Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • An examination of environmental factors that influence the composition of diatom communities in northern hardwood streams (USA)
Title: An examination of environmental factors that influence the composition of diatom communities in northern hardwood streams (USA)
Headwater streams draining northern hardwood forests are vulnerable to environmental pressures, including climate change, atmospheric deposition, land-use changes, and recreational impacts. These streams play a crucial role in the forest ecosystem by influencing nutrient dynamics, water quality, and serving as refugia for aquatic species. This study focuses on epiphytic diatom communities that colonize bryophytes within Hubbard Brook Experimental Forest (HBEF), where extensive ecological research exists but with limited data on diatom community composition. Bryophytes provide stable, nutrient-rich microhabitats that support diatom growth, offering refugia from flood scour and accumulating stream sediments, making them useful for studying diatom dynamics. We compared diatom communities colonizing artificial bryophytes across seven streams weir ponds in HBEF in New Hampshire and explored the influence of various environmental factors on species richness. Distinct diatom communities were observed, along with increased species richness under higher light exposure. Further analysis reveals significant variability in diatom communities driven by watershed-specific environmental conditions and temporal changes. A total of 86 diatom taxa spanning 43 genera were identified, with species presence significantly associated with environmental variables such as light intensity (lux), dissolved organic carbon, pH, and total dissolved nitrogen. These findings reinforce the value of Diatoms are sensitive environmental indicators in this study, provide useful insights into ecosystem health and resilience of streams flowing through northern hardwood forests in the face of environmental stressors.  more » « less
Award ID(s):
2401760 2224545
PAR ID:
10599349
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Environmental and Sustainability Indicators
Volume:
27
Issue:
C
ISSN:
2665-9727
Page Range / eLocation ID:
100697
Subject(s) / Keyword(s):
Bioindicators Diatoms Freshwater ecosystems Hubbard Brook Experimental Forest Light limitation Bryophyte Environmental drivers
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; (, Environmental Data Initiative)
    This dataset contains species richness data for epiphytic diatom communities collected from weir ponds in seven headwater streams within the Hubbard Brook Experimental Forest (HBEF) in New Hampshire between 2018 and 2021. Diatom samples were gathered using artificial bryophyte substrates, deployed in weir ponds to mimic natural diatom habitats. Species richness was quantified by identifying diatom taxa to the lowest possible taxonomic level, with 86 taxa spanning 43 genera recorded. This dataset represents the first comprehensive classification of diatom communities at HBEF, providing a baseline for future studies in this ecosystem. Environmental variables, including light availability, dissolved organic carbon, total dissolved nitrogen, and pH, were concurrently measured to assess their influence on diatom community composition. The light (lux) data used in this study is openly available in the EDI Data Portal at https://doi.org/10.6073/pasta/0f40b75b299494d736645d940fa2b5a4. The chlorophyll-a data and analysis methodology are available at https://doi.org/10.6073/pasta/7fa32d94240fc7780d62cb7e65eafdb2. Reach characteristics were sourced from the EDI Data Portal at https://doi.org/10.6073/pasta/3e4b95149245341d522383bba51de7c7. This study provides valuable insights into the relationships between environmental factors and diatom diversity in northern hardwood forest streams, aiding ecological monitoring and bioindicator studies. 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. 
    more » « less
  2. ; ; ; ; (, Environmental Data Initiative)
    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. 
    more » « less
  3. ; ; ; (, Ecosystems)
    Riparian forests influence stream ecosystems by controlling light availability, nutrient inputs and adding large wood (LW). While many functions of in-stream LW are well studied, there is limited research on their carbon storage potential, especially in eastern North America. Due to forest recovery following historic clearing regionally, riparian forest structure is changing, with implications for LW recruitment, accumulation and carbon dynamics. To better understand the LW carbon pool and relationships with riparian forest structure, we collected data on the forest and in-stream LW in headwater streams in the mature, northern hardwood Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA. To understand how in-stream carbon storage will change as these second-growth forests develop, we collected comparison data at streams in old-growth forests of the Adirondacks of New York State. Streams at the HBEF contained 7.5 Mg C/ha in LW (SD = 5.8 Mg C/ha), exhibiting substantial variation within and between sites. This variation is linked to heterogeneity in riparian forest structure, especially the large tree basal area. Our data suggest the storage potential of stream LW will increase as riparian forests age, with old-growth stands storing 23.8 Mg C/ha as LW (SD = 9.8). This provides a first assessment of the LW carbon pool in the region and the biotic factors that influence this storage. The positive relationship between LW carbon and large trees, and the increased storage in old-growth forests supports conservation and management that promote large trees and old forests in riparian zones. Such practices may improve the value of in-stream LW carbon as a natural climate solution. 
    more » « less
  4. ; ; ; ; (, Limnology and Oceanography)
    Sponseller, Ryan (Ed.)
    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, altering terrestrial phenology, and shifting hydrologic regimes. Alternatively, stream “greening” could be from the slow recovery of stream chemistry after decades of acid rain, which has led to rising pH, declining concentrations of toxic Al3+, and low solute concentrations. Four years of weekly algal measurements on artificial moss and ceramic tiles, along with six nutrient enrichment experiments, revealed new insights about the interactions between these two autotrophs. We found that in protected weir ponds and in stream channels, algal biomass was higher on artificial moss substrates than on tiles—with this effect amplified in the stream channels. These results suggest that bryophytes can provide physical protection from flood scour or may trap nutrients to support algal growth. In stream channels, algal biomass was higher in well‐lit habitats and time periods indicating strong light limitation. We only measured nitrogen and phosphorus limitation of algal biomass in nutrient enrichment experiments conducted within weir ponds, with higher light availability and lower flow. By comparison, results from the remaining four instream experiments provided little evidence for nutrient limitation, with only one trial showing increased algal growth in response to nutrient addition. The most striking implication of our study is the role of bryophytes in providing refugia, and potentially nutrients, to algae in shaded and oligotrophic headwater streams. 
    more » « less
  5. ; ; (, Environmental Data Initiative)
    The Multiple Element Limitation in Northern Hardwood Ecosystems (MELNHE) project studies N and P acquisition and limitation of forest productivity through a series of nutrient manipulations in northern hardwood forests. This data set is published in support of a manuscript titled "Nitrogen and phosphorus co-limitation of forest growth in northern hardwood forests" and includes data and code used in the analysis. The primary diameter breast height dataset can be found in: Fisk, M.C., R.D. Yanai, and T.J. Fahey. 2025. Tree DBH response to nitrogen and phosphorus fertilization in the MELNHE study, Hubbard Brook Experimental Forest, Bartlett Experimental Forest, and Jeffers Brook ver 2. Environmental Data Initiative. https://doi.org/10.6073/pasta/fb8f8d5b903627bee9ad6aa4c32f2289. Additional detail on the MELNHE project, including a datatable of site descriptions and a pdf file with the project description and diagram of plot configuration can be found in this data package: https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-hbr&identifier=344. 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. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email