Zion National Park

Zion National Park:
13 to 26 August, 2016 

We sampled fire and forest history in Zion National Park in August 2016 to provide data for the Park's Fire Management Plan. What a terrific place to sample fire history! Lots of old trees and stumps, and of course a beautiful place to spend a couple of weeks. We concentrated on ponderosa pine forests in upland areas on the East Rim and Horse Pasture Plateau and Pine Valley on the West Rim. Much of the Park's prescribed fire program has been focused on these landscapes. I used similar methods as in past studies (e.g., Brown et al. 2008) in which we used an n-tree density-adapted plot design to characterize age and forest structure in randomly located plots. We also sampled remnant (only stumps and logs) fire-scarred trees wherever we could find them. Another goal for the study was to collect as much data as we could from the old stumps. Upland forests on both east and west sides of the main Canyon were heavily harvested in the late 1800s and early 1900s, and stumps are rapidly being lost as the Park is reintroducing fire back to these areas. In the following photos you can see locations where the Park has burned in the last 20 years or so. We ended up with a total of 28 plots, about 850 trees total. 

This report describes some of the vegetation structures we found, plus an overnight backpack I did on the West Rim Trail. 
 

North Fork of the Virgin River near Road Junction
 

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One of the old fire-scarred stumps we targeted for sampling.
 

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A closeup of the fire scars on the "wing" of the stump. They're often fragile but we're able to get a good sample.
 

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Zach using the power borer for coring trees, speeds things up considerably.  Also note that Jacki is checking the borer at the base of the tree; we tried to sample at ~10cm hts. Note the bole scorch.
 

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Cutting an old stump with a cat-face near plot P6. These were exactly what we were looking for but a lot of the area had been burned and stumps were gone for the most part.
 


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This is not one of our cuts! This was done by Madany in a study back in 1980. He only took cuts on living trees, did not crossdate. We found several of his trees. Check closely on the photo at how the tree is recovering over the cut surface; they are highly resilient.
 

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Why we have to get the stumps before fire is reintroduced; buried in the manzanita, this one will be completely gone after the stand has been burned.

 

The Park has had an active prescribed fire program for several years and much of the upland landscape has seen at least one and in some cases two burns in recent years. Overall the program has had good results. In many of the pine stands the oak cover is at most about 0.5m in height, lower branches on the pines have been reduced and canopy base heights raised considerably, and openings (in some cases quite large) have been punched into the landscape.  Bole scorch of 1-3 m was present on trees in almost all of our burned plots.  Unfortunately for our purposes the fires also considerably reduced the presence of stumps and logs. In many plots, we could see holes where stumps had been but they were completely gone. The best records we found were in unburned stands north of Sawmill Spring on HPP and the ridge above Stave Spring on the East Rim. Stumps were highly decayed but we were able to get some good records.
  

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An example of fire effects from recent burning. Lots of dead and usually down stems, but some surviving trees across the landscape. Note the shrub cover, mainly Gambel oak (Quercus gambelii) and greenleaf manzanita (Arctostaphylos patula).
 

At the end of our two weeks of sampling, I had the opportunity to do a 13-mile overnight backpack down HPP on the West Rim Trail, mainly to see the full extent of ponderosa pine forest in this area. I left the trailhead about 4pm after our last day of sampling. Jacki and Zach dropped off my truck the next day at the Zion Fire Cache; I got down around noon. There are nine designated campsites on the trail and I camped at no. 6.  It was really great to have a chance to hike the full Plateau; there are some beautiful ponderosa pine stands along the trail, and almost all have seen some level of recent fire. There also are some very extensive areas of pine mortality, with the oak or manzanita taking over completely. And of course, as one hikes down the Plateau the canyons and slickrock become more and more lovely! At the very end of the Plateau the world drops away. The last 5 miles drop into the main Canyon, across Navajo sandstone slickrock and cliffside trail ledges, piñon-juniper woodland replaces ponderosa-oak, and canyon wrens start their musical calls. The trail continues to Angel's Landing and it suddenly becomes packed with tourists!  The last three miles involve passing the masses; great to see them hiking up to the Landing but oh what a contrast to the Plateau (I didn't see another person up on the Rim). 

This next sequence of photos is views of vegetation while hiking down the West Rim Trail.
  

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A fairly typical view past Sawmill Spring. A lot of our lower plots looked like this; open stands with very low oak cover (<1m ht); note also that lower branches on the ponderosa have been killed, raising the canopy base heights. These stands look very good, and should be very resilient to future wildfires.
 

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Another view just south of Sawmill Spring. Note also the bole scorch; not as evident in these two photos but it was very present in almost all plots. Note again the shrub cover; to the right in the photo it's taller where there was also greater mortality in the overstory.

 

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Heading down the West Rim Trail the Canyons and slickrock start showing up well, still with scattered ponderosa stands and individual trees.
 

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Looking into Potato Hollow from the south; the trail comes into the Hollow through the canyon in the middle distance, crosses through the scattered trees right below this view (you can barely see it right below in the trees), and then climbs back up on the ridge. A very lovely little valley. There are two campsites (7 & 8) in the Hollow, one you can see in the uppermost pine trees in left center of the photo (i.e., nice spot, but everyone above can see your camp!).
 

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Another view along the trail. Scattered living and remnant pine with old dead oak stems (killed in recent prescribed fires) that likely date back to the last historical fire (preliminary data on the rim above and on the East Rim both show that was in 1879) and lots and lots of new shrubs coming in. But also look at that lovely meadow in the bottom!
 

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I camped in that stand of ponderosa on the far hillside (camp 6).
 

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Next morning at camp 6. I pulled my tent down already (Six Moons Design Deschutes Plus; I highly recommend it); it rained some the night before. This was only my second trip with my new backpacking setup, worked like a charm. BTW, I also highly recommend Mountain House beef stroganoff, that really hit the spot for supper! Note the chair; my base pack weight is under 12 lbs and that includes both a camp chair (Alite Designs Mayfly; 1.53 lbs) and a tripod for my camera (Sirui T-025X; 1.90 lbs). I know the true ultralighters will give me shit about those two, but I have to have a tripod for shooting HDRs and that chair sure makes sitting near the ground a hell of a lot easier for us old folks!
 

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Sunrise and ponderosa the next morning, just before hitting the trail.
 

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Early morning view back towards Lava Point (right in the middle of the photo). Camp 6 is in the stand of pine to right.
 

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Actually sunset the night before.

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Another lovely stand of older trees along the trail, just before it drops off into the canyon. Camps 3 and 4 were not far to the south from this point.
 

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Sunset again.

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Finally, I just wanted to say thank you to a great crew!  Me, Chris, Lionel, Jacki, and Zach. Fun trip, only one major breakdown (that damn latch on the power borer head; I think I have a fix that a local machine shop is working on for me), and we got a lot accomplished. Let's do it again sometime soon...
 

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