Abstract
Rarity is a complex and central concept in ecology and conservation biology. e rarity of species can be defined along multiple axes and at different scales, e.g., abundance at the local or community scale, frequency of occurrence at the landscape or habitat scale, and geographic range and niche (or habitat) breath at the regional to global scale (Preston, 1948; Rabinowitz et al., 1986; Kunin and Gaston, 1993, 1997). Species with low local abundance or frequencies, or small geographical range sizes or niche breadths, are likely to be more susceptible to demographic or environmental extinction drivers (e.g., Matthies et al., 2004; Burns and Neufeld, 2009; Staude et al., 2020). Understanding the drivers of species rarity patterns is therefore recognized as an important issue in ecology and conservation biology. e multiple axes of rarity typically correlate with each other. For example, locally rare species oen are less frequent on a landscape scale and have smaller geographical range sizes and niche breadths on a regional scale (Price and Wagner, 2004; Davidar et al., 2008; Arellano et al., 2015). Rare species are therefore likely to be rare at all local, landscape, and regional scales, which compounds extinction risk. However, large variation exists around those broad trends (i.e., locally rare species can be common at landscape or regional scales and vice versa), and factors driving rarity may differ across spatial scales. Many studies have shown that species ecological traits, notably those related to plant size and dispersal, affect the rarity/commonness patterns of plant species (e.g.