"7:30 sharp. I'll be there," I replied.
The next morning Shana, Rob, and Matt rolled up in "the Beast," a name the Great Sand Dunes' rangers affectionately call an old, camouflaged, ex-army Chevy 4x4 that they loan to visiting researchers. We piled into the Beast and headed out onto the sand sheet.
Shana, Rob, and Matt are visiting researchers from Montana State University who are surveying exotic species in areas that have yet to be mapped. Besides the Chevy, their equipment is quite simple: aerial photographs, GPS units (which serve also as handheld computers), and a species key for the plants of the area. All this fits into small backpacks along with water and a bit of food for the day.
The bright morning sun was still casting long shadows from the rabbitbrush and chico as we worked our way northward. (Chico is the local name for a spiny relative of spinach, otherwise called Sarcobatus vermiculatus or greasewood.) We drove through a number of gates on the Medano Ranch toward our sandy survey locations, which are about five miles west of the main dunefield.
Shana expected to find exotic plant species in areas that would have a bit of standing water during at least part of the year. In those areas, exotic plants would have better success surviving on the sand sheet, which receives less than 10 inches of precipitation per year. On the aerial photographs, the darker areas potentially represent locations with the most vegetation. We would be searching through a number of those vegetated oases today and our first stop was a series of grassy wetlands called Elk Springs, located right on the boundary of the park.
Shana explained clearly that this was a survey, not an inventory. Researchers must be much more meticulous when they are inventorying. In an inventory, all species within a set of parameters are identified and counted, such as a complete inventory of beetles at Great Sand Dunes National Park and Preserve. In contrast, a survey will sample an area for specific sets of data. In this case, Shana and her team were looking for exotic plants, but they expected to only find a few species, mostly Russian thistle (tumbleweed) and Canada thistle. They were mapping Canada thistle, but since Russian thistle was just about everywhere, they had decided not to map this exotic plant.
August is a glorious time of the year to visit the sand sheet around Great Sand Dunes. The native flowers are in full bloom and hummingbirds are getting their final fill of nectar before heading south to Central America for the winter. It is hard not to be pulled temporarily away from the task at hand when the beauty is so overwhelming.
We walked until we reached the western edge of the grasslands near Elk Springs and decided to move on to the next survey location. While Shana and Matt finished entering data into their GPS units, Rob walked back to get the truck and picked us all up. We were off to our next destination.
On the aerial map, a series of parabolic dunes were shown to contain dark areas—a clue for exotic plant potential. We drove as close as possible to the site and began the sandy hike through the dunes and into the interdunal, grassy meadows. A few of these vegetation 'islands' were composed completely of native vegetation and others had exotic species. Why some were infested and others were not, no one could say. Shana pointed out that whether they found exotics or not, the survey would help park managers in the future: they could compare new surveys with her team's data to see if the Canada thistle had spread or if additional exotics had arrived.
Like a public service announcement on television, an ounce of prevention is worth a pound of cure, Shana noted that "early detection means prevention." Prevention is the easiest and most cost-effective method for managing invasive plants. If we discover early which exotics are invading and where they are heading, we might have the ability to stop them before they spread too far. Unlike Russian thistle, which seems to be here for good, there may be newcomers that can be nipped in the bud.
We took a break around noon underneath some narrow-leaf cottonwoods, had a snack, and filled up on water. The arid air of the San Luis Valley can sure take the moisture away from one's body. It's hard to imagine how these plants survive with the little water they receive—water that trickles quickly down through the soft, permeable sand.
Matt was on his first year with Shana's crew and helped me to understand that at least one good thing comes from exotic species. They help to bridge the gap between communities of people. Exotic species are not only invading National Parks and Wilderness areas, but they are also competing for space in agricultural and ranching areas. Since sometimes these groups of people have differing views on issues, exotic species is one issue that unites each of their interests. Even I have found a reason to dislike Russian thistle: in the late summer, the leafy barbs are in some ways sharper (or at least more annoying) than the spiny pads of native prickly pear cactus.
Our surveys continued through the afternoon heat and ended at a large grassland on the western edge of our aerial photograph. Shana, Rob, and Matt spread out and wound their way through the grassland finding little cause for concern. They found only one small patch of Canada thistle in the entire area.
When they dropped me off at home that afternoon and we had said our good-byes, only half the work was done. The data must be downloaded, edited, and final maps created. This takes a bit of work behind the computer. From the sound of their voices, it seemed like they all enjoyed being out in the field more than doing the required office tasks. I couldn't blame them. But the finishing work must be done so future researchers can use their data to help manage and protect the natural plant communities of Great Sand Dunes National Park and Preserve.