"Mapping and Monitoring Populations of Turk’s Head Cactus and Pima Pineapple Cactus in Southern Arizona: Emergent Perspectives and a Growing Alarm about their Future"
Presented by Robert J. Schmalzel
I began setting up permanent plots and monitoring both Turk’s Head (TH) and Pima Pineapple (PP) cacti in 1998 with small grants from Arizona Dept of Agriculture and Fish and Wildlife Foundation. In 2018 through 2021 I focused on a dense population of Pima Pineapple Cactus on the Buenos Aires Natl Wildlife Refuge (BANWR). In addition I have seeded PP in several areas around 2000. Emergent perspectives include:
• Seed to first flowering in the wild requires about 45 years for TH, about 20 years for PP. Without an awareness of how old PP plants are, researchers on BANWR have identified dense stands of mesquite and Lehmann’s lovegrass as “habitat” for PP; it is more likely that these PPare vestiges of a plant community 50 years ago that permitted the spread of PP seeds into the area.
• TH in 1998 occurred in high densities on Horquilla Formation on both Waterman and Vekol mountains, about 1 plant per 1-meter². Seedlings established on Horquilla, independent of parents. TH on the alluvium around the Waterman Mountain established primarily within the spine apron of young adult plants, an example of parental care, recognized for other plant species in tropical mountains. Human theft of TH on the alluvium has been ongoing since 1998; theft of young adults removes the microsites for seedling establishment.
• About 95% of the dense population of TH on the Waterman Mountains has been killed/eaten since 1998. Desert bighorn sheep are responsible for this unsustainable mortality. Several features of sheep feeding on TH will be described. TH in Arizona is federally listed. Desert bighorn sheep are not. Yet, priority is given by Arizona Game and Fish Dept. (AGFD) and Bureau of Land Management to safe-guarding the sheep; no consideration has been given to conserving TH on this mountain. AGFD built a rain cachement for sheep adjacent to the dense TH patches. Today the few remaining TH on Horquilla grow beneath ocotillo or bedrock outcrops where sheep cannot feed on them. John Scheuring has worked on removing invasive grass and ‘restoration’ of the landing strip, north side of the Waterman Mountains. Restoration of the landing strip has involved chisel plowing, seeding with native plants and adding many tons of branches (as termite food). These actions will create an area suitable for pocket gophers (Thomomys bottae). Gophers sever the roots of TH at the base of the plant. The landing strip had been built on alluvium deposited over 1 million years ago; it is naturally consolidated/indurated and should not have been plowed. Plowing, seeding and addition of brush for termites set up conditions for colonization by Thomomys, precluding TH from the landing strip.
• Similarly, Tom Ellis (BANWR manager in the 1990s) chisel plowed a total of about 6-miles² on the Refuge in order to remove snakeweed (Gutierrezia spp.) stands. The plowing occurred over several years at a number of sites and resulted in the rapid establishment of dense stands of Lehmann’s lovegrass. PP occurred in the coppice mounds around snakeweed plants. Chisel plowing removed PP from this large area, as well as displacing tortoises, gila monsters, and nest sites of Cassin’s sparrows and Lesser Nighthawks, all present in the original snakeweed stands, and absent today. A number of monsoon forbs grew in the snakeweed communities that were eaten by pronghorn. These forbs no longer exist in the Lehmann’s lovegrass stands.
• The Forest Service around 1995 built two cattle exclosures along Duquesne Road, east of Nogales, in order to protect the densest patches of PP. The Duquesne Road PP population has been monitored annually by the Sierra Vista District of Coronado National Forest for the last nearly 30 years. During that time, the population has decreased from about 150 to 1. Forest Service now mandates the rancher not exceed 35 or 40% utilization of the grass. In fact, the 150 PP were present in the area because of a high level of grass utilization (estimate > 80%). Bare ridgelines near Duquesne Road provided safe areas for antelope jackrabbits to sit, defecate and disperse PP seeds into the areas. Currently the grass is too dense within and outside the exclosures for antelope jackrabbits to use.
• On BANWR as well as a number of sites in the Santa Cruz and in the Altar valleys, I set up camera traps on fruiting PP. I recorded with videos at least 50 separate instances of antelope jackrabbits removing the fruits from PP. They chew the fruits briefly before swallowing. Many of the seeds emerge intact; of 170 seeds I recovered from jackrabbit dung (pellets), at least 70% germinated. In the Recovery Plan for PP, Fish and Wildlife Service includes a photo of a Harris Ground Squirrel with a PP fruit and list the birds and mammals that were photographed by their camera trap. The ground squirrel is a seed predator. Forest Service built rabbit cages around PP along Duquesne Roadca 1995. When I visited the cages with Forest Service personnel, entire sets of fruits were still on the PP plants from the preceding year. I asked the people about which animals were responsible for seed dispersal. They did not know and were not interested.
• Rabbit hemorrhagic disease Type 2 spread across the western USA in 2020, reaching Pima County in April, 2020. Antelope jackrabbits were abundant prior to the arrival of this virus. Antelope jackrabbit populations collapsed when the virus arrived. Four years later only about 1 to 2% of the original population exists. It is likely that PP is no longer effectively dispersed. I expect PP to decline or disappear within the next 20 years.
• Annual monitoring of patches of rare, sensitive or federally listed plants is viewed as a chore by federal and state agencies. Get in; get out. On several occasions John Anderson (BLM botanist retired)described how uninteresting monitoring of rare plants was. He would intone that ‘rare plants were losers, they used to be widespread but had lost out to more modern competitors, he should only stop at a historic patch, and record whether some individuals are still present, check the box present or absent, and drive away.’
• Monitoring plant populations provides a window into natural selection. Juvenile cacti and adult cacti that ‘shrink’ suffer almost no mortality; the shift to adults with elongating stems is accompanied by an abrupt increase in stem mortality for both TH and PP. This is very likely the case for many species of cacti in the tribe Cacteae in the Chihuahuan Desert. Why are so many of these adult ‘shrinkers’?
• Graduate degree programs at U of A, ASU and NAU do not challenge students in the environmental sciences to think critically and adaptively. The bulk of students that are hired afterwards to manage Federal and State lands are not/will not be up to the task of critically evaluating management decisions and their consequences. This is a crisis unfolding.
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