Soil Chemical Response to Experimental Acidification Treatments

One of the conclusions reached during the Congressionally mandated National Acid Precipitation Program (NAPAP) was that, compared to ozone and other stress factors, the direct effects of acidic deposition on forest health and productivity were likely to be relatively minor. However, the report also concluded “the possibility of long-term (several decades) adverse effects on some soils appears realistic” (Barnard et al. 1990). Possible mechanisms for these long-term effects include: (1) accelerated leaching of base cations from soils and foliage, (2) increased mobilization of aluminum (Al) and other metals such as manganese (Mn), (3) inhibition of soil biological processes, including organic matter decomposition, and (4) increased bioavailability of nitrogen (N)

The Impact of Tree Species, Elevated Nitrogen Deposition, Stand Age, and Environmental Factors on Herbaceous Plant Communities in a Central Appalachian Hardwood Forest

Although the herb layer represents less than 1% of the biomass of temperate forests, this layer may contain up to 90% of the plant species in the forest and can contribute up to 20% of the foliar litter, thus playing an essential role in forest biodiversity and nutrient cycling. The objectives of this study were to investigate the differences in cover, species richness, Shannon-Wiener diversity, and evenness of herb layer plants a) under tree species associated with contrasting soil nitrogen levels and b) in watersheds that vary in nitrogen deposition, stand age, and watershed aspect at the Fernow Experimental Forest in West Virginia. In the watersheds evaluated, overstory tree species, N deposition level, stand age, and other environmental factors influenced herb layer characteristics. This study demonstrated 1) a sugar maple effect, i.e. sugar maple having a positive effect on understory cover, at intermediate levels of soil fertility in reference watersheds and in an N-fertilized watershed by improving the nutrient microenvironment for herb layer plants, 2) that long-term N enrichment can reduce ecosystem biodiversity by favoring nitrophilic species, and 3) that herb layer characteristics can be influenced by stand age, with more recent disturbance being reflected in higher herb layer abundance and diversity. This study justifies further examination of tree-herb layer interactions for a wider range of tree species, N-deposition levels, and stand ages in future studies in order to inform adaptive forest management in the light of climate change and other continuing anthropogenic influences

Climatic, edaphic, and biotic controls over storage and turnover of carbon in soils

Soil carbon, a major component of the global carbon inventory, has significant potential for change with changing climate and human land use. We applied the Century ecosystem model to a series of forest and grassland sites distributed globally to examine large-scale controls over soil carbon. Key site-specific parameters influencing soil carbon dynamics are soil texture and foliar lignin content; accordingly, we perturbed these variables at each site to establish a range of carbon concentrations and turnover times. We examined the simulated soil carbon stores, turnover times, and C:N ratios for correlations with patterns of independent variables. Results showed that soil carbon is related linearly to soil texture, increasing as clay content increases, that soil carbon stores and turnover time are related to mean annual temperature by negative exponential functions, and that heterotrophic respiration originates from recent detritus (∼50%), microbial turnover (∼30%), and soil organic matter (∼20%) with modest variations between forest and grassland ecosystems. The effect of changing temperature on soil organic carbon (SOC) estimated by Century is dSOC/dT= 183e−0.034T. Global extrapolation of this relationship leads to an estimated sensitivity of soil C storage to a temperature of −11.1 Pg° C−1, excluding extreme arid and organic soils. In Century, net primary production (NPP) and soil carbon are closely coupled through the N cycle, so that as temperatures increase, accelerated N release first results in fertilization responses, increasing C inputs. The Century-predicted effect of temperature on carbon storage is modified by as much as 100% by the N cycle feedback. Century-estimated soil C sensitivity (−11.1 Pg° C−1) is similar to losses predicted with a simple data-based calculation (−14.1 Pg° C−1). Inclusion of the N cycle is important for even first-order predictions of terrestrial carbon balance. If the NPP-SOC feedback is disrupted by land use or other disturbances, then SOC sensitivity can greatly exceed that estimated in our simulations. Century results further suggest that if climate change results in drying of organic soils (peats), soil carbon loss rates can be high

An investigation of Whip-poor-will activity, habitat use, and home range using radio telemetry within a managed landscape

The Whip-poor-will (Caprimulgus vociferus) is a nocturnal insectivore that is declining throughout many parts of its breeding range. Like several other Caprimulgid species, Whip-poor-wills have been suggested to utilize forested areas for nesting and open areas for foraging. The fact that Whip-poor-wills require resources that occur within distinctly different habitat types implies that their distribution and abundance may be influenced by the spatial association of required patches within a broader landscape. Within Weyerhaeuser forestlands in 1999 Wilson and Watts showed that Whip-poor-wills were detected within forest stands that were adjacent to plantations more frequently than forest stands adjacent to other forest stands. From a management perspective, this result suggests that targeted management should focus on a landscape scale and include the spatial and temporal orchestration of management activities. The objective of this study was to use radio telemetry to investigate the influence of landscape configuration and lunar illumination on home range size, activity patterns, and habitat use within a managed forest system. Twenty-seven Whip-poor-wills were fitted with radio transmitters and tracked in homogenous (forest stands bordered by other forest stands) and heterogeneous landscapes (forest stands bordered by open stands) of Weyerhaeuser’s J&W management tract. Home range size and activity patterns were shown to be similar between landscape types. The habitat composition of home ranges for Whip-poor-wills in heterogeneous landscapes was equally divided between forested and open stands. Overall, Whip-poorwills showed a strong tendency to use areas near forest openings such as open plantations and logging roads. The use of habitat openings present in both landscape types may be responsible, in part, for observed patterns of home range size and activity. Large habitat openings created by regeneration practices and extensive linear openings created by logging roads and row thinning appear to enhance landscape quality and provide Whip-poor-wills with foraging opportunities not likely present in non-managed forests

Fertilization and Tree Species Influence on Stable Aggregates in Forest Soil

Abstract: Background and objectives: aggregation and structure play key roles in the water-holding capacity and stability of soils and are important for the physical protection and storage of soil carbon (C). Forest soils are an important sink of ecosystem C, though the capacity to store C may be disrupted by the elevated atmospheric deposition of nitrogen (N) and sulfur (S) compounds by dispersion of soil aggregates via acidification or altered microbial activity. Furthermore, dominant tree species and the lability of litter they produce can influence aggregation processes. Materials and methods: we measured water-stable aggregate size distribution and aggregate-associated organic matter (OM) content in soils from two watersheds and beneath four hardwood species at the USDA Forest Service Fernow Experimental Forest in West Virginia, USA, where one watershed has received (NH4)2SO4 fertilizer since 1989 and one is a reference/control of similar stand age. Bulk soil OM, pH, and permanganate oxidizable carbon (POXC) were also measured. Research highlights: fertilized soil exhibited decreased macro-aggregate formation and a greater proportion of smaller micro-aggregates or unassociated clay minerals, particularly in the B-horizon. This shift in aggregation to soil more dominated by the smallest (\u3c53 μm) fraction is associated with both acidification (soil pH) and increased microbially processed C (POXC) in fertilized soil. Intra-aggregate OM was also depleted in the fertilized soil (52% less OM in the 53–2000 μm fractions), most strongly in subsurface B-horizon soil. We also document that tree species can influence soil aggregation, as soil beneath species with more labile litter contained more OM in the micro-aggregate size class (\u3c250 μm), especially in the fertilized watershed, while species with more recalcitrant litter promoted more OM in the macro- aggregate size classes (500–2000 μm) in the reference watershed. Conclusions: long-term fertilization, and likely historic atmospheric deposition, of forest soils has weakened macro-aggregation formation, with implications for soil stability, hydrology, and storage of belowground C

Productivity and carbon budgets of harvested Central Appalachian forests

Land conversion and industrial pollution are two of the most influential vehicles for anthropogenic perturbation of natural terrestrial processes and both have increased dramatically over the course of the last century. This research explores the role of Central Appalachian hardwood forests in the global carbon (C) balance during a century of regeneration with changing land use and atmospheric pollution. Most of the forests in this region were logged in the early 1900s. During the century the followed, nitrogen (N) deposition rates became especially high in parts of Central Appalachia where an increasing number of regenerated mature forests are now undergoing N saturation. I explored the effects of N saturation on processes that control productivity using a model that I modified to reflect conditions associated with Stage 2 of N saturation. I then applied the model to forests that have experienced different harvest histories during the last century of forest re-growth. I found that carefully planned harvests, such as diameter-limit cutting and single tree selection cutting, can stimulate ecosystem productivity by as much as 37%. To determine the regional contribution of mature forests to atmospheric C sinks, I assessed the spatial variability of foliar and soil N concentrations and applied the validated productivity model to sites across the state of West Virginia. Generally, I found that over the century of regeneration following harvest, forests in the Central Appalachian region sequestered an average of 4 to 5 Tg C yr -1. The modeled estimate of carbon storage is stimulated up to 20% by N saturation, a process that varies in intensity across the state and may be correlated with a transition in tree species composition. Loss of these forests would add about 300 Tg C to the atmosphere that would take another century to recover

Wooster Magazine: Winter 2016

The winter 2016 issue of the Wooster magazine focuses on building cultural community. William Longbrake ’65 introduces Sarah Bolton as the next Wooster President. Mark Wilson ’78 received a prestigious national award from the Council on Undergraduate Research. Distinguished Alumni include Lucius F. Ellsworth ’63, Elizabeth Eaton ’77, and George Davis ’64. This issue also took a behind-the-scenes look at leadership and critical thinking, highlighting: William McCulloch ’23, Max Lesko ’06, Justina Williams ’02, Jeff Beck ’92, Bruce Peterjohn ’74, Reverend Heidi Kugler ’94, Dave Unsworth ’81, and Art Pearce ’95. There is a section on International ambassadors (thriving international students); students included are Ruben Aguero Quinteros, Khue Minh Hoang, Lango Sichizya, and Nisa Usman. This issue also lists legacy students, promotes Dick Figge’s podcast, and shows David Morrow ’16 and Kelly Brethauer ’16 studying abroad in China for “A Wooster Moment.”https://openworks.wooster.edu/wooalumnimag_2011-present/1010/thumbnail.jp