COS 263-2 - The effect of arrested succession on woody seedling abundance and diversity in the Andean cloud forest

Abstract: The Mountain cloud forest (MCF) is a hotspot of biodiversity and one of Earth’s most endangered ecosystems. Non-sustainable agricultural activities are rapidly expanding in the MCF, favoring the rapid colonization of invasive species. In the Andes, the invasive bracken ferns, Pteridium spp., suppress the natural recovery of the MCF by maintaining bracken-invaded areas in a permanently degraded state. One of the limiting factors to the natural regeneration of native plant species include their inability to compete with invasive species. Our research investigates forest recovery in degraded bracken fern-invaded areas, combining field data and remote sensing imagery. Using a high-resolution Planet Dove satellite image (3 m) and segmentation analysis, we defined and mapped the boundaries of bracken fern patches. Our object-based segmentation was able to identify land cover, including bracken fern patches, with high accuracy (overall accuracy: 87%). We then set up plots of 0.5 m and 2 m around the pixels centroid of a Landsat image. Within each plot, we collect field data on the abundance of woody seedlings and take high-resolution drone photos (0.53 - 1.06 cm/pixel). We then used multilevel Bayesian analysis to estimate the abundance of seedlings of native woody plants at different percent cover of bracken ferns in the invaded areas. We expected bracken ferns to inhibit the establishment of seedlings; however, our analysis reveals that seedlings of woody plants respond differently to bracken fern cover. Some distinctive Andean woody plants of taxonomic families like Rubiaceae, Chloranthaceae, Myrtaceae, Combretaceae, and Lauraceae are more likely to be found in forested areas. While Ericaceae, Melastomataceae, and Clusiaceae are more frequent in degraded areas with different percentages of bracken fern coverage. These results demonstrate that bracken fern patches would change species composition, becoming a patchy vegetation mostly composed of bracken fern and bushes with a minimal presence of forest species. Our findings are important for understanding where invasive species limit the seedling establishment and where active restoration is needed to support forest recovery.