C. DAVID BERTELSEN Adjunct Associate Research Scientist, UA SNRE Associated Researcher, UA Herbarium

PRESENTED AT THE R.I.S.E. SYMPOSIUM OCTOBER 26, 2019 5 ≈1100 ac (0.6% of the entire range)

I’ve explored only ≈ 80 ac on foot, Mt. Kimball Trail (white line) including the trail, 3.5 miles of the 4158 ft elevation gain canyon bottom, and several side drainages. 4 First hiked to Mt. Kimball in 1981 Data collection began in 1984 along five 1-mile long transects 3

SANTA 2 CATALINA MOUNTAINS

1 X CHECKLIST FOR DATA COLLECTION

1711 hikes to the peak (over 17,350 miles including X shorter hikes)

181,056 flowering records 82,573 vertebrate records 263,629 total records Cool Season (November-March)

Tradescantia occidentalis SW CLIMATE: VARIABILITY AND DROUGHT

Cool Season (November-March)

The current drought is now the 4th worst

megadroughtWarm Season (May in 1200-October) years

SOURCE: Woodhouse et al. (2010) A 1,200-year perspective of 21st century drought in southwestern North American. PNAS 107:21283-21288. More frequent and prolonged drought is symptomatic of climate change Tradescantia occidentalis

5 Since 1994, average annual temperatures in the study area 4 3 have been above the 89-year average except in 1998 2 1 0 -1 -2

-3 TEMPERATURE ANOMALIES, 1984-2018 (0 = 1930-2018 AVERAGE)

2012 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2013 2014 2015 2016 2017 2018

15 In the last 25 years, annual precipitation has 10 been above the 89-year average in only 7 years

5

0

-5

-10 PRECIPITATION ANOMALIES, 1984-2018 (0 = 1930-2018 AVERAGE)

1984 2014 2015 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2016 2017 2018 Climate data source: www.prism.oregonstate.edu

15 Since October 1994 precipitation has been significantly above the 89-year averages in only 6 cool seasons and 6

10 warm seasons.

5

0

-5

-10

99-00 09-10 83-84 84-85 85-86 86-87 87-88 88-89 89-90 90-91 91-92 92-93 93-94 94-95 95-96 96-97 97-98 98-99 00-01 01-02 02-03 03-04 04-05 05-06 06-07 07-08 08-09 10-11 11-12 12-13 13-14 14-15 15-16 16-17 17-18 18-19

Funastrum heterophyllum Responses at the species level, not at the community level

Phenology changes (i.e., earlier or later onset of flowering, changes in length of growing seasons);

Changes in abundance (i.e., increases, decreases, and disappearances);

Changes in composition (i.e., in growth forms and non-native species); and

Shifts, extensions, and contractions of species ranges to higher elevations/latitudes. Funastrum heterophyllum Carnegiea gigantea Carnegiea gigantea Castilleja tenuiflora “Although species extinctions are of great evolutionary importance,

and will generally cause greater impacts on ecosystem function.” Dirzo, R.D., H.S. Young, M. Galetti, G. Caballos, N.J.B. Isaac, and B. Collen (2018) Defaunation in the Anthropocene. Science 345: 401-406

“We conclude that any mechanism of global change that selectively destroys small habitat patches will lead to imminent extinctions in most discrete metacommunities.” Deane, D.C. and F. He (2018) Loss of the smallest patches will reduce species diversity in most discrete habitat networks. Global Change Biology 24:5802-5814 Castilleja tenuiflora Today I will describe some of the cumulative changes—which I think are fundamental and transforming—that have occurred in less than 20 years. These changes involve both sudden and gradual change.

Sudden change is hard to miss. Gradual change, however, is difficult to detect. It’s hard to see what isn’t there—even if you have baseline data. Gradual change is usually unrecognized until cumulative effects result in crossing a threshold. Allium macropetalum black rattlesnake (juvenile)

Reticulate Gila Monster Arizona black rattlesnake (juvenile)

Reticulate Gila Monster Lupinus sparsiflorus parishii Hackelia ursina Stachys coccinea All of the flowers shown in this presentation are of species that have declined or disappeared since 2002.

Hesperidanthus Heuchera sanguinea linearifolius Circium arizonicum Agastache rupestris During the first 11 years of my study the only significant change I was aware of was the steady increase in the number of taxa I was seeing— likely because the 1970s were relatively dry and the 1980s, relatively wet. 90% of the current flora Lupinus sparsiflorus hadAbutilon been parishii identifiedHackelia by ursina1994. Stachys coccinea All of the flowers shown in this presentation are of species that have declined or disappeared since 2002. Relatively little change in the flora was seen in the next 7 years. When I first saw significant changes in vegetation in 2002, I began to consciously look for change, and the more I looked, the more I saw. Having an 18-year baseline certainly facilitated recognition ofHesperidanthus the impacts of on-going drought. Heuchera sanguinea linearifolius Circium arizonicum Agastache rupestris Graptopetalum rusbyi Because annuals tend to track climate fluctuations while perennials are better adapted to long-term climate variability, perennials are probably better indicators of climate-driven impacts to ecosystems

There has been little or no recruitment of perennial species in decline. Graptopetalum rusbyi

DESERT SCRUB ≈ 2O.9% OF TOTAL AREA, 41% OF FLORA (251 TAXA) At all elevations, annuals are most susceptible to decreasing precipitation. But in desert scrub, annuals make up 44% of the taxa. Since 2002, native spring annuals have not rebounded in years with good winter precipitation resulting in considerably more bare ground. Has there been a reduction in the seed banks? Non-native annuals continue to quickly respond to improved conditions. Carlowrightia arizonica • 185 have died, including 35 in 2002, 24 in 2011, and 7 so far this year. Most mortality has been on the west side of the canyon and usually occurs late May & June.

• Compass Barrel Cactus, once dominant, has been nearly replaced by a faster growing hybrid barrel (Compass x California Barrel). Nearly all mortality has been of Compass Barrel.

Carlowrightia arizonica Cylindropuntia versicolor • Most native grasses (e.g., Bush Muhly, Fescues, Fluff Grass, and the ternipes variety of Spidergrass) are nearly gone, but Lehmann Lovegrass, Natal Grass, Buffelgrass, Mediterranean Grass, and Soft Feather Pappusgrass (all invasive) have increased.

• Parry Penstemon, once common here, is now rare. The center of the population has shifted to Oak

Woodland, more than 1200 ft higher.Cylindropuntia versicolor

Xeroriparian systems, characterized by intermittent streams, merit a lot more attention because of their high biodiversity and the fact that they serve as refugia in times of drought. Such systems are likely to be the future state of the lush riparian areas we love so much. Commelina erecta • Most native species typical of riparian areas such as Flatsedges, Rushes, Cupgrasses, Hummingbird Trumpet, Yellow Monkey Flower, and Hooker Evening Primrose have sharply declined or disappeared.

• The number of Engelmann x Tulip Pricklypear hybrids has increased. Commelina erecta Passiflora mexicana • Most non-native annual grasses such as Wild Oats, Wild Barley, and Rabbitfoot Grass have declined, but Buffelgrass, Annual Bluegrass, Fountain Grass, and invasive Pappusgrass have increased greatly.

• The highly invasive African Sumac tree began to invade the canyon bottom in 2006. It’s still being sold in nurseries and is well established along the Rillito. These canyon drainages provide a direct link between urban, suburban, and wildland areas. Passiflora mexicana

SCRUB GRASSLAND ≈7.8% OF TOTAL AREA, 49.8% OF FLORA (305 TAXA) Scrub Grassland is limited here, but until recently it has been dominated by native grasses. 44 native grass taxa have been observed on this slope. This is changing, however, and this association will be likely be transformed into an “Africanized” grassland dominated by non- natives, particularly Lehmann Lovegrass and invasive Pappusgrass. Fire would likely hasten this change. Cnidoscolus angustidens • As many native grasses (e.g., Longtongue Muhly, Cotta grass, Green Spangletop, and the ternipes variety of Spidergrass) have declined, Lehmann Lovegrass, invasive Pappusgrass, and Stink Grass have increased exponentially.

• In 2015-2017, meter-high invasive Pappusgrass (an annual) was so dense on one slope that it crowded out nearly all native grasses, including Bull Grass, Side-Oats Grama, Hairy Grama, Cane Beardgrass, and Arizona Cottontop (all perennials). • ` Cnidoscolus angustidens Dipterostemon capitatus subsp. pauciflorus • In the summers of 2013 and 2014, 58 Staghorn Chollas and many Engelmann Pricklypears died; but the Englemann x Tulip Pricklypear and the Barrel Cactus hybrids have increased.

• Wavy Cloak Fern has replaced Scaly Cloak Fern.

Dipterostemon capitatus subsp. pauciflorus

OAK WOODLAND ≈32.9 % OF TOTAL AREA, 49.3 % OF FLORA (303 TAXA) If current trends continue, this will likely become Scrub Grassland as trees and large shrubs continue to die. Lehmann Lovegrass remains the dominant grass species in the area burned in 2015. In the burn area, more native species have reappeared in Oak Woodland than in Oak- pine Woodland, but native diversity has declined sharply in both areas. Fire would likely hasten the conversion. Oxalis albicans • Mohave Penstemon and Wild Cotton are the only native species that clearly benefited from the fire, at least from what I’ve seen so far.

• Many herbaceous perennial, subshrub, and shrub species have declined.

• All reproductive Palmer agave were gone by 2006, largely due to pocket gopher herbivory. Oxalis albicans Talinum aurantiacum • The gentilis variety of Spidergrass is the only native grass that has increased significantly in OW since 2002. But Lehmann Lovegrass, Stink Grass, Red Brome, and invasive Pappusgrass have increased much more and produce far more biomass.

• Pancake Pricklypear is now rare, due to herbivory by pocket gophers and fire, but the Engelmann x

Tulip Pricklypear hybrid is moving intoTalinum OW. aurantiacum

OAK-PINE WOODLAND ≈27.5% OF TOTAL AREA, 52.6 % OF FLORA (324 TAXA)

Because of the greater density of trees and shrubs here, the considerable change occurring is harder to see. If these changes continue and intensify, however, this area will likely evolve into a novel community dominated by shrubs and scattered trees. Widespread fire would hasten the change. Comandra umbellate subsp. pallida • After the 2015 fire, the area burned in Oak-pine Woodland was densely covered by Lehmann Lovegrass and invasive Pappusgrass (unknown in the area prior to the fire). Native species are slowly reappearing, except on ridgetops where Lehmann’s seems to have a firm foothold. I have seen no resprouting of Alligator Juniper or Sotol. • The fire was described by experts as “moderate” and “beneficial,” based on existing standards and guidelines. From what I’ve seen, the desirability of prescribed fire needs to be reassessed in light of invasive species, climate change, and lack of resources necessary to mitigate negative effects. Comandra umbellate subsp. pallida Mammillaria viridiflora • A few scattered Emory Oaks and Silverleaf Oaks died in 2010. Four Emory Oaks died in June 2019.

• Catclaw mimosa has increased dramatically, now forming large stands between 5600-6000 feet and colonizing areas opened up by dead oaks. This portends a major structural change.Mammillaria viridiflora Arctostaphylos pungens • Most Narrowleaf Hoptrees, including all large individuals, have died.

• Several native perennial grasses (e.g., Bluestems, Spangletops, Plains Lovegrass, and Crinkle-awn) are now uncommon.

Arctostaphylos pungens Echinocereus coccineus • Red Brome nearly disappeared as the drought deepened but persisted at 6200 feet in OPW.

• Engelmann and Pancake Pricklypears have declined but likely Mohave x Englemann and Engelmann x Pancake hybrids have increased. Could climatic conditions be promoting hybridization or hybrid success, (e.g. via a change in pollinators)?

Echinocereus coccineus Euphorbia palmeri subsp. subpubens • Only one Palmer spurge survived after 1996. Unlike most perennials, it flowered only in 1998, 2001, and 2005 before dying.

• Six-weeks Three-awn Grass is the only native annual that appears to be expanding its range in the canyon. It is also the only annual that shifts its prime flowering season from spring to summer with increasing elevation. It seems to be replacing five native annual MuhlyEuphorbiaand Lovegrass palmeri subsp. species subpubens.

PINE FOREST ≈4.5% OF TOTAL AREA, 22.1% OF FLORA (135 TAXA)

I used a sunset photo here because I thought Pine Forest would likely be the first vegetative association to disappear—I anticipated it becoming Oak-pine Woodland. And then bark beetles began to kill pinyons. Without pinyons, Pine Forest may transform into Oak Woodland with scattered Junipers, and perhaps a relic Ponderosa or two. Sedum cockerellii • Last year, three trees died in May, another in August, and three in November. I have seen no sign of bark beetles and until last year no evidence of previous stress (yellowing or dropping needles).

• There has been a sharp decline in herbaceous perennials and both Fendler Bluegrass and Bulb Panic Grass. Lehman Lovegrass has increased.Sedum cockerellii Hedeoma hyssopifolia • The small population of Plains Pricklypear on top of Mt. Kimball increased both in distribution and in numbers from 2006-2010—until pocket gophers began to eat them. I can now find only 3 clumps.

• Groundsel is now common only on the peak. This was the first species to be decimated by pocket gophers as drought killed other food plants. Then they then moved on to century plants & pricklypears. A single species can wreak havoc! Hedeoma hyssopifolia

Even if the drought ended tomorrow, cumulative changes that have occurred will probably not reverse themselves if temperatures continue to increase, storms become more intense, and precipitation becomes more variable.

Tipping points have likely been passed.

From what I’ve seen, the three greatest impacts of climate change in this area will be a sharp reduction in the moisture available to plants; the exponential increase in invasive, non-native species; and

the increased frequency of fire.

I don’t think most native species will be able to adapt quickly enough.

If climate change is the underlying driver of the changes I’m seeing, rather than cyclical drought—and this seems highly probable— significant changes will accelerate, and very different landscapes will emerge. Hyperbole? Consider: Tree mortality in California’s Sierra Nevadas since 2014 has reached 147 million trees; 18 million died last year alone. The lead author of a study of tree recruitment & survival in Yellowstone NP predicts the park will become a grassland by mid century.

QUESTIONS? [email protected]

With particular thanks to UA Herbarium staff, the late John & Charlotte Reeder, Richard Felger, Jim Verrier, Jillian Cowles, Mike & Theresa Crimmins, and Jeff Belmat