If we were really paying attention, we’d notice that trees are on their way up the mountains. With increasing drought and heat, soils evaporate more moisture. Trees are gradually found in greater abundance at higher elevations. Lower ranges where trees forested the landscape are turning to grass and woody shrubs.
In Tucson, where my novel, Threshold, takes place, a long term study dramatically revealed this “march up the mountains”.
Richard Brusca and a team of scientists found the lower ranges of mountain conifers and trees had advanced up the mountain over a 60-year period. During that time they also documented a decrease in average precipitation and a 10 degree increase in average temperatures on Mt. Lemon in the Santa Catalina Mountains near Tucson.
A study conducted in the ’60s established the baseline data for a companion study using the exact same transects and protocol to count the numbers of species in the study area. This allowed scientists to compare and document changes over time.
The message? Forest communities are undergoing ecosystem change on a large scale and in a relatively short time.