Application of a process‐based model for predicting the productivity of Eucalyptus nitens bioenergy plantations in Spain

Abstract

The feasibility of using plantation-grown biomass to fuel bioenergy plants is in part dependent on the ability to predict the capacity of surrounding forests to maintain a sustainable supply. In this study, the potential productivity of Eucalyptus nitens (Deane and Maiden) Maiden plantations grown for bioenergy in a region of north-west Spain was quantified using the 3-PG process-based model. The model was calibrated using detailed measurements from five permanent sample plots and validated using data from thirty-five additional permanent sample plots; both sets represented the variability of climate and soils of the region. Plot scale analysis showed that the model was able to reasonably estimate above-ground biomass and water use when compared with the observed data. Using a representative loam soil characteristic, a spatial analysis was then carried out to predict the potential productivity of E. nitens for bioenergy across a potential area for plantation establishment of 2550 km 2 and to evaluate different management scenarios related to rotation length and stocking. An increase of only 1.9% in mean annual increment (MAI) of above-ground biomass (W AGB ) was found between stockings of 3000 and 5000 trees ha À1 ; for the lower stocking, MAI of W AGB increased 4% for rotation lengths between 6 and 8 years. Production was reduced by low summer rainfall and to a lesser extent by high summer and low winter temperatures, and vapour pressure deficit. Above-ground biomass production was higher by around 12% when average rather than actual climate data were applied. The information from this study can be used to optimize forest management, determine regional relative potential productivity and contribute to decision-making for bioenergy production from E. nitens plantations in north-west Spain.

ABOVEGROUND BIOMASS GROWTH AND YIELD OF FIRST ROTATION CUTTING CYCLE OF Acacia AND Eucalyptus SHORT ROTATION DENDROENERGY CROPS

“…In this study, at 7,500 trees ha -1 E. camaldulensis and E. nitens showed the highest average yield (22.5 and 35.2 Mg ha -1 ) 48 months after the establishment of the trials. In turn, (González-García et al, 2016a) reported an annual production of only 13.7 Mg ha -1 (lower than that found herein) seven years after establishing the plantation. According to Sochacki et al (2007), E. globulus plantations at 4,000 trees ha -1 accumulated 16.6 Mg ha -1 of dry material after the plantation's third year.…”

Dynamic growth and yield model including environmental factors for Eucalyptus nitens (Deane & Maiden) Maiden short rotation woody crops in Northwest Spain

“…The inclusion of these parameters confirms the fact that E. nitens growth is affected by climate factors in summer: Although annual total precipitation in the area is approximately 1,250 mm, well within the requirements for the species, which have been established as between 750 and 1,750 mm year -1 (FAO 1981;Booth and Pryor 1991), rainfall in the study area is in fact considerably reduced in summer, which can affect tree growth, as has been shown in another study on the same permanent sample plots (González- García et al 2015). Moreover, higher summer temperatures increase tree evapotranspiration, which together with the reduction in soil water content, means that growth is likely to be negatively affected in this season.…”

Quantifying the effects of Eucalyptus plantations and management on water resources at plot and catchment scales

“…Predictions of plantation growth at plot scale using 3‐PG are useful, and species‐specific growth parameters are required, as has been shown in other studies of eucalypt plantations in Brazil and other countries (Stape et al, ; Almeida et al, , ; Fontes et al, ; Almeida and Sands, ). Spatial applications also have been used elsewhere (Coops and Waring, ; Tickle et al, ; Almeida et al, ; González‐García et al, ), and the model is used for research and operations by some forest plantation companies (Almeida et al, ; Almeida et al, ). However, 3‐PG integration with a hydrological model (TOPMODEL) allows predictions of water balance at catchment scale that can take account of different land‐use and management options.…”