| 401. |
- Wilson, Oliver J, et al.
(författare)
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Cold spot microrefugia hold the key to survival for Brazil's Critically Endangered Araucaria tree
- 2019
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 25:12, s. 4339-4351
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Tidskriftsartikel (refereegranskat)abstract
- Brazil's Araucaria tree (Araucaria angustifolia) is an iconic living fossil and a defining element of the Atlantic Forest global biodiversity hotspot. But despite more than two millennia as a cultural icon in southern Brazil, Araucaria is on the brink of extinction, having lost 97% of its extent to 20th-century logging. Although logging is now illegal, 21st-century climate change constitutes a new-but so far unevaluated-threat to Araucaria's future survival. We use a robust ensemble modelling approach, using recently developed climate data, high-resolution topography and fine-scale vegetation maps, to predict the species' response to climate change and its implications for conservation on meso- and microclimate scales. We show that climate-only models predict the total disappearance of Araucaria's most suitable habitat by 2070, but incorporating topographic effects allows potential highland microrefugia to be identified. The legacy of 20th-century destruction is evident-more than a third of these likely holdouts have already lost their natural vegetation-and 21st-century climate change will leave just 3.5% of remnant forest and 28.4% of highland grasslands suitable for Araucaria. Existing protected areas cover only 2.5% of the surviving microrefugia for this culturally important species, and none occur in any designated indigenous territory. Our results suggest that anthropogenic climate change is likely to commit Araucaria to a second consecutive century of significant losses, but targeted interventions could help ensure its survival in the wild.
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| 402. |
- Xia, Shaopan, et al.
(författare)
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Distribution, sources, and decomposition of soil organic matter along a salinity gradient in estuarine wetlands characterized by C:N ratio, δ13C-δ15N, and lignin biomarker
- 2021
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 27:2, s. 417-434
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Tidskriftsartikel (refereegranskat)abstract
- Despite increasing recognition of the critical role of coastal wetlands in mitigating climate change, sea‐level rise, and salinity increase, soil organic carbon (SOC) sequestration mechanisms in estuarine wetlands remain poorly understood. Here, we present new results on the source, decomposition, and storage of SOC in estuarine wetlands with four vegetation types, including single Phragmites australis (P, habitat I), a mixture of P. australis and Suaeda salsa (P + S, habitat II), single S. salsa (S, habitat III), and tidal flat (TF, habitat IV) across a salinity gradient. Values of δ13C increased with depth in aerobic soil layers (0–40 cm) but slightly decreased in anaerobic soil layers (40–100 cm). The δ15N was significantly enriched in soil organic matter at all depths than in the living plant tissues, indicating a preferential decomposition of 14N‐enriched organic components. Thus, the kinetic isotope fractionation during microbial degradation and the preferential substrate utilization are the dominant mechanisms in regulating isotopic compositions in aerobic and anaerobic conditions, respectively. Stable isotopic (δ13C and δ15N), elemental (C and N), and lignin composition (inherited (Ad/Al)s and C/V) were not completely consistent in reflecting the differences in SOC decomposition or accumulation among four vegetation types, possibly due to differences in litter inputs, root distributions, substrate quality, water‐table level, salinity, and microbial community composition/activity. Organic C contents and storage decreased from upstream to downstream, likely due to primarily changes in autochthonous sources (e.g., decreased onsite plant biomass input) and allochthonous materials (e.g., decreased fluvially transported upland river inputs, and increased tidally induced marine algae and phytoplankton). Our results revealed that multiple indicators are essential to unravel the degree of SOC decomposition and accumulation, and a combination of C:N ratios, δ13C, δ15N, and lignin biomarker provides a robust approach to decipher the decomposition and source of sedimentary organic matter along the river‐estuary‐ocean continuum.
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| 403. |
- Xia, Shaopan, et al.
(författare)
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Storage, patterns and influencing factors for soil organic carbon in coastal wetlands of China
- 2022
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 28:20, s. 6065-6085
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Tidskriftsartikel (refereegranskat)abstract
- Soil organic carbon (SOC) in coastal wetlands, also known as "blue C," is an essential component of the global C cycles. To gain a detailed insight into blue C storage and controlling factors, we studied 142 sites across ca. 5000 km of coastal wetlands, covering temperate, subtropical, and tropical climates in China. The wetlands represented six vegetation types (Phragmites australis, mixed of P. australis and Suaeda, single Suaeda, Spartina alterniflora, mangrove [Kandelia obovata and Avicennia marina], tidal flat) and three vegetation types invaded by S. alterniflora (P. australis, K. obovata, A. marina). Our results revealed large spatial heterogeneity in SOC density of the top 1-m ranging 40-200 Mg C ha(-1), with higher values in mid-latitude regions (25-30 degrees N) compared with those in both low- (20 degrees N) and high-latitude (38-40 degrees N) regions. Vegetation type influenced SOC density, with P. australis and S. alterniflora having the largest SOC density, followed by mangrove, mixed P. australis and Suaeda, single Suaeda and tidal flat. SOC density increased by 6.25 Mg ha(-1) following S. alterniflora invasion into P. australis community but decreased by 28.56 and 8.17 Mg ha(-1) following invasion into K. obovata and A. marina communities. Based on field measurements and published literature, we calculated a total inventory of 57 x 10(6) Mg C in the top 1-m soil across China's coastal wetlands. Edaphic variables controlled SOC content, with soil chemical properties explaining the largest variance in SOC content. Climate did not control SOC content but had a strong interactive effect with edaphic variables. Plant biomass and quality traits were a minor contributor in regulating SOC content, highlighting the importance of quantity and quality of OC inputs and the balance between production and degradation within the coastal wetlands. These findings provide new insights into blue C stabilization mechanisms and sequestration capacity in coastal wetlands.
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| 404. |
- Xu, Y. S., et al.
(författare)
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Variations in leaf anatomical characteristics drive the decrease of mesophyll conductance in poplar under elevated ozone
- 2023
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 29:10, s. 2804-2823
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Tidskriftsartikel (refereegranskat)abstract
- Decline in mesophyll conductance (g(m)) plays a key role in limiting photosynthesis in plants exposed to elevated ozone (O-3). Leaf anatomical traits are known to influence g(m), but the potential effects of O-3-induced changes in leaf anatomy on g(m) have not yet been clarified. Here, two poplar clones were exposed to elevated O-3. The effects of O-3 on the photosynthetic capacity and anatomical characteristics were assessed to investigate the leaf anatomical properties that potentially affect g(m). We also conducted global meta-analysis to explore the general response patterns of g(m) and leaf anatomy to O-3 exposure. We found that the O-3-induced reduction in g(m) was critical in limiting leaf photosynthesis. Changes in liquid-phase conductance rather than gas-phase conductance drive the decline in g(m) under elevated O-3,O- and this effect was associated with thicker cell walls and smaller chloroplast sizes. The effects of O-3 on palisade and spongy mesophyll cell traits and their contributions to g(m) were highly genotype-dependent. Our results suggest that, while anatomical adjustments under elevated O-3 may contribute to defense against O-3 stress, they also cause declines in g(m) and photosynthesis. These results provide the first evidence of anatomical constraints on g(m) under elevated O-3.
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| 405. |
- Ylänne, Henni, et al.
(författare)
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Reindeer control over subarctic treeline alters soil fungal communities with potential consequences for soil carbon storage
- 2021
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 27:18, s. 4254-4268
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Tidskriftsartikel (refereegranskat)abstract
- The climate-driven encroachment of shrubs into the Arctic is accompanied by shifts in soil fungal communities that could contribute to a net release of carbon from tundra soils. At the same time, arctic grazers are known to prevent the establishment of deciduous shrubs and, under certain conditions, promote the dominance of evergreen shrubs. As these different vegetation types associate with contrasting fungal communities, the belowground consequences of climate change could vary among grazing regimes. Yet, at present, the impact of grazing on soil fungal communities and their links to soil carbon have remained speculative. Here we tested how soil fungal community composition, diversity and function depend on tree vicinity and long-term reindeer grazing regime and assessed how the fungal communities relate to organic soil carbon stocks in an alpine treeline ecotone in Northern Scandinavia. We determined soil carbon stocks and characterized soil fungal communities directly underneath and >3 m away from mountain birches (Betula pubescens ssp. czerepanovii) in two adjacent 55-year-old grazing regimes with or without summer grazing by reindeer (Rangifer tarandus). We show that the area exposed to year-round grazing dominated by evergreen dwarf shrubs had higher soil C:N ratio, higher fungal abundance and lower fungal diversity compared with the area with only winter grazing and higher abundance of mountain birch. Although soil carbon stocks did not differ between the grazing regimes, stocks were positively associated with root-associated ascomycetes, typical to the year-round grazing regime, and negatively associated with free-living saprotrophs, typical to the winter grazing regime. These findings suggest that when grazers promote dominance of evergreen dwarf shrubs, they induce shifts in soil fungal communities that increase soil carbon sequestration in the long term. Thus, to predict climate-driven changes in soil carbon, grazer-induced shifts in vegetation and soil fungal communities need to be accounted for.
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| 406. |
- Yu, Zhen, et al.
(författare)
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Natural forests promote phosphorus retention in soil
- 2022
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 28:4, s. 1678-1689
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Tidskriftsartikel (refereegranskat)abstract
- Soil phosphorus (P) availability often limits plant productivity. Classical theories suggest that total P content declines at the temporal scale of pedogenesis, and ecosystems develop toward the efficient use of scarce P during succession. However, the trajectory of ecosystem P within shorter time scales of succession remains unclear. We analyzed changes to P pools at the early (I), middle (II), and late (III) stages of growth of plantation forests (PFs) and the successional stages of natural forests (NFs) at 1969 sites in China. We found significantly lower P contents at later growth stages compared to earlier ones in the PF (p < .05), but higher contents at late successional stages than in earlier stages in the NF (p < .05). Our results indicate that increasing P demand of natural vegetation during succession, may raise, retain, and accumulate P from deeper soil layers. In contrast, ecosystem P in PF was depleted by the more rapidly increasing demand outpacing the development of a P-efficient system. We advocate for more studies to illuminate the mechanisms for determining the divergent changes, which would improve forest management and avoid the vast degradation of PF ecosystems suffering from the ongoing depletion of P.
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| 407. |
- Zabel, Florian, et al.
(författare)
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Large potential for crop production adaptation depends on available future varieties
- 2021
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 27:16, s. 3870-3882
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Tidskriftsartikel (refereegranskat)abstract
- Climate change affects global agricultural production and threatens food security. Faster phenological development of crops due to climate warming is one of the main drivers for potential future yield reductions. To counter the effect of faster maturity, adapted varieties would require more heat units to regain the previous growing period length. In this study, we investigate the effects of variety adaptation on global caloric production under four different future climate change scenarios for maize, rice, soybean, and wheat. Thereby, we empirically identify areas that could require new varieties and areas where variety adaptation could be achieved by shifting existing varieties into new regions. The study uses an ensemble of seven global gridded crop models and five CMIP6 climate models. We found that 39% (SSP5-8.5) of global cropland could require new crop varieties to avoid yield loss from climate change by the end of the century. At low levels of warming (SSP1-2.6), 85% of currently cultivated land can draw from existing varieties to shift within an agro-ecological zone for adaptation. The assumptions on available varieties for adaptation have major impacts on the effectiveness of variety adaptation, which could more than half in SSP5-8.5. The results highlight that region-specific breeding efforts are required to allow for a successful adaptation to climate change.
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| 408. |
- Zelnik, Yuval
(författare)
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Thermal mismatches in biological rates determine trophic control and biomass distribution under warming
- 2021
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 27, s. 257-269
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Tidskriftsartikel (refereegranskat)abstract
- Temperature has numerous effects on the structure and dynamics of ecological communities. Yet, there is no general trend or consensus on the magnitude and directions of these effects. To fill this gap, we propose a mechanistic framework based on key biological rates that predicts how temperature influences biomass distribution and trophic control in food webs. We show that these predictions arise from thermal mismatches between biological rates and across trophic levels. We couple our theory with experimental data for a wide range of species and find that warming should lead to top-heavier terrestrial food chains and stronger top-down control in aquatic environments. We then derive predictions for the effects of temperature on herbivory and validate them with data on stream grazers. Our study provides a mechanistic explanation of thermal effects on consumer-resource systems which is crucial to better understand the biogeography and the consequences of global warming on trophic dynamics.
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| 409. |
- Zhan, Jiasui, et al.
(författare)
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Climate change accelerates local disease extinction rates in a long-term wild host-pathogen association
- 2018
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 24:8, s. 3526-3536
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Tidskriftsartikel (refereegranskat)abstract
- Pathogens are a significant component of all plant communities. In recent years, the potential for existing and emerging pathogens of agricultural crops to cause increased yield losses as a consequence of changing climatic patterns has raised considerable concern. In contrast, the response of naturally occurring, endemic pathogens to a warming climate has received little attention. Here, we report on the impact of a signature variable of global climate change - increasing temperature - on the long-term epidemiology of a natural host-pathogen association involving the rust pathogen Triphragmium ulmariae and its host plant Filipendula ulmaria. In a host-pathogen metapopulation involving approximately 230 host populations growing on an archipelago of islands in the Gulf of Bothnia we assessed changes in host population size and pathogen epidemiological measures over a 25-year period. We show how the incidence of disease and its severity declines over that period and most importantly demonstrate a positive association between a long-term trend of increasing extinction rates in individual pathogen populations of the metapopulation and increasing temperature. Our results are highly suggestive that changing climatic patterns, particularly mean monthly growing season (April-November) temperature, are markedly influencing the epidemiology of plant disease in this host-pathogen association. Given the important role plant pathogens have in shaping the structure of communities, changes in the epidemiology of pathogens have potentially far-reaching impacts on ecological and evolutionary processes. For these reasons, it is essential to increase understanding of pathogen epidemiology, its response to warming, and to invoke these responses in forecasts for the future.
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| 410. |
- Zhang, Huan, et al.
(författare)
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Life-history traits buffer against heat wave effects on predator-prey dynamics in zooplankton
- 2018
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Ingår i: Global Change Biology. - : WILEY. - 1354-1013 .- 1365-2486. ; 24:10, s. 4747-4757
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Tidskriftsartikel (refereegranskat)abstract
- In addition to an increase in mean temperature, extreme climatic events, such as heat waves, are predicted to increase in frequency and intensity with climate change, which are likely to affect organism interactions, seasonal succession, and resting stage recruitment patterns in terrestrial as well as in aquatic ecosystems. For example, freshwater zooplankton with different life-history strategies, such as sexual or parthenogenetic reproduction, may respond differently to increased mean temperatures and rapid temperature fluctuations. Therefore, we conducted a long-term (18months) mesocosm experiment where we evaluated the effects of increased mean temperature (4 degrees C) and an identical energy input but delivered through temperature fluctuations, i.e., as heat waves. We show that different rotifer prey species have specific temperature requirements and use limited and species-specific temperature windows for recruiting from the sediment. On the contrary, co-occurring predatory cyclopoid copepods recruit from adult or subadult resting stages and are therefore able to respond to short-term temperature fluctuations. Hence, these different life-history strategies affect the interactions between cyclopoid copepods and rotifers by reducing the risk of a temporal mismatch in predator-prey dynamics in a climate change scenario. Thus, we conclude that predatory cyclopoid copepods with long generation time are likely to benefit from heat waves since they rapidly wake up even at short temperature elevations and thereby suppress fast reproducing prey populations, such as rotifers. In a broader perspective, our findings suggest that differences in life-history traits will affect predator-prey interactions, and thereby alter community dynamics, in a future climate change scenario.
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