Abstract:

Forest gaps are an important disturbance in forest communities and impact the composition of understory species. The research on the relationship between the spatial patterns of forest canopy gap and diversity indices of understory plants is of great significance to understand the impcat between forest canopy gap and the biodiversity of understory plants. This will help to further understand community dynamics and also protect species diversity. In this study, three tropical rainforests with a size of one hectare were randomly selected in the Xishuangbanna tropical rain forest. A light and small six-rotor UAs was mounted with a Sony ILCE-A7r visible light sensor to obtain high-definition digital images of each plot. Digital surface elevation models and the topographic data of each plot were used to determine the distribution type of canopy gaps in each plot and to extract landscape pattern indices. Based on ground-based survey data, a statistical survey of plant diversity under each forest canopy gap was carried out to analyze the relationship between the spatial distribution of forest gaps and plant diversity. Results show that the tropical rain forest gaps in Xishuangbanna are large and have a scattered spatial distribution. The spatial characteristics indices, such as the shape and complexity index, and the area were significantly positively correlated with the diversity of understory plants. The size of the forest canopy gap had a more significant impact on the plant diversity than the shape. After the area reaches a certain level, the shape and complexity index of the gap is relative to the area factor. The impact on diversity of understory plants is more severe, and all forest gaps tend to recover from the top communities in their respective plots.

Key words: canopy gap, landscape spatial pattern, plant diversity, landscape pattern metrics, near-surface remote sensing, UAV