Seeing Change
I first hiked up through the Finger Rock Canyon drainage to Mt. Kimball outside of Tucson, AZ in 1981 and immediately fell in love with the trail. Starting in saguaro and palo verde desert, the trail climbs over 4,150 feet into ponderosa pine forest. After a few hikes, I decided to learn as much as I could about the area, and by 1984 I was recording all of the plant species I saw in flower, as well as vertebrate species (birds, mammals, reptiles, and amphibians) I observed. My primary focus is upon plants, but early on I found that looking for vertebrates by scanning the surrounding area, as well as looking at one or more individuals, helps me find more plants and flowers. I have now made 1,366 hikes up to Mt. Kimball and have amassed well over 206,000 observations of 601 plant taxa and 218 vertebrates.
The most salient characteristic of the data I have collected is the incredible variability I observe from year to year. As seen in figure 1, every year is different from all others. I’ve been frequently asked if spring was early this year or if it is a particularly good spring. I have to respond, “That depends” and “It’s too early to tell.” The spring flowering season began earlier for some species this year—indeed I saw the first “spring” flowers in November last year—and later for others. Initially there was not a lot of species diversity, but as weeks passed, I began to see more and more different species in flower. At this point in time I would consider diversity at least normal and perhaps a little higher than usual. For some species the flowering season seems prolonged, and for some it has been quite short. Some species are abundant and others are represented by only one or very few individuals. What I have found over the years is that it is easier to make assessments of what is happening on the ground when looking back at the end of a season. By collecting analyzable data, you can arrive at much more reliable conclusions, and that, I think, is why the data I collect are important.
All the variability—year to year, season to season, within the elevation gradient, and within and between species—makes it difficult to see long-term trends or changes. Hiking the trail about once a week, I do develop impressions of what is occurring on the ground, but it is difficult to know for sure if I am seeing what I think I am seeing. Are some species moving upslope? Is the flowering season getting shorter for some plants? Is biodiversity decreasing? Are the changes I am seeing in vegetation due to drought or to climate change or both? To answer such questions, statistical analysis of the data is essential, and I have been very fortunate to be able to work with both an ecologist and a meteorologist to analyze my data. Now I can say the data show some species are moving upslope, the flowering season for some species is getting shorter but for others it is getting longer, and diversity seems to be decreasing at lower elevations but increasing at upper elevations. As far as the drought/climate change question, we might have a better idea in another thirty years or so.
My effort is used by the USA National Phenology Network (USA-NPN), located in Tucson, as an example of the value of systematic data collection by amateur (as opposed to professional) scientists. In two follow up blogs, Theresa Crimmins (Partnerships and Outreach Coordinator at the USA-NPN) and Echo Surina (USA-NPN Communications Specialist) will delve deeper into how the Network uses partcipants’ data and how you can participate, as well as changes we might expect to see in the future.