Don C. Bragg

The impacts of increasing drought on forest dynamics, structure, and biodiversity in the United States

We synthesize insights from current understanding of drought impacts at stand-to-biogeographic scales, including management options, and we identify challenges to be addressed with new research. Large stand-level shifts underway in western forests already are showing the importance of interactions involving drought, insects, and fire. Diebacks, changes in composition and structure, and shifting range limits are widely observed. In the eastern US, the effects of increasing drought are becoming better understood at the level of individual trees, but this knowledge cannot yet be confidently translated to predictions of changing structure and diversity of forest stands. While eastern forests have not experienced the types of changes seen in western forests in recent decades, they too are vulnerable to drought and could experience significant changes with increased severity, frequency, or duration in drought. Throughout the continental United States, the combination of projected large climate-induced shifts in suitable habitat from modeling studies and limited potential for the rapid migration of tree populations suggests that changing tree and forest biogeography could substantially lag habitat shifts already underway. Forest management practices can partially ameliorate drought impacts through reductions in stand density, selection of drought-tolerant species and genotypes, artificial regeneration, and the development of multistructured stands. However, silvicultural treatments also could exacerbate drought impacts unless implemented with careful attention to site and stand characteristics. Gaps in our understanding should motivate new research on the effects of interactions involving climate and other species at the stand scale and how interactions and multiple responses are represented in models. This assessment indicates that, without a stronger empirical basis for drought impacts at the stand scale, more complex models may provide limited guidance.

Impacts and management implications of ice storms on forests in the southern United States

This review explores the ecological and silvicultural impacts of ice storms on forests in the southern United States. Different environmental factors like weather conditions, topography, vegetation, stand density, and management practices influence the degree of glaze damage a particular forest may experience. Additionally, the frequent contradictions in the relationships between these factors and the resulting damage suggests a complexity that makes each ice storm unique and difficult to predict. We recommend a series of silvicultural responses to ice storms, including density management, planting species selection, postevent evaluation, salvage, stand rehabilitation, and long-term monitoring of forest health. Published by Elsevier B.V.

Reference conditions for old-growth pine forests in the Upper West Gulf Coastal Plain

DON C. BKAGG (U.S. Department of Agriculture, Forest Service, Southern Research Station). Reference conditions for old-growth pine forests in the Upper West Gulf Coastal Plain. J. Torrcy. Bot. Sot. 129: 261-288. 2002.-Ecosystem restoration has become an important component of forest management, especially on public lands. Howeber, determination of manageable reference conditions has lagged behind the interest. This paper oresents a case studv from Dine-dominated forests in the Upper West Gulf Coastal Plain NJWGCP), with special . . emphasis on southern Arkansas. Decades of forest management, fire exclusion, exotic species invasion, and other ecological changes have converted the small remnants of mature shortleaf (Pirius echirm/cl Mill.) and loblolly pine (Pinus trteda L.) stands into ineffectual models for restoring presettlement-like conditions. However, sufficient information can be gathered from available references to more reliably describe the boundaries of the desired reference environment. Early explorer accounts, maps, survey records, historical trade and technical publications, and modern scientific journals were consulted to reconstruct presettlement (pre1900) forest conditions for pine-dominated landscapes of the UWGCP On average, virgin UWGCP pine forests had considerably more shortleaf pine (especially in the uplands) than contemporary natural stands, with relatively low basal area and standing volume concentrated in large trees. Presettlement pine timber also had less uniform structural and spatial patterns than modern examples of mature pine. Assuming most of the critical processes ilre still present, it appears possible to recreate the compositional and structural attributes of virgin pine forests.

Modeling large woody debris recruitment for small streams of the Central Rocky Mountains.

As our understanding of the importance of large woody debris (LWD) evolves, planning for its production in riparian forest management is becoming more widely recognized. This report details the development of a model (CWD, version 1.4) that predicts LWD inputs, including descriptions of the field sampling used to parameterize parts of the model, the theoretical and practical underpinnings of the model’s structure, and a case study of CWD’s application to a stream in Wyoming’s Bridger-Teton National Forest.

Natural Presettlement Features of the Ashley County, Arkansas Area

Abstract The General Land Office (GLO) survey records of the Ashley County, Arkansas, area were analyzed for natural attributes including forest composition and structure, prairie communities and aquatic and geomorphological features. Almost 13,000 witness trees from at least 23 families were extracted from the surveys. Most (68% of the total) witness trees were black oak (Quercus velutina), pine (Pinus spp.), post oak (Q. stellata), white oak (Q. alba), hickory (Carya spp.) and sweetgum (Liquidambar styraciflua), with 60% of the taxa having fewer than 20 individuals and 26% represented by a single tree. Witness trees were usually moderate sized with very few small or large individuals noted. The distribution of presettlement grasslands, bottomland forests and upland mixed pine/hardwood forests was approximately mapped across the study area. Catastrophic disturbances mentioned in the GLO records included windthrow, floods, fire, timber harvest and earthquakes. Even during this early period, European settlers were altering the Ashley County landscape with trails, homes, farms, cotton gins and small-scale land clearing. Other notable ecological features in these survey records included large woody debris, wetlands, unique terrain conditions and wild game.

Composition, structure, and dynamics of a pine-hardwood old-growth remnant in southern Arkansas

different overstory tree species, with loblolly pine (Pinus taeda L.), shortleaf pine (Pinus echinata Mill.), and white oak (Quercus alba L.) comprising the majority of stand basal area. Hardwoods are most numerous, dominated by shade-tolerant species such as red maple (Acer rubrum L.), flowering dogwood (Cornus florida L.), blackgum (Nyssa sylvatica L.), and winged elm (Ulmus alata Michx.), especially in the subcanopy and understory. Large pines, oaks, and sweetgum are scattered throughout the stand, with some individuals exceeding 100 cm DBH and 45 m tall. Overstory trees rarely proved sound enough to age, but some stumps, logs, and increment cores suggest that the dominant canopy pines are 100 to 150 years old, with the largest individuals exceeding 200 years. Pines contributed the greatest amount of coarse woody debris. The average volume of dead wood was noticeably less than other examples of old-growth upland forest in the eastern United States, attributable largely to salvage. Increased windthrow and the salvage of dead and dying pines have become the primary perturbations of the LWDE Without large-scale disturbance like catastrophic fire or logging, shadeintolerant pines, oaks, and sweetgum (Liquidambar styraciflua L.) will decline in prominence, to be replaced by more shade-tolerant species.

Structural Attributes of Two Old-Growth Cross Timbers Stands in Western Arkansas

Abstract Comprised of largely non-commercial, xeric, oak-dominated forests, the Cross Timbers in Arkansas have been heavily altered over the last two centuries, and thus only scattered parcels of old-growth timber remain. We inventoried and mapped two such stands on Fort Chaffee Military Training Center in Sebastian County, Arkansas. The west-facing Christmas Knob site is located on an isolated hill, while the southerly-facing Big Creek Narrows site is on a long, narrow rocky outcrop called Devils Backbone Ridge. These sites occupied rocky, south- to southwest-facing sandstone-dominated slopes, with primarily post oak (Quercus stellata) and blackjack oak (Q. marilandica) overstories. Post oak dominated the largest size classes at both sites. Increment cores indicated that some post oaks exceeded 200 y of age, and tree-ring dating also confirmed an uneven-aged structure to these stands. Both locations had irregular reverse-J shaped diameter distributions, with gaps, deficiencies, and excesses in larger size classes that often typify old-growth stands. On average, the post oaks at the Big Creek Narrows site were taller, larger in girth, and younger than those on the Christmas Knob site, suggestive of a better quality site at Big Creek. The application of neighborhood density functions on stem maps of both sites found random patterns in tree locations. These stands are very similar in their structure to old-growth examples in other parts of the Cross Timbers ecoregion.

Experimental forests and ranges : 100 years of research success stories

In 2008, Forest Service Research and Development celebrated the Centennial Anniversary of these Experimental Forests and Ranges. This publication celebrates the many scientists who over the course of decades conducted the long-term studies that began and are continuing to shed light on important natural resource issues. Story suggestions were solicited from the Experimental Forest and Range Working Group and were selected to demonstrate the array of research issues being addressed on these living laboratories. Gathering a wealth of information from her interviews with scientists, Gail Wells proceeded to write these “…wonderful success stories from 100 years of research.” Studies established decades ago on many of these sites are still going strong. Experimental forests and ranges provide a valuable, long-term stream of information about the land and its resources. Over the years, researchers have built an impressive body of science to support good land management and further understanding of natural processes. Their research sheds light on many important questions. These experimental forests serve as living laboratories that help us connect the future to the past.

Potential Contributions of Figured Wood to the Practice of Sustainable Forestry

Abstract The birdseye grain of sugar maple (Acer saccharum Marsh.) can showcase the potential of figured wood in sustainable forestry. This poorly understood but valuable grain abnormality commands such a premium that its presence alone can influence timber management. Good forestry and logging practices can help assure that quality birdseye maple logs are not relegated to low-value uses. Birdseye specialty markets have also developed, creating opportunities for pieces of small or irregular dimensions. Even though few have the same promise as birdseye maple, figured grains are found in virtually every tree species, thus increasing the potential for other high-value niche markets. However, the relative rarity and slow formation of figured grains threaten their sustainability, until more research on their genetics, propagation, and silviculture becomes available.

Biomass Estimates of Small Diameter Planted and Natural-Origin Loblolly Pines Show Major Departures from the National Biomass Estimator Equations

Agriculture and Food Research Initiative Competitive Grant from the USDA National Institute of Food and Agriculture [2009-35103-05356]; Southern Research Station of the USDA Forest Service; Arkansas Forest Resources Center