Why don't our stands grow even faster? Control of production and carbon cycling in eucalypt plantations

Transpiration along an age series of Eucalyptus globulus plantations in southeastern Australia

“…Similar trends have been measured in Eucalyptus saligna and Eucalyptus laevopinea forests (Cornish and Vertessy, 2001) and studies in other genera have shown that stand transpiration peaks around the time of maximum growth rates and stand leaf area before declining with age (Kö stner et al, 2002;Delzon and Loustau, 2005). These same trends are likely to occur in Eucalyptus plantations, where peaks in current annual increments and LAI often occur before age 15 years and in some cases as early as age 2 or 3 years (Florence, 1996;Almeida et al, 2007;du Toit, 2008;Ryan et al, 2008). The objective of this study was to determine (i) if stand transpiration declined with age after reaching an early peak, (ii) if this decline is associated with a decline in leaf area index and current annual growth rates, and (iii) how water use efficiency (stand biomass or volume production per unit water transpired) changes with time?…”

The role of canopy structural complexity in wood net primary production of a maturing northern deciduous forest

“…In our study, canopy structural complexity was greater in plots with higher site quality, regardless of stand age. In higherquality sites, trees allocate more to aboveground biomass production, accelerating stand structural development (Litton et al 2007, Ryan et al 2008. In spite of varying rates of change in canopy structural complexity, we observed a clear increase in rugosity with age, underscoring the convenience of age as a proxy, but emphasizing how little understanding of underlying mechanisms it provides.…”

Growth and physiological responses to silviculture for producing solid-wood products from Eucalyptus plantations: An Australian perspective

“…In a study of E. nitens and E. globulus, Moroni et al (2003) demonstrated that root length density and root frequency were greater on droughtsimulated soils compared to those under irrigation. Changes in biomass allocation to favour above-ground growth at the expense of below-ground growth has been observed following fertiliser application and irrigation (Giardina et al, 2003;Ryan et al, 2008;Stape et al, 2008). While this increases volume production, it may also increase drought susceptibility and reduce stand stability.…”