ABSTRACT Background: Bamboo species have a high potential to produce biomass and stock carbon. However, biometric tools are not available to estimate biomass production for most giant bamboo taxa. The aim was to develop an additive equation system to estimate the aboveground biomass by structural component and the total of the three bamboo species. Destructive sampling was applied, and a sample of 101 mature bamboo specimens was collected. The nonlinear power allometric model was used to integrate two additive equations systems, which were formed by the structural components of biomass: culm, branches and leaves as well as aboveground biomass total. The predictor variables were: diameter at breast height (D) for the S1 system, and D in combination with the total height (D2H) for the S2 system. Results: It was determined that the SUR method in combination with the dummy variables technique and the correction of heteroscedasticity is an adequate fit strategy. Given that the additivity property is fulfilled, specific values of the parameters of each system and by taxon are identified. In addition, the variance of the error stabilizes. The aboveground biomass of the culm constitutes 86.40%, 90.48%, and 93.94% for Bambusa oldhamii Munro, Guadua aculeata Rupr., and Guadua angustifolia Kunth, respectively. The S1 system was selected, and its statistics regarding the total aboveground biomass were 0.92, 4.9 kg, -0.35 kg, and 0.05 for the fit statistics R 2 adj , RMSE, S, and E, respectively. Conclusion: This biometric tool will easier to carry out aboveground biomass inventories, as well as to infer the carbon content and CO2 equivalent at the specimen level. Background However taxa applied 10 collected systems (D S D2H DH H (D2H Results strategy fulfilled identified addition stabilizes 8640 86 40 86.40% 9048 90 48 90.48% 9394 93 94 93.94 Munro Rupr Rupr. Kunth respectively selected 092 0 92 0.92 49 4 9 4. kg 0.35 035 35 -0.3 005 05 0.0 RMSE E Conclusion inventories CO level 1 864 8 86.40 904 90.48 939 93.9 09 0.9 0.3 03 3 -0. 00 0. 86.4 90.4 93. -0 86. 90. -

Abstract The total height (Th) of bamboo culms is essential for inventories of volume, biomass, carbon stores, and products distribution. The high density of the canopy and the natural inclination of the upper part of the crown make its direct measurement of the field difficult. Allometric equations are a viable alternative to efficiently estimating the height as a function of the diameter at breast height (Dbh). The aim was to fit mathematical models Th-Dbh and select the best predictive capacity to estimate the Th of culms of Bambusa oldhamii Munro, Guadua aculeata Rupr. and Guadua angustifolia Kunth in the Northeastern Sierra of Puebla, Mexico. In the analysis, 101 pairs of Th-Dbh observations measured in 2019 were used, with which six allometric models and three growth models were fitted by non-linear regression. Nonlinear ordinary least squares techniques with indicator variables (NL-OLS-VI) and nonlinear mixed effects models (NL-MEM) were compared. The “nlme” package of the R software was used. We evaluated the models based on the adjusted coefficient of determination (R2 ad j ), the root mean square error (RMSE), and the mean bias (B). NL-OLS-VI explained 83.5% and NL-MEM 83.2% of the observed variability. The model with the best performance was the Logistic fitted with NL-OLS-VI (R2 ad j = 0.835, RMSE = 2.280 m y B = 0.005 m). The generated Th-Dbh model is workable to estimate the Th for culms of the three bamboo taxa with low errors.

Resumen La altura total (At) de los culmos de bambú es fundamental para realizar inventarios de volumen, biomasa, almacenes de carbono y distribución de productos. Su medición directa en campo se dificulta por la alta densidad del dosel y la inclinación natural de la parte alta de la copa. Las ecuaciones alométricas son una alternativa viable para estimar eficientemente la altura en función del diámetro normal (Dn). El objetivo fue ajustar modelos matemáticos At-Dn y seleccionar el de mejor capacidad predictiva para estimar la At de culmos de Bambusa oldhamii Munro, Guadua aculeata Rupr. y Guadua angustifolia Kunth en la Sierra Nororiental de Puebla, México. En el análisis se utilizaron 101 pares de observaciones At-Dn medidas en 2019 con los que se ajustaron por regresión no lineal seis modelos alométricos y tres de crecimiento. Se compararon las técnicas de mínimos cuadrados ordinarios no lineales con variables indicadoras (MCO-NL-VI) y modelos de efectos mixtos no lineales (MEM-NL), se usó la librería “nlme” del programa R. Los modelos se evaluaron con base en el coeficiente de determinación ajustado (R2 adj ), la raíz del error medio cuadrático (REMC) y el sesgo promedio (S). MCO-NL-VI explicó el 83.5% y MEM-NL el 83.2% de la variabilidad observada. El modelo con el mejor desempeño fue el Logístico ajustado con MCO-NL-VI (R2 adj = 0.835, REMC = 2.280 m y S = 0.005 m). El modelo At-Dn generado es factible para estimar la At para culmos de los tres taxones de bambú con errores bajos.

Resumen El contenido de humedad de los culmos de bambú recién cosechados es de alrededor de 100 %, el cual se considera alto, por lo que debe reducirse mediante algún proceso de secado. Un paso clave en el procesamiento de los culmos es el secado, que ha sido poco valorado por los productores y usuarios de bambú. La exposición al aire libre es el método más utilizado en México, pero poco eficiente, ya que tarda desde semanas hasta varios meses en función de las condiciones ambientales. El objetivo del presente estudio fue evaluar el secado de secciones de culmos (6 m de longitud) de Guadua aculeata en un secador solar tipo túnel, con forma de prisma rectangular. El contenido de humedad inicial promedio fue de 106.72 %, en 80 días se alcanzó un contenido de humedad final promedio de 29.84 %. La tasa de secado fue superior a 1.0 % por día durante los primeros 20 días, lapso en el cual redujeron aproximadamente 40 % de su contenido de humedad. En los siguientes 60 días, perdieron en promedio 37.41 % de humedad a una tasa de secado variable para cada culmo muestra. La curva de secado del método evaluado corresponde a una función exponencial. Bajo las condiciones experimentales de secado se determinó que las secciones de culmos de 6 m de longitud y diámetro promedio de 12.42 cm, pueden alcanzar un CH promedio menor a 18 % en un tiempo de 109 días, para posteriormente usarse como elementos estructurales.

Abstract The moisture content of freshly harvested bamboo culms is high, near 100 %, and it should be reduced by some drying process. A key step in the processing of culms, which has been under-appreciated by bamboo producers and users, is drying. Outdoor exposure is the most widely used drying method in Mexico; however, it is not very efficient, as it takes weeks to several months, depending on the environmental conditions. The objective of the present study was to evaluate the drying of Guadua aculeata culm sections (6 m long) in a solar tunnel dryer with a rectangular prism shape. The initial average moisture content was 106.72 %, and after a period of 80 days, a final average moisture content of 29.84 % was reached. The drying rate was above 1.0 % per day in the first 20 days, during which their moisture content was reduced by approximately 40 %. In the following 60 days, they lost on average 37.41 % of moisture, at a variable drying rate for each sample culm. The drying curve of the assessed method corresponds to an exponential function. Under the experimental drying conditions, it was determined that 6 m long sections of culms with an average diameter of 12.42 cm can reach an average MC below 18 % in 109 days, thus becoming suitable for use as structural elements.