Subalpine mixed conifer US-Vcm

Subalpine mixed conifer US-Vcm

Location	35.888447, -106.532114
Elevation	3000 m
Dominant Vegetation	Before burn: Abies concolor, Pseudotsuga menziesii, Picea pungens, Populus tremuloides After burn: Sambuca racemosa, Populus tremuloides
Mean Annual Precipitation	646 mm
Mean Annual Temperature	6.4 C
Ameriflux link for data and info	http://ameriflux.lbl.gov/sites/siteinfo/US-Vcm
Phenocam images	phenocam.nau.edu/webcam/sites/vallesburnedconifer/

Left to right: Subalpine conifer site from 2007-late May 2013; Aerial photo of tower site 2 weeks after the stand replacing burn in June 2013; Subalpine conifer site June 2014; Subalpine conifer site July 2016, dominant vegetation is now elderberry and aspen seedlings, 1-2 m in height.

Overview of data from 2007-Nov 2022 from US-Vcm

Top panel: Monthly net ecosystem exchange of carbon (NEE, net carbon balance where positive values indicate net carbon release to the atmosphere and negative values indicate net carbon stored in the ecosystem). Second from top: Monthly sums of Gross Primary Production (GPP, total carbon entering ecosystem through photosynthesis) and Ecosystem Respiration (RE, total carbon released through both autotrophic and heterotrophic respiration). Third from top: Monthly sums of Evapotranspiration (ET, total water released to atmosphere through transpiration and evapotranspiration) and incoming solar radiation (Rg). Bottom panel: Monthly precipitation totals (Precip) and average air temperature (bottom). The Thompson Ridge fire burned through this site starting in late June, 2013.

History of site

This tower was set up by the NSF Science and Technology Center for the Sustainability of Semi-arid Hydrology (SAHRA) in 2005 in the ~1200 km2 Jemez River basin of the Jemez Mountains in north-central New Mexico at the southern margin of the Rocky Mountain ecoregion in the Valles Caldera National Preserve. The overall effort was geared toward understanding the role of vegetation type and structure on basin scale water resources. When SAHRA ended, University of Arizona secured additional funding for this site through 2018 through the Jemez-Santa Catalina Critical Zone Observatory. My lab has been collaborating with SAHRA and CZO and running this tower, with partial support from these sources, since October 2006. Additional funding for this site has come from NASA-ROSES (2010-2013), and current funding for this tower is through Ameriflux Management Project, which started in 2013.

This site experienced a very hot, stand-replacing burn in late May/early June 2013. We were able to access the site for an hour a couple of days before the burn and removed the most expensive instruments, but still lost instrumentation and a lot of infrastructure at this site. With support from the Ameriflux Management Project, we reinstrumented this site in Nov 2013, and were able to install a new tower on the west side of the Valles Caldera in an unburned subalpine mixed conifer site, instrumented using one of AMP's Rapid Response Systems for 3 years.