Global patterns and predictors of stem CO2 efflux in forest ecosystems.

摘要: Stem CO2 efflux (ES) plays an important role in the carbon balance of forest ecosystems. However, its primary controls at global scale are poorly understood and observation-based estimates lacking. We synthesized data from 121 published studies across ecosystems examined relationships between annual ES biotic abiotic factors individual, biome, scales, developed a gridded estimate ES. tested following hypotheses: (1) Leaf area index (LAI) will be highly correlated with biome scales; (2) there parallel patterns stem root effluxes (RA) all forests; (3) decline age; (4) LAI coupled mean temperature (MAT) precipitation (MAP) sufficient to predict forests different regions. Positive linear were found LAI, as well gross production (GPP), net (NPP), wood NPP, soil (RS), RA. Annual was RA temperate after controlling for GPP MAT, suggesting other additional contributed relationship. tended decrease stand age. index, MAT MAP, predicted 74% variation scales. Our statistical model estimated 6.7 � 1.1 Pg C yr 1 over period 2000–2012 little interannual variability. Modeled 71 43, 270 103, 420 134 g m 2 boreal, temperate, tropical forests, respectively. recommend that future report standardized constant temperature, incorporate more manipulative treatments, such fertilization drought, whenever possible, simultaneously measure both aboveground belowground fluxes.