Diesel Trees - Bioenergy Crop Plants - page 624

of 0.13 L during the first tapping and 0.16 L during the second tapping. Plowden (2003) studied
Copaifera oleoresin production from three different species in Pará, Brazil on the Alto Rio Guamá
Indigenous Reserve. Trees 55 to 65 cm DBH yielded the most oleoresin, averaging 459 mL after
two holes were drilled.
Some of the highest recorded average yields per tree were seen in the southwestern Brazilian
Amazon in C. reticulata and C. paupera trees with 2.92 and 1.33 L, respectively (Rigamonte-
Azevedo et al. 2006). However, these numbers were averages among oleoresin-producing individuals
only. Only 27% of C. reticulata trees and 80% of C. paupera trees produced oleoresin. It is not clear
whether the lack of uniformity in oleoresin production stems from tapping methodology or whether
the oleoresin itself is just not produced constitutively in all trees. Significant variation, both natural
and in response to herbivory, in chemical composition of C. langsdorfii, leaves has been noted
(Macedo and Langenheim 1989a, c). This variation, compounded by variation in climate, nutrient
availability, and other factors, could also cause sporadic oleoresin production and therefore explain
the variation seen in oleoresin collection.
Multiple harvests have also been considered to increase oleoresin yields. Cascon and Gilbert
(2000) tapped 300-550 mL of oleoresin from a single C. duckei tree ten consecutive times
at 4-month intervals, but they never depleted the tree of oleoresin at any point. However, it is
impossible to determine how much oleoresin collected at each interval was residual material that
had been stored in the tree and how much had been synthesized and replaced between tappings.
Most studies suggest that primary tapping accesses oleoresin from accumulations in heartwood
that have built up over long periods of time (Plowden 2004) and therefore would not quickly
regenerate for a secondary major harvest as Calvin had originally hoped. The density of trees also
ranges from 0.1 to 2.0 per hectare depending on location and forest type (Rigamonte-Azevedo
et al. 2004).
It is unknown how phenology plays a roll in oleoresin production. As mentioned before, the
chemical composition of the Copaifera oleoresins changes throughout the year, but no specific
cause has been identified as the factor driving this change. Phenology studies of Copaifera species
are rare and focus more on the flowering, seed set, and leafing patterns (Pedroni et al. 2002). Most
of these types of studies have been in C. langsdorfii, , a species native to the southern parts of Brazil.
However, oleoresin collection for commercial products occurs more commonly in the northern half
of Brazil and South America. From our experience, the species C. multijuga and C. reticulata are
most commonly available for purchase outside of Brazil, although they are often mislabeled as
C. officinalis. .
In a recent visit to Brazil during July, we were able to observe the oleoresin collection process
(Figure 24.1). The trees had to be drilled by hand, and reaching the core of the tree to access
the heartwood where the oleoresins are stored was not easy. We observed the tapping of 12 C.
langsdorfii trees, none of which produced oleoresin. It was suggested that these trees may not
produce oleoresin at all, or that they may not be in season because July is during the winter or dry
season. This again reinforces the notion that tree species native to the northern parts of Brazil are
more suitable for production of oleoresin, or at least traditionally there is a more widespread culture
of oleoresin collection in the north.
24.6 comParInG oleoresIn to dIesel Fuel
Diesel fuel, like gasoline, consists of many different compounds isolated from only one fraction of
the greater mixture known as crude oil. Diesel fuel distills from crude oil between the temperatures
of 200 and 350°C. Not all diesel fuels come directly from primary distillation; processes such as
catalytic cracking, which breaks larger, denser molecules into smaller ones, have been developed to
generate more liquid fuels from crude oil barrels (Bacha et al. 2007). In general, diesel fuel is made
up of paraffins (alkanes), naphthenes (cycloalkanes), olefins (alkenes), and aromatics. As mentioned
before, Copaifera oleoresins consist primarily of sesquiterpenes hydrocarbons.