Search for: All records

This lake metabolism data was collected by HOBO Temperature loggers and miniDOT loggers that were deployed at Mirror Lake Central Buoy over the deepest part of the lake (11m) on 2023-08-23. HOBO loggers were deployed vertically at depths 0.25m, 2m, and 4m, and miniDOT loggers were deployed vertically at depths 0.5m, 1m, and 6m. Sensors were tied to nylon climbing rope at these different depths and anchored to a buoy. Loggers were later removed on 2023-09-08. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Expanded availability of estimates of ecosystem metabolism and gas exchange from the worlds streams and rivers is rapidly revising estimates of river contributions to global carbon budgets. Here, we present estimates of gross primary production, ecosystem respiration, and gas exchange from 27 streams and rivers across North America, including Puerto Rico, using data from the National Ecological Observatory Network (NEON). Further, we explore how aggregating and processing input data infuences model outputs, expanding the methodological knowledge in approaching sensor collection and manipulation for ecosystem-scale modelling. We apply flters to input data to determine how diferent approaches to quality control of raw data infuence the quantity and precision of estimates of ecosystem metabolism. Model estimates are high priority measures of ecosystem function that integrate additional NEON data products that will allow further understanding of stream and river biogeochemistry and ecosystem function across time and space. 

This dataset comprises daily images positioned to view streams above the weirs at Hubbard Brook for watersheds 1, 2, 3, 4, 5, 6, and 9. Cameras are programmed to take one image per day at ~12:00 pm ET. Each file is timestamped with the image metadata, but also within the file name, and structured to enable temporal trend analysis for end-users. The cameras used are BUSHNELL model number 119R3, and data are collected on SIM cards and manually downloaded every six months. Data gaps are minimal and generally associated with battery failures. These data are designed to capture stream dynamics over time for the purpose of visual pattern analysis, environmental monitoring, and machine learning applications. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

The pace and trajectory of ecosystem development are governed by the availability and cycling of limiting nutrients, and anthropogenic disturbances such as acid rain and deforestation alter these trajectories by removing substantial quantities of nutrients via titration or harvest. Here, we use six decades of continuous chemical and hydrologic data from three adjacent headwater catchments in the Hubbard Brook Experimental Forest, New Hampshire—one deforested (W5), one CaSiO3-enriched (W1), and one reference (W6)—to quantify long-term nutrient and mineral fluxes. Acid deposition since 1900 drove pronounced depletion and export of base cations, particularly calcium, across all watersheds. Experimental deforestation of W5 intensified loss of biomass and nutrient cations and triggered sustained increases in streamwater pH, Ca2+, and SiO2 exports over nearly four decades, greatly exceeding the effects of direct CaSiO3 enrichment in both duration and magnitude. We detect no long-term changes in water yield or water flow paths in the experimental watersheds, and we attribute this multidecadal increase in weathering rates following deforestation to biological responses to severe nutrient limitation. Our evidence suggests that in the regrowing forest, plants are investing photosynthate into belowground processes that amplify mineral weathering to access phosphorus and micronutrients, consequently elevating the export of less limiting elements present in silicate parent material. Throughout decades of forest regrowth, enhanced biotic weathering has continued to deplete the acid buffering capacity of the terrestrial ecosystem while the export of weathering products has elevated the pH of the receiving stream. 

Dissolved organic carbon (DOC) export from watersheds by streams is an important, changing component of the global carbon cycle. We examined the controls on DOC export by quantifying changes in the DOC concentration-discharge relationship from 1992 through 2022 for nine forested headwater catchments at the Hubbard Brook Experimental Forest in the northeastern United States. We observed a strong increase in the intercept of the log-log concentration-discharge relationship between 2005 and 2017 and a weak increase in the slope of that relationship between 2002 and 2021, along with seasonal and watershed-level differences. The intercept, which indicates the average stream DOC concentration at a given discharge, was strongly and inversely related to ionic strength of the soil solution as predicted by electrolyte solubility theory. This relationship varied among watersheds, perhaps because of soil pH. The intercept was not strongly related to annual precipitation or air temperature. DOC export ranged from 13 to 153 kg C ha-1 y-1 among study watersheds and years, and was correlated with annual precipitation and discharge. Historical data suggest that DOC export has probably increased over the past 50 years, likely due both to increases in precipitation and runoff and to increases in the intercept and slope of the concentration-discharge relationship. Our results suggest the potential for long-term legacy effects of acidification on DOC solubility and stream DOC concentrations in acid-sensitive watersheds, despite reductions in acid deposition, as mineral weathering slowly replenishes the ionic strength of soil solutions. 

Stream bryophytes (mosses and liverworts) are widely recognized as important macroinvertebrate habitats, but their overall role in the stream ecosystem, particularly in nutrient cycling, remains understudied. Hubbard Brook Experimental Forest in New Hampshire, USA, contains some of the most extensively researched streams in the world, yet few studies mention their bryophytes. Perhaps this is because early estimates place bryophyte coverage in these streams at an insignificant 2%. However, data from 2019 show that contemporary coverage ranges from 4 to 40% among streams. To investigate how stream bryophyte cover may be changing over time and influencing stream nutrient stocks, we conducted field surveys, measured the mass of organic and inorganic bryophyte contents, and quantified nutrient uptake with bottle incubations of bryophyte mats. This study marks a novel attempt to map stream bryophyte coverage with estimates of C, P, and N stocks and fluxes. From our 2022 field surveys, we found that median bryophyte coverage varied across streams in the same catchment (0–41.4%) and shifted from just 3 y prior. We estimate that these bryophyte mats stored between 14 and 414 g of organic matter per m2 of stream in the form of live biomass and captured particulates. Within 12 h of light incubation, 35 out of 36 bryophyte clump samples sorbed peak historical water-column concentrations of PO43– as measured in the Hubbard Brook stream chemistry record. In Bear Brook, our scaled estimate of bryophyte mat NO3– uptake (2.3 g N/y) constitutes a substantial portion of previously estimated whole-stream NO3– uptake (12 g N/y). Cumulatively, our data demonstrate that bryophytes and their associated mineral substrates and biota—known as the bryosphere—are crucial in facilitating headwater stream nutrient cycling. These bryospheres may contribute significantly to interannual variability in stream nutrient concentrations within nutrient-poor streams, especially in climate-sensitive regions. 

Abstract. Quantifying continuous discharge can be difficult, especially for nascent monitoring efforts, due to the challenges of establishing gauging locations, sensor protocols, and installations. Some continuous discharge series generated by the National Ecological Observatory Network (NEON) during its pre- and early-operational phases (2015–present) are marked by anomalies related to sensor drift, gauge movement, and incomplete rating curves. Here, we investigate the potential to estimate continuous discharge when discrete streamflow measurements are available at the site of interest. Using field-measured discharge as truth, we reconstructed continuous discharge for all 27 NEON stream gauges via linear regression on nearby donor gauges and/or prediction from neural networks trained on a large corpus of established gauge data. Reconstructions achieved median efficiencies of 0.83 (Nash–Sutcliffe, or NSE) and 0.81 (Kling–Gupta, or KGE) across all sites and improved KGE at 11 sites versus published data, with linear regression generally outperforming deep learning approaches due to the use of target site data for model fitting rather than evaluation only. Estimates from this analysis inform ∼199 site-months of missing data in the official record, and can be used jointly with NEON data to enhance the descriptive and predictive value of NEON's stream data products. We provide 5 min composite discharge series for each site that combine the best estimates across modeling approaches and NEON's published data. The success of this effort demonstrates the potential to establish “virtual gauges”, sites at which continuous streamflow can be accurately estimated from discrete measurements, by transferring information from nearby donor gauges and/or large collections of training data. 

This is the data and code associated with "Stream bryophytes promote 'cryptic' productivity in highly oligotrophic headwaters. Recent observations document increased abundance of algae in the headwater streams of Hubbard Brook Experimental Forest (HBEF). It is possible that this 'greening up' of HBEF streams may be due to climate change with rising temperatures, altered terrestrial phenology, and shifting hydrologic regimes. Alternatively, stream 'greening' could be due to the slow recovery of stream chemistry from decades of acid rain, which have led to rising stream water pH, declining concentrations of toxic Al3+, and extremely low solute concentrations. Three years of weekly algal measurements on contrasting substrates, 6 nutrient enrichment experiments reveal important new insights about the interactions between these two groups of autotrophs. We predicted that light availability, hydrologic disturbance and nutrient limitation were all important determinants of algal biomass in streams. To evaluate the relative strength and hierarchy of these limiting factors, we used nutrient diffusing substrates to investigate the role of nutrients for algae and compared algal accrual rate on artificial rock vs. moss substrates in stream channels vs. weir ponds to assess the role of hydrologic disturbance and scour. Our surveys and experiments spanned across seasons and local light regimes. Algal biomass was substantially higher in protected weir ponds than in stream channels, and in both habitats, algal biomass was substantially higher on artificial moss substrates than on tiles. Taken together, these results suggest that moss can provide physical protection from flood scour. Algal biomass instream on both substrate types was higher in high light seasons (pre-leaf out) and well-lit habitats indicating strong light limitation. Results from a series of 6 nutrient diffusing substrate experiments over the course of 2 years provided little evidence of nutrient limitation instream. The most striking finding of our investigation is the previously unsuspected role of stream bryophytes in providing critical refugia for algae in these steep, heavily shaded and oligotrophic headwaters. Shifts in stream productivity over time are likely to be closely tied to changes in bryophyte cover. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Abstract Accurately estimating stream discharge is crucial for many ecological, biogeochemical, and hydrologic analyses. As of September 2022, The National Ecological Observatory Network (NEON) provided up to 5 years of continuous discharge estimates at 28 streams across the United States. NEON created rating curves at each site in a Bayesian framework, parameterized using hydraulic controls and manual measurements of discharge. Here we evaluate the reliability of these discharge estimates with three approaches. We (1) compared predicted to observed discharge, (2) compared predicted to observed stage, and (3) calculated the proportion of discharge estimates extrapolated beyond field measurements. We considered 1,523 site-months of continuous streamflow predictions published by NEON. Of these, 39% met our highest quality criteria, 11% fell into an intermediate classification, and 50% of site-months were classified as unreliable. We provided diagnostic metrics and categorical evaluations of continuous discharge and stage estimates by month for each site, enabling users to rapidly query for suitable NEON data.