Allometry, Growth and Survival of Three Eucalyptus Species (Eucalyptus benthamii Maiden and Cambage, E. dunnii Maiden and E. grandis Hill ex Maiden) in High-Density Plantations in Uruguay

Abstract

This study presents a yield model for aboveground biomass production from three species the Eucalyptus in northern and western regions of Uruguay, based on sampling records from intensive crop plantations. High-density eucalyptus plantations represent a forestry alternative for the production of forest biomass. This work assessed the survival and growth of three eucalyptus species (Eucalyptus benthamii Maiden & Cambage, E. dunnii Maiden and E. grandis Hill ex Maiden) planted at densities of 2220, 3330, 4440 and 6660 trees ha−1, for a period of 57 months in northern (Tacuarembó) and western (Paysandú) regions of Uruguay. Linear and logarithmic equations of individual volume were fitted by site and species. The survival of E. grandis, E. benthamii and E. dunnii was not related to planting density, and the highest mortality values occurred in Tacuarembó. The effects of competition among trees were more evident at the highest planting density for E. grandis. In all species, the reduction in diameter was more marked than that of height, as planting density increased. Tree volume showed the same trend, and this was higher with higher planting densities. At Tacuarembó, the volume was the highest with E. benthamii at 6660 trees ha−1 (416.4 m3 ha−1), and, at Paysandú, the highest production was obtained with E. grandis (370.7 m3 ha−1) and with the densities of 4440 and 6660 trees ha−1 (305.9 and 315.3 m3 ha−1, respectively). With all species and planting densities, there was an increase in the accumulated volume during the 57-month study period; however, growth curves indicate that the maximum production per unit time and, therefore, the optimum harvest time occurred at 48 months. In this work, it has been shown that the use of intensive short-rotation plantations of eucalyptus for the production of biomass in Uruguay is suitable in soils prioritized for forestry.

Survival and initial growth in the field of eucalyptus seedlings produced in different substrates

“…Seedling size is important for predicting the success of a plantation because it is directly related to the plant's capacity to overcome weed competition and develop new roots (Khanal et al, 2018;Riikonen & Luoranen, 2018). It should be noted that, compared with diameter, height seems to be much more dependent on environmental factors, such as weed competition and plant density (Resquin et al, 2018).…”

“…In general, nursery managementincluding substrates, irrigation, and nutrition -affects directly seedling morphological characteristics, which may result in different responses in the first months of the plantations. Besides seedling size, other factors, such as genetic potential, plant density, climatic conditions, and soil characteristics, may also interfere in plant survival and initial growth after planting (Resquin et al, 2018;Shalizi et al, 2019).…”

Stand biomass estimation methods for Eucalyptus grandis and Eucalyptus dunnii in Uruguay

“…Models for all components and systems were fitted using the same procedure, which accounted for biological correlation between components. Several growth and yield model systems have been proposed for these species, although few allometric biomass equations are available for eucalypt plantations (Resquin et al 2018).…”

“…Biomass additivity is a desirable characteristic of a system of equations for predicting tree component and total tree biomass. Most biomass equations reported in literature are not additive and were developed separately for each biomass component (Lin et al 2017, Resquin et al 2018. The biomass additivity approach has been used by some researchers in the fitting of biomass equations (e.g.…”

“…In Uruguay, several growth models have been developed for Eucalyptus globulus Labill, Eucalyptus grandis W. Hill ex Maiden, Eucalyptus dunnii Maiden and Pinus taeda L., for both solid wood and cellulose production (Rachid-Casnati et al 2014, Resquin et al 2018. It is necessary to adjust systems for Uruguayan plantations, to avoid the use of allometric models from elsewhere or based on unsuitable ranges of predictive variables, which can lead to over-or underestimation of AGB.…”