Several studies conducted on northern hemisphere species have observed lower drought tolerance in seedlings compared to that in coppice ( Oechel and Hastings 1983, Fleck et al. globulus coppice is less well understood than seedlings, despite acknowledgement that seedlings and coppice will experience different conditions at the same site. It is also possible that microclimatic differences, including atmospheric vapour pressure deficit (VPD), will occur between coppice and seedling canopies. In addition, the disproportional amount of live below-ground biomass in coppice could mean that coppice and seedlings experience different soil moistures because of contrast in the spatial distribution of roots. Seedlings, in contrast, allocate assimilated carbon to biomass components to bring the supply of nutrients and water into balance with demand so that under resource (water or nutrient) limiting conditions, assimilated carbon will be directed to the growth of roots and away from the above-ground components ( Santantonio 1989, Battaglia and Sands 1997). Regardless of this mechanism, vigorous above-ground growth has been observed during early coppice development in E. This imbalance between above- and below-ground biomass may also mean that starch reserves and current photosynthate can be allocated to above-ground biomass components instead of roots. globulus stem is harvested, the root system is potentially able to supply large quantities of nutrients and water relative to the size of the developing shoots, because it has access to more soil resources and a large intrinsic store of carbon in the form of starch reserves ( Fleck et al. Growth form in this context describes the structural contrast between coppice and seedlings.Īfter an E.
For example, information on leaf-scale carbon gain and water use in coppice and seedlings would extend our understanding of the long-term trade-off between stand productivity and drought susceptibility in multiple rotation systems employing these growth forms. Realising the potential of these tools will therefore require a quantitative understanding of key processes that affect growth in each such system. Unfortunately, such models have not been parameterized to account for genetic differences in planting stock within species, genetic gain or for second rotation coppice and seedlings. 2004) are one of the options for simulating potential yield. Process-based models of plantation growth (e.g., CABALA – Battaglia et al. After harvest, plantation managers can choose to re-establish the plantation either with new seedlings or by allowing the cut stumps to resprout (coppice). Most of these plantations were established after 1997 and over the past 3 years the harvested area has increased exponentially. is a globally significant plantation species and more than 450,000 ha are now planted in Mediterranean environments across southern Australia ( Parsons et al. The underlying cause of this inherent difference is discussed in the context of the allocation of resources to above- and below-ground organs during early development.Įucalyptus globulus Labill. Thus, at a leaf scale, seedlings are potentially more productive per unit leaf area than coppice during early development, but this is not realised under ambient conditions. During the same period, there was no significant difference between coppice and seedlings in either their stomatal response to leaf-to-air vapour pressure difference ( D) or intrinsic water-use efficiency CO 2- and light-saturated rates of photosynthesis were greater in seedlings than that in coppice as were the quantum yield of photosynthesis and total leaf chlorophyll content. Coppice not only grew more rapidly, but also used more water and drew on stored soil water to a depth of at least 4.5 m during the first 2 years of growth, whereas the seedlings only accessed the top 0.9 m of the soil profile. globulus coppice and second-generation seedlings during their early development in the field. In this study, we compared the intrinsic (independent of the immediate environment) and native (dependent on the immediate environment) physiology of E. The capacity to predict productivity using these tools is dependent on an understanding of the physiology of seedlings and coppice in response to light, water and nutrient supply.
Currently, long-term growth data comparing coppice and seedling productivity in second or later rotations in southern Australia is limited. globulus may be established either by allowing the cut stumps to resprout (commonly referred to as coppice) or by replanting a new crop of seedlings. Eucalyptus globulus Labill., a globally significant plantation species, is grown commercially in a multiple rotation framework.
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