Savannah Environment Research Articles

Differential patterns of nitrogen nutrition and growth cost of the indigenous Vachellia sieberiana and the introduced Chromolaena odorata in the savannah environment.

Vachellia sieberiana fixes atmospheric nitrogen (N) and distributes it back into ecosystems. We hypothesize that biological nitrogen fixation in this plant species is limited by competition from the invasive shrub, Chromolaena odorata. Competition would therefore result in the legume plant switching its limited nitrogen (N) sources in phosphorus-poor soils in savannah ecosystems when resources have to be shared. This study investigated the different patterns of N use and growth costs by a native and an introduced leguminous shrubby species. We propose that the two species sharing the same environment might result in competition. The competitive effect would induce in the indigenous legume to better utilize atmospheric-derived N modifying plant growth kinetics and plant mineral concentrations. Seedlings of V. sieberiana were cultivated in natural soil inoculum with low levels of phosphorus (mg L-1 ± SE) of 3.67 ± 0.88. The experiments were divided into two treatments where (i) seedlings of V. sieberiana were subjected to competition by cultivating them together with seedlings of C. odorata, and (ii) seedlings of V. sieberiana were cultivated independently. Although V. sieberiana was subjected to competition, the N2-fixing bacteria that occupied the nodules was Mesorhizobium species, similar to plants not subjected to competition. Total plant biomass was similar between treatments although V. sieberiana plants subjected to competition accumulated more below-ground biomass and showed higher carbon construction costs than plants growing individually. Total plant phosphorus and nitrogen decreased in seedlings of V. sieberiana under competition, whereas no differences were observed in percent N derived from the atmosphere (%NDFA) between treatments. The specific nitrogen utilization rate (SNUR) was higher in V. sieberiana plants subjected to competition while specific nitrogen absorption rate (SNAR) showed the opposite response. Vachellia sieberiana is highly adapted to nutrient-poor savannah ecosystems and can withstand competition from invasive shrubs by utilizing both atmospheric and soil nitrogen sources.

Characterization and comparison of poorly known moth communities through DNA barcoding in two Afrotropical environments in Gabon

Biodiversity research in tropical ecosystems-popularized as the most biodiverse habitats on Earth-often neglects invertebrates, yet invertebrates represent the bulk of local species richness. Insect communities in particular remain strongly impeded by both Linnaean and Wallacean shortfalls, and identifying species often remains a formidable challenge inhibiting the use of these organisms as indicators for ecological and conservation studies. Here we use DNA barcoding as an alternative to the traditional taxonomic approach for characterizing and comparing the diversity of moth communities in two different ecosystems in Gabon. Though sampling remains very incomplete, as evidenced by the high proportion (59%) of species represented by singletons, our results reveal an outstanding diversity. With about 3500 specimens sequenced and representing 1385 BINs (Barcode Index Numbers, used as a proxy to species) in 23 families, the diversity of moths in the two sites sampled is higher than the current number of species listed for the entire country, highlighting the huge gap in biodiversity knowledge for this country. Both seasonal and spatial turnovers are strikingly high (18.3% of BINs shared between seasons, and 13.3% between sites) and draw attention to the need to account for these when running regional surveys. Our results also highlight the richness and singularity of savannah environments and emphasize the status of Central African ecosystems as hotspots of biodiversity.

Gebel Ramlah\u2014a Unique Newborns\u2019 Cemetery of the Neolithic Sahara

Post-Pleistocene climatic improvement in the Northern Hemisphere after ca. 9550 BC allowed human populations to recolonize large parts of North Africa in what is today the Sahara Desert. In the Egyptian Western Desert, the beginnings of human occupation date as early as ca. 9300 BC. Occupation continued until the middle of the third millennium BC when final desertification of the area no longer afforded human occupation. The settlement of the Neolithic cattle and sheep/goat herders developed along with the rhythm of alternating wet and dry climatic oscillations. One of the areas occupied intensively during the early and middle Holocene was Gebel Ramlah. Pastoral populations established their settlements around the shores of a paleo-lake adjacent to a rocky massif, to exploit the local savannah environment. During most of the Neolithic, they buried their dead dispersed outside of their settlements. Only during the Final Neolithic (after ca. 4600 BC) did they place them exclusively in cemeteries. Of six Final Neolithic cemeteries investigated at Gebel Ramlah to date, one is entirely unprecedented, not only in North Africa but also globally at such an early date. For just under 200 years (ca. 4500–4300 BC), it served exclusively for the inhumation of infants who died around (perinate) or shortly after the time of birth (neonate). Thirty-two burial pits contained skeletal remains of 39 individuals, not only infants but also at least two adult females accompanied by perinates/neonates. Older children (> 3 years) were interred at a nearby cemetery that primarily comprised adults.

Fusing Landsat and MODIS data to retrieve multispectral information from fire-affected areas over tropical savannah environments in the Brazilian Amazon

ABSTRACTIn this study, the combination of surface reflectance products from Terra- Moderate Resolution Imaging Spectroradiometer and Landsat-Enhanced Thematic Mapper Plus sensors are explored through the Flexible Spatiotemporal DAta Fusion (FSDAF) algorithm within the framework of forest fire studies over tropical savannah environments. Thus, 60 fusion-derived images were generated from four spectral bands [red, near-infrared, shortwave infrared (SWIR1 and SWIR2)] and six spectral indices [normalized difference vegetation index, normalized difference moisture index, global environment monitoring index, soil-adjusted vegetation index, normalized burn ratio (NBR), and differenced normalized burn ratio (dNBR)] over two selected study sites. For all fusion processes performed, the actual Landsat images for the corresponding dates are available, which supports validation of the blended images. Additionally, integration of blended spectral indices in the immediate post-fire evaluation and the generation of fire severity were analysed. The blended bands presented correlation and Structure Similarity Index Measure (SSIM) values that were consistently higher than 0.819 and root mean square error values of less than 0.027, which confirms good accuracy levels obtained from the model. Similar correlation and SSIM accuracy levels were observed in the blended indices assessment for both study sites, which enables its values to be well-integrated for an analysis of the immediately post-fire date. However, the fire severity mapping from fused images needs to be carefully implemented since the dNBR index is generally less accurate than other blended indices. FSDAF fusion proved to be a useful alternative to retrieving multispectral information from savannah environments affected by fires.

Ichthyofauna of piedmont and savannah environments in the Casanare River drainage, Orinoco Basin, Colombia 

Currently, only 20 fish species have been recorded from the Casanare River, which is one of the main tributaries of the Meta River drainage. To characterize the fish assemblages of this river, samplings were carried out at 35 collecting stations in low and high water seasons of 2015. The results obtained, raised the number of fish species of the Casanare River drainage to 180, of which 41 are exclusive to the piedmont, 83 to the savannah and 56 are shared between both units; 19 species are endemic, 11 are migratory, and three are classified in one of the national threat categories. Three species were found to be undescribed and one represents a new record for the Orinoco River Basin in Colombia. This study fills the lack of information for the Casanare River drainage, highlights its importance as a potential area for biodiversity conservation and facilitates the decision-making process related to the management planning and conservation of the hydrographic basin

Range Extension and Behavioural Observations of the Recently Described Sheth's Dwarf Lemur (Cheirogaleus shethi)

Sheth's dwarf lemur, Cheirogaleus shethi, is a small, recently discovered nocturnal primate endemic to northern Madagascar. Unlike many other nocturnal lemurs, C. shethi lives sympatrically with morphologically similar species of its cryptic genus, making it difficult for biologists to determine its population density and distribution. Here, we present new data and observations of this species. During a series of rapid biodiversity assessments in the SAVA region of north-eastern Madagascar, we observed C. shethi in 10 different sites, 9 of which were not previously known to harbour C. shethi populations. More significantly, 2 of these sites, in Analamanara, were situated approximately 20 km south of the previously known southern extremity of this species' distribution. This represents a large increase in the previously limited geographic range of this species. Moreover, our relatively high encounter rates at these sites suggest that C. shethi population densities may be high. We also observed C. shethi in human-altered (e.g., vanilla plantations) and non-forest, savannah environments, suggesting that this species can tolerate disturbed habitats. Our findings therefore provide important additional information on the distribution of C. shethi populations and highlight the necessity of further study for the conservation of this species.

My experiences with Indigenist methodologies

AbstractTraditionally, geographic research and engagement with Indigenous communities have largely been developed within a western research paradigm and have historically been linked to colonial practices such as extraction and/or domination. The consequences of these research practices and paradigms have been the further marginalisation of Indigenous people globally. However, geographers are increasingly being influenced by a range of Indigenous scholars from both within and beyond the discipline who highlight the colonial foundations of geographic knowledge and the ongoing production of colonial relations, and who are calling for a decolonisation of knowledge through the use of Indigenist methodologies. After exploring this shift, this paper moves to a discussion of my engagement with research in Indigenous communities using Indigenist methodologies, including the emotions and thought processes that emerged during my own research journey, which led me to southern Guyana and the Makushi and Wapishana peoples who reside in the northern savannah environments of the Amazon basin. I conclude by sharing how I am continuing that journey using Indigenist approaches in my work in the Madre de Dios region of Peru, and by encouraging future scholars to challenge traditional geographic research methods.

Diurnal thermoregulatory responses in pregnant Yankasa ewes to the dry season in a tropical Savannah.

The study investigated concomitant effect of gestation and high ambient temperature under a tropical environment on rectal temperature (RT), respiratory rate (RR) and heart rate (HR) responses in Yankasa ewes. Twenty Yankasa ewes, consisting of ten pregnant and ten non-pregnant ewes, were used for the study. Ewes were synchronised and bred, such that each gestation phase coincided with different periods of the dry-seasons, early-gestation (cold/harmattan), mid-gestation (peak hot-dry) and late-gestation (late hot-dry). The RT, RR and HR were recorded thrice, 2days apart at middle of each gestation period at 06:00, 14:00 and 18:00 h, concurrently with dry- (DBT) and wet-bulb temperatures of the experimental pen. The DBT was positively correlated with RT, RR during the different gestation stages. The RT significantly (P<0.001) increased with the hour of day, regardless of the physiological status of the ewes, with peak at 14:00h. Values of RT and RR were higher (P<0.05) in pregnant than non-pregnant ewes at mid- and late-gestation, respectively. Mean RT was lower (P<0.001) at 06:00h in pregnant than non-pregnant ewes at early-gestation (cold-dry). The HR was (P<0.05) higher in pregnant than non-pregnant ewes during the different gestation phases. In conclusion, ambient temperature and gestation concomitantly modulate diurnal thermoregulatory responses of the ewes to hot-dry season. Adequate measures should be adopted to mitigate adverse impact of prolonged high RR on the dam and the foetus during the peak of ambient temperature prevailing in the tropical Savannah environment.

Messinian age and savannah environment of the possible hominin Graecopithecus from Europe.

Dating fossil hominids and reconstructing their environments is critically important for understanding human evolution. Here we date the potentially oldest hominin, Graecopithecus freybergi from Europe and constrain the environmental conditions under which it thrived. For the Graecopithecus-bearing Pikermi Formation of Attica/Greece, a saline aeolian dust deposit of North African (Sahara) provenance, we obtain an age of 7.37–7.11 Ma, which is coeval with a dramatic cooling in the Mediterranean region at the Tortonian-Messinian transition. Palaeobotanic proxies demonstrate C4-grass dominated wooded grassland-to-woodland habitats of a savannah biome for the Pikermi Formation. Faunal turnover at the Tortonian-Messinian transition led to the spread of new mammalian taxa along with Graecopithecus into Europe. The type mandible of G. freybergi from Pyrgos (7.175 Ma) and the single tooth (7.24 Ma) from Azmaka (Bulgaria) represent the first hominids of Messinian age from continental Europe. Our results suggest that major splits in the hominid family occurred outside Africa.

Scrubbing Up: Multi-Scale Investigation of Woody Encroachment in a Southern African Savannah

Changes in the extent of woody vegetation represent a major conservation question in many savannah systems around the globe. To address the problem of the current lack of broad-scale cost-effective tools for land cover monitoring in complex savannah environments, we use a multi-scale approach to quantifying vegetation change in Kruger National Park (KNP), South Africa. We test whether medium spatial resolution satellite data (Landsat, existing back to the 1970s), which have pixel sizes larger than typical vegetation patches, can nevertheless capture the thematic detail required to detect woody encroachment in savannahs. We quantify vegetation change over a 13-year period in KNP, examine the changes that have occurred, assess the drivers of these changes, and compare appropriate remote sensing data sources for monitoring change. We generate land cover maps for three areas of southern KNP using very high resolution (VHR) and medium resolution satellite sensor imagery from February 2001 to 2014. Considerable land cover change has occurred, with large increases in shrubs replacing both trees and grassland. Examination of exclosure areas and potential environmental driver data suggests two mechanisms: elephant herbivory removing trees and at least one separate mechanism responsible for conversion of grassland to shrubs, theorised to be increasing atmospheric CO2. Thus, the combination of these mechanisms causes the novel two-directional shrub encroachment that we observe (tree loss and grassland conversion). Multi-scale comparison of classifications indicates that although spatial detail is lost when using medium resolution rather than VHR imagery for land cover classification (e.g., Landsat imagery cannot readily distinguish between tree and shrub classes, while VHR imagery can), the thematic detail contained within both VHR and medium resolution classifications is remarkably congruent. This suggests that medium resolution imagery contains sufficient thematic information for most broad-scale land cover monitoring requirements in heterogeneous savannahs, while having the benefits of being cost-free and providing a longer historical archive of data than VHR sources. We conclude that monitoring of broad-scale land cover change using remote sensing has considerable potential as a cost-effective tool for both better informing land management practitioners, and for monitoring the future landscape-scale impacts of management policies in savannahs.

Palaeoenvironments and the origin of hominid bipedalism

It has long been accepted that hominids emerged during the Pliocene in a savannah environment in which a terrestrial quadruped gradually developed bipedal adaptations. However, data from the Late Miocene (i.e. 7–7.5 Ma), including detailed palaeontological and biogeochemical studies, suggest that our earliest Upper Miocene ancestors inhabited well-wooded to forested environments where they could have spent a certain amount of time in the trees. A plausible type of ecosystem in which upright posture and bipedal locomotion could have emerged is represented by Miombo Woodland, in which vertical arboreal supports predominate and trees are separated from each other by gaps. Subsequently hominids dispersed into the Savannah as accomplished bipeds, but retained the ability to climb trees. This scenario is compatible with the postcranial anatomy of Australopithecus, including its femoral elongation, body proportions, manual precision grip (also present in 6-million-year-old Orrorin) and a non-prehensile hallux.

Curvas de crescimento de plantas de mandioca submetidas a doses de potássio

Potassium is considered nutrient extracted over cassava. Thus, its low availability in the soil affects plant growth, reflecting the expansion of cultivated area and productivity of crops potassium deficient. The objective of this present work was to establish growth curves of plants cassava cultivar Aciolina submitted to five doses of potassium, grown in Roraima savannah environment. The experimental design was in blocks at random in scheme of split plots, with four replications. Five doses of potassium (0, 30, 60, 120 and 240 kg ha-1 K2O) were randomized in the plots and evaluation times (150, 210, 270 and 360 days after planting - DAP) in the subplots. The variables evaluated: stem diameter, height of first ramification, plant height and leaf characteristics. The height growth of cv. Aciolina occurred at all levels of fertilization with potash, indicating that the low content of K restricts the growth of the plant height. The components of growth of the cassava plant, stem diameter, height of the first ramification and plant height are positively affected by increasing doses of potassium up to 240 kg ha-1. The width of the sheet, the number of lobes and the relationship between the length of the central lobe width of the central lobe are not affected by the potassium.

Earliest Evidence for the Ivory Trade in Southern Africa: Isotopic and ZooMS Analysis of Seventh–Tenth Century ad Ivory from KwaZulu-Natal

KwaGandaganda, Ndondondwane and Wosi were major Early Farming Community settlements in what is today the KwaZulu-Natal province of South Africa. These sites have yielded, among other remains, abundant evidence of ivory and ivory working dating to the seventh–tenth centuries ad, pre-dating by approximately 200 years the better-known ivory artefacts from sites in the Limpopo River Valley and surrounding regions. We report the results of carbon, nitrogen and strontium isotope analysis to explore the origins and procurement of this ivory, in combination with Zooarchaeology by Mass Spectrometry (ZooMS) to identify the species of animals from which it was derived. All of the ivory studied using ZooMS was elephant, despite the presence of hippopotamus remains on all three sites. Some ivory was probably obtained from elephant herds that lived close to the sites, in the densely wooded river valleys favoured by both elephants and early farmers. Other material came from savannah environments further afield. Ivory found at these three sites was drawn from different catchments, implying a degree of landscape/resource partitioning even at this early stage. These communities clearly invested substantial effort in obtaining ivory from across the region, which speaks to the importance of this commodity in the economy of the time. We suggest that some ivory items were for local use, but that some may have been intended for more distant markets via Indian Ocean trade.

Fossil Carder Bee's Nest from the Hominin Locality of Taung, South Africa.

The Buxton-Norlim Limeworks southwest of Taung, South Africa, is renowned for the discovery of the first Australopithecus africanus fossil, the ‘Taung Child’. The hominin was recovered from a distinctive pink calcrete that contains an abundance of invertebrate ichnofauna belonging to the Coprinisphaera ichnofacies. Here we describe the first fossil bee’s nest, attributed to the ichnogenus Celliforma, from the Plio-Pleistocene of Africa. Petrographic examination of a cell lining revealed the preservation of an intricate organic matrix lined with the calcitic casts of numerous plant trichomes–a nesting behaviour unique to the modern-day carder bees (Anthidiini). The presence of Celliforma considered alongside several other recorded ichnofossils can be indicative of a dry, savannah environment, in agreement with recent work on the palaeoenvironment of Plio-Pleistocene southern Africa. Moreover, the occurrence of ground-nesting bees provides further evidence that the pink calcrete deposits are of pedogenic origin, rather than speleogenic origin as has previously been assumed. This study demonstrates the potential value of insect trace fossils as palaeoenvironmental indicators.

Seasonal variations and population parameters explaining the use of space of neotropical rodents

Space use by animals has been studied for decades; however, gaps still exist in the understanding of how it is affected by biological and environmental factors. The aim of this study was to determine how biological traits, population parameters and seasonal variations affect the use of space by rodents in a tropical savannah environment. This study was performed in two grids in a grassland area at Aguas Emendadas Ecological Station between January 2004 and December 2013. The trapping sessions lasted six consecutive days and were performed monthly. Sherman traps, which were baited and reset daily, were used to capture the animals. The movement area was estimated using the minimum convex polygon method, and the mean movement distance was used to investigate the factors that affect the movement of the rodents. The hypothesis that a significant difference exists in the movement area size among species was corroborated; however, this difference was not related to body weight. As a general pattern for these rodents, males displayed larger movement areas than females. Movement area size showed an inverse relationship to population density. The understanding of the factors that affect the space use by rodents are complex and the interactions of these factors may also modulate space use by rodents. Our results suggest that space use is also affected by climatic variations.

Marine and terrestrial foods as a source of brain-selective nutrients for early modern humans in the southwestern Cape, South Africa

Many attempts have been made to define and reconstruct the most plausible ecological and dietary niche of the earliest members of the human species. While earlier models emphasise big-game hunting in terrestrial, largely savannah environments, more recent scenarios consider the role of marine and aquatic foods as a source of polyunsaturated fatty acids (PUFA) and other brain-selective nutrients. Along the coast of southern Africa, there appears to be an association between the emergence of anatomically modern humans and accumulation of some of the earliest shell middens during the Middle Stone Age (200–40 ka). Fragmentary fossil remains classified as those of anatomically modern humans, along with marine food residues and numerous material cultural indicators of increased social and behavioural complexity have been recovered from coastal sites.In this paper, new information on the nutrient content of marine and terrestrial foods available to early modern humans in the southwestern Cape is presented and compared with existing data on the nutritional value of some wild plant and animal foods in Africa. The results suggest that coastal foraging, particularly the collection of abundant and predictable marine molluscs, would have allowed early modern humans to exploit some of the richest and most accessible sources of protein, micronutrients and longer-chain omega-6 and omega-3 fatty acids. Reliable and accessible sources of omega-3 eicosapentaenoic and docosahexaenoic acid are considerably more restricted in terrestrial foods.

Composition of ambient and fresh biomass burning aerosols at a savannah site, South Africa

Atmospheric aerosols play a key role in climate change, and have adverse effects on human health. Given South Africa’s status as a rapidly-developing country with increasing urbanisation and industrial growth, information on the quality of ambient air is important. In this study, the chemical composition of ambient particles and the particles in fresh biomass burning plumes were studied at a savannah environment in Botsalano, South Africa. The results showed that Botsalano was regularly affected by air masses that had passed over several large point sources. Air masses that had passed over the coal-fired Matimba power station in the Waterberg, or over the platinum group metal smelters in the western Bushveld Igneous Complex, contained high sulfate concentrations in the submicron ranges. These concentrations were 14 to 37 times higher compared with air masses that had passed only over rural areas. Because of the limited nature of this type of data in literature for the interior regions of southern Africa, our report serves as a valuable reference for future studies. In addition, our biomass burning study showed that potassium in the fresh smoke of burning savannah grass was likely to take the form of KCl. Clear differences were found in the ratios for potassium and levoglucosan in the smouldering and flaming phases. Our findings highlight the need for more comprehensive chamber experiments on various fuel types used in southern Africa, to confirm the ratio of important biomass burning tracer species that can be used in source apportionment studies in the future.

Spatial and temporal patterns of home range use by olive baboons (Papio anubis) in eastern Laikipia, Kenya

AbstractThe study investigated the relationship between topography, seasonal food availability and home range use by a troop of olive baboons (Papio anubis) in a dry savannah environment. Valleys were the most utilized parts of the home range in dry seasons while old boma sites were more frequently used in the wet season. Herb‐layer food biomass decreased significantly in dry seasons. The flowers of both Acacia tortilis and Acacia etbaica were available only in dry seasons with valleys having the highest biomass. The biomass of Acacia nilotica seeds was higher in valleys than on other locations. Leaves of the shrub Lycium europaeum were available on all locations in the wet season but valleys had the highest biomass of this food type. Herb‐layer baboon food biomass at ridge tops, slopes, valleys and old boma sites showed similar trends in productivity between seasons. Baboons tracked food along the soil catenas by feeding at ridge tops and old boma sites where foods were available during the wet season and exploiting food sources at the valleys during the dry seasons. Food availability was related to the catena effect and baboons used the catenas in the home range in a predictable manner.

Marcusenius desertus sp. nov. (Teleostei: Mormyridae), a mormyrid fish from the Namib desert

We critically compared Marcusenius specimens from the mouth of the Cunene River on the Namibia/Angola border, a harsh desert environment on the Atlantic Ocean coast virtually devoid of aerial insects with aquatic larvae which are an important food item, with Marcusenius multisquamatus Kramer & Wink, 2013 from the escarpment region of that same river, in a relatively rich and productive subtropical savannah environment. River mouth specimens were differentiated in morphology and electric organ discharges, as determined by ANOVA/MANOVA comparisons, principal component and discriminant analyses on morphological and electrophysiological characters, and genetics, including sequences of the mitochondrial cytochrome b gene, indicating reproductive isolation. Specimens from the river mouth differed from M. multisquamatus, their closest relatives, by having a shorter snout, a smaller eye diameter, and smaller nares separation. River mouth specimens were also differentiated from other, increasingly less-close relatives, such as M. altisambesi Kramer et al., 2007 from the Okavango River, Botswana, and from M. krameri Maake et al., 2014 from the Limpopo System, South Africa. We therefore designate the new species Marcusenius desertus sp. nov. for the Cunene River mouth population.

Harvesting period of Murici (Byrsonima crassifolia Kunth) fruit in relation to physical and chemical parameters evaluated during fruit development

The fruits were harvested for six consecutive years during the rainy season from a population native to a savannah environment, and they were analyzed at intervals of seven days after anthesis (DAA). Chemical analyses were conducted (pH, total acidity, soluble solids, total and reducing sugars, total and soluble pectin, polygalacturonase enzyme (PG) and pectin methyl esterase (PE) enzymes, phenolic compounds, vitamin C and antioxidant activity by the oxygen radical absorbance capacity (ORAC) and α, α-diphenyl-β-picrylhydrazyl (DPPH) methods), respiratory activity was determined, and physical evaluations were performed (diameter and fruit and pulp fresh weight). The experiment was conducted in a completely randomized design (CRD) with a regression analysis and model fitting using the statistical F-test at a 5% significance level. The results showed climacteric behavior of the fruit as well as significant antioxidant activity related to the presence of phenolic compounds and vitamin C. The harvesting time, according to the evaluated parameters, was determined to be the interval between 28 and 35DAA.