S.D.S. in the " other " Pima canyon, Pt. #3 Tough lessons in resilience and responsibility among scorched earth

[Silas_Sancona]

As mentioned, aside from spending time looking for various plants while here, another " item " on the days menu was getting up close with the post- fire effects of a large fire that charred a majority of the Catalina Mountains, including parts of Pima Canyon itself. While this particular conflagration started naturally ( by lightning during a brief, dry Thunderstorm passing overhead ) the fire's subsequent spread and effect on the landscape were enhanced by an on going change in the composition of plants in the landscape, partially spurred by humans, and on larger, going changes which themselves are being enhanced by us.

While i'll try to keep this discussion as contained as possible, there's a lot to unpack.

Part of understanding the significance of fire in the desert is understanding how the desert, and surrounding environments evolved with and respond to fire in the first place.. and why what happens " out in the desert " effects everything else, a lot of which people depend on.

In a nutshell, ..and unlike some ecosystems that rise above it, the Sonoran Desert did not evolve with fire.. Plants here sacrificed fire tolerance for drought and sun tolerance.. While numerous " bunch"-type perennial grasses grow here and there in the desert, these grasses are always well spaced in the landscape and rarely allow a fire to burn intensely enough to kill everything. This contrasts other environments such as Grasslands and scrubby/shrubby " Chaparral " which both evolved with fire. Most forests did as well and normally respond favorably to low intense but regular fires.  In the past, large grazing animals and Native Americans managed these places so that they never became too overgrown. This benefited both the people and animals.. and the environment itself.

As both were removed from the land, or were hunted into extinction.. or replaced with ranching practices which can cause more damage, let alone introduced exotic grasses/ other aggressive, weedy plants that can out compete native species, ..and, to put it simply, a society which became " terrified " of fire, the negative effects of this started mounting.. In California for example, those famous " Golden Hills " many think of when thinking of the state are nothing but introduced annual grasses (  and other European pasture weeds ) that took over after introduction. Native grasslands there look much different.. somewhat resembling those in the Plains.. " Drifts of bunch grasses here and there with plenty of space for native annuals, perennials, bulbs..etc to grow " would be one way of describing them.

In the Deserts, most " cool season " grasses have a tough time establishing themselves, which is where a sinister Perennial grazing grass from Africa comes in. Buffelgrass, a similar looking relative of Fountain Grass ( also extremely invasive ) quickly started spreading into the Sonoran Desert ( and Tropical Deciduous Forests/Thornscrub further south ) once introduced and continues it's campaign of terror as it spreads across more areas. Unlike native grasses, Buffelgrass has no natural enemies and can pioneer any nook and cranny it's seeds drift into. It also evolved with fire and can withstand extreme drought. 

Any fire that ignites where Buffelgrass has established itself will spread faster and burn hotter. Because of this, anything that can't withstand high intensity fires can be wiped out. This includes Saguaro and pretty much any other succulent-type plant. In the wake of the fire, this grass easily re-generates and continues it's spread. Repeat the cycle, loose more natives.. convert the landscape to nothing but Buffelgrass. This is how it is maintained for grazing.

In other parts of the west,  a couple other introduced Annual grasses are spreading across the deserts and near-deserts such as the Mojave and across the Great Basin with similar effects. The destructive fire in Joshua Tree stands in Mojave Nat. Preserve last year was partially a result of these invasive pasture grasses.

Interestingly, in Mexico, when not burned regularly or abandoned, Buffelgrass pastures will slowly transition back to their native state as pioneering native plants of the TDF ( Tropical Deciduous Forests ) re- establish themselves and shade out this grass. But this takes time.  In the Desert, such recovery may take much longer, if it occurs at all.  The building blocks, such as Cryptobiotic soil crusts which help stabilize loose soil, and plants like Spike Mosses, which help build fertility in the soil.. let alone provide shaded places/extra moisture for seedling plants/ Cacti to grow can take decades to return after disturbance.  This is one reason the campaign to " reign in " Buffelgrass has gained a lot of traction recently across the state. Same with it's often sold in nurseries cousin Fountain Grass, which is trying to spread into the canyons around the Catalinas and other areas.. While not quite as aggressive as Buffelgrass, at least here in the desert, it too negatively impacts areas it invades. Responsible nurseries -and their customers- both locally and in many other areas of the country have stopped selling it/ asking for it. Simply put, Don't plant it.. no matter which variety.. there are many great native alternatives that provide the same effect in the landscape to seek out.

In the case of the Bighorn Fire, the path of the blaze somehow avoided those parts of Pima Canyon -and other lower elevation portions of the Catalinas where Buffelgrass is more established which is one reason nearby homes were not effected by such an ominous looking fire bearing down from above. Still, the fire did lay waste to some parts of the canyon providing both a lesson in how tough the desert, and surrounding environment can be, and how tolerating/ignoring aggressive invasive plants, let alone planting them can forever wipe the habitats we admire off the face of the earth.

It's one thing for the Upland section of the Sonoran Desert to slide into a more Tropical Thorn scrub kind of look some day, if that isn't occurring already.  It's not wise to allow this same area to be willfully altered to such a degree that it resembles a degraded version of African Savannah, with little diversity, ..just Buffel ( or Natal ) Grass and some Mesquite. Some animals might adapt to that, most likely won't.

For those who make the case of " Well, not all exotics are bad " Yes, they have a point.. Not all  non-native plants threaten to forever alter habitats they may escape into..  but, as has been pointed out by numerous ecologists, botanists, etc.. plants from other parts of the globe often will not have the "checks and balances " in tow they evolved with when planted across oceans, as a pose to planting something from say Sinaloa in Tucson which, oppositely, likely evolved with the same ( ...or near relatives of.. ) those same checks and balances at some point in time in the past..  In a changing climate, which we have contributed to, where plants from neighboring regions will likely seek new homes in neighboring states, this balance becomes even more important. 

As the saying goes, " Choose wisely, ..and responsibly.. "

For much more regarding the effects of the fire, and a glimpse of Sky Island ecology, the U of AZ put together a 3 part webinar on the fire and other topics worth checking out, titled " Fire on the Mountain " if interested.. Skipped ahead and listened to the 3rd part of the presentation. Pretty informative, and while focused on the region, mirrors thoughts and challenges facing many parts of the West, and globe in general.

Onto some pictures...
 

[Silas_Sancona]

 From the looks of it, fire was of low to lower-moderate intensity where it moved through, hopping over some spots, while roasting others. This is confirmed by fire intensity maps i looked over. Regardless, somewhat bleak scene of burnt vegetation and bare soil. At the same time, plenty of survivors, and some new life among the ashes, despite our ongoing punishing drought. Unfortunately, due to how dry everything still is/ what little has germinated this winter -to help bind bare earth-, the potential for damaging flash flood related events remains once the rains return, hopefully this summer.

With the reality of potentially longer droughts, fires that occur too frequently in this part of the country risk completely altering every habitat from the desert floor up into the mountains. This is already being noticed in other states where recent drier/warmer winters make it harder for the seeds of plants that grew there, before a large fire swept through, are either having a tough time re-establishing new populations, or simply failing to germinate at all.. and being replaced by various plants from lower elevations which can tolerate this drier/warmer new world better.  Guaranteed, if this is occurring here, it is happening pretty much everywhere else.

Have walked through other post-fire areas ( back in California ) have to say, compared to them, and some areas this fire torched further east, damage could be much worse ( At least this isn't a complete moonscape )

Overall landscape:










Charred Dasylirion:


Agave palmeri ( Or chrysantha ).. on the rebound..












Torched Saguaro ..and Ocotillo.






..Opuntia and Ferocactus ( Barrel cactus )




A bleak landscape, but it will recover.. That said, it is a landscape vulnerable to disappearing if we forget -or choose- not  to value it's importance.

[tropicbreeze]

Buffel grass is a significant weed here in southern arid/semi arid areas but is not an officially declared weed. Probably due to pressure by graziers on the government. But the problems created are much the same. It's a vigorous plant that out competes others and robs them of nutrients. It carries high intensity fires which damage other plants. However, it recovers rapidly and quickly recreates a fire hazard again. One of the vulnerable plants affected by it here is Livistona mariae ssp mariae. Seedlings are slow growing and not fire tolerant.

In the north we have Gamba Grass, Andropogon gayanus, which can grow 3 to 4 metres tall. It starts growing later than other grasses but then grows longer into the Dry Season. Early hazard reduction fires won't kill it. It cures well into the dry season. Gamba fires that time of year are infernos that kill most other plants including tall trees, and also put firefighters at very high risk.

[Silas_Sancona]

15 hours ago, tropicbreeze said:

Buffel grass is a significant weed here in southern arid/semi arid areas but is not an officially declared weed. Probably due to pressure by graziers on the government. But the problems created are much the same. It's a vigorous plant that out competes others and robs them of nutrients. It carries high intensity fires which damage other plants. However, it recovers rapidly and quickly recreates a fire hazard again. One of the vulnerable plants affected by it here is Livistona mariae ssp mariae. Seedlings are slow growing and not fire tolerant.

In the north we have Gamba Grass, Andropogon gayanus, which can grow 3 to 4 metres tall. It starts growing later than other grasses but then grows longer into the Dry Season. Early hazard reduction fires won't kill it. It cures well into the dry season. Gamba fires that time of year are infernos that kill most other plants including tall trees, and also put firefighters at very high risk.

It's awful stuff and those fighting it's spread have been going to incredible lengths to bring it under control where they can.. Ironwood Forest National Monument is probably one of the most remote parts of the Arizona side of the Sonoran Desert but volunteers will regularly head out to some spots in the Silverbell Mountains ( N.W. of Tucson ) to pull Buffel, trucking it back by the bed full. There is some use of chemical control as well but is very carefully applied for obvious reasons ( where it can be used ) Other trips are made to the Catalinas/ surround areas regularly as well.. While awareness is getting better over time, efforts to control/ eradicate on going, stuff is still trying to spread along highways.

Even crazier is i have heard there has been talk of breeding Buffel that is more cold tolerant.. If such a need exists, focus should be on native grasses, not this stuff, Natal or Gamba.