Cactus conservation and restoration of arid environments in Central Mexico

En route to attending the 4th meeting of the Ecological Restoration Alliance of Botanic Gardens Conservation International, in Xalapa, Veracruz, Mexico, James Aronson stopped off to visit Beatriz Maruri Aguilar, a recent Bascom Fellowship recipient who works as Scientific Research Coordinator at the Cadereyta Regional Botanic Garden, and her colleagues, Director Emiliano Sanchez Martinez, and Research assistants Hailen Ugalde de la Cruz and Hugo Altamirano Vázquez in Cadereyta de Montes, Queretaro, north of Mexico City. Beatriz and Hailen describe the Garden’s work conserving an endangered, endemic cactus, and an innovative restoration project.


Main entrance to Cadereyta Regional Botanic Garden

Cadereyta de Montes is close to the southern end of the Chihuahuan Desert, in the semiarid zone of Queretaro and Hidalgo. The place is relevant for biodiversity because of its number of endemic arid plants. However, today some habitats have been definitively altered and several special plants are on the brink of extinction.

One of those emblematic species, popular among succulent plant collectors around the world, is under severe threat to its survival. Worldwide growing successfully in cultivation, Mammillaria herrerae Werderm. is facing tough conditions and could eventually disappear from its original habitat. Scientists from the Cadereyta Regional Botanic Garden have done a survey which indicates that there are only a few hundred individuals remaining in the wild, that the species shows very low recruitment by seed, and that seedlings grow on rocky substrates beneath nurse plants.


Expedition day: James and Beatriz descend the slopes where Mammillaria herrerae lives. Photo by Hailen Ugalde de la Cruz.

Observing the remaining individuals is a shocking experience that moves to reflection.

They look small and fragile, but these geometric, almost spherical, plants are a beautiful example of the precision of nature, which gives each organism the characteristics it requires to survive in its natural habitat.


The beautiful Mammillaria herrerae Werderm., also known as “golf ball cactus” or “bolita de hilo” (small ball of thread). Photo by Beatriz Maruri Aguilar.

Densely covered with white spines and half-buried in the rock, Mammillaria herrerae hides its presence in the limestone soil. Its densely-distributed spines also help harvest fog at this elevation, where atmospheric moisture can condense. In an arid region like central Mexico, such adaptations provide species with strategies to reach the vital element.


A small group of Mammillaria herrerae struggle to persist on the steep slope. Photo by Hailen Ugalde de la Cruz.

Their permanence wouldn’t be menaced, but infrastructure development has reached them.


The pipes of the “Acueducto II” Hydraulic system climb more than 1200 meters to reach an elevated point from which it carries water by gravity to Queretaro City. Photo by Beatriz Maruri Aguilar.


In such a challenging environment, the construction of this infrastructure has severely damaged the landscape where Mammillaria herrerae lives. Photo by Beatriz Maruri Aguilar.


As the aqueduct was constructed over several years, several efforts were conducted to relocate bigger native plants. Photo by Hailen Ugalde de la Cruz.

Efforts will continue. The Cadereyta Regional Botanic Garden team will conduct a 2-year demographic study, study the floral biology of the species, and describe plant community biodiversity at the specific distribution points. Stock propagation at the Garden will continue. The path is being prepared to, one day, return these jewels to their place in their natural environment, and to protect them better in situ.


Hailen Ugalde (left), Hugo Altamirano (center), and Beatriz Maruri (right), the staff of the Cadereyta Regional Botanic Garden, visit a remnant population of Mammillaria herrerae . Photos by James Aronson (left) and Hailen Ugalde de la Cruz (right).


The landscape around M. herrerae’s natural habitat. The mountain in the background is the southern facies of the Sierra del Doctor, part of the Sierra Madre Oriental. Photo by Hailen Ugalde de la Cruz.


Some of the globose companions of Mammillaria herrerae Werderm. Left: Astrophytum ornatum (DC.) Britton & Rose; Right: Mammillaria parkinsonii Ehreb. Photos by Hailen Ugalde de la Cruz.

“An unusual model of assisted ecological restoration”

At first sight, the arid scenery of the surroundings of the small city of Cadereyta, in Queretaro, Central Mexico, could transport us to past times.


Panoramic view from Cadereyta de Montes, and the ancient flavor of the streets. Photos by José Belem Hernández Díaz.

However, this semi-urban and semi-rural zone combines the features of ancient Mexican villages and landscapes with the unmistakable signs of the transformation that progress usually brings.

The peripheral landscape of Cadereyta de Montes (14,000 inhabitants) is showing signs of transformation. The urban area is gradually displacing the agricultural parcels and the native flora, giving rise to an interface formed of irregular patches that combine new houses and small agricultural parcels. A third type of ground, neither agricultural nor urban, is also present. This type of land is isolated from wild and agricultural areas, and can degrade easily.


The polygon of the Cadereyta Regional Botanic Garden, highlighted in yellow, in the vicinity of Cadereyta de Montes. Map prepared by Beatriz Maruri Aguilar.

In additional to its formal collections and buildings, the Cadereyta Regional Botanical Garden maintains an area that exemplifies the conditions found in much of the surrounding semi-arid region. Xerophytic shrub-dominated matorral is the main vegetation type which is generally highly degraded by human activities over the last decades, and surviving remnants in good ecological condition are only found quite isolated from agricultural areas. The vegetation comprises an interesting assemblage of native species in the Asteraceae, Poaceae, Solanaceae, Verbenaceae, Euphorbiaceae, Cactaceae, Fabaceae and other families, many of which are struggling to survive within large patches of invasive grasses.


A view from the top: looking down at degraded land to be managed by the Botanic Garden. Photo by Hailen Ugalde de la Cruz.


Another view from the top: Hugo, Beatriz, and James observe the transformed landscape of Cadereyta de Montes from one of the Garden’s balconies. Photo by Hailen Ugalde de la Cruz.

In this area, the Botanic Garden is working on restoration models that will be of interest – and direct use – to local landowners. It is an unusual model of assisted ecological restoration, with an agroforestry approach. The core idea is that through the implementation and monitoring of native vegetation and economic plant mosaics, it should be possible to combine conservation of biodiversity, sustainable development for small farms, and ecological restoration of degraded lands.

The pilot project will have two different types of parcels for comparative and demonstration purposes. One type will be built following an ecological approach to restoration, using only native plant species; the other will have an agroforestry approach, combining a group of native species with some selected edible/useful species. The area of the plots where the two strategies will be implemented will be prepared by removing an invasive species of grass (Melinis repens Willd. (Zizka), or “pink grass”). The agroforestry model will also generate useful products, such as agave leaves, which are used in the region for several purposes including to make pulque – an ancient beverage made by the fermentation of the agave sap, highly popular in this region. This model will also include aromatic plants – such as the asters Matricaria chamomilla L. and Calendula officinalis L. and the mint Salvia sp., as well as other useful plants as the euphorb Jatropha dioica Sessé, “sangregado”, commonly used as an ingredient in shampoos and formulas against gray hair.  These human uses are valuable in areas like this, where some human populations are suffering from an elevated degree of marginalization. The Cadereyta Regional Botanical Garden has developed propagation protocols of native species, and part of the stock produced will be used in the model described.


Some of the stock of native species produced at the Cadereyta Regional Botanic Garden. Photos by Beatriz Maruri Aguilar (top) and Hugo Guadalupe Altamirano Vázquez (bottom).

At Cadereyta de Montes, some areas need a helping hand to keep the landscape in good shape. Other places hide extremely valuable living treasures that are currently struggling for survival. The Cadereyta Regional Botanic Garden is working every day to contribute to the conservation of the highly remarkable flora of the southern end of the Chihuahuan Desert, as well as to offer sustainable solutions for landscape use in a transforming environment. This way, the Garden intends to become an active participant for the achievement of Mexico’s goals for plant conservation.

The Desierto Central of Baja California: past, present, and future.

James and Thibaud Aronson, and Edouard Le Floc’h, are working on a book on lost and regained tree canopies and ecological restoration in desert and dryland regions of the Earth. Here is their second report from Baja California, Mexico in March 2015.

In our last posting, we described Guadalupe Island and the NGO “Group for Ecology and Island Conservation” or Grupo de Ecología y Conservación de Islas (GECI), which is doing fine restoration work on more than two dozen Mexican islands since 1995.

After spending a week on Guadalupe Island, with Luciana Luna and Julio Montoya of GECI, Luciana and Antonio Alcaraz accompanied us to cross the bumpy and still quite remote Central Desert, which includes 77,700 square kilometers (30,000 square miles) of some of the most beautiful desert in the world.

We crossed from El Rosario, on the Pacific coast, to Bahia de los Angeles on the coast of the Sea of Cortez, also known as the Gulf of California. This is the enchanted subtropical desert that Joseph Wood Krutch described so memorably in The Forgotten Peninsula based on his visits to the region in the late 1950s, when “Baja” was still incredibly difficult to visit and almost no scientific work had been undertaken.


Luciana Luna and Antonio Ortiz Alcaraz of GECI, the Grupo de Ecología y Conservación de Islas.

Desert landscape between Cataviña and Punta Prieta, Baja California.

Desert landscape between Cataviña and Punta Prieta, Baja California.

Our focus of course is on trees, of all sizes and shapes, including the “queer, queerer and queerest” as J. W. Krutch called them, including the Boojum tree, known in Spanish as cirio. We are also keenly interested in the animals that use them, including birds, bats, and invertebrates.


A 6-meter tall Boojum (Fouquieria columnaris) providing a nesting site for a red-tailed hawk (Buteo jamaicensis), at the gateway to the Valle de los Cirios National Park, Baja California.

Gila woodpecker (Melanerpes uropygialis) on a Cardón, Pachycereus pringlei. Cataviña, Baja California.

Gila woodpecker (Melanerpes uropygialis) on a Cardón, Pachycereus pringlei. Cataviña, Baja California.

The spectacular desert palm trees merit our full attention as well, of course, wherever they still occur in washes, or arroyos.

Mexican Fan palm (Washingtonia robusta) and the Blue fan palm (Brahea armata) in an arroyo at the entrance of Cataviña, Baja California.

Mexican fan palm (Washingtonia robusta) and the blue fan palm (Brahea armata) in an arroyo at the entrance of Cataviña, Baja California.

Also the giant cacti, which we consider as trees of a special kind, not only because of their height and longevity, but also because of their multiple ecological roles in the desert canopy.

Large stand of Cardón, or Elephant cactus (Pachycereus pringlei) as a “Forest”, between Punta Prieta and Cataviña, Baja California.

Large stand of cardón, or elephant cactus (Pachycereus pringlei), mixed with Boojum as a “Forest”, between Punta Prieta and Cataviña, Baja California.

But, we wonder, where are the large hardwood trees that formerly contributed to the gallery or riparian forests canopies, judging from historic records? Where are the mesquites (Prosopis glandulosa) from which so many roof beams and kitchen tables were made, and the incredibly hard-wooded Ironwood?

Ironwood (Olneya tesota) in the Tucson Mountain Park, near Tucson, Arizona.

Ironwood (Olneya tesota) in the Tucson Mountain Park, near Tucson, Arizona.

Both species were heavily over-used in the past for firewood and charcoal production as well as construction wood, but Ironwood also appears to be surprisingly sensitive to drought and can die suddenly. In much of Baja California, except on the islands, what is left in the canopy is the softwoods, of little or no energetic value, such as the charming but soft-wooded, swollen-trunked elephant tree, often growing with columnar cacti, and the boojum.

The beautiful white-stemmed Elephant tree (Pachycormus discolor) growing with Cardón and Cirio, near Cataviña, Baja California.

The beautiful white-stemmed elephant tree (Pachycormus discolor) growing with cardón and cirio, near Cataviña, Baja California.

The take-home message is this: let us never forget the forest for the trees, in the compelling and urgent context of desert and dryland restoration.

Daniel Pauly’s Shifting Baseline Syndrome is more than ever relevant nowadays, not only to fisheries but also to the restoration of desert canopies. If we want to get serious about restoring desert and dryland ecosystems, we have to imagine what the canopies – however spatially constricted and reduced in diversity they are today – could have looked like 100 years ago, and think how they could look 100 – 300 years from now.

Guadalupe Island, Baja California: Invasive mammal eradication and perspectives for ecological restoration

James and Thibaud Aronson are working on a book, with James’s longtime collaborator Edouard Le Floc’h, on “desert canopies” and ecological restoration in arid and semi-arid regions of the world. They report here on the first leg of their trip to Baja California, Mexico.

Isla Guadalupe is a large volcanic island (250 km²), 240 km west of northern Mexico, with fewer than 150 permanent inhabitants. Approximately one-fifth of the island’s 150 native plant species are endemic. Of particular interest are the remnant populations of trees in the foggy, northern highlands of the island, including an endemic variety of Monterey pine (Pinus radiata var. binata), and the endemic cypress.

Guadalupe cypress (Hersperocyparis guadalupensis) in the “sky island” on the central highlands of the island.

Guadalupe cypress (Hesperocyparis guadalupensis) in the “sky island” on the central highlands of the island.

Three additional tree species survive in small populations : an endemic oak (Quercus tomentella), California juniper (Juniperus californica) and an endemic fan palm (Brahea edulis). At the southern end, there are remnants of both chapparal and matorral shrublands including taxa with Californian affinities and others from the Sonoran desert biome. The southern tip is very dry – with just 120 mm (5 in.) of mean annual rainfall. The northern half is mountainous with 250 mm (10 in.) of annual rain, and thick fogs that double or triple the effective precipitation.

People first came to the island in the early 19th century. By 1850, sailors had introduced goats to provide a meat reserve for passing ships. Not surprisingly, the goat population exploded, reaching an estimated 100,000 animals by 1870. Over-grazing led to the disappearance of entire plant communities and several dozen endemic species. One example is Hesperelaea palmeri, an endemic member of the olive family. Particularly appreciated by goats, it was gone by 1870. Domestic cats got to the island somewhat later, probably introduced intentionally to control the mice. The cats went feral, and had an enormous impact on the extremely tame birds, both endemic land birds, and breeding seabirds.

By the early 20th century, 6 of the 9 endemic land birds had gone extinct, as well as an endemic seabird. Meanwhile, the Guadalupe fur seal and the northern elephant seal were hunted relentlessly, the former for its fur, the latter for its blubber. The hunting only stopped in 1894, when both species were thought to be extinct. Happily, both species did in fact survive, albeit in extremely small numbers; the entire fur seal population dropped to 15 individuals. In 1928, the island became a set-aside reserve and seal populations finally started to recover, and today, they number 20,000!

Fur seal (Arctocephalus townsendi) on Isla Guadalupe, March, 2015.

Fur seal (Arctocephalus townsendi) on Isla Guadalupe, March, 2015.

The northern elephant seals have done even better. They have recolonized much of the northern Pacific, and the total population is more than 150,000 individuals.

Elephant seal (Mirounga angustirostris) on Isla Guadalupe, March, 2015.

Elephant seal (Mirounga angustirostris) on Isla Guadalupe, March, 2015.

On land, however, things kept worsening. The goat numbers stabilized around 15,000. As a result of over-grazing, most of the island was stripped to bare soil and rocks; only a few hundred trees survived and goats ate every seedling they produced. Cats caused enormous mortality in breeding seabirds and one of the remaining three endemic land birds, the Guadalupe Junco (Junco insularis), was headed towards extinction, with only 50-100 individuals left.

That’s when the Group for Ecology and Island Conservation (GECI) got in gear, and it’s thanks to them that things are looking up. Since 1995, this NGO has eradicated 48 populations of invasive mammals – mostly sheep, goats, cats, and mice – on 30 Mexican islands. They got to Guadalupe in 2002 and started an intensive eradication campaign. By 2007, the goats were gone. Within a year, the trees had produced thousands of recruits, which today are several meters high, in the case of both the pine and the cypress. In fact, in 2008, a fire burned through a large portion of the remaining stand of cypress. A few years earlier, this would have been a catastrophe. But without goats to eat them, thousands of seedlings sprouted immediately all over the burnt area and are growing nicely, thanks not only to the absence of goats, but also  to the heavy fogs, which provide favorable conditions for the seedlings. Besides, half a dozen native shrubs, including some endemic species, have reappeared in large numbers  in many parts of the island. Several species which were though extinct have been rediscovered, and one new species has been discovered as well.

All is not well, however, in the invasives department, nor in soil conservation. Dozens of species of herbs and grasses from the Mediterranean Basin and Europe are prevalent in open areas, and there are dramatic signs of soil erosion. Former shrublands – matorral and chaparral – are deeply degraded everywhere on the island. Half a dozen species of native shrubs are re-colonizing certain areas and acting as very effective pioneer species. These are being watched and probably can be used in active restoration efforts in the future.

Feral cats and several kinds of mice are still present and continue to prey on birds. However, a fence now protects the southern tip of the island, which is home to a breeding colony of the Laysan albatross, one of few albatross populations in the world which is growing in numbers.

Laysan albatross (Phoebastria immutabilis) breeding and raising chicks on Isla Guadalupe.

Laysan albatross (Phoebastria immutabilis) breeding and raising chicks on Isla Guadalupe.

Laysan albatross

To date, GECI has focused on eradicating invasive mammals, mainly to protect marine birds. The regeneration of the island’s vegetation was a happy by-product. However, they are now seeing the potential for taking a more active hand in restoring the islands’ plant communities. We suggested several approaches. One would be the establishment of plant nurseries to support both ex-situ conservation and reintroduction of plants within experimental plots set up to study what approaches are most effective for different plants, in different parts of the island. There are only 30 to 40 adult oak trees left on the island and less than 10 known Junipers. Unlike the endemic cypress, pine, and fan palm, neither the oak nor the juniper is recovering. Active intervention will be needed to reconstitute mixed conifer-oak woodlands and to bring the fan palm populations back to their former glory. Finally, some heavy work is needed in relation to water and soil management, and roughly 400 feral domestic cats still run free on the island. Total eradication will be extremely costly, but GECI hopes to achieve it by 2025. As is the case in Madagascar, and Sri Lanka, restorationists must learn how to cope with and manage fire.

With all this in mind, can our friends from GECI initiate a sustainable restoration process on the entire island, ideally within a coherent conservation, management, and restoration plan? Also, can the restoration work underway serve as a prototype for restoration on other islands, e.g., Mauritius and Madagascar where MBG scientists are already working?

Spontaneous Guadalupe cypress regeneration following the fire of 2008.

Spontaneous Guadalupe cypress regeneration following the fire of 2008.