Spatial stochastic modeling of resin yield from pine stands

The spatial structure of resin-yield in maritime pine stands in central Spain was studied on two different scales and with data from two tapping periods (1998 and 1999). For the fine scale, Moranʹs I and the K function were used to study within-stand spatial variation. We found that in one plot, trees separated by distances of less than 5 m had similar production. The K function results showed that the distribution of trees did not depart significantly from complete spatial randomness. For a much larger scale, data was available from 37 and 59 ten-tree plots for years 1998 and 1999, respectively. Partial (monthly) yields were also measured. The experimental variograms for the mean plot production showed that a large percentage of the total variance was spatially structured. Furthermore, the experimental variograms for the partial yields revealed changes in the spatial structure of this phenomenon within the same year. Spatial stochastic modeling was shown to be an effective and economic modeling strategy. Temporal variation should be included in future work, with the use of geostatistical space-time models.