Land use change and forest management effects on soil carbon stocks in the Northeast U.S.

BACKGROUND: In most regions and ecosystems, soils are the largest terrestrial carbon pool. Their potential vulnerability to climate and land use change, management, and other drivers, along with soils' ability to mitigate climate change through carbon sequestration, makes them important to carbon balance and management. To date, most studies of soil carbon management have been based at either large or site-specific scales, resulting in either broad generalizations or narrow conclusions, respectively. Advancing the science and practice of soil carbon management requires scientific progress at intermediate scales. Here, we conducted the fifth in a series of ecoregional assessments of the effects of land use change and forest management on soil carbon stocks, this time addressing the Northeast U.S. We used synthesis approaches including (1) meta-analysis of published literature, (2) soil survey and (3) national forest inventory databases to examine overall effects and underlying drivers of deforestation, reforestation, and forest harvesting on soil carbon stocks. The three complementary data sources allowed us to quantify direction, magnitude, and uncertainty in trends. RESULTS: Our meta-analysis findings revealed regionally consistent declines in soil carbon stocks due to deforestation, whether for agriculture or urban development. Conversely, reforestation led to significant increases in soil C stocks, with variation based on specific geographic factors. Forest harvesting showed no significant effect on soil carbon stocks, regardless of place-based or practice-specific factors. Observational soil survey and national forest inventory data generally supported meta-analytic harvest trends, and provided broader context by revealing the factors that act as baseline controls on soil carbon stocks in this ecoregion of carbon-dense soils. These factors include a range of soil physical, parent material, and topographic controls, with land use and climate factors also playing a role. CONCLUSIONS: Forest harvesting has limited potential to alter forest soil C stocks in either direction, in contrast to the significant changes driven by land use shifts. These findings underscore the importance of understanding soil C changes at intermediate scales, and the need for an all-lands approach to managing soil carbon for climate change mitigation in the Northeast U.S.

Stronger fertilization effects on aboveground versus belowground plant properties across nine U.S. grasslands.

Increased nutrient inputs due to anthropogenic activity are expected to increase primary productivity across terrestrial ecosystems, but changes in allocation aboveground versus belowground with nutrient addition have different implications for soil carbon (C) storage. Thus, given that roots are major contributors to soil C storage, understanding belowground net primary productivity (BNPP) and biomass responses to changes in nutrient availability is essential to predicting carbon-climate feedbacks in the context of interacting global environmental changes. To address this knowledge gap, we tested whether a decade of nitrogen (N) and phosphorus (P) fertilization consistently influenced aboveground and belowground biomass and productivity at nine grassland sites spanning a wide range of climatic and edaphic conditions in the continental United States. Fertilization effects were strong aboveground, with both N and P addition stimulating aboveground biomass at nearly all sites (by 30% and 36%, respectively, on average). P addition consistently increased root production (by 15% on average), whereas other belowground responses to fertilization were more variable, ranging from positive to negative across sites. Site-specific responses to P were not predicted by the measured covariates. Atmospheric N deposition mediated the effect of N fertilization on root biomass and turnover. Specifically, atmospheric N deposition was positively correlated with root turnover rates, and this relationship was amplified with N addition. Nitrogen addition increased root biomass at sites with low N deposition but decreased it at sites with high N deposition. Overall, these results suggest that the effects of nutrient supply on belowground plant properties are context dependent, particularly with regard to background N supply rates, demonstrating that site conditions must be considered when predicting how grassland ecosystems will respond to increased nutrient loading from anthropogenic activity.

Hyphae move matter and microbes to mineral microsites: Integrating the hyphosphere into conceptual models of soil organic matter stabilization.

Associations between soil minerals and microbially derived organic matter (often referred to as mineral-associated organic matter or MAOM) form a large pool of slowly cycling carbon (C). The rhizosphere, soil immediately adjacent to roots, is thought to control the spatial extent of MAOM formation because it is the dominant entry point of new C inputs to soil. However, emphasis on the rhizosphere implicitly assumes that microbial redistribution of C into bulk (non-rhizosphere) soils is minimal. We question this assumption, arguing that because of extensive fungal exploration and rapid hyphal turnover, fungal redistribution of soil C from the rhizosphere to bulk soil minerals is common, and encourages MAOM formation. First, we summarize published estimates of fungal hyphal length density and turnover rates and demonstrate that fungal C inputs are high throughout the rhizosphere-bulk soil continuum. Second, because colonization of hyphal surfaces is a common dispersal mechanism for soil bacteria, we argue that hyphal exploration allows for the non-random colonization of mineral surfaces by hyphae-associated taxa. Third, these bacterial communities and their fungal hosts determine the chemical form of organic matter deposited on colonized mineral surfaces. Collectively, our analysis demonstrates that omission of the hyphosphere from conceptual models of soil C flow overlooks key mechanisms for MAOM formation in bulk soils. Moving forward, there is a clear need for spatially explicit, quantitative research characterizing the environmental drivers of hyphal exploration and hyphosphere community composition across systems, as these are important controls over the rate and organic chemistry of C deposited on minerals.

Soil carbon stocks in temperate grasslands differ strongly across sites but are insensitive to decade-long fertilization.

Enhancing soil carbon (C) storage has the potential to offset human-caused increases in atmospheric CO2 . Rising CO2 has occurred concurrently with increasing supply rates of biologically limiting nutrients such as nitrogen (N) and phosphorus (P). However, it is unclear how increased supplies of N and P will alter soil C sequestration, particularly in grasslands, which make up nearly a third of non-agricultural land worldwide. Here, we leverage a globally distributed nutrient addition experiment (the Nutrient Network) to examine how a decade of N and P fertilization (alone and in combination) influenced soil C and N stocks at nine grassland sites spanning the continental United States. We measured changes in bulk soil C and N stocks and in three soil C fractions (light and heavy particulate organic matter, and mineral-associated organic matter fractions). Nutrient amendment had variable effects on soil C and N pools that ranged from strongly positive to strongly negative, while soil C and N pool sizes varied by more than an order of magnitude across sites. Piecewise SEM clarified that small increases in plant C inputs with fertilization did not translate to greater soil C storage. Nevertheless, peak season aboveground plant biomass (but not root biomass or production) was strongly positively related to soil C storage at seven of the nine sites, and across all nine sites, soil C covaried with moisture index and soil mineralogy, regardless of fertilization. Overall, we show that site factors such as moisture index, plant productivity, soil texture, and mineralogy were key predictors of cross-site soil C, while nutrient amendment had weaker and site-specific effects on C sequestration. This suggests that prioritizing the protection of highly productive temperate grasslands is critical for reducing future greenhouse gas losses arising from land use change.

Root-derived inputs are major contributors to soil carbon in temperate forests, but vary by mycorrhizal type.

Roots promote the formation of slow-cycling soil carbon (C), yet we have a limited understanding of the magnitude and controls on this flux. We hypothesised arbuscular mycorrhizal (AM)- and ectomycorrhizal (ECM)-associated trees would exhibit differences in root-derived C accumulation in the soil, and that much of this C would be transferred into mineral-associated pools. We installed δ13 C-enriched ingrowth cores across mycorrhizal gradients in six Eastern U.S. forests (n = 54 plots). Overall, root-derived C was 54% greater in AM versus ECM-dominated plots. This resulted in nearly twice as much root-derived C in putatively slow-cycling mineral-associated pools in AM compared to ECM plots. Given that our estimates of root-derived inputs were often equal to or greater than leaf litter inputs, our results suggest that variation in root-derived soil C accumulation due to tree mycorrhizal dominance may be a key control of soil C dynamics in forests.

Leaf litter decay rates differ between mycorrhizal groups in temperate, but not tropical, forests.

Whereas the primary controls on litter decomposition are well established, we lack a framework for predicting interspecific differences in litter decay within and across ecosystems. Given previous research linking tree mycorrhizal association with carbon and nutrient dynamics, we hypothesized that the two dominant mycorrhizal groups in forests - arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi - differ in litter decomposition rates. We compiled leaf litter chemistry and decay data for AM- and ECM-associating angiosperms and gymnosperms (> 200 species) from temperate and tropical/subtropical, and investigated relationships among decay rates, mycorrhizal association, phylogeny and climate. In temperate forests, AM litters decayed faster than ECM litters, with litter nitrogen and phylogeny best explaining variation in litter decay. In sub/tropical forests, we found no significant difference in litter decay rate between mycorrhizal groups, and variation in decay rates was best explained by litter phosphorus. Our results suggest that knowledge of tree mycorrhizal association may improve predictions of species effects on ecosystem processes, particularly in temperate forests where AM and ECM species commonly co-occur, providing a predictive framework for linking litter quality, organic matter dynamics and nutrient acquisition in forests.

Utilization of primary care among college students with mental health disorders.

OBJECTIVE: Our goal was to assess whether integration of behavioral and medical services in college settings is associated with decreased use of primary care by patients with mental health diagnoses (MHDs). METHOD: The cohort consisted of 80,219 patients with at least 1 MHD in 21 universities. Two levels of service integration were defined: "standard"-universities with separate electronic health records (EHR) systems and minimal clinical collaboration between services, and "enhanced"-universities with shared EHR and collaborative patient care. Frequency, the total number of primary care visits, and complexity, the total visit length for primary care per unit time, were compared by using multilevel models. RESULTS: Nine schools met the criteria of enhanced clinical integration; a tenth school shifted to enhanced service during the study period. Student and patient demographics and clinical diagnoses were similar between the 2 categories. When controlling for variance in age, sex, and total time in school, patients with MHDs in standard systems had 15.72% (95% confidence interval [CI]: 10.77%-20.44%) more primary care visits and 22.88% (95% CI: 21.42%-24.38%) more time than patients in enhanced systems. CONCLUSIONS: Students with MHDs have significantly lower utilization of primary care services in integrated health care systems, but only a minority of institutions nationally have adopted this model of care. Although further research is needed to specifically assess differences in health outcomes and perceived suffering, it is possible that reduced primary care visits in enhanced integrative service settings with robust mental health support indicates overall reduction in perceived suffering for patients/clients. (PsycINFO Database Record

Pervasive and strong effects of plants on soil chemistry: a meta-analysis of individual plant 'Zinke' effects.

Plant species leave a chemical signature in the soils below them, generating fine-scale spatial variation that drives ecological processes. Since the publication of a seminal paper on plant-mediated soil heterogeneity by Paul Zinke in 1962, a robust literature has developed examining effects of individual plants on their local environments (individual plant effects). Here, we synthesize this work using meta-analysis to show that plant effects are strong and pervasive across ecosystems on six continents. Overall, soil properties beneath individual plants differ from those of neighbours by an average of 41%. Although the magnitudes of individual plant effects exhibit weak relationships with climate and latitude, they are significantly stronger in deserts and tundra than forests, and weaker in intensively managed ecosystems. The ubiquitous effects of plant individuals and species on local soil properties imply that individual plant effects have a role in plant-soil feedbacks, linking individual plants with biogeochemical processes at the ecosystem scale.

College Health Surveillance Network: Epidemiology and Health Care Utilization of College Students at US 4-Year Universities.

OBJECTIVE: This description of the College Health Surveillance Network (CHSN) includes methodology, demography, epidemiology, and health care utilization. PARTICIPANTS: Twenty-three universities representing approximately 730,000 enrolled students contributed data from January 1, 2011, through May 31, 2014. METHODS: Participating schools uploaded de-identified electronic health records from student health services monthly. RESULTS: During this study, just over 800,000 individuals used the health centers, comprising 4.17 million patient encounters. Sixty percent of visits included primary care, 13% mental health, 9% vaccination, and 31% other miscellaneous services. The 5 most common specific diagnostic categories (with annual rates per 100 enrolled students) were preventive (16); respiratory (12); skin, hair, and nails; infectious non-sexually transmitted infection (5 each); and mental health (4). Utilization and epidemiologic trends are identified among subpopulations of students. CONCLUSIONS: CHSN data establish trends in utilization and epidemiologic patterns by college students and the importance of primary and behavioral health care services on campuses.

Prevalence of substance misuse in new patients in an outpatient psychiatry clinic using a prescription monitoring program.

OBJECTIVE: To investigate the value of a prescription monitoring program in identifying prescription drug misuse among patients presenting to a resident physician outpatient psychiatry clinic at an academic medical center. METHOD: Participants were 314 new patients aged 18 years or older presenting to the clinic from October 2011 to June 2012. Resident physicians completed a data collection form for each participant using information from the patient interview and from the prescription monitoring program report. Prescription drug misuse was defined as having any 1 of the following 5 criteria in the prescription monitoring program report: (1) filled prescriptions for 2 or more controlled substances, (2) obtained prescriptions from 2 or more providers, (3) obtained early refills, (4) used 3 or more pharmacies, and (5) the prescription monitoring program report conflicted with the patient's report. RESULTS: At least 1 indicator of prescription drug misuse was found in 41.7% of patients. Over 69% of the patients that the residents believed were misusing prescription drugs actually met 1 of the criteria for prescription drug misuse. The prescription monitoring program report changed the management only 2.2% of the time. Patients with prior benzodiazepine use (χ(2) 1 = 17.68, P < .001), prior opioid use (χ(2) 1 = 19.98, P < .001), a personality disorder (χ(2) 1 = 7.22, P < .001), and chronic pain (χ(2) 1 = 14.31, P < .001) had a higher percentage of prescription drug misuse compared to patients without these factors. CONCLUSION: Using the prescription monitoring program to screen patients with prior benzodiazepine and opioid use, with a personality disorder, and/or with chronic pain may be useful in confirming the suspicion of prescription drug misuse identified at the initial evaluation.

Litter quality versus soil microbial community controls over decomposition: a quantitative analysis.

The possible effects of soil microbial community structure on organic matter decomposition rates have been widely acknowledged, but are poorly understood. Understanding these relationships is complicated by the fact that microbial community structure and function are likely to both affect and be affected by organic matter quality and chemistry, thus it is difficult to draw mechanistic conclusions from field studies. We conducted a reciprocal soil inoculum × litter transplant laboratory incubation experiment using samples collected from a set of sites that have similar climate and plant species composition but vary significantly in bacterial community structure and litter quality. The results showed that litter quality explained the majority of variation in decomposition rates under controlled laboratory conditions: over the course of the 162-day incubation, litter quality explained nearly two-thirds (64%) of variation in decomposition rates, and a smaller proportion (25%) was explained by variation in the inoculum type. In addition, the relative importance of inoculum type on soil respiration increased over the course of the experiment, and was significantly higher in microcosms with lower litter quality relative to those with higher quality litter. We also used molecular phylogenetics to examine the relationships between bacterial community composition and soil respiration in samples through time. Pyrosequencing revealed that bacterial community composition explained 32 % of the variation in respiration rates. However, equal portions (i.e., 16%) of the variation in bacterial community composition were explained by inoculum type and litter quality, reflecting the importance of both the meta-community and the environment in bacterial assembly. Taken together, these results indicate that the effects of changing microbial community composition on decomposition are likely to be smaller than the potential effects of climate change and/or litter quality changes in response to increasing atmospheric CO2 concentrations or atmospheric nutrient deposition.

Causes of Mortality Among American College Students: A Pilot Study.

This pilot study from self-selected institutions of higher education provides an estimate of the causes and rates of mortality among college students between the ages of 18 and 24 years old. One hundred fifty-seven 4-year colleges participated in an online survey of student deaths during one academic year. A total of 254 deaths were reported. The mortality rates (per 100,000) were as follows: total accidental injuries, 10.80; suicide, 6.17; cancer, 1.94; and homicide, 0.53. Within the accident and injury category, alcohol-related vehicular deaths (per 100,000) were 3.37 and alcohol-related nontraffic injuries were 1.49. Men had significantly higher rates of suicide (10.46) than women (2.34). Suggestions for future research and implications of these findings are discussed.

Alcohol-related vehicular death rates for college students in the Commonwealth of Virginia.

OBJECTIVE: Determine rate of college student alcohol-related vehicular traffic fatalities in Virginia during 2007. PARTICIPANTS: 17- to 24-year-old cohort [corrected] at colleges and universities in Virginia. METHODS: Institutions with membership in the American College Health Association were invited to participate in a survey. Data collected from institutional reports of student deaths due to vehicular accidents. RESULTS: Twenty-four institutions were invited to participate. Sixteen responded (response rate = 67%), comprising total enrollment of 117,100 for 17- to 24-year-olds (56% of total college population in state). Five traffic deaths were reported, representing 4.3 deaths per 100,000 students. Based on statewide statistics that estimate alcohol contributes to 38.9% of traffic deaths, rate of alcohol-related motor vehicle deaths is 1.7 deaths per 100,000 college students in Virginia, which is 89% lower than leading national estimates. CONCLUSIONS: These findings suggest that past estimates of alcohol-related vehicular deaths among college students are overstated.

Evaluation of a practice-based intervention to improve the management of pediatric asthma.

Pediatric asthma remains a significant burden upon patients, families, and the healthcare system. Despite the availability of evidence-based best practice asthma management guidelines for over a decade, published studies suggest that many primary care physicians do not follow them. This article describes the Provider Quality Improvement (PQI) intervention with six diverse community-based practices. A pediatrician and a nurse practitioner conducted the year-long intervention, which was part of a larger CDC-funded project, using problem-based learning within an academic detailing model. Process and outcome assessments included (1) pre- and post-intervention chart reviews to assess eight indicators of quality care, (2) post-intervention staff questionnaires to assess contact with the intervention team and awareness of practice changes, and (3) individual semi-structured interviews with physician and nurse champions in five of the six practices. The chart review indicated that all six practices met predefined performance improvement criteria for at least four of eight indicators of quality care, with two practices meeting improvement criteria for all eight indicators. The response rate for the staff questionnaires was high (72%) and generally consistent across practices, demonstrating high staff awareness of the intervention team, the practice "asthma champions," and changes in practice patterns. In the semi-structured interviews, several respondents attributed the intervention's acceptability and success to the expertise of the PQI team and expressed the belief that sustaining changes would be critically dependent on continued contact with the team. Despite significant limitations, this study demonstrated that interventions that are responsive to individual practice cultures can successfully change practice patterns.

A model-driven approach to qualitatively assessing the added value of community coalitions.

Community-based coalitions are commonly formed to plan and to carry out public health interventions. The literature includes evaluations of coalition structure, composition, and functioning; evaluations of community-level changes achieved through coalition activities; and the association between coalition characteristics and various indicators of success. Little information is available on the comparative advantage or "added value" of conducting public health interventions through coalitions as opposed to less structured collaborative mechanisms. This paper describes a qualitative, iterative process carried out with site representatives of the Controlling Asthma in American Cities Project (CAACP) to identify outcomes directly attributable to coalitions. The process yielded 2 complementary sets of results. The first were criteria that articulated and limited the concept of "added value of coalitions". The criteria included consensus definitions, an organizing figure, a logic model, and inclusion/exclusion criteria. The second set of results identified site-specific activities that met the definitional criteria and were, by agreement, examples of CAACP coalitions' added value. Beyond the specific findings relevant to the added value of coalitions in this project, the use of a social ecological model to identify the components of added value and the placement of those components within a logic model specific to coalitions should provide useful tools for those planning and assessing coalition-based projects.

Do "clicker" educational sessions enhance the effectiveness of a social norms marketing campaign?

OBJECTIVE: social norms campaigns are a cost-effective way to reduce high-risk drinking on college campuses. This study compares effectiveness of a "standard" social norms media (SNM) campaign for those with and without exposure to additional educational sessions using audience response technology ("clickers"). METHODS: American College Health Association's National College Health Assessment questions are used to evaluate actual and perceived use. Additional survey questions assess individual exposure to the interventions. RESULTS: the authors find "clicker" technology to be more effective than social norms poster media alone in reducing misperceptions of normative alcohol use for those students who attended clicker sessions. CONCLUSION: poster SNM campaigns may be most effective when supported by group "clicker" heath-related sessions.

The longitudinal pattern of alcohol-related injury in a college population: emergency department data compared to self-reported data.

BACKGROUND: Self-report survey is the most common method of obtaining information from college students on substance use and its consequences. However, the validity and reliability of self-report data, especially in relationship to harmful substance use, is frequently called into question. OBJECTIVES: To establish the convergent validity of self-reported alcohol-related injury data and data from a university-affiliated hospital Emergency Department (ED) across a seven year period. (2) To examine the trend lines for relative risk of alcohol-related injury. METHODS: Two existing data sets at a major public university are compared: records of 1,253 ED admissions for alcohol-related reasons and 13,518 survey responses. Convergent validity is evaluated with the Pearson correlation coefficients of the two data sets for 2001/2002 through 2007/2008. Longitudinal trends for each data set are evaluated by change in relative risk. RESULTS: Over the seven years, 51% of ED visits for alcohol-related reasons were due to injury, and 14% of survey respondents who drank alcohol reported alcohol-related injury. Both decreased significantly over the years: from 62% to 45% for ED reports and from 24% to 9% for self reports. ED visits for alcohol-related injury and self-reported alcohol-related injury are highly correlated: r = .67, 45% shared variance. CONCLUSIONS: The comparison establishes convergent validity for the self-report data and decreased rates of alcohol-related injury. SCIENTIFIC SIGNIFICANCE: These findings support the validity in college populations of self-report data about negative consequences associated with drinking alcohol.

Using a logic model to relate the strategic to the tactical in program planning and evaluation: an illustration based on social norms interventions.

Logic models are a ubiquitous tool for specifying the tactics--including implementation and evaluation--of interventions in the public health, health and social behaviors arenas. Similarly, social norms interventions are a common strategy, particularly in college settings, to address hazardous drinking and other dangerous or asocial behaviors. This paper illustrates an extension of logic models to include strategic as well as tactical components, using a specific example developed for social norms interventions. Placing the evaluation of projects within the context of this kind of logic model addresses issues related to the lack of a research design to evaluate effectiveness.

Legal ages for purchase and consumption of alcohol and heavy drinking among college students in Canada, Europe, and the United States.

Heavy drinking and associated negative consequences remain a serious problem among college students. In a secondary analysis of data from two published study, the authors examine the correlation between minimum legal age to purchase and/or consume alcohol and rates of heavy drinking among college students in 22 countries. The published studies use identical definitions of heavy drinking and similar methodologies. In the study of 20 European countries and the United States, there is a positive correlation between prevalence of heavy drinking and both minimum legal purchase age (r =.34) and minimum legal drinking age (r =.19); in the study of Canada and the United States, there is a perfect positive correlation (r = 1.0). Examination of this evidence does not support the conclusion that a lower minimum legal age for purchase and/or consumption of alcoholic beverages is a protective factor for decreasing heavy drinking among college students.