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1. A global assessment of environmental and climate influences on wetland macroinvertebrate community structure and function

   https://doi.org/10.1111/gcb.17173  

   Epele, Luis B.; Williams‐Subiza, Emilio A.; Bird, Matthew S.; Boissezon, Aurelie; Boix, Dani; Demierre, Eliane; Fair, Conor G.; García, Patricia E.; Gascón, Stephanie; Grech, Marta G.; et al (February 2024, Global Change Biology)

   Abstract Estimating organisms' responses to environmental variables and taxon associations across broad spatial scales is vital for predicting their responses to climate change. Macroinvertebrates play a major role in wetland processes, but studies simultaneously exploring both community structure and community trait responses to environmental gradients are still lacking. We compiled a global dataset (six continents) from 756 depressional wetlands, including the occurrence of 96 macroinvertebrate families, their phylogenetic tree, and 19 biological traits. Using Bayesian hierarchical joint species distribution models (JSDMs), we estimated macroinvertebrate associations and compared the influences of local and climatic predictors on both individual macroinvertebrate families and their traits. While macroinvertebrate families were mainly related to broad‐scale factors (maximum temperature and precipitation seasonality), macroinvertebrate traits were strongly related to local wetland hydroperiod. Interestingly, macroinvertebrate families and traits both showed positive and negative associations to the same environmental variables. As expected, many macroinvertebrate family occurrences were positively associated with temperature, but a few showed the opposite pattern and were found in cooler or montane regions. We also found that wetland macroinvertebrate communities would likely be affected by changing climates through alterations in traits related to precipitation seasonality, temperature seasonality, and wetland area. Temperature increases may negatively affect collector and shredder functional groups. A decrease in precipitation could lead to reductions in wetland area benefiting drought‐tolerant macroinvertebrates, but it may negatively affect macroinvertebrates lacking those adaptations. Wetland processes may be compromised through broad‐scale environmental changes altering macroinvertebrate family distributions and local hydroperiod shifts altering organism traits. Our complementary family‐based and trait‐based approaches elucidate the complex effects that climate change may produce on wetland ecosystems. 

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2. Zooming Out: Methods and Future Directions in Landscape‐Scale Functional Assessment of Inland Wetlands

   https://doi.org/10.1002/wat2.70044  

   Van_Meter, Kimberly; Delesantro, Joseph; Kolli, Meena Kumari; Basu, Nandita; Lang, Megan; McCarty, Greg; Owen, Sara (January 2026, WIREs Water)

   ABSTRACT Wetlands play a vital role in supporting hydrologic, biogeochemical, and ecological processes across landscapes, yet understanding and quantifying their functional contributions at large spatial scales remains a challenge. In response to increasing demand for regional and national assessments, a growing number of methods have emerged that estimate wetland function using widely available geospatial data. This systematic review describes and evaluates currently available approaches to quantifying wetland function at landscape scales and highlights key lessons for future assessments. We identify two primary methodological categories: classification‐based approaches, such as hydrogeomorphic (HGM) and LLWW (Landscape Position, Landform, Water Flow Path, Waterbody Type) frameworks, which assign functional scores based on mapped wetland class; and indicator‐based approaches, which derive metrics or indices directly linked to functional processes using remote sensing and other spatial data. Across both, we find that validation against field data remains limited, habitat functions are consistently the most difficult to assess, and that many assessments estimate only thepotentialof wetlands to perform specific functions rather than how they are actually functioning under current landscape conditions. At the same time, advances in high‐resolution remote sensing, automation, and ecological modeling are creating new opportunities for more scalable, repeatable, and functionally relevant assessments. Hybrid approaches that bridge classification and indicator methods, and that integrate land‐use and disturbance metrics, represent a promising path toward national‐scale functional assessments. Together, these findings point to a way forward for producing wetland functional assessments that are both scientifically rigorous and actionable for conservation and policy. This article is categorized under:Water and Life > Nature of Freshwater EcosystemsWater and Life > Conservation, Management, and AwarenessScience of Water > Water and Environmental Change 

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3. Setting a reference for wetland carbon: the importance of accounting for hydrology, topography, and natural variability

   https://doi.org/10.1088/1748-9326/acd26a  

   Stewart, Graham A; Kottkamp, Anna I; Williams, Michael R; Palmer, Margaret A (May 2023, Environmental Research Letters)

   Abstract Wetland soils are a key global sink for organic carbon (C) and a focal point for C management and accounting efforts. The ongoing push for wetland restoration presents an opportunity for climate mitigation, but C storage expectations are poorly defined due to a lack of reference information and an incomplete understanding of what drives natural variability among wetlands. We sought to address these shortcomings by (1) quantifying the range of variability in wetland soil organic C (SOC) stocks on a depressional landscape (Delmarva Peninsula, USA) and (2) investigating the role of hydrology and relative topography in explaining variability among wetlands. We found a high degree of variability within individual wetlands and among wetlands with similar vegetation and hydrogeomorphic characteristics. This suggests that uncertainty should be presented explicitly when inferring ecosystem processes from wetland types or land cover classes. Differences in hydrologic regimes, particularly the rate of water level recession, explained some of the variability among wetlands, but relationships between SOC stocks and some hydrologic metrics were eclipsed by factors associated with separate study sites. Relative topography accounted for a similar portion of SOC stock variability as hydrology, indicating that it could be an effective substitute in large-scale analyses. As wetlands worldwide are restored and focus increases on quantifying C benefits, the importance of appropriately defining and assessing reference systems is paramount. Our results highlight the current uncertainty in this process, but suggest that incorporating landscape heterogeneity and drivers of natural variability into reference information may improve how wetland restoration is implemented and evaluated. 

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4. Intrinsic and extrinsic drivers of organic matter processing along phosphorus and salinity gradients in coastal wetlands

   https://doi.org/10.1111/1365-2745.14302  

   Anderson, Kenneth J; Kominoski, John S; Sah, Jay P (March 2024, Journal of Ecology)

   Abstract Climate change is accelerating sea‐level rise and saltwater intrusion in coastal regions world‐wide and interacting with large‐scale changes in species composition in coastal wetlands. Quantifying macrophyte litter breakdown along freshwater‐to‐marine coastal gradients is needed to predict how carbon stores will respond to shifts in both macrophyte communities and water chemistry under changing environmental conditions.To test the interactive drivers of changing species identity and water chemistry, we performed a reciprocal transplant of four macrophyte litter species in seven sites along freshwater‐to‐marine gradients in the Florida Coastal Everglades. We measured surface water chemistry (dissolved organic carbon, total nitrogen and total phosphorus), litter chemistry (% nitrogen, % phosphorus, change in N:P molar ratio, % cellulose and % lignin as proxies for recalcitrance) and litter breakdown rates (k/degree‐day).Direct effects of salinity and surface water nutrients were the strongest drivers ofk, but unexpectedly, litter chemistry did not correlate with litterk. However, salinity strongly correlated with changes in litter chemistry, whereby litter incubated in brackish and marine wetlands was more labile and gained more phosphorus compared with litter in freshwater marshes. Our results suggest that litterkin coastal wetlands is explained by species‐specific interactions among water and litter chemistries. Water nutrient availability was an important predictor of breakdown rates across species, but breakdown rates were only explained by the carbon recalcitrance of litter in the species with the slowest breakdown (Cladium jamaicense), indicating the importance of carbon structure, and species identity on breakdown rates.Synthesis. In oligotrophic ecosystems, nutrients are often the primary driver of organic matter breakdown. However, we found that variation in macrophyte breakdown rates in oligotrophic coastal wetlands was also explained by salinity and associated seawater chemistry, emphasising the need to understand how saltwater intrusion will alter organic matter processing in wetlands. Our results suggest that marine subsidies associated with sea‐level rise have the potential to accelerate leaf litter breakdown. The increase in breakdown rates could either be buffered or increase further as sea‐level rise also shifts macrophyte community composition to more or less recalcitrant species. 

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5. Plant functional traits are dynamic predictors of ecosystem functioning in variable environments

   https://doi.org/10.1111/1365-2745.14197  

   Huxley, Jared D; White, Caitlin T; Humphries, Hope C; Weber, Soren E; Spasojevic, Marko J (December 2023, Journal of Ecology)

   Abstract A central goal at the interface of ecology and conservation is understanding how the relationship between biodiversity and ecosystem function (B–EF) will shift with changing climate. Despite recent theoretical advances, studies which examine temporal variation in the functional traits and mechanisms (mass ratio effects and niche complementarity effects) that underpin the B–EF relationship are lacking.Here, we use 13 years of data on plant species composition, plant traits, local‐scale abiotic variables, above‐ground net primary productivity (ANPP), and climate from the alpine tundra of Colorado (USA) to investigate temporal dynamics in the B–EF relationship. To assess how changing climatic conditions may alter the B–EF relationship, we built structural equation models (SEMs) for 11 traits across 13 years and evaluated the power of different trait SEMs to predict ANPP, as well as the relative contributions of mass ratio effects (community‐weighted mean trait values; CWM), niche complementarity effects (functional dispersion; FDis) and local abiotic variables. Additionally, we coupled linear mixed effects models with Multimodel inference methods to assess how inclusion of trait–climate interactions might improve our ability to predict ANPP through time.In every year, at least one SEM exhibited good fit, explaining between 19.6% and 57.2% of the variation in ANPP. However, the identity of the trait which best explained ANPP changed depending on winter precipitation, with leaf area, plant height and foliar nitrogen isotope content (δ¹⁵N) SEMs performing best in high, middle and low precipitation years, respectively. Regardless of trait identity, CWMs exerted a stronger influence on ANPP than FDis and total biotic effects were always greater than total abiotic effects. Multimodel inference reinforced the results of SEM analysis, with the inclusion of climate–trait interactions marginally improving our ability to predict ANPP through time.Synthesis. Our results suggest that temporal variation in climatic conditions influences which traits, mechanisms and abiotic variables were most responsible for driving the B–EF relationship. Importantly, our findings suggest that future research should consider temporal variability in the B–EF relationship, particularly how the predictive power of individual functional traits and abiotic variables may fluctuate as conditions shift due to climate change. 

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