title: Demographic controls of aboveground forest biomass across North America.
abstract: Ecologists have limited understanding of how geographic variation in forest biomass arises from differences in growth and mortality at continental to global scales. Using forest inventories from across North America, we partitioned continental-scale variation in biomass growth and mortality rates of 49 tree species groups into (1) species-independent spatial effects and (2) inherent differences in demographic performance among species. Spatial factors that were separable from species composition explained 83% and 51% of the respective variation in growth and mortality. Moderate additional variation in mortality (26%) was attributable to differences in species composition. Age-dependent biomass models showed that variation in forest biomass can be explained primarily by spatial gradients in growth that were unrelated to species composition. Species-dependent patterns of mortality explained additional variation in biomass, with forests supporting less biomass when dominated by species that are highly susceptible to competition (e.g. Populus spp.) or to biotic disturbances (e.g. Abies balsamea).
authors.affiliation: Department of Biology, University of Regina, 3737 Wascana Pkwy, Regina, SK, S4S 0A2, Canada.|Department of Biology, University of Florida, Gainesville, FL, 32611, USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Vanderwel
authors.affiliation: Faculty of Forestry, University of Toronto, 33 Willcocks St., Toronto, ON, M5S 3B3, Canada.
authors.forename: Hongcheng
authors.initials: H
authors.lastname: Zeng
authors.affiliation: Faculty of Forestry, University of Toronto, 33 Willcocks St., Toronto, ON, M5S 3B3, Canada.
authors.forename: John P
authors.initials: JP
authors.lastname: Caspersen
authors.affiliation: Irstea, UR EMGR, 2 rue de la Papeterie-BP 76, St-Martin-d'Hères, F-38402, France.|Univ. Grenoble Alpes, Grenoble, F-38402, France.
authors.forename: Georges
authors.initials: G
authors.lastname: Kunstler
authors.affiliation: Department of Biology, University of Florida, Gainesville, FL, 32611, USA.
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Lichstein
mesh_terms: D044822:Biodiversity; D018533:Biomass; D017753:Ecosystem; D065928:Forests; D008954:Models, Biological; D009656:North America; D013995:Time; D014197:Trees / Q000254:growth & development / Q000502:physiology*
keywords: biomass; carbon; growth; mortality; productivity; trees