Investigating elevational gradients of species richness in a Mediterranean plant hotspot using a published flora

Michele Di Musciano,Lorenzo Spina,Juri Nascimbene,Marco D'Agostino,Kuber P Bhatta,Piero Zannini,Ole R Vetaas,Angelino Carta,Chiara Ferrara,Lorenzo Peruzzi,Alessandro Chiarucci

doi:10.21425/f5fbg50007

Abstract

The Apuan Alps are one of the most peculiar mountain chain in the Mediterranean, being very close to the coastline and reaching an elevation of almost 2000 m. Based on published flora, we investigated the distribution of plant species richness along the whole elevational gradient of this chain considering: (i) all species, (ii) endemic versus alien species; and (iii) functional groups of species based on Raunkiær life forms (RLF). Generalized Linear Models (GLMs) were used to analyse richness patterns along the elevational gradient, and elevational richness models versus the area of the elevational belts were fitted to test the effect of surface area. Our results showed decreasing species richness with increasing elevation. In contrast, endemic species richness increased along the elevational gradient. Alien species were mainly distributed at low elevations, but this result should be taken with caution since we used historical data. Species life forms were not equally distributed along the elevation gradient: chamaephytes and hemicryptophytes were the richest groups at high elevations, while therophytes showed highest species richness at low elevations. Our findings suggest that in the Apuan Alps there is a major elevational gradient in species composition that could reflect plant evolutionary history. Furthermore, we highlight the key role of published floras as a relevant source of biodiversity data.

Highlights

Patterns of plant species richness have always been a topic of interest in biogeography and ecology (Pianka 1966, Huston and Huston 1994, Lomolino 2001, Whittaker et al 2001)
Plant elevation patterns in the Apuan Alps the Apuan Alps (Central Italy) to model patterns of species richness for: (i) native species, (ii) endemic and alien species separately, and (iii) functional groups of species based on Raunkiær life forms (RLF; Raunkiær 1934)
We investigated how species richness varies along the elevational gradient, both for the whole flora and for endemic and alien species, as well as for different Raunkiaer’s life forms

Summary

Introduction

Patterns of plant species richness have always been a topic of interest in biogeography and ecology (Pianka 1966, Huston and Huston 1994, Lomolino 2001, Whittaker et al 2001). An increase in species richness with increasing area is one of the most robust ecological generalizations (Rosenzweig 1995, Lomolino 2000), and a vast literature has been published on species−area relationships The two most investigated environmental gradients related to species richness patterns are latitude and elevation. The variation of species richness along elevational gradients has been documented for a variety of taxa and geographical areas (see e.g., Terborgh 1977, Stevens 1992, Rahbek 1995, Bhattarai and Vetaas 2003, Grytnes 2003, Bhattarai et al 2004, Bhattarai and Vetaas 2005, Carpenter 2005, McCain and Grytnes 2010, Bhatta et al 2018). The two most frequent patterns that have emerged: a monotonic decrease in species richness as a function of elevation (Yoda 1968, MacArthur 1972, Stevens 1992, Liang et al 2020, Subedi et al 2020) and a hump‐shaped relationship, with a peak in species richness at intermediate elevations (Grytnes and Vetaas 2002, Rahbek 2005, Bhattarai and Vetaas 2006, Ibanez et al 2016)

Methods

Results

Discussion

Conclusion