Hotter Temperatures Could Lead To More Wildfires, Damaged Eco-Systems
ST. JOHN: You're listening to Midday Edition. I'm Alison St. John in for Maureen Cavanaugh. The wildfires of 2003 and 2007 have left an indelible imprint on the memories of all of us in San Diego who lived through them and on our ecosystem, one that we're just beginning to understand. All the research suggests that more devastating wildfires are in our future, and we need to learn more about them as we adjust to living in a warmer world. Our guests are Phil Unitt, who say researcher and curator with the museum of birds and mammals. What exchanges to the ecosystem have we seen as a result of the wildfires here in San Diego in 2003 and 2007? UNITT: One of the most striking messages is that our diversity of birds and mammals which is the groups that I and my colleagues have studied, almost every pattern of response you can imagine is exemplified by some species or another, that is there are winners like the Lazuli Bunting, and the black sparrow, and the kangaroo rat whose numbers increased after the fire. And there's the losers, the Pygmy nut hatch, the mountain chickadee whose numbers were really hit down, their preferred habitat was really altered, and the forests recovered so poorly, so we're looking at some very long-term changes in what used to be some very common species. ST. JOHN: Are there some species that have kind of almost been wiped out or are in danger that weren't before in San Diego County? UNITT: Perhaps not quite to that extent. But whereas as I mentioned the pig no mud hatch and chickadee used to be of the most common birds in the Cuyamaca mountains, they're very localized now, very few. We have several species that San Diego was the southern tip of their range, like the brown creeper, the white-headed wood pecker, so that those species were badly hit by the fire, and if they're wiped out here, that means their range retracts back to the north which is one of the predictions made for the effects of climate change. ST. JOHN: When you drive around the back of Cuyamaca there, there are whole hillsides completely dead, it seems like. Are there some areas that have not come back the way we expected them to? UNITT: Yes, the recovery of the pine forest in the Cuyamaca mountains is extremely poor. Gena Franklin studied that particularly and confirmed that, yes, the recovery is poor. I just heard from Bob of the California state parks that they're going to be trying some reforestation this fall. So the natural recovery of the forest has been poor. The recovery of the chaparral, of course, has been much better. But some of those areas burned twice in four years so that if we have an increased frequency of fire, there's going to be many species that do poorly as a result of that. ST. JOHN: Okay. So that brings us to the next question, Matt, which is the increased frequency of fire in the future. Do we know if we're going to be seeing more wildfires in the future? We all sort of feel that's likely, but what do we know scientifically? RAHN: What we can say about the frequency and intensity is that at least for California it's increasingly dramatically. 10 of the 20 largest fires in California's history have happened in the last decade. That speaks volumes to the kind of changes that we could expect into the future. We also know there's this interesting feedback loop that occurs when we have wildfires increase in frequency and intensity. And that means as it burns an area, you have this sort of conversion of habitat type, an impact to the ecosystem and the species, and in a lot of cases, the potential for invasive grasses and other species to colonize that in turn creates obviously a higher risk for fires frequency and intensity. And then when you have a wildfire on the event especially on the scale that we've seen, there's a tremendous amount of carbon dioxide emitted during those events. So that in turn leads to increased CO2 emissions, which is obviously a leading cause of climate change. ST. JOHN: What do you mean by more intense fires? RAHN: As we've seen over the last several decades, the temperatures are warming, and precipitation patterns are changing. And so that obviously has an impact on the frequency and intensity of fires. So they happen more often and the intensity of those fires, the heat and the intensity of the burn increases substantially. ST. JOHN: So you mentioned this feedback loop. So climate change is one of the reasons why we might be seeing more wildfires. What other reasons there are? You mentioned the grasses. RAHN: Invasive species are a big problem in the landscape, and a lot of those are not part of this traditional fire ecosystem which we typically associate with the natural landscape in Southern California. As we have this shift in grasses, we can have an increase and a type conversion in a lot of instances. A lot of it has to do with what was there historically, how frequent the burns happen, and how hot they are. Another problem is the urbanization. A lot of the fires, especially today, well over 95% of our fires in the State of California are not natural events. They're human-caused incidents. So that of course has a lot to do with a shift that's not necessarily related to climate change, but certainly related to urbanization. ST. JOHN: Phil? UNITT: Well, just as we were talking before we came into the studio about the increased frequency of ignitions of fires -- ST. JOHN: That's something the whole county's general plan is designed to bring human development closer to the cities, and less of it far out in the boonies so you can't get fired sparked out where there's not many resources to stop it, for example. But there is that risk, and it sounds like it's increasing. Are there any species which are benefitting from these grasses? Are we seeing new species coming in because of this new invasive species on the ecological level? UNITT: Yes, there are. One example is the Rufus ground sparrow, which one project we're working on now is our centennial resurvey of the San Jacinto mountains, where we're revisiting the site studied by UC Berkeley in 1908. There were no Rufus ground sparrows there at all then, and now they're very widespread, through the San Gregonio pass, that have burned repeatedly in the fires. So it's a bird that likes open slopes with clumps of grass on them. So even though diversity of species as a whole in these areas have decreased, there's still some even native species that take advantage of those habitats. ST. JOHN: How is this being studied? Are you going out there and measuring the number of birds that you see? UNITT: For the San Jacinto study, we have the results of the surveys done in 1908. It's the longest time period we have for such a thing in Southern California. For our fires? San Diego County, we have the results of the San Diego County Bird Atlas from 1997 through February of 2002. So we completed that field work just before the advent of all these fires. So that's one resource we can use. ST. JOHN: There's some longer term effects that we still don't know what they would be? Is anyone making projections as to how our county might look in 50 years? RAHN: Yeah, a lot of research has been looking at what the vegetation communities would look like, what the habitats are both in response to climate change as temperatures and precipitation patterns are altered and shift. But then we also are looking at questions about where the species are going to be distributed. One of the major hurdles in all of this of course is that our conservation planning throughout Southern California has done an admirable job of addressing concerns of endangered species and sensitive species throughout its range. But this occurrence of wildfires and change in frequency and intensity really does throw a brand-new hitch in the plans. And that's complicated more by the growing urban population. Because as we're moving and expanding our population into sensitive areas and we lose habitat, we also lose opportunities for species to respond to shifts in climate. ST. JOHN: Will we ever see a time when really a lot of the forevers we're so familiar with in the back country, that's not the way to describe San Diego County? UNITT: Well, I think we've seen that already. You look at the Cuyamaca mountains now, and what was once a forest of conifers and black oak is now chaparral consisting of ceanothus palmeri. And I don't expect that to generate in my lifetime if ever. ST. JOHN: What and your feeling about the effects on the ecosystem long-term? Are you looking ahead? Is it catastrophic or just change that we have to adapt to? UNITT: Well, I guess catastrophe has been in the eye of the beholder, but it's definitely a profound change that we have no choice but to adapt to. ST. JOHN: In 50-1 hundred years, how will the county look different? UNITT: Certainly those species that are dependant on the coniferous forest, and those that are dependent on mature chaparral, will see many few of and some may disappear all together. And species that are facing multiple challenges simultaneously. This summer, we're working on a study of the gravurria, which lives in chaparral, are and sometimes chaparral that was burned not too long ago. But if its nests suffer a lot of predation, it gets parasitized by a bird that lays its eggs in the nest, and if you add fire on top of all of those, a species that's sensitive to multiple stressors like this simultaneously, it could easily disappear. And we're seeing it apparently on the way out. ST. JOHN: Now, we had three or four years between fires last time. Does that make a significant difference? Does five years make a defense to how it can recover? RAHN: Well, I think there have been all sorts of studies that look at fire frequency, sort of on a natural scale. And certainly it was never a five or four-year event. We're talking about more of a decade or longer between fires, and that's sort of how our ecosystems have adapted to this. So for some species like the Tecate Cyprus, for example, that could be devastating for that particular species because it is one that's -- responds to fires, and the cones are serotinous, so they drop seeds after being exposed to a fire event. But if you burn an area more frequently in between the ability for the tree to grow up large enough to drop cones again, you could cause local extirpation of species inadvertently. ST. JOHN: That's a word we might be unfortunately hearing more of. Are you saying the scientists are pretty much assuming that ten years between fires is not realistic? RAHN: Yeah, a lot of this has to do with our ability to manage fires on an ecosystem level. CAL FIRE does an outstanding job of minimizing fire impact because the majority of the these fires are manmade. 95% or more of the fires in California are kept below 5 acres. That's a remarkable job. But one of the other key components needs to be postdisaster response planning. So after a fire, how do we respond to that? How do we manage the ecosystem? Restore habitats and insure the long-term viability of our species. ST. JOHN: Give us a sense of what you wish everybody in San Diego was doing to adapt to this kind of a future. UNITT: We have to recognize that these fires are going to happen, that resolving the conflict between rural dwellers who could like the state to provide fire protection and urban dwellers who would like the rural dwellers to pay for that protection as being discussed on KPBS just an hour after. I think my mother who grew up in descanso, and I take her up to the mountains now, and she's just heartbroken at what we've lost. And it's very sad but we're to the point now that we have to accept it and find beauty in what's still there. ST. JOHN: Okay, I think that's the place we're going to have to end it. Thank you very much for coming in.
As record-high temperatures are noted in thousands of areas across the country this summer, scientists are keeping an eye on the probability of an increased number of wildfires in San Diego and the West.
Plants and animals are already struggling to recover from the 2003 and 2007 catastrophic wildfires in San Diego County. But those fires caused huge changes to the region's fragile eco-systems.
The Cuyamaca Mountains were covered with coniferous Jeffrey Pines until the 2003 Cedar Fire. According to Philip Unitt, curator of the Natural History Department's Department of Birds and Mammals, the Jeffrey Pine has not returned to the area at all.
The loss of the pine means the birds and mammals that depended on those trees no longer have a habitat.
Matt Rahn, of San Diego State University's Environmental Sciences Department, describes what he calls the climate change "Positive Feedback Loop." Increased temperatures lead to more frequent and more intense wildfires, which produce large amounts of carbon emissions, which lead to increased temperatures.