An island view of endemic rarity—Environmental drivers and consequences for nature conservation

Abstract

Aim: Rarity-an important measure for conservation biogeography-can vary over many orders of magnitude. However, it is unclear which regional-scale abiotic conditions drive processes affecting rarity of endemic species on islands. To support conservation efforts, we (1) assess the main abiotic drivers of endemic rarity, (2) determine how well existing protected areas (PAs) coincide with hotspots of endemic rarity and (3) introduce and evaluate a new hypervolume-based rarity estimator. Location: La Palma (Canary Islands). Methods:We recorded all present endemic vascular plant species in 1,212 plots covering the entire island. We calculated endemic rarity (corrected range-rarity richness for endemics) using a rarity estimation approach based on kernel density estimations (hypervolume approach). We performed a sensitivity analysis based on multiple linear regressions and relative importance estimations of environmental drivers to estimate the performance of the hypervolume-based rarity estimation compared to standard methods (occurrence frequency, convex hulls, alpha hulls).Results: Climate variables (mean annual temperature, climatic rarity, precipitation variability) best explained archipelago endemic (AE) and single-island endemic (SIE) rarity.Existing PAs covered the majority of AE and SIE rarity, especially national and natural parks as well as the Natura 2000 sites. In our study system, hypervolumes performed better than standard measures of range size.Main conclusion: Both AE and SIE rarity on La Palma show a clear spatial pattern, with hotspots of endemic rarity found at high elevations and in rare climates, presumably owing to geographical and climatic constraints and possibly anthropogenic pressure (e.g., land use, introduced herbivores, fire). Areas of high rarity estimates coincide with the distribution and extent of PAs on La Palma, especially since the recent addition of the Natura 2000 sites. The hypervolume approach is a promising tool to estimate species range sizes, and can be applied on all scales where point/plot data are available.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Graminoid Invasion in an Insular Endemism Hotspot and Its Protected Areas

“…The latter is in accordance with general distribution patterns of endemic and invasive plant species on high-elevation islands [33,69]. While high elevations host the highest number of endemic species [69] and the aggregation of rare endemics most vulnerable to extinction aggregate there as well [59], non-native species richness peaks at elevations around 500 m [69]. Mean elevation of projected suitable habitat for P. setaceum was 543 m and matches this pattern quite precisely.…”

“…To evaluate modeling results in combination with designated areas of different protection status we considered the locations of the core, buffer, and transition zone of the biosphere reserve [59], Natura 2000 sites defined by the EU Habitat Directive [60], and nationally/ regionally designated protected areas, which include the national park, protected landscapes, natural parks, natural monuments, sites of scientific interest, and nature reserves [61]. The vector data was rasterized and scaled to 500 × 500 m. We calculated the projected suitable habitat for P. setaceum within designated areas of each protection status (cover in % and km 2 ).…”

The Role of Climate and Topography in Shaping the Diversity of Plant Communities in Cabo Verde Islands

“…The shrub formations of Cabo Verde (Figure 2E,F) are mainly found in zones of medium to high elevations above 400 m, and the levels of endemism increase with elevation, as proposed by Steinbauer et al [51]. The shrub vegetation is dominated by endemic species, showing a comparable pattern to Canary Islands [52,53] with a clear spatial pattern, with hotspots of endemic rarity found at high elevations and in specific habitats, namely in northeast-facing cliffs, of the Natural Parks of Moroços, Cova, and Ribeira da Torre (Santo Antão); Monte Gordo (São Nicolau); Serra da Malagueta (Santiago); Monte Verde (São Vicente); and Chã das Caldeiras (Fogo Island) [54].…”

Spatiotemporal dynamics of plant diversity and endemism during primary succession on an oceanic‐volcanic island

“…An expert in bryophytes (Eduard Hertel, Ecological Botanical Garden, University of Bayreuth) was consulted for species not identified with certainty. On La Palma, both alien richness and endemic richness generally decrease with elevation (Steinbauer et al., ), while rare endemics aggregate at higher elevations (Irl et al., ).…”