The above ground plant size and form express how plants compete for space and light, and how they balance the form for, for example, water transport and transpiration, leaf display and stability, and reproduction (Sterck 2005). When size/form are considered for different ages or reference sizes, they can show major size and form changes during plant life (Poorter et al. 2007). Size and form traits are also critical for estimating the biomass accumulation and the carbon reserves in vegetations, particularly in forests (Chaves et al. 2005).