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Soil atmosphere fluxes of the trace gases; carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) have been measured at several locations at the Hubbard Brook Experimental Forest (HBEF) including 1) the "freeze" study reference plots that provide contrast between stands dominated (80%) by sugar maple versus yellow birch and low and high elevation areas, 2) the Bear Brook Watershed where trace gas sampling is coordinated with long-term monitoring of microbial biomass and activity and 3) watershed 1 where trace gas sampling locations were co-located with long-term microbial biomass and activity monitoring sites that are located near a subset of the lysimeter sites established for the calcium addition study on this watershed. This dataset contains the Watershed 1 and Bear Brook data. Freeze plot trace gas can be found in: https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-hbr&identifier=251. 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. 

Long-term monitoring of soil nitrate (NO3-) and ammonium (NH4+) concentrations, microbial biomass carbon (C) and nitrogen (N) content, microbial respiration, potential nitrification and N mineralization rates, pH, and denitrification potential has been ongoing at the Hubbard Brook Experimental Forest since 1994. Samples have been collected in the Bear Brook Watershed (west of Watershed 6) beginning in 1994. In 1998, our sampling regime was extended to Watershed 1 in an effort to monitor and quantify microbial response to a whole-watershed calcium addition. 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. 

We appear to be at a shining moment for interactions between soils and society. Popular interest in soils has increased along with interests in urban gardening, carbon sequestration, recognition of the vast biodiversity in soils, and the realisation that soils are a finite resource whose degradation has serious consequences. This increase in interest creates both opportunities and challenges for soil science. While there is great potential for increasing the diversity of people involved with soil science, key scientific and communication challenges need to be addressed for interactions between soils and society to be useful and productive. Here, I present case study issues on the mechanisms and limitations of carbon sequestration in soils and the need to restore and/or create new soils for specific uses, including urban agriculture and green infrastructure, to illustrate the opportunities and challenges associated with new societal interest in soil science. Addressing these issues requires advances in both basic and applied science, new participatory approaches to the design, execution, and interpretation of research, collaboration with multiple disciplines, including the social sciences, and improvements in the two‐way flow of information between science and society. Careful attention to these issues will attract new people to soil science, advance awareness of the importance of and threats to soils across the globe, and produce improvements in the quality of life for diverse human populations. 

Abstract. Late Cretaceous clays exposed at sites located on the north shore of Long Island, New York, USA, were sampled to explore questions about how contemporary factors and processes interact with ancient geological materials that are often assumed to not be biologically active. Chemically and biologically catalyzed weathering processes have produced multi-colored clays belonging to the kaolin group with inclusions of hematite, limonite, and pyrite nodules. We sampled exposed clays at three sites to address three questions: (1) do these exposed clays support significant amounts of microbial biomass and activity, i.e., are they alive? (2) Do these clays support significant nitrogen (N) cycle activity? (3) Are these clays a potential non-anthropogenic source of reactive N in the contemporary landscape? Samples were analyzed for total carbon (C) and N content, microbial biomass C and N content, microbial respiration, organic matter (OM) content, potential net N mineralization and nitrification, soil nitrate (NO3-) and ammonium (NH4+) content, and denitrification potential. Results strongly support the idea that ancient geologic materials play a role in contemporary N and C cycling in the Critical Zone. Respiration (average 4.098 µg C g−1d−1) was detectable in all samples and was strongly correlated to OM, indicating a living microbial community on the clays. There was evidence of an active N cycle. Higher levels of denitrification potential (average 1.376 µg N g−1 d−1) compared to both potential net nitrification (average 0.061 µg N g−1 d−1) and potential net N mineralization (average 0.144 µg N g−1 d−1) indicate that these clays act more as a sink rather than as a source of reactive N in the landscape. 

Declining nitrogen (N) availability relative to plant demand, known as N oligotrophication, is a widespread phenomenon that has been particularly well documented in northern hardwood forests of the northeast U.S. It is hypothesized that later fall senescence contributes to this trend by increasing tree resorption of N, resulting in higher carbon:nitrogen ratios (C:N) in litterfall and reduced N availability in soil. To examine the effects of litterfall C:N on soil N cycling, we conducted a litter quality manipulation experiment comparing low C:N and high C:N litter with native litter along an elevation and aspect gradient at Hubbard Brook Experimental Forest, NH, USA. We found that potential net ammonification and mineralization rates were positively correlated with litter N and negatively correlated with litter C:N under high C:N litter, but these relationships were not present under native or low C:N litter. Differences in nitrate pools and net mineralization rates between high- and low-quality litter treatments were greater at colder sites, where native litterfall tends to have lower C:N than at low-elevation sites. Together, these results demonstrate that higher C:N litter and a warming climate may contribute to N oligotrophication through effects on microbially driven N cycling rates in organic soils. 

Abstract Urbanization profoundly impacts biodiversity and ecosystem function, exerting an immense ecological filter on the flora and fauna that inhabit it, oftentimes leading to simplistic and homogenous ecological communities. However, the response of soil animal communities to urbanization remains underexplored, and it is unknown whether their response to urbanization is like that of aboveground organisms. This study investigated the influence of urbanization on soil animal communities in 40 public parks along an urbanization gradient. We evaluated soil animal abundance, diversity, and community composition and related these measures to urban and soil characteristics at each park. The most urbanized parks exhibited reduced animal abundance, richness, and Shannon diversity. These changes were influenced by many variables underscoring the multifaceted influence of urbanization on ecological communities. Notably, contrary to our expectation, urbanization did not lead to community homogenization; instead, it acted stochastically, creating unique soil animal assemblages. This suggests that urban soil animal communities are concomitantly shaped by deterministic and stochastic ecological processes in urban areas. Our study highlights the intricate interplay between urbanization and soil animal ecology, challenging the notion of urban homogenization in belowground ecosystems and providing insight for managing and preserving belowground communities in urban areas. 

Snow depth, soil frost depth and snow water content have been measured at several locations at the Hubbard Brook Experimental Forest (HBEF). In October 2010, as part of a study of the relationships between snow depth, soil freezing and nutrient cycling (http://www.ecostudies.org/people_sci_groffman_snow_summary.html), we established 6 20 x 20-m plots (intensive plots) and 14 10 x 10-m plots (extensive plots) following an elevation gradient, with eight of the plots facing north and twelve facing south. Snow and frost depth, and snow water equivalent sampling started in December 2010. Measurements on the extensive plots ended at the conclusion of snow coverage in spring, 2012. Measurements at the 6 intensive plots are ongoing and measurement frequency was increased from approximately bimonthly to approximately weekly beginning in the 2019-2020 snow cover season. 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.