Effects of Tamarisk Beetle Herbivory On Tamarix Mortality and Flower Production along the Rio Grande in New Mexico
Levi R. Jamison1* and Matthew J. Johnson2
1 EcoPlateau Research, Flagstaff, AZ, USA; levisor7@hotmail.com
2 EcoPlateau Research, Flagstaff, AZ, USA; matthew.johnson@nau.com
We studied the impact of tamarisk beetles (Diorhabda spp.) on Tamarix spp. canopy health from 2015–2018. Changes in tree health were monitored on three occasions per summer at 16 sites along the Rio Grande between Los Lunas, NM and El Paso, TX. At each site, 25 Tamarix were surveyed for tamarisk beetles with a sweep net, and the phenology of each Tamarix, and the stand, was visually estimated. We analyzed the relationship between Tamarix defoliation and Tamarix flower production, as well as trends in Tamarix canopy mortality over the time of the study. We found a negative correlation between Tamarix defoliation and flower abundance. We also found that Tamarix canopy mortality was variable across sites, with some sites exhibiting no change in canopy mortality while others having large (>50%) increases. Our results suggest that tamarisk beetle defoliation has variable effects on long-term Tamarix mortality but pertinent impacts on annual flower production of Tamarix negatively affecting recruitment of new Tamarix.