Global change impacts on cacti (Cactaceae): current threats, challenges and conservation solutions (original) (raw)
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Seedling survival of three endemic and threatened Mexican cacti under induced climate change
Plant Species Biology, 2016
Human-induced warming may increase the risk of local extinction for plant species with low tolerance of elevated temperatures. The Chihuahuan desert harbors the highest diversity of globose cacti in the world and most of them are at risk of extinction. Predictive models of climate change indicate an increase in summer temperature of 1-2°C by 2030 for this desert. Nevertheless, studies on the vulnerability of cacti species in early development phases to future climate change are scarce. We assessed the survival of three threatened cacti species from the Chihuahuan desert under induced warming. Open-top chambers (OTCs) were used to simulate the effect of global warming on 2-year seedlings of Echinocactus platyacanthus f. visnaga, Ferocactus histrix and Stenocactus coptonogonus. OTCs had higher temperature and lower humidity than control plots, and these elevated temperatures reduced seedling survival. Within the OTCs, no living individuals of any species were found after 105 days. Conversely, in the control plots, the three cacti species showed variable numbers of survivors after this period. Therefore the predicted global warming scenarios will greatly limit plant recruitment and the long-term persistence of natural populations of Mexican endemic cacti species.
Winners and losers in the predicted impact of climate change on cacti species in Baja California
Plant Ecology, 2020
The Cactaceae is considered one of the most threatened taxa in the world. However, the extent to which climate change could compromise the conservation status of this group has rarely been investigated. The present study advances this issue under three specific aims: (1) to assess the impact of climate change on the distribution of endemic cacti species in the Baja California Peninsula (n = 40), (2) to study how the impact of climate change is distributed in this group according to the species' conservation status, and (3) to analyze how these impacts are organized from a biogeographical and functional perspective. We addressed these objectives under three socioeconomic emission pathways (RCP 2.6, 4.5, and 8.5), and using two extreme migration scenarios: full climate change tracking and no migration. Altogether, all socioeconomic emission pathways under the two extreme migration scenarios show consistency regarding the identity of the species most vulnerable to climate change, and depict a discrepant future scenario that has, on one hand, species with large potential habitat gains/stability (winners); and on the other, species with large habitat reductions (losers). Our work indicates that winner species have a tropical affinity, globose growth, and includes most of the currently threatened species, whereas loser ones are in arid and Mediterranean systems and are mostly non-threatened. Thus, current and future threat factors do not overlap in the biogeographic and taxonomic space. That reveals a worrisome horizon at supraspecific levels in the study area, since the total number of threatened species in the future might largely increase. Keywords Species traits Á Endangered cacti Á Growth form Á Sonoran Desert Á Mexico Communicated by Hsiao-Hsuan Wang.
High proportion of cactus species threatened with extinction
A high proportion of plant species is predicted to be threatened with extinction in the near future. However, the threat status of only a small number has been evaluated compared with key animal groups, rendering the magnitude and nature of the risks plants face unclear. Here we report the results of a global species assessment for the largest plant taxon evaluated to date under the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, the iconic Cactaceae (cacti). We show that cacti are among the most threatened taxonomic groups assessed to date, with 31% of the 1,478 evaluated species threatened, demonstrating the high anthropogenic pressures on biodiversity in arid lands. The distribution of threatened species and the predominant threatening processes and drivers are different to those described for other taxa. The most significant threat processes comprise land conversion to agriculture and aquaculture, collection as biological resources, and residential and commercial development. The dominant drivers of extinction risk are the unscrupulous collection of live plants and seeds for horticultural trade and private ornamental collections, smallholder livestock ranching and smallholder annual agriculture. Our findings demonstrate that global species assessments are readily achievable for major groups of plants with relatively moderate resources, and highlight different conservation priorities and actions to those derived from species assessments of key animal groups.
Functional trade-offs in succulent stems predict responses to climate change in columnar cacti
Journal of Experimental Botany, 2014
Columnar cacti occur naturally in many habitats and environments in the Americas but are conspicuously dominant in very dry desert regions. These majestic plants are widely regarded for their cultural, economic, and ecological value and, in many ecosystems, support highly diverse communities of pollinators, seed dispersers, and frugivores. Massive amounts of water and other resources stored in the succulent photosynthetic stems of these species confer a remarkable ability to grow and reproduce during intensely hot and dry periods. Yet many columnar cacti are potentially under severe threat from environmental global changes, including climate change and loss of habitat. Stems in columnar cacti and other cylindrical-stemmed cacti are morphologically diverse; stem volume-to-surface area ratio (V:S) across these taxa varies by almost two orders of magnitude. Intrinsic functional trade-offs are examined here across a broad range of V:S in species of columnar cacti. It is proposed that variation in photosynthetic gas exchange, growth, and response to stress is highly constrained by stem V:S, establishing a mechanistic framework for understanding the sensitivity of columnar cacti to climate change and drought. Specifically, species that develop stems with low V:S, and thus have little storage capacity, are expected to express high mass specific photosynthesis and growth rates under favourable conditions compared with species with high V:S. But the trade-off of having little storage capacity is that low V:S species are likely to be less tolerant of intense or long-duration drought compared with high V:S species. The application of stable isotope measurements of cactus spines as recorders of growth, water relations, and metabolic responses to the environment across species of columnar cacti that vary in V:S is also reviewed. Taken together, our approach provides a coherent theory and required set of observations needed for predicting the responses of columnar cacti to climate change.
New Phytologist, 2014
"Summary Succulent plants are widely distributed, reaching their highest diversity in arid and semi-arid regions. Their origin and diversification is thought to be associated with a global expansion of aridity. We test this hypothesis by investigating the tempo and pattern of Cactaceae diversification. Our results contribute to the understanding of the evolution of New World Succulent Biomes. We use the most taxonomically complete dataset currently available for Cactaceae. We estimate divergence times and utilize Bayesian and maximum likelihood methods that account for nonrandom taxonomic sampling, possible extinction scenarios and phylogenetic uncertainty to analyze diversification rates, and evolution of growth form and pollination syndrome. Cactaceae originated shortly after the Eocene–Oligocene global drop in CO2, and radiation of its richest genera coincided with the expansion of aridity in North America during the late Miocene. A significant correlation between growth form and pollination syndrome was found, as well as a clear state dependence between diversification rate, and pollination and growthform evolution. This study suggests a complex picture underlying the diversification of Cactaceae. It not only responded to the availability of new niches resulting from aridification, but also to the correlated evolution of novel growth forms and reproductive strategies."
The Role of Botanical Gardens in the Conservation of Cactaceae
BioScience, 2016
The family Cactaceae contains some of the most iconic species of succulent plants, many of which are valued for their cultural, economic, and ecological value. However, over 75% of all species of cacti are in decline, largely because of the effects global environmental changes (GEC), including climate change. Mitigating the impacts of GEC on cacti will require a coordinated effort that combines conservation, research, and education. Botanical gardens are uniquely positioned to lead such an effort because their living collections and programs focus on conservation and research. A coordinated network of botanical gardens-with living collections serving as experimental gardens-could become a crucial hub for studying the impacts of climate change on cacti. A network of botanical gardens could open previously untapped funding avenues to support the research, education, and conservation of cacti and provide resources for underfunded botanical gardens in Latin America.
Climate Change Vulnerability Assessment of Imperiled Plants in the Mojave Desert
Endangered Plants, 2021
The Mojave Desert in the southwestern United States is one of the hottest and driest areas of North America. Climate change is likely to exacerbate these conditions. The region is home to many endemic plant species, including 24 federally threatened species. The impact of climate change factors on these sensitive Mojave Desert species is relatively unknown. Here we used a climate change vulnerability assessment to determine which imperiled plants may be most affected by changing climatic conditions. We evaluated the vulnerability of each species under future climate scenarios and calculated scores using metrics such as exposure, sensitivity, niche breadth, and dispersal capability. We found that most listed plant species were vulnerable to climate change, with 21% (N = 5) classified as extremely vulnerable, 25% (N = 6) classified as highly vulnerable, and 42% (N = 10) classified as moderately vulnerable. Contributing factors most frequently associated with vulnerability included var...
Diversity and conservation in the cactus family
Desert Plants, 2010
Cacti are conspicuous elements of the Western hemisphere. They have long attracted attention due to their peculiar biology, and have maintained close relationships with local settlers. Cacti are used as food, fodder, medicinal and ornamental plants, and as a source of wood. The greatest diversity of this family is recorded in Mexico, with 586 species, followed by Brazil, Argentina, Bolivia and Peru. These countries are also the richest in endemic species. The underlying factors affecting diversity patterns are varied and include temperature, rainfall and geological history. Cacti are threatened by loss and degradation of habitat, and illegal collection. Though it is commonly stated that many species are endangered, most have not yet been evaluated. Due to the growing impact of human activities on biodiversity it is necessary to increase conservation actions to preserve this interesting group of plants, especially in South American countries where knowledge and conservation of cacti are still incipient.