Kevin O'Hara

University of California, Berkeley | UCB · Department of Environmental Science, Policy, and Management

This book presents the latest scientific and management information on multiaged silviculture, an emerging strategy for managing forestry systems worldwide. Over recent decades, forest science and management have tended to emphasize plantation silviculture. Whilst this clearly meets our wood production needs, many of the world's forests need to be...

Silviculture is a means to meet objectives ranging from timber production to wildlife habitat to naturalness. A common global trend in forestry is development of new silvicultural approaches as alternatives to plantation forestry that bear names that include the words ‘nature’, ‘ecological’ or some other positive expression regarding their intent o...

Coast redwood (Sequoia sempervirens (Lamb. ex. D. Don) Endl.) is unique among conifer species because of its longevity, the great sizes of individual trees, and its propensity to reproduce through sprouts. Timber harvesting in the native redwood range along the coast of the western United States has necessitated restoration aimed to promote old for...

Silvicultural practices are generally developed to meet societal objectives given the constraints of the site. This simple premise is a foundation of modern silviculture. However, silviculture may vary for other reasons related to cultural factors. This paper reviews the differences in silviculture in the twelve countries that comprise southeastern...

Open access models for academic publishing offer an alternative to traditional subscription-based journals. In the open access model, the author generally retains the copyright and the published articles are available free on the internet. Publication costs are either borne by the author as article processing charges, or are free for some journals...

Data capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research - from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring prog...

The mixed-conifer forests in California’s Sierra Nevada include species from several genera (Pinus, Abies, Pseudotsuga, Calocedrus and Sequoiadendron). These forests have complex disturbance regimes dominated by low to moderate severity fire that often resulted in patchy spatial patterns and multiaged stands. Leaf area index (LAI) describes the tot...

Research Highlights: Bark thickness (BT) in coastal redwood (Sequoia sempervirens (D.Don) Endl.) varies in accordance with tree size, crown ratio, position within the canopy, height along the tree stem, genetic identity and latitude. However, current BT predictive equations do not account for such variability, leading to inaccurate BT estimations....

Silviculture was used to direct the development of young redwood stands toward old forest stand structures. Two variable-density thinning treatments and an unthinned control treatment were monitored for 10 years following treatment in young coast redwood (Sequoia sempervirens) stands in northern California, USA. The intent of these treatments was f...

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research sp...

Quercus wutaishansea populations on the Loess Plateau are currently becoming more dominant in natural secondary forests, whereas Pinus tabulaeformis is declining. In the present paper, the diameter class (instead of age) was used to classify the different growth stages as juvenile, subadult, or adult, and the univariate function g(r) was used to an...

Determining the optimal rotation period was a crucial component of forest sustainable management strategies, especially under climate change. This paper had two objectives: (1) to determine the economic benefits and optimal rotation periods for timber production when coupled to carbon sequestration, as predicted by time series prediction models for...

The Forest Stewardship Council (FSC) aims to promote environmentally responsible forest management globally. However, quantifiable evidence of effects of FSC on forest management practices is lacking. FSC has been present in the Russian forestry arena for over 20 years. In this case study, we compare ecological indicators of forest management in FS...

For millennia, natural disturbance regimes, including anthropogenic fire and hunting practices, have led to forest regeneration patterns that created a diversity of forest lands across the USA. But dramatic changes in climates, invasive species, and human population, and land use have created novel disturbance regimes that are causing challenges to...

We analyzed variations in three tree properties: tissue density, carbon fraction, and carbon density within bole tissues of nine Californian conifer species. Model performance for all three tree properties was significantly improved with the addition of covariates related to crown characteristics and position within the tree. This suggests that bio...

Shifting disturbance regimes can have cascading effects on many ecosystems processes. This is particularly true when the scale of the disturbance no longer matches the regeneration strategy of the dominant vegetation. In the yellow pine and mixed conifer forests of California, over a century of fire exclusion and the warming climate are increasing...

El raleo de densidad variable (RDB) es una forma de redireccionar la trayectoria de desarrollo de rodales hacia una estructura de rodal más heterogénea. En rodales de secuoyas costeras (Sequoia sempervirens) en California, se ha utilizado el RDB para dirigir el desarrollo de rodales jóvenes hacia estructuras de bosques adultos. Los bosques adultos...

The practice of silviculture is continually evolving in response to a multitude of social, economic, and ecological factors. In 1986, the Journal of Forestry published a series of papers that reflected on changes in silviculture in the United States from the 1950s to 1980s and predicted how silviculture might develop in the next 30 years. We revisi...

Coast redwood (Sequoia sempervirens (D. Don) Endl.) height growth and basal area growth are sensitive to variations in site quality. Site factors known to be correlated with redwood stand growth and yield include topographic variables such as position on slope, exposure, and the composite variable: topographic relative moisture index. Species compo...

Straw mulch is commonly used for post-fire erosion control in severely burned areas but this practice can introduce non-native species, even when certified weed-free straw is used. Rice straw has recently been promoted as an alternative to wheat under the hypothesis that non-native species that are able to grow in a rice field are unlikely to estab...

Carbon fractions of tree tissues are a key component of forest carbon mass estimation. Several methods have been used to measure carbon fractions, yet no comprehensive comparison between methods has been performed. We found significant differences between carbon fractions derived from four sample preparation methods: oven-drying, vacuum desiccation...

We review the use of leaf area metrics (LAM) for assessing and managing dryland forests. We propose a framework integrating individual tree to whole-ecosystem metrics representing a variety of forest features and review theory, empirical evidence and knowledge gaps. Four basic concepts underlie the LAM framework: (1) Max-LAI – an ecosystem can be c...

We studied biophysical (biotic and abiotic) factors correlating with dominant height and basal area (BA) development within 110 ha of evergreen mixed conifer forest dominated by coast redwood (Sequoia sempervirens (D. Don) Endl.) in north coastal California. Various descriptors of species composition, topography, soil properties and moisture, light...

We used six metrics of size and growth variation (standard deviation (SD), coefficient of variation (CV), skewness coefficient (·S·), Gini coefficient (·G·), Lorenz asymmetry coefficient (LAC), and growth dominance coefficient (GD)) to describe changes in two long-term ponderosa pine (·Pinus ponderosa· Douglas ex P. Lawson & C. Lawson) initial spac...

Six precommercial thinning treatments and two types of control treatments were established in 9- to 11-year-old, even-aged coast redwood (Sequoia sempervirens (D Don) Endl.) forests in coastal California to study the impact of thinning on stand and individual tree level volume growth. Species composition was 74% redwood and 23% coast Douglas-fir (P...

Prediction of projected tree leaf area using allometric relationships with sapwood cross-sectional area is common in tree- and stand-level production studies. Measuring sapwood is difficult and often requires destructive sampling. This study tested multiple leaf area prediction models across seven diverse conifer species in the Sierra Nevada of Cal...

Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among speci...

Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among speci...

Understanding how plants are constructed; i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals; is essential for modeling plant growth, estimating carbon stocks, and mapping energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting sp...

Identifying clonal lineages in asexually reproducing plants using microsatellite markers is complicated by the possibility of nonidentical genotypes from the same clonal lineage due to somatic mutations, null alleles, and scoring errors. We developed and tested a clonal identification protocol that is robust to these issues for the asexually reprod...

Tree mortality is a vital component of forest management in the context of prescribed fires: however, few studies have examined the effect of prefire tree health on postfire mortality. This is especially relevant for sugar pine (Pinus lambertiana Douglas), a species experiencing population declines due to a suite of anthropogenic factors. Using dat...

We studied spatial autocorrelation in productivity across 110 ha of coast redwood (Sequoia sempervirens) forest in north coastal California. Height growth of dominant redwood trees, basal area (BA) growth, and volume growth were assessed in a grid of 234 permanent sample plots. Semi-variance analysis indicated that productivity was spatially autoco...

Pervasive forest mortality is expected to increase in future decades as a result of increasing temperatures. Climate-induced forest dieback can have consequences on ecosystem services, potentially mediated by changes in forest structure and understory community composition that emerge in response to tree death. Although many dieback events around t...

A 22-year-old spacing study was used to examine development of leaf area index (LAI) from different initial spacings in giant sequoia (Sequoiadendron giganteum (Lindl.) Buchholz). Fifteen trees ages 3‐36 years were dissected to develop leaf area predictions from sapwood cross-sectional area. Tree leaf area and LAI were estimated from three plots pe...

Background/Question/Methods Pervasive forest mortality events due to climate change have been observed on all six plant covered continents in recent years, and such forest diebacks are expected to increase in the coming decades as a result of increasing temperatures. Yellow-cedar (Callitropsis nootkatensis) has been dying off since the late 1800s...

Ponderosa pine (Pinus ponderosa P. & C. Lawson) is highly suitable for management using multiaged systems. This suitability is primarily the result of a frequent, low severity disturbance regime, but also because it naturally occurs at low densities and has a long history of management to promote multiple age classes. Several different stocking con...

Estimating site productivity in irregular structures is complicated by variations in stand density, structure, composition in mixed stands, and suppression experienced by subordinate trees. Our objective was to develop an alternate to site index (SI) and demonstrate its application in models of individual-tree and stand growth. We analyzed coast re...

Land managers in the Pacific Northwest have reported a need for updated scientific information on the ecology and management of mixed-conifer forests east of the Cascade Range in Oregon and Washington. Of particular concern are the moist mixed-conifer forests, which have become drought-stressed and vulnerable to high-severity fire after decades of...

The stand concept is in question because of a trend toward more complex structures and broad-scale management of many forests. The stand was traditionally a uniform operational unit designed to make management efficient. Stand-level objectives on some ownerships have recently shifted toward increasing within-stand variability through the use of var...

Forest management faces an uncertain future with changing climates and disturbance regimes. Multi-aged forest management systems represent a promising approach for increasing resistance and resilience, thereby limiting major disruptions to timber production and other ecosystem services. Multi-aged stands inherently have greater resistance and resil...

Giant sequoia were planted at various densities and tracked for 22 years to quantify the effect of growing space on diameter, height, stem volume, branch diameter, and branch density. Beginning after just 4 years and continuing through year 22, both stem diameter and height growth were highly sensitive to initial planting density (expressed in this...

In dry western Unites States forests where past resource management has altered the ecological role of fire and stand characteristics alike, mechanical thinning and prescribed burning are commonly applied in wildfire hazard abatement. The reduced surface fuel loads and stand structures resulting from fuels modifications are temporary, yet few studi...

The relation between the growth efficiency of individual trees and stands is critical for scaling up tree-level effects to stand-level phenomena. In this paper, we introduce a new measure of space occupancy - the area exploitation index (AEI), computed as the ratio between the leaf area and the area potentially available (APA) - which has the abili...

Variable-density thinning (VDT) is an emerging thinning method to enhance stand structural heterogeneity by deliberately thinning at different intensities within a stand. Subsequent stand development forms a more varied structure than is common in many even-aged forest stands. A primary difficulty with VDT treatments is systematically attaining het...

Undergraduate forestry programs in the United States have been accredited by the Society of American Foresters since 1935. Over the subsequent 75 years, the list of accredited undergraduate programs has grown, but several of the original programs have recently dropped their forestry programs or their accreditation. When forestry programs were first...

Carbon sequestration and wood volume production will be major objectives of future forestry projects. Optimization of these two objectives will require a better understanding of how management regimes affect stand average wood density and carbon fraction. Two contrasting coast redwood (Sequoia sempervirens) sites were chosen for analysis of volume...

The Scotia Plantation was established in 1982 on the large alluvial flat south of Scotia and adjacent to the Eel River. Seedlings, from local "woods run" seed sources, were planted on a 3.1 x 3.1 m (10 x 10 ft) grid. Site quality was very high, with site index averaging greater than 45 m (50 yr base). In 1997, the area was divided into blocks and a...

Sudden oak death, an emerging disease caused by the exotic pathogen Phytophthora ramorum, is impacting coast redwood (Sequoia sempervirens) forests throughout coastal California. The most severely affected species, tanoak (Notholithocarpus densiflorus), is currently widespread and abundant in the redwood ecosystem, but diseased areas have begun to...

Carbon sequestration is an emerging forest management objective within California and around the world. With the passage of the California's Global Warming Solutions Act (AB32) our need to understand the dynamics of carbon sequestration and to accurately measure carbon storage is essential to insure successful implementation of carbon credit projec...

A large-scale pruning study was established in the winter of 1999 to2000 at seven different sites on Green Diamond Resource Company forestlands in Humboldt County. The objective of this study was to determine the effects of pruning on increment, epicormic sprouting, stem taper, heartwood formation, and bear damage on these young trees. Pruning trea...

Variable-density thinning (VDT) is an emerging thinning method that attempts to enhance stand structural heterogeneity by deliberately thinning at different intensities throughout a stand. VDT may create stands with dense areas, open areas, and other areas that may be intermediate in density. Subsequent stand development forms a more varied structu...

Sampling with different plot types and sizes was simulated using tree location maps and data collected in three even-aged coast redwood (Sequoia sempervirens) stands selected to represent uniform, random, and clumped spatial patterns of tree locations. Fixed-radius circular plots, belt transects, and variable-radius plots were installed by simulati...

Questions How is sudden oak death disease progression affected by forest type? Which specific factors influence mortality rates and patterns? How do these trends vary across spatial scales? Location Point Reyes National Seashore, California, USA. Methods Sudden oak death, caused by the exotic pathogen Phytophthora ramorum, is affecting forests th...

Sudden oak death is dramatically altering forests throughout coastal California, but little is known about the communities that are assembling in affected areas. This emerging disease, caused by the exotic pathogen (S. Werres, A.W.A.M. de Cock), has had especially severe effects on tanoak ( (Hook. & Arn.) Manos, Cannon & S.H. Oh), a broadleaf everg...

Fire is a major component of the disturbance regime and a critical determinant of competitive outcomes in many ecosystems. In forests dominated by coast redwood (Sequoia sempervirens), fire was frequent and ubiquitous prior to European settlement, but fires have been exceedingly small and rare over the last 70–80 years because of aggressive fire pr...

Two rival silvicultural systems for promoting multiaged ponderosa pine stands emerged in the 1930s and 1940s. Maturity selection was developed to move the vast ponderosa pine (Pinus ponderosa) acreage in eastern Oregon and Washington into regulation to limit bark beetle losses. In the Southwest, improvement selection was designed to improve residua...

Tanoak (Notholithocarpus densiflorus syn. Lithocarpus densiflorus) is one of the most widespread and abundant associates of coast redwood (Sequoia sempervirens), but little is known about the structural relationships between these two species. Knowledge of such relationships is essential for a thorough understanding of the impacts of sudden oak dea...

Background/Question/Methods Sudden oak death, an emerging disease caused by the exotic pathogen Phytophthora ramorum, is impacting forests and woodlands throughout coastal California. Tanoak (Lithocarpus densiflorus), the most abundant broadleaf tree in the conifer-dominated forests of the infested area, is the most severely affected species; sever...

To accelerate development of old forest features in coast redwood, two thinning treatments and an unthinned control were compared in three treatment areas in north coastal California. One thinning treatment was designed to restore old forest densities of 125 trees/ha and the other 250 trees/ha representing a one-step and partial treatments to the d...

Post-thinning stump sprout response was assessed in a coast redwood [Sequoia sempervirens (D. Don) Endl.] stand from 5 to 9 years after five treatments were initiated. Nine years after treatment, leaf area index (LAI) ranged from 5.9 to 14.1 and the percent above canopy light (PACL) ranged from 0.8 to 3.9. Sprout responses included rapid self-thinn...

Prescribed fire is an important tool for fuel reduction, the control of competing vegetation, and forest restoration. The accumulated fuels associated with historical fire exclusion can cause undesirably high tree mortality rates following prescribed fires and wildfires. This is especially true for sugar pine (Pinus lambertiana Douglas), which is a...

Sugar pine trees from nine stands in two California study areas were assessed to determine the effects of pruning on the incidence and growth of white pine blister rust. Lower limbs up to 8 feet high were removed on alternate trees. Six years following treatment, the number of infections in pruned trees was reduced compared to unpruned trees at one...

Coast redwood (Sequoia sempervirens), a western North American conifer of ancient lineage, has a paradoxical combination of late-successional characteristics and strong adaptations to disturbance. Despite its shade tolerance and heavy dominance of the canopy on many sites, redwood saplings are uncommon in upland old-growth stands. Information neede...

Multiaged silviculture is highly variable across North America but a commonality is the ties to the negative exponential diameter distribution to guide stocking control. These methods have evolved in several regions to include alternative stand structures and new stocking control tools are being developed. A trend in these new developments is integ...

• Young coast redwood (Sequoia sempervirens (D. Don.) Endl.) trees were pruned to various heights to examine the effect of pruning severity on epicormic sprouting. Seven separate stands were used with as many as six treatments per stand in coastal Humboldt County, California, USA. • Epicormic sprout development was affected by pruning severity but...

Sugar pine (Pinus lambertiana) is a major component of the mixed-conifer forests found in the Sierra Nevada Mountains of California, USA. In the past several decades, sugar pine mortality has increased due to an introduced pathogen, white pine blister rust (caused by Cronartium ribicola). This study described stand development patterns in the mixed...