Trees, Forests and People (Sep 2023)
Drought occurrence and forest management: Interrelated drivers of sanitary logging in central México temperate forests
Abstract
Drought exacerbates forest pest outbreaks, causing widespread tree mortality. In México, to control bark beetle outbreaks, mandatory sanitary logging is carried out by the landowners who can use or sell the resulting wood. We analyzed the temporal trend of reported bark beetle outbreaks and their relationship to drought conditions; and assessed the intensity of the sanitary logging in relation to land tenure type and the pre-existing Forest Management Program (FMP) as a proxy to determine whether sanitary logging is being used only for its primary purpose: bark beetle population control. We used official records of bark beetle outbreaks (n = 11,151) on four major conifer species (Abies religiosa, Pinus hartwegii, P. pseudostrobus, and P. oocarpa) that triggered sanitary logging authorizations (n = 1,968) between 2009 and 2021 in two highly affected states: Michoacán and Estado de México. Results showed that reported bark beetle outbreaks increased from an average of 38 in 2009 to 1,051 in 2021, and were associated with droughts that occurred up to two years earlier. More severe droughts were recorded in Estado de México, but more sanitary logging authorizations were issued in Michoacán (829 and 1,139, respectively). In Michoacán, the area logged was smaller, but the sanitary logging was more intensive (2,623 ha, x̅ 139 m3/ha of wood extracted) compared to Estado de México (9,227 ha, x̅ 38 m3/ha of wood extracted). These sanitary logging interventions occurred equally on communal and private lands, but from 58% (Michoacán) to 69% (Estado de México) occurred on properties without a pre-existing FMP. While the results suggest that in some areas, particularly in Michoacán, sanitary logging may serve as a legal pass to harvest timber, further research is needed on ecological and social issues, such as: forest characteristics that may influence beetle reproduction and dispersal, local pest management practices, forest governance and conflicts, and the effectiveness of technical assistance and monitoring to control outbreaks, among others.
