Tree growth response to drought of co-occurring Pinus spp. in the Sierra Tarahumara, México

POMPA-GARCÍA, M; HADAD M.

Mendoza

Conferencia; Third American Dendrochronology Conference; 2016

Tree Ring Society

The Sierra Tarahumara in northern Mexico is home to diverseindigenous ethnic groups that are heavily dependent on forestry.Two species of ecological and industrial interest, Pinusdurangensis and P. lumholtzii, grow in this ecosystem. Althoughdrought-induced tree mortality has recently receivedconsiderable attention, the dendrochronological potential ofthese two Pinus species has not been explored. We evaluatedgrowth responses of P. durangensis and P. lumholtzii to droughtusing tree-ring chronologies for the years 1900-2012. Thechronologies were correlated with the StandardizedPrecipitation-Evapotranspiration Index (SPEI) to determine thetime scale over which drought significantly affected tree growth.Comparison of correlation coefficients revealed that P.durangensis is more sensitive to drought than P. lumholtzii. Treeradial growth of P. durangensis from January to October wassignificantly and negatively affected (r = -0.19 to -0.34) bydrought during the previous growth period; in contrast, P.lumholtzii showed more drought resistance, with only growthfrom January to February significantly and negatively affected(r=-0.17 to -0.19) by drought during the previous growth period.Dry conditions before tree-ring formation affect radial growth inboth P. durangensis and P. lumholtzii. Our results suggest thatthe increased frequency and severity of drought predicted forthis region in coming decades will impact forest productivity andcarbon cycles.