title: Is leaf dry matter content a better predictor of soil fertility than specific leaf area?
abstract: OBJECTIVE
  Specific leaf area (SLA), a key element of the 'worldwide leaf economics spectrum', is the preferred 'soft' plant trait for assessing soil fertility. SLA is a function of leaf dry matter content (LDMC) and leaf thickness (LT). The first, LDMC, defines leaf construction costs and can be used instead of SLA. However, LT identifies shade at its lowest extreme and succulence at its highest, and is not related to soil fertility. Why then is SLA more frequently used as a predictor of soil fertility than LDMC?
  
  
  METHODS
  SLA, LDMC and LT were measured and leaf density (LD) estimated for almost 2000 species, and the capacity of LD to predict LDMC was examined, as was the relative contribution of LDMC and LT to the expression of SLA. Subsequently, the relationships between SLA, LDMC and LT with respect to soil fertility and shade were described.
  
  
  RESULTS
  Although LD is strongly related to LDMC, and LDMC and LT each contribute equally to the expression of SLA, the exact relationships differ between ecological groupings. LDMC predicts leaf nitrogen content and soil fertility but, because LT primarily varies with light intensity, SLA increases in response to both increased shade and increased fertility.
  
  
  CONCLUSIONS
  Gradients of soil fertility are frequently also gradients of biomass accumulation with reduced irradiance lower in the canopy. Therefore, SLA, which includes both fertility and shade components, may often discriminate better between communities or treatments than LDMC. However, LDMC should always be the preferred trait for assessing gradients of soil fertility uncoupled from shade. Nevertheless, because leaves multitask, individual leaf traits do not necessarily exhibit exact functional equivalence between species. In consequence, rather than using a single stand-alone predictor, multivariate analyses using several leaf traits is recommended.
authors.affiliation: Station House, Leadmill, Hathersage, Hope Valley S32 1BA, UK. j.hodgson@sheffield.ac.uk
authors.forename: J G
authors.initials: JG
authors.lastname: Hodgson
authors.forename: G
authors.initials: G
authors.lastname: Montserrat-Martí
authors.forename: M
authors.initials: M
authors.lastname: Charles
authors.forename: G
authors.initials: G
authors.lastname: Jones
authors.forename: P
authors.initials: P
authors.lastname: Wilson
authors.forename: B
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authors.lastname: Shipley
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authors.lastname: Sharafi
authors.forename: B E L
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authors.lastname: Cerabolini
authors.forename: J H C
authors.initials: JH
authors.lastname: Cornelissen
authors.forename: S R
authors.initials: SR
authors.lastname: Band
authors.forename: A
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authors.lastname: Bogard
authors.forename: P
authors.initials: P
authors.lastname: Castro-Díez
authors.forename: J
authors.initials: J
authors.lastname: Guerrero-Campo
authors.forename: C
authors.initials: C
authors.lastname: Palmer
authors.forename: M C
authors.initials: MC
authors.lastname: Pérez-Rontomé
authors.forename: G
authors.initials: G
authors.lastname: Carter
authors.forename: A
authors.initials: A
authors.lastname: Hynd
authors.forename: A
authors.initials: A
authors.lastname: Romo-Díez
authors.forename: L
authors.initials: L
authors.lastname: de Torres Espuny
authors.forename: F
authors.initials: F
authors.lastname: Royo Pla
mesh_terms: D008954:Models, Biological; D018515:Plant Leaves / Q000033:anatomy & histology / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil