Does probability of occurrence relate to population dynamics?
Hutchinson defined species' realized niche as the set of environmental conditions in which populations can persist in the presence of competitors. In terms of demography, the realized niche corresponds to the environments where the intrinsic growth rate (r) of populations is positive. Observed species occurrences should reflect the realized niche when additional processes like dispersal and local extinction lags do not have overwhelming effects. Despite the foundational nature of these ideas, quantitative assessments of the relationship between range-wide demographic performance and occurrence probability have not been made. This assessment is needed both to improve our conceptual understanding of species' niches and ranges and to develop reliable mechanistic models of species geographic distributions that incorporate demography and species interactions. The objective of this study is to analyse how demographic parameters (intrinsic growth raterand carrying capacityK) and population density (N) relate to occurrence probability (Pocc). We hypothesized that these relationships vary with species' competitive ability. Demographic parameters, density, and occurrence probability were estimated for 108 tree species from four temperate forest inventory surveys (Québec, Western US, France and Switzerland). We used published information of shade tolerance as indicators of light competition strategy, assuming that high tolerance denotes high competitive capacity in stable forest environments. Interestingly, relationships between demographic parameters and occurrence probability did not vary substantially across degrees of shade tolerance and regions. Although they were influenced by the uncertainty in the estimation of the demographic parameters, we found thatrwas generally negatively correlated withPocc, whileN,and for most regions K, was generally positively correlated withPocc. Thus, in temperate forest trees the regions of highest occurrence probability are those with high densities but slow intrinsic population growth rates. The uncertain relationships between demography and occurrence probability suggests caution when linking species distribution and demographic models.
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France.
Wilfried
W
Thuiller
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France.
Tamara
T
Münkemüller
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France.
Katja H
KH
Schiffers
Univ. Grenoble Alpes, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France ; CNRS, Laboratoire d'Ecologie Alpine (LECA), F-38000 Grenoble, France.
Damien
D
Georges
Dep. of Conservation Biology, Vegetation- and Landscape Ecology, Faculty Centre of Biodiversity, Rennweg 14, 1030 Vienna.
Stefan
S
Dullinger
Department of Biology, Grinnell College, Grinnell, IA, USA 50112.
Vincent M
VM
Eckhart
US. Geological Survey, Utah Cooperative Fish and Wildlife Research Unit and Wildland Resources, Utah State Univ., Logan, UT 84322-5290, USA.
Thomas C
TC
Edwards
Université du Québec à Rimouski, Département de Biologie, Chimie et Géographie, 300 Allée des Ursulines, Québec G5L 3A1, Canada.
Dominique
D
Gravel
Irstea, UR Mountain Ecosystems, St-Martin-d'Hères, France ; Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia.
Georges
G
Kunstler
Smithsonian Environmental Research Center, Edgewater, 21307-0028, MD, USA.
Cory
C
Merow
Center for Population Biology, Department of Evolution and Ecology, University of California, Davis, CA, 95616, USA.
Kara
K
Moore
AgroParisTech, UMR1092, Laboratoire d'Étude des Ressources Forêt-Bois (LERFoB), ENGREF, Nancy Cedex, France ; INRA, UMR1092, Laboratoire d'Étude des Ressources Forêt-Bois (LERFoB), Centre INRA de Nancy, Champenoux, France.
Christian
C
Piedallu
Université du Québec à Rimouski, Département de Biologie, Chimie et Géographie, 300 Allée des Ursulines, Québec G5L 3A1, Canada.
Steve
S
Vissault
Landscape Dynamics Unit, Swiss Federal Research Institute WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland.
Niklaus E
NE
Zimmermann
Landscape Dynamics Unit, Swiss Federal Research Institute WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland ; Plant Ecology and Nature Conservation, Institute for Biochemistry and Biology, University of Potsdam, Maulbeerallee 2, D-14469 Potsdam, Germany.
Damaris
D
Zurell
Institut des Sciences de l'Evolution de Montpellier, UMR-CNRS 5554, Université Montpellier II, 34095 Montpellier cedex 5, France ; Institute of Landscape and Plant Ecology, University of Hohenheim, 70593 Stuttgart, Germany.
Frank M
FM
Schurr