Abstract

QuestionSoil properties are known to have a profound effect on the geographic distribution of plants. Unusual soils seem to allow species to occur outside their 'typical' (realized) climatic niche. However, the generality of this pattern, and the mechanisms that drive it, are poorly known. Here, we focus on the tendency for some plant species to occur at unusually low elevations on infertile substrates, especially serpentine soils. We ask whether there is a flora-wide trend in the state of California toward lower elevations and warmer thermal limits on infertile serpentine soils than on other soils.LocationState of California, USA.MethodsWe used herbarium data from 19 institutions. We only used species collected from both serpentine and non-serpentine soils. To focus on plant response to recent climate, we discarded records from before 1979. Finally, we discarded records that did not report latitude and longitude. The final data set consisted of 36045 specimens representing 814 species. Latitude and longitude were used to infer elevation, temperature and soil type. We then developed a simulation modelling approach to test for significant differences in elevational and thermal distribution between serpentine and non-serpentine soils.ResultsSerpentine populations are found at lower elevations than non-serpentine populations, at both the low and high ends of elevation distributions (two tailed t-test, P<0.01). This pattern is partially matched by temperature: both high and low temperature data indicate that serpentine populations are limited to less extreme temperatures than non-serpentine populations (two tailed t-test, P<0.01).ConclusionsWe show that there is a flora-wide trend toward lower elevation limits on serpentine soils in the state of California. Temperature data suggest a slightly different pattern, with serpentine plants occupying more moderate temperatures. We suggest that this difference may be due to a decoupling of elevation and temperature in some parts of California. Overall, our results are consistent with two mechanisms of plant range limitation: (1) a biotic mechanism at lower elevations (high temperatures), where serpentine provides a refuge from competition; and (2) an abiotic limit at upper elevations (low temperatures), where the effect of cold is exacerbated by the infertility of serpentine.

Keywords

Serpentine soil; Elevation; Herbarium specimen; Infertile soil; Temperature; Disjunct distribution; Climatic range limits; Thermal limit; Climatic niche; Edaphic; Californian flora

Published in

Journal of Vegetation Science
2014, Volume: 25, number: 3, pages: 873-884
Publisher: WILEY-BLACKWELL

UKÄ Subject classification

Botany


Publication identifier

DOI: https://doi.org/10.1111/jvs.12144

Permanent link to this page (URI)

https://res.slu.se/id/publ/91657