3.3. Leaf dry-matter content

Leaf dry-matter content (LDMC) is the oven-dry mass (mg) of a leaf, divided by its water-saturated fresh mass (g), expressed in mg g–1. Using these units, LWC is simply 1000-LDMC. LDMC is related to the average density (fresh mass per fresh volume) of the leaf tissues. In laminar leaves, it is related to SLA by a formal relationship involving Lth and the average density of the leaf (ρF), as follows: LDMC = 1/(ρF × SLA × Lth). Assuming that the fresh mass per volume of leaves is close to 1 g cm–3, the equation simplifies to LDMC ≈ 1/(SLA × Lth). LDMC, therefore, tends to be inversely related to SLA and Lth. LDMC has been shown to correlate negatively with potential RGR and positively with leaf lifespan; however, the strengths of these relationships are usually weaker than those involving SLA. Litter derived from leaves with high LDMC also tends to decompose more slowly than that from leaves with low LDMC. Leaves with high LDMC tend to be relatively tough (see Section 3.7), and are thus assumed to be more resistant to physical hazards (e.g. herbivory, wind, hail) than are leaves with low LDMC. Some aspects of leaf water relations and flammability (see Section 2.12) also depend on LDMC. Commonly, but not always, species with low LDMC tend to be associated with productive, often highly disturbed environments. In cases where SLA is difficult to measure (see Section 3.1), LDMC may give more meaningful results, although the two traits may not capture the same functions (this is particularly obvious in some groups; e.g. succulents have slow growth, low SLA and low LDMC; see also Section 3.1).

What and how to collect?

Follow exactly the same procedure as for Section 3.1. In many cases, the same leaves will be used for the determination of both SLA and LDMC. As is the case for SLA, LDMC may vary substantially during the day.

Storing and processing

Similarly as for SLA, except that any dry storage should be avoided (however, see the case of xerophytic species in Section 3.1), and that full rehydration before measurement is compulsory.

Measuring

Following the rehydration procedure, the leaves are cut from the stem and gently blotted dry with tissue paper to remove any surface water before measuring water-saturated fresh mass. Each leaf sample is then dried in an oven (see Section 3.1), and its dry mass subsequently determined.

Special cases or extras

Most comments for SLA also apply to LDMC.

References on theory, significance and large datasets: Eliáš (1985); Witkowski and Lamont (1991); Garnier and Laurent (1994); Hodgson et al. (1999, 2011); Wilson et al. (1999); Garnier et al. (2001a); Niinemets (2001); Vile et al. (2005); Kazakou et al. (2009); Poorter et al. (2009).

More on methods: Wilson et al. (1999); Garnier et al. (2001b); Vendramini et al. (2002); Vaieretti et al. (2007); Ryser et al. (2008).