This article is modified from Perez-Harguindeguy et al (2013). The “New handbook for standardised measurement of plant functional traits worldwide” is a product of and is hosted by Nucleo Diversus (with additional Spanish translation). For more on this and on its context as part of the entire trait handbook visit its primary site Nucleo DiverSus at http://www.nucleodiversus.org/?lang=en
The area of a leaf (also called leaf area, LA) is the most common metric for leaf size and is defined as the one-sided or projected area of an individual leaf, expressed in mm2 (see Specific leaf area). Interspecific variation in LA has been variously related to climatic variation, geology, altitude and latitude, where heat stress, cold stress, drought stress, nutrient stress and high-radiation stress all tend to select for relatively small leaves. Within climatic zones, variation in the LA may also be linked to allometric factors (plant size, twig size, anatomy and architecture, leaf number, number of lateral buds produced) and ecological strategy with respect to environmental nutrient stress and disturbances, and phylogenetic factors can also play an important role.
Units, terms, definitions
LA – leaf area (units: mm2 ; range of values: 1 – >206)
SLA – specific leaf area: the one-sided area of a fresh leaf, divided by its oven-dry mass (units: mm2 mg-1 or m2 kg-1; range of values: <1-300)
What and how to collect
For the leaf-collecting protocol, see under Specific leaf area that LA is rather variable within plants and we recommend collecting a large number of replicates (i.e. close to the higher end of the number of replicates recommended in Table 1 of Selection of species and replicates for functional trait analysis). For storing leaves, see Specific leaf area.
Measure the individual leaf lamina for species with simple leaves. For compound-leaved species, either the leaflet area or the whole LA can be measured, and the appropriate decision depends on the research question at hand. For the heat balance, the leaflet area is important, which is functionally analogous to a simple leaf. When analysing total light capture, the whole leaf should be measured. Ideally, determine for compound-leaved species both the leaflet area and whole LA, because this allows one to address more questions and to compare the results with other studies. Measure the laminae with or without petiole and rachis, according to the objectives of your study (see Specific leaf area), and always report this in your publication. Note that this whole LA may be different from the area used to determine SLA.
Notes and troubleshooting tips
Special cases or extras
- Leafless plants Because leaflessness is an important functional trait, record LA as zero for leafless species (not as a missing value). However, be aware that these zeros may need to be excluded from certain data analyses. Alternatively, sample leaf analogues (see Succulent and leafless plants in Specific leaf area).
- Heterophyllous plants See Specific leaf area.
- Ferns See Specific leaf area.
- Leaf width This is measured as the maximum diameter of an imaginary circle that can be fitted anywhere within a leaf, and is an additional trait of ecological interest related to leaf size. Narrow leaves, or divided leaves with narrow lobes, tend to have a smaller boundary layer and a more effective heat loss than do broad leaves with the same area. This is considered adaptive in warm, sun-exposed environments. There is also emerging evidence that leaf width contributes more positively than does the area of the whole leaf to the expression of canopy dominance.
- Leaf number per node Leaf size is a compromise between functional and resource-use efficiency. Plants are modular in construction and, as a result, these functions can be partially uncoupled. Species with alternate, opposite and whorled leaves frequently co-exist and leaf dry mass or area multiplied by the number of leaves per node provides additionally a crude estimate of the size of each growth module. This may in extreme cases be 10 times the value of a single leaf.
References on theory, significance and large datasets:
Ackerly DD, Knight CA, Weiss SB, Barton K, Starmer KP (2002) Leaf size, specific leaf area and microhabitat distribution of chaparral woody plants: contrasting patterns in species level and community level analyses. Oecologia 130, 449-457. doi:
Cornelissen JHC, Pérez-Harguindeguy N, Díaz S, Grime JP, Marzano B, Cabido M, Vendramini F, Cerabolini B (1999) Leaf structure and defence control litter decomposition rate across species and life forms in regional floras on two continents. New Phytologist 143, 191-200. doi:10.1046/j.1469-8137.1999.00430.x
Givnish TJ (1987) Comparative studies of leaf form: assessing the relative roles of selective pressures and phylogenetic constarints. New Phytologist 106, 131-160. doi:10.1111/j.1469-8137.1987.tb04687.x
Milla R, Reich PB (2007) The scaling of leaf area and mass: the cost of light interception increases with leaf size. Proceedings. Biological Sciences 274, 2109-2115. doi:10.1098/rspb.2007.0417
Niinemets Ü, Portsmuth A, Tena D, Tobias M, Matesanz S, Valladares F (2007) Do we underestimate the importance of leaf size in plant economics Disproportional scaling of support costs within the spectrum of leaf physiognomy. Annals of Botany 100, 283-303. doi:10.1093/aob/mcm107
Niklas KJ, Cobb ED, Niinemets U, Reich PB, Sellin A, Shipley B, Wright IJ (2007) “Diminishing returns” in the scaling of functional leaf traits across and within species groups. Proceedings of the National Academy of Sciences, USA 104, 8891-8896. doi:10.1073/pnas.0701135104
Parkhurst DF, Loucks OL (1972) Optimal leaf size in relation to environment. Journal of Ecology 60, 505-537. doi:10.2307/2258359
Poorter H, Rozendaal DMA (2008) Leaf size and leaf display of thirty-eight tropical tree species. Oecologia 158, 35-46. doi:10.1007/s00442-008-1131-x
Raunkiaer C (1934) -The life forms of plants and statistical plant geography.’ Clarendon Press: Oxford, UK.
Royer DL, McElwain JC, Adams JM, Wilf P (2008) Sensitivity of leaf size and shape to climate within Acer rubrum and Quercus kelloggii. New Phytologist 179, 808-817. doi:10.1111/j.1469-8137.2008.02496.x
Westoby M, Falster D, Moles A, Vesk P, Wright I (2002) Plant ecological strategies: some leading dimensions of variation between species. Annual Review of Ecology and Systematics 33, 125-159. doi:10.1146/annurev.ecolsys.33.010802.150452
More on methods:
see references in More on methods of Specific leaf area.