The use of multiple return data might have made the characterization of such variation across the study sites feasible, since many of the variables included in the model were based on the number of returns, instead of using the number of pulses. A group of models explaining between 61% and 83% of the LAI variation was reported. The reason for this range is the number of variables in each model. Although the most parsimonious model is generally considered best, this applies to cases when the stability
of the model can be compromised or when the estimation of an additional variable impact on the research or operation costs, check details which is usually the case in biological sciences (Rawlings et al., 2001). Adding a lidar metric to the model will not increase the cost in a significant matter, since the highest cost is the acquisition of the lidar data itself. It will only add computational time, therefore a 6-variable model (with stable regression estimates) for predicting LAI can only increase the accuracy of the predictions. The decision of which model should be used will depend on a forest manager’s needs. If a good approximation of the estimates and relative
variation of LAI values is sufficient, the 2-variable model will be appropriate, but if higher accuracy is wanted, a 6-variable model will be the best choice. LAI is a useful index for intensive plantation management because it provides an estimate of the amount of light captured by this website the stand and is thus a proxy variable that defines the stand’s find more current growing conditions. For instance, LAI allows foresters to identify stands that are in need of fertilization (e.g., when LAI is low) or thinning (e.g., when LAI is high), in order to improve tree growth and maximize returns. The 6-variable model, with an RMSE for prediction (CV-RMSE) of 0.46, provides a precise tool for this type of management, in which decisions are usually made based on LAI thresholds. In this case, an error
of this magnitude in estimating LAI for forest management purposes is not as important as the consistency of the estimated values across stands under different conditions (the ability to use the same model across different stand ages, fertilization regimes, vegetation controls, etc.). For forest managers, the advantage of having a model that estimates LAI using remotely sensed data resides in the accuracy and robustness of such models. Although satellite-derived LAI estimates rely on models with R2 values similar to those of the lidar model developed in this research ( Flores et al., 2006), such estimates have not been consistent, mainly due to issues associated with sensor saturation, atmospheric conditions, and the inability to account for the vertical structure of the stand ( Peduzzi et al., 2010).