Out of the frying pan and into the fire: effects of volcanic heat and other stressors on the conservation of a critically endangered plant in Hawai‘i

Abstract

Summary 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.

Detection of Geothermal Anomalies in Hydrothermal Systems Using ASTER Data: The Caldeiras da Ribeira Grande Case Study (Azores, Portugal)

“…According to the Köppen Climate Classification, the temperate and rainy climate of the Azores enhances vegetative vigor. This factor also highlights the relevance of the current study since, despite some effect of seasonality on the vigor of natural vegetation, the maintenance of low NDVI values can constitute important signs of permanent change on the surface related to the deep-derived contribution, as evidenced in volcanoes such as Yellowstone [ 22 ] and Hawai’i [ 57 ], where alterations in vegetation vigor due to thermal anomalies were detected. Identifying and understanding the land use dynamics in the study area are essential to minimize evaluation errors as mentioned above.…”

Environmental Impact of Bush Burning on the Physico-Chemistry of Mangrove Soil at Eagle Island, Niger Delta, Nigeria

“…The growth of weeds on the degraded section of the forest attracts non-mangrove species such as arthropods (butterflies, bees, wasp and ants), rodents (bush rats), snakes and different bird species. The bushes around the forest are deliberately set on fire which endangers the entire ecosystem, this leads to an adverse effect of heat on the soil and vegetation [6] [7]. Burning activities occur during the dry season when the leaves of the plants are dry (October-March) and easily combustible.…”