Evaluación del análisis dimensional para estimar biomasa forrajera y utilización de damiana (Turnera diffusa Wild.) por bovinos en Baja California Sur, México

Abstract

The objective of this research was to evaluate the Dimensional Analysis Method to estimate biomass production of the damiana (Turnera diffusa Wild.) and its utilization by cattle in Baja California Sur, Mexico. Seven independent variables (dimensional measures) were used to predict 4 dependent variables (biomass evaluating the linear models (Y = a+bXj. multiplicative (Y = aX^b). exponential (Y exp(a+bX) and logaritmic (Y = a+blnX). The results of the Simple Regression Analysis show that the model with better adjustment for the estimate of biomass in the area with no use was the multiplicative, being for BT and Bh the associated variables the DCM with r2 of 0.5346 and 0.5330 and CAM with 0.3907 and 0.3923 with values of EEE of 0.46; while for the Br and Bt associated with the variable DBM and CBM with r2 of 0.4357; 0.4357 and 0.51 65; 0.5562 respectively and with values for EEE of 0.53. For the grazing area the best model was the logarithmic one with the same variable, though with smaller coefficients of determi nation. The variable height turned out to be the worst predictor variable for all the models. There fore the Multiple Regression Analysis showed more important improvements in terms of coefficient determination and EEE than the Simple Regression Model. The models show ing a better adjustment for all biomass (BT. Br. Bt and Bh both in the area without and with grazing were the multiplicative and exponential ones, with coefficients of determination of 0.9935.0.9648; 0.9649, 0.9505: 0.9904, 0.9546; 0.9650. 0.8114, respec tively; and values of EEE that go from 0.00 to 0.14 for associating variable combinations: DBM. DCM. CBM. CAM, Area and Volume. Generally, with the elimination of the intercept to the equation line, were obtained better coefficients of determination. The utili zation results in terms of the evaluated dependent variables show that, in average, the BT of the plant was used in 32.78 % while with respect to Bt Br and Bh the utilization was of 32.08. 11.82 and 60.49 %. Concerning the independent variables the utilization in base to height was of 45.70 % while with respect to DBM, DCM. CBM and CAM the utilization experienced values of 7.50, 37.42, 1 5.80 and 58.32 %. The utilization in base to Area and Volume presented the greater values with 61.78 and 73.63 %. It may be concluded that the Dimensional Analysis permitted to estimate biomass and utilization of the damiana from dimensional measures in a fast and reliable way with the use of multiplicative and exponential multiple models better than from simple models. Fi nally, in those areas where the conditions to determine production and utilization impose limitations for the use of other traditional methodologies, it is possible to use the Dimensional Analysis Method with good results, namely in communities of shrubs that present character istics similar to those evaluated in this study.