Chadwick Dearing Oliver

Forest development in North America following major disturbances

Abstract Large-scale, man-created or natural disturbances play a mjaor role in determining forest structure and species composition in many areas of North America and probably other temperate and tropical forests. Trees begin growth by a variety of mechanisms — each of which can respond to disturbances of a different severity. Studies suggest: a single group of species is not predestined to inhabit an area; forest physiognomic appearances assumed to imply all-aged succession often occur in single-age class stands; and recruitment of new stems into a forest often follows a disturbance rather than being a constant occurrence. After disturbances, forests develop through general physiognomic stages: “stand initiation”, “stem exclusion”, “understory reinitiation”, and “old growth”. Disturbance severity determines which species will dominate the forest afterward. The frequency of disturbances is also important in determining the general forest type over a large area, because species dominance and stand physiognomy change with time following disturbance.

Reconstruction of a Mixed‐Species Forest in Central New England

A 0.36—ha area in the Harvard Forest, Petersham, Massachusetts, was intensively analyzed to determine its history. Natural and man—caused disturbances of varying magnitudes occurred periodically in the central New England mixed—species stand. Evidence of two hurricanes and a fire prior to 1803 were found. Between 1803 and 1952, 14 natural or man—caused disturbances of various magnitudes occurred in the area. Large disturbances created new age classes, but small disturbances did not. Species arising together after large disturbances formed a distinct vertical stratification, with northern red oak (Quercus rubra L.) arising after several decades to the dominant canopy. Smaller disturbances to the overstory allowed understory trees such as black birch (Betula lenta L.), red maple (Acer rebrum L.), and eastern hemlock (Tsuga canadensis L. Carr.) to emerge to the dominant canopy. The composition of this forest was more the result of allogenic influences rather than autogenic development. See full-text article ...

DISTURBANCE HISTORY AND HISTORICAL STAND DYNAMICS OF A SEASONAL TROPICAL FOREST IN WESTERN THAILAND

Disturbances influence forest dynamics across a range of spatial and temporal scales. In tropical forests most studies have focused on disturbances occurring at small spatial and temporal scales (i.e., gap dynamics). This is primarily due to the difficulty of reconstructing long-term disturbance histories of forests in which most tree species lack annual growth rings. Consequently, the role of past disturbances in tropical forests is poorly understood. We used a combination of direct and indirect methods to reconstruct the his- torical disturbance regime and stand development patterns in mature and regenerating seasonal dry evergreen forest (SDEF) in the Huai Kha Khaeng Wildlife Sanctuary in western Thailand. Direct estimates of long-term establishment and growth patterns were obtained from 12 tree species that form annual growth rings as a consequence of the regions strong intra-annual rainfall seasonality. Indirect estimates of establishment patterns were obtained from analyses of stand structure and individual tree architecture and application of age- estimation models to 10 dominant canopy-tree species using demographic data from a large- scale, permanent forest-dynamics plot. The combination of direct and indirect methodologies revealed a complex disturbance history in the seasonal evergreen forest over the past 250 years. In the mid-1800s, 200-300 ha of forest were destroyed by a catastrophic disturbance, which led to the synchronous es- tablishment of many of the trees that presently dominate the forest canopy. Since then wide- spread disturbances of variable intensity have occurred at least three times (1910s, 1940s, and 1960s). These disturbances created discrete temporal pulses of establishment in small to large gaps in the forest matrix across several square kilometers. Background mortality and gap formation were evident in every decade since 1790, but these varied in intensity and frequency. The SDEF retains a distinct structural and floristic legacy from the catastrophic dis- turbance of the mid-1800s. The single-age cohort that established after the disturbance has developed a complex three-dimensional structure as a consequence of differences in in- terspecific growth patterns of the canopy-tree species and subsequent disturbances of mod- erate and low intensity. While no single methodological approach provided a complete picture of the disturbance history and stand development patterns of the seasonal evergreen forest, taken together they offered new insights into the long-term dynamics of a primary tropical forest. In particular, the study highlighted the role of disturbance at multiple spatial and temporal scales and varying intensities in determining the structure and composition of a complex, species-rich tropical forest and raises important questions about the role of rare, catastrophic events on tropical forest dynamics.

Carbon, Fossil Fuel, and Biodiversity Mitigation With Wood and Forests

Life-cycle analyses, energy analyses, and a range of utilization efficiencies were developed to determine the carbon dioxide (CO2) and fossil fuel (FF) saved by various solid wood products, wood energy, and unharvested forests. Some products proved very efficient in CO2 and FF savings, while others did not. Not considering forest regrowth after harvest or burning if not harvested, efficient products save much more CO2 than the standing forest; but wood used only for energy generally saves slightly less. Avoided emissions (using wood in place of steel and concrete) contributes the most to CO2 and FF savings compared to the product and wood energy contributions. Burning parts of the harvested logs that are not used for products creates an additional CO2 and FF savings. Using wood substitutes could save 14 to 31% of global CO2 emissions and 12 to 19% of global FF consumption by using 34 to 100% of the world’s sustainable wood growth. Maximizing forest CO2 sequestration may not be compatible with biodiversity. More CO2 can be sequestered synergistically in the products or wood energy and landscape together than in the unharvested landscape. Harvesting sustainably at an optimum stand age will sequester more carbon in the combined products, wood energy, and forest than harvesting sustainably at other ages.

Investing in forestry: opportunities and pitfalls of intensive plantations and other alternatives.

Abstract There is a surplus of wood growing in the world, despite generalizations about highly visible over-harvesting of some species and locations that suggests otherwise. Dealing with the oversupply by excluding natural forests from harvest and investing in intensive plantations is a risky strategy. Plantations require high financial investment, generally produce low quality wood, have a narrow “biological window” when they need harvesting, and put the entire investment at risk if this “window” is missed. Plantations could meet the worlds wood needs on about ten percent of the current forest area; however, if the nonplantation forests were harvested, these natural forests could produce less expensive, higher quality timber than plantations and ruin the plantation investment. Alternative strategies for timber investment include increasing global wood demand, targeting high quality wood niches, and managing forests for other uses in addition to wood. Intensive plantations may be profitable in a few situations or if global wood consumption increases dramatically. Also, intensive plantations can be useful for non-financial reasons.

Integrating Management Tools, Ecological Knowledge, and Silviculture

Forest management is becoming highly technical in both the natural and management sciences. Natural forests are in a constant state of disturbance and regrowth, rather than in a stable, steady state as previously thought. The contemporary social attitude is to reduce the extremes of natural and man-caused “boom and bust” cycles that affect animal and plant populations. Forest managers must apply specific measurable criteria at the landscape, stand structure, and operational levels to reduce the extremes and achieve desired social goals. Active management is needed to maintain the targeted array of stand structures and landscape patterns by doing specific silvicultural operations at specific times. Several discrete steps are involved: (1) Identify the measurable criteria to be targeted. (2) Determine existing stand structures and landscape patterns. (3) Develop alternative silvicultural systems suitable for each stand. (4) Project the changing stand structures and landscape patterns resulting from the alternative systems. (5) Analyze the alternative systems and select the best one for each stand. (6) Implement the operations. (7) Monitor the results to ensure that objectives are achieved. Fach step can be performed with varying degrees of detail, technical sophistication, and precision. The process is begun with incomplete knowledge, but adaptive management techniques can be used to make improvements along the way.

Decision rule-based approach to automatic tree crown detection and size classification

The goal of this study was to develop a decision rule heuristic that would incorporate theories of forest stand dynamics and crown competition into an automatic crown detection and crown size search algorithm. Specifically, we sought to develop new multi-dimensional template matching methods fused with knowledge-based decision rules that model spatial considerations for crown competition and develop multi-scale assessment criteria for appraisal of crown detection and crown size at the stand, local neighbourhood and individual crown levels. The decision rule approach to crown detection and crown size was tested on a mature mixed coniferous and deciduous forest typical of southern New England, USA. Multi-dimensional template matching was applied to a high resolution (30 cm per pixel side) colour infrared image of the study site. The decision rule heuristic developed for this study effectively reduced 2626 potential crown detections to 568 crowns, producing a 91% rate of crown detection when compared with the 516 field-measured crowns. The automatically derived crown size class distribution was shown to be statistically similar to the distribution of field crown size classes using the Kolomogorov–Smirnov statistic. Finally, a fuzzification of classification assignments to crown classes either one above or below actual crown size class resulted in an 80% match between individual field crowns and remotely sensed crowns within a 6 m spatial lag.

Integration of varying spatial, spectral and temporal high-resolution optical images for individual tree crown isolation

Automated methods for capturing geometric and spectral properties of individual tree crowns are becoming increasingly viable options for use in natural resource planning. Crown isolation techniques are needed that are capable of adapting to the changing availability and resolutions of remotely sensed data. Data integration, or the fusion of two distinct data entities, offers a methodological framework that can compensate for the shortcomings of individual datasets while enhancing their desirable features. This study sought to develop a method of data integration for high-resolution optical images of varying spatial and temporal resolutions to improve the automatic detection and delineation of individual tree crowns. A marker-controlled watershed segmentation (MCWS) algorithm was developed for a 30-cm-per-pixel-side airborne colour infrared (CIR) digital image of a leaf-on apple (Malus spp.) orchard. Three methods of obtaining the markers needed for the MCWS algorithm were tested: (1) manual marker selection, (2) template/correlation selection using the 30-cm CIR image, and (3) template/correlation selection using a 15-cm-per-pixel-side true (TRU) colour leaf-off aerial image. The effectiveness of integrating marker data of different temporal and spatial resolutions with the segmentation process of the CIR image scene was tested. A comparison of crown isolation results using markers derived within the segmented 30-cm CIR digital imagery with results from markers derived from the 15-cm TRU image scene indicated greater accuracies to detect and isolate tree crowns with data integration.

A Working Definition of Sustainable Forestry and Means of Achieving It at Different Spatial Scales

Summary Sustainable forestry can be a useful concept when it includes both spatial equity and the sustainable development concept of intergenerational equity. Using this definition and criteria such as those developed by the Montreal Process, each country can examine itself in a matrix to determine if it is overly protecting or exploiting its ecosystems according to the different criteria. Then, each country can examine the ecosystems within its country to determine if all are being equitably treated. For example, the United States appears sustainable when viewed as a whole; however, there are gross differences in ecosystem conditions within the country. Self-examination by each country of its contributions and voluntary actions to rectify its excesses and deficiencies will probably be more effective than a global policing system. Local, ground-specific actions can be taken to correct the imbalances within each ecosystem within a country. This paper illustrates that sustainable forestry can be considered and analyzed at different scales, and that even in countries where broad data sets indicate acceptable progress toward sustainable forestry, local data show the heterogeneous nature of this progress.

Functional Restoration of Social-Forestry Systems Across Spatial and Temporal Scales

Functional restoration of forests can be addressed as a combined socioeconomic and ecological complex system that involves both spatial and temporal hierarchies. Neither socioeconomic nor ecological systems are stable or have any central control or organization. Instead, they can change at different scales in many ways and be more or less vibrant—and more or less useful to people for different values. Restoration can direct these changes by determining what to control at each hierarchical level and what to allow to change on its own at a given time. Restoration at longer times and broader spatial scales involves much imprecision and uncertainty and is done with a few, careful controls. These controls are passed to each smaller spatial and temporal scale and other, more specific controls are added. Much has changed since most United States forest policies were instituted, so many of these policies need to be reevaluated. Rather than repeat policies and practices that worked in the past, we can look for new restoration solutions that are in line with our current understanding of complex systems. Many old forestry policies in the United States need changing to restore the forest functions in ways helpful to people.