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The novel coronavirus (COVID-19) pandemic is causing devastating demographic, social, and economic damage globally. Understanding current patterns of the pandemic spread and forecasting its long-term trajectory is essential in guiding policies aimed at curtailing the pandemic. This is particularly important in regions with weak economies and fragile health care systems such as West Africa. We formulate and use a deterministic compartmental model to (i) assess the current patterns of COVID-19 spread in West Africa, (ii) evaluate the impact of currently implemented control measures, and (iii) predict the future course of the pandemic with and without currently implemented and additional control measures in West Africa. An analytical expression for the threshold level of control measures (involving a reduction in the effective contact rate) required to curtail the pandemic is computed. Considering currently applied health control measures, numerical simulations of the model using baseline parameter values estimated from West African COVID-19 data project a 67% reduction in the daily number of cases when the epidemic attains its peak. More reduction in the number of cases will be achieved if additional public health control measures that result in a reduction in the effective contact rate are implemented. We found out that disease elimination is difficult when more asymptomatic individuals contribute in transmission or are not identified and isolated in a timely manner. However, maintaining a baseline level of asymptomatic isolation and a low transmission rate will lead to a significant reduction in the number of daily cases when the pandemic peaks. For example, at the baseline level of asymptomatic isolation, at least a 46% reduction in the transmission rate is required for disease elimination. Additionally, disease elimination is possible if asymptomatic individuals are identified and isolated within 5 days (after the incubation period). Combining two or more measures is better for disease control, e.g., if asymptomatic cases are contact traced or identified and isolated in less than 8 days, only about 29% reduction in the disease transmission rate is required for disease elimination. Furthermore, we showed that the currently implemented measures triggered a 33% reduction in the time-dependent effective reproduction number between February 28 and June 26, 2020. We conclude that curtailing the COVID-19 pandemic burden significantly in West Africa requires more control measures than those that have already been implemented, as well as more mass testing and contact tracing in order to identify and isolate asymptomatic individuals early.

It is prominently claimed that enhancing forest diversity would play a dual role of nature conservation and climate regulation. While the idea is intuitively appealing, studies show that species richness effects on above‐ground carbon (AGC) are not always positive, but instead unpredictable especially across scales and complex terrestrial systems having large‐diameter and tall‐stature trees. Previous studies have further considered structural complexity and larger trees as determinants of AGC. Yet it remains unclear what drives differential diversity–AGC relationships across vegetation types. Here we test whether structural complexity and large‐sized trees play an influential role in explaining shifting diversity–AGC relationships across vegetation types, using a 22.3‐ha sampled dataset of 124 inventory plots in woodlands, gallery forests, tree/shrub savannas and mixed plantations in West Africa. Natural vegetation had greater species richness and structural complexity than mixed plantations, as expected. In addition, AGC was highest in gallery forests and mixed plantations, which is consistent with favourable environmental conditions in the former and high stocking densities and presence of fast‐growing species in the latter. Significant interaction effects of species richness and vegetation on AGC revealed a vegetation‐dependent species richness–AGC relationship: consistently, we found positive species richness–AGC relationship in both mixed plantations and woodlands, and nonsignificant patterns in gallery forests and tree/shrub savanna. Furthermore, there was a vegetation‐dependent mediation of structural complexity in linking species richness to AGC, with stronger positive structural complexity effects where species richness–AGC relationships were positive, and stronger positive large‐sized trees’ effect where species richness–AGC relationships were neutral. Our study provides strong evidence of vegetation‐dependent species richness–AGC relationships, which operated through differential mediation by structural complexity of the species richness and large trees’ effects. We conclude that even higher species richness in diversified ecosystems may not always relate positively with AGC, and that neutral pattern may arise possibly as a result of larger dominant individual trees imposing a slow stand dynamic flux and overruling species richness effects. A free Plain Language Summary can be found within the Supporting Information of this article.

BackgroundTraditional knowledge about the use of medicinal plants for herbal drinks (HDs) is not well documented in the Azad Kashmir region despite their widespread use. This study highlights the taxonomic diversity and traditional knowledge on medicinal plants used for HDs while examining the diversity of diseases treated with HDs in the study area.MethodsIndividual discussions were conducted with 255 informants (84 women and 171 men). Data gathered included (i) informant age and gender, (ii) HD species and respective plant parts used, (iii) health disorders treated, and (iv) mode of preparation and utilizations. Quantitative ethnobotanical indices including relative frequency of citation (RFC), informant consensus factor (ICF), and use value (UV) were used for data analyses.ResultsAltogether, 73 medicinal plants belonging to 40 families and 66 genera were reported to be used in HD preparations, with Asteraceae being the richest family. The average number of HD species cited was 9.09 ± 0.17 per informant and did not vary either by age or gender. In addition, men and women, and adults and the young used the same pool of species (dissimilarity nearly zero). The most used plant parts were leaves (20.00%), roots (17.25%), and fruits (16.47%). Based on UV, the top five most used species were Valeriana jatamansi, Isodon rugosus, Onopordum acanthium, Acacia nilotica, and Viola canescens; and the UV was similar among gender and age categories too. The most utilized herbal preparation forms included decoctions, infusions, and tea. One hundred and eleven diseases grouped into 13 ailment categories were reported to be cured using HDs. The main category of disease treated with HDs was gastrointestinal (GIT) disorders (RFC = 17.43%). Relatively few species were used by a large proportion of informants for each category of ailment (ICF ≥ 0.60). Only one species was used for “glandular disorders” and “eye diseases” (ICF = 1).A novelty of about 22% (16 species) was recorded for HD species in the present work.ConclusionThe diversity of medicinal plant species used as HDs and the associated traditional knowledge are of considerable value to the indigenous communities of the Azad Kashmir region. Therefore, there is a need for conservation and preservation of medicinal HD species as well as the wealth of indigenous knowledge. The conservation effort should be high for species in the ailments categories glandular disorders and eye diseases. The therapeutic uses of HDs have provided basic data for further research focused on phytochemical and pharmacological studies and conservation of the most important species.