Tourist Trampling on a Peripheral Plant Population Restricted to an Urban Natural Area in the Capo Sant'Elia Promontory (Sardinia, W-Mediterranean Basin)

Abstract

Urban natural areas provide important ecological services such as biodiversity conservation, as well as opportunities for people to connect with nature and preserve cultural heritage. However, the increasing demand for access to natural areas and the expansion of human recreational activities, such as hiking and biking, pose threats to these ecosystems, especially for animal and plant species, finally resulting in biodiversity loss. This study explores the intricate link between human trampling, plant density, and the morphological and reproductive characteristics of Globularia alypum L., a plant with a peripheral population in Sardinia restricted to a natural area within an urban context. The study examined trampling effects on 75 plots along a frequently used path crossing the plant's core population. Similar environmental conditions were assumed, with differences attributed to human trampling intensity and plant density, and morphological and reproductive traits were measured within each plot. Our results showed that human trampling caused differences in the morphological traits of plants, whereas, in contrast, reproductive traits are less vulnerable to human trampling than morphological ones. As a result, trampled areas may experience decreased plant recruitment, which can have long-term implications for plant population dynamics. Understanding the relationship between trampling effects and the sensitivity of peripheral plant populations is crucial for effective conservation and management strategies.

Keywords: Globularia alypum L.; Sardinia; human trampling effects; isolated plant population; mediterranean flora; natural urban area; plant conservation.

Figure 1

Plant density at Plot ID (A) and Plot position (B) level.

Figure 2

Morphological plant traits at Plot ID (A–C) and Plot position (D–F) level.

Figure 3

(A): representative habitat where the species grows; (B): Globularia alypum individual; (C): Globularia alypum details.

Figure 4

Representative section of the path where nearby growing Globularia alypum L. Red arrow shows the trampled area of the path.

Figure 5

Exemplary diagram of the layout of the transepts and plots in the experimental design, adopted to analyse the effect of human trampling on the Globularia alypum L. population present at Capo Sant’Elia Promontory (Cagliari, Sardinia).