Estado de conservação e distribuição potencial de uma espécie de planta endêmica “Warneckea sessilicarpa” em Moçambique

Abstract

In Mozambique, it is estimated that approximately 50% of endemic species have been assessed using the International Union for Conservation of Nature (IUCN) Red List criteria. Some are threatened, with the factors behind possible extinction being: habitat loss and degradation driven by high human population growth and the consequent increase in demand for land that puts increasing pressure on natural habitats. The objectives of the study are: to assess the extinction risk of Warneckea sessilicarpa using IUCN criteria and to build potential distribution models of the species (MaxEnt) from new occurrence data together with environmental variables. The species was previously classified as Critically Endangered (CR) using criterion B - CR B1ab (iii,v) with EOO and AOO estimated at 20 km2 and 7,306 km2. The existence of new occurrence data justified its (re)evaluation, using the geographic coverage criterion established by the IUCN and the results generated by species distribution models (ArcGis version 10.8 and MaxEnt Software, which only requires presence data). The extent of occurrence (EOO) was estimated by applying the Minimum Convex Polygon (MCP) method and the standard 2 km x 2 km grid method to determine the area of ​​occupancy (AOO). With the new occurrence data, the species changed its classification to Endangered (EN) with EOO and AOO estimated at 8,884.9 km2 and 52,676 km2, respectively. These results, added to the models generated by MaxEnt, accurately produced the current suitable habitat area for the species. The performance of the Warneckea sessilicarpa distribution model was satisfactory, with an area under the curve (AUC) value of 0.983, with an estimated potential niche of 1,371.52 km2. Considering the set of 14 environmental variables, the jackknife test indicated that precipitation in the driest quarter (Bio_17) was the environmental variable of greatest relative importance for modeling the species distribution, with an individual contribution of 30.9%. The study confirmed that the quality and quantity of data constitute an effective approach in accurately assessing the threat category of this species under the IUCN Red List criteria and that the models developed constitute an essential tool for understanding the relative suitability of the habitat occupied by the species and the potential distribution of the species in the coastal region of the provinces of Zambézia and Nampula. These results added to the models generated by MaxEnt accurately produced the current suitable habitat area for the species, the performance of the distribution model for Warneckea sessilicarpa was satisfactory, with an area under the curve (AUC) value of 0.983, with an estimated potential niche of 1,371.52 km2. Considering the set of 14 environmental variables, the jackknife test indicated that the rainfall of the driest quarter (Bio_17) was the environmental variable of greatest relative importance for modelling the species' distribution, with an individual contribution of 30.9 %. The study confirmed that the quality and quality and quantity of data is an effective approach to accurately assessing the category of threat of this species under the IUCN Red List criteria and that the models developed are an essential tool for understanding the relative suitability of the the relative suitability of the habitat occupied by the species and the species' potential distribution in the coastal region provinces of Zambézia and Nampula.(TRADUÇÃO NOSSA)