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openCC0Jun 2022View details →

Long-term monitoring of stormwater runoff and water quality in urbanized watersheds of the greater Phoenix metropolitan area, ongoing since 2008

Urbanization alters dramatically watershed ecosystem processes. Land-use change and anthropogenic activities contribute to increased inputs of nutrients and other materials, while changes to land cover alter hydrology and the corresponding movement of materials. These changes have ramifications for both watershed processes and downstream systems. The impacts of urbanization on aquatic systems are well-studied, and frequently encapsulated in the ‘urban stream syndrome’ (Walsh et al. 2005) that describes, among others, increased nutrient loading and stream flashiness. However, there is some evidence that aridland cities behave differently (Grimm et al. 2004, 2005), and the complex dynamics among catchment characteristics, storm attributes, and runoff in highly urbanized settings of the arid Southwest remains poorly understood. To enhance our understanding of stormwater dynamics and watershed functioning in aridland, urban environments, the Central Arizona–Phoenix Long-Term Ecological Research (CAP LTER) program began monitoring stormwater runoff at the outflow of the Indian Bend Wash (IBW) in 2008. The IBW is a tributary to the Salt River in central Arizona, and is a major drainage within the greater Phoenix metropolitan area, encompassing much of the City of Scottsdale. A model of soft engineering, the IBW as it runs through much of the City of Scottsdale is comprised largely of a series of artificial lakes, parks, paths, golf courses, ball fields, and other non-structural elements designed with the dual roles of providing outdoor amenities to the City residents while serving as an effective flood water conveyance feature. A unique biogeochemistry of this novel system is detailed by Roach et al. (2008), and Roach and Grimm (2011). Stormwater sampling is conducted at numerous locations. The longest running sampling location is near the outflow of the IBW ~0.6 km above its confluence with the Salt River. The sampling location coincides with a permanent USGS gauging sta

Deer and Moose Browsing in Hemlock Removal Experiment at Harvard Forest 2008

Hemlock decline in New England is caused by direct and indirect effects of invasion of the hemlock woolly adelgid. Direct damage from the insect is causing gradual mortality of hemlock, and widespread harvesting of hemlock in advance of mortality, in contrast, causes immediate mortality and removal of biomass from the site. Although both processes affect thousands of acres of forest annually we have only a limited understanding of their effects on forest ecosystem function and productivity and the nature of the subsequent forest community. We anticipate that harvesting will yield different consequences than gradual mortality from the insect. Therefore we designed an experiment to simulate these contrasting impacts, by logging or girdling hemlock stands. Results from the experimental treatments will be compared to the changes observed in forests that are being infested by the adelgid, and can also be included in integrated analyses of a suite of large experiments that form a core component of the Harvard Forest LTER program. Deer and moose foraging can play a key role in shaping forest regeneration after disturbance in temperate forest. In 2008, we initiated a browsing survey of woody stems in the Simes hemlock removal experiment plots. There are regular moose sightings in the study area, and moose pellets are commonly found within the plots. Also, extensive browsing of tree regeneration in the logged plots was noted starting in 2007. Sampling of the 8 study plots was completed in Summer 2008. The next sampling is tentatively scheduled for Summer 2013.

Detection Histories for Hemlock Woolly Adelgid Infestations at Cadwell Forest in Pelham MA 2008

Monitoring programs increasingly are used to document the spread of invasive species in the hope of detecting and eradicating low-density infestations before they become established. However, interobserver variation in the detection and correct identification of low-density populations of invasive species remains largely unexplored. In this study, we compare the abilities of volunteer and experienced individuals to detect low-density populations of an actively spreading invasive species and we explore how interobserver variation can bias estimates of the proportion of sites infested derived from occupancy models that allow for both false negative and false positive (misclassification) errors. We found that experienced individuals detected small infestations at sites where volunteers failed to find infestations. However, occupancy models erroneously suggested that experienced observers had a higher probability of falsely detecting the species as present than did volunteers. This unexpected finding is an artifact of the modeling framework and results from a failure of volunteers to detect low-density infestations rather than from false positive errors by experienced observers. Our findings reveal a potential issue with site occupancy models that can arise when volunteer and experienced observers are used together in surveys.

PhenoCam Images and Canopy Phenology at the Harvard Forest EMS Tower since 2008

The PhenoCam Network uses imagery from digital cameras to track vegetation phenology and seasonal changes in vegetation activity in diverse ecosystems across North America and around the world. Imagery is uploaded to the PhenoCam server at the University of New Hampshire, where it is made publicly available in near-real time, every 30 minutes from sunrise to sunset, 365 days a year. The data are processed using simple image analysis tools to yield a measure of canopy greenness, from which phenological metrics are extracted, characterizing the start and end of the growing season. These transition dates have been shown to align well with on-the-ground observations of tree phenology at Harvard Forest (HF003). Long-term PhenoCam data can be used to track the impact of climate variability and change on the rhythm of the seasons. This dataset contains one mid-day image for each camera. Please see the PhenoCam Network website (http://phenocam.sr.unh.edu) for more information and additional images.

20-Year Root Mass in Chronic Nitrogen Amendment Experiment at Harvard Forest 2008

Forests typically respond to nitrogen additions with increased productivity, hence a long-held paradigm was that chronic additions of anthropogenically-derived atmospheric deposition would have positive ecosystem effects. However, twenty years of work at the Harvard Forest Chronic N Deposition plots, and in other forest ecosystems as well, has shown that that this simplistic view is incomplete. For example, enhanced ammonium uptake increases soil acidity, leading to mobilization of aluminum, and loss of nutrient cations (e.g. Mg2+, Ca2+, and K+ ) all of which influence root mass, turnover, and activity. To address long-term impacts of N additions on forest root mass, we removed O-horizon (forest floor) samples from the Chronic N hardwood and red pine stands to quantify the total mass of roots. We found that long term N additions had contrasting results in the two forests. In the hardwood plots, total root mass (less than 2mm) increased from 0.167 + 0.026 (S.E.) kg m-2 in the control plot to 0.434 + 0.170 kg m-2 in the high N plots. In contrast, in the red pine stand, roots declined from 0.074 + 0.011 (S.E.) kg m-2 in the control plot to 0.031 + 0.016 kg m-2 in the high N plots. These data are in agreement with data for aboveground productivity at the Chronic N plots, which show stimulated growth in the hardwoods and severe growth declines and enhanced mortality in the pine stand.

Autumnal Litter Input in DIRT Litter Manipulation Experiment at Harvard Forest 2008

Climate change will alter forest ecosystem productivity, changing the quantity and quality of detrital inputs to soil and altering rates of soil organic matter (SOM) accumulation and stabilization. To examine changes in forest soil SOM pools, we have used the Detritus Input and Removal Treatments (DIRT) Project to alter organic matter input rates and sources (roots, leaves) to soils, allowing us to measure contributions of organic matter sources to long-term SOM storage at five temperate forests (Harvard Forest, HJ Andrews, Bousson (PA) Experimental Forest (BEF), U. Michigan Biological Station (UMBS), Síkfokut ILTER, Hungary). Organic matter inputs are altered by excluding or adding leaf inputs, or by excluding roots from forested plots. Soil respiration partitioning at HF, BEF, and UMBS shows that soil fertility controls the allocation of C to above- and belowground tissue. At UMBS, glacial outwash sandy soils are extremely low in N, and C released from root respiration plus root litter decomposition is 87% of total soil respiration. Conversely, at the N-rich BEF site, total belowground sources of CO2 are only 61% of soil respiration, with 47% attributed to root litter. These data suggest that at BEF, leaf litter, comprising only 39% of soil respiration, would be a more important source of long-term SOM than root litter. However, soil chemistry and radiocarbon data have shown us that long-term soil C storage is complex. The year 2010 represents the 20-year anniversary of the initiation of DIRT treatments at the Harvard Forest (2010), and we are therefore planning to conduct systematic sampling campaigns for a comprehensive study of changes in SOM quality after long-term manipulation of inputs. One objective is to quantify how 20 years of litter input alterations have affected SOM quantity and quality at the surface (0-20 cm) and deeper in the soil profile (20-100 cm). To uderstand these changes, we need to quantify the quantity and quality of aboveground litter inp

Allelopathy of Frangula Alnus to Native New England Wetland Vegetation at Harvard Forest 2008

Glossy buckthorn (Frangula alnus), an invasive shrub from Eurasia, colonizes both upland and mesic sites in New England, USA, reducing the growth and survival of native tree saplings and lowering species richness. Although a generalist, buckthorn thrives particularly well along river, pond, and wetland margins, which are traditional habitat for speckled alder (Alnus incana ssp. rugosa), a native nitrogen-fixing shrub. As buckthorn’s dense, monospecific growth is typical of allelopaths, we wondered whether it chemically suppresses the growth of alder and other indigenous shrubs. We thus propagated three native shrub species: Alnus incana ssp. rugosa, Viburnum dentatum and Spiraea latifolia, in invasive buckthorn and native dogwood (Cornus amomum) root and leaf mulch. After seven weeks, alder grown in buckthorn root demonstrated significantly smaller basal diameter than alder grown in buckthorn leaf or other mulches. Therefore, putative buckthorn allelopathy to alder likely occurs through root exudation instead of leaf litter effects. Meadowsweet grown in buckthorn mulch, in contrast, was taller, thicker, and had more numerous leaves than meadowsweet grown in native mulch. These species-specific effects point to allelopathy as a mechanism by which buckthorn changes the structure of native plant communities.

Soil Arthropods in Hemlock Removal Experiment at Harvard Forest 2008

In eastern North American forests, eastern hemlock (Tsuga canadensis) is a foundation species. As hemlock is lost from forests due to the invasive hemlock woolly adelgid (Adelges tsugae) and pre-emptive salvage logging, the structure of assemblages of species associated with hemlock is expected to change. We manipulated hemlock canopy structure at hectare scales to investigate the effects of hemlock death on assemblages of ants, beetles, and spiders in a New England forest. Relative to reference hemlock stands, both in situ death of hemlock and logging and removal of hemlock altered composition and diversity of beetles and spiders, and logging increased the species richness and evenness of ant assemblages. Species composition of ant assemblages in disturbed habitats was non-random relative to the regional species pool, but we found no evidence that interspecific competition shaped the structure of ant, beetle or spider assemblages, in either manipulated or intact forest stands. Environmental filtering by hemlock appears to maintain low levels of species richness and evenness in forest stands, suggesting that the loss of hemlock due to the hemlock woolly adelgid or human activities will not likely lead to extirpations of ant, beetle, or spider species at local scales.

Long-Term Impacts of the Hemlock Woolly Adelgid on Forest Carbon at Harvard Forest 2008-2011

The abundance of eastern hemlock (Tsuga canadensis) in eastern US forests has declined since the 1950s owing to the introduction of the non-native insect, hemlock woolly adelgid (HWA, Adelges tsugae). In southern New England, eastern hemlock is being replaced by the deciduous tree species, black birch (Betula lenta). To date there is little understanding of whether hemlock loss will fundamentally alter ecosystem C balance and component fluxes. In this study, we use a comparative approach to study potential changes in C fluxes and storage and N cycling associated with HWA-induced hemlock decline and replacement. The stands include primary- and secondary-growth hemlock forests (230 and 132 years old, respectively), recently disturbed stands (5 and 18 years old) that now have rapidly growing black birch saplings, and a mature black birch stand of age similar to the second-growth hemlock stand. We addressed the question of whether the quantity and distribution of C pools in black birch forests are the same as those found in the hemlock stands they replace and, if so, over what time scales. We found that if HWA did not infest hemlock stands in central MA, C stocks in these secondary stands could still increase by at least 30% over a period of 100 years. Girdling, intended to simulate HWA infestation, resulted in a large transfer of C from live biomass to coarse woody debris five years after treatment, but had little effect on total ecosystem C content. A former hemlock stand killed by HWA and now dominated by black birch saplings also had a large pool of highly decayed CWD and a rapidly aggrading C pool in live biomass. C pools in biomass in a mature, secondary growth black birch stand 135 years since pastureland abandonment were as large as those in a primary-growth hemlock stand 235 years of age. We also found that aboveground net primary production was higher in the aggrading black birch stand and significantly so at 18-years post-HWA compared to the secondary-hemlock

openJul 2025View details →

GLBRC Aboveground Plant Biomass at the Kellogg Biological Station, Hickory Corners MI (2008 to 2023), and the Arlington Research Station,Arlington, WI (2008 to 2014)

Dataset Abstract Aboveground biomass of BCSE herbaceous perennial crop treatments (G4 starting in 2021, G5-G7, G9-G10). Peak biomass samples were sorted to species from 2009-2017 but are left “unsorted” from 2018 onward. original data source http://lter.kbs.msu.edu/datasets/82

openCC (other)Dec 2022View details →

Fluxes project at North Temperate Lakes LTER: Predicting Peat Depth in a North Temperate Lake District 2008

Peat deposits contain on the order of 1/6 of the Earth's terrestrial fixed carbon (C), but uncertainty in peat depth precludes precise estimates of peat C storage. To assess peat C in the Northern Highlands Lake District (NHLD), a approximately 7000 square km region in northern Wisconsin, United States, with 20 percent peatland by area, we sampled 21 peatlands. In each peatland, peat depth (including basal organic lake sediment, where present) was measured on a grid and interpolated to calculate mean depth. Our study addressed three questions: (1) How spatially variable is peat depth? (2) To what degree can mean peat depth be predicted from other field measurements (water chemistry, water table depth, vegetation cover, slope) and/or remotely sensed spatial data? (3) How much C is stored in NHLD peatlands? Site mean peat depth ranged from 0.1 to 5.1 m. Most of the peatlands had been formed by the in-filling of small lake basins (terrestrialization), and depths up to 15 m were observed. Mean peat depth for small peat basins could be best predicted from basin edge slope at the peatland/upland interface, either measured in the field or calculated from digital elevation (DEM) data (Adj. R2 = 0.70). Upscaling using the DEM-based regression gave a regional mean peat depth of 2.1 plus or minus 0.2 m (including approximately 0.1 to 0.4 m of organic lake sediment) and 144 plus or minus 21 Tg-C in total. As DEM data are widely available, this technique has the potential to improve C storage estimates in regions with peatlands formed primarily by terrestrialization. Number of sites: 21 Sampling Frequency: once for each site

openCC (other)Dec 2022View details →

North Temperate Lakes LTER: Northern Wisconsin Lake Resident Survey 2005, 2008, 2012

The purpose of this survey was to understand what lake characteristics people value most, what activities they enjoy most, and what they expect for the future of northern Wisconsin lakes. Questions covered aspects such as the property search process individuals went through leading up to their purchase of lakeshore property in Vilas County WI, what activities the individual's household participate in on lakes in Vilas County WI, their attitude about the future of their lake, their perception of the current state of their lake, and lake qualities they would like improved on their lake. Demographics of the respondents and background information about their lake were also collected. Two types of surveying methodologies were used for this survey, one being an internet-based survey, while the other was a mail survey. Surveys were conducted in 2005 and repeated in 2008.

openCC (other)Dec 2025View details →

Pika demography data for west knoll and Indian Peaks wilderness, 2008 - ongoing.

Pikas are captured, anesthetized, marked with colored ear-tags, non-lethally sampled, and released at point of capture during June-October. Study sites include a gradient of elevation and slope aspect, allowing a comparative study of pika response to variation in climate and sub-surface microclimate. Daily variation in snow cover and sub-surface temperatures are measured using data loggers placed within the territories of marked pikas. Focal territories are revisited at least once to characterize available vegetation via transect sampling and at least annually to service data loggers and record pika survival. Samples collected for genetic and physiological studies include ectoparasites, blood, saliva, urine, feces and hair as well as records of sex, stage, reproductive status, weight, foot length and body temperature.

openCC0Jan 2022View details →

Phoenix, Arizona (USA) residential yard management and vegetation change over time: 2008-2019

This project sampled residential front yards in four Phoenix, AZ neighborhoods to address questions about how residential yard vegetation varies among neighborhoods and changes over time and in response to resident attitudes. Neighborhoods were located on an approximate north-to-south transect in the city of Phoenix and represented different dominant landscape types (xeric or mesic) and different socioeconomic conditions. The project originated in summer 2008, when approximately 100 parcels were selected in each of the four neighborhoods for front yard vegetation sampling. All yards which could be relocated and accessed in the summer of 2018 were resampled, and current residents were surveyed to understand their yard management motivations, attitudes, and changes made. Yards of 100 survey respondents were resampled a third time in 2019. Yard sampling primarily focused on yard woody vegetation identification, but also included ground cover, yard type of neighboring yards, and features such as fences, lighting, and social infrastructure. Social and yard survey data can be linked with unique identifiers provided in the datasets.

openCC (other)Aug 2025View details →

Multiple Element Limitation in Northern Hardwood Ecosystems (MELNHE): Soil respiration at Hubbard Brook Experimental Forest, Bartlett Experimental Forest and Jeffers Brook, central NH USA, 2008 - present

Abstract Soil respiration in 15 stands across 3 sites within the White Mountain National Forest was measured between 2008 and 2020. Stands included in the dataset are part of the Multiple Element in Northern Hardwood Ecosystems (MELNHE) study, a full-factorial NxP fertilization experiment. Pre- and post-treatment data are included, with treatment beginning in 2011. Soil temperature, soil moisture, and relative air humidity at the time of measurement were also recorded next to or above the soil respiration collar at the time of the soil respiration measurement. Having been cut between 1883 and 1990, stands are representative of different successional stages.

openCC (other)Jan 2025View details →

Multiple Element Limitation in Northern Hardwood Ecosystems (MELNHE): Foliar Chemistry 2008-2022 in Bartlett, Hubbard Brook, and Jeffers Brook

We are conducting nutrient manipulations in three study sites in the White Mountain National Forest in New Hampshire: Bartlett Experimental Forest, Hubbard Brook Experimental Forest, and Jeffers Brook. We monitored foliar chemistry in 13 of our stands (including HBCa and excluding C3) pre-treatment (2008-2010) and post-treatment (2014-2016 and 2021-22). In 2021-22, we also measured specific leaf area, leaf dry matter content, carbon isotope composition, and stomatal density. We found that foliar N concentrations were higher with N addition and foliar P concentrations were higher with P addition. More interestingly, P addition reduced foliar N concentrations and N addition reduced foliar P concentrations. Some interactive effects were observed (i.e. NxP, Species x N, Species x P, Species x N x P). This dataset contains pre- and post- treatment foliar chemistry and trait data, and data from the analysis of quality control standard samples. Changes to pre-treatment data from version 1 include switching white birch trees #8272 and #8252 in stand JBM plots 2 and 3 (8272 is now in the nitrogen plot and 8252 is now in the control plot), correcting the species of tree #1628 in stand HBCa plot 1 (changed from red maple to sugar maple) and tree #8457 in stand HBO plot 3 (changed from sugar maple to red maple), and updating nutrient concentrations for C8 plot 3 sugar maple trees #28 and #30 to include averages of subsamples re-run in 2022. Tree tags were also updated to the tag ID present during the 2023 tree inventory. 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

Sarracenia Purpurea Prey Capture at Harvard Forest 2008

We experimentally demonstrate that nectar, not color, is the primary attractant of prey to carnivorous pitcher plants in their native habitats. Prey capture (either all taxa summed or individual common taxa considered separately) was not associated with total red area or patterning on pitchers of living pitcher plants. We separated effects of nectar availability and coloration using painted "pseudopitchers", half of which were coated with sugar solution. Unsugared pseudopitchers captured virtually no prey, whereas pseudopitchers with sugar solution captured the same amount of prey as living pitchers. In contrast to a recent study that associated red coloration with prey capture but that lacked appropriate controls for nectar availability, we conclude that nectar, not color, is the primary means by which pitcher plants attract prey.

Role of Personal Connections in Shaping Decisions About Private Forest Use in Central Massachusetts 2008

We begin with a simple premise: Social and ecological systems are interconnected in complex ways. Forests are, perhaps, one of the most intriguing examples of this interconnectedness--particularly those in private ownerships. Forested landscapes are essential in maintaining human systems through the provision of multiple ecosystem services that span public (e.g., clean water, nutrient cycling) and private (e.g., fiber, maple syrup, home sites) goods. However, the majority of forestland in the Eastern United States is a mosaic of small landholdings (less than 20 ha) where property management is largely uncoordinated. On such landscapes, decentralized, ownership-centric decision-making defines the mix of ecosystem services provided and the landscape patterns present now and in the future. While somewhat effective for less spatially sensitive ecosystem services (e.g., fiber production), this ownership-centric approach is ill suited to spatially sensitive ones (e.g., water quality) and may, in some cases, be detrimental to them (e.g., habitat fragmentation). Improving the ecological and landscape sensitivity of private forest conservation and management is a major challenge facing researchers, practitioners, and policymakers in sustaining forest ecosystems. Central to unraveling this challenge is a fundamental understanding of how landowners simultaneously fit within their social and bio-physical landscapes. Despite their importance to broader forest sustainability, our collectively understanding of forest landowners has been primarily concerned with individual landowners and/or individual properties. For example, most research surrounding private forest landowners centers on primarily agent-based theories of behavior or decision-making (e.g., rational actor, theory of planned behavior). This perspective is useful in predicting and effecting behavior at broad scales, but lacks the specificity needed to address local landscape concerns and/or opportunities. Other studies

Role of Moose and Deer Browsing in Harvested Forests of Southern New England since 2008

In the past 20 years, moose have spread south from Vermont and New Hampshire and recolonized their pre-historical range limit in southern New England from which they had been extirpated almost 200 years earlier. Intensive moose browsing in the boreal forest has caused declines in forest density and shifts in species composition in some areas, generating considerable interest and concern among foresters, wildlife managers, and ecologists as to how moose along with white-tailed deer will impact forest development in this region. Harvard Forest in collaboration with researchers at the USGS Massachusetts Cooperative Research Unit has initiated a long-term study of the role of moose and deer in SNE forests using experimental exclosures. The design is a randomized block with 3 factors -- full exclosure, partial exclosure, and control plot. Full exclosures exclude both moose and deer but allow access to small mammals such as mice, squirrels, and rabbits. Partial exclosures have a 60cm opening around the bottom perimeter of the fence, which excludes moose but allows access to deer and other small and medium-sized animals. The design enables us to quantify forest composition and structure in areas (1) exposed to moose and deer browsing,(2) protected from moose and deer browsing, and (3) exposed to deer browsing but protected from moose browsing.

Tree Growth and Coarse Woody Debris in Regenerating Forests at Harvard Forest since 2008

This project is a field-based study to measure sequestration of atmospheric carbon dioxide in a regenerating New England forest. This study established long-term biometric plots suitable for measuring changes in carbon storage through time in three forest stands: an early-20th-century conifer plantation, a naturally regenerating former conifer plantation harvested in the 1990s, and a conifer plantation scheduled for harvest next winter. The first three years of this project determined the initial carbon budget of these forest stands, measured carbon fluxes into and out of these stands, and laid the groundwork for future investigations. Subsequent years will investigate larger-scale questions, such as how successional patterns affect carbon sequestration, and how these patterns change with stand age. The work also addresses how forestry practices influence carbon sequestration, and provide guidance for how forest management could enhance terrestrial carbon uptake in the future.