Contrasting patterns for endangered flora revealed by 60-year land-use change analysis

Abstract

Land-use change analysis is widely accepted as a biodiversity conservation tool. However, it has seldom been used in the context of endangered plants. Our aim is to accurately quantify changes in land cover over the last 60 years in a selection of 58 populations of 43 Spanish threatened plants. Consequently, we explain how these changes correlate with major trends in biodiversity conservation such as human demography, ecological gradients or the spatial distribution of plant threats. A semi-automatic classification methodology is used to identify land-cover changes by comparing aerial photographs from 1956 to 2019 in an established radius around field plots. Secondly, information from field plots and external databases was analyzed using GIS layers and PCA statistics. Land use changes have been extensive and diverse. Tree and shrubland area have increased by 717.8 ha (an increase of 1.19 times compared to the initial situation) affecting most of the samples, whereas the urban area has increased by 168.8 ha (at a rate of 49 times from the initial values), although concentrated in certain populations. Land-use changes define two groups in the endangered flora: a first group is related to high human densities, low elevation settings and low in situ protection, while a second group is related to the cessation in human pressure, protected area establishment and increase in forest cover. The increase in forested area could be counterproductive. Urban land-use changes present a more urgent issue, especially for those endangered plants in coastal areas. Finally, high herbivore density and richness compromise endangered plant populations growing at high elevation in protected areas.