The Hitchhiker’s guide to island endemism: biodiversity and endemic perennial plant species in roadside and surrounding vegetation

Irl, Severin D. H.; Steinbauer, Manuel J.; Epperlein, Lilith R.F.; Harter, David E. V.; Jentsch, Anke; Pätz, Susanne; Wohlfart, Christian; Beierkuhnlein, Carl

doi:10.1007/s10531-014-0722-6

Cited by 17 publications

(21 citation statements)

References 40 publications

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“…On the one hand, steep and inaccessible areas might offer ‘safe sites’ for endemics from introduced herbivores (Irl et al . ,b) because endemics are preferentially browsed by introduced herbivores (Garzón‐Machado et al . ; Irl et al .…”

Section: Discussionmentioning

confidence: 99%

Climate vs. topography – spatial patterns of plant species diversity and endemism on a high‐elevation island

et al. 2015

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Summary Climate and topography are among the most fundamental drivers of plant diversity. Here, we assessed the importance of climate and topography in explaining diversity patterns of species richness, endemic richness and endemicity on the landscape scale of an oceanic island and evaluated the independent contribution of climatic and topographic variables to spatial diversity patterns. We constructed a presence/absence matrix of perennial endemic and native vascular plant species (including subspecies) in 890 plots on the environmentally very heterogeneous island of La Palma, Canary Islands. Species richness, endemic richness and endemicity were recorded, interpolated and related to climate (i.e. variables describing temperature, precipitation, variability and climatic rarity) and topography (i.e. topographic complexity, solar radiation, geologic age, slope and aspect). We used multimodel inference, spatial autoregressive models, variance partitioning and linear regression kriging as statistical methods. Species richness is best explained by both climatic and topographic variables. Topographic variables (esp. topographic complexity and solar radiation) explain endemic richness, and climatic variables (esp. elevation/temperature and rainfall seasonality) explain endemicity. Spatial patterns of species richness, endemic richness and endemicity were in part geographically decoupled from each other. Synthesis. We identified several topography‐dependent processes ranging from evolutionary processes (micro‐refugia, in situ speciation, pre‐adaptation to rupicolous conditions, dispersal limitations) to human‐induced influences (introduced herbivores, fire, land use) that possibly shape the endemic richness pattern of La Palma. In contrast, climate mainly drives endemicity, which is connected to ecological speciation and specialization to local conditions. We highlight the importance of incorporating climatic variability into future studies of plant species diversity and endemism. The spatial incongruence in hot spots of species richness, endemic richness and endemicity emphasizes the need for an integrated conservation approach acknowledging different diversity measures to protect the complete spectrum of diversity. High‐elevation islands such as La Palma are highly suitable to study drivers of diversity and endemism, as they offer environmental gradients of continental magnitude on the landscape scale of a single climatic mini‐continent and a large array of in situ‐speciated endemics.

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Section: Discussionmentioning

confidence: 99%

Climate vs. topography – spatial patterns of plant species diversity and endemism on a high‐elevation island

et al. 2015

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“…We calculated distance to the nearest road and distance to the nearest city from road and urbanization maps, respectively (but see Irl, Steinbauer, Epperlein et al, 2014 for effects of roads on endemics). We developed a cultivation index that indicates whether a plot lies within the zone of cultivation (agriculture, settlements, etc.)…”

Section: Environmental and Anthropogenic Datamentioning

confidence: 99%

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

Irl

Schweiger

Medina

et al. 2017

Diversity and Distributions

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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.

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“…Elevation and anthropogenic disturbance, such as the presence of roads, may strongly affect the distribution of native and alien species (Pauchard and Alaback 2004, Marini et al 2009, Pauchard et al 2009, Marini et al 2013, Irl et al 2014. Assessing patterns of plant species richness along roads and elevation gradients can provide important insights into the effects of anthropogenic activities on plant communities, especially as far as island and mountain ecosystems are concerned.…”

Section: The Role Of Elevation and Human Impact On The Distribution Omentioning

confidence: 99%

“…In particular, variables such as high humidity (derived from mean annual precipitation plus trade wind interception), low thermal stress, and high productivity tend to reach a maximum at intermediate elevations in the Canary Islands (Arévalo et al 2005). Drought stress characterizing both low (sea level) and high elevations, and low temperatures at high elevation represent major environmental filters to the establishment of a species (Irl et al 2014). Thus, plant communities occurring at low or high elevations may support less species than those at intermediate elevations.…”

Section: The Role Of Elevation and Human Impact On The Distribution Omentioning

confidence: 99%

“…In steep mountain areas and on high-elevation oceanic islands, where roads are cut into slopes, these environmental factors could have a high relevance (Irl et al 2014). Beside influencing the environmental conditions in their proximity, the impact of roads on plant communities typically varies with the distance from the road edge (Spellerberg 1998).…”

Section: The Role Of Elevation and Human Impact On The Distribution Omentioning

confidence: 99%

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Distributional patterns of endemic, native and alien species along a roadside elevation gradient in Tenerife, Canary Islands

et al. 2015

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Abstract:Invasion by alien plant species may be rapid and aggressive, causing erosion of local biodiversity. This is particularly true for islands, where natural and anthropogenic corridors promote the rapid spread of invasive plants. Although evidence shows that corridors may facilitate plant invasions, the question of how their importance in the spread of alien species varies along environmental gradients deserves more attention. Here, we addressed this issue by examining diversity patterns (species richness of endemic, native and alien species) along and across roads, along an elevation gradient from sea-level up to 2050 m a.s.l. in Tenerife (Canary Islands, Spain), at multiple spatial scales. Species richness was assessed using a multi-scale sampling design consisting of 59 T-transects of 150 m × 2 m, along three major roads each placed over the whole elevation gradient. Each transect was composed of three sections of five plots each: Section 1 was located on the road edges, Section 2 at intermediate distance, and Section 3 far from the road edge, the latter representing the "native community" less affected by road-specific disturbance. The effect of elevation and distance from roadsides was evaluated for the three groups of species (endemic, native and alien species), using parametric and non-parametric regression analyses as well as additive diversity partitioning. Differences among roads explained the majority of the variation in alien species richness and composition. Patterns in alien species richness were also affected by elevation, with a decline in richness with increasing elevation and no alien species recorded at high elevations. Elevation was the most important factor determining patterns in endemic and native species. These findings confirm that climate filtering reflected in varying patterns along elevational gradients is an important determinant of the richness of alien species (which are not adapted to high elevations), while anthropogenic pressures may explain the richness of alien species at low elevation.

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The Hitchhiker’s guide to island endemism: biodiversity and endemic perennial plant species in roadside and surrounding vegetation

Cited by 17 publications

References 40 publications

Climate vs. topography – spatial patterns of plant species diversity and endemism on a high‐elevation island

Climate vs. topography – spatial patterns of plant species diversity and endemism on a high‐elevation island

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

Distributional patterns of endemic, native and alien species along a roadside elevation gradient in Tenerife, Canary Islands

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