Warm winters challenge the cultivation of temperate species in South America—a spatial analysis of chill accumulation

Winter chill accumulation plays a crucial role in determining the moment of bud burst in temperate fruit and nut trees, and insufficient chill can greatly limit yield potentials. To assess future cultivation options for such species in South America, we estimated winter chill through a spatial analysis. We used historical data (1980–2017) from 158 weather stations to calibrate a weather generator and produce temperature data for 10 historical and 60 future scenarios. We computed Safe Winter Chill (SWC, corresponding to the 10th quantile of a chill distribution) for the period 1980–2017 and for all historical and future weather scenarios and developed a framework to interpolate SWC for the continent using the Kriging method. To improve the interpolation, we applied a 3D correction model based on two co-variables (means of daily temperature extremes in July). Our results suggest important chill declines in southern Brazil and central Chile. By 2050 under the global warming scenario RCP4.5 (Representative Concentration Pathway), absolute SWC in these regions may reach a median of 18.7 and 39.6 Chill Portions (CP), respectively. Projections are most alarming for a strong global warming scenario (RCP8.5). In southern South America, adequate SWC levels of about 60 CP may be expected even under the RCP8.5 scenario. Our results highlight the need for climate change adaptation measures to secure temperate fruit production in important growing regions of South America. The procedure we developed may help farmers and practitioners across South America estimate future SWC to adapt their orchards to future challenges.

Changes in the microbial community structure triggered by permafrost peat thawing

An increase in permafrost temperature, accompanied by the melting and release of buried organic carbon, is one of the elements of the global warming scenario. To understand the way ecosystems respond to environmental changes, it is necessary to elucidate the factors affecting the distribution and activity of microbes in permafrost soils, which have been poorly studied so far. Meanwhile, they can have significant implications for nutrient cycling and related processes. Our research is devoted to assessing changes in the structure of the microbial community due to the melting of the palsa permafrost layer caused by the fire in 2007. The ecological-trophic groups of microorganisms of the territories changed under the influence of a natural fire in comparison with undisturbed analogs have been studied. It was revealed that the number of microorganisms in most groups on the palsa, affected by fire, is statistically significantly higher than the number of microorganisms in the undisturbed area.

Modelling the incubation microclimate to predict offspring sex ratios and hatching phenology in tuatara (Sphenodon punctatus)

<p>Successful conservation of terrestrial biodiversity requires understanding and predicting the impacts of rapid climate warming on the suitability of both current and potential future habitats. Most predictions of range shifts and other population-scale effects of climate change rely to some extent on statistical links between a species' known geographical distribution and the suite of environmental conditions experienced within that space. However, species' responses to climate change are likely to be more complex than can be represented by the projection of current species-environment relationships into unknown environments. An important goal in biodiversity conservation is the development of quantitative tools with which to assess habitat suitability independently of distributions. In populations of oviparous species, climate change and habitat modification may have distinct effects on different life stages. Temperatures that are well within the thermal tolerance range of adults, for example, may affect embryonic development rates, hatching phenology, or offspring survival and phenotype. I examined how environmental variation may affect the thermal suitability of habitat for facilitating embryonic development and maintaining balanced sex ratios in tuatara (Sphenodon punctatus), an endemic New Zealand reptile with temperature-dependent sex determination (TSD). Once widespread throughout New Zealand, populations are now restricted to offshore islands and fenced mainland sanctuaries, though establishment of additional populations via translocation is ongoing. Due to intensive conservation efforts, tuatara are not classified as an endangered species, but, like other species in which hatchling sex is determined by the incubation environment, populations are potentially at risk from the detrimental effects of sex-ratio bias. I conducted two seasons of field work on the island of Takapourewa to quantify the relationship between rapid vegetation succession and selection of nesting areas. I then used a variety of predictive models to link data on nesting behaviour collected in the field with the microclimate conditions experienced by nesting female tuatara and developing embryos. Using mechanistically modelled soil temperature data, I generated predictions of incubation temperatures, offspring sex ratios, and hatching dates for two populations of tuatara on environmentally distinct islands, Takapourewa and Hauturu, under current and projected future climate scenarios. Finally, I classified the thermal suitability of sites on Hauturu for facilitating successful embryonic development and created geospatial surfaces defining suitable nesting locations adjacent to tuatara habitats. Offspring sex ratios on both islands are unlikely to become male-biased if the magnitude of climate warming observed over the next century more closely matches the minimum, rather than the maximum, projected warming scenario. On Takapourewa, the timing of nesting will be critical in determining whether sex ratios become male-biased under a scenario of maximum climate warming. Earlier nesting may also lead to shifts in hatching phenology under either scenario of climate warming. Warmer annual temperatures on Hauturu are more likely to lead to heavily male-biased offspring sex ratios under the maximum warming scenario. Female tuatara on Hauturu do not need to travel away from their current habitats to locate suitable nesting sites. Monitoring the population to quantify nesting behaviour on the island will be important for determining whether females' choices of incubation microclimates can compensate for the sex ratio-biasing effects of climate change.</p>

Modelling the incubation microclimate to predict offspring sex ratios and hatching phenology in tuatara (Sphenodon punctatus)

<p>Successful conservation of terrestrial biodiversity requires understanding and predicting the impacts of rapid climate warming on the suitability of both current and potential future habitats. Most predictions of range shifts and other population-scale effects of climate change rely to some extent on statistical links between a species' known geographical distribution and the suite of environmental conditions experienced within that space. However, species' responses to climate change are likely to be more complex than can be represented by the projection of current species-environment relationships into unknown environments. An important goal in biodiversity conservation is the development of quantitative tools with which to assess habitat suitability independently of distributions. In populations of oviparous species, climate change and habitat modification may have distinct effects on different life stages. Temperatures that are well within the thermal tolerance range of adults, for example, may affect embryonic development rates, hatching phenology, or offspring survival and phenotype. I examined how environmental variation may affect the thermal suitability of habitat for facilitating embryonic development and maintaining balanced sex ratios in tuatara (Sphenodon punctatus), an endemic New Zealand reptile with temperature-dependent sex determination (TSD). Once widespread throughout New Zealand, populations are now restricted to offshore islands and fenced mainland sanctuaries, though establishment of additional populations via translocation is ongoing. Due to intensive conservation efforts, tuatara are not classified as an endangered species, but, like other species in which hatchling sex is determined by the incubation environment, populations are potentially at risk from the detrimental effects of sex-ratio bias. I conducted two seasons of field work on the island of Takapourewa to quantify the relationship between rapid vegetation succession and selection of nesting areas. I then used a variety of predictive models to link data on nesting behaviour collected in the field with the microclimate conditions experienced by nesting female tuatara and developing embryos. Using mechanistically modelled soil temperature data, I generated predictions of incubation temperatures, offspring sex ratios, and hatching dates for two populations of tuatara on environmentally distinct islands, Takapourewa and Hauturu, under current and projected future climate scenarios. Finally, I classified the thermal suitability of sites on Hauturu for facilitating successful embryonic development and created geospatial surfaces defining suitable nesting locations adjacent to tuatara habitats. Offspring sex ratios on both islands are unlikely to become male-biased if the magnitude of climate warming observed over the next century more closely matches the minimum, rather than the maximum, projected warming scenario. On Takapourewa, the timing of nesting will be critical in determining whether sex ratios become male-biased under a scenario of maximum climate warming. Earlier nesting may also lead to shifts in hatching phenology under either scenario of climate warming. Warmer annual temperatures on Hauturu are more likely to lead to heavily male-biased offspring sex ratios under the maximum warming scenario. Female tuatara on Hauturu do not need to travel away from their current habitats to locate suitable nesting sites. Monitoring the population to quantify nesting behaviour on the island will be important for determining whether females' choices of incubation microclimates can compensate for the sex ratio-biasing effects of climate change.</p>

Increasing spring dust storms in the future over the Taklimakan Desert, Northwest China: implications from changes in circulation pattern frequency in CMIP6

Dust storms over the Taklimakan Desert (TD), Northwest China, not only influence human health but also affect regional climate through direct effects of dust aerosols on solar and longwave radiation. The Coupled Model Intercomparisons Project Phase 5 (CMIP5) models project a decrease in dust storms because of a decrease in dust emissions over the TD in the future under warming scenarios. However, inaccurate simulations of dust emissions cause the CMIP5 models to simulate dust storms poorly. Here we analyzed typical circulation patterns that initiate dust storms over the TD and examined changes in the frequency of typical circulation patterns derived from the CMIP6 models in an extreme warming scenario. The results show that there will be an increase in typical circulation pattern frequency in the latter half of the 21st century compared with 1958-2014, implying an increase in dust storms over the TD in the future under the extreme warming scenario. The increase in dust storms over the TD may be related to an increase in synoptic activities in the future from the Middle Asia to the TD, which is caused by a southern movement of subtropical westerly jet stream under the extreme warming scenario.

Protected-area targets could be undermined by climate change-driven shifts in ecoregions and biomes

Expanding the global protected area network is critical for addressing biodiversity declines and the climate crisis. However, how climate change will affect ecosystem representation within the protected area network remains unclear. Here we use spatial climate analogs to examine potential climate-driven shifts in terrestrial ecoregions and biomes under a +2 °C warming scenario and associated implications for achieving 30% area-based protection targets. We find that roughly half of land area will experience climate conditions that correspond with different ecoregions and nearly a quarter will experience climates from a different biome. Of the area projected to remain climatically stable, 46% is currently intact (low human modification). The area required to achieve protection targets in 87% of ecoregions exceeds the area that is intact, not protected, and projected to remain climatically stable within those ecoregions. Therefore, we propose that prioritization schemes will need to explicitly consider climate-driven changes in patterns of biodiversity.