Vegetation moisture content can be expressed in two quantities, first is Fuel Moisture Content (FMC) and second is Equivalent water thickness (EWT). FMC is calculated as ratio of difference between fresh and dry leaf weights and the fresh weight. It is expressed as percentage or weight units like g/g of fresh weight. EWT is the ratio of difference between fresh and dry leaf weight and leaf area. It is expressed as g m-2 of leaf area. The leaves are dried at 70o for 48 hours.
Measuring FMC and EWT are simple procedures, however have to be carried out with careful consideration. For instance, measuring fresh leaf weight and leaf area as soon as they are plucked form plants is essential. Leaves need to be kept in sealed plastic bags and kept cool to avoid water loss.
Measuring leaf area can be very tricky especially when leaves are narrow or of irregular shapes and thickness. Instruments such as Leaf area meter are used by researchers to estimate leaf area. However digital photographs of fresh leaves can also be used for leaf area measurements with the help of software such as ImageJ.