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1. Macrophyte and microbial mat biomass co-variation along a hydrologic gradient and response to a removal experiment in temporary wetlands Everglades, FL, USA, February 2003 – November 2006

   https://doi.org/10.6073/pasta/01ef607bc7090c3488e5bcb7475847e9  

   Kleindl, Paige Marie; Gaiser, Evelyn; Wachnicka, Anna; Sah, Jay; Ross, Michael (January 2024, Environmental Data Initiative)

   This data package encompasses hydrologic variables, soil depth, hydrologically-regulated macrophyte community types, macrophyte biomass and community structure, and microbial mat biomass that was collected in two observational surveys and one in-situ experimental manipulation in six temporary wetland regions located in the Everglades, FL, USA. The goal of this project was to examine the co-variation in macrophyte and microbial mat biomass along the hydrologic gradient present across wetland regions and to determine the type and strength of interactions occurring between the two communities, which was tested using a biomass (macrophyte or microbial mat) removal experiment. The census observational survey took place at 140 sites from 2003-04-09 to 2004-05-26, which were randomly distributed across the hydrologic gradient present across the six temporary wetland regions. The transect observational survey occurred along six transects and each was deliberately established along the present hydrologic gradient within each region; a total of 254 sites were sampled from 2003-02-19 to 2005-03-04. The experiment took place at three temporary wetland sites with contrasting hydroperiods (3 – 6 months), and four transects were established per site with 24 pairs of control and treatment plots per transect. The removal treatment occurred one year before data collection, and data collection occurred from 2004-06-20 to 2006-11-25. The package includes six datasets, one R code file, and two shape files associated with the R code. Data collection for all datasets is complete. FCE1274_Census_Survey includes hydrologically-regulated macrophyte community type classifications, macrophyte biomass, microbial mat ash-free dry mass, mean soil depth, water depth, mean annual hydroperiod, and vegetation-inferred hydroperiod; each site was sampled once during the survey period and a subset of sites were sampled each year. FCE1274_Transect_Survey includes macrophyte community type classifications, macrophyte biomass, microbial mat ash-free dry mass, mean soil depth, water depth, mean annual hydroperiod, and vegetation-inferred hydroperiod. Each site was sampled once during the survey period; all sites along each transect were sampled before moving to the next transect. FCE1274_Removal_Experiment includes total macrophyte biomass, live macrophyte biomass, dead macrophyte biomass, and live macrophyte stem density within each microbial mat removal control and treatment plot along each transect at all three sites. Microbial mat dry mass, microbial mat ash-free dry mass, microbial mat chlorophyll-a concentration, and microbial mat organic content for each macrophyte removal control and treatment plot along each transect at all three sites are included as well. Data was collected once from each plot during the data collection period, and one pair of macrophyte removal plots and microbial mat removal plots were randomly sampled on a bimonthly basis until all plots had been sampled. FCE1274_Removal_Experiment_Macrophyte_Biomass includes total macrophyte biomass for each macrophyte species found within each microbial mat removal control and treatment plot along each transect at all three sites. Data was collected once from each plot during the data collection period, and one pair of microbial mat removal plots were randomly sampled on a bimonthly basis until all plots had been sampled. FCE1274_Removal_Experiment_Macrophyte_Density includes total macrophyte stem density for each macrophyte species found within each microbial mat removal control and treatment plot along each transect at all three sites. Data was collected once from each plot during the data collection period, and one pair of microbial mat removal plots were randomly sampled on a bimonthly basis until all plots had been sampled. FCE1274_Removal_Experiment_Macrophyte_Codes includes the taxon codes assigned to each macrophyte species identified in the FCE1274_Removal_Experiment_Macrophyte_Biomass and FCE1274_Removal_Experiment_Macrophyte_Density datasets. 

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2. Active restoration increases tree species richness and recruitment of large‐seeded taxa after 16–18 years

   https://doi.org/10.1002/eap.3053  

   Schubert, Spencer_C; Zahawi, Rakan_A; Oviedo‐Brenes, Federico; Rosales, Juan_Abel; Holl, Karen_D (November 2024, Ecological Applications)

   Abstract Tropical forest restoration presents a potential lifeline to mitigate climate change and biodiversity crises in the Anthropocene. Yet, the extent to which human interventions, such as tree planting, accelerate the recovery of mature functioning ecosystems or redirect successional trajectories toward novel states remains uncertain due to a lack of long‐term experiments. In 2004–2006, we established three 0.25‐ha plots at 10 sites in southern Costa Rica to test three forest restoration approaches: natural regeneration (no planting), applied nucleation (planting in patches), and plantation (full planting). In a comprehensive survey after 16–18 years of recovery, we censused >80,000 seedlings, saplings, and trees from at least 255 species across 26 restoration plots (nine natural regeneration, nine applied nucleation, eight plantation) and six adjacent reference forests to evaluate treatment effects on recruitment patterns and community composition. Both applied nucleation and plantation treatments resulted in significantly elevated seedling and sapling establishment and more predictable community composition compared with natural regeneration. Similarity of vegetation composition to reference forest tended to scale positively with treatment planting intensity. Later‐successional species with seeds ≥5 mm had significantly greater seedling and sapling abundance in the two planted treatments, and plantation showed similar recruitment densities of large‐seeded (≥10 mm) species to reference forest. Plantation tended toward a lower abundance of early‐successional recruits than applied nucleation. Trees (≥5 cm dbh) in all restoration treatments continued to be dominated by a few early‐successional species and originally transplanted individuals. Seedling recruits of planted taxa were more abundant in applied nucleation than the other treatments though few transitioned into the sapling layer. Overall, our findings show that active tree planting accelerates the establishment of later‐successional trees compared with natural regeneration after nearly two decades. While the apparent advantages of higher density tree planting on dispersal and understory establishment of larger seeded, later‐successional species recruitment is notable, more time is needed to assess whether these differences will persist and transition to the more rapid development of a mature later‐successional canopy. Our results underscore the need for ecological restoration planning and monitoring that targets biodiversity recovery over multiple decades. 

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3. A global meta-analysis on the drivers of salt marsh planting success and implications for ecosystem services

   https://doi.org/10.1038/s41467-024-47769-5  

   Liu, Zezheng; Fagherazzi, Sergio; He, Qiang; Gourgue, Olivier; Bai, Junhong; Liu, Xinhui; Miao, Chiyuan; Hu, Zhan; Cui, Baoshan (December 2024, Nature Communications)

   Abstract Planting has been widely adopted to battle the loss of salt marshes and to establish living shorelines. However, the drivers of success in salt marsh planting and their ecological effects are poorly understood at the global scale. Here, we assemble a global database, encompassing 22,074 observations reported in 210 studies, to examine the drivers and impacts of salt marsh planting. We show that, on average, 53% of plantings survived globally, and plant survival and growth can be enhanced by careful design of sites, species selection, and novel planted technologies. Planting enhances shoreline protection, primary productivity, soil carbon storage, biodiversity conservation and fishery production (effect sizes = 0.61, 1.55, 0.21, 0.10 and 1.01, respectively), compared with degraded wetlands. However, the ecosystem services of planted marshes, except for shoreline protection, have not yet fully recovered compared with natural wetlands (effect size = −0.25, 95% CI −0.29, −0.22). Fortunately, the levels of most ecological functions related to climate change mitigation and biodiversity increase with plantation age when compared with natural wetlands, and achieve equivalence to natural wetlands after 5–25 years. Overall, our results suggest that salt marsh planting could be used as a strategy to enhance shoreline protection, biodiversity conservation and carbon sequestration. 

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4. What’s Going on Down There? Impacts of Long-Term Elevated CO2 and Community Composition on Components of Below-Ground Biomass in a Chesapeake Bay Saltmarsh

   https://doi.org/10.3390/hydrobiology4010008  

   Collin, Rachel; Drake, Bert G; Megonigal, J Patrick (March 2025, Hydrobiology)

   Roots and rhizomes play diverse roles in the response of coastal wetland ecosystems to climate change through hydrobiogeomorphic and biogeochemical processes. The accumulation of living and dead belowground biomass contributes significantly to surface elevation gain, redox status through root oxygen loss and exudates, and plant transport of greenhouse gases to the atmosphere. Yet, responses of belowground biomass to global climate stressors are difficult to measure and remain poorly understood. Here, we report on the response of individual components of belowground biomass to 12 years of CO2 enrichment in a temperate tidal marsh. In both a community initially dominated by the C3 species Schoenoplectus americanus and another initially dominated by the C4 species Spartina patens, elevated CO2 increased total belowground biomass and subtly altered depth distributions of some components. In the Spartina community, this effect was the result of the direct effects of CO2 on plant biomass allocation, while any direct response in the Schoenoplectus community was difficult to detect because of changes in the relative abundance of C3 versus C4 species. In the Schoenoplectus community, belowground biomass was positively related to S. americanus stem density. Compared to the C4 community, the Schoenoplectus community had higher root and rhizome biomass and deeper rhizomes. These results highlight the importance of community composition and plant functional traits in understanding ecosystem- and community-scale responses to elevated CO2 and their potential impacts on marsh elevation. 

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5. Legacy Phosphorus and Ecosystem Memory Control Future Water Quality in a Eutrophic Lake

   https://doi.org/10.1029/2023JG007620  

   Hanson, P. C.; Ladwig, R.; Buelo, C.; Albright, E. A.; Delany, A. D.; Carey, C. C. (November 2023, Journal of Geophysical Research: Biogeosciences)

   Abstract Lake water clarity, phytoplankton biomass, and hypolimnetic oxygen concentration are metrics of water quality that are highly degraded in eutrophic systems. Eutrophication is linked to legacy nutrients stored in catchment soils and in lake sediments. Long lags in water quality improvement under scenarios of nutrient load reduction to lakes indicate an apparent ecosystem memory tied to the interactions between water biogeochemistry and lake sediment nutrients. To investigate how nutrient legacies and ecosystem memory control lake water quality dynamics, we coupled nutrient cycling and lake metabolism in a model to recreate long‐term water quality of a eutrophic lake (Lake Mendota, Wisconsin, USA). We modeled long‐term recovery of water quality under scenarios of nutrient load reduction and found that the rates and patterns of water quality improvement depended on changes in phosphorus (P) and organic carbon storage in the water column and sediments. Through scenarios of water quality improvement, we showed that water quality variables have distinct phases of change determined by the turnover rates of storage pools—an initial and rapid water quality improvement due to water column flushing, followed by a much longer and slower improvement as sediment P pools were slowly reduced. Water clarity, phytoplankton biomass, and hypolimnetic dissolved oxygen differed in their time responses. Water clarity and algal biomass improved within years of nutrient reductions, but hypolimnetic oxygen took decades to improve. Even with reduced catchment loading, recovery of Lake Mendota to a mesotrophic state may require decades due to nutrient legacies and long ecosystem memory. 

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