Every morning I walk down to the river’s edge to watch the sunrise. In late April the sky and trees are buzzing with hummingbirds, the mournful cooing of white winged doves, and the trilling of red winged blackbirds. As I wait for that pinpoint of light to blossom into a golden orb I look to the gnarled trunks of cottonwood trees (Populus delitoides wislizenii) that stand out against a background of blue slate marveling at the shapes, size, and trunk texture of such magnificent rapidly growing shade trees, trees that I have come to love so much, now drooping with male and female russet catkins (each on separate trees). I think about the heart shaped leaves that will soon grace bare branches rustling in the slightest breeze and the birds and small animals that will find safety under the massive canopies of these (egalitarian) Matriarchs of the Bosque. And I think about their future…
The Rio Grande Bosque is a system of wetlands, oxbow lakes, sandbars and woodlands that supports the growth of cottonwoods and willows, one of the most critically endangered habitats in the world. Seasonal flooding once cleared debris and enriched the soil allowing new seedlings to germinate, but over the last century large scale agriculture, irrigation systems, livestock grazing and logging have created soil erosion and extremes in flooding. Dams were built to control floods and wetlands were drained.
Mature cottonwoods have roots that can reach down to the water table, but young cottonwoods cannot germinate or grow unless they have enough water available to them near the surface.
The cottonwoods I love are “elders” but young cottonwoods are scarce or completely absent except in a few locations near the river (my friend Iren’s Bosque is a small but healthy ecosystem that is flourishing with the next generation of cottonwoods but this riparian area still floods in the spring). Whenever I gaze up or sit under one of these magnificent trees that are dressed in such golden splendor in the fall, I wonder how many people are aware of the fact that these gracious matriarchs will disappear from the landscape within less than a century even without assistance from climate change.
This year severe drought has added another layer of distress to an already critical cottonwood situation. All trees have access to food through their complex underground root systems and their relationship with certain fungi but trees cannot deal with ongoing thirst.
Groundbreaking scientific tree/plant research indicates that when trees are threatened with lack of water, food production and growth cease. The trees that suffer the most are the ones like cottonwoods that grow in soils where moisture is most abundant. Deeply distressed thirsty trees send vibrations through their trunks when the flow of water from the roots to the leaves is interrupted. These vibrations could be understood as cries of thirst, a sobering thought for anyone who loves cottonwood trees (or any tree for that matter) and sees them as sentient beings as I certainly do.