2.1. Study site

The study was conducted in Eastern Andean Cordillera in Bogotá city, Colombia, in the subpáramo Cerro Aguanoso (4° 34′ 28.67″ N, 74° 02′ 8.48″ W) (Fig. 1a). This subpáramo is located in the Bosque Oriental Forest Reserve, part of the Estructura Ecologica Principal of Bogotá, a strategic ecosystem with a network of environmental corridors whose primary components are the system of protected areas, urban parks, ecological corridors (van der Hammen and Andrade, 2003). The annual mean temperature fluctuates between 8 and 12 °C, while mean annual precipitation ranges between 1000 and 1500 mm with a bimodal distribution pattern. The wet season between December and March is characterized by less than 100 mm monthly precipitation. Relative humidity of 43.6% in the wet season. The elevation of the subpáramo in reserve ranges from 3000 to 3500 m a.s.l (IDEAM, 2007; CAR, 2016; Peyre et al., 2018). The area has a black humid soils with an acid pH (value < 5.5), as is typical for the high and humid regions of the páramos.

Location of the study area in the Bosque Oriental Forest Reserve, Colombia. (a) The geographic location of the burned site (Cerro Aguanoso, B) and unburned site (Cerro Alto de la Viga, UB). (b) Schematic distribution of plots along the sampling transects; orange rectangles grey with represent the position of plots. (c) In the sampling period, the black boxes represent the sampling months and season, blue is the wet season, and orange is the dry season.

During the extremely dry conditions generated by the 2015–2016 El Niño climatic event (Huang et al., 2016), between January and February 2016. A forest fire broke out in the Bosque Oriental Forest Reserve, affecting around 128 ha (Rodríguez and Pinilla, 2022), of which 8.23 ha correspond to low vegetation associated with the Cerro Aguanoso subpáramo. The vegetation was affected, the fire affected the woody plants, and their stems were charred to a great extent. In addition, the fire affected the surface cover of the soil, consuming the litter, as well as mosses and herbaceous plants. Rodríguez and Pinilla (2022) determined the severity of burning where 0.92 ha presented low severity, 4.82 ha moderate severity, and 2.49 ha medium to high severity. For this, the authors used the normalized difference vegetation index (NDVI), which shows that the vigor of 2016 was low (0.4–0.54) and that, five years after the fire, 2021 increased to medium (0.54–0.68), which reflects a uniformity in the area affected by the fire and a decrease in patches.