Winter Rainfall Zone Research Articles

The phylogenetically isolated South African endemic diving beetle Caperhantus cicurius (Fabricius, 1787): redescription and range extensions (Coleoptera, Dytiscidae, Colymbetinae)

New distribution records and a redescription are presented for Caperhantus cicurius (Fabricius, 1787), a diving beetle endemic to the Cape region of South Africa, which is only distantly related to other Afrotropical dytiscids. We show that the species is much more widely distributed than previously recognized and present details of occupied habitats for the first time. Caperhantus cicurius occurs throughout the winter rainfall zone in South Africa, from Namaqualand to the Eastern Cape Province, particularly in temporary waters in the Fynbos and Succulent Karoo biomes.

Large herbivore δ18O as a proxy for aridity in the South African winter and year-round rainfall zone

Abstract This study explores patterning in δ18O values of tooth enamel in contemporary African herbivores from mainly C3-dominated ecosystems. Evapotranspiration causes plants to lose H216O to a greater extent than H218O, leaving leaves enriched in 18O. In eastern Africa, ES species (evaporation-sensitive species: those obtaining water from food) tend to have more positive δ18Oenamel values than EI species (evaporation-insensitive species: those heavily dependent on drinking water); the magnitude of the difference increases with increasing aridity. We find the same pattern applies in the winter and year-round rainfall region of southern Africa, allowing us to use δ18Oenamel in fossil animals to examine paleo-aridity. We apply this approach to infer aridity at Quaternary fossil assemblages from present-day winter and year-round rainfall zones, including Elandsfontein (ca. 1–0.6 Ma), Hoedjiespunt (ca. 300–130 ka), and Nelson Bay Cave (23.5–3 ka). This analysis suggests that (1) at various times during the Pleistocene, Elandsfontein and Hoedjiespunt environments were wetter than last glacial maximum (LGM) to Holocene environments at Nelson Bay Cave (year-round rainfall zone); and (2) considered alongside other evidence from the year-round rainfall zone, wetter conditions across the Pleistocene–Holocene transition at Nelson Bay Cave suggests that climate changes at near-coastal sites may be out of phase with the adjacent interior.

Examining the effects of climate change and human impacts on a high-resolution, late Holocene paleofire record from South Africa's winter rainfall zone

Fire is central to the Cape Floristic Region's highly biodiverse and disturbance-adapted Fynbos Biome. However, prehistoric fire regimes, their ecological consequences, and their relationships with large-scale climate drivers and human activities remain poorly understood. Here, we use a high-resolution sedimentary charcoal record from Verlorenvlei, a coastal lake situated on the west coast, to interrogate links between fire, climate, and pastoralism in the Fynbos Biome. Our record has a robust chronology supported by 24 radiocarbon dates and provides a continuous sedimentary sequence spanning the last 4200 years, documenting fire activity before and after the local arrival of pastoralists in the Verlorenvlei area ∼1500 cal years BP. Fire at Verlorenvlei over the last 4200 years is variable, with relatively low activity until ∼2000 cal years BP, after which variable but generally higher fire activity occurs until the highest period of fire activity from ∼1450 to 1800 CE (∼500–150 cal years BP). The increase in fire activity ∼2000 years ago corresponds with a shift in the diatom assemblage at Verlorenvlei from marine towards brackish and freshwater species, reflecting increased precipitation derived from a strengthening of the southern westerly winds. The peak in fire activity beginning ∼1450 CE (∼500 cal years BP), near the onset of the Little Ice Age, tracks a second diatom-inferred strengthening of the westerly winds. Other southern hemisphere and Antarctic records further corroborate this increased westerly influence after ∼2000 years. Linear regression modeling on the fire record indicates that moisture availability is the primary driver of fire at Verlorenvlei, with little evidence that human populations influenced fire. Our reconstruction suggests that fire activity at Verlorenvlei is limited by moisture availability and that wetter conditions facilitate increased vegetation (i.e., fuel) and intensified fire at this otherwise fuel-limited site. This work has implications for management and conservation decisions in response to future predictions of a warmer and drier climate along South Africa's west coast.

Evolution of winter precipitation in the Nile river watershed since the last glacial

Abstract. Between 14.5 and 5 ka, the Sahara was vegetated owing to a wet climate during the African humid period. However, the climatic factors sustaining the “green Sahara” are still a matter of debate. Particularly the role of winter precipitation is poorly understood. Using the stable hydrogen isotopic composition (δD, where D stands for deuterium) of high molecular weight (HMW) n-alkanoic acids in a marine sediment core from the eastern Mediterranean, we provide a continuous record for winter precipitation in the Nile river delta spanning the past 18 kyr. Pairing the data with δD records from HMW n-alkanes from the same core, we show that HMW n-alkanoic acids constantly derived from the delta, while the HMW n-alkanes also received significant contributions from the headwaters between ∼ 15–1 ka when fluvial runoff enhanced. This enables us to reconstruct the evolution of Mediterranean (winter) and monsoonal (summer) rainfall in the Nile river watershed in parallel. In the delta, the Heinrich stadial 1 (HS1) evolved in two phases, with a dry episode between ∼ 17.5–16.0 ka, followed by wet conditions between ∼ 16–14.5 ka. Winter rainfall enhanced substantially between 11–6 ka, lagging behind the intensification of the summer monsoon by ca. 3 kyr. Heavy winter rainfall resulted from a southern position of the Atlantic storm track combined with elevated sea surface temperatures in the eastern Mediterranean, reinforcing local cyclogenesis. We show that during the green Sahara, monsoon precipitation and Mediterranean winter rainfall were both enhanced and infer that the winter rainfall zone extended southwards, delivering moisture to the Sahara. Our findings corroborate recent hypotheses suggesting that winter rains that extended southward were a crucial addition to the northward displacement of the summer monsoon in helping to sustain a green Sahara.

Non-flying mammal pollination in Massonia grandiflora

Pollination by small non-flying mammals occurs in Africa, Australia, Asia and the Neotropics. One hotspot is in the winter rainfall zone of the Cape Floral Region of South Africa. This phenomenon is known for a handful of plant lineages, of which one comprises geoflorous monocots including the tribe Hyacintheae of the Asparagaceae. Small mammal pollination has been documented for four members of the Hyacintheae. A further representative of this taxon, Massonia grandiflora, is hypothesized to be pollinated by small mammals as it shares floral characters with other plants adapted to small mammal pollinators. The study aims at the identification of the pollinators and the characterisation of the floral features of M. grandiflora as well as to experimentally test whether the plants’ nectar scent is an attractant to the flower visitors. With direct observations and video monitoring, we demonstrate the fitting between the head of elephant-shrews and rodents and the bowl-shaped flowers with protruding stigmas and styles as well as pollen transfer from the plants’ anthers on the animals’ body parts that made contact with the stigma. We experimentally show the transfer of pollen surrogates by elephant-shrews and rodents from the anthers via the animals’ fur onto the stigmas of conspecific flowers. Pollen loads on the animals’ snout and in their faeces represent indirect evidence for flower visits. Insects and birds were not observed as nectar consumers. Choice tests revealed that mice and elephant-shrews are attracted by nectar scent. We conclude that the fragrant nectar attracts mice and elephant-shrews as pollinators, whereas its bitterness and viscosity as well as the flowers’ visual crypsis might filter out insects (and birds) as less effective pollinators.

Understanding temporal and spatial distribution of intestinal nematodes of horses using faecal egg counts and DNA metabarcoding

This study reports the spatial and temporal distribution of ascarid and strongylid nematodes in Thoroughbred horses by age category across different climatic zones in Australia over an 18-month period. Faecal samples (n = 2046) from individual horses were analysed using the modified McMaster technique for faecal egg counts (FECs). Strongylids were identified using PCR-directed next-generation sequencing of the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA. Yearlings had the highest prevalence (82%) of strongyle eggs followed by weanlings (79%), foals (58%), wet mares (49%) and dry mares (46%). For Parascaris spp., foals had the highest prevalence (35%) followed by weanlings (21%) and yearlings (10%). The highest mean FECs for Parascaris spp. were observed in foals (525 eggs per gram [EPG] of faeces) while those for strongyles were in yearlings (962 EPG). Among horses that were classified as adults at the time of sampling, 77% (860 of 1119) of mares were low (i.e., <250 EPG) strongyle egg-shedders. Mean strongyle FEC counts were highest in the Mediterranean (818 EPG) followed by summer (599 EPG), winter (442 EPG), and non-seasonal (413 EPG) rainfall zones. Twenty-six nematode species were detected, with Cylicostephanus longibursatus (26.5%), Cylicocyclus nassatus (23.7%) and Coronocyclus coronatus (20.5%) being the most frequently detected species. Their richness and relative abundance varied with horse age, season and climatic zone. In addition, Strongylus equinus and Triodontophorus spp. (T. brevicauda and T. serratus) were also detected. This comprehensive study elucidates spatial (climatic zone) and temporal (i.e., seasonal) trends in prevalence and burdens of intestinal nematodes in Australian horses using non-invasive conventional and molecular methods. The information presented in this study is crucial for developing integrated management strategies to control horse parasites in farmed horses.

Prevalence and diversity of ascarid and strongylid nematodes in Australian Thoroughbred horses using next-generation sequencing and bioinformatic tools

The study presents the results of a cross-sectional survey to describe the epidemiology of ascarid and strongylid nematodes in horses, the impact of diverse climatic conditions on parasite diversity and the levels of faecal egg shedding in different age groups of managed Thoroughbred horses. Individual faecal samples (n = 1377) collected from 62 Thoroughbred farms across four climatic zones in Australia were analysed using the modified McMaster technique for faecal egg counts (FECs) and strongylid nematodes were identified utilising PCR-directed next-generation sequencing (NGS) of the second internal transcribed spacer of the nuclear ribosomal DNA (ITS-2). Across all age groups, the prevalence of ascarid and strongylid nematodes was 12% (95% confidence interval 10–14%) and 72% (70–74%), respectively. Based on strongylid FECs, yearlings had the highest prevalence (89%) followed by weanlings (83%), foals (79%), wet mares (61%), dry mares (59%) and stallions (54%). However, for Parascaris spp., foals had the highest prevalence (46%) followed by weanlings (32%) and yearlings (13%). The highest mean FECs for Parascaris spp. were observed in foals (418 eggs per gram [EPG] of faeces) while those for strongylids were in yearlings (1002 EPG). Of the adult horses (mares and stallions), 67% (489 of 729) and 11% (77 of 729) were low (i.e., ≤250 EPG) and moderate (i.e., 251–500 EPG) strongylid egg-shedders, respectively. Strongylid egg shedding varied across climatic zones, with the highest mean FECs in the summer rainfall (723 EPG) followed by non-seasonal rainfall (629 EPG), winter rainfall (613 EPG), and Mediterranean (606 EPG) rainfall zones. Twenty-three nematode species were detected using NGS, with Cylicostephanus longibursatus (28%), Cylicocyclus nassatus (23%) and Coronocyclus coronatus (23%), being the most abundant species. Three species of Strongylus (i.e., S. vulgaris, S. equinus and S. edentatus) were also detected. The nemabiome composition, species richness and relative abundance varied within horse age and between climatic zones. These empirical findings provide a comprehensive understanding of the prevalence of parasites within horse populations and the multifaceted factors that influence their occurrence, thereby allowing for the formulation of tailored strategies aimed at parasite control in domestic horses.

Linking upwelling intensity and orbital-scale climate variability in South Africa's winter rainfall zone: Insights from a ∼70,000-year hyrax midden record

The climate of Africa's southwestern Cape is characterised by a strongly seasonal winter precipitation regime, with late Quaternary climate variability generally considered to have been driven by the position of the southern westerlies. This paper presents a unique ∼70,000 year-long palaeoclimatic record from a rock hyrax midden from South Africa's winter rainfall zone, enabling the analysis of regional climate systems since the beginning of marine isotope stage 4. The data suggest that the last glacial period was relatively humid compared to the Holocene, likely due to cooler temperatures, more extensive Antarctic sea-ice extent and an equatorward displacement of the westerly storm track. However, orbital-scale climate variability associated with the 23 kyr precessional cycle primarily correlates with changes in upwelling intensity in the Benguela system, implying an important role for the blocking of tropical easterly flow in driving long-term climatic variability. These factors combined during glacial periods to significantly amplify rainfall seasonality in the southwestern Cape, bringing more winter rainfall via mid-latitude frontal systems, while reducing the proportion of summer rainfall, particularly during the glacial periods of the late Quaternary. The results therefore highlight the need to consider a complex suite of circulation systems and dynamics when inferring drivers of long-term environmental change in the region.

Carnivore stable isotopes as environmental integrators in southern African winter rainfall ecosystems

The study explores the effects of environmental and climatic variables on the δ13C, δ15N and δ18O values of carnivores from modern C3 dominated environments in South Africa. Stable isotope ratios of carnivores may reflect large-scale environmental patterns better than those of herbivores because carnivores integrate variation seen at lower trophic levels. To explore this further, we have analysed δ13C and δ15N in bone collagen and δ13C and δ18O in tooth enamel of 12 species of carnivores obtained mostly from game parks and nature reserves in the winter and year-round rainfall zones of southern Africa. Sampling localities span several vegetation types, with varying rainfall, temperature, etc. We developed regression models for carnivore δ13C, δ15N and δ18O against nine meteorological variables: mean annual precipitation, mean annual temperature, mean annual soil moisture stress, mean annual potential evapotranspiration, relative humidity, summer aridity index, winter concentration of rainfall, moisture index and water deficit. There were significant correlations between δ13Cenamel and δ13Ccollagen and eight out of nine of the meteorological factors tested; the strongest correlations were with mean annual soil moisture stress (MASMS) (δ13Cenamelr2(adj) = 0.69 and δ13Ccollagenr2(adj) = 0.66). δ18Oenamel showed significant correlations with mean annual precipitation, mean annual potential evapotranspiration, summer aridity index, water deficit, relative humidity and the moisture index, but the r2 values were low. δ15Ncollagen showed significant correlations with eight out of nine of the meteorological factors (r2 values up to 0.63); only summer aridity index was not significantly correlated). Correlations between consumer δ13C values and meteorological variables were stronger for carnivores than in a previously published study of herbivores from the same region; the opposite pattern was seen in δ18O. Carnivore δ13C and δ15N are therefore effective integrators of environments. Where sample sizes permit, carnivores may be better proxies than herbivores for palaeoenvironmental reconstruction.

Spatial heterogeneity in rain-bearing winds, seasonality and rainfall variability in southern Africa's winter rainfall zone

Abstract. A renewed focus on southern Africa's winter rainfall zone (WRZ) following the Day Zero drought and water crisis has not shed much light on the spatial patterns of its rainfall variability and climatological seasonality. However, such understanding remains essential in studying past and potential future climate changes. Using a dense station network covering the region encompassing the WRZ, we study spatial heterogeneity in rainfall seasonality and temporal variability. These spatial patterns are compared to those of rainfall occurring under each ERA5 synoptic-scale wind direction sector. A well-defined “true” WRZ is identified with strong spatial coherence between temporal variability and seasonality not previously reported. The true WRZ is composed of a core and periphery beyond which lies a transition zone to the surrounding year-round rainfall zone (YRZ) and late summer rainfall zone. In places, this transition is highly complex, including where the YRZ extends much further westward along the southern mountains than has previously been reported. The core receives around 80 % of its rainfall with westerly or north-westerly flow compared to only 30 % in the south-western YRZ incursion, where below-average rainfall occurs on days with (usually pre-frontal) north-westerly winds. This spatial pattern corresponds closely to those of rainfall seasonality and temporal variability. Rainfall time series of the core and surroundings are very weakly correlated (R2&lt;0.1), also in the winter half-year, implying that the YRZ is not simply the superposition of summer and winter rainfall zones. In addition to rain-bearing winds, latitude and annual rain day climatology appear to influence the spatial structure of rainfall variability but have little effect on seasonality. Mean annual rainfall in the true WRZ exhibits little association with the identified patterns of seasonality and rainfall variability despite the driest core WRZ stations being an order of magnitude drier than the wettest stations. This is consistent with the general pattern of near homogeneity within the true WRZ, in contrast to steep and complex spatial change outside it.

Spatial heterogeneity of 2015–2017 drought intensity in South Africa's winter rainfall zone

Abstract. The 2014–2018 drought over South Africa's winter rainfall zone (WRZ) created a critical water crisis which highlighted the region's drought and climate change vulnerability. Consequently, it is imperative to better understand the climatic characteristics of the drought in order to inform regional adaptation to projected climate change. In this paper we investigate the spatio-temporal patterns of drought intensity and the recent rainfall trends, focusing on assessing the consistency of the prevailing conceptual model of drought drivers with observed patterns. For this we use the new spatial subdivision for the region encompassing the WRZ introduced in our companion paper (Conradie et al., 2022). Compared to previous droughts since 1979, the 2014–2018 drought in the WRZ core was characterised by a markedly lower frequency of very wet days (exceeding the climatological 99.5th percentile daily rainfall – including dry days) and of wet months (SPI1&gt;0.5), a sub-seasonal attribute not previously reported. There was considerable variability in the spatial footprint of the drought. Short-term drought began in the south-western core WRZ in spring 2014. The peak intensity gradually spread north-eastward, although a spatially near-uniform peak is seen during mid-2017. The overall drought intensity for the 2015–2017 period transitions radially from most severe in the WRZ core to least severe in the surroundings. During 2014 and 2015, the drought was most severe at those stations receiving the largest proportion of their rainfall from westerly and north-westerly winds; by 2018, those stations receiving the most rain from the south and south-east were most severely impacted. This indicates an evolving set of dynamic drivers associated with distinct rain-bearing synoptic flows. No evidence is found to support the suggestion that the drought was more severe in the mountain catchments of Cape Town's major supply reservoirs than elsewhere in the core nor that rain day frequency trends since 1979 are more negative in this subdomain. Rainfall and rain day trend rates also exhibit some connections to the spatial seasonality structure of the WRZ, although this is weaker than for drought intensity. Caution should be applied in assessing South African rain day trends given their high sensitivity to observed data shortcomings. Our findings suggest an important role for zonally asymmetric dynamics in the region's drought evolution. This analysis demonstrates the utility of the spatial subdivisions proposed in the companion paper by highlighting spatial structure in drought intensity evolution linked to rainfall dynamics.

South African winter rainfall zone shifts: A comparison of seasonality metrics for Cape Town from 1841–1899 and 1933–2020

Mounting evidence across South Africa’s southwestern winter rainfall zone (WRZ) reflects consistent drying since ~ 1980, and projected trends suggest this will continue. However, limited evidence exists for changes in the region’s rainfall seasonality. To improve our understanding of these WRZ drying trends, especially within the context of Cape Town’s 2015–2017 “Day Zero” drought, it is necessary to explore long-term rainfall seasonality trends. Thus, we use the longest WRZ meteorological record from the South African Astronomical Observatory (SAAO) in Cape Town to investigate rainfall seasonality shifts during 1841–2020. Consistent with recorded poleward migrations of the subtropical high-pressure belt and mid-latitude westerlies, known drivers behind the drought and drying trends, calculated trends demonstrate strengthening of WRZ conditions, primarily from a later start-date trend leading to a shorter wet-season. Long-term drying trends are quantified for the wet and dry seasons; however, analysis of trend evolution reveals much variability, reflecting that drying has only persisted since ~ 1892. Comparative analyses of the first and last 59 years of 1841–2020 reveal a rainfall decline of almost 10% across both seasons—highlighting that the extreme “Day Zero” drought was not only driven by wet-season rainfall declines. Results demonstrate that these drying trends were consistently driven by a long-term decline in rain day counts and a more recent decline in average rainfall per rain day. Correspondence between our results and projected rainfall seasonality trends suggests the trends we quantified will likely continue; thus, improvements and continuation of existing water conservation and management strategies are imperative for Cape Town.

Constraining the Spatial Distribution of Tritium in Groundwater Across South Africa

AbstractTritium (3H) has become synonymous with modern groundwater and is used in a myriad of applications, ranging from sustainability investigations to contaminant transport and groundwater vulnerability. This study uses measured 3H groundwater activities from 722 sample locations across South Africa to construct a 3H groundwater distribution surface. Environmental covariables are tested using geostatistical analysis to constrain external controls on 3H variability, namely: (a) depth to groundwater, (b) distance from the ocean, and (c) summer versus winter rainfall proportion. The inclusion of covariables in the “fit” of residual variograms improved prediction variance significantly yet does not mitigate issues with sample density. The distribution of 3H in groundwater agrees well to expected controls, with proximal (&lt;100 km) coastal regions, winter rainfall zones, and greater depth to groundwater predicted to have lower 3H activities. Conversely, inland localities with shallower depth to groundwater and/or summer rainfall are predicted to have elevated 3H activities. Some 3H high and low anomalies cannot be explained by known phenomena and may simply be regions of variable recharge and/or longer isolated groundwater flow paths. Regions that receive modern groundwater recharge are more vulnerable to climate change as well as modern pollution. Less actively recharged groundwater may be more resilient to climate change yet represents a potentially nonrenewable resource for abstraction in South Africa. The application of 3H distributions in the assessment of hydrological resilience is pertinent to effective groundwater management studies.

Early Holocene greening of the Sahara requires Mediterranean winter rainfall

The greening of the Sahara, associated with the African Humid Period (AHP) between ca. 14,500 and 5,000 y ago, is arguably the largest climate-induced environmental change in the Holocene; it is usually explained by the strengthening and northward expansion of the African monsoon in response to orbital forcing. However, the strengthened monsoon in Early to Middle Holocene climate model simulations cannot sustain vegetation in the Sahara or account for the increased humidity in the Mediterranean region. Here, we present an 18,500-y pollen and leaf-wax δD record from Lake Tislit (32° N) in Morocco, which provides quantitative reconstruction of winter and summer precipitation in northern Africa. The record from Lake Tislit shows that the northern Sahara and the Mediterranean region were wetter in the AHP because of increased winter precipitation and were not influenced by the monsoon. The increased seasonal contrast of insolation led to an intensification and southward shift of the Mediterranean winter precipitation system in addition to the intensified summer monsoon. Therefore, a winter rainfall zone must have met and possibly overlapped the monsoonal zone in the Sahara. Using a mechanistic vegetation model in Early Holocene conditions, we show that this seasonal distribution of rainfall is more efficient than the increased monsoon alone in generating a green Sahara vegetation cover, in agreement with observed vegetation. This conceptual framework should be taken into consideration in Earth system paleoclimate simulations used to explore the mechanisms of African climatic and environmental sensitivity.

Two new species of Moraea Mill. (Iridaceae: Iridoideae) from the southern African winter rainfall area

Moraea atromontana Goldblatt & J.C.Manning and M. cistiflora Goldblatt & J.C.Manning (Iridaceae: Iridoideae: Irideae) are two recently discovered species of this African and Eurasian genus of some 233 species. Both are members of subg. Vieusseuxia, and narrow endemics of the southern African winter rainfall zone in the Western Cape, South Africa. Moraea atromontana from the Swartberg near Calitzdorp, with a solitary leaf and derived, 3-lobed inner tepals, is morphologically similar to M. algoensis Goldblatt and M. unguicularis Ker Gawl. but differs in its larger, white flowers with a distinctive dark blue streak on the tepal claws, inner tepal limbs with a laxly spreading central cusp and short, downcurved lateral lobes, and much longer filament column; and M. cistiflora from the middle slopes of the Waaihoek Mtns near Wolseley, stands out in the section in its bowl-shaped flowers with subequal inner and outer tepals, white perianth with dark central eye, relatively long filament column with broad, spreading style branches and crests, and long capsules.

Hydroclimate change in subtropical South Africa during the mid-Piacenzian Warm Period

The mid-Piacenzian Warm Period (mPWP, 3.264–3.025 Ma) of the Pliocene epoch has been proposed as an analog for future climate scenarios. Disagreement between the paleoenvironmental reconstruction and model simulations of the climate in subtropical regions for this period suggests that more investigation of the subtropical climate variability of the mPWP is needed. This study presents pollen, microcharcoal and benthic foraminifera oxygen isotope records generated from marine sediment cores of International Ocean Discovery Program (IODP) Exp. 361 Site U1479 from the Cape Basin offshore of South Africa for the period between 3.337 and 2.875 Ma. With an average sample resolution of 3 ka, this record represents the highest-resolution record of mPWP vegetation change from the region. Our results indicate that the vegetation during the mPWP was dominated by fynbos (species-rich heathy vegetation in the Cape Floristic Region) with variable proportions of Ericaceae. Moreover, the development of the Afrotemperate forest (tall, multilayered indigenous forests in South Africa) reflects shifts in the amounts of precipitation between winter and summer in the year-round rainfall zone. The vegetation variation is probably influenced by the latitudinal insolation gradient in response to precession forcing. Several glacials depicted by the benthic foraminifera oxygen isotope record were characterized by lower percentage values of Restionaceae, higher percentage values of ericoid fynbos and Afrotemperate forest. These events correspond well with cooler SE Atlantic sea surface temperatures driven by interactions of both atmospheric and oceanographic processes. The cooler sea surface temperatures attributed to Antarctic ice sheet expansion, reduced Agulhas leakage (heat and salt transfer from the Indian Ocean to the Atlantic Ocean) and/or intensified southern Benguela upwelling, resulted in less precipitation in the winter rainfall zone of South Africa.

Plant taphonomy, flora exploitation and palaeoenvironments at the Middle Stone Age site of Mwulu’s Cave (Limpopo, South Africa): an archaeobotanical and mineralogical approach

The interior regions of South Africa have had less attention devoted to archaeological research than coastal regions, and palaeoenvironmental studies are also more limited. As such, little is known about the interaction between human behaviours and past environments in these semi-arid regions. Here, we present an archaeobotanical and mineralogical study from the Middle Stone Age site of Mwulu’s Cave, Limpopo Province. Our study shows the importance of using taphonomical approaches prior to interpreting archaeobotanical assemblages, while provides with novel information on the plants used by ancient inhabitants of Mwulu’s. The grass phytolith composition is of environmental significance, where a shift from C4 Panicoideae to C3 grasses is observed in the last occupation event. This tentatively suggests a shift in rainfall regime, from summer rainfall conditions to an increase in winter rain, during Marine Isotope Stage 5b in the Polokwane region, or a decrease in rainfall seasonality. Although we are unable to chronostratigraphically associate this change in the plant composition, our study adds evidence in support of previous propositions for an expansion of the winter rainfall zone into the interior regions of South Africa.

Holocene variability in climate and oceanic conditions in the winter rainfall zone of South Africa—inferred from a high resolution diatom record from Verlorenvlei

ABSTRACTWe present a diatom record from a well‐dated 15.25 m composite sedimentary core from Verlorenvlei, a shallow coastal lake on the west coast of South Africa. We show that fluctuations in the diatom record occur in response to changes in sea level, ocean–atmosphere interactions and latitudinal shifts in the wind belts. During the early to mid‐Holocene, the system primarily responds to sea level changes. A marine community that favours high nutrients is evident, particularly during 9200–8000, 7420–7000 and 6200–5600 cal a bp, corroborating periods of Benguela upwelling linked to fluctuations in the southeast trade winds. Increases in bioproductivity (%TOC, C/N) and fresher‐water diatoms are associated with wetter conditions over the region and the northward migration of the southern westerly wind belt, most notably between 8000 and 7500 cal a bp and over the last 700 years. The latter trends are concomitant with changes in the extent of Antarctic sea ice and availability of moisture in southern South America. During the late Holocene, as sea levels stabilised to modern levels, climate variability is more strongly evident. The body of evidence further reveals the sensitivity of the region to high‐latitude atmospheric mechanisms, but also showcases the significance of the southeast trade winds.

Use of δ13C as water stress indicator and potential silvicultural decision support tool in Pinus radiata stand management in South Africa

Abstract: In this study, the carbon isotope ratio in tree rings was investigated as a potential measure of water availability and drought stress in Pinus radiata stands in South Africa. An understanding of water availability and its variation in space is fundamental to the implementation of increasingly site-specific management regimes that have the potential to improve stand productivity. Fourteen plantation compartments, situated on water shedding (convex) terrain were identified where reliable weather data existed and a water balance model could be run. This output was used to derive water stress indicators: (a) relative canopy conductance (gc/gcmax) and (b) the ratio of actual to potential evapotranspiration (ETa/ETp). The water stress indicators (calculated per year of growth) were related to δ13C values in five tree rings formed in the five years before mid-rotation thinning took place. The water balance model used adequately described soil water availability throughout each growing season and indicated that most severe stand water stress occurred during the summer months of the study period (November to April). The ETa/ETp ratio for this period as well as the relative canopy conductance proved to be good measures of water stress. The 5-year averages of the ETa/ETp ratios (taken over the driest 6 month period) ranged from 0.17 to 0.32 (winter rainfall zone) and 0.44 to 0.70 (all-year rainfall zone). The 5-year averages of ETa/ETp ratios could be accurately predicted (p< 0.0001; adjusted r2 = 0.83) with multiple regression using δ13C values in whole-wood samples (i.e., earlywood and latewood) and the site index of stands (where site index is the average height of the dominant 20% trees in the stand at base age 20). The δ13C values in tree rings across the planted range of P. radiata in South Africa can therefore be used to identify broad categories of water availability for purposes of increasingly site-specific silvicultural management.

Epidemiology of gastrointestinal nematodes of alpacas in Australia: II. A longitudinal study.

We conducted a longitudinal survey on 13 alpaca farms in four climatic zones of Australia to understand the epidemiology of gastrointestinal nematodes (GINs) of alpacas. A total of 1688 fresh faecal samples were collected from both sexes of alpacas from May 2015 to April 2016 and processed for faecal egg counts (FEC) and molecular identification of eggs using the multiplexed-tandem PCR assay. Based on egg morphology, the overall prevalence of GINs was 61% while that for strongyles was 53%. The overall mean FEC was 168 eggs per gram (EPG) of faeces, with the highest count of 15,540 EPG. Weaners had the highest prevalence (73%) and mean FEC (295 EPG) of GINs followed by tuis, crias and adults. Alpacas in the winter rainfall zone had the highest prevalence (68%) as well as FEC (266 EPG) followed by Mediterranean-type, non-seasonal and summer rainfall zones. Trichostrongylus spp. (83%, 89/107), Haemonchus spp. (71%, 76/107) and Camelostrongylus mentulatus (63%, 67/107) were the three most common GINs of alpacas across all climatic zones. The mixed-effects zero-inflated negative binomial regression model used in this study showed that it could help to design parasite control interventions targeted at both the herd level and the individual alpaca level. The findings of this study showed that the epidemiology of GINs of alpacas is very similar to those of cattle and sheep, and careful attention should be paid when designing control strategies for domestic ruminants co-grazing with alpacas.