California “Grasslands” vs. Altered State(s)
We’re pretty used to California’s “golden, rolling hills”. For many of us they are the backdrop of “home” and we generally don’t question their widespread abundance, nor their annual death at the end of each rainy season. For those who’ve given them much thought at all, realizing they’re now dominated by nonnative annual grasses, there has long been a tendency to view them as representative of original bunchgrass lands, degraded by livestock “overgrazing” during the couple centuries since Europeans first came to these lands. But while there is partial truth to the overgrazed notion (see blog post 3, How Watersheds Relate to Groundwater, and the latter part of 4, Think Outside the Basin, for example), that must be recognized as an outdated paradigm. If more folks become cognizant of that, perhaps we can move to restoring these lands for their original watershed functions (rather than as fantasy grasslands, which just gets us more noxious weeds) as well as for biodiversity and even economic well being.
[Caveats: This page is longer than any other on this site to date, but is perhaps overdue, though it’s posted little more than six months after getting the rest of the main website up. This piece doubtless gets a bit wonkier than other pages Verna has strived to craft for more interdisciplinary appeal. But for those of similar botanical wonkiness to Verna, the caveat is that we strive here to reach a multidisciplinary audience and so the following dispenses with some ecological theory that botanical/ ecological wonks might expect. Apologies in advance to those who care not for scientific nomenclature – in this case it simply can’t be avoided and should help clarify for those less “allergic” to the lingo.]
Critiques of the Predominant California Grasslands Paradigm
Over the past couple decades, this view of original pristine perennial grasslands has become recognized as a well-entrenched “paradigm” and one that is very (too) gradually yielding to other perspectives. Credit is due to Jason G. Hamilton, studying at UC Santa Barbara in 1997, for getting the conversation started in print with “Changing perceptions of pre-European grasslands in California” (Hamilton 1997).
Hamilton methodically points out how the notion of California grasslands having all been homogeneous expanses of lands dominated by the perennial bunchgrass purple needlegrass (Stipa pulchra) [our official state grass, BTW] came to prominence was based on faulty but unquestioned premisses and was especially questionable with regard to arid to semi-arid regions of central and southern California.
Hamilton (1997) titles one section of his paper, “Acceptance of the Paradigm”, stating,
This paradigm consisted of two elements: (1) ideas concerning the composition and distribution of ‘California bunchgrass grassland’ and (2) the grouping of ‘grasslands’ in the entire Central Valley, the central and southern Coast Ranges, and southern California into a single community type.
He goes on to enumerate acceptance of the paradigm by several scientific journal articles and books, then by researchers at U.S. Department of Agriculture, various California state agencies and the University of California Agricultural Experiment Station. He notes that the “dominance” of purple needlegrass was thereafter “proclaimed” in the standard California flora, specialized floras and and general treatises on California vegetation (all of which were part of Verna’s botanical schooling) then subsequently in broader geographical treatments of North American and world vegetation.
This acceptance of the paradigm came despite robustly supported alternative paradigms extending to contemporary times, which may be summarized as 1.) dominance of chaparral (including scrub and oaks) vegetation over much – not necessarily all – lands currently dominated by nonnative annual grasses, 2.) dominance by annual forbs (broad-leaved herbaceous plants – mostly “wildlfowers”), especially over the valley grasslands, referring to the work of Paula Schiffman, discussed below, and 3.) vegetation type determined by soil characteristics, the most current then and local citation being Keeley (1993), which is also cited herein on the California Case page. While Hamilton emphasizes the soils aspect of Keeley’s conclusions, Keeley (1993) considers slope aspect (compass direction the slope faces) as another important variable.
Verna actually accepts all three of these alternate paradigms, viewing natural California vegetation as comprised of mosaics alternating based on specific environmental conditions at any given site, but also incorporating knowledge of the likely prehistorical impacts of aboriginal burning, touched upon in blog post 4, Think Outside the Basin and further supported by Jon Keeley in subsequent works noted below.
Hamilton (1997) observes that there is [or at least, should be] little doubt about the pre-European vegetation being “oak forest, chaparral, or coastal sage scrub”, given the well-documented evidence of widespread clearing of such vegetation in California as a matter of public policy during the 20th century, let alone attitudes that doubtless prevailed before that time with respect to private lands, at least. Since that is the subject of Verna’s 6th blog post, Ball and Chain & Other Links, we’ll just state that as fact here. Please refer to that post for more details.
As Hamilton noted, physical evidence of the prehistorical presence of purple needlegrass has been documented for northern California locations currently dominated by nonnative annual grasses in the form of opal phytoliths (microfossils high in silica content) likely left by that bunchgrass (Bartolome and colleagues 1986), but that “does not preclude the possibility that the original vegetation was savanna or woodland” (Hamilton 1997), rather than bunchgrass grassland.
That purple needlegrass is well adapted to frequent burning had been established by the mid-20th century. Bartolome and Gemmill (1981) further established its adaptation to various anthropogenic disturbances.
As for the Central Valley, Hamilton (1997) points to Wester’s (1981) excellent treatment, which is freely available online. Among Wester’s observations are that early accounts of bunchgrasses were confined to the northeastern portion of the San Joaquin Valley.
While Hamilton notes that contemporary reviewers have been more careful than those of the early 20th century and generally tend to reverse those earlier depictions of
vast, relatively homogeneous perennial grasslands, and portray the pre-European Californian ‘grassland’ vegetation as a complex mosaic of different herbaceous communities with the particular species composition depending on climate and local conditions. Nobody has yet declared that perennial grasslands were unimportant components of California’s vegetation, but there has been an increasing recognition that there are species differences and changes in relative abundance of perennials and annuals between north and south, Coast Ranges and Central Valley, and within the Central Valley, depending on specific site conditions. . . .
We will never know with certainty what the pre-European vegetation of large portions of California looked like. Nonetheless, the evidence strongly indicates that the poetic images of [purple needlegrass]-dominated bunchgrass prairie blanketing vast expanses of the Central Valley and other ‘grassland’ areas of California are not accurate. There probably were stands of bunchgrasses in the northern Central Valley on rich soils and in some areas of the Coast Ranges. The central and southern Central Valley was probably a complex mosaic of plant communities with bunchgrasses becoming less and less important toward the south. In these areas, communities of annuals probably dominated, with forbs being more important than grasses. Finally at the extreme southern end of the Central Valley, a desert scrub vegetation probably dominated.
As Hamilton accurately points out, the prevalence of this paradigm of pervasive pre-European California grasslands dominated by purple needlegrass has led to a disproportionate amount of research effort and funding being concentrated on restoration of this species, “at the expense of others”. Verna can attest to that based on personal observations throughout her professional career that continue through the present.
Burrowing Mammals & Annual Forbs
Hamilton’s (1997) effort was accompanied by Paula M. Schiffman’s 1997 talk, published later (Schiffman 2000) asking whether a paradigm shift was in order, referring to the inherent disturbance of burrowing mammals ubiquitous in California’s so-called “valley grassland” and with specific reference to Carrizo Plain. While scattered patches of native bunchgrasses there attest to their ability to cope with xeric conditions, the legion of burrowing mammals would preclude their establishing extensive stands. She proposes that these lands would have originally been dominated by annual forbs.
Whether or not those observations apply to other California “grasslands”, the ecological and ecohydrological effects of burrowing mammals in cannot be overlooked.
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From Joseph Grinnell (1923) we learn that more than half of the mammal species and subspecies known in California belong to the order Rodentia and nearly half of those are burrowing rodents. Thus, burrowing rodents comprise roughly a quarter of California mammal species. That fact is made more meaningful by Grinnell’s notation,
that only one of the seven genera of mammals to which our burrowers belong is represented in the United States east of the Mississippi River. (The genus Citellus of ground squirrels furnishes the exception; two species of that genus go as far east as Indiana.) From a possibly economic bearing, with respect to digging, moles and earthworms, though ecologically not at all homologous, seem to take the place in the far eastern states that the burrowing rodents take here.
The line of demarcation, eastward of which the burrowing type of rodent begins to disappear, is, approximately, the 100th meridian. In other words, there is a north and south line of transition between two major faunal regions which roughly coincides with this meridian. The limitations of the animals in question undoubtedly have to do with the physical peculiarities of the regions east and west of the 100th meridian. These peculiarities involve differences in atmospheric humidity, in rainfall, and, of seeming major importance, the sharp alternation of dry and wet season which occurs to the westward. Linked up with these conditions, there is, probably, in the West a relatively greater abundance of plants with nutritious roots or thickened underground stems (corms, rootstocks).
… Of the five types of burrowing rodents in California, the most widespread, in the aggregate the most abundant, and certainly the most effective in its equipment for turning over the soil, is the pocket gopher (Thomomys); . . . An examination of a pocket gopher shows its structure throughout to be remarkably specialized for burrowing into and through the ground.
Grinnell dwells compellingly on the features of pocket gophers and their influence on soil dynamics. Elaborating on how perfectly their morphology fits their ecological niche as a burrowing rodent, he notes the longevity of that morphology in its present environs.
The greatest of all agencies of erosion in the Sierra Nevada, the glaciers, so stressed by John Muir, have now ceased to operate, and the less obvious agencies come into prominence. The element of time granted, we are able to conceive of vast accomplishments on the part of even so humble a contributor as the pocket gopher. Gophers have been at work as gophers of modern types since Miocene times. (Grinnell 1923)
Grinnell points to the abundance of gopher skulls found in the Rancho La Brea tar pits.
The exact horizon in which they are found is that in which are also found the saber-toothed tiger, the ground sloth, camels, mastodons and dire wolves. That horizon has been assigned to the Pleistocene epoch; and geologists have estimated that the time elapsed since the deposit of the materials representative of that horizon is computed in “tens and even hundreds of thousands of years.” A remarkable thing is that a study I have just made of the gophers of Rancho La Brea in comparison with the species existing in the same vicinity today, shows they are identical in every respect.
Grinnell’s (1923) footnote there:
The species and subspecies is Thomomys bottae pallenscens.
Thus, many of our modern California soils have coevolved with the influence of pocket gophers. Coevolution appears demonstrated in that,
… no two of the 33 species [of pocket gophers] occurring in California exist in any one locality. Just one kind lives in a place, to the exclusion of all other kinds. There is probably close correlation of structure with peculiarities of the terrain, as for instance, those shown by loamy sandy and rocky soils. . . .
Carrizo Plain boasts a particularly rich array of burrowing mammals, so the Grinnell quotations above represent only a sample of the likely ecological interactions.
Bunchgrass Dominant Paradigm
Then, continuing the paradigm theme, Glen Holstein offered, “Pre-agricultural grassland in central California” (Holstein 2001) in which he gave the bunchgrass dominant paradigm the “BDP” acronym. He bases his comments on observations and field analyses conducted at The Nature Conservancy’s Cosumnes River Preserve, southern Sacramento County, along with some literature review. His over-arching conclusion is that pre-agricultural valley grassland was dominated not by bunchgrass, but rather the rhizomatous (spreading vegetatively by runners more than by seed, like certain lawn grasses) native, creeping or beardless wild rye (Leymus, now Elymus triticoides). Note that botanical and even common plant names are subject to changes over time and we’ve so far spared the reader details of such changes for purple needlegrass, given that we strive for interdisciplinary understanding herein.
Holstein (2001) offers examples of historical documentation of what likely referred to this rhizomatous grass at other mesic (moist) sites in northern California, including the south San Francisco Bay area, but in the Central Valley, none farther south than Mokelumne River.
Verna’s take on this work is that it is convincing with respect to the mesic sites typically occupied by creeping/ beardless wild rye today and which were indeed most likely converted to agricultural, then in many cases, urban land uses. These are generally lowland sites, not foothill uplands that currently comprise most of the rangelands of concern for Rainfall to Groundwater. Creeping/ beardless wild rye can be important for riparian/ drainage/ wetland zone restoration in the hills but is unlikely to do well on dryer upland slopes.
But Holstein goes too far when, in his Conclusions, he states that his argument against
the BDP does not mean the end of knowledge about pre-agricultural California grasslands or resurrection of bizarre theories that they were once covered by chaparral (Hamilton 1997, Cooper 1922).
(Holstein 2001, emphasis added)
His reference to the astute and much more thorough literature review of Hamilton and the geographically more diverse field observations of Cooper as “bizarre” suggest questionable scholarship on his part – like his reading of both works was either hasty, limited or both. Certainly neither suggested that valley lowlands were once covered by chaparral. And his inference that his conclusions apply to all of California southward of his study area are simply specious, missing some of the point Hamilton made about more xeric regimes to the south, both coastal and Central Valley. Perhaps that is why the freely available (scanned) pdf available on his former employer’s website is missing the final two pages of the main text (including “Conclusions”), but not the rest of his references (?).
Present Status of the Proposed Paradigm Shift?
Interestingly, where Hamilton (1997) perceived a paradigm shift in progress, a June 2018 Google Scholar search of literature citing his paper turned up 112 citations, but very few of those works diverged much from the prevailing California grasslands paradigm.
A special issue of Fremontia, published by California Native Plant Society (CNPS) in 2011, highlighted “California’s Prairies and Grasslands” but tends to focus more on valley grassland than adjacent foothills rangelands. Where it gets into rangelands it mostly conveys the importance of conservation and collaboration, offering, for example, an homage to grazing for controlling exotic annual grasses around vernal pools (Alvarez 2011) . Note that Rainfall to Groundwater also seeks to conserve rangelands through collaboration, but just doesn’t accept the status quo dominated by exotic annual grasses, including noxiously invasive species, as most are to begin with, depending on one’s paradigm. Please also note: What does Rainfall to Groundwater offer for vernal pools? Glen Holstein, by then a retired CNPS volunteer, contributed the article, “Geology, climate and California prairie distribution” (Holstein 2011) to that volume. Again, little insight is offered regarding regions south of Sacramento County. See also my comment below on his overemphasis on Burcham’s (1957) map of so-called “pristine” vegetation.
In general, these paradigm issues have been ignored by the rangeland management crowd, with the noteworthy, exemplary exception of Sheila Barry and colleagues (2006) “California native grasslands: a historical perspective, a guide for developing realistic restoration objectives”. Verna considers this exemplary given that the rangeland management community has been predominately focused on providing the grass needed by the European heritage cattle stock since the profession began by the early 20th century (Talbot and Cronemiller 1961). BTW, that last citation is both entertaining and enlightening, so well worth downloading while it remains freely available online. It describes some of the history of the “range wars” noted in blog post 3, How Watersheds Relate to Groundwater.
Influence of Soil Type & Slope Aspect on Existing Vegetation
Returning temporally to one of Hamilton’s (1997) citations, Jon Keeley’s (1993) “Native grassland restoration: the initial stage – assessing suitable sites” also had a decided impact on Verna’s thinking, as noted on the California Case page. As noted above, Keeley’s research on a site in southeastern Ventura County documented that stands of native perennial bunchgrasses occur predominantly on north and east-facing slopes, on deeper and rock-free soils, and on soils with a higher clay content than the introduced annual grasses, which predominate on rocky, shallower, south and west-facing slopes, with lower proportions of clay. He argued that locations currently occupied by the introduced annual grasses are actually suited for coastal sage scrub and chaparral, and that those were the likely land-covers prior to anthropogenic disturbance (Keeley 1993).
As it happened, several years later Verna performed reconnaissance and rare plant surveys on a series of private sites not far from where Keeley drew his (1993) conclusions – both were in the Santa Susanna Mountains but Verna’s work was on the north side of the range in northwestern Los Angeles County. The lands Verna surveyed had been subject to comparatively less historical disturbance overall, and they remained mostly covered with scrub groupings, although these bore evidence of a fire there approximately twelve years prior to her initial visit in 1998.
John Rusk from Berkeley, CA, United States of America, J20160401-0073—Salvia leucophylla—RPBG (26007149150), CC BY 2.0
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On one of the larger parcels, with an overall north-facing slope aspect and soils with relatively high proportions of silt, purple sage (Salvia leucophylla) dominated the land-cover, along with associated coastal sage scrub dominants, California sagebrush (Artemisia californica) and chaparral mallow (Malacothamnus fasciculatus), as is the case for much of these north-slope foothills of the Santa Susana Mountains, straddling a transition zone from coastal to Mojave Desert climes, just west of Santa Clarita. The purple sage apparently had something to do with the relatively undisturbed character of the land, in that it had long been valued for the honey beekeepers could produce there. The resident beekeeper told Verna that the history of beekeeping on those lands extended back into the mid-1800s, and that grazing had always been very light, throughout its history.
Within this matrix, stands of California Walnut (Juglans californica) Woodland (Holland 1986) hugged the steepest higher slopes, while mid-slope patches of California, or foothill, ash (Fraxinus dipetala) formed clusters of what was best described by Holland’s Northern Mixed Chaparral classification. The canyon edges were cloaked with Coast Live Oak (Quercus agrifolia) Woodland, whose extent had likely been diminished through historical human activities, but it appeared to blend and intermingle with the coastal sage scrub species.
Where natural or anthropogenic disturbance, including fire and the common ridgeline ranch roads, thinned the scrub canopy on the north-facing slopes and ridgelines, perennial bunchgrasses assumed prominence, especially oniongrass (Melica imperfecta) and foothill needlegrass (Stipa lepida) with frequent one-sided bluegrass (Poa secunda ssp. secunda). Nodding needlegrass (Stipa cernua) formed rather linear stands along the floodplain of a lowland intermittent stream. The native annual grass, small fescue (Festuca microstachys) graced the understory of a “perched” oak woodland stand of fifteen trees hugging a niche on a steep north-facing hillside. It may have been a remnant of an earlier, larger woodland, now occupied by the purple sage scrub, or may have simply been a pocket of particularly deep soil. Giant wild-rye (Elymus condensatus) stoutly stabilized the steep, north-facing drainages and anthropogenic disturbances along the canyon bottoms.
In contrast, the Non-Native Annual Grassland (Holland 1986) on the site occurred in the expected patterns, as summarized by Keeley (1993) — over sites of anthropogenic and natural disturbance along canyon bottoms, and on the south- to-west-facing slopes. Viewed on an aerial photo, the topography of the land could be clearly discerned by this patterning of the vegetation, as is generally true throughout the state, except where wholesale type conversion to nonnative annual grasslands was long ago achieved. This is especially noteworthy, given that this property had reportedly received no more than light grazing throughout its history, favored as it was for its purple sage honey, along with some dividends of limited oil and/or gas resources that had been tapped during the Great Depression.
This is one among many examples, but a particularly salient one, of apparent relatively natural distribution patterns of native perennial grasses among shrubs. Verna’s observation on this particular site, given historical management, was that the bunchgrasses persisted beneath the maturing shrub cover wherever small gaps in the shrub canopy appeared. And they appear ready to reestablish prominence when the anticipated wildfires sweep through, as they did again in 2003. But human-caused reductions in mean fire intervals could threaten even these re-colonizers.
Native American Impacts on Fire Regimes of the California Coastal Ranges & Cooper (1922) Again
There is so much evidence to support this hypothesis that the general resistance of our culture to fully recognize anthropogenic changes prior to European colonization of North America appears due primarily to cultural bias. As Keeley notes, earnest students of the environment have covered this ground, dating back at least to the early 20th century. He cites and quotes from Cooper (1922). Complementing the excerpts Keeley (2002) included is the following from Cooper (1922), who, in turn, quotes well-known botanist Willis Linn Jepson:
It has been stated that fire favors the extension of the chaparral at the expense of the forest. It is also true that fire, if it occurs with great frequency, favors grassland at the expense of the chaparral. A single burning of chaparral will result merely in a crop of stump sprouts and greater density than before, but yearly burning will inevitably destroy the brush completely or prevent invasion by it. Cattlemen and sheepmen in the early days, according to unpublished Forest Service reports, were accustomed to fire the brush annually in the foothills to destroy it and thereby improve the grazing conditions. This resulted in a great increase of grassland at the expense of the chaparral. Such recent events, however are of small importance compared with the effects produced by the aboriginal population. The following quote from Jepson  is of interest in this connection:
The herbaceous vegetation [in the Great Valley] in aboriginal days grew with the utmost rankness, so rank as to excite the wonderment of the first whites. …
This dense growth was usually burned each year by the native tribes, making a quick hot fire sufficiently destructive to kill seedlings, although doing little injury to established or even quite young trees. (Jepson 1910)
Dr. Jepson writes concerning the sources of his information:
The statement made in the Silva re periodical burning rests upon evidence gathered by myself from members of the Nyah, Hupa, Pomo and other tribes; also from the verbal relations of early Californians. (Jepson 1910)
(Cooper 1922, p. 80)
The Rainfall to Groundwater 4th blog post, Think Outside the Basin, notes Henry Lewis’ 1973 “Patterns of Indian burning in California: ecology and ethnohistory”, reprinted in 1993, which particularly focused on the ramifications of aboriginal land management through burning on the Sierra Nevada and its foothills. Jon Keeley (2002), hypothesized specifically that,
Native American burning in the coastal ranges of central and southern California subsidized natural lightning ignitions to the extent that landscape patterns of grassland and open shrubland were significantly increased. (Keeley 2002)
Citing Jepson’s (1923) observation of the “singular spacing” of valley oak trees and touching on other early observations was Randall Rossi’s (1980) overview of cultural impacts on oak woodlands including the following,
Fire was used to drive game, aid in collecting food, and make clearings for growing tobacco (Kroeber 1925). Any such fire could kill oak seedlings, but light ground fires would not harm established trees. Captain Belcher observed on the Sacramento River in 1837 that during the dry season the natives burned the annual growth, “and probably by such means destroy many oak plantations which otherwise would flourish” (Belcher 1969, p.48). Hinds, a botanist on Belcher’s expedition reported Sacramento Valley natives’ practice of lighting their fires at the bases of valley oaks. He continued, “and as they naturally select the largest, it was really a sorrowful sight to behold numbers of the finest trees prematurely and wantonly destroyed” (Hinds 1844, p. 3). From this brief description the death of the trees must be interpreted as accidental, since they represented a perennial food resource.
Verna noted in blog post 4, “Think Outside the Basin” how Kat Anderson’s (2005) map showing the “regional food complex” organized around chia (Salvia columbariae) encompassed most of central and southern California, along with some northern territories, noting that while the species does not require fire to germinate, it is adapted to disturbance, such as burning would most easily cause. Alas, in her haste to draft that post she neglected to consult her own dissertation, which cited chia as among the species whose seed germination is readily induced by smoke (Keeley and Fotheringham 1998). This is even further evidence that aboriginal burning altered landscapes throughout much of California. However, comparing the Calflora distribution maps (consulted June 2018) for chia, with that for thistle sage (Salvia carduacea) one might think the latter may have been of equal or greater importance in the southern San Joaquin Valley, given its apparent somewhat greater frequency there., as pointed out by Wester (1981), quoting John Muir (1894), wherein Muir referred to the latter species as “king of the mints”.
Back on the coast, Father Juan Crespí noted at numerous points in his journal of the first overland expedition from Baja into Alta California, led by Spanish Captain Gaspar de Portolá and beginning March 1, 1769 (Crespí 2001), the lands recently burned off by the “heathens”.
Anderson (2007) enumerates the specific locations where Crespí notes evidence of recent burning. While not a product of a systematic search, Verna’s observations were that, despite Crespí’s numerous mentions of burned-over lands on the journey northward, he generally notes distaste for the destructive and seemingly irrational burning pattern, and does not indicate a rationale for this disturbing activity until October 30, 1769, in what is now San Mateo County, where he finally mentions it in context.
Close to the shore, there ran on some tablelands and rolling knolls with very good soil and very good grass, though the latter all burnt, since the heathens burn it all off in order for a better yield of the grass seeds they eat. [Crespí (2001) section 237, p. 567]
So fixed in his European mindset, it apparently took Fray Crespí’ from early July to late October to make this connection, and then only after the natives had essentially rescued the expedition from starvation and helped orient the European wanderers who had, weeks before, passed by the Monterey harbor they were seeking without recognizing it, and were by then becoming worn down from the stresses of their mission as they came to that realization (Crespí 2001). No doubt the nourishing “black pies” made from the seeds of the indigenous “grasses” the natives provided them in the vicinity of Purissima Creek, just as “the soldiers’ pease gave out”, enhanced the party’s esteem for the people, who at that point were noticeably no longer referred to as “heathens” in the journal, despite their nakedness [Crespí (2001) section 232, p. 583].
Note that the black color suggests that chia, not a grass, was likely prominent in the ingredients of these pies, but journalists up through fairly recent times have used the term “grass” to loosely refer to all the species comprising rangelands.
The Keeley (2002) paper is freely available online and anyone interested is encouraged to download and review it. While Verna tends to agree with almost everything Keeley has ever published, the one exception is the paragraph of the 2002 piece on Native American impacts titled, “Increase water resources” [as a rationale for Native American burning]. Alas, here Keeley seems to have swallowed whole the “water yield” paradigm discussed on the Water Yield vs Baseflow Augmentation page. Verna doesn’t entirely blame him, given his extensive other contributions to plant and fire ecology that come near but miss full interdisciplinarity, but she is willing to wager she has devoted many years more consideration and literature review to that topic than Keeley had when he wrote that paragraph.
Native Shrub “Encroachment”/ “Invasion” on/of Nonnative Annual Grasslands in California
Like 99.9% his work, Verna wholly agrees with and is grateful for Keeley’s (2005) “Fire history of the San Francisco East Bay region and implications for landscape patterns” because it surely took someone of his stature and notoriety to (finally) debunk McBride and Heady’s (1968) “Invasion of grassland by Baccharis pilularis DC.” For you non-botanists out there, that’s coyote brush, a species native to California’s Coast Ranges and, moreover, among the most excellent of slope stabilizers. So all those range managers who sought to eliminate it, egged on erroneously by that highly biased grass-centric perspective, exacerbated unmeasured impacts on soil erosion, water quality and water quantity, as emphasized on this site. Verna is well aware that elimination of coyote brush is still considered a virtuous task, as in 2015, at the Central Coast Rangeland Coalition meeting in Hollister, she heard an otherwise quite savvy and articulate range manager describe how she’d ingeniously tried painting the stuff with molasses to get the cattle to eat it, though that was a bit much for general practice.
There’s the problem – range management is the most grass-centric profession there is, despite that there are alternatives that just might better serve California range management than exotic annual grasses, especially since some of them actually compromise forage objectives, as well as any hope of year-round grazing opportunities. Finding that woman’s style and her overall approach quite appealing, Verna sent her electronic versions of the Criollo cattle information and links after that meeting but received no response from her, which is basically the case for seemingly everyone she’s attempted to share the Rainfall to Groundwater approach with to date. Yet she knows she’s not wrong on this, so she presses on . . .
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To emphasize just how biased this “shrub encroachment/ invasion” paradigm has been, just consider the absurdity of native species “invading” lands that were previously invaded by exotic species.
Franco Folini from San Francisco, USA, Two Coyote bushes blooming (Baccharis pilularis) (4077218374), CC BY-SA 2.0
While it’s a shame it took regulation of endangered animal species to foster restoration of coastal sage scrub in southern California, that’s exactly what was needed and those restoration efforts over the past three decades serve as models for the rest of the state. Most recent is the welcome news of “Coyote brush as facilitator of native California plant recovery in the Santa Monica Mountains” (Brennan and colleagues 2018). From the abstract:
. . . This study investigates the long-term consequences of coyote brush invasion in a type-converted landscape of southern California. Stands of expanding coyote brush were transected to identify species composition along a spatial and temporal continuum. Results show that, following initial invasion, non-native species are gradually replaced by, not only coyote brush, but also several other noteworthy native species. This study finds that over the 37 yr timeframe, exotic grasses gradually decline while native plant cover increases in landscapes invaded by coyote brush. We conclude that in the Santa Monica Mountain areas studied, coyote brush invasion of type-converted landscapes leads to increased native plant diversity that includes native grasses and a variety of shrubs. (Brennan and colleagues 2018)
While Verna believes they should have put quotation marks around the word “invasion/ invaded”, given that coyote brush is merely reclaiming its former territory there, rather than “invading”, this work is gratefully welcomed as an example to other parts of the state also currently dominated with nonnative annual grasses. There are reasons why coyote brush serves as restoration facilitator and Verna hopes to share such insights with those who opt to enroll in her proposed courses, but first we need to shake y’all out of your existing, outdated paradigms that stand in the way of recovering watershed functions that would better serve us all.
Other remnant scrub species Verna has observed amidst otherwise annual grasslands/ oak savanna in the southeast San Francisco Bay area are worth mentioning here. Readily memorable from 2015 fieldwork in the Mount Hamilton Range at about 2000 ft / 610 m elevation, east of San Jose, east/ upslope from Alum Rock Park, are California sagebrush (Artemisia californica), California buckwheat (Eriogonum fasciculatum) and sticky monkeyflower (Mimulus aurantiacus var. aurantiacus) seen clinging to isolated, usually steep, pockets within a matrix of nonnative annual grasslands among isolated valley oaks, wherein stands of purple needlegrass (Stipa pulchra) reigned on serpentenized sloping ridgelines, with much smaller stands of oniongrass (Melica sp.) hanging on amid moderate grazing on private lands. These shrub species could hardly be viewed as “invading”, for they were quite clearly just managing to hang on to their tenuous footholds amidst the anthropogenic landscape. On these inland slopes they appeared as “ghostly” disturbance-adapted remnants of scrub associations still more or less intact throughout the Santa Cruz Mountain Range on the west side of Silicon Valley and southward. But they serve as clues to what might have been prior to at least 160 years, to perhaps many centuries of human disturbance there.
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John Rusk from Berkeley, CA, United States of America, H20140522-2442—Mimulus aurantiacus var grandiflorus—RPBG (14115593547), CC BY 2.0
More Jon Keeley on Fire Impacts to Vegetation and Alien Species Interactions
Keeley extended his insights on the broader topic of fire impacts to a broader geographic area and perhaps broader audience as well with “Fire management impacts on invasive plants in the western United States”, published in Conservation Biology, 2006. Keeley discusses here how prescription burning of ponderosa pine forests conducted for two decades in the Cedar Grove section of Kings Canyon National Park, southern Sierra Nevada, that was intended to “return a quasi-natural fire cycle for the resource benefit of these forests” was voluntarily halted in 1998
because of the recognition that associated with prescription burning was an explosion of cheatgrass (Bromus tectorum L.) in the burned forests (Caprio et al. 1999). (Keeley 2006)
Keeley points out that the very same problem has been found in sage scrublands of the intermountain west, where prescription burning has been used to “manage” what were considered “unnaturally dense scrub ”
In California chaparral, prescription burning is primarily justified on the basis of fire-hazard reduction, whereas in the Intermountain West sagebrush, the primary justification is benefit to ecosystem resources. The most commonly cited resource benefits are improved rangeland for wildlife (Beardall & Sylvester 1976; Holechek 1981) or livestock (Pechanec 1944; Sapsis & Kaufmann 1991). Other justifications include returning these ecosystems to their historical structure, which is considered by some to have been a landscape of more open sagebrush steppe vegetation. Indeed, rangeland literature commonly refers to the unnaturally dense stands of sagebrush in need of prescription burning (Blaisdell et al. 1982; Miller et al. 1994). In light of the massive cheatgrass invasion across much of this landscape (Mack 1981), coupled with the potential for burning to favor cheatgrass expansion (Harnis & Murray 1973; Knapp 1997; Young & Allen 1997), there is need for a closer examination of prescription burning in these Intermountain West ecosystems.
Prescription burning in sagebrush ecosystems is a highly effective method of improving rangelands for livestock grazing. The dominant shrub, Artemisia tridentata Nutt., is immediately replaced by more palatable herbaceous plants and recovers slowly over a period of decades (Stewart & Young 1939; Pechanec 1944; Ralphs & Busby 1979). On the other hand, prescription burning for enhancement of wildlife habitat appears to be justifiable in very few cases, and generally the loss of sagebrush following burning represents important habitat loss (Miller & Eddleman 2001; Welch & Criddle 2003). Restoring historical fire regimes is perhaps the weakest justification for prescription burning because many lines of evidence suggest fire-rotation intervals are currently at the low end of the historical range of variability (Menakis et al. 2003). . . .”
Note that “improving game habitat” was also among the rationales for converting California chaparral to grassland in USDA Forest Service Agriculture Handbook 328 (Bentley 1967).
Keeley goes on to reiterate the Native American burning of shrublands to favor herbaceous species and how that set the stage for the invasion of such lands by the invasive annual grasses introduced by Europeans.
By the late nineteenth century rangelands were in short supply, widespread burning expanded the grazing lands, and the coastal analogues of cheatgrass, specifically Bromus madritensis L., B. hordeaceous L., and B. diandrus Roth., and forbs such as Erodium cicutarium (L.) L’Her., rapidly expanded to fill the void created by removing natural shrub dominants (Keeley 1990, 2001, 2004b).
He notes how such burning for range improvement had been unregulated until the mid-20th century, but again, that territory is covered on this site by Verna’s 6th blog post, Ball and Chain & Other Links, so please check that out for more on California state policy that promoted removal of not only shrubs, but even oaks and other tree species in the name of “range improvement”.
At this point it seems appropriate to briefly interject with additional comment on Holstein’s (2011) contribution to Fremontia, specifically his emphasis on Burcham’s (1957) map, with herbaceous “California prairie” highlighted. While Verna generally finds Burcham’s report a fine, exemplary and informative piece of scholarship, Burcham essentially accepted rangelands as they were recognized during his time. To his credit he at least considered, but then discounted the potential prehistorical impacts of aboriginal burning in shaping extant vegetation patterns, so his map hardly counts as the final authority on “California’s pristine vegetation” (Holstein 2011) prior to human disturbance, as Holstein suggests there.
Although the hypothesis that frequent indigenous burning contributed to the vulnerability of California grassland to the initial invasions cannot be tested, it also cannot be discounted since it is now known that many nonnative annual species can tolerate or increase with grassland fires. Thus, it is reasonable to assume that the common occurrence of “grassland” fires in the 1700s and early to mid 1800s contributed to the rapid spread of some nonnative grassland species.
(Keeley and colleagues 2011)
Noxious Weeds as Side Effect of the Grassy Rangelands Paradigm
Keeley (2006) offers an easily understood “Moel of fire and alien species interactions in California chaparral” in his Figure 3, highlighting the interactions responsible for California’s expansive nonnative annual grasslands. Since it’s freely available online, please do check that out! He discusses the problems caused by fuel breaks, then “Prescription Burning to Target Noxious Aliens” which gets into the final points we want to make here.
One example widely cited in recent alien plant review articles as a demonstration of such success is the application of spring burning in the control of yellow starthistle (Centaurea solstitialis L.). . . .
Confidence in prescribed burning treatment as a control for this species is based on the results of annual burning for 3 consecutive years in very dense stands that demonstrated 90–100% reduction in starthistle (DiTomaso et al. 1999; Odion et al. 2004a). Burn plans written by agencies undertaking prescribed burns in annual grasslands often use this as one of their primary goals (e.g., East Bay Regional Parks, http://www.ebparks.org/fire/rxfire). This species, however, like many aliens, has a relatively long-lived seed bank (Callihan et al. 1993), and longerterm study shows that this thistle rapidly reestablishes once burning is halted (Fig. 6). . . .
This gets us into one of the final points we wish to emphasize here. While late 20th century land managers often conceived of prescription burning as “modern” acceptance of natural fire regimes (in contrast with the early 20th century agenda of attempting to suppress all fires), the practice of burning as a land management tool is anything but modern and in our increasingly globalized world it tends to favor expansion of invasive exotic species populations that are adapted to human disturbances. As noted in blog post 4, there is little doubt among archaeologists that intentional human ignition of range fires has been a landscape transforming pattern around the globe for the past 10,000+ years (Redman 1999).
We must also question the continuing, ongoing expansion of other noxious species like medusa head (Elymus caput-medusae), which like yellow starthistle, compromises the viability of annual rangelands for livestock forage. In the case of medusahead the problem is its unpalatable foliage of high silica (essentially glass) content (Bovey and colleagues 1961) that also leaves behind a deep thatch that is slow to decompose and is thus impenetrable by the seeds of desirable forage species, although not to its own seeds.
Verna hadn’t studied this species in any depth but was aware of its problematic invasion of rangelands noted in mid-20th century literature, for example Burcham (1957). So when she had the chance to query experts working to stem its ongoing expansion, on the 2017 California Rangeland Conservation Coalition Summit field trip, she had to ask (paraphrase), “Since this was a recognized problem back in the 1950s, are we not learning anything?” That brought some chuckles but, in truth, we seem to be learning lots about medusa head, just not how to eliminate it from annual rangelands.
For example, a June 2018 google Scholar search using the alternate botanical name (Taeniatherum caput–medusae), which yielded more results than the original/ current genus name Elymus, turned up about 2,280 results. Narrowing that down to those since 2014 produced about 533 results; since 2017 about 151 results, and January through June 2018 about 55 results. An ongoing research effort, indeed!
The thing is, in a 1955 California Agriculture article about rangeland weeds, Jack Major wrote,
About 1903, medusa head had just invaded California from Oregon. In 1955 it covers great areas – in Siskiyou, Shasta, Tehama, Glenn, Colusa, Lake, Humboldt, Mendocino and Solano counties – with a dense blanket of useless, inedible, wirelike grass . . . Furthermore, medusa head has migrated south as far as the mountains of Santa Barbara county.
It’s not clear what Major’s (1955) source was but Young (1992) notes it was collected “near Los Gatos, California in 1908 by Charles Hitchcock (Jepson 1923)”. Young notes the first U. S. collection as 1887 in Roseburg, OR, another near Steptoe Butte, eastern WA in 1901. The geographic spread of those early collections strongly suggest that human and/or human-managed livestock were the dispersal agents, as was concluded in a recent review (Nafus and Davies. 2014).
The cover photo of Activity in Range Improvement: CDF Annual Report [California Division of Forestry (CDF) 1962] is an image of a medusa head inflorescence and that report documents that the species had by then spread to Fresno County. The report states (p 16):
Medusa-head was reported found in Fresno County for the first time in 1961. The medusa-head infestation in Merced and Madera counties appears to be static at about 18,500 acres.
A June 2018 query of the Calflora database indicates its distribution as throughout the San Francisco Bay area southward along the coast through Ventura and extreme north and west Los Angeles, as well as San Diego Counties, and southward along the Sierra foothills and Central Valley through Tulare County. So the species has been a California rangeland pest for well over a century now and its distribution has only been expanding, despite all the research devoted to it. Plenty of research topics for grad students, if that is an objective.
So perhaps a better phrasing of Verna’s 2017 question is more like, “What haven’t we learned through all this dedicated research?” Might it be that we haven’t learned that managing these lands with grasslands as the goal is the wrong approach? Verna agrees wholeheartedly with the following comment by Jon Keeley:
Sustainable control of these aggressive weeds is most likely going to occur only when natural, intact ecosystems are restored. In the case of yellow starthistle, it invades annual grasslands that owe their origin to disturbance, either displacement of native perennial grassland or type conversion of shrublands and woodlands (Huenneke 1989; Keeley 1990; Hamilton 1997).
Biogeophysical attributes described below for sagebrush scrublands of the Intermountain west likely have analogs in different forms of California scrublands and may affect their relative resistance to invasion of exotic species.
Wind erosion products accumulate under the shrub canopies and, coupled with organic matter from leaffall, build mounds under the shrubs while miniplayas develop in the interspaces. Eckert et al. (1989) have described and experimented with the seedbed of these mound interspace situations, particularly the vesicular crust that forms in the interspaces and limits establishment of perennial grass seedlings.
A side note from Major (1955) is that native coyote brush is included among “other troublesome weeds of California rangelands:” with respect to the San francisco Bay area, as is true for chamise (Adenostoma fasciculatum) as a widespread “weed”, also manzanitas (Arctostaphylos species) as widespread with rangeland impacts varying by species. So it’s clear that McBride and Heady (1968) were not the first with such a viewpoint on native shrubs in rangelands. Again, see blog post 6, Ball and Chain & Other Links.
If we stop trying to perpetuate grasslands over vast areas of the state that were likely not grasslands prior to anthropogenic impacts, we may finally get a grip on noxious annual rangeland weeds. Moreover, we can doubtless restore watershed functions supporting groundwater recharge if we restore native woody plant species to these lands, reversing the long-standing pattern of woody species removal that has prevailed in historical and even prehistorical times. Does this mean these lands can’t continue to serve as rangelands? Emphatically NO! We just need to get beyond the idea that rangelands should only serve cattle stock bred in much wetter climates to eat solely grasses. Some suggestions are offered on Criollo Cattle? and Livestock Appellations for California?
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