Height and diameter data for Pinus merkusii and P. michoacana in Zambia
Data presented here includes pairs of tree height and diameter collected during forest inventories in the Copperbelt province in Zambia. These data were collected from the four different plantation sites (i.e., Chati, Ichimpe, Lamba, and Ndola). We present datasets for 1,542 trees (i.e., 761 and 781 trees of P. merkusii and P. michoacana, respectively). The dataset zamemi_11.csv was used for model development and zamemi_16.csv for model validation.
Steps to reproduce
Data presented were collected during the forest inventories of 2011 and 2016 from the forest plantations in Copperbelt province in Zambia. We used the Swedish Haglöf diameter mantax blue calipers to collect diameter data, and for height, we used the Finnish Sunnto clinometers. The Garmin GPS 62s were used for locating stands and sample plots. Microsoft Excel was used for initial data processing. The R studio implemented in the R statistical software version 3.5.1 was used for data exploration and modeling. We used simple fixed effect models procedure and the mixed-effect. Before developing a simple mixed-effect model, we created an object of the groupData class with height as a function of measured diameter, allowing parameter estimates to vary with species nested in stands using the non-linear mixed effect (nlme) and the lmfor package implemented the R statistical software. In this formulation, possible hierarchies (i.e., plots to stands and stands to sites) of the data were taken into account through random effects. For the model formulation, readers are referred to the associated article at https://doi.org/10.1016/j.agrformet.2021.108510