Loss of local biodiversity resulting from abrupt environmental change is a significant environmental problem throughout the world. Extinctions of plants are particularly important yet are often overlooked. Drawing from a case in Hawai‘i, a global hotspot for plant and other extinctions, we demonstrate an effort to better understand and determine priorities for the management of an endangered plant (‘Ihi makole or Portulaca sclerocarpa) in the face of rapid and extreme environmental change. Volcanic heat emissions and biological invasions have anecdotally been suggested as possible threats to the species. We integrated P. sclerocarpa outplanting with efforts to collect geological and ecological data to gauge the role of elevated soil temperatures and invasive grasses in driving P. sclerocarpa mortality and population decline. We measured soil temperature, soil depth, surrounding cover and P. sclerocarpa survivorship over three decades. The abundance of wild P. sclerocarpa decreased by 99.7% from the 1990s to 2021. Only 51% of outplantings persisted through 3–4 years. Binomial regression and structural equation modelling revealed that, among the variables we analysed, high soil temperatures were most strongly associated with population decline. Finding the niche where soil temperatures are low enough to allow P. sclerocarpa survival but high enough to limit other agents of P. sclerocarpa mortality may be necessary to increase population growth of this species.

As natural and anthropogenic forcings impel anticipated climate change, their effects on biodiversity and environmental sustainability are evident. A fundamental question that is often overlooked is: which changes in climate will cause the redistribution or extinction of threatened species? Here, we mapped and modelled the current and future geographical distributions of the four threatened medicinal plants – Aconitum heterophyllum Wall. ex Royle, Fritillaria cirrhosa D.Don, Meconopsis aculeata Royle and Rheum webbianum Royle – in Kashmir Himalaya using maximum entropy (MaxEnt) modelling. Species occurrence records were collated from detailed field studies carried out between the years 2010 and 2020. Four general circulation models for Representative Concentration Pathway (RCP) 4.5 and RCP8.5 climate change scenarios were chosen for future range changes over periods around 2050 (average for 2041–2060) and 2070 (average of 2061–2080). Notable differences existed between species in their responses to predictive environmental variables of temperature and precipitation. Increase in the most suitable habitat, except for A. heterophyllum and R. webbianum, were evident across Himalayan Mountain regions, while the Pir Panjal mountain region exhibited a decrease for all four species under future climate change scenarios. This study exemplifies the idiosyncratic response of narrow-range plants to expected future climate change and highlights conservation implications.

Seed predation has been suggested to play a crucial role in plant population dynamics and could act as a strong selective force in the evolution of plant traits such as plant phenology, size and number of flowers. The loss of seeds could be particularly threatening for population maintenance of rare plant species. We investigated the influence of seed predators on plant fitness of the rare monocarpic thistle Cirsium decussatum. We tested the following hypotheses: (1) pre-dispersal seed predators reduce the number of dispersed propagules; (2) seed predators select larger inflorescences as oviposition sites; (3) the size of the capitulum is correlated with seed productivity; and (4) seed predators compete for the oviposition sites. We identified ten insect taxa from different taxonomic groups in the capitula of C. decussatum. Terellia longicauda larvae (Diptera: Tephritidae) were the most common. The presence of the flies’ larvae was positively correlated with the predation level in the capitula. Females of T. longicauda selected larger inflorescences for laying eggs that may increase offspring fitness as larger inflorescences promise more food resources. We could not prove the presence of competition between insect species inhabiting the capitula. Our data suggest, however, that T. longicauda, a specialized seminophagous dipteran, is one of the factors that negatively influence the fitness of threatened C. decussatum, lowering significantly the seed pool. Terellia longicauda potentially acts as a strong selective force in the evolution of C. decussatum inflorescence size.