The authors acknowledge that the result when they looked at the effect of piñon die-off from the Four Corners drought a decade ago seems counterintuitive:
Basins with the most tree die-off showed a significant decrease in streamflow over several years following die-off, and this decrease was not attributable to climate variability alone. The results are counterintuitive compared to responses to reductions in tree cover by harvest that have shown an increase in streamflow, although such increases are more substantial for locations with higher precipitation than where the piñon pine die-off occurred.
That’s Maria-Teresa Guardiola-Claramonte and colleagues in Journal of Hydrology last year. They looked at a number of basins along the Colorado-New Mexico border, along with controls elsewhere that did not suffer piñon die-off, and found consistent reductions in runoff coefficients (watershed runoff as a fraction of basin precipitation).
Anyone know of other work on this question?