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As the interface between plants and soil, the organic horizon is the foundation of forest ecosystems. Two potential predictors of O-layer properties, vegetation and mineral soil type, are difficult to separate because they typically covary. We conducted a factorial study involving four canopy tree species and two soil types with distinctly different hydrology and topographic position to parse patterns in chemistry and microbiota of the O-layer in a north-temperate deciduous forest. There were frequent strong effects of tree species. White ash frequently differed from the other trees: e.g., lower cation exchange capacity and exchangeable acidity, thinner Oi layer, lower %C and C:N, and, from phospholipid fatty acids, more AM fungi and less gram+ bacteria. These patterns, presumably due to species-specific attributes of leaf litter quality, root exudates, and microbial associations, must arise over decades, given that the stands in the study age between 85 and 100 years. We also found patterns in the O-layer related to underlying soil type, independent of tree species: e.g., Bh podzols, compared to Typical podzols, had higher trace metals, thicker Oa layer, and more AM fungi. Relations between mineral soil type and the organic layer, which were larger than expected, could arise because landscape features that influence hydrology and therefore soil formation over millennia also influence biogeochemistry of the organic layer over decades. It could also involve bioturbation by organisms across horizons. There is basic and applied value in models that can predict properties of the O-layer based on vegetation and soil types. 

Numbers and lengths of Lepidoptera larvae (caterpillars, all species) were censused on shrub level foliage at biweekly intervals from late May/early June through late July/early August each year. Measurements were conducted on the Main bird plot in the Hubbard Brook Experimental Forest and on three additional plots within the White Mountain National Forest from 1986-1997. 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. 

Mycorrhizal fungi are important drivers of soil organic matter dynamics, but it can be difficult to isolate the effects of the fungi themselves from co-varying traits of their host trees. For example, many trees with an evergreen leaf habit associate with ectomycorrhizal (ECM) fungi, while many deciduous tree species associate with arbuscular mycorrhizal (AM) fungi. Because leaf habit influences the quantity and quality of organic matter inputs to soil, it is often an important factor in soil carbon and nitrogen dynamics, and thus can mask the effects of mycorrhizal fungi on soil organic matter processes. We evaluated how tree mycorrhizal associations and leaf habit separately influence the amount and composition of mineral-associated organic matter (MAOM) and particulate organic matter (POM) in forest soils in New Hampshire and Vermont, USA. We measured carbon (C) and nitrogen (N) concentrations and C:N ratios of three soil density fractions beneath six tree species that vary in mycorrhizal association and leaf habit. We found lower concentrations of MAOM C and N beneath evergreen vs. deciduous trees, but only for tree species associating with AM fungi. Further, MAOM C:N was higher beneath evergreen trees and beneath trees with ECM fungi rather than AM fungi. These results add to the growing body of support for mycorrhizal fungi as mediators of soil organic matter dynamics, suggesting that the MAOM fraction is more sensitive to leaf habit beneath AM-associated versus ECM-associated trees. Because MAOM decomposition is thought to be less responsive than POM decomposition to changes in soil temperature and moisture, differences in the tendency of AM- and ECM-dominated forests to support MAOM formation and persistence may lead to systematic differences in the response of these forest types to ongoing climate change. 

As the interface between plants and soil, the organic horizon is the foundation of forest ecosystems. Two potential predictors of O-layer properties, vegetation and mineral soil type, are difficult to separate because they typically covary. We conducted a factorial study involving four canopy tree species and two soil types with distinctly different hydrology and topographic position to parse patterns in chemistry and microbiota of the O-layer in a north-temperate deciduous forest. 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. 

Relations among territoriality, abundance and habitat suitability are fundamental to the ecology of many animal populations. Theory suggests two classes of possible responses to increasing abundance in territorial species: (1) the ideal free distribution (IFD), which predicts smaller territory sizes and decreased fitness as individuals adaptively pack into suitable habitats, and (2) the ideal despotic distribution (IDD), which predicts stable territory sizes and fitness in preferred habitats for dominant individuals and increased use of marginal habitats, reduced fitness and changes in territory sizes for subordinate individuals. We analysed the territory sizes and locations of seven migratory songbird species occupying a 10‐ha plot in the Hubbard Brook Experimental Forest, New Hampshire, USA over a 52‐year period. Species varied in abundance over years from twofold to 22‐fold, and all species displayed clear patterns of habitat preference within the study plot. Consistent with IFD, and contrary to IDD, territory sizes decreased with local abundance for all species, irrespective of habitat preferences. There was at least a twofold variation in territory size within years. Conformity of territory size to predictions of the IFD argues for the efficacy of territorial defence in songbirds and has general consequences for population dynamics. 

In this study, we analyzed territory sizes of seven migratory songbirds occupying a 10-hectare plot in the Hubbard Brook Experimental Forest, New Hampshire, USA over a 52-year period (1969-2021). All species varied in abundance over the duration of the study, some dramatically. Changes in territory sizes were inversely related to changes in abundance within the study plot despite differences in habitat preference, supporting the ideal free distribution. Territory sizes varied two-fold within a year across species. Results contribute to understanding how variation in territory size relates to 1) how habitat use changes with bird abundance and 2) the evolution of territory size. This dataset includes data, R code, and spatial files supporting this study. 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. Associated datasets in the data catalog: Holmes, R.T., N.L. Rodenhouse, and M.T. Hallworth. 2022. Bird Abundances at the Hubbard Brook Experimental Forest (1969-present) and on three replicate plots (1986-2000) in the White Mountain National Forest ver 8. Environmental Data Initiative. https://doi.org/10.6073/pasta/6422a72893616ce9020086de5a5714cd (Accessed 2023-12-17). Zammarelli, M.B. and R.T. Holmes. 2023. Hubbard Brook Experimental Forest: 10-ha bird plot territory maps, 1969 - 2021 ver 1. Environmental Data Initiative. https://doi.org/10.6073/pasta/df93595ba8df60570d472f6e6f58839e (Accessed 2024-01-11). 

In this study, we analyzed territory sizes of seven migratory songbirds occupying a 10-hectare plot in the Hubbard Brook Experimental Forest, New Hampshire, USA over a 52-year period (1969-2021). All species varied in abundance over the duration of the study, some dramatically. Changes in territory sizes were inversely related to changes in abundance within the study plot despite differences in habitat preference, supporting the ideal free distribution. Territory sizes varied two-fold within a year across species. Results contribute to understanding how variation in territory size relates to 1) how habitat use changes with bird abundance, 2) the evolution of territory size, and 3) the role of territoriality in population dynamics. This dataset includes data, R code, and spatial files supporting this study. 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. Associated datasets in the data catalog: Holmes, R.T., N.L. Rodenhouse, and M.T. Hallworth. 2022. Bird Abundances at the Hubbard Brook Experimental Forest (1969-present) and on three replicate plots (1986-2000) in the White Mountain National Forest ver 8. Environmental Data Initiative. https://doi.org/10.6073/pasta/6422a72893616ce9020086de5a5714cd (Accessed 2023-12-17). Zammarelli, M.B. and R.T. Holmes. 2023. Hubbard Brook Experimental Forest: 10-ha bird plot territory maps, 1969 - 2021 ver 1. Environmental Data Initiative. https://doi.org/10.6073/pasta/df93595ba8df60570d472f6e6f58839e (Accessed 2024-01-11). 

During 2016 - 2023, during the bird breeding season, we collected 99,778 files of bioacoustic recordings in and near the Hubbard Brook Experimental Forest in New Hampshire. Here, we provide a manifest of the sound files. Most files are one-hour recordings collected at 32 kHz and saved in FLAC format (~ 25 MB per file, ~ 13 TB total). Typical recording configuration was 05:00 - 08:00 and 17:30 - 20:30 local time. The full sound files have been saved in three respositories: two copies at Dartmouth College (Ayres lab) and one copy at the Macauley Library, Cornell Laboratory of Ornithology. The full sound files are available upon request. The file attributes within the manifest include date, start time, and recorder group: e.g., Main, 10ha, Oven, VW, AshBirch, and Ridge. Each recorder group had 5 - 20 recorders at plots separated by >100 m. Coordinates of each recorder are associated with plot names within metadata. The bird species expected to occur in these recordings are those from Holmes et al. (2021). 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. Holmes, R., S. Sillett, and M. Hallworth. 2021. Bird species recorded within the Hubbard Brook Experimental Forest and vicinity (1963-2020; updated January 2021). ver 1. Environmental Data Initiative. https://doi.org/10.6073/pasta/da6cbb1ed8142d52a9d72762983742d8 (Accessed 2024-10-24). 

Arthropods are active during the winter in temperate regions. Many use the seasonal snowpack as a buffer against harsh ambient conditions and remain active in a refugium known as the subnivium. While the use of the subnivium by insects and other arthropods is well-established, far less is known about winter community composition, abundance, biomass, and diversity and how these characteristics compare with the community in the summer. Understanding subnivean communities is especially important given observed and anticipated changes in snowpack depth and duration with changing climate. We studied winter and summer insects and other arthropods using pitfall trapping in northern New Hampshire, where snowpack is still relatively intact. We found that compositions of the subnivium and summer arthropod communities differed. The subnivium arthropod community featured moderate levels of richness and other measures of diversity that tended to be lower than in the summer community. More striking, the subnivium community was much lower in overall abundance and biomass than the summer community. Interestingly, some groups and species of arthropods were dominant in the subnivium but either rare or absent in summer collections. These putative “subnivium specialists” included one spider (order: Araneae), Cicurina brevis (Emerton, 1890), and three rove beetles (order: Coleoptera, family: Staphylinidae) Arpedium cribratum Fauvel, 1878, Lesteva pallipes LeConte, 1863, and Porrhodites inflatus (Hatch, 1957). This study provides a detailed account of the subnivium arthropod community, presents novel concepts, and establishes baseline information on arthropod communities in the North American northeastern temperate forest.