Open top chamber microclimate may limit photosynthetic processes in Antarctic lichen: Case study from King George Island, Antarctica

Long-term manipulated warming experiments using the open top chamber (OTC) approach tend to mimick the future climate and predict the changes in photosynthesis and production of vegetation under globally changed climate. In Antarctica, several long-term experiments are carried out recently. Here we report to the lichens grown in OTCs installed at the Fildes Peninsula (King George Island). The field study compares primary photochemical processes of photosynthesis in Antarctic lichen Placopsis antarctica grown for one year in OTC and compared to outside plot (control). We measured effective quantum yield of photosystem II (ΦPSII) of green algae part of thallus in 10 min. interval for 12 days. We examined the responses of diurnal ΦPSII to PAR in relation to environmental factors through continuous 12-d-long monitoring of chlorophyll fluorescence parameters ΦPSII in particular. Daily courses of ΦPSII and photosynthetic electron transport rate (ETR) to photosynthetically active radiation (PAR) and hydration state of thallus have been assumed to reflect changes in physiological status of P. antarctica in changing Antarctic environment. The data indicate that OTC microenvironment may lead to partial limitation of photosynthetic processes in P. antarctica during austral summer season. The limitation is caused by accelerated dehydration of thallus in OTC compared to the outside generally colder control plot, and thus shortened physiologically active period of lichens in OTC

Editorial: Revisiting the limits of plant life - plant adaptations to extreme terrestrial environments relating to astrobiology and space biology

Plants were essential to the early evolution of terrestrial life and colonization of the young Earth (Kapoor et al., 2023). Plant communities continue to colonize and transform our planet including the newest ecosystems formed post-glaciation, restoring those degraded by human activities and adapting to changing ecological conditions (Huston and Smith, 1987; Chapin et al., 1994; Yuan et al., 2020; Heim et al., 2021). Plants cannot move away from a harmful stimulus, and thus, have evolved remarkable strategies to survive and eventually thrive in harsh environments. Today, humanity is on the verge of exploring our solar system and beyond, eager to discover, answer fundamental questions, and search for extraterrestrial forms of life. Undoubtedly, plants are key organisms to successful deep space missions and independence from the provision of terrestrial resources, whether for long duration interplanetary travel or establishing permanent settlements. With this thought in mind, we have collated articles focusing on terrestrial plants from extreme environments and their adaptations to harsh conditions. This collective knowledge will advance the selection of desired plant characteristics relevant to human space mission

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-km² pixels (summarized from 8500 unique temperature sensors) across all the world’s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

The pioneer lichen Placopsis in maritime Antarctica: Genetic diversity of their mycobionts and green algal symbionts, and their correlation with deglaciation time

Since ice-free areas in Antarctica are predicted to increase by up to 25% before the end of this century, lichens such as the genus Placopsis will be important colonizers of these newly available grounds and will still be present in later successional stages of the lichen community. The main symbionts of Placopsis species are examined for 56 specimens collected from the South Shetland Islands, Antarctica using molecular (fungal and algal nrITS, fungal RPB1, algal rbcL sequences) and morphological methods. The specimens were collected from soils with different deglaciation times. Eight uni-algal photobiont cultures were obtained and analysed from two specimens. Placopsis antarctica and P. contortuplicata proved to be monophyletic and are sister species, only the former producing vegetative diaspores (soredia). Both share the same photobiont pool and are lichenized with two closely related species, Stichococcus antarcticus and S. allas. Two haplotypes of S. antarcticus are restricted to areas deglaciated for more than 5000 years and the volcanic Deception Island indicating a shift in the photobionts of Placopsis in the course of the soil and lichen community development. These photobiont haplotypes exhibit different ecological preferences, possibly leading to adaptation of the symbiotic entity to changing environmental conditions

Preliminary study of lichens of the order Peltigerales in the Ecological and Cultural Park Rucamanque in the Araucania Region, Chile

The Rucamanque Park houses some of the remnants of the Roble-Raul(-Coigue mixed forest in Central-South Chile. Cortical lichens were monitored in Renoval and in the Original Remnant Forest of Nothofagus obliqua (Mirb.) Oerst. We found differences in specific richness by tree species and between the Renoval (13 species) and the Original Remnant (7 species). The variables that affect the greatest richness are discussed, suggesting that the structure of the forest may play a key factor

Geoecology and Historical Heritage in the Ice-Free Area of Elephant Point (Antarctica). Proposal for Future Environmental Protection

The Antarctic Treaty provides the general environmental policies for all areas south of parallel 60 degrees S. In addition, some enclaves have a higher degree of environmental protection regulated by three categories: Antarctic Specially Protected Areas (ASPA), Antarctic Specially Managed Areas and Historic Sites or Monuments. Most of the protected areas in Antarctica have been designated based on the national geopolitical strategies, giving special attention to those areas where access and logistics are easier. This paper focuses on Elephant Point (Livingston, South Shetland Islands), an ice-free area of 1.16 km2 where activities are only regulated by the Antarctic Treaty System and no further environmental protection exists. By using a geoecological approach based on the geomorphology together with the distribution of the fauna and flora existing in the area, we have distinguished six geoecological environments in Elephant Point: Rotch glacier, proglacial environment, moraine system, bedrock plateaus, marine terraces and present-day beach. The distribution of fauna and flora is highly conditioned by the age of deglaciation as well as by the glacial, paraglacial and periglacial geomorphological landforms and processes. Besides this, five well preserved archaeological sites have been found in Elephant Point. These sites were used for sealers and whalers who sailed across the Maritime Antarctic during the eighteenth and nineteenth centuries. The rich biodiversity together with the high geomorphological and historical significance of this peninsula within the Maritime Antarctic constitutes the scientific basis to propose Elephant Point to be designated an ASPA in order to preserve the unique scientific heritage existing in this small peninsula

Sequestrate syndrome in Bondarzewia guaitecasensis (Fungi, Basidiomycota)? The case of Hybogaster giganteus revisited

Based on comparison of molecular, morphological and ecological data, we propose that Hybogaster giganteus Singer, a parasitic basidiomycete on stem bases and coarse roots of Nothofagus in Chile, is conspecifically related to the sympatric Bondarzewia guaitecasensis. According to our concept, H. giganteus is representing a sequestrate form of the latter and is hence recombined and formally described as Bondarzewia guaitecasensis f. gigantea; we further discuss the evidence that its sequestrate morphology may provide higher resistance to drought stress in early autumn, extending the sporulation season of the species

Inhibition of Primary Photosynthesis in Desiccating Antarctic Lichens Differing in Their Photobionts, Thallus Morphology, and Spectral Properties

Five macrolichens of different thallus morphology from Antarctica (King George Island) were used for this ecophysiological study. The effect of thallus desiccation on primary photosynthetic processes was examined. We investigated the lichens' responses to the relative water content (RWC) in their thalli during the transition from a wet (RWC of 100%) to a dry state (RWC of 0%). The slow Kautsky kinetics of chlorophyll fluorescence (ChlF) that was recorded during controlled dehydration (RWC decreased from 100 to 0%) and supplemented with a quenching analysis revealed a polyphasic species-specific response of variable fluorescence. The changes in ChlF at a steady state (Fs), potential and effective quantum yields of photosystem II (F-V/F-M, phi(PSII)), and nonphotochemical quenching (NPQ) reflected a desiccation-induced inhibition of the photosynthetic processes. The dehydration-dependent fall in F-V/F-M and phi(PSII) was species-specific, starting at an RWC range of 22-32%. The critical RWC for phi(PSII) was below 5%. The changes indicated the involvement of protective mechanisms in the chloroplastic apparatus of lichen photobionts at RWCs of below 20%. In both the wet and dry states, the spectral reflectance curves (SRC) (wavelength 400-800 nm) and indices (NDVI, PRI) of the studied lichen species were measured. Black Himantormia lugubris showed no difference in the SRCs between wet and dry state. Other lichens showed a higher reflectance in the dry state compared to the wet state. The lichen morphology and anatomy data, together with the ChlF and spectral reflectance data, are discussed in relation to its potential for ecophysiological studies in Antarctic lichens