Phenology studies the time at which events in the life cycle of a species occur sand how they are related to environmental cues. Patterns of change in phenology at different scales can be used as an indicator of ecosystem changes and climate change, but the data necessary to detect these changes can be difficult to obtain due to their temporal and regional dimensions. Citizen science can contribute to generate large amounts of data on phenological changes at wide geographical scales that would be almost impossible for professional scientists to generate, but the quality and reliability of these data are often questioned. The objective of this study was to evaluate the use of a biodiversity observation citizen science platform based on photographic information as a potential source of large-scale phenological information, and to identify the key benefits and limitations of this type of information source. We used the Naturalista photographic databases for two invasive species in a tropical region:Leonotis nepetifoliaandNicotiana glauca. The photographs were classified into different phenophases (initial growth, immature flower, mature flower, dry fruit) by three groups of volunteers: a group of experts, a trained group with information on the biology and phenology of both species, and an untrained group. The degree of reliability of the phenological classifications was estimated for each group of volunteers and each phenophase. The degree of reliability of the phenological classification of the untrained group was generally very low for all phenophases. The group of trained volunteers showed accuracy levels for the reproductive phenophases that equaled the degree of reliability among the expert group, regardless of species, and was consistent across phenophases. We conclude that volunteer classification of photographic information contained in biodiversity observation platforms can provide phenological information with high geographic coverage and an increasing temporal coverage on general phenological patterns of species with wide distributions but has limited applicability in the identification of exact start and end dates. and peaks of the different phenophases.

Lophophora diffusa (Cactaceae) –an endangered species– known as peyote or peyote queretano– is of great ecological relevance because of its medicinal and ornamental use by native peoples and collectors. Little is known about the population of this species and no strategies exist for their use since its cultivation and usage is prohibited in Mexico. Thus, the objective of the present research is to describe population dynamics in a locality of the state of Querétaro, México. For this purpose, 380 individuals were followed through four annual and one quinquennial censuses. From these data, the population structure was determined, including the finite population growth rate (λ), stable size structure, reproductive value, relative importance of size categories and demographic processes (permanence, growth, and fecundity) for each period by using transition matrixes. Moreover, future population estimations were performed, showing scarcity of seedlings and adult plants of greater size, where λ indicates a population decline that oscillates between 2 and 20%. The most important demographic process was survival, where the adult 2 category resulted essential. The projections indicate that the population may disappear in a period of less than 50 years. Therefore, the proposal is to revise the Mexican legislation to allow a regulated cultivation with the purpose of protecting the wild populations of the species and its habitat.

Succulent plants in arid ecosystems exhibit contrasting strategies to cope with high irradiance, thermal stress, and water limitation. We evaluated spatial distribution, microhabitat use, nurse identity, and orientation beneath canopies for two threatened globose cacti from the Querétaro semi-desert (Mexico): Ariocarpus kotschoubeyanus and Lophophora diffusa. One site with high population density was selected for each species, where 10 plots were established (9 m² for A. kotschoubeyanus and 49 m² for L. diffusa). The study aims to evaluate whether species-specific recruitment patterns are associated with differential dependence on nurse-plant microhabitats under conditions of radiation and thermal stress. We hypothesized that: (1) both species exhibit aggregated spatial distributions but differ in their reliance on nurse-mediated microclimatic buffering; and (2) nurse-plant identity and orientation patterns vary between species, reflecting species-specific ecophysiological thresholds to irradiance and heat stress. Both species showed strongly aggregated spatial distributions (Hopkins index > 0.8), indicating recruitment constrained by microsite heterogeneity. However, their stress-adaptation strategies differed markedly. A. kotschoubeyanus occurred predominantly in open microsites (79%), consistent with its geophytic growth form and tolerance to high radiation and temperature extremes. In contrast, L. diffusa was strongly associated with nurse plants (78%), particularly Larrea tridentata and Bursera fagaroides, and preferentially established on eastern canopy exposures that reduce afternoon heat load. These patterns reflect species-specific ecophysiological thresholds linked to radiation tolerance and microclimatic buffering. Facilitation in globose cacti is therefore trait-mediated and context-dependent. Maintaining perennial shrub diversity is essential to preserve the microhabitats that sustain recruitment and persistence of stress-sensitive succulents under increasing climatic aridity.