WBC-VIII-Vol.4 – Resources – Forestry, Plantations and ... - BambuSC

aboveground and belowground competition results in decreasing annual rates of biomass gain. Control of
standing-culm density is the most important measure to combat such a decline in productivity.
In order to be sustainable, outputs from production must be at least matched by inputs, and provision of those
inputs must not jeopardise the sustainability of the resource pool from which the inputs are drawn.
Four major examples may be cited. Firstly, the pool of carbon dioxide which provides the chemical basis for
much of biomass (on average c. 50% by dry weight of biomass is carbon – Scurlock et al. 2000) is to all intents
and purposes limitless, and unlikely to diminish because of the photosynthetic demand by bamboo. Within the
canopy on still days carbon dioxide may drop to a concentration that does limit photosynthesis, but that is
another story. Secondly, the fresh water resource available to bamboo globally is sufficient to satisfy the demand
by 40 Mha of bamboo, but locally this may not be so. Spatial heterogeneity in the distribution of water
resources for bamboo, whether it simply be rainfall or captured and stored water resources, will influence the
biomass production of bamboo, and the choice of plantation set-ups. Inordinate demand on stored water
reserves to the detriment of that water use by other industries, especially if the total resources are depleted over
time, cannot be considered as sustainable. Practices to increase the efficiency of producing shoots or culms per
unit of water uptake and to optimise the use of the water resources should be implemented.
Thirdly, the spatial heterogeneity of mineral nutrients contained with the soil likewise strongly influences
bamboo biomass production, and, if not replenished as they are removed in harvested shoots and culms, can
limit the sustainability of bamboo stands. As a final example, the availability of labour or mechanical practices
that satisfy the high demands for either by the bamboo crop will constrain the sustainability of bamboo
production. Excessive costs for mechanical solutions to harvesting and processing of bamboo products, or
competition with alternative livelihoods for the normally surplus labour pool, can limit the sustainability of
bamboo production. These need to be considered when planning for expansion of the industry. On the positive
side, establishment of new bamboo plantations and their intensive management open up new job opportunities
and scope for economic growth, regionally and nationally.
In order to address the sustainability of bamboo production, from an input-output perspective, it is necessary
firstly to consider potential yield and output data, and then to relate that to known resource availabilities and to
resource use efficiency by bamboo stands in the face of varying input availabilities.
Expected bamboo yields
Bamboo is best known for its fast growth rate. It can produce harvestable culms within 4–7 years of planting,
which subsequently can be harvested annually. For this reason, it is expected that in the future, the major
demand for bamboo will be for timber substitution more than for edible shoots. Recognising this potential, in
recent years, there has been increasing documentation of bamboo productivity (Isagi 1994; Isagi et al. 1997;
Kleinhenz and Midmore 2001; Hunter and Wu 2002; Wang 2004; Castaneda-Mendoza et al. 2005; Midmore
2009a).
Focusing on the above-ground culm biomass, but excluding data for branches and leaves (and data that appear
erroneous), the above-ground culm weight of the highest-yielding bamboo stands (c. 150 t/ha) is similar to that
VIII World Bamboo Congress Proceedings Vol 4-70