Global Change Biology最新文献

Climate change mitigation and biodiversity loss are closely linked challenges, yet agricultural strategies often address them separately. Focusing on rice farming, this article shows that widely promoted water-saving practices can reduce greenhouse gas emissions but may also harm freshwater biodiversity that depends on flooded fields. We highlight alternative management approaches and the need for spatially and seasonally targeted strategies that balance climate goals, biodiversity conservation, and food production.

Associations between feather mosses and cyanobacteria are crucial sources of new biologically available nitrogen (N) in arctic and subarctic ecosystems. The physiology of both mosses and cyanobacteria is strongly influenced by environmental factors such as temperature and moisture, which directly affect N₂ fixation rates. These associations may be threatened by climate change, since it leads to warmer and drier conditions in polar regions. In this study, we investigated the N₂-fixing microbial communities associated with two common feather mosses across a precipitation gradient in the subarctic tundra, followed by a temperature and moisture experiment. Using acetylene reduction assays, nifH gene sequencing and qPCR, we evaluated how shifts in temperature and moisture influence nitrogenase activity and N₂-fixing community structure. Our results showed that N₂ fixation was highest in sites with greater precipitation and increased with both temperature and moisture. Cyanobacteria dominated N₂-fixing communities, but currently unclassified bacteria also seemed to play a significant role, particularly at higher temperatures. The number of cyanobacterial nifH copies tended to remain stable or decrease with temperature, while the relative abundance of unclassified bacteria increased. These findings suggest that the N₂-fixing activity, abundance, and diversity of cyanobacteria associated with feather mosses in the subarctic will decline under warmer and drier conditions, potentially leading to a shift in the composition of feather moss-associated microbial communities in a warmer Arctic, with potential consequences for N input into the ecosystem.

Accelerated warming, particularly in mountain regions, is altering plant phenology across ecosystems. However, the extent of these changes varies among species and regions. While phenophases in plant compartments such as leaves or flowers are relatively easy to observe, monitoring xylem phenology remains challenging due to the labour-intensive methods required to capture intra-annual growth dynamics. Here, we adopted an indirect retrospective approach to infer cambial phenology by analysing the timing and occurrence of frost damage in the growth rings of three Alpine conifer species. Increment cores were collected from 4481 individuals (1897 Larix decidua Mill., 980 Picea abies L. Karst., and 1604 Pinus cembra L.) at two high-elevation sites in the Eastern Alps. Frost rings were identified, dated, and compared with long-term (1774–2020) daily temperature records to determine their timing, using the 1.7°C threshold for cambial activity onset and subsequent episodes when minimum temperatures dropped below 0°C. We found that the cold spells responsible for frost ring formation remained consistent, typically involving temperatures dropping below freezing for an average of 4–5 consecutive days. However, the timing of frost ring formation, and thus cambial onset, has shifted over the past 200 years with no significant differences across taxa. This shift corresponds to about 7 days earlier per century or per °C of warming and is notably smaller than phenological shifts reported for other plant compartments in the same region. Given the critical role of cambial activity in forest carbon dynamics, these findings can help refine global vegetation models and improve predictions of ecosystem responses to climate change.

Understanding how marine habitats are changing with a warming Arctic is essential for conservation, management, and adaptation strategies bearing tangible consequences for Arctic communities and ecosystems. Ringed seals and bearded seals rely on specific ice and snow conditions to support critical life history events affecting survival and reproduction. Here, we develop a panarctic habitat suitability model linking life events and environmental conditions. With Earth System Models, we simulate habitat over 1850–2100, revealing a relatively stable past habitat contrasting with rapid regional shifts in contemporary simulations and future projections. Core historical habitats are projected to decline, but two regions arise as potential refugia—the East Siberian Sea and Canadian Arctic Archipelago—that could support ice seal populations towards 2100. These findings underscore the importance of refined monitoring and regional conservation strategies for ringed and bearded seals, and their unique ecosystem.

Drought is expected to increase in frequency and severity due to climate change, highlighting the urgency of understanding drought impacts on wildlife across geographies and taxonomic groups. We conducted a review of peer-reviewed articles from 1982 to 2024, focusing on the impacts of anomalous drought on terrestrial vertebrates. We recorded 3324 total wildlife responses, 188 from single-species studies and 3136 from multi-species studies. Within single-species studies, 66% of responses were negative, 32% were unclear, and 2% were positive, illustrating the widespread threat of increasing drought to global wildlife. Within multi-species studies, 24% of responses were negative, and 5% were positive. Notably, 71% of responses within multi-species papers were categorized as “unclear”, highlighting the need for additional investigation and the complexity of synthesizing a diverse literature. Drought impacts are not evenly tested across taxa, with birds being the most frequently studied (51% of documented responses), followed by mammals (28%), amphibians (16%), and reptiles (5%). Geographically, studies tended to occur most often where recent increases in anomalous drought have been observed (e.g., the Southwestern United States, South Africa, and Southeastern Australia). The sophistication of how drought is measured has increased over time, whereby studies increasingly defined drought as an anomalous event in comparison to a long-term average through the use of drought indices, rather than as a short-term weather event. However, we did not see consistency in indices used across the literature, which has the potential to present challenges for interpretation and synthesis. This review summarizes the predominantly negative impacts of drought on terrestrial vertebrates and the growing challenge of conserving wildlife in a changing world, while also highlighting gaps in our understanding of drought-wildlife relationships that can guide future research.

The fate of carbon stored in Arctic peatlands remains uncertain because of the complex nature of the effects of climate change on permafrost and peatland carbon cycling. Expansion and/or shrinkage of Arctic peatlands under climate change also remain unknown due to lack of ground data and difficulties detecting changes in the extent of these ecosystems, meaning that land surface model predictions currently inadequately quantify Arctic terrestrial carbon storage changes. Pan-Arctic shifts in peatland extent would profoundly change the fate of carbon in the terrestrial Arctic. Here, we tackle this knowledge gap by answering three main questions: (a) has lateral expansion occurred in Arctic peatlands as a response to recent warming? (b) if so, how fast has this occurred? (c) how does the response vary regionally? To answer these, we collected a dataset (12 peatland sites, 91 peat cores) combining peat cores collected across two latitudinal (north–south) transects: one in the European Arctic and one in the Canadian Arctic. In each region, we selected three peatland sites, with cores collected from transects spanning the peat-edge to the peat-centre. Our large-scale dataset shows that peatlands have expanded, often rapidly, with some rates exceeding ~1 m per year since 1950 AD. This rapid expansion has occurred during a period of widespread Arctic warming and is still ongoing: two thirds (8/12) of our peatland sites evidence new peat formation after ~1990 AD based on age-depth models constrained by ¹⁴C and ²¹⁰Pb dating. Given that our sites comprise a broad range of Arctic conditions, we expect peatland expansion to be a pan-Arctic phenomenon. Within specific regions, there are constraints on peat expansion including topographical limits, but we present the basis for future work to estimate pan-Arctic peatland expansion, plus the associated carbon cycle implications under future climate change.

Salt marshes play a vital role in the biogeochemistry of coastal zones, yet the biophysical controls on CO₂ exchange with the atmosphere, or net ecosystem exchange (NEE, positive upwards) remain poorly quantified. We investigated a Spartina alterniflora monoculture salt marsh on the eastern shore of Virginia, United States, by estimating half-hourly NEE from March 2016 to February 2017 using the eddy-covariance method. Maximum marsh–atmosphere CO₂ exchanges occurred during June and July when hourly averaged NEE values reached −10.0 ± 2.5 μmol CO₂ m⁻² s⁻¹ (mean ±1 standard deviation). During the most productive time of the year, a tidal inundation of 0.7 m reduced daytime CO₂ assimilation and nighttime CO₂ release to the atmosphere by 5.0 ± 1.2 μmol CO₂ m⁻² s⁻¹ and 3.0 ± 0.7 μmol CO₂ m⁻² s⁻¹, respectively. Diffuse photosynthetically active radiation (PAR) conditions promoted quantum use efficiencies (α) of the ecosystem that were approximately three times greater than under direct PAR conditions (α_Cloudy = 0.012 ± 0.004 versus α_Clear = 0.004 ± 0.001 mol CO₂ per (mol photons)). Under diffuse light, NEE increased more rapidly with PAR and photo-saturation occurred at higher PAR levels compared to clear-sky conditions. On average, under the influence of diffuse light, the assimilation of CO₂ increased by 30% relative to equivalent PAR levels under direct sunlight. During March 2016 to February 2017 the marsh exchanged −269.1 ± 9.1 g of carbon per m² with the atmosphere. The findings demonstrate that tides and light quality are key regulators of carbon cycling in tidal marshes. These factors should be incorporated into models of tidal marsh biogeochemistry, particularly as both are undergoing rapid changes due to sea level rise and atmospheric warming.