TY - JOUR

T1 - Mechanisms behind elevational plant species richness patterns revealed by a trait-based approach

AU - Ratier Backes, Amanda

AU - Römermann, Christine

AU - Alexander, Jake M.

AU - Arévalo, José Ramón

AU - Keil, Petr

AU - Padrón-Mederos, Miguel Antonio

AU - Trogisch, Stefan

AU - Haider, Sylvia

N1 - Publisher Copyright: © 2022 The Authors. Journal of Vegetation Science published by John Wiley & Sons Ltd on behalf of International Association for Vegetation Science.

PY - 2023/1/1

Y1 - 2023/1/1

N2 - Aims: Elevational patterns of plant species richness may be caused by multiple underlying mechanisms, and the same pattern can be predicted by different mechanisms. Using the steep elevational gradient of Tenerife as a model system, we aimed to test if the application of a trait-based approach can help disentangle the role of potential mechanisms behind local elevational plant species richness patterns. Location: Tenerife, Canary Islands, Spain. Methods: Based on vegetation relevés from natural vegetation and disturbed roadside habitat, along an elevational gradient of 2300 m, we observed a peak of plant species richness in the lowest third of the gradient. We considered three mechanisms potentially shaping this pattern: environmental filtering (temperature and precipitation), effects of area and disturbance. For these mechanisms, we hypothesized a distinct pattern of functional trait–elevation relationships. These were tested with in-situ data of nine functional leaf traits, from which we calculated community-weighted means (CWM) of traits and functional diversity (Rao's Q). Results: While species richness was significantly positively correlated with temperature, area and disturbance, filtering through temperature was the only mechanism for which we could confirm most of our mechanism-specific hypotheses about elevational trait changes: with increasing elevation, CWMs of most traits indicated shifts from acquisitive to conservative growth strategies, and functional diversity decreased. The shift of growth strategies also supported the disturbance effect, as we found overall more acquisitive communities at roadsides compared to natural habitats. Conclusions: Our results indicate that simple correlations between species richness and abiotic variables are not necessarily causal. Additional testing of mechanism-specific hypotheses for elevational patterns of both CWMs and functional diversity can help distinguishing between correlational and mechanistic relationships between species richness and environmental variables. The trait-based framework presented here can be fruitfully applied to better understand species richness patterns in other regions and across other types of environmental gradients.

AB - Aims: Elevational patterns of plant species richness may be caused by multiple underlying mechanisms, and the same pattern can be predicted by different mechanisms. Using the steep elevational gradient of Tenerife as a model system, we aimed to test if the application of a trait-based approach can help disentangle the role of potential mechanisms behind local elevational plant species richness patterns. Location: Tenerife, Canary Islands, Spain. Methods: Based on vegetation relevés from natural vegetation and disturbed roadside habitat, along an elevational gradient of 2300 m, we observed a peak of plant species richness in the lowest third of the gradient. We considered three mechanisms potentially shaping this pattern: environmental filtering (temperature and precipitation), effects of area and disturbance. For these mechanisms, we hypothesized a distinct pattern of functional trait–elevation relationships. These were tested with in-situ data of nine functional leaf traits, from which we calculated community-weighted means (CWM) of traits and functional diversity (Rao's Q). Results: While species richness was significantly positively correlated with temperature, area and disturbance, filtering through temperature was the only mechanism for which we could confirm most of our mechanism-specific hypotheses about elevational trait changes: with increasing elevation, CWMs of most traits indicated shifts from acquisitive to conservative growth strategies, and functional diversity decreased. The shift of growth strategies also supported the disturbance effect, as we found overall more acquisitive communities at roadsides compared to natural habitats. Conclusions: Our results indicate that simple correlations between species richness and abiotic variables are not necessarily causal. Additional testing of mechanism-specific hypotheses for elevational patterns of both CWMs and functional diversity can help distinguishing between correlational and mechanistic relationships between species richness and environmental variables. The trait-based framework presented here can be fruitfully applied to better understand species richness patterns in other regions and across other types of environmental gradients.

KW - altitude

KW - biodiversity

KW - community-weighted mean

KW - environmental filtering

KW - functional diversity

KW - functional traits

KW - mountain biogeography

KW - species richness

KW - Biology

UR - http://www.scopus.com/inward/record.url?scp=85149823533&partnerID=8YFLogxK

U2 - 10.1111/jvs.13171

DO - 10.1111/jvs.13171

M3 - Journal articles

AN - SCOPUS:85149823533

VL - 34

JO - Journal of Vegetation Science

JF - Journal of Vegetation Science

SN - 1100-9233

IS - 1

M1 - e13171

ER -