Carbon isotopic signatures of soil organic matter correlates with leaf area index across woody biomes

LADD B.; PERI P.L.; PEPPER D.A.; SILVA L.C.R.; SHEILF D.; BONSER S.P.; LAFFAN S.W.;; AMELUNG W.; EKBLAD A.; ELIASSON P.; BAHAMONDE H.A.; DUARTE-GUARDIA S.; BIRD M.

JOURNAL OF ECOLOGY (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 102 p. 1606 - 1611

0022-0477

1. Leaf area index (LAI), a measure of canopy density, is a key variable for modelling and understanding primary productivity, and also water use and energy exchange  in forest ecosystems.  However, LAI varies considerably with phenology and disturbance patterns so alternative approaches to quantifying stand level processes should be considered.  The carbon isotope composition of soil organic matter (ä13CSOM) provides a time-integrated, productivity-weighted measure of physiological and stand-level processes, reflecting biomass deposition from seasonal to decadal time scales. 2. Our primary aim was to explore how well LAI correlates with ä13CSOM across biomes. 3. Using a global data set spanning large environmental gradients in tropical, temperate and boreal forest and woodland we assess the strength of the correlation between LAI and ä13CSOM; we also assess climatic variables derived from the WorldClim database.  4. We found that LAI was correlated to ä13CSOM, Mean Temperature of the Wettest Quarter, Mean Precipitation of Warmest Quarter and Solar Radiation across and within biomes.  5. Synthesis. Our results demonstrate that ä13CSOM values can provide spatially explicit estimates of LAI and could therefore serve as a surrogate for productivity and water use. While ä13CSOM has traditionally been used to reconstruct the relative abundance of C3 vs. C4 species, the results of this study demonstrate that within stable C3- or C4- dominated biomes ä13CSOM can provide additional insights.  The fact that LAI is strongly correlated to ä13CSOM may allow for a more nuanced interpretation of paleosol 13C values and the fossil record.