv. Moneymaker). Various morphological and physiological parameters such as dry biomass, root length, water potential, SPAD values, stomatal conductance, and compatible solutes accumulation (proline and sugar) were analyzed. Moreover, the expression of ROS scavenging marker genes, cytosolic ASCORBATE PEROXIDASES (cAPX1, cAPX2, and cAPX3), were investigated. Our results showed that a former mild N-deficiency (2mM NO3 -) enhances plant adaptive response to drought stress (4days) when compared to the plants treated with adequate N (5mM NO3 -). The improved adaptive response was reflected in higher aboveground biomass, longer root, increased specific leaf weight, enhanced stomatal conductance (without reducing water content), and higher leaf sugar content. Moreover, the APX1gene showed a higher expression level compared to control under N-deficiency and in combination with drought in the leaf, after a one-week recovery period. Our finding highlights a potentially positive link between a former mild N-deficiency and subsequent drought stress response in tomato. Combining the morphological and physiological response with underlying gene regulatory networks under consecutive stress, provide a powerful tool for improving multiple stress resistance in tomato which can be further transferred to other economically important crops.

Evaluation of mutant rice genotypes for tolerance to high temperature

Rice (Oryza sativa L.) is planted in about a tenth of the arable area around the world and is the largest source of food energy for half of humanity. Climatic change with increasing frequency of severe and prolonged drought periods and significant increases in air temperature has affected global rice production. Therefore, generating mutant rice cultivars tolerant to high temperatures and low water supplies is of utmost importance. Advanced mutant rice lines which were derived from irradiated Amistad -82 and J-104 were evaluated in the field under high temperatures and low water supply conditions using Amistad-82 variety as control. The genotypes with the best and worst field performances were compared using physiological parameters such as cell membrane thermostability, pollen viability, lipid peroxidation, and peroxidase and catalase activity under high temperature conditions. Three mutant lines, 8852, 8552 and LP-12 showed high yielding under high temperatures and low water supplies conditions in the field and also showed better pollen viability, cell membrane thermo stability, lipid peroxidation and peroxidase than LP-16 mutant lines and the control cv. Amistad-82. These results show that the physical irradiation of seeds with protons followed by subsequent in vitro embryo culture using 2,4D may generate genetic variability for tolerance to high temperatures. The variation observed for the physiological and biochemical indicators evaluated could be used for the early selection of high temperature tolerant rice genotypes

Progress With Livestock Welfare in Extensive Production Systems: Lessons From Australia.

The extensive livestock production industries are vital to the national economy of Australia. Continuing improvements to extensively-raised livestock welfare is desirable, necessary and in some situations mandatory, if the social license for animal sourced food and fiber production is to continue sustainably. However, meeting increasingly high welfare standards is challenging. The changing climate in this millennium, has seen the occurrence of two of the most severe drought periods on record in Australia, resulting in complex welfare issues arising from unforeseen disease, trade and environmental catastrophes. The onset of the first drought coincided with an uncontrolled epidemic of ovine paratuberculosis. It ended just prior to a temporary ban on live export of tropical cattle to Indonesia that induced a major market failure and led to severe morbidity and mortality on some beef properties. The second drought period progressed in severity and culminated in the most extreme bushfires recorded, causing unprecedented levels of mortality, morbidity and suffering in farmed animals and wildlife. Temperature extremes have also caused periodic heat-associated or cold-induced hyopthermia losses, requiring increased vigilance and careful management to reduce both temperature-induced stress during transport and the high ovine peri-parturient losses traditionally observed in extensive sheep farming. Several issues remain controversial, including surgical mulesing of wool sheep to manage flystrike, and the continuing live export trade of sheep and cattle. However, in reviewing the increasingly complex welfare challenges for the extensive livestock population industries that are export trade dependent and remain vulnerable to welfare activism, it appears progress has been made. These include development of prescribed livestock welfare Standards and Guidelines and the introduction of the Exporter Supply Chain Assurance System (ESCAS) to address export concerns. Further, the sheep mulesing crisis led to improved producer welfare attitudes and practices, including pain management during aversive husbandry procedures that is now occurring globally. Finally, innovations in animal welfare surveillance and assessment, are additional encouraging signs that suggest improving change management of extensive farm animal welfare is occurring that provides lessons well-beyond Australian shores.

Evaluation of Cactus (Opuntia Ficus Indica) and Prosopis Juliflora-Based Rations on Performance of Red Masai Weaner Lambs in Kenya

The purpose of this study was to determine plausible pathways to combat feed scarcity and quality in dry lands using locally available and under-utilized feed resources. Red Maasaiweaner lambs were blocked on the basis of body weight and physiological condition. The treatment diets included pure rations of Cenchrusciliaris hay (control) and proportionally determined combinations of P. juliflorapod meal, spineless (O. ficusindica) Cactus leaf meal and C. ciliaris hay. Analysis of variance (ANOVA) methods were used to isolate significant treatment effects on Cactus (O. ficusindica) and P. juliflorabased feed rations. Coefficient of correlation was computed to assess whether there was relationship between the independent and dependent variables in the test rations. Sheep that received T 4 rations recorded the highest in vivo and in vitro nutrient digestibility (78 and 63% respectively). Faecal output was positively correlated to DM intake (r 2 =0.88, p<0.001), in vivo (r 2 =0.87, p<0.001) and in vitro feed degradability (r 2 =0.87, p<0.001). Faecal Nitrogen was negatively correlated (r 2 = -0.64, p<0.001) to these values. The high dry matter intake, in vitro and in vivo DM digestibility of Cactus (O. ficusindica) cladodes and P. juliflorabased supplementary rations authenticate their value as under-utilized drought-tolerant supplementary forages for livestock in the truncated landscapes of Kenya. Awareness creation and/or promotional campaigns of Cactus species and Prosopisjuliflora-based home-made rations (TMRs) formulation such as on-farm demonstrations, capacity building, value addition and conservation of these invasive tree species as supplementary feed for livestock during severe drought periods is recommended in this current study.

A multi-proxy reconstruction of the late Holocene climate evolution in the Kapsabet Swamp, Kenya (East Africa)

Multi-proxy high-resolution records relating to climate and dominant vegetation cover have been obtained from a peat deposit retrieved from the Kapsabet swamp in western Kenya. The 4-m long peat sequence provided a continuous sedimentation record spanning ca. 3023 cal yr BP to the present and is representative of the late Holocene changes in the relatively high-altitude part of the Lake Victoria catchment. Paleoenvironmental factors influencing peat formation and organic matter (OM) source inputs in Kapsabet were reconstructed based on total organic carbon, carbon accumulation rate, δ13C, δ15N, C/N ratio, and specific biomarker-based n-alkane ratios. The Kapsabet peat sequence was divided into five stages based on different climatic conditions: Stage 1 (3023–1670 cal yr BP) represents a progression from cool dry to wet conditions. Stage 2 (1670–1187 cal yr BP) is a relatively warm and wet period with increased productivity and high OM input. Stage 3 (1187–625 cal yr BP) represents gradual warming coeval to the late Holocene Medieval Warm Period. Stage 4 (625–188 cal yr BP) is a cool and wet period with high variability in precipitation and hydrological conditions representing the Little Ice Age. Stage 5 (188 cal yr BP to present) represents a relatively cool and wet period that coincides with the expansion of agriculture, particularly in the lowlands. The proxies indicate a progressive change from a forested landscape to an open woodland coeval to a decline in terrigenous inputs and the advent of more wet conditions. The climate on the highlands was less variable than in the lowlands, which underwent several periods of drought and intermittent wet conditions. The changes in the catchment coincided with the expansion of agriculture and land clearance marking increased human activities in the lowlands. Overall, the Kapsabet peat sequence tracks the regional climatic changes in East Africa and marks a promising sedimentary archive for palaeoclimate reconstruction from a region with a paucity of palaeoenvironmental and palaeovegetation histories.

How tree species, tree size, and topographical location influenced tree transpiration in northern boreal forests during the historic 2018 drought.

Trees in northern latitude ecosystems are projected to experience increasing drought stress as a result of rising air temperatures and changes in precipitation patterns in northern latitude ecosystems. However, most drought-related studies on high-latitude boreal forests (>50°N) have been conducted in North America, with few studies quantifying the response in European and Eurasian boreal forests. Here, we tested how daily whole-tree transpiration (Q, Litersday-1 ) and Q normalized for mean daytime vapor pressure deficit (QDZ , Liters day-1 kPa-1 ) were affected by the historic 2018 drought in Europe. More specifically, we examined how tree species, size, and topographic position affected drought response in high-latitude mature boreal forest trees. We monitored 30 Pinus sylvestris (pine) and 30 Picea abies (spruce) trees distributed across a topographic gradient in northern Sweden. In general, pine showed a greater QDZ control compared to spruce during periods of severe drought (standardized precipitation-evapotranspiration index: SPEI<-1.5), suggesting that the latter are more sensitive to drought. Overall, QDZ reductions (using non-drought QDZ as reference) were less pronounced in larger trees during severe drought, but there was a species-specific pattern: QDZ reductions were greater in pine trees at high elevations and greater in spruce trees at lower elevations. Despite lower QDZ during severe drought, drought spells were interspersed with small precipitation events and overcast conditions, and QDZ returned to pre-drought conditions relatively quickly. This study highlights unique species-specific responses to drought, which are additionally driven by a codependent interaction among tree size, relative topographic position, and unique regional climate conditions.

Modeling the Underlying Drivers of Natural Vegetation Occurrence in West Africa with Binary Logistic Regression Method

The occurrence of natural vegetation at a given time is determined by interplay of multiple drivers. The effects of several drivers, e.g., geomorphology, topography, climate variability, accessibility, demographic indicators, and changes in human activities on the occurrence of natural vegetation in the severe drought periods and, prior to the year 2000, have been analyzed in West Africa. A binary logistic regression (BLR) model was developed to better understand whether the variability in these drivers over the past years was statistically significant in explaining the occurrence of natural vegetation in the year 2000. Our results showed that multiple drivers explained the occurrence of natural vegetation in West Africa at p &lt; 0.05. The dominant drivers, however, were site-specific. Overall, human influence indicators were the dominant drivers in explaining the occurrence of natural vegetation in the selected hotspots. Human appropriation of net primary productivity (HANPP), which is an indicator of human socio-economic activities, explained the decreased likelihood of natural vegetation occurrence at all the study sites. However, the impacts of the remaining significant drivers on natural vegetation were either positive (increased the probability of occurrence) or negative (decreased the probability of occurrence), depending on the unique environmental and socio-economic conditions of the areas under consideration. The study highlights the significant role human activities play in altering the normal functioning of the ecosystem by means of a statistical model. The research contributes to a better understanding of the relationships and the interactions between multiple drivers and the response of natural vegetation in West Africa. The results are likely to be useful for planning climate change adaptation and sustainable development programs in West Africa.

Can hydrological drought be efficiently predicted by conceptual rainfall-runoff models with global data products?

The seasonally-dry tropics of northern Costa Rica are characterized by recurrent drought events with negative socio-economic impacts on a vulnerable population. Scarce hydroclimatic observational data constraints reasonable water management and often results in water scarcity issues.This study analyses hydrological drought situations using freely available Global Precipitation Products (GPP) and a Regional Climate Model (RCM) that drive a relatively simple, semi-distributed rainfall-runoff model (HBV-Light). Firstly, the GPP and observed rainfall were used to calibrate the model simulating streamflow dynamics. Secondly, drought detection and estimates of drought duration, intensity and severity were determined with a daily variable threshold approach. Thirdly, we developed future hydrological drought scenarios based on a RCM. Generally, the GPP CHIRPS (Climate Hazards Group InfraRed Precipitation with Station Data) resulted in the best streamflow simulations (KGE > 0.6) compared with the model driven by observed rainfall (KGE > 0.7). CHIRPS also correctly identified the observed streamflow drought periods of 1994, 1997-1998 and 2001-2002.Average observed streamflow drought severity was 27.9 mm compared to the CHIRPS-derived severity of 20.6 mm (error estimate of ±7.3 mm). The model in combination with global data can be successfully used to identify drought periods and their duration, but model uncertainty currently prevents from forecasting streamflow deficit with volume errors below 50%. The future hydrological drought scenario showed more severe drought periods between 2039-2041 and 2042-2043.This study responds to the need for drought assessments in the seasonally-dry tropics with scarce observations as a tool for adaptation to climate change and water resource management.