Thursday, September 3, 2015

Fire, transpiration, local hydrology and some very happy sunflowers

The Rocky fire swept through McLaughlin Reserve at the end of July. Nearly five weeks later, I resurveyed some sites that I went through the week after. The amount of life that had survived in the completely wrecked sites was astonishing, as was the quick resprouting of some plants (Rhamnus, Salix, Quercus, Vicia, Brassica, Asclepias, etc.). But the most surprising thing was the "winners" of the fire. I've walked columbine this seep many times a week during the past two summers. This time, I was struck by how large several serpentine sunflowers (Helianthus exilis) and tumbling orache (Atriplex rosea) had become.

Several stupendously super-sized serpentine sunflowers stoutly standing in foreground. A couple orache visible in the background.
Before the fire and all of last year, these were quite small plants, reaching maybe 1-2' tall with a couple dozen flowers. In many places, they end at 6-10" with just a few flowers. These plants were over 3' tall and each had a hundred or more flowers. What happened?

Last year there was a little bit of odd late-summer weather, with a few overcast cooler days (it is usually above 90 and not a cloud in the sky here). On those days, one very small seep that I had a columbine population in would fill up a couple tiny puddles that hadn't had water for months. After a couple times, I mentioned this to the reserve manager here and she pointed out that the plants around the seep don't transpire as much on cloudy days, so the water being put out by the seep was not being used up before it got to the ground. 

What transpires less than plants in overcast conditions? Dead plants. Right after the Rocky Fire, the seep with the sunflowers was flowing again big time (it is much larger and had much denser vegetation around it than the one that I could see the changes before). The amount of water in this seep now is greater than it's been since April or so. While the sunflowers and Atriplex are past the end of the visible water in the seep by a few dozen yards, it is still flowing belowground and these are pretty much the first plants that would be getting any of that water, as all plants upstream are fried.  

This section had been completely dry for months before the plants stopped sucking up all of the water flow. Also note all the greenery. That is resprouting of Aquilegia eximia, Stachys albens, Salix sp. and a few grasses and sedges (you can fire me as your naturalist if you'd like - I have no idea what species are here).  
This was an cool and unexpected - though completely logical - thing to find in the aftermath of the fire. I'm sure its been described before, but it was really eye-opening to me to see how much water those plants were transpiring and just how much influence this had on the hydrology and the success of other plants far below them (it seems like asymmetric resource competition - the manzanita and willows above were dictating the reproductive potential of the sunflowers below).

Something similar may have been happening to trigger this flowering of Mimulus guttatus, but I'm a bit puzzled, as this was in a strange location for that to occur and nothing else around it was doing particularly well. It was certainly a pleasant surprise to see some spring-like color at the end of the summer!
I'll write a longer post about the Jerusalem fire (more lost experiments... but not all!) and some other interesting observations that I've had during my last couple days of wanderings. But I've got more field work to do now. 

Dragonflies were hanging out in the seep like nothing had changed. I believe this is Aeshna walkeri (common last year here and with the same gestalt), though I didn't have my net with me to confirm and I wouldn't have wanted to disturb her egg-laying anyway (I'm a bleeding heart when it comes to dragonflies... and snakes... and beetles... and others). 


2 comments:

  1. Hi Eric:

    Time ago visiting your blog, but had not had the opportunity to comment on your observations.
    What to tell? I'm working as a park-ranger in a National Reserve (or protected wildlife area). In the place where I work we had a fire that affected about 5,000 hectares, in a mountain valley called "Las Águilas". The most affected, unfortunately, was adult native forest, followed by open scrub. However, much of high Andean vegetation was also burned, where you find an abundance of coironales (Festuca sp or Stipa sp, "you can fire me as your naturalist if you'd like - I have no idea what species are here").

    In other similar fires here, coironal regeneration is observed within a few days the fire ravaged (~ 7 days). In fact, these valleys have a story about farming-“cordillerana" (called "Veranadas", equivalent to “verano” or summer) where the “arrieros” (Chilean cowboy) raise their cows to graze "up in the mountains" (https://www.youtube. com / watch? v = DKmjztK4mYk). And before the winter, when all their animals down, lit fires across the valley (thousands of hectares) for another summer had a beautiful coironal for their animals again.

    I have not had the opportunity to go see the affected area of "Las Águilas" now, but I hope many surprises in October or November when to enter (it's now something icy and snowy).

    Here's an approximate coordinate fire:

    37 ° 1'2.78 "S - 71 ° 17'27.48" O

    Regarding the native forest, I do not expect much to do. Perhaps reforestation, but the costs are very high and priorities go the other way (Also, is it necessary to reforest?). What interests me a lot, are the other herbs I hope that already in November, especially a number of species that are used as "herbal", example:
    Ñancolahuen (Valeriana carnosa)
    Doradilla (Cheilanthes glauca)
    Paramela (Adesmia emarginata), If you add the “mate” is spectacular.
    Mimulus also hope to observe, although before the fire managed to find very, very few (2 species: Mimmulus glabatus and Mimmulus cupreus, ¿low abundance? or i'm getting blind).

    Told you when i have some news.

    Well “che”, congratulations on your work. Every time I read your blog, I remember that I studied biology (Keep in mind that I took a year in administrative jobs... falling into depression).

    I hope you are well. Hugs.

    PD: I tried to post some pictures, but i have no idea how to put it on the blog (!)

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    1. Link: https://www.youtube.com/watch?v=nVeazbZ_dm8

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