Vegetation cover, simulated microclimate, and simulated thermal safety margin in a biosphere reserve and its surroundings in 1999 and 2020
Description
To determine whether in general protected areas (PAs) provide protection from overheating for the lizard populations inhabiting them, we compared the effect of a PA on vegetation cover, and in turn on the microclimate experienced by lizards, at their spatial scale and considering their thermoregulatory behaviors. Using a mechanistic niche model (NicheMapR), we tested whether the Sierra de Huautla Biosphere Reserve (REBIOSH) had higher vegetation cover, cooler microclimates, and higher thermal safety margins (TSM) for simulated Sceloporus horridus lizards compared to adjacent unprotected areas to the north (NAA) and south (SAA) in 1999—when the reserve was declared—and 2020. The study area is in south-central Mexico and the considered surface is mainly occupied by the seasonally dry tropical forest. Within each polygon, we randomly placed 150 sampling points to which we assign data of our study variables. The sampling points have a spatial resolution of 30 m. We characterized the vegetation cover using the normalized difference vegetation index (NDVI) * 100, that is to say, converted to a percentage. The microclimate was simulated at 3 or 200 cm perch height because the latter may be cooler than the former and S. horridus moves along such interval. We calculated the TSM as the voluntary thermal maximum of the species (36.4°C) minus the mean body temperature of the simulated lizard. In the simulation, we allowed the following thermoregulatory behaviors: changing its body orientation relative to direct insolation, moving along the specified interval of shade percentage, and climbing from 3 up to 200 cm perch height. Each combination of levels of perch height, year, season, and polygon had a sample size of 150 records. We compared the vegetation cover in three months of the rainy season, and the microclimate temperature and TSM in three months of the dry season. The data to reproduce the results is in the data frame 'Manuscript-data_IVE-LMK-MOB_19-01-2022'. An example of the code in R to get the simulated microclimate and body temperature is in the document 'Data-code_IVE-LMK-MOB_19-01-2022'.