Wetland Biomass Research Articles

Characteristics of Dissolved Organic Matter as Affected by Decomposition of Different Organic Materials in Alpine Wetland

Dissolved organic matter (DOM) plays a significant role in the nutrient supply, energy flow, and pollutant transportation in the wetland ecosystem. However, little is known about the effect of the decomposition of different organic materials in alpine wetland water on the DOM characteristics. By conducting a 90-day decomposition experiment with the addition of different organic materials (peat soil, yak manure, and plant litter) alone or their combinations into alpine wetland water, we characterized the water DOM using three-dimension excitation-emission matrix spectroscopy. The results showed that the decomposition of organic materials significantly affected the chemical properties, sources, humification degree, and composition of the water DOM. The decomposition increased dissolved organic carbon and dissolved total nitrogen in the water. For most of the water samples, a fluorescence index ranging from 1.4 to 1.7 and a biological index of less than 0.8 may indicate that both autochthonous and allochthonous sources contributed to the water DOM, which may primarily rely on allochthonous sources. UVA (37.55–46.81% of total fluorescent components) and UVC fulvic-like substances (29.91–35.53% of total fluorescent components) dominated the water DOM compositions. Among the treatments, additions of peat soil and yak manure led to the highest and the lowest humification degree of the water DOM, respectively. For the treatment of the combination decomposition of all three organic materials, the yak manure may stimulate microbial activity and facilitate the decomposition of plant litter and peat soil and, therefore, boost the humic-like substances in the water DOM. These findings may help the development of wetland biomass management with the objective of maintaining alpine wetland ecosystem services.

Efficient reclamation of phosphorus from wetland biomass waste via liquid-recirculated hydrothermal carbonization and precipitation

Hydrothermal carbonization (HTC) for the recovery of phosphorus (P) from biomass wastes has attracted considerable attention, while migration of P to the liquid phase greatly weakened P recovery efficiency and elevated the environmental risk. Therefore, a systematic scheme was proposed in this work to accomplish the complete reclamation of P from wetland plant (Ceratophyllum demersum) through coupling liquid-recirculated HTC mediated by H2O or H2SO4 with precipitation, and the migration and speciation of P during this process was determined by P K-edge X-ray absorption near edge structure, 31P nuclear magnetic resonance, and the modified sequential extraction. The P concentration in the liquid phase increased with the recirculation of HTC process water, and reached up to 550.6 mg L-1. >98.1 % of P in the recirculated liquid products was recovered in the forms of hydroxyapatite and struvite with the HTC mediums of H2O and H2SO4, respectively, without the addition of exogenous metals. In addition to the production of P compounds, P-enriched hydrochar was simultaneously obtained during this process. The HTC medium and liquid recirculation had profound impact on the hydrochar characteristics and the transformation of P. Hydroxyapatite and magnesium phosphate were the dominant P species in the hydrochars derived from H2O-mediated HTC, while FePO4 and other Ca-P species [Ca3(PO4)2 and Ca(H2PO4)2] dominated the P compounds in the H2SO4-mediated hydrochar. These results suggest that coupling liquid-recirculated HTC and precipitation could be a promising strategy for P reclamation, which could provide new insights into the P recovery from biomass waste.

Influence of Four Veterinary Antibiotics on Constructed Treatment Wetland Nitrogen Transformation.

The use of wetlands as a treatment approach for nitrogen in runoff is a common practice in agroecosystems. However, nitrate is not the sole constituent present in agricultural runoff and other biologically active contaminants have the potential to affect nitrate removal efficiency. In this study, the impacts of the combined effects of four common veterinary antibiotics (chlortetracycline, sulfamethazine, lincomycin, monensin) on nitrate-N treatment efficiency in saturated sediments and wetlands were evaluated in a coupled microcosm/mesocosm scale experiment. Veterinary antibiotics were hypothesized to significantly impact nitrogen speciation (e.g., nitrate and ammonium) and nitrogen uptake and transformation processes (e.g., plant uptake and denitrification) within the wetland ecosystems. To test this hypothesis, the coupled study had three objectives: 1. assess veterinary antibiotic impact on nitrogen cycle processes in wetland sediments using microcosm incubations, 2. measure nitrate-N reduction in water of floating treatment wetland systems over time following the introduction of veterinary antibiotic residues, and 3. identify the fate of veterinary antibiotics in floating treatment wetlands using mesocosms. Microcosms containing added mixtures of the veterinary antibiotics had little to no effect at lower concentrations but stimulated denitrification potential rates at higher concentrations. Based on observed changes in the nitrogen loss in the microcosm experiments, floating treatment wetland mesocosms were enriched with 1000 μg L-1 of the antibiotic mixture. Rates of nitrate-N loss observed in mesocosms with the veterinary antibiotic enrichment were consistent with the microcosm experiments in that denitrification was not inhibited, even at the high dosage. In the mesocosm experiments, average nitrate-N removal rates were not found to be impacted by the veterinary antibiotics. Further, veterinary antibiotics were primarily found in the roots of the floating treatment wetland biomass, accumulating approximately 190 mg m-2 of the antibiotic mixture. These findings provide new insight into the impact that veterinary antibiotic mixtures may have on nutrient management strategies for large-scale agricultural operations and the potential for veterinary antibiotic removal in these wetlands.

Insights into the behavior and kinetics of purun tikus degradation during slow pyrolysis

Purun tikus (Elocharis dulcis), a type of wetland biomass feedstock, is a challenge to the swamp ecosystem as it contributes to pollution in the area. Hence, integrating the use of purun tikus as a source of bioenergy, particularly in the form of bio-oil, is of the highest priority. Nevertheless, there is a lack of research on the degradation rate of purun tikus conversion to bio-oil through pyrolysis. Thus, this study aims to evaluate the rate of destruction of purun tikus in the process of conversion into bio-oil via pyrolysis. In the experiment, a batch reaction vessel was used to carry out slow pyrolysis at temperatures ranging from 300 to 500 °C, and the reaction times ranged from 60 to 120 min. By assuming a first-order process and using the Arrhenius equation, it was possible to figure out the activation energy and the preexponential factort. To determine whether purun tikus destroyed during pyrolysis, an activation energy of 43.317 kJ mol-1 and a pre-exponential factor of 0.351 s-1 were identified.

Giant reed from wetlands as a potential resource for biomethane production

This study aimed to evaluate the potential and the use of the natural and treatment wetland biomass for local energy production. Specifically, it was addressed by determining the giant reed (Arundo donax L.) Biochemical Methane Potential at different harvest times, since plant characteristics vary noticeably along the growing season. In the last decades, this perennial rhizomatous grass has achieved great success in the renewable energy market to produce biogas through the anaerobic digestion process, because is a non-food crop with high biomass yield (about 35 Mg dry matter per hectare) and low input required for its growth. Several studies showed that the harvest time, in relation to the stage of the plant development, significantly affect the Biochemical Methane Potential. Moreover, it is well known that giant reed presents feature comparable in terms of biomass yield and physicochemical composition both in natural and treatment wetland systems. Anaerobic digestion laboratory tests were carried out to assess biomethane production from aerial biomass samples collected from July to November 2021. The average biogas production for the five different harvest times was of 312.77 Nm3/tVS (±62.87), and the mean methane content was equal to 187.06 Nm3 CH4/tVS (±38.32). The gas quality at the end of the Biochemical Methane Potential test displayed average contents of methane of 58.88% (±5.06) and CO2 of 18.54% (±7.91) and mean sulfides content of 112.10 ppm (±103.61). The results highlighted that giant reed has a high energy returned on energy invested (EROEI) value. The research activity allowed to identify the harvest time associated with the highest Biochemical Methane Potential and biomethane production per hectare. Finally, the experimental results achieved in riverbank conditions could be applied to treatment wetland systems increasing their environmental sustainability and reducing their maintenance costs.

Environmental Factors, Biomass, and Function of Wetlands

Wetlands are an important part of the biosphere. Wetlands not only impact the natural environment but also play vital roles in human life. This paper starts with the classification, distribution, and main functions of wetlands, then analyzes the relationship between wetlands and the biosphere from several aspects, including the factors that affect wetlands, the biomass of wetlands, the importance of wetlands for carbon storage, and the threats that wetlands may face. Based on previous research, wetlands can be impacted by environmental factors, such as water supply and temperature, and biological factors, including aboveground biomass and below-ground biomass. When interacting with these factors, wetlands can play crucial roles in the biosphere, such as facilitating the circulation of energy and materials and the storage of carbon. However, wetlands are facing threats. After analyzing the current state of wetlands, possible solutions are considered. Both research and society can make efforts to improve wetlands ecosystems. This report is significant for understanding the current situation and the direction of future development of wetlands. It is crucial to study the environmental factors affecting wetlands, considering the protection, improvement, and future development of wetland ecosystems depend on their surroundings to a great extent. Interactions between wetlands and the environment directly or indirectly determine the state of wetlands.

Growth of water hyacinth biomass and its impact on the floristic composition of aquatic plants in a wetland ecosystem of the Brahmaputra floodplain of Assam, India.

Inland water plants, particularly those that thrive in shallow environments, are vital to the health of aquatic ecosystems. Water hyacinth is a typical example of inland species, an invasive aquatic plant that can drastically alter the natural plant community's floral diversity. The present study aims to assess the impact of water hyacinth biomass on the floristic characteristics of aquatic plants in the Merbil wetland of the Brahmaputra floodplain, NE, India. Using a systematic sampling technique, data were collected from the field at regular intervals for one year (2021) to estimate monthly water hyacinth biomass. The total estimate of the wetland's biomass was made using the Kriging interpolation technique. The Shannon-Wiener diversity index (H'), Simpson's diversity index (D), dominance and evenness or equitability index (E), density, and frequency were used to estimate the floristic characteristics of aquatic plants in the wetland. The result shows that the highest biomass was recorded in September (408.1 tons/ha), while the lowest was recorded in March (38 tons/ha). The floristic composition of aquatic plants was significantly influenced by water hyacinth biomass. A total of forty-one plant species from 23 different families were found in this tiny freshwater marsh during the floristic survey. Out of the total, 25 species were emergent, 11 were floating leaves, and the remaining five were free-floating habitats. Eichhornia crassipes was the wetland's most dominant plant. A negative correlation was observed between water hyacinth biomass and the Shannon (H) index, Simpson diversity index, and evenness. We observed that water hyacinths had changed the plant community structure of freshwater habitats in the study area. Water hyacinth's rapid expansion blocked out sunlight, reducing the ecosystem's productivity and ultimately leading to species loss. The study will help devise plans for the sustainable management of natural resources and provide helpful guidance for maintaining the short- to the medium-term ecological balance in similar wetlands.

Effects of Land Use Changes on the Plant Community Characteristics in the Wetlands of the Semi-Arid Regions

Human disturbance is the main driving factor of wetland vegetation degradation, and plant community changes can directly characterize the process of wetland degradation. The wetlands in semi-arid region of Songnen Plain perform the important ecological functions, especially the habitat of waterbirds. Recently, the succession of wetland plant community has been accelerated by land use changes. In this study, we investigated the variations of plant community in wetlands undergoing land use changes (natural, mowing, light grazing + mowing, moderate grazing and heavy grazing wetlands) in the western Songnen Plain. The results showed that the plant communities were significantly affected by land use changes. The typical wetland plant Calamagrostis angustifolia was the dominant species in natural wetlands, and its dominance was gradually decreased in mowing or grazing wetlands in where Carex spp. or Artemisia selengensis acting as the dominant species. The height, density, and biomass in natural wetlands were significantly higher than those in other wetlands, whereas the species diversity and richness in natural wetlands were significantly lower. The similarity index of plant community in wetlands undergoing land use changes to natural wetlands ranged from 17.7–45.1%, being the highest in mowed wetlands and the lowest in heavily grazed wetlands. The linear regression further indicated that the plant diversity index was negatively correlated with the aboveground biomass of grasses and positively correlated with the aboveground biomass of forbs. Therefore, the land use changes in wetlands drove the replacement of dominant species of wetland vegetation and changed plant community characteristics and the species diversity, and the maintenance of species diversity is linked with the variability in plant functional strategies. The results of community variations and their relationships with functional changes can be used for assessing the effects of degradation and ecological function in response of land use changes in wetlands.

Long-term nitrogen enrichment accelerates soil respiration by boosting microbial biomass in coastal wetlands

Coastal wetlands are essential in terrestrial carbon balance because they act as natural “blue carbon” sinks, influenced by anthropogenic nitrogen (N) enrichment. N enrichment alters soil environment and plant growth, impacting carbon loss through soil respiration (Rsoil). However, the responses of Rsoil to N enrichment remain elusive in coastal wetlands, hindering the estimation of carbon fluxes. To bridge this knowledge gap, we used an 8-year field N fertilization platform in the coastal wetlands of the Yellow River Delta, China, to measure Rsoil composed of heterotrophic respiration and autotrophic respiration, and multiple indicators of soil properties, microbial activities, and plant growth. We found long-term N enrichment increased Rsoil by 26.6 ± 1.2% (mean ± standard deviation) and quadrupled microbial biomass carbon, accounting for 26.9 ± 1.2% of the increase in heterotrophic respiration. In addition, N enrichment boosted plant growth, increasing the above-ground biomass by 28.7 ± 6.9% while inducing a cooling effect that partly offsets the increase in autotrophic respiration. In particular, N enrichment elevated soil temperature sensitivity of Rsoil with the increase of N levels, suggesting that the nutrient-related control of Rsoil responds to warming. The study indicates that N enrichment stimulates Rsoil in coastal wetlands by boosting microbial biomass carbon through interactions between soil environmental conditions and plant growth. These results have implications for predicting the carbon cycle with anthropogenic N enrichment.

Sea-level rise predicted to reduce exotic mangrove distribution and biomass in coastal wetlands in southern China

The adverse effects of sea-level rise on coastal wetlands have been extensively reported, whereas the positive effects on wetland composition have tended to receive less attention. Using a coupled hydro-vegetation model, we modeled the spatial and temporal distribution of native and exotic mangroves for 120 years in a mangrove forest in southern China in scenarios with and without sea-level rise. After approximately 50 years, the self-reinforcing feedback between mangroves and subsurface salinity is expected to create a stable ecosystem. Without sea-level rise, salt-sensitive exotic species will inhibit the growth of native mangroves, potentially leading to a more fragile ecosystem. Native mangroves are predicted to grow best under moderate sea-level rise (0.5 m). If sea level rises by 1 m, exotic mangrove populations in southern China are predicted to drastically decline. Competition between salt-tolerant and salt-intolerant plants is common in coastal wetlands, and the modeling method presented in this study may be globally applicable.

Estimation of aboveground biomass and carbon in palustrine wetland using bands and multispectral indices derived from optical satellite imageries PlanetScope and Sentinel-2A

Facing the climate change and anthropogenic activities that have been discharging a large proportion of carbon dioxide CO2) into the atmosphere, wetlands stand out as an important sink for CO2 that is fixed in plant biomass and peatlands. Therefore, quantifying and monitoring wetland biomass is of great importance to preserve carbon stocks. This study aims to explore the potential of multispectral bands and vegetation indices (VIs) derived from PlanetScope and Sentinel-2A sensors to estimate of aboveground biomass (AGB) and organic carbon in AGB (Corg) in the emergent vegetation of a palustrine wetland. We use correlation analysis and linear regression models to examine the relationships between spectral and biophysical variables and verify the best predictor spectral variables for AGB and Corg. Scirpus giganteus vegetation was sampled in the Banhado Grande wetland, in southern Brazil. The VIs were best correlated and preferred as predictor variables. The most accurate model used data from the PlanetScope sensor and VI of photochemical reflectance. Both sensors showed potential for pixel-based estimates of AGB and Corg due to their low RMSE values and their contribution as predictors of biophysical variables, which can contribute to opening new avenues in scientific research focusing on the management, monitoring, and conservation of marshes and your ecosystem service of carbon sink.

Coupling Anaerobic Digestion with Pyrolysis for Phosphorus-Enriched Biochar Production from Constructed Wetland Biomass

Coupling Anaerobic Digestion with Pyrolysis for Phosphorus-Enriched Biochar Production from Constructed Wetland Biomass

Co-Pyrolysis of Sewage Sludge and Wetland Biomass Waste for Biochar Production: Behaviors of Phosphorus and Heavy Metals.

Large amounts of sewage sludge (SS) and wetland plant wastes are generated in the wastewater treatment system worldwide. The conversion of these solid wastes into biochar through co-pyrolysis could be a promising resource utilization scheme. In this study, biochar was prepared by co-pyrolysis of SS and reed (Phragmites australis, RD) using a modified muffle furnace device under different temperatures (300, 500, and 700 °C) and with different mixing ratios (25, 50, and 75 wt.% RD). The physicochemical properties of biochar and the transformation behaviors of phosphorus (P) and heavy metals during the co-pyrolysis process were studied. Compared with single SS pyrolysis, the biochar derived from SS-RD co-pyrolysis had lower yield and ash content, higher pH, C content, and aromatic structure. The addition of RD could reduce the total P content of biochar and promote the transformation from non-apatite inorganic phosphorus (NAIP) to apatite phosphorus (AP). In addition, co-pyrolysis also reduced the content and toxicity of heavy metals in biochar. Therefore, co-pyrolysis could be a promising strategy to achieve the simultaneous treatment of SS and RD, as well as the production of value-added biochar.

Specific Methane Yield of Wetland Biomass in Dry and Wet Fermentation Technologies

Our study evaluated the specific methane yield (SMY) of selected wetland species subjected to wet and dry anaerobic digestion: Carex elata All. (CE), a mixture (~50/50) of Carex elata All. and Carex acutiformis L. (CA), Phragmites australis (Cav.) Trin. ex Steud. (PA), Typha latifolia L. (TL) and Phalaris arundinacea L. (PAr). Plants were harvested in late September, and therefore, the study material was characterised by high lignin content. The highest lignin content (36.40 ± 1.04% TS) was observed in TL, while the lowest (16.03 ± 1.54% TS) was found in CA. PAr was characterised by the highest hemicellulose content (37.55 ± 1.04% TS), while the lowest (19.22 ± 1.22% TS) was observed in TL. Cellulose content was comparable in almost all plant species studied and ranged from 25.32 ± 1.48% TS to 29.37 ± 0.87% TS, except in PAr (16.90 ± 1.29% TS). The methane production potential differed significantly among species and anaerobic digestion (AD) technologies. The lowest SMY was observed for CE (121 ± 28 NL kgVS−1) with dry fermentation (D–F) technology, while the SMY of CA was the highest for both technologies, 275 ± 3 NL kgVS−1 with wet fermentation (W–F) technology and 228 ± 1 NL kgVS−1 with D–F technology. The results revealed that paludi-biomass could be used as a substrate in both AD technologies; however, biogas production was more effective for W–F. Nonetheless, the higher methane content in the biogas and the lower energy consumption of technological processes for D–F suggest that the final amount of energy remains similar for both technologies. The yield is critical in energy production by the AD of wetland plants; therefore, a promising source of feedstock for biogas production could be biomass from rewetted and previously drained areas, which are usually more productive than natural habitats.

Potential Use of Plant Biomass from Treatment Wetland Systems for Producing Biofuels through a Biocrude Green-Biorefining Platform

The potential of using the biomass of four wetland plant species (Iris pseudacorus, Juncus effusus, Phragmites australis and Typha latifolia) grown in treatment wetland systems and under natural conditions were tested to produce high-value materials using hydro-thermal liquefaction (HTL). The results show that the wetland plants biomass is suitable for biocrude and biochar production regardless of the origin. The hydrothermal liquefaction products’ (biocrude, biochar, aqueous and gaseous phase) yields vary according with the specific biomass composition of the species. Furthermore, the results show that the biomass composition can be affected by the growing condition (treatment wetland or natural unpolluted conditions) of the plants. None of the single components seems to have a determinant effect on the biocrude yields, which reached around 30% for all the analyzed plants. On the contrary, the biochar yields seem to be affected by the composition of the biomass, obtaining different yields for the different plant species, with biochar yields values from around 12% to 22%, being that Phragmites australis is the one with the highest average yield. The obtained aqueous phase from the different plant species produces homogeneous compounds for each plant species and each growing environment. The study shows that biomass from treatment wetlands is suitable for biocrude production. The environmental value of this biomass lies on the fact that it is considered a residual product with no aggregated value. The treatment wetland biomass is a potential sustainable source for biofuel production since these plants do not need extra land or nutrients for growing, and the biomass does not compete with other uses, offering new sources for enhancing the bioeconomy concepts.

Getting to the root of the problem: improving measurements of mangrove belowground production and carbon sequestration.

This article is a Commentary on Arnaud et al. (2021), 232: 1591–1602.

Buried hurricane legacies: increased nutrient limitation and decreased root biomass in coastal wetlands

AbstractPlant identity and cover in coastal wetlands is changing in worldwide, and many subtropical salt marshes dominated by low‐stature herbaceous species are becoming woody mangroves. Yet, how changes affect coastal soil biogeochemical processes and belowground biomass before and after storms is uncertain. We experimentally manipulated the percent mangrove cover (Avicennia germinans) in 3 × 3 m cells embedded in 10 plots (24 × 42 m) comprising a gradient of marsh (e.g., Spartina alterniflora, Batis maritima) and mangrove cover in Texas, USA. Hurricane Harvey made direct landfall over our site on 25 August 2017, providing a unique opportunity to test how plant composition mitigates hurricane effects on surface sediment accretion, soil chemistry (carbon, C; nitrogen, N; phosphorus, P; and sulfur, S), and root biomass. Data were collected before (2013 and 2016), one‐month after (2017), and one‐year after (2018) Hurricane Harvey crossed the area, allowing us to measure stocks before and after the hurricane. The accretion depth was higher in fringe compared with interior cells of plots, more variable in cells dominated by marsh than mangrove, and declined with increasing plot‐scale mangrove cover. The concentrations of P and δ34S in storm‐driven accreted surface sediments, and the concentrations of N, P, S, and δ34S in underlying soils (0–30 cm), decreased post‐hurricane, whereas the C concentrations in both compartments were unchanged. Root biomass in both marsh and mangrove cells was reduced by 80% in 2017 compared with previous dates and remained reduced in 2018. Post‐hurricane loss of root biomass in plots correlated with enhanced nutrient limitation. Total sulfide accumulation as indicated by δ34S, increased nutrient limitation, and decreased root biomass of both marshes and mangroves after hurricanes may affect ecosystem function and increase vulnerability in coastal wetlands to subsequent disturbances. Understanding how changes in plant composition in coastal ecosystems affects responses to hurricane disturbances is needed to assess coastal vulnerability.

Mangrove growth response to experimental warming is greatest near the range limit in northeast Florida.

Shrubs are invading into grasslands around the world, but we don't yet know how these shrubs will fare in a warmer future. In ecotonal coastal wetland ecosystems, woody mangroves are encroaching into herbaceous salt marshes owing to changes in temperature, precipitation, and sediment dynamics. Increasing mangrove biomass in wetlands often increases carbon storage, which is high in these productive ecosystems, but little is known about how mangrove growth will change in response to warming. To address this knowledge gap, we deployed warming experiments at three coastal wetland sites along a latitudinal gradient in northeast Florida where Avicennia germinans, black mangroves, are encroaching into salt marshes. We achieved air temperature warming (+1.6°C during the day) at all three sites and measured stem elongation, canopy height and area changes, and leaf and node number. After 2 yr of warming, we found that mangrove growth rate in height increased due to warming. Warming increased stem elongation by 130% over unwarmed control plots after 1 yr at the northern site. Mangrove growth in canopy area did not respond to warming. Site differences in growth rate were pronounced, and mangrove growth in both height and area were lowest at the northern site, despite greater impacts of warming at that site. We also found that area-based relative growth rate was five times higher across all treatments than height-based relative growth rate, indicating that mangroves are growing wider rather than taller in these ecotonal environments. Our findings indicate that the growth effect of experimental warming depends on site characteristics and growth parameter measured. We also propose that differential mangrove growth across the three sites may be driven by biotic factors such as the identity of the salt marsh species into which mangroves are encroaching. Our results suggest that, as seen in other ecosystems, wetland plants may respond most strongly to warming at their poleward range edge.

Larval anurans follow predictions of stoichiometric theory: implications for nutrient storage in wetlands

AbstractEcological stoichiometry provides a framework to predict how animals regulate nutritional balances within their tissue and, as a result, how animal biomass affects ecosystem processes through nutrient cycling. However, most interspecific and developmental stoichiometric studies in animals focus on invertebrates, and the few vertebrate studies are largely fish‐centric. Larval anurans are ideal vertebrates to test predictions of developmental and interspecific stoichiometry as they undergo a complex development, exhibit broad arrays of life‐history traits, and can constitute high animal biomass in wetlands, implying major roles in wetland nutrient storage and cycling. We examined (1) patterns of body stoichiometry across larval developmental stages within multiple anuran species, (2) whether key predictors of stoichiometric change, specifically body size, developmental period, and breeding season, influence interspecific stoichiometric variation, and (3) natural magnitudes and fluctuations of larval anuran nutrient storage in geographically isolated wetlands (GIWs). We measured carbon (C), nitrogen (N), and phosphorus (P) tissue content in larval anurans across five developmental stages within 11 species collected from four GIWs to examine patterns of developmental and interspecific stoichiometry. Within species, we found broad developmental stoichiometric patterns in which later developmental stages were lower in %N, but higher in %P than earlier stages. Patterns in %C were inconsistent but were generally lower in later stages, while tissue C:N ratios increased, and C:P and N:P decreased in later developmental stages. Interspecific stoichiometric variation was partially explained by body size and developmental period which positively affected %C and C:N ratios. We observed spatial and temporal fluctuations in species‐specific biomass which dictated nutrient storage patterns within larval anuran assemblages, though stoichiometric identity played a major role. Our estimated magnitudes of larval anuran areal nutrient storage also greatly exceeded that of other wetland fauna with the maximum estimated areal P storage reaching over 200 times that of a similar‐density co‐occurring invertebrate group. These results highlight stoichiometric patterns of development and interspecific variation in a diverse group of amphibians while providing critical baseline information for elucidating the role of anurans in wetland nutrient dynamics.

Characterizing spatial variability in coastal wetland biomass across multiple scales using UAV and satellite imagery

AbstractCoastal wetland biomass is an important indicator of wetland productivity, carbon storage, health, and vulnerability to climate change. The ability to estimate aboveground biomass (AGB) in wetlands at ecologically relevant scales is complicated by the spatial variability inherent to patterns in wetland vegetation and the biogeomorphic processes that help create them. Remote sensing provides an approach for mapping wetland biomass, but the spatial resolutions of satellite and airborne imagery often constrain the types of ecological patterns and processes that can be detected. Unmanned Aerial Vehicles (UAVs) have previously been used to capture fine‐scale (≤1 m) variability in AGB in coastal wetland settings. However, it remains unclear if a UAV approach to estimating wetland biomass is transferrable across diverse wetland sites or how it compares to commonly used satellite‐based approaches. Here, we test the capabilities of UAVs in remotely quantifying AGB and compare biomass estimation using UAV and Landsat satellite imagery (30 m resolution) in several wetland sites in Southern California. Field surveys highlight significant spatial variability in wetland plant community AGB and height that influence remote biomass estimation. Relationships between UAV vegetation indices and AGB were site‐specific and influenced by vegetation types. Biomass estimation using UAVs (r2 = 0.40, RMSE = 534.6 g m−2) showed better correlation with NDVI than a Landsat‐based approach (r2 = 0.26, RMSE = 596.8 g m−2). We found combining high‐resolution UAV AGB maps and Landsat NDVI to develop AGB models showed the highest correlation (r2 = 0.45, RMSE = 659.7 g m−2) and provided additional spatial information to aid scaling field data to satellite imagery. Overall, UAVs captured more spatial complexity in aboveground biomass at finer scales than is possible with moderate‐resolution Landsat pixels, indicating that UAVs can be used to characterize patterns of within‐marsh variability resulting from local‐scale (≤ 100s of meters) ecological processes.