Jennifer C. Jenkins

Turfgrass is a large fraction of land cover in urbanized areas around the world, but little information exists about basic ecological processes in lawns or the controls on these processes. Here, we characterize biomass carbon stocks and fluxes in tall fescue (Festuca arundinacea) appropriate for use on home lawns, managed with differing levels of i...

An inventory of land traditionally called “nonforest” and therefore not sampled by the Forest Inventory and Analysis (FIA) program was implemented by the FIA unit at the Northeastern Station in 1999 for five counties in Maryland. Biomass and biomass increment were estimated from the nonforest inventory data using techniques developed for applicatio...

Background/Question/Methods Large intra-annual changes in soil C pools have been observed under turfgrass lawns, and lawns have been observed to substantially increase soil C pools under certain conditions. In order to better understand these dynamics and determine any influence that lawn management might have on them, we conducted long-term (90+...

Historically, tree biomass at large scales has been estimated by applying dimensional analysis techniques and field measurements such as diameter at breast height (dbh) in allometric regression equations. Equations often have been developed using differing methods and applied only to certain species or isolated areas. We previously had compiled and...

Background/Question/Methods Turfgrass lawns represent a large fraction of urbanized land cover in the United States. Given high (3-5%) biomass N concentrations and net primary production that is comparable to other temperate ecosystems, it is likely that lawns will play a significant role in urban N dynamics. In order to gauge the magnitude of N...

Economic and political realities present challenges for implementing an aggressive climate change abatement program in the United States. A high-efficiency approach will be essential. In this synthesis, we compare carbon budgets and evaluate the carbon-mitigation potential for nine counties in the northeastern United States that represent a range o...

The rapid increase in residential land area in the United States has raised concern about water pollution associated with nitrogen fertilizers. Nitrate (NO3-) is the form of reactive N that is most susceptible to leaching and runoff; thus, a more thorough understanding of nitrification and NO3(-) availability is needed if we are to accurately predi...

Urban areas are growing in size and importance; however, we are only beginning to understand how the process of urbanization influences ecosystem dynamics. In particular, there have been few assessments of how the land-use history and age of residential soils influence carbon (C) and nitrogen (N) pools and fluxes, especially at depth. In this study...

Land conversion to developed use is associated with changes in land-based fluxes of carbon (C). Changes in vehicular transportation to and from the new development may also result in additional emissions from the burning of fossil fuels. National Land Cover Database (NLCD) and regional C sequestration rates from published literature were used to cr...

Background/Question/Methods Turfgrass represents a significant land cover type nationally, and is a dominant vegetation type in urbanized areas. In ecological analyses of urban areas, all turfgrass area is usually treated the same, despite evidence from sod production studies that management (i.e. fertilizing and watering) can alter turfgrass pro...

Hemlock woolly adelgid (Adelges tsugae Annand) is an invasive insect pest that is causing widespread mortality of eastern hemlock. However, some stands remain living more than a decade after infestation. To date, this has been attributed to site and climatic variables. This multi-tiered study examines the role foliar chemistry may play in A. tsugae...

It is increasingly important to understand how household characteristics influence lawn characteristics, as lawns play an important ecological role in human-dominated landscapes. This article investigates household and neighborhood socioeconomic characteristics as predictors of residential lawn-care expenditures and lawn greenness. The study area i...

Background/Question/Methods Residential lands cover a substantial portion of the land area in the United States, and this portion is increasing with time. Despite the importance of these areas, little is currently known about biogeochemical cycles in residential environments. In this study, we present results from a series of studies developed to...

Mountain pine beetle (MPB) outbreaks are important disturbances of forests in the western United States. Stand conditions influence the success of MPB attack through food availability, shelter, and effects on tree vigor and thus the ability of a tree to withstand MPB infestation. We estimated the contribution of stand structure to susceptibility to...

The emerging discipline of urban ecology is shifting focus from ecological processes embedded within cities to integrative studies of large urban areas as biophysical-social complexes. Yet this discipline lacks a theory. Results from the Baltimore Ecosystem Study, part of the Long Term Ecological Research Network, expose new assumptions and test ex...

In the western United States, forest ecosystems are subject to a variety of forcing mechanisms that drive dynamics, including climate change, land-use/land-cover change, atmospheric pollution, and disturbance. To understand the impacts of these stressors, it is crucial to develop assessments of forest properties to establish baselines, determine th...

In the western United States, bark beetle outbreaks affect millions of hectares of forests. These disturbances have multiple effects on ecosystems, including modifications to biogeochemical cycles, interactions with fire, and changes in land cover type and species composition. In recent years, extensive outbreaks have occurred in multiple forest ec...

W e use monitoring data routinely in our daily lives; we monitor the stock market, the weather, our blood pressure, and baseball statistics. But, does monitor-ing have a place in environmental science? Common crit-icisms of environmental monitoring are (1) that it is not really science, but merely a fishing expedition that diverts funds from "real"...

We use permanent-plot data from the USDA Forest Service's Forest Inventory and Analysis (FIA) program for an analysis of the effects of competition on tree growth along environmental gradients for the 14 most abundant tree species in forests of northern New England, USA. Our analysis estimates actual growth for each individual tree of a given speci...

Hemlock woolly adelgid (Adelges tsugae Armand) is an invasive insect pest that is causing widespread mortality of eastern hemlock. However, some stands remain living more than a decade after infestation. To date, this has been attributed to site and climatic variables. This multi-tiered study examines the role foliar chemistry may play in A. tsugae...

We combined integrated measurement and monitoring of vegetation, soil, and water with process and empirical models to estimate carbon stocks and dynamics of the Delaware River Basin. Agencies operating in the basin accepted the challenge of designing an integrated monitoring strategy by augmenting existing monitoring systems. Watersheds are logical...

Given the rate of suburban and exurban expansion in the US, conversion of land to residential use is likely to be an important contributor to regional ecosystem dynamics, but little is known about how suburban lands cycle C and N. In this study, we quantified turfgrass productivity, soil respiration, and soil C and N along a chronosequence of subur...

To assess what difference it might make to include spatially defined estimates of foliar nitrogen in the regional application of a forest ecosystem model (PnET-II), we composed model predictions of wood production from extensive ground-based forest inventory analysis data across the Mid-Atlantic region. Spatial variation in foliar N concentration w...

Forest sustainability has emerged as a crucial component of all current issues related to forest management. The seven Montreal Process Criteria are well accepted as categories of processes for evaluating forest management with respect to sustainability, and data collected by the Forest and Inventory Analysis (FIA) program of the United States Fore...

Estimates of national-scale forest carbon (C) stocks and fluxes are typically based on allometric regression equations developed using dimensional analysis techniques. However, the literature is inconsistent and incomplete with respect to large-scale forest C estimation. We compiled all available diameter-based allometric regression equations for e...

An inventory of land traditionally called "nonforest" and therefore not sampled by the Forest Inventory and Analysis (FIA) program was implemented by the FIA unit at the Northeastern Station in 1999 for five counties in Maryland. Biomass and biomass increment were estimated from the nonforest inventory data using techniques developed for applicatio...

Recent work has demonstrated the utility of USDA Forest Service Forest Inventory and Analysis (FIA) data in large-scale assessment of forest C cycling rates. These FIA-based estimates have also been used to provide valuable large-scale comparison data for ecosystem process model predictions. However, the inventory-based techniques were not designed...

There is general agreement that terrestrial systems in the Northern Hemisphere provide a significant sink for atmospheric CO2; however, estimates of the magnitude and distribution of this sink vary greatly. National forest inventories provide strong, measuretment-based constraints on the magnitude of net forest carbon uptake. We brought together fo...

1] Net primary productivity (NPP) in North America was computed for the years 1982 –1998 using the Carnegie-Ames-Stanford approach (CASA) carbon cycle model. CASA was driven by a new, corrected satellite record of the normalized difference vegetation index at 8-km spatial resolution. Regional trends in the 17-year NPP record varied substantially ac...

We used a new 17-year, high spatial resolution satellite record and a carbon cycle model to explore how changing net primary productivity (NPP) contributed to a proposed carbon (C) sink in North America. We found a small but significant increase in NPP, 0.03 Pg C yr-2 or 8% over 17 years, that could explain a substantial fraction of the C sink. The...

Climate data show significant increases in precipitation and humidity over the U.S. since 1900, yet the role of these hydro-climatic changes on the reported U.S. carbon sink is incompletely understood. Using a prognostic terrestrial ecosystem model, we simulated 1900–1993 continental U.S. carbon fluxes and found that increased growth by natural veg...

As interest grows in quantification of global carbon cycles, process model predictions of forest biomass and net primary production (NPP) are being developed at an accelerating rate. Such models can provide useful predictions at large scales, but it has been difficult to evaluate their performance. Using the network of plots comprising the comprehe...

Carbon accumulation in forests has been attributed to historical changes in land use and the enhancement of tree growth by CO2 fertilization, N deposition, and climate change. The relative contribution of land use and growth enhancement is estimated by using inventory data from five states spanning a latitudinal gradient in the eastern United State...

Net primary production (NPP) is defined as the rate at which carbon (C) is accumulated by autotrophs and is expressed as the difference between gross photosynthesis and autotrophic respiration. NPP is the resource providing for the growth and reproduction of all heterotrophs on Earth; as a result, it determines the planet’s carrying capacity (Vitou...

Because model predictions at continental and global scales are necessarily based on broad characterizations of vegetation, soils, and climate, estimates of carbon stocks and fluxes made by global terrestrial biosphere models may not be accurate for every region. At the regional scale, we suggest that attention can be focused more clearly on underst...

Mortality of dominant tree species caused by introduced pests and pathogens have been among the most pervasive and visible impacts of humans on eastern U.S. forests in the 20th century, yet little is known about the ecosystem-level consequences of these invasions. In this study we quantified the impacts of the introduced hemlock woolly adelgid (Ade...

Mortality of eastern hemlock (Tsuga canadensis (L.) Carriere) may be caused by a variety of agents, but hemlock trees of all sizes over a large geographic area are currently threatened by an outbreak of the hemlock woolly adelgid (HWA: Adelges tsugae Annand) in the eastern United States. In this paper, we review what is currently known about change...

Jennifer Jenkins and I were lead editors for a Dartmouth environmental studies class consisting of some 20 students. We researched and proposed the Dartmouth Organic Farm which eventually was founded and exists successfully today at https://www.sustainability.dartmouth.edu/organic-farm

The Delaware River Basin is in the coastal Mid-Atlantic region of the United States, covers 12,700 square miles of primarily forested land, and is home to 7.2 million people. Major watershed issues in the Delaware River Basin (DRB) are urbanization and forest fragmentation, varied abiotic and biotic stressors, diminished condition of forest soils a...

As interest grows in the role of fbrest growth in the carbon cycle, and as simulation models arc applied to predict future forest productivity at large spatial scales, the need for reliable and field-based data for evaluation of model estimates is clear. We created estimates of potential forest biomass and annual aboveground production for the Ches...

Urbanized land (i.e. "developed" land) covers 98.3 million acres in the United States, and the acreage in this category increased by 25% between 1982 and 1997, based on statistics from the 1997 USDA Natural Resource Inventory (this "developed" category includes "large urban built-up areas," "small urban built-up areas," and "rural transportation la...

We computed net primary production (NPP) using a biogeochemistry model (CASA) and a new satellite record of the normalized difference vegetation index (NDVI) spanning 1982 to 1998 in North America. We calculated a small but significant trend in the continental NPP. The largest trends in NPP occur in the managed forests of the southeastern United St...

Thousands of published equations purport to estimate biomass of individual trees. These equations are often based on very small samples, however, and can provide widely different estimates for trees of the same species. We addressed this issue in a previous study by devising 10 new equations that estimated total aboveground biomass for all species...

Measuring and monitoring forest productivity and carbon (C) is of growing concern for natural resource managers and policymakers. With the Delaware River Basin (DRB) as a pilot region, this subproject of the CEMRI sought to: Improve the ability of the ground-based Forest Inventory and Analysis (FIA) networks to more completely assess forest C stock...

At the longest temporal and largest spatial scales, we expect that soil and vegetation C stocks will be driven primarily by structural factors such as soil type and previous land use, and that this variation will be modulated by the age of the residential development. Conversely, we expect that short-term C fluxes will be determined primarily by th...

Includes bibliographical references. Thesis (Ph. D.)--University of New Hampshire, 1998.