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

For bamboo species, models for predicting culm height from diameter are not often used (Fu 2001; Watanabe
and Oohata 1980). For guadua, a simple model has been used to predict culm length (L) from the perimeter at
breast height (C), including a constant (K), which has been determined empirically (Arbelaez 1996, Cruz 1994).
For volume, some studies have related it with biomass estimation (Reid et al. 2004) or with physical and
mechanical properties of culms (Jamaludin et al. 2000)
Camargo (2006) estimated the relationship between culm diameter, culm length and culm volume by using
linear and non-linear regressions. These models were used in regression analyses of culm length, apparent and
net culm volumes being the dependent variables. The equations developed for tree mensuration are useful for
predicting total culm length and culm volume using a number of independent variables. These models can be
used with an adequate precision for estimating both variables. For estimating culm length the modified model of
Cox, which includes the stand variable square mean diameter was the best. (R 2 adj=0.49, RMSE=2.5). For
apparent culm volume the allometric model was the best among the models tested (R 2 adj=0.89, RMSE=0.005). A
linear regression model was also fitted to estimate net culm volume from apparent culm volume (R 2 adj = 0.94,
RMSE = 0.001).
With reference to stand variables, Camargo (2006) and Morales (2004) have defined that the most representative
stand variable for gathering in guadua inventories is the total number of culms per hectare. This variable defines
the potential productivity of the guadua stands and also is the base to determine harvest. Other variables as basal
area and total volume moreover could provide important information on guadua stands. However harvest plans,
traditionally have been defined with regard to number of culms to be harvested (Camargo et al. 2008; Camargo
2006).
Studies on plot design conducted within guadua stands permit to conclude that circular plots provide the highest
precision in inventories (Rijal 2006). However, plots with this shape are highly demand of sample effort and
cost of inventory could increase. In this sense, rectangular and square plots can be more easily established.
Among both plots, the rectangular have showed the lowest standard error and consequently the highest
precision. However, plots should be arranged with the longer side against the slope. In relation to plot size, Rijal
(2006) suggest that plots between 50 m 2 y 200 m 2 have the best precision. These results are also consistent with
Camargo (2006) and Schumacher (2006) who tested the precision of different plot sizes within natural guadua
stands.
Silviculture of natural guadua stands
Traditionally within natural guadua stands most of the practices are associated to the harvest. These practices are
focused in improving the access to stand and include pruning (elimination of lateral branches which are usually
thorny) and removal of those culms which have reached the last stage of maturity and during the inventories are
found dry, broken or dead. These culms are removed especially within stands with high culms density (over
6000 culms per ha). Only in few cases fertilisation is done. It is due to fact that there is scarce information on
benefits of this practice and because of productivity of stands even without fertilisation is adequate, in terms of
the amount of culms demanded in the market.
VIII World Bamboo Congress Proceedings Vol 4-38