Optimising mopane worm (Gonimbrasia belina) processing for improved nutritional and microbial quality.

Mopane worms (Gonimbrasia belina) is an important source of food and contribute to the nutrition of people who consume them. However, the traditional processing methods may have detrimental effects on the nutritional value and should also guarantee microbial quality. In this study, the nutritional composition and microbial quality of mopane worms processed under different boiling time (0-20 min) and drying temperature (40-60 °C) conditions were investigated and optimised using response surface methodology. An increase in the boiling time at the lowest drying temperature resulted in an increase in protein content and reduction in coliform counts. The optimum conditions of boiling for 20 min and drying at 40 °C resulted in mopane worms with a protein content of 49.4% DW and coliform counts <1.5 log cfu/g. In addition, high concentrations of crude fibre (13.6% DW) and fat (20.2% DW), as well as Fe (19.0 mg/100 g) and Zn (17.9 mg/100 g) were also recorded. A decrease in the total bacterial count, Escherichia coli and yeasts and moulds at the boiling time ≥20 min irrespective of the drying temperature suggested that exposure to heat reduced the microbial growth and contamination. Reduction of the mopane worms' moisture content (<7%) due to drying further slowed down the rate of microbial growth. The optimal processing conditions (boiling for 20 min and drying at 40 °C) are recommended for pretreatment of mopane worms prior to further processing into various products.

The Use of Gonimbrasia belina (Westwood, 1849) and Cirina forda (Westwood, 1849) Caterpillars (Lepidoptera: Sarturniidae) as Food Sources and Income Generators in Africa.

Gonimbrasia belina (mopane worm) and Cirina forda caterpillars (Lepidoptera: Saturniidae) are mostly found in shrubs and trees, from where they are collected as larvae and are widely consumed across southern Africa by rural and increasingly urban populations. These caterpillars are among the most prominent, traded, and economically beneficial edible insects found in Western African countries, but also in South Africa, Zimbabwe, Botswana, and the Democratic Republic of the Congo. Over the years, these caterpillars have evolved from being part of the diet in various communities to playing a vital role in income generation. In addition, consumption of G. belina and C. forda caterpillars as potential food sources has gained momentum due to their potential for contributing to livelihoods and mitigating food security challenges across Africa while providing significant benefits to developing countries on a socio-economic and ecological level. Edible caterpillars serve as a good source of rich nutrients such as proteins, fatty acids, and micronutrients and can be used in formulating nutrient-dense complementary foods. However, limited information is available, specifically on different trees that serve as hosts to these caterpillars, as they depend on the leaves as their only source of food. In addition, the review aims to critique and document knowledge on the nutritional benefits, acceptance of the use of these caterpillars as food security, commercial value, and level of acceptance towards the utilization of caterpillars as food sources.

Enhanced establishment of Colophospermum mopane (Kirk ex Benth.) seedlings for phytoremediation of Cu-Ni mine tailings.

This study was carried out to determine the effect of cow manure amendment and the method of planting on the growth, survival, and heavy metal accumulation of Colophospermum mopane seedling grown on Bamangwato Concessions Limited (BCL) mine tailings. Different planting strategies were employed where the mopane seedlings were planted with bare roots (devoid of potting soil) and without cow manure (T1, - CM - Soil); with the potting soil adhering to the roots but without cow manure (T2, - CM + Soil); with bare roots in the presence of cow manure (T3, + CM - Soil); and with potting soil intact together with cow manure (T4, + CM + Soil). Cow manure increased the pH of the mine tailings enhancing the survival and growth of the mopane seedlings. Seedlings grown under T1 conditions had a higher concentration of the heavy metals As, Cr, Cu, Mn, Ni, Pb, Zn, Sb, and Sr in their shoots compared to those grown under a T4 environment consisting of potting soil with cow manure. Cow manure decreased the availability of these heavy metals in mine tailings through the humic substance which adsorbed the heavy metal while the soil adhering to the roots diluted the concentration of heavy metals in the rhizosphere thus reducing the uptake and toxicity. Overall, the establishment of mopane seedlings in mine tailings could be enhanced by cow manure amendments and with soil adhering to its roots during transplanting.

Sensitisation to Imbrasia belina (mopane worm) and other local allergens in rural Gwanda district of Zimbabwe.

BACKGROUND: The prevalence of allergic diseases is increasing in Zimbabwe and the data relate to local as well as exotic allergen sources. As entomophagy, the practice of eating insects, is a recognised source of local allergens, we sought to measure the prevalence of and risk factors for sensitisation to Imbrasia belina (mopane worm), a popular edible insect. This was investigated alongside other locally relevant allergens in a rural community in Gwanda district, south of Zimbabwe. METHODS: A cross sectional study was conducted among 496 adults and children aged 10 years and above in Gwanda district, a mopane worm harvesting area in Zimbabwe. Data on individual characteristics and mopane worm exposure factors were collected using questionnaires. Sensitivity to allergens was assessed by performing skin prick tests at a local clinic using 10 different commercial allergen extracts (Stallergenes, France) and in-house extracts of mopane worm (Imbrasia belina) and mopane leaves (Colophospermum mopane). Data were analysed using Stata version 13 software. RESULTS: The prevalence of sensitisation to at least one allergen was 31.17% (n = 144). The prevalence of atopy was higher in adults (33.33%) than in children (23.53%) (p = 0.059). The commonest inhalant allergen sources were mopane worm (14.29%), Tyrophagus putrescentiae (14.29%), mopane leaves (13.42%), Alternaria alternata (6.49%) and Dermatophagoides pteronyssinus (6.49%). Polysensitisation was demonstrated in the study population and of the 108 participants (75%) who were sensitised to two or more allergens, 66 (61%) were women. Sensitisation to mopane worm and mopane leaves often clustered with Tyrophagus putrescentiae amongst adults. Adjusted logistic regression analyses between mopane worm sensitisation and self-reported exposure variables showed that sensitisation was more likely amongst mopane worm harvesters (OR = 1.92, 95%CI = 0.77-4.79), those who cooked or roasted mopane worms during harvesting (OR = 2.69, 95%CI = 0.78-9.31) and harvesting without personal protective equipment (PPE) (OR = 2.12, 95%CI = 0.83-5.44) compared to non-harvesters. CONCLUSION: Atopic sensitization was common in this mopane worm harvesting community in Gwanda district of Zimbabwe. There was frequent co-sensitisation of mopane worm and mopane leaves with Tyrophagus putrescentiae in children and adults. It is important to determine the clinical relevance of our findings, particularly relating to mopane worm sensitisation.

Determination of furanic compounds in Mopane worms, corn, and peanuts using headspace solid-phase microextraction with gas chromatography-flame ionisation detector.

A headspace-solid phase microextraction - gas chromatography-flame ionisation detector (HS-SPME-GC/FID) method was developed for the simultaneous determination of furan, 2-methylfuran and 2-furaldehyde in thermally processed Mopane worms, corn, and peanuts. The optimal HS-SPME conditions with polydimethylsiloxane/carboxen/divinylbenzene (PDMS/CAR/DVB) fiber were 30 °C, 40 min and 600 rpm stirring speed. The recoveries, detection and quantification limits for the analytes in food samples were 67-106%, 0.54-3.5 µg kg-1, and 1.8-12 µg kg-1, respectively. These results showed that the developed method was accurate, reproducible, and sensitive for the determination of furan, 2-methylfuran and 2-furaldehyde in complex food matrices with limited interference from other components. The optimised analytical method was applied for monitoring the presence of the furanic compounds in heat-processed South African foods. Although 2-furaldehyde was not detected in food samples, the maximum concentrations of 24 and 95 µg kg-1 were found for furan and 2-methylfuran, respectively.

Insects' Production, Consumption, Policy, and Sustainability: What Have We Learned from the Indigenous Knowledge Systems?

Edible insects can be produced sustainably, with less environmental impact than other forms of livestock. Globally, over 2000 edible insect species have been reported and are regarded as a great source of nutrition, both as food and feed. Over the years, rural people have used indigenous knowledge to either store or process such insects. However, such valuable knowledge, if not properly recorded and documented, can easily be lost. Thus, there is a need to strike a balance between the use of indigenous and scientific knowledge to produce and process these delicacies. In addition, such indigenous knowledge is vital for preserving biodiversity, since insects are good indicators of climate change as it influences their development, reproduction, and survival. Therefore, successful and sustainable solutions may lie in bringing back indigenous knowledge systems.

What shapes the range edge of a dominant African savanna tree, Colophospermum mopane? A demographic approach.

Climate is widely assumed to be the primary process that limits the distribution ranges of plants. Yet, savannas have vegetation not at equilibrium with climate, instead its structure and function are shaped by interactions between fire, herbivory, climate, and vegetation. I use the rich literature of a dominant African savanna woody plant, Colophospermum mopane, to demonstrate that climate and disturbance interact with each demographic stage to shape this species range limits. This synthesis highlights that climate-based predictions for the range of C. mopane inadequately represents the processes that shape its distribution. Instead, seed bank depletion and rainfall limitation create a demographic bottleneck at the early seedling stage. The legacy of top-kill from disturbance changes tree stand architecture causing a critical limitation in seed supply. Exposure to top-kill at all demographic stages causes a vigorous resprouting response and shifts tree architecture from that of 1-2 stemmed tall trees to that of a short multi-stemmed shrub. The shorter, multi-stemmed shrubs are below the height threshold (4 m) at which they can produce seeds, resulting in shrub-dominated landscapes that are effectively sterile. This effect is likely most pronounced at the range edge where top-kill-inducing disturbances increase in frequency. The proposed mechanistic, demographic-based understanding of C. mopane's range limits highlights the complexity of processes that interact to shape its range edges. This insight serves as a conceptual model for understanding the determinants of range limits of other dominant woody savannas species living in disturbance limited ecosystems.

A feasibility study to assess Imbrasia belina (mopane worm) sensitisation and related respiratory health outcomes in a rural community in Gwanda district, Zimbabwe.

BACKGROUND: Allergic diseases are considered to be some of the fastest growing chronic conditions in Africa. Of concern is the paucity of knowledge about the local environment and its role in allergic disease development. In response to this, we explored whether Imbrasia belina, a popular indigenous edible insect commonly known as mopane worm, is a potential allergen of clinical and public health significance in Zimbabwe. This study was intended to assess the plausibility and feasibility of this hypothesis with a view to evaluate the insect's health impact in a larger study. METHODS: The study participants included male and female villagers aged 10 years and above in Gwanda district, Zimbabwe. Eligible participants who completed the household questionnaire were referred to the local clinic for skin prick tests and to measure lung function and allergic airway inflammation. Allergen sensitisation patterns were evaluated using 10 different inhalant allergen extracts including an in-house preparation of mopane worm. Lung function was measured with a Koko Legend spirometer, and fractional exhaled nitric oxide levels (FeNO) (NIOX VERO) were measured in participants with at least one abnormal spirometric parameter. Data was analysed using Stata version 13 software. RESULTS: Of the 46 eligible participants that completed the household questionnaire, 17 went to the clinic giving a response rate of 37%. The majority who completed the questionnaire were adults (91%) and the children (9%) were all female. The prevalence of sensitisation to Imbrasia belina was 50%, and the prevalence ranged from 22 to 72% for the other allergens including cockroach, mosquito and house dust mites. The data collection tools were safe and well tolerated by participants with no adverse events reported. Self-reported respiratory symptoms, abnormal lung function and elevated FeNO were recorded amongst participants sensitised to mopane worm. CONCLUSION: Pre-defined feasibility criteria were met with the exception of a lower than expected response rate for clinic data collection in this pilot study. For the main study, modifying the sampling strategy and applying more consistent community engagement will improve the response rates.

Mining the Microbiome of Key Species from African Savanna Woodlands: Potential for Soil Health Improvement and Plant Growth Promotion.

(1) Aims: Assessing bacterial diversity and plant-growth-promoting functions in the rhizosphere of the native African trees Colophospermum mopane and Combretum apiculatum in three landscapes of the Limpopo National Park (Mozambique), subjected to two fire regimes. (2) Methods: Bacterial communities were identified through Illumina Miseq sequencing of the 16S rRNA gene amplicons, followed by culture dependent methods to isolate plant growth-promoting bacteria (PGPB). Plant growth-promoting traits of the cultivable bacterial fraction were further analyzed. To screen for the presence of nitrogen-fixing bacteria, the promiscuous tropical legume Vigna unguiculata was used as a trap host. The taxonomy of all purified isolates was genetically verified by 16S rRNA gene Sanger sequencing. (3) Results: Bacterial community results indicated that fire did not drive major changes in bacterial abundance. However, culture-dependent methods allowed the differentiation of bacterial communities between the sampled sites, which were particularly enriched in Proteobacteria with a wide range of plant-beneficial traits, such as plant protection, plant nutrition, and plant growth. Bradyrhizobium was the most frequent symbiotic bacteria trapped in cowpea nodules coexisting with other endophytic bacteria. (4) Conclusion: Although the global analysis did not show significant differences between landscapes or sites with different fire regimes, probably due to the fast recovery of bacterial communities, the isolation of PGPB suggests that the rhizosphere bacteria are driven by the plant species, soil type, and fire regime, and are potentially associated with a wide range of agricultural, environmental, and industrial applications. Thus, the rhizosphere of African savannah ecosystems seems to be an untapped source of bacterial species and strains that should be further exploited for bio-based solutions.

Novel species of Huntiella from naturally-occurring forest trees in Greece and South Africa.

Huntiella species are wood-infecting, filamentous ascomycetes that occur in fresh wounds on a wide variety of tree species. These fungi are mainly known as saprobes although some have been associated with disease symptoms. Six fungal isolates with typical culture characteristics of Huntiella spp. were collected from wounds on native forest trees in Greece and South Africa. The aim of this study was to identify these isolates, using morphological characters and multigene phylogenies of the rRNA internal transcribed spacer (ITS) region, portions of the ß-tubulin (BT1) and translation elongation factor 1α (TEF-1α) genes. The mating strategies of these fungi were also determined through PCR amplification of mating type genes. The study revealed two new species; one from Platanus orientalis in Greece and one from Colophospermum mopane and Senegalia nigrescens in South Africa. These novel taxa have been provided with the names, H. hellenica sp. nov. and H. krugeri sp. nov., respectively. The former species was found to have a homothallic and the latter a heterothallic mating system.

Morphometric data of Colophospermum mopane leaves in the Limpopo Province of South Africa.

Colophospermum mopane (J. Kirk ex Benth.) J. Kirk ex J. Léonard occurs over a very large region of southern Africa, occupying varying habitats that could account for ecotypic speciation. This investigation statistical analysed the variations in the architecture of the leaflets of C. mopane from the Limpopo Province of South Africa, with the purpose of ascertaining whether natural variability can act as a source of information for investigating ecotypic variation. Leaf morphometric traits, such as leaflet area, length, width, perimeter, pulvinus angle and the acuteness of the apex, were digitally measured and statistically compared for intra- and inter-population variability. Data indicate that the intra-population variation is 35.33% (statistical similarity: 64.67%), while the inter-population (n = 5) variation is 46.67% (statistical similarity: 53.33%).

Data on mopane worm (Imbrasia belina) microorganisms from Limpopo Province, South Africa.

Mopane worm samples, obtained from different districts of the Limpopo Province of South Africa between April and July 2018, were investigated for the incidence of microbial flora. Over a period of ten weeks, samples consisting of market-obtained, field-prepared and sun- dried worms, were evaluated. It was revealed that after cooking at 89- 93°C, the microbial population was reduced to less than 9 000 CFU/g. The most prominent microbial populations cultured after cooking were spore- formers. Field-processed worms had a microbial population of 4 × 104 -1 × 108 CFU/g. Bacteria and fungi isolated included Aspergillus niger, Enterobacter aglomerans, Escherichia coli, Micrococcus luteus and Penicillium sp. Total microbial population ranged between 4 × 105 and 3 × 105 CFU/g after cooking. Total bacterial count increased in the sun- dried worms from 3 × 105-4 × 105 CFU/g, while it decreased from 2.0 × 105-1.4 × 105 CFU/g after cooking. This data can be used to generate safety guidelines related to the processing of edible insects, such as mopane worms.

Data on dendrometric parameters, basic wood density, below- and aboveground biomass of tree species from Mangrove, Miombo, Mopane, and Mecrusse woodlands.

Mozambique is composed by the following forest types: Miombo, Mopane, Mecrusse, and Mangrove. Data on basic wood density at different height levels, tree component dry-mass, and other dendrometric parameters (root collar diameter, diameter at breast height, crown height, crown diameter, live crown length, and stem volume) for eight species typical of Miombo (Afzelia quanzensis Welw., Millettia stuhlmannii Taub., Pterocarpus angolensis DC., Brachystegia spiciformis Benth., and Julbernardia globiflora (Benth.) Troupin), Mopane (Colophospermum mopane Kirk ex J. Léonard), Mecrusse (Androstachys johnsonii Prain), and Mangrove (Avicennia marina (Forssk.)) forests collected from five provinces (Maputo, Gaza, Inhambane, Sofala, and Manica) of Mozambique are presented in this article. Biomass data of Miombo, Mecrusse, and Mopane woodlands were collected destructively, whereas those of Mangrove forests were collected using non-destructive methods.

Mitochondrial genomes and polymorphic regions of Gonimbrasia belina and Gynanisa maja (Lepidoptera: Saturniidae), two important edible caterpillars of Southern Africa.

Mopane worms are the vernacular designation for the edible caterpillars of the African emperor moths Gonimbrasia belina and Gynanisa maja. Both species, particularly G. belina, are widely harvested in Southern Africa, and their populations are declining. Despite their commercial, nutritional, and cultural importance, their genetic data are currently unavailable. We sequenced two complete mitogenomes from each species using Ion Torrent technology, and identified informative markers in the complete mitogenomes of the two species for use in future studies. Comparing the conspecific mitogenomes allowed the identification of regions with high nucleotide diversity in ATP6, ND1, ND4, ND5, ND6, and CYTB genes. The final panels of markers will allow for the survey of 3117 bp in G. belina, and 3990 bp in Gy. maja. Phylogenetic reconstruction within the family Saturniidae recovered the tribe Bunaeini as monophyletic and basal to Saturniidae, and the tribe Attacini as a monophyletic clade nested within the tribe Saturniini. The G. belina and Gy. maja mitogenomes are the first representatives of African Saturniidae, a taxonomic group with relevance as a food resource on the continent. This study represents the first step towards assessing the genetic diversity, population structure, and phylogeography of African edible caterpillars.

Indigenous Knowledge about Consumption of Edible Insects in South Africa.

Consumption of edible insects is an indigenous practice that has played an essential role in human nutrition across Africa. The traditional use of insects forms an important part of food culture in Africa, and insects are consumed either as a delicacy, emergency, or staple source of food. However, indigenous knowledge about insect consumption is being lost because recent generations have adopted western methods and paid less attention to traditional practices. We conducted 500 questionnaires in five local municipalities in Kwazulu-Natal (KZN), and 122 questionnaires in four local municipalities in Vhembe district in Limpopo, South Africa, to document indigenous knowledge about edible insects' consumption, collection, and preparation methods used in Limpopo and KZN. Eight insect species belonging to five insect orders were used as food in Limpopo and KZN, with mopane worms (94%) and termites (70%) being the most preferred species by respondents in Limpopo and KZN, respectively. Ninety-five percent of the respondents occasionally consumed insects in Limpopo, while only 28% did so in KZN. Nutritional benefits and tradition were the main reasons for consuming insects. Edible insects are a nutritious diet and play an important role in people's livelihoods in rural areas. However, there was a notable decline in entomophagy, particularly in KZN. The decline may be related to occidental acculturation, discomfort associated with eating insects, and declining insect availability. To promote entomophagy, the authorities should encourage people to include edible insects in their diets because of their nutritional value. In addition, edible insect flour should be incorporated in food products such as biscuits, bread, energy bars, cereal, and cookies to promote acceptability.

Ecohydrological threats to Colophospermum mopane in southern Zimbabwe.

Rapid ecohydrological changes in semi-arid landscapes are increasingly threatening humanity's life-support systems and eroding many of the ecosystem services (ESs) upon which humans occupying such regions depend. Knowing which services and ecohydrological changes to be most concerned about is indispensable to maintaining the general health of such ecosystems and for developing effective ecosystem management practices. In the semi-arid regions of southwestern Zimbabwe where a large population of rural households depend on ESs extracted from the Colophospermum mopane tree, such understanding may be critical in reversing potential ES losses that may have catastrophic effects on the lives of many. We surveyed a total of 127 rural households who occupy the semi-arid landscapes of the Colophospermum mopane belt in southern Zimbabwe. We assessed the ecohydrological conditions characterising ecosystems where they obtain ES provisioning goods using a number of ecohydrological variables commonly cited in the literature on ecohydrology. Building on principal component analysis (PCA), we employed a hierarchical agglomerative clustering method to create unique clusters of households that depicted different levels of risks or threats associated with their ES provisioning harvesting practices. Multiple regression analysis was further performed to identify significant ecohydrological cluster-defining variables. Our results showed that spatial differences in ecohydrological parameters resulted in four distinct ES resource thresholds depicting four categories of risks that households face in extracting such resources in nearby landscapes. We concluded by proposing a number of landscape restoration or management practices targeted at reversing potential ES losses and subsequently safeguarding the livelihoods of many who depend on ESs.

Diversification of African Tree Legumes in Miombo-Mopane Woodlands.

The southern African Miombo and Mopane ecoregions constitute a unique repository of plant diversity whose diversification and evolutionary history is still understudied. In this work, we assessed the diversity, distribution, and conservation status of Miombo and Mopane tree legumes within the Zambezian phytoregion. Data were retrieved from several plant and gene databases and phylogenetic analyses were performed based on genetic barcodes. Seventy-eight species (74 from Miombo and 23 from Mopane, 19 common to both ecoregions) have been scored. Species diversity was high within both ecoregions, but information about the actual conservation status is scarce and available only for ca. 15% of the species. Results of phylogenetic analyses were consistent with current legume classification but did not allow us to draw any conclusion regarding the evolutionary history of Miombo and Mopane tree legumes. Future studies are proposed to dissect the diversity and structure of key species in order to consolidate the network of conservation areas.

Enzyme activity and histological analysis of Clarias gariepinus fed on Imbrasia belina meal used for partial replacement of fishmeal.

An experiment was carried out to assess the effect of replacing fishmeal with mopane worm meal in the diet of Clarias gariepinus. Juvenile C. gariepinus weighing 67.04 ± 3 g were stocked in 15 rectangular concrete tanks connected to a recirculating system. Five diets denoted D1, D2, D3, D4 and D5 were formulated to replace fishmeal with mopane worm meal at 0, 10, 20, 40 and 60%. Triplicate groups of C. gariepinus were randomly assigned to each diet at a stocking density of 100 fish per tank. The fish were fed to apparent satiation twice daily for 51 days. All growth performance indices declined with higher mopane worm inclusion levels. Specific growth rate (SGR) declined from 1.85%/day in the control diet to 1.43%/day in diet 5. Protein efficiency ratio (PER) also declined from 25.27% in the control diet to 19.30% in diet 5. Apparent digestibility coefficient (ADC) followed a similar pattern declining from 92.2% in the control diet to 87.1% in diet 5. Both amylase and protease activity in the stomach increased with higher mopane worm inclusion levels. Despite the increased enzyme activity in the stomach, SGR declined. The decline in SGR was attributed to high acid detergent fibre (ADF 58.4 g/kg) and chitin in the mopane worm diets. Lipase and chitinase did not show any discernible pattern with high mopane worm inclusion levels in the stomach. In the intestines, protease, lipase and chitinase did not show any discernible pattern with high mopane worm inclusion levels. Consequently, the relationship between SGR and all these enzymes was weak. However, amylase activity declined with higher mopane worm inclusion levels in the intestines, and this resulted in decreased SGR (r2 = 0.6722). The negative effects of mopane worm meal were further confirmed by the increase in liver degradation scores at high mopane worm inclusion levels. The liver degradation score increased from 1.12 in the control to 2.46 in diet 5.

Least squares-based biomass conversion and expansion factors best estimate biomass than ratio-based ones: Statistical evidences based on tropical timber species.

Due to its readiness to convert stem volumes (V) into biomass, national and regional aboveground biomass estimates and greenhouse gas reporting are generally based on biomass conversion and expansion factors (BCEFs). BCEF-based biomass (W) is computed by the following regression through the origin (RTO): W = BCEF × V. However, the regression slope (BCEF) is not obtained using least squares (LS); it is obtained as the ratio of observed biomass and stem volume. Therefore, the sum of squares of the residuals is not minimum. This may lead to strongly biased biomass estimates. Furthermore, in this case, the biomass is not modelled. In the present study, it was suggested that BCEFs should be obtained using LS through RTO. The objective of this study was to compare LS-based and ratio-based BCEFs with regard to predictive accuracy and ability. A dataset of 75 trees from 4 species was used for the comparisons. •LS-based BCEFs were associated with higher predictive accuracy and ability than ratio-based ones.•It was proved that RTO is appropriated for estimating BCEFs, as the intercept α was consistently not significant.•Ratio-based BCEFs may lead to seriously biased biomass and carbon stocks estimates.•BCEFs should be estimated using least squares.

Pre-rain green-up is ubiquitous across southern tropical Africa: implications for temporal niche separation and model representation.

Tree phenology mediates land-atmosphere mass and energy exchange and is a determinant of ecosystem structure and function. In the dry tropics, including African savannas, many trees grow new leaves during the dry season - weeks or months before the rains typically start. This syndrome of pre-rain green-up has long been recognized at small scales, but the high spatial and interspecific variability in leaf phenology has precluded regional generalizations. We used remote sensing data to show that this precocious phenology is ubiquitous across the woodlands and savannas of southern tropical Africa. In 70% of the study area, green-up preceded rain onset by > 20 d (42% > 40 d). All the main vegetation formations exhibited pre-rain green-up, by as much as 53 ± 18 d (in the wet miombo). Green-up showed low interannual variability (SD between years = 11 d), and high spatial variability (> 100 d). These results are consistent with a high degree of local phenological adaptation, and an insolation trigger of green-up. Tree-tree competition and niche separation may explain the ubiquity of this precocious phenology. The ubiquity of pre-rain green-up described here challenges existing model representations and suggests resistance (but not necessarily resilience) to the delay in rain onset predicted under climate change.