Shoot allometry ofJatropha curcas

Abstract

The South African government has banned planting of Jatropha curcas L. (Jatropha), potentially a multipurpose tree and biofuel source, owing to insufficient knowledge about the species. Use of allometry as a non-destructive method of monitoring growth and biomass attributes of Jatropha was investigated. The objectives were to examine: reliability of allometry between above-ground variables and basal diameter and crown depth of Jatropha; effects of below-ground interspecies competition and tree spacing on allometry; and validity of these relationships with independent data. The study site was Ukulinga Research Farm, South Africa. Destructive sampling was carried out in March 2008, and tree height and basal diameter were measured periodically during March 2005 to April 2007. Regression analysis and analyses of covariance were used to analyse the data. The height-diameter equation developed by destructive sampling was validated using independent data. Highly significant allometric regressions resulted from using basal diameter (r ≥ 0.89) and crown depth (r ≥ 0.94). Stem diameter had linear relationships with wood and foliage biomass percentages (r = 0.91). Height-diameter equations were equivalent across competition and tree spacing treatments. Predicted and measured tree heights were linearly related (r > 0.97). It could be concluded that above-ground allometry of Jatropha was very reliable and not significantly affected by either below-ground interspecies competition or tree spacing. The site-specific allometric equations are useful for accurate and non-destructive estimations of Jatropha growth under various growing and (non-pruning) tree management conditions. The equations presented here are, however, not universally applicable.

Tree or shrub: a functional branch analysis of Jatropha curcas L.

“…The taproot biomass and diameter data were log-transformed prior to regression analysis using least trimmed squares (LTS) to account for heteroscedasticity and potential outliers in the data. Predicted outputs were back-transformed and verified with a correction factor (Ghezehei et al 2009). Statistical analysis used SAS 9.3 (SAS Institute Inc., Cary, NC, USA).…”

“…Achten et al (2010) developed empirical allometric equations (d) Fig. 3 Comparison of predicted and measured aboveground tree biomass components: a measured total biomass, b measured branch biomass, c measured twig and leaf biomass and for belowground d measured total proximal root biomass using stem diameter to estimate aboveground biomass based on data obtained from 41 jatropha seedlings (up to 3 cm stem diameter), while Ghezehei et al (2009) used stem base diameter and other predictors to develop allometric equations for aboveground biomass estimation using 12 samples aged 16-24-monthold. Makungwa et al (2013) developed two aboveground biomass allometric equations based on stem diameter measured at 10 cm aboveground from 172 and 442 samples of one to three-year-old jatropha planted as smallholder crop boundary hedges, in five different regions.…”

“…Jatropha allometric research historically used empirical models and destructive sampling to determine aboveground biomass (Ghezehei et al 2009;Achten et al 2010;Makungwa et al 2013), with limited belowground data (Firdaus and Husni 2012;Baumert and Khamzina 2015). However, there are no data available for biomass partitioning in the generative stage (harvest index).…”

Equações Alométricas para Estimativa de Fitomassa em Cultivo de Pinhão Manso

“…Após a avaliação da significância estatística, a equação foi comparada com outras três equações desenvolvidas para obtenção de estimativas da fitomassa do pinhão manso para os cultivos entre 3 e 4 anos de idade (Toledo et al, 2012;Ghezehei et al, 2009). …”

“…Essas estimativas são facilitadas ao assumir-se que a fitomassa se constitui em um componente dependente de variáveis dendrométricas de fácil mensuração no dossel, tais como altura e projeções da copa, combinadas ou não (Ghezehei et al, 2009;Rolim et al, 2006). Cole & Ewel (2006) alertam para a dificuldade de se encontrar relações alométricas para árvores do gênero Jatropha, devido ao fato de que muitos dos modelos desenvolvidos ainda se baseiam no volume do dossel (Miranda et al, 2011), enquanto que o crescimento do pinhão manso se dá de forma modular em progressão geométrica, surgindo dois ramos a partir de cada inflorescência, assim sucessivamente (Dias et al, 2007).…”