This field campaign offered us the opportunity to obtain data on shrub and tree canopy heights that will help to characterize lidar measurements from NASA's Laser Vegetation Imaging Sensor (LVIS), an advanced prototype instrument that collects waveforms, rather than discrete lidar returns. Our work was performed in the beautiful landscape and unique ecosystem of the Chihuahuan Desert grasslands and in the Gila National Forest, New Mexico. Our desert grassland work was accomplished in -- and with a lot of help from -- the USDA, Agricultural Research Service Jornada Experimental Range (with special thanks to Al Rango, Connie Maxwell, and Amy Slaughter). A comparative analysis of the acquired ground reference and the lidar data will determine the accuracy and limit of the full waveform lidar in measuring the height of the low biomass canopies. We'll also use very high resolution imagery from the JER's unmanned aerial vehicle to map shrubs at the field sites precisely and to estimate their heights, allowing us to scale up to the 20 m LVIS footprint size. More here.

So, why all this effort? There are various dimensions to assessing the possibility of rapid climate change from changes in the carbon cycle. We are most concerned with increases in Earth's temperature, often coined "global warming", although "climate disruption" might be better because although the planet as whole is retaining more energy, the effects will be unevenly distributed. Depending on how weather systems are disrupted regionally, these effects may include higher or lower surface temperatures and increased or decreased precipitation. Vegetation and community responses to higher atmospheric CO2 and associated changes, and the amount of carbon stored in biomass raise some of the most important questions in global ecology and climate change, and in particular how these changes will feed back to the atmosphere, back to terrestrial ecosystems, back to the atmosphere, back to terrestrial ecosystems, back to the atmosphere, back to terrestrial ecosystems.... and so on. In short, we need to know where the carbon is, including carbon in arid and semi-arid woody plants (there's often more carbon in the soils but this tends to be a relatively stable pool -- for now).

The data collected during the campaign will allow scientists to assess the accuracy and sensitivity (lower limit) of the lidar measurements on woody canopies, which could have implications for estimating the amount of carbon in aboveground woody biomass: we need to quantify the uncertainties in our remote sensing measurements. You may think that dry region shrubs and trees don't really store that much carbon compared with, say, tropical or boreal forests. This is absolutely true on a unit area basis -- but drylands are very extensive globally, so their contribution should not be ignored.

After the campaign one of the graduate student partipants, Rejina Sharma, wrote: "While carrying out the field work, I noticed that the dominant plant species in the desert grassland was primarily honey mesquite (Prosopis glandulosa), an invasive species. The encroachment of problematic species affects community composition and patterns of ecosystem interactions, impacting native species populations. This shows the necessity of addressing these transitions and has implications for preserving the incredible grandeur of the southwestern wilderness."

Notable event: a swarm of (Africanized?) bees came our way at the mesquite site and a mad dash for the 4x4 ensued. There was a panic moment worthy of Hitchcock as we rushed back to the 4x4 only to find the electric window cracked and the keys hiding some place obscure. We managed to avoid any confrontations with rattlesnakes, mountain lion, tarantula wasps, black widow spiders, scorpions, and bears.

P.S. Congratulations to our alumna Gina Mongiello who just obtained a position with the Essex County Environmental Center in Roseland!