TY - JOUR

T1 - Global variation in woodpecker species richness shaped by tree availability

AU - Ilsøe, Sigrid Kistrup

AU - Kissling, W. Daniel

AU - Fjeldså, Jon

AU - Sandel, Brody

AU - Svenning, Jens-Christian

PY - 2017/8

Y1 - 2017/8

N2 - Aim: Species richness patterns are generally thought to be determined by abiotic variables at broad spatial scales, with biotic factors being only important at fine spatial scales. However, many organism groups depend intimately on other organisms, raising questions about this generalization. As an example, woodpeckers (Picidae) are closely associated with trees and woody habitats because of multiple morphological and ecological specializations. In this study, we test whether this strong biotic association causes woodpecker diversity to be closely linked to tree availability at a global scale. Location: Global. Methods: We used spatial and non-spatial regressions to test for relationships between broad-scale woodpecker species richness and predictor variables describing current and deep-time availability of trees, current climate, Quaternary climate change, human impact, topographical heterogeneity and biogeographical region. We further used structural equation models to test for direct and indirect effects of predictor variables. Results: There was a strong positive relationship between woodpecker species richness and current tree cover and annual precipitation, respectively. Precipitation also showed a strong indirect effect on woodpecker richness via the effects on tree availability. Deep-time tree availability, Quaternary climate change, human influence and other abiotic factors showed weaker direct effects. Human influence had a negative effect on tree availability, and hence a negative indirect effect on woodpecker species richness. Main conclusions: Global species richness of woodpeckers is primarily shaped by current tree cover and precipitation, reflecting a strong biotic association between woodpeckers and trees. Human influence can have a negative effect on woodpecker diversity when humans reduce tree availability. Hence, woodpeckers exemplify how broad-scale diversity patterns are predominantly shaped by a biotic factor, and how climate and human influence can have indirect effects on animal biodiversity via the effects on tree availability and forest cover.

AB - Aim: Species richness patterns are generally thought to be determined by abiotic variables at broad spatial scales, with biotic factors being only important at fine spatial scales. However, many organism groups depend intimately on other organisms, raising questions about this generalization. As an example, woodpeckers (Picidae) are closely associated with trees and woody habitats because of multiple morphological and ecological specializations. In this study, we test whether this strong biotic association causes woodpecker diversity to be closely linked to tree availability at a global scale. Location: Global. Methods: We used spatial and non-spatial regressions to test for relationships between broad-scale woodpecker species richness and predictor variables describing current and deep-time availability of trees, current climate, Quaternary climate change, human impact, topographical heterogeneity and biogeographical region. We further used structural equation models to test for direct and indirect effects of predictor variables. Results: There was a strong positive relationship between woodpecker species richness and current tree cover and annual precipitation, respectively. Precipitation also showed a strong indirect effect on woodpecker richness via the effects on tree availability. Deep-time tree availability, Quaternary climate change, human influence and other abiotic factors showed weaker direct effects. Human influence had a negative effect on tree availability, and hence a negative indirect effect on woodpecker species richness. Main conclusions: Global species richness of woodpeckers is primarily shaped by current tree cover and precipitation, reflecting a strong biotic association between woodpeckers and trees. Human influence can have a negative effect on woodpecker diversity when humans reduce tree availability. Hence, woodpeckers exemplify how broad-scale diversity patterns are predominantly shaped by a biotic factor, and how climate and human influence can have indirect effects on animal biodiversity via the effects on tree availability and forest cover.

KW - arboreal avian guild

KW - biodiversity

KW - biotic modifiers

KW - birds

KW - forests

KW - habitat loss

KW - Piciformes

KW - plant-bird interactions

KW - species-habitat associations

KW - vegetation effects

UR - http://www.scopus.com/inward/record.url?scp=85018584256&partnerID=8YFLogxK

U2 - 10.1111/jbi.13009

DO - 10.1111/jbi.13009

M3 - Journal article

AN - SCOPUS:85018584256

VL - 44

SP - 1824

EP - 1835

JO - Journal of Biogeography

JF - Journal of Biogeography

SN - 0305-0270

IS - 8

ER -