Crown condition of Mexican forests: Analysis 2014

Data analysis of the health indicator crown condition is presented for the data collected in 2014 by the National Forest and Soils Inventory (NFSI); it included 88 162 trees localized in 1443 plots. The analyzed variables were: Live crown ratio (Lcr), Crown density (Cden), Foliage transparency (Ftra), and Crown dieback (Cdie). Descriptive statistics were obtained for each one, for all the trees, by group (conifers and hardwoods), and by genus. Tree health was categorized based on thresholds proposed in previous studies. The average values for Lcr, Cden, Ftra, Cdie for all the trees were 35.9%, 44.4%, 50.6% and 2.6%, respectively, meanwhile for hardwoods 32.7%, 44.2%, 50.5% and 2.7% were the reciprocal, and in conifers they were 47.5%, 46.2%, 51.1% and 1.2%. Averages for 18 genera with n >= 1000 were obtained. Regarding health, more than 50% of the trees showed Lcr in the poor category, 27.9% in the same category for Cden, 60.26% with severe Ftra and less than 1%, severe Cdie. 54.2% of the hardwoods showed poor Lcr, and 67% of the conifers severe Ftra. Nayarit and Jalisco states presented the lowest quality of tree crowns. It is a priority to generate our tree crown standards, to train field crews, and perform measurements in the right season. This is the first analysis of crown condition health indicator for Mexican forests, a joint effort of the NFSI and the Forest Health Department of the National Forestry Commission.