Precipitation partition in a tropical montane pine-oak forest in central Mexico

Abstract

Precipitation partitioning is a key process in the terrestrial phase of the water cycle since it regulates the amount of water available for other processes. Precipitation partitioning in throughfall, stemflow and interception loss was measured on a daily basis in a tropical pine-oak forest at 2,160 m elevation in the Cuitzeo watershed, located in central Mexico for 26 months. The recorded precipitation of 2,882 mm (Aug.28/2010 - Oct.23/2013) included 242 events; 35.5 % of rainfall events were < 5 mm and only 16.1 % exceeded 20 mm. Throughfall (TF), stemflow (SF) and interception loss (E_t) corresponded to 80.6 %, 2.4 % and 17.2 % of gross precipitation (P_g), respectively. Free TF component (p) was 0.86 mm mm^-1 and canopy storage capacity (S) 0.29 mm. Trunk storage capacity (S_t) averaged 0.023 mm and mean stemflow proportion (p) was 0.0055 mm mm^-1. SF index averaged 0.411 L mm^-1 per tree while mean trunk capacity volume was 1.43 L. E. correlated negatively with P_g while TF correlated positively with P_g. Empirical models that describe SF index (as volume) and trunk capacity volume as functions of tree height, tree diameter at breast height and projected crown surface were successfully fitted.