Allometric Models for Estimating Carbon Fixation in Citrus Trees

Abstract

Citrus fruits play an important part in the Spanish agricultural sector. These orchards could play an important role as a terrestrial C sink and contribute to C fixation. We proposed quantifying the net primary production in different‐aged citrus trees through the measurement of annual increases in the C content of the biomass of trees of different ages completely excavated. The measured net primary production in mature citrus was 27 kg C tree–1 (1143 g C m–2 yr–1; 11.4 Mg C ha–1 yr–1) with a similar behavior to that of different forests. Moreover, in this experiment, allometric equations for the estimation of annual net primary production in citrus orchards based on the relationship between net primary production and biometric variables were established. These equations could be a useful tool to calculate the potential C fixation in citrus areas. Canopy volume was the best variable for predicting above‐ and belowground biomass. Leaf area index and trunk diameter could also be selected as reliable and easily measurable variables to estimate net primary production in the whole tree.

Deep rooting of rainfed and irrigated orange trees in Brazil

“…The tree biomass measured in our study at age 7 years was only reached at age 11 years in Spain, where trees are considered adult from age 8 years onwards. The rates of biomass accumulation were slower in the Spanish orchards sampled by Quiñones et al (2013) than in our study and only 27% of the total biomass was found belowground in 8-year-old trees (\20% from age 10 years onwards), while root biomass accounted for 35-38% of the total biomass in our Brazilian orchard.…”

“…(Raf. ), which represents [70% of the orange production in Spain (Quiñones et al 2013). The tree biomass measured in our study at age 7 years was only reached at age 11 years in Spain, where trees are considered adult from age 8 years onwards.…”

Carbon stocks and changes in biomass of Mediterranean woody crops over a six-year period in NE Spain

“…Citrus The citrus biomass dataset only comprises data from literature, from two references in particular. Quiñones et al (2013) showed aboveground and belowground biomass data from 2-to 14-year-old Navelina orange trees (Citrus sinensis L.) in Valencia (Eastern Spain), while Iglesias et al (2013) showed aboveground and belowground biomass data from 2to 14-year-old Clemenules trees (Citrus clementina Hort. ex Tan.)…”

“…In this respect, promoting carbon sequestration and storage in biomass and soils has become one of the most important mitigation measures in the fight against climate change. Therefore, reliable evaluation of C fixation in terrestrial sinks would be useful, in order to quantify their spatial and temporal variability, gain a better understanding of the carbon cycle and assist mitigation policies worldwide (Quiñones et al 2013;Huffman et al 2015). Moreover, although plants are able to capture atmospheric CO 2 , their effectiveness as a C sink depends on residence times (Quiñones et al 2013).…”

“…Almagro et al (2010) estimated both above-and belowground biomass in an olive grove of SE Spain. Two key studies on citrus have been conducted in Mediterranean regions such as Eastern Spain (Iglesias et al 2013;Quiñones et al 2013). With respect to vines, some studies have been published about carbon stocks in California (Keightley 2011;Williams et al 2011;Iglesias et al 2013) and allometries in Spain (Miranda et al 2017).…”