Arctic warming on two continents has consistent negative effects on lichen diversity and mixed effects on bryophyte diversity

Little is known about the impact of changing temperature regimes on composition and diversity of cryptogam communities in the Arctic and Subarctic, despite the well‐known importance of lichens and bryophytes to the functioning and climate feedbacks of northern ecosystems. We investigated changes in diversity and abundance of lichens and bryophytes within long‐term (9–16 years) warming experiments and along natural climatic gradients, ranging from Swedish subarctic birch forest and subarctic/subalpine tundra to Alaskan arctic tussock tundra. In both Sweden and Alaska, lichen diversity responded negatively to experimental warming (with the exception of a birch forest) and to higher temperatures along climatic gradients. Bryophytes were less sensitive to experimental warming than lichens, but depending on the length of the gradient, bryophyte diversity decreased both with increasing temperatures and at extremely low temperatures. Among bryophytes, Sphagnum mosses were particularly resistant to experimental warming in terms of both abundance and diversity. Temperature, on both continents, was the main driver of species composition within experiments and along gradients, with the exception of the Swedish subarctic birch forest where amount of litter constituted the best explanatory variable. In a warming experiment in moist acidic tussock tundra in Alaska, temperature together with soil ammonium availability were the most important factors influencing species composition. Overall, dwarf shrub abundance (deciduous and evergreen) was positively related to warming but so were the bryophytes Sphagnum girgensohnii, Hylocomium splendens and Pleurozium schreberi; the majority of other cryptogams showed a negative relationship to warming. This unique combination of intercontinental comparison, natural gradient studies and experimental studies shows that cryptogam diversity and abundance, especially within lichens, is likely to decrease under arctic climate warming. Given the many ecosystem processes affected by cryptogams in high latitudes (e.g. carbon sequestration, N₂‐fixation, trophic interactions), these changes will have important feedback consequences for ecosystem functions and climate.     

生物土壤结皮对全球气候变化的响应

生物土壤结皮在干旱、半干旱区和极地、亚极地区等脆弱生态区广泛存在,生物土壤结皮对脆弱生态系统的稳定、碳氮循环和生态平衡等具有重要的生态意义.概述了脆弱生态区生物结皮的碳氮循环与气候变化关系,综合分析了脆弱生态区生物结皮对气候变暖、降水变化和UV-B增加的响应.分析认为应该加强区域尺度下干旱与半旱区生物结皮对气候变化响应研究.     

Mycorrhizas and global environmental change: research at different scales

Global environmental change (GEC), in particular rising atmospheric CO₂ concentration and temperature, will affect most ecosystems. The varied responses of plants to these aspects of GEC are well documented. As with other key below-ground components of terrestrial ecosystems, the response of the ubiquitous mycorrhizal fungal root symbionts has received limited attention. Most of the research on the effects of GEC on mycorrhizal fungi has been pot-based with a few field (especially monoculture) studies. A major question that arises in all these studies is whether the GEC effects on the mycorrhizal fungi are independent of the effects on their plant hosts. We evaluate the current knowledge on the effects of elevated CO₂ and increased temperature on mycorrhizal fungi and focus on the few available field examples. The value of using long-term and large-scale field experiments is emphasised. We conclude that the laboratory evidence to date shows that the effect of elevated CO₂ on mycorrhizal fungi is dependent on plant growth and that temperature effects seen in the past might have reflected a similar dependence. Therefore, how temperature directly affects mycorrhizal fungi remains unknown. In natural ecosystems, we predict that GEC effects on mycorrhizal fungal communities will be strongly mediated by the effects on plant communities to the extent that community level interactions will prove to be the key mechanism for determining GEC-induced changes in mycorrhizal fungal communities.     

Southern Hemisphere biodiversity and global change: Data gaps and strategies

Long‐term datasets needed to detect the impacts of global change on southern biodiversity are still scarce and often incomplete, challenging adaptation planning and conservation management. Biological data are probably most limited in arid countries and from the oceans, where natural environmental variability (‘noise’) means that long time series are required to detect the ‘signal’ of directional change. Significant national and international investment and collaboration are needed for most southern nations to reliably track biodiversity trends and improve conservation adaptation to rapid climate change. Emerging early warning systems for biodiversity, incorporating regional environmental change drivers, citizen science and regional partnerships, can all help to compensate for existing information gaps and contribute to adaptation planning.     

Prediction uncertainty of environmental change effects on temperate European biodiversity

Observed patterns of species richness at landscape scale (gamma diversity) cannot always be attributed to a specific set of explanatory variables, but rather different alternative explanatory statistical models of similar quality may exist. Therefore predictions of the effects of environmental change (such as in climate or land cover) on biodiversity may differ considerably, depending on the chosen set of explanatory variables. Here we use multimodel prediction to evaluate effects of climate, land-use intensity and landscape structure on species richness in each of seven groups of organisms (plants, birds, spiders, wild bees, ground beetles, true bugs and hoverflies) in temperate Europe. We contrast this approach with traditional best-model predictions, which we show, using cross-validation, to have inferior prediction accuracy. Multimodel inference changed the importance of some environmental variables in comparison with the best model, and accordingly gave deviating predictions for environmental change effects. Overall, prediction uncertainty for the multimodel approach was only slightly higher than that of the best model, and absolute changes in predicted species richness were also comparable. Richness predictions varied generally more for the impact of climate change than for land-use change at the coarse scale of our study. Overall, our study indicates that the uncertainty introduced to environmental change predictions through uncertainty in model selection both qualitatively and quantitatively affects species richness projections.     

Using lichen biomonitoring to assess environmental justice at a neighbourhood level in an industrial area of Northern France

Environmental inequalities are based on the proximity of socio-economically disadvantaged populations to sources of environmental and public health risks, and have recently been extended to environmental contamination. We evaluated such inequalities using a novel approach, at the scale of neighbourhoods in the industrial area of Dunkerque, France, by associating an index of social disadvantage with environmental biomonitoring measurements.A Localised Disadvantage Index (LDI), which characterises the socio-economic status of populations at a neighbourhood level, was developed using an eco-sociological approach. The burdens of 18 trace elements (TE) were recently determined using samples of epiphytic lichens, collected within the study zone. A mean value of TE burden was modelled for each neighbourhood and an integrated index (Mean Impregnation Ratio, MIR) was generated to assess the level of multi-metallic contamination.LDI mapping reveals socio-economic disparities. The neighbourhoods situated near to factories are the most disadvantaged. Environmental maps reveal high contaminations in the vicinity of the industrial zones. The LDI is significantly correlated with the MIR, and with 16 of 18 TE. Significant differences in the level of contamination are observed between high- and low-deprived neighbourhoods.Our results uncover the presence of environmental inequalities. The most disadvantaged populations live in a strongly contaminated environment. We have pioneered the use of biomonitoring data and an integrated index of contamination for the prospection of environmental inequalities.     

附生植物对全球变化的响应及其生物指示作用

附生植物是一类生活在其他植物体上但不从宿主载体吸收营养和水分的特殊植物,其特有的形态结构和生态习性导致了它们对周围环境变化具有高度的敏感性和脆弱性.研究附生植物对全球变化的响应及其生物指示作用,具有重要的指导意义和应用价值.本文概述了附生植物对大气组成变化、气候变化和土地利用/覆盖方式转变等全球变化事件的响应及其生物指...     

The impact of global climate change on tropical forest biodiversity in Amazonia

Aim To model long‐term trends in plant species distributions in response to predicted changes in global climate. Location Amazonia. Methods The impacts of expected global climate change on the potential and realized distributions of a representative sample of 69 individual Angiosperm species in Amazonia were simulated from 1990 to 2095. The climate trend followed the HADCM2GSa1 scenario, which assumes an annual 1% increase of atmospheric CO₂ content with effects mitigated by sulphate forcing. Potential distributions of species in one‐degree grid cells were modelled using a suitability index and rectilinear envelope based on bioclimate variables. Realized distributions were additionally limited by spatial contiguity with, and proximity to, known record sites. A size‐structured population model was simulated for each cell in the realized distributions to allow for lags in response to climate change, but dispersal was not included. Results In the resulting simulations, 43% of all species became non‐viable by 2095 because their potential distributions had changed drastically, but there was little change in the realized distributions of most species, owing to delays in population responses. Widely distributed species with high tolerance to environmental variation exhibited the least response to climate change, and species with narrow ranges and short generation times the greatest. Climate changed most in north‐east Amazonia while the best remaining conditions for lowland moist forest species were in western Amazonia. Main conclusions To maintain the greatest resilience of Amazonian biodiversity to climate change as modelled by HADCM2GSa1, highest priority should be given to strengthening and extending protected areas in western Amazonia that encompass lowland and montane forests.     

Current and future ozone risks to global terrestrial biodiversity and ecosystem processes

Risks associated with exposure of individual plant species to ozone (O₃) are well documented, but implications for terrestrial biodiversity and ecosystem processes have received insufficient attention. This is an important gap because feedbacks to the atmosphere may change as future O₃ levels increase or decrease, depending on air quality and climate policies. Global simulation of O₃ using the Community Earth System Model (CESM) revealed that in 2000, about 40% of the Global 200 terrestrial ecoregions (ER) were exposed to O₃ above thresholds for ecological risks, with highest exposures in North America and Southern Europe, where there is field evidence of adverse effects of O₃, and in central Asia. Experimental studies show that O₃ can adversely affect the growth and flowering of plants and alter species composition and richness, although some communities can be resilient. Additional effects include changes in water flux regulation, pollination efficiency, and plant pathogen development. Recent research is unraveling a range of effects belowground, including changes in soil invertebrates, plant litter quantity and quality, decomposition, and nutrient cycling and carbon pools. Changes are likely slow and may take decades to become detectable. CESM simulations for 2050 show that O₃ exposure under emission scenario RCP8.5 increases in all major biomes and that policies represented in scenario RCP4.5 do not lead to a general reduction in O₃ risks; rather, 50% of ERs still show an increase in exposure. Although a conceptual model is lacking to extrapolate documented effects to ERs with limited or no local information, and there is uncertainty about interactions with nitrogen input and climate change, the analysis suggests that in many ERs, O₃ risks will persist for biodiversity at different trophic levels, and for a range of ecosystem processes and feedbacks, which deserves more attention when assessing ecological implications of future atmospheric pollution and climate change.     

Avoiding a crisis of motivation for ocean management under global environmental change

Climate change and ocean acidification are altering marine ecosystems and, from a human perspective, creating both winners and losers. Human responses to these changes are complex, but may result in reduced government investments in regulation, resource management, monitoring and enforcement. Moreover, a lack of peoples’ experience of climate change may drive some towards attributing the symptoms of climate change to more familiar causes such as management failure. Taken together, we anticipate that management could become weaker and less effective as climate change continues. Using diverse case studies, including the decline of coral reefs, coastal defences from flooding, shifting fish stocks and the emergence of new shipping opportunities in the Arctic, we argue that human interests are better served by increased investments in resource management. But greater government investment in management does not simply mean more of “business‐as‐usual.” Management needs to become more flexible, better at anticipating and responding to surprise, and able to facilitate change where it is desirable. A range of technological, economic, communication and governance solutions exists to help transform management. While not all have been tested, judicious application of the most appropriate solutions should help humanity adapt to novel circumstances and seek opportunity where possible.     

生物多样性适应气候变化的国家政策和措施: 国际经验及启示

气候变化已成为威胁生物多样性及生态系统服务功能的主要因素之一, 许多国家已经意识到必须提高本国生物多样性适应气候变化的能力。一些国家出台了国家战略, 采取增加连通性、改进现有保护区域的管理和恢复措施等基于生态系统的适应措施, 采用跨学科与跨部门协作手段加强生物多样性适应气候变化的监测和评估, 并且从制度和资金等方面加强政策措施的落实。作者对部分发达国家和发展中的生物多样性大国的生物多样性适应气候变化的相关政策和措施进行了梳理, 并结合我国现状提出以下建议: (1)把生物多样性适应气候变化作为国家整体适应战略中的优先措施之一; (2)将提高生物多样性和生态系统的恢复力作为适应气候变化的基础性原则; (3)整合并完善国家生物多样性监测网络, 参考国际通行标准制定信息和数据收集标准, 并且尽快对气候变化下我国生物多样性脆弱性开展全面且持续的评估。     

Climate warming causes photobiont degradation and carbon starvation in a boreal climate sentinel lichen

Premise

The long-term potential for acclimation by lichens to changing climates is poorly known, despite their prominent roles in forested ecosystems. Although often considered “extremophiles,” lichens may not readily acclimate to novel climates well beyond historical norms. In a previous study (Smith et al., 2018), Evernia mesomorpha transplants in a whole-ecosystem climate change experiment showed drastic mass loss after 1 yr of warming and drying; however, the causes of this mass loss were not addressed.

Methods

We examined the causes of this warming-induced mass loss by measuring physiological, functional, and reproductive attributes of lichen transplants.

Results

Severe loss of mass and physiological function occurred above +2°C of experimental warming. Loss of algal symbionts (“bleaching”) and turnover in algal community compositions increased with temperature and were the clearest impacts of experimental warming. Enhanced CO₂ had no significant physiological or symbiont composition effects. The functional loss of algal photobionts led to significant loss of mass and specific thallus mass (STM), which in turn reduced water-holding capacity (WHC). Although algal genotypes remained detectable in thalli exposed to higher stress, within-thallus photobiont communities shifted in composition toward greater diversity.

Conclusions

The strong negative impacts of warming and/or lower humidity on Evernia mesomorpha were driven by a loss of photobiont activity. Analogous to the effects of climate change on corals, the balance of symbiont carbon metabolism in lichens is central to their resilience to changing conditions.     

The integration of biodiversity and climate change: A contextual assessment of the carbon farming initiative

Summary The Carbon Farming Initiative (CFI) allows the creation of tradable Australian Carbon Credit Units (ACCUs) derived from across the ecosystem sector via project‐level baseline and credit activities: it is the first national offset scheme in the world to broadly include farming and forestry projects. Because these activities have the potential to produce both biodiversity and climate change benefits, a crucial outcome is for widespread uptake of the policy. However, the design, complexity and cost of the CFI project development process, and low prices as a result of ACCUs trading in the voluntary market, will all likely militate against this. This article shows how international politics and policy surrounding the Kyoto Protocol have influenced the design of the CFI, with its potential to proliferate complex and narrow methodologies and counter‐productive approaches to integrity standards such as permanence. The article shows that despite the pressing need to integrate biodiversity and climate change considerations as equally important challenges, their global integration remains poorly articulated. Biodiversity considerations are also not integrated into the CFI but, rather, are dealt with indirectly through safeguard measures that avoid perverse incentives and unintended harm, and as an optional co‐benefit via the development of an index. This article suggests that we need to move past the shackles of Kyoto towards streamlined and standardized approaches such as risk‐based assessments and the use of regional baselines. Using regionally specific baselines such as for avoided deforestation would allow landholders to opt‐in to regional‐scale mitigation opportunities. Activities that Australia accounts for, such as reforestation and deforestation, should also be able to opt‐in for coverage under the Clean Energy Act (and out of the voluntary carbon market) to obtain a secure price.     

The ecology of the planktonic diatom Cyclotella and its implications for global environmental change studies

The fossil record of diatoms in lake sediments can be used to assess the effects of climate variability on lake ecosystems if ecological relationships between diatom community structure and environmental parameters are well understood. Cyclotella sensu lato taxa are a key group of diatoms that are frequently dominant members of phytoplankton communities in low‐ to moderate‐productivity lakes. Their relative abundances have fluctuated significantly in palaeolimnological records spanning over a century in arctic, alpine, boreal and temperate lakes. This suggests that these species are sensitive to environmental change and may serve as early indicators of ecosystem effects of global change. Yet patterns of change in Cyclotella species are not synchronous or unidirectional across, or even within, regions, raising the question of how to interpret these widespread changes in diatom community structure. We suggest that the path forward in resolving seemingly disparate records is to identify clearly the autecology of Cyclotella species, notably the role of nutrients, dissolved organic carbon and light, coupled with better consideration of both the mechanisms controlling lake thermal stratification processes and the resulting effects of changing lake thermal regimes on light and nutrients. Here we begin by reviewing the literature on the resource requirements of common Cyclotella taxa, illustrating that many studies reveal the importance of light, nitrogen, phosphorus, and interactions among these resources in controlling relative abundances. We then discuss how these resource requirements can be linked to shifts in limnological processes driven by environmental change, including climate‐driven change in lakewater temperature, thermal stratification and nutrient loading, as well as acidification‐driven shifts in nutrients and water clarity. We examine three case studies, each involving two lakes from the same region that have disparate trends in the relative abundances of the same species, and illustrate how the mechanisms by which these species abundances are changing can be deciphered. Ultimately, changes in resource availability and water clarity are key factors leading to shifts in Cyclotella abundances. Tighter integration of the autecology of this important group of diatoms with environmental change and subsequent alterations in limnological processes will improve interpretations of palaeolimnological records, and clarify the drivers of seemingly disparate patterns in fossil records showing widespread and rapid changes across the northern hemisphere.     

Mean species responses predict effects of environmental change on coexistence

Environmental change research is plagued by the curse of dimensionality: the number of communities at risk and the number of environmental drivers are both large. This raises the pressing question if a general understanding of ecological effects is achievable. Here, we show evidence that this is indeed possible. Using theoretical and simulation-based evidence for bi- and tritrophic communities, we show that environmental change effects on coexistence are proportional to mean species responses and depend on how trophic levels on average interact prior to environmental change. We then benchmark our findings using relevant cases of environmental change, showing that means of temperature optima and of species sensitivities to pollution predict concomitant effects on coexistence. Finally, we demonstrate how to apply our theory to the analysis of field data, finding support for effects of land use change on coexistence in natural invertebrate communities.