A Dendro-Spatial Analysis in Tree Growth Provides Insights into Forest Productivity

Climatic disturbance is an increasingly important factor that modifies forest structure and species composition. These modifications strongly affect competition among trees, size and distribution variability, growth and mortality. This leads to declining stocks with serious implications in the provision of various ecosystem services, particularly in natural protected forests. This study combines dendroecological data for interpreting the spatial variability existing in growth of Picea chihuahuana, Abies durangensis and Cupressus lusitanica of northern Mexico along a period of 54 years (from 1960 to 2014). The research was carried out through a retrospective analysis of ring width and basal area increment (BAI) using Moran’s I index. We tested whether tree growth responses were spatially autocorrelated and used this as a proxy to evaluate if BAI values are declining under adverse climatic conditions. Such conditions may be affected by temperature, evaporation and drought. The results revealed non-random growth patterns in all three species, with high competition in terms of BAI. The values of BAI showed some variations in productivity with two opposing trends in Picea chihuahuana and Abies durangensis. Both species exhibited signs of a decline attributable, presumably, to drought, while Cupressus lusitanica was less sensitive to this factor. Spatial autocorrelation analysis, along with dendrochronological data, represents a valuable tool to study the productivity of forests.