Bethel ME, a small village nestled in the heart of the Maine Pegmatite Belt, holds a secret that everyone who cares about minerals should know about: the Maine Mineral & Gem Museum (MMGM). Situated ...on the eastern flank of the White Mountains, just 10 miles east of the New Hampshire border and 30 miles from Mount Washington, Bethel is an easy hour and a half drive from Portland, itself a vacation destination filled with great restaurants, brew pubs, lobster joints, and seaside ambiance. The drive from Portland winds through scenic Maine woods with roadside signs beckoning one to try their hand at fee digging at one of several active pegmatite mines. Summer camping is abundant and the fall foliage is legendary. In short, it's a great getaway place year-round with full creature comforts within easy walking distance... including minerals, gems, meteorites, and more!
Identification of spores, acritarchs, and chitinozoans in weakly metamorphosed (≥ 300 °C) turbidites demonstrates the usefulness of palynological dating for hitherto unfossiliferous strata that ...underlie much of the Gander terrane in Maine. Combined with sparse macrofossil ages and geochronologic data from detrital zircons, volcanic horizons, and plutons, the fossils constrain the ages of strata in the Central Maine/Aroostook-Matapedia (CMAM) basin and Fredericton trough and help to resolve paleogeographic and tectonic problems. Ages for the provisional Brewer (Upper Ordovician to Llandovery) and Bangor (Wenlock) formations in the Bangor area fill the last remaining gap in CMAM basin stratigraphy and permit correlation across the entire basin, from western Maine to the New Brunswick border. Resulting lithofacies patterns document basinward facies changes from both eastern and western external sources, and also indicate internal sources within the basin. A progressive decrease in carbonate sediment in the CMAM basin toward the south suggests interaction between axial and basinward currents in which micrite transported by axial currents from the Matapedia platform in northern New Brunswick was progressively overwhelmed to the south by clastic sedimentation from flanking highland sources. Middle to late Silurian age ranges for the Flume Ridge Formation, the most extensive unit in the Fredericton trough, and the newly named County Road Formation permit correlation with rocks in similar structural positions in New Brunswick. Recent geologic mapping, the new age control, and improved understanding of facies relationships show that the CMAM basin was perhaps as wide as 800 to 1000 km prior to deformation; developed on continental crust after mid-Ordovician plate accretion; contained a body of deep water with anoxic bottom conditions and mostly pelagic organisms; and contains a series of overlapping submarine fans derived from multiple sources.
Core Ideas
Chronic N enrichment increased N exports, although ecosystem N retention was still high.
Soil was the largest ecosystem N pool, but it was not significantly altered by chronic N ...enrichment.
Chronic N enrichment increased biomass N accumulation in hardwood but not in softwood stands.
We examine the temporal trend of input–output N fluxes and net ecosystem N retention, and estimate a mass balance for ecosystem soil and vegetation pools, after 25 yr of chemical manipulation at the Bear Brook Watershed in Maine (BBWM). The BBWM is a paired whole watershed manipulation experiment designed to study the effects of elevated N and S deposition on forest ecosystem function. Starting in 1989, 25.2 kg N ha−1 was added annually to the West Bear (treated) watershed. The N additions in West Bear stimulated N loss through stream exports, and West Bear retained 81% of the annual N inputs, compared to 94% retention in the reference, East Bear. After 25 yr of N additions, the West Bear watershed had accumulated ∼700 kg ha−1 more N than East Bear in soils and vegetation, with ∼10% of the accumulated N stored in forest biomass. The treatment increased recent biomass N accumulation rates in the hardwood stands, but not in the softwoods. Soils did not show detectable differences in total N content between watersheds, although the organic soils had greater N in West Bear. This paper presents a unique set of findings from one of the few long‐term whole forest ecosystem N enrichment studies in the world. While N dynamics were clearly altered in West Bear, with evidence of accelerated N cycling, the treated watershed did not attain an advanced stage of N saturation during the study period, based on the evidence from forest growth and stream N exports.
This study examines the impact of variation in root‐zone soil moisture (RZSM), a key component of the Earth's hydrologic cycle and climate system, on regional carbon fluxes across seven North ...American ecosystems. P‐band synthetic aperture radar‐derived RZSM estimates were incorporated into the ecosystem demography (ED2) terrestrial biosphere model through a model‐data blending approach. Analysis shows that the model qualitatively captures inter‐daily and seasonal variability of observed RZSM at seven flux tower sites (r = 0.59 ± 0.26 and r = 0.70 ± 0.22 for 0–10 and 10–40 cm of soil layers, respectively; P < 0.001). Incorporating the remotely sensed RSZM estimates increases the accuracy (root‐mean‐square deviations decrease from 0.10 ± 0.07 and 0.09 ± 0.06 m3·m−3 to 0.08 ± 0.05 and 0.07 ± 0.03 m3 ·m−3 for 0–10 and 10–40 cm of soil layers, respectively) of the model's RZSM predictions. The regional carbon fluxes predicted by the native and RZSM‐constrained model were used to quantify sensitivities of gross primary productivity, autotrophic respiration (Ra), heterotrophic respiration (Rh), and net ecosystem exchange to variation in RZSM. Gross primary productivity exhibited the largest sensitivity (6.6 ± 10.7 kg·cm−2·year·θ−1) followed by Ra (2.9 ± 7.3 kg·cm−2·year−1·θ−1), Rh (2.6 ± 3.1 kg·cm−2·year−1·θ−1), and net ecosystem exchange (−1.7 ± 7.8 kg·cm−2·year−1·θ−1). Analysis shows that these carbon flux sensitivities varied considerably across regions, reflecting influences of canopy structure, soil properties, and the ecophysiological properties of different plant functional types. This study highlights (1) the importance of improved terrestrial biosphere model predictions of RZSM to improve predictions of terrestrial carbon fluxes, (2) a need for improved pedotransfer functions, and (3) improved understanding of how soil characteristics, climate, and vegetation composition interact to govern the responses of different ecosystems to changing hydrological conditions.
Key Points
The sensitivity of ecosystem carbon fluxes to root‐zone soil moisture varies markedly across regions and vegetation types in North America
Ecosystems with highest carbon flux moisture sensitivities are eastern deciduous forests, western conifer forests, and dryland grasslands
Findings highlight the importance of improving terrestrial biosphere model predictions of regional soil moisture dynamics
Seeley et al., 2024 (Comment: A reexamination of Johnston et al., 2023, bed-scale impact and recovery of a commercially important intertidal seaweed. J. Exp. Mar. Biol. Ecol. 574) describe a number ...of reasons that they believe our study's experimental design was flawed and our inferential conclusions were incorrect. We believe that these claims are the result of misunderstandings of the objectives behind our sampling design and statistical analyses. Throughout this response to Seeley et al., we reiterate key objectives of our study design: examining rockweed harvest at a whole-bed scale, realistically capturing the effects of current commercial rockweed harvest methods in Maine, and using coastwide site averages to estimate effect sizes of rockweed harvest. The first claim by Seeley et al. that our study design severely undersampled rockweed beds ignores established sampling methodologies in rockweed research. The suggestion that our sampling design resulted in impact sites that were de facto control sites is not supported by our analyses that showed greater declines in mean rockweed height and biomass at impact sites relative to control sites. In response to their second claim that rockweed companies had control of key elements of our study design and execution, we detail our specific approaches to lessen any possibility for such conflicts to bias our findings. In the final section of our response, we present power analyses in support of our Before-After Control-Impact study design and we highlight the statistically significant effects of treatment on rockweed biomass that contradict Seeley et al.'s claim that we drew conclusions about biomass recovery based solely on large p-values.
Incidence of human granulocytic anaplasmosis is rising in Maine, USA. This increase may be explained in part by adoption of tick panels as a frequent diagnostic test in persons with febrile illness ...and in part by range expansion of Ixodes scapularis ticks and zoonotic amplification of Anaplasma phagocytophilum.
We measured total carbon stocks of three marshes: Two formed in association with a developing spit along the Gulf of St. Lawrence coast of New Brunswick, Canada, and another with a lagoon on the ...coast of Maine, USA. Overall, 46 cores and 157 depth recordings were collected to determine depth of the marsh deposits. Total marsh soil volume was estimated by interpolation. In all marshes soil depth varied in a predictable pattern based upon marsh developmental history. In spit marshes deposit age and thickness increased towards the oldest portion of the spit. In the lagoonal marsh, soil depth was greatest in the center and declined towards both the upland and seaward margins. This same pattern held on axes perpendicular to the primary, age axis of the spit marshes. In each marsh C density did not significantly vary with depth so that marsh depth was an acceptable estimator of C stock, and therefore driven by the geomorphic context of the marshes we studied. There were major differences in C stock estimates produced using GIS interpolation, average C contained in all marsh cores, or cores along a single transect. Our study demonstrates that assuming a soil depth of just 0.5 or 1 m can substantially under- or overestimate marsh carbon stocks and the value of that stock on a carbon market.
•Soil C storage is estimated for two spit and one lagoonal salt marsh.•Soil depth varied in a pattern predictable by environmental history.•Significant variation in carbon storage found between estimation techniques.•Consistent C density enables C stock estimates using soil volume within marshes.•Using standard soil depths can substantially over or under- estimate C stocks.
Microplastics (MP) are found in marine sediments across the globe, but we are just beginning to understand their spatial distribution and assemblages. In this study, we quantified MP in Gulf of ...Maine, USA sediments. MP were extracted from 20 sediment samples, followed by polymer identification using Raman spectroscopy. We detected 27 polymer types and 1929 MP kg−1 wet sediment, on average. Statistical analyses showed that habitat, hydrodynamics, and station proximity were more important drivers of MP assemblages than land use or sediment characteristics. Stations closer to one another were more similar in their MP assemblages, tidal rivers had higher numbers of unique plastic polymers than open water or embayment stations, and stations closer to shore had higher numbers of MP. There was little evidence of relationships between MP assemblages and land use, sediment texture, total organic carbon, or contaminants.
Display omitted
•Sediments from the Gulf of Maine were extracted and analyzed for microplastics.•Concomitant site data for each station were analyzed versus MP assemblage.•Habitat, hydrodynamics, and station proximity were important drivers of MP assemblage.•Land use and sediment characteristics had little effect on MP assemblage.•Methods must be less time and labor intensive for feasible largescale monitoring.
We applied a diatom-based thermal stratification index to sediment cores from three lakes in the northeast USA to evaluate the influence of lake morphometry and within-lake processes on diatom ...responses to climate change. The three lakes all had surface area >5 km
2
and experienced the same regional declines in wind speed and progressively earlier ice-out dates, but differed in morphometry, particularly surface area and mean depth. We coupled this paleolimnological approach with contemporary ecological measurements to validate the use of two indicator species (
Aulacoseira subarctica
(O. Müller) Haworth and
Discostella stelligera
(Cleve & Grunow) Houk & Klee) in the stratification index.
D. stelligera
was abundant during stratified conditions in Tunk Lake and Sebago Lake, but not in Lobster Lake. Diatom-inferred stratification shifted to shallower and/or longer duration in Tunk Lake starting in the late nineteenth century, and continued to become shallower over much of the twentieth century. A shift to shallower and/or longer duration was also apparent in Sebago Lake starting around 1850, after which the index suggested little change, even though ice-out occurred 30 days earlier in 2000 than in 1807 and wind speed began to decline in the 1960s. This lake has very slow sedimentation rates, experiences regular seiches, and has
D. stelligera
present during circulation and stratified periods. These factors may smooth stratification-driven diatom responses. Contemporary ecological measurements did not support the application of the stratification index in Lobster Lake because
D. stelligera
bloomed only during spring turnover. In Lobster Lake, the relative abundances of
D. stelligera
in the sediment record showed some variation over time, were generally lower in periods with earlier ice-out in the region, and have been lower since the 1980s. Our results highlight the different responses recorded in the sediments of three large lakes in the same region to climate-driven changes and support the use of indicator species in reconstructing lake thermal stratification patterns when paired with site-specific morphometric and ecological data.
PDF
