September 26, 2020

Dr. Charles Kay: Longterm Vegetation Change in Utah’s Henry Mountain: A Study in Repeat Photography

KayMtHenryFrom Dr. Kay:

“The final report on my repeat photo research in Utah’s Henry Mountains has now been published by BLM. In all, I repeated 608 photographs and over 100 plates are included in the final report. As this is a BLM report, everyone is free to download it, print it off, or to send it on to others. As explained in the report, range conditions have improved markedly since the early 1900’s and riparian areas have recovered despite continued livestock grazing. Soil erosion also has declined and there is no evidence that current livestock grazing is having any major impact on plant communities. This is especially true of woody riparian vegetation along the Fremont River inside Capitol Reef National Park compared to native woody species from the park boundary all the way downstream to Hanksville. Moreover, there is no evidence in any of the earliest photos that large-scale crown fires historically occurred in either pinyon-juniper or coniferous forests in the Henry Mountain Study area——such as the 2003 Bulldog fire that charred 32,000A. Since aboriginal-set fires ceased ca. 1870, forest fuels, including P/J , conifers, and other woody species, have increased, setting the stage for future high-intensity burns.

In closing, I would like to thank Doug Page for providing the GIS maps that appear in the final report, as well as the photo mosaics of the panoramic photosets.”

ABSTRACT:

An extensive search was conducted of archival and other sources to locate as many historical photographs as possible for the Henry Mountains in south-central Utah. Those images were then taken into the field, the original camera stations relocated, and modern pictures made of the historical scenes to evaluate long-term vegetation change and land management activities. In all, 626 repeat-photosets were compiled – 608 by the author and 18 by Earl Hindley. As might be expected, most photosets contained more than one vegetation type. Grasslands were depicted in 152 photosets, sagebrush in 99, pinyon-juniper in 293, mountain brush in 72, aspen in 37, conifers in 145, blackbrush in 71, and woody riparian species in 142. In addition, all photosets were evaluated for plant cover and whether or not the sites showed accelerated soil erosion.

In general, grasslands, sagebrush and aspen have declined, while blackbrush, mountain brush, pinyon-juniper, and conifers increased. Utah’s rangelands are generally in much better condition today than they were during the early 1900s because plant cover has increased and soil erosion has declined. Repeat photos also show that woody riparian vegetation has significantly increased whether or not livestock have been excluded. Contrary to popular perception, coniferous trees and forests are more abundant today than at any point in the past. In fact, the overriding problem on most Utah rangelands has been a major increase in woody plants which, in turn, has dramatically reduced forage production for both livestock and wildlife. As conifers, including pinyon-juniper, have increased so have forest fuels setting the stage for large-scale, high-intensity crown fires, a type of fire behavior that seldom, if ever, occurred in the past. As judged by stand age and forest conditions seen in early photographs, large stand-clearing fires are outside the normal range of historical variability. Historically, frequent, low-intensity surface fires, most likely set by Native Americans, kept most conifers from increasing.

*To view and/or download a copy of this report follow this link.

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