Rio Grande overbanking, Albuquerque, April 22, 2023. By John Fleck
In the early 1990s, a group of New Mexico scientists set up experimental plots at the Bosque del Apache National Wildlife Refuge on the Rio Grande south of Albuquerque for in an effort to determine what might happen when water was reintroduced to the flood-starved woods flanking the river. Their description of what happened is a delight:
The forest floor at the leading edge of the floodwaters came alive with hopping crickets and running spiders.
Molles Jr, Manuel C., et al. “Managed flooding for riparian ecosystem restoration: Managed flooding reorganizes riparian forest ecosystems along the middle Rio Grande in New Mexico.” BioScience 48.9 (1998): 749-756.
From time immemorial, this must have been a near-annual event, as the crickets and spiders scurried ahead of rising water each spring as the Rio Grande spread across the valley floor – bad for people trying to live here, great for the flora and fauna. From the same group of authors:
Extensive valley flooding would have occurred when heavy spring rains accompanied rapid snowpack melting. Whatever social disruption these floods may have caused, they would also have recharged the floodplain’s water table, saturated newly formed seedbeds, allowed fish access to nutrients released by flooded detritus on the forest flood, and accelerated nutrient fluxes in the bosque soil.
Crawford, Clifford S., Lisa M. Ellis, and Manuel C. Jr. Molles. “The Middle Rio Grande Bosque: An Endangered Ecosystem.” New Mexico Journal of Science 36 (November 1996): 276–99.
This changed in the early 1930s, dramatically, in an ecological instant as the newly formed Middle Rio Grande Conservancy District dug drainage ditches on either side of the Rio Grande and across the valley floor, throwing up the excavated dirt in spoil bank levees flanking the river’s then-main channel.
We understand what happened next thanks to a University of New Mexico biology student named Marjorie Van Cleave, who for her 1935 masters thesis documented the change. In that historic moment, plants and animals dependent on the wetlands spread across the valley floor disappeared.
As the water table was lowered three to ten feet with the construction of the Conservancy drains the swamps and lake disappeared almost immediately, leaving bare areas with water tables at various levels where succession advanced and is still advancing rapidly.
Van Cleave, Marjorie. “Vegetative changes in the Middle Rio Grande conservancy district.” (1935).
Cattails – gone. Sedges, with deeper roots, hung on for a bit longer before fading into the ecological mists. Cocklebur, Russian thistle, lamb’s quarters, sunflowers, and pigweed colonized the old marshlands of the valley floor. We are forever in Van Cleave’s debt.
What we’re seeing this spring on the fringes of the Rio Grande bears so little resemblance to the valley-wide ecosystem that it seems cheap to even compare, but the careful work of Cliff Crawford, Manual Molles, and their colleagues three decades ago trying to address this question – What would happen if we reintroduced just a bit of flooding to the forests on the river’s edges? – nevertheless draws a critical connection between the Rio Grande and the community that surrounds it.
For our forthcoming book Ribbons of Green, Bob Berrens and I are interested in that critical moment in the 1930s when, with levees and drains, the valley floor around Albuquerque was disconnected from the river. The ecology was changed, suddenly, as was the connection between human communities and their river.
From my Sept. 8, 2010 obituary of Cliff Crawford, in the Albuquerque Journal
Much of our modern understanding of the bosque ecosystem is built on the work of Crawford and Molles, who started taking students down to the river in the 1980s. For much of the time between Van Cleave’s exhaustive work and the return of Crawford, Molles, and their students in the 1980s, little scientific attention seems to have been paid to the riverside ecosystem.
I can’t find the newspaper story I wrote based on a visit to the bosque with Cliff Crawford and his then-grad student and now my good friend Mary Harner. But I did find the obituary I wrote when Cliff died in 2010.
It’s a model in my mind for public-facing science, and I’ve been thinking about it a lot as Bob and I wrestle with how to explain, in our book, Albuquerque’s modern relationship with the Rio Grande.
Mary has done an amazing job with her Witnessing Watersheds project of thinking about and documenting Albuquerque’s historic relationship with the river, and the time I have spent with her – mostly walking in the bosque, some to think of it – has been a huge influence on how I think about and approach this question.
Given flood control flow constraints, it’s hard to to get enough water through town to rise up out of the main channel and get back into the woods these days, to get it to “come alive with hopping crickets and running spiders,” but with 2023’s big snowpack, but there enough low spots providing delightful exceptions, and we’re already starting to see it rising up into those. Lissa and I were on a bosque trail near downtown Saturday when we were stopped by the water you see in the picture at the top of the blog.
There’s a sciency thing going on here – nutrient cycling, clearing out all the dry crud built up on the forest floor that in a more “natural” system would be wetted most years. (It was, in fact, Mary Harner who turned me on to the Molles et al paper I quoted above, with the hopping crickets and running spiders, when I asked for help running down the nutrient cycling piece. It turns out to be super nerdy and I probably won’t put it in the book.)
But it’s the cultural piece that I’m more interested in – the way we as a community have shifted from a desire in the 1930s to fence ourselves off from the river completely, to embracing overbanking with delight.
As often happens with these little mini-essays – sketches, really, for the book – this didn’t end up where I expected. I started with the intention of writing about nutrient cycling – printouts of research papers scattered across my desk, underlined bits, an excessive number of browser tabs.
But I realize that this is, in fact, a story about the relationship between a community and its river.