Tuesday, April 29, 2008

Other places, other riparian habitat

Over the last month or so, it's been irrigation ditch, canal, and acequia clean-up time over the southwest. Much of the water in AZ and NM used for agriculture comes from surface irrigation supplies, especially in NM. The supply canals, ditches, and acequias are mostly unlined, so they end up supporting a wide variety of riparian and irrigation-induced wetlands. When it is clean-up time, the vegetation gets burned and the ditches get dug out. In some areas of CO that I've visited this spring (if you could call it that a month ago), even the freshwater marsh (i.e., cattails) that inhabits some of the low-lying swales gets burned.

We use these agricultural resources, and I understand the need to have a clear-flowing ditch or acequia to supply water to pastures and food/hay crops. Unfortunately, in many areas of the southwest, the acequia-induced habitat is most of what's left of the fairly vast riparian zones along the once-perennial or strongly-intermittent stream systems with occasional tenajas to supply water throughout the year. When the riparian habitat gets burned, there's that much less during the year for southwest critters to use as forage, nesting, and refuge habitat. One could argue that the riparian veg grows back, but the temporal loss still remains.

This all reminds me of the two months one summer (before the axis of evil) spent in the mountains of a central asian country, one with a very tall volcano. Like NM, the mountain villages (and the desert communities, too) have well-developed irrigation supply systems to provide their fields with water. The systems are called qanats (covered in the desert), some which have been in place for over a thousand years (or so I was told). I wasn't there during spring qanat-cleaning, but one of the practices I saw made me shudder all the same.

I was there as a tagalong with a more official research team. I was lucky enough to be looking at Neogene fluvially-derived sediments for a independent study-type project, of which there is a fairly large wedge in the local area. There are also springs in the hillsides of these sediments which support a diverse, fairly native (as far as I could tell) riparian habitat. There is little riparian along the creeks and rivers for both natural and anthropogenic reasons (primarily because the streams run big and carry lots of coarse-to-fine grained sediment - boulders to silts/clays - that blow out streamside veg). As such, the hillside springs support riparian veg that acts as forage, nesting, and refuge for the local central asian critters including these big, honking grouse-like birds that were about small turkey-sized. Each spring-fed riparian zone would house about 2-3 of these grouse, about half an acre in size. The locals would torch the zones to drive out the grouse-y birds, which they would then shoot for sport and dinner. In the area in which I was working, I recollect about three of these zones along one large stretch of hillside. There weren't very many, over all, and they housed what was left of the native habitat (probably having been grazed/flooded out centuries ago). I still think it was a shame to destroy those, even temporally, for one or two dinners, when a whole herd of goats and sheep were there to provide cheese, yogurt, milk, and meat on a very regular basis.

My other main recollection is that, like Europe, there is no place without people. I could not go about with my head uncovered, even in the mountains, as there was always the chance of coming upon a goatherd or another local, or even one of the religious police (yes, even in the mountains). I still think how lucky I am to live and work in the southwest, where I can always escape to fairly empty places, without a headscarf.

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