Estudio del género Graphis en el bosque seco tropical del municipio de Girardot- Cundinamarca, Colombia, como modelo de análisis de pérdida de biodiversidad por cambio climático

Abstract

This study documented the diversity of the genus Graphis in three areas of the Tropical Dry Forest (TDF) in the municipality of Girardot, Cundinamarca, combining traditional sampling methods (Sipman, 1996) with species distribution modeling under future high-pollution climate scenarios. Given the high threat faced by TDFs due to deforestation and fragmentation, detailed information about their biodiversity is crucial for conservation. The results revealed three species new to science: Graphis epigraphis, Graphis maryae, and Graphis girardotensis. The methodology included the establishment of sampling areas, collection, identification, and deposition of specimens in the UDBC Herbarium – Non-Vascular Section. Among the reported species of the genus, higher diversity was observed between the Eastern and Western Cordilleras, in contrast with lower diversity in the Orinoquía region (Colombian Llanos), which is attributed to the scarcity of records in the latter. Alpha diversity indices suggested high diversity in lowland areas, with dominance by a few species (Simpson index), while beta diversity indices revealed considerable differentiation among Graphis communities across the sampling zones. The potential distribution modeling, conducted using the Wallace software, occurrence data, and climatic variables from WorldClim under the Maxent algorithm and the SSP 5-8.5 (2021–2040) climate scenario from the ACCESS-CM2 model (high emissions), showed an increase in the presence of Graphis anfractuosa towards higher elevations of the mountain ranges due to rising temperatures and droughts. G. caesiella and G. furcata showed trends of expansion towards the Llanos and the Middle Magdalena Valley, respectively. The lack of data prevented modeling for other species. The increase in presence at higher elevations raises questions about the effects of climate change on lichen communities and the potential loss through the turnover of species less tolerant to these environmental variables. This research georeferenced Graphis species in Girardot for the first time and developed an (unpublished) field guide including morphological, chemical, and spore information to facilitate the identification and recording of species. It concludes with the need to expand studies on TDF diversity before climate change significantly reshapes these areas, as highlighted by the discovery of three new species that demonstrate the still unknown high diversity.