| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Letters to the Editor Chaparral on Fire I was pleased to see an accurate portrayal of the biological responses after 2003 California firestorm in your recent "Fire Followers " article. Unfortunately, a caption describing chaparral reinforced one of the most frequently repeated misconceptions about the system: "Decades of fire suppression nearly smothered this distinctive rock formation in chaparral..." The misconception that fire suppression has caused an "unnatural accumulation" of shrubbery in southern California appears to be based on the misapplication of studies relating to dry ponderosa pine (Pinus ponderosa) forests showing that undergrowth has increased over the past century due to successful fire fighting activities. In the past, surface fires burned through these forests at intervals between 4 to 36 years, clearing out the understory and creating a more ecologically balanced system. However, this conclusion has nothing to do with California shrublands. Analysis of historical fire data has shown that not only have fire suppression activities failed to exclude fire from southern California chaparral as they have in ponderosa pine forests, but the number of fires is actually increasing in step with population growth. The area burned per decade in southern California counties has not significantly changed over the past 100 years. The caption also suggested that, "the cleansing flames of wildfire left a clean slate for new plants to take hold. "This reinforces the assumption that older chaparral becomes decadent or unproductive and "needs" to burn every 20 to 30 years in order to renew itself, suggesting the necessity of using prescribed burns as a resource management tool. Field research has failed to support this notion. Chaparral stands a century old continue to maintain productive growth, living material steadily increases over time, and shrubs in older chaparral communities are not constrained by limited soil nutrient levels. While it is true some individual specimens of certain Ceanothus species will die as a stand reaches 20-40 years of age, others remain an important part of chaparral stands over 90 years old. When spaces do appear in the chaparral, living plants quickly fill the void. Not only do mature shrubs continue growing over time, but seeds from the majority of species common to north facing, mesic chaparral stands require long fire-free environments before being able to germinate. Moisture-protecting shrub cover and leaf litter are needed to nurse the seedlings along. Many mature chaparral stands are just beginning a new stage of growth after fifty years of age. Old-growth chaparral in excess of one hundred years old remains a productive, dynamic ecosystem and represents one of the region's most valuable natural resources. Understanding this concept is important because chaparral is incredibly sensitive to increased fire frequency. When the interval between fires drops below 10 to 15 years, many chaparral species are eliminated and the system is typically replaced by non-native, weedy grassland. If the public thinks chaparral needs to burn and that older stands are unhealthy, it will lead to land management policies that could threaten the system's continued existence. Richard W. Halsey Seahorse Dilemma Wonderful piece in California Wild. It's one of the best treatments of the traditional medicine challenge facing marine conservationists that I've ever read. James Hrynyshyn Nervous Elk I thoroughly enjoyed your article "Killing Me Loudly" and was particularly intrigued with Scott Creel's research in Yellowstone National Park. I've followed the pendulum of snowmobile bans and reinstatements and thought Mr. Creel's research supports the National Park Service's original phase out. I wondered if Mr. Creel is planning on conducting research on glucocorticoids (GC) in elk in a park that doesn't have a top predator like the wolf, but has a snowmobiling season. Such a study might rule out the wolf as the reason for increased GC in the Yellowstone elk. I was also curious if harsh winter conditions, stress on the carrying capacity of the environment and a shortage of food might also cause an increase in GC levels in elk. Seth Shteir Scott Creel replies: I've been collecting GC data from four elk populations that differ in exposure to wolves for the past three years, so we will have data on the likelihood that wolf presence affects GC levels in elk, but this work isn't directly related to snowmobiling. Snow depth does affect GC levels in elk. That effect was considered in the original paper that was discussed in California Wild. Deeper snow equals higher GC levels, particularly in old individuals.Department of Ecology Editors Under Siege I would like to correct a mathematical error in the "Traces of Technetium" letter (Winter 2005, p. 50). After one half-life, half of the original isotope remains. After two half-lives, one quarter, and after three half-lives, only one eighth of the original isotope remains. Following this pattern, we have halved ten times after ten half-lives. Therefore only one 1024th (1/210 = 1/1024) of the original isotope remains. The quantity of an isotope has been reduced by a factor of 1024, not 1024. Brian Jue The error was caused, in part, by the typographical limitations of email. I'm outraged and disgusted that you misspelled the word 'Siege' right there on the front cover of your otherwise great Winter issue of California Wild. There's no excuse for this typo. Doesn't anyone do any proofreading at your facility? Disgusted, Hans Roenau Mea culpa, Kieth Howell, Editor |