Martin Ritchie

• B.S. Forestry, M.S. Statistics, PhD Forest Biometrics
• Research Forester at US Forest Service

Background The capacity of forest fuel treatments to moderate the behavior and severity of subsequent wildfires depends on weather and fuel conditions at the time of burning. However, in-depth evaluations of how treatments perform are limited because encounters between wildfires and areas with extensive pre-fire data are rare. Here, we took advanta...

Restoring current ponderosa pine (Pinus ponderosa Dougl. Ex P. and C. Laws)-dominated forests (also known as “dry forests”) to spatially resilient stand structures requires an adequate understanding of the overstory spatial variation of forests least impacted by Euro-American settlers (also known as “reference conditions”) and how much contemporary...

Background The capacity of forest fuel treatments to limit the behavior and severity of subsequent wildfires depends on weather and fuel conditions at the time of burning. We compared the impacts of five fuel treatments—including two thin-only, a thin-burn, a burn-only, and a control—on fire severity using a 1200 hectare randomized and replicated e...

Hardwoods resprouting after wildfire or cutting develop as multistemmed clumps that gradually self-thin over time. There is increasing interest in thinning of sprouting species to accelerate the formation of tree characteristics important to indigenous cultural practices and wildlife such as large-diameter stems, large branches, broad crowns, and a...

Quaking aspen (Populus tremuloides) is a valued, minor component on northeastern California landscapes. It provides a wide range of ecosystem services and has been in decline throughout the region for the last century. This decline may be explained partially by the lack of fire on the landscape due to heavier fire suppression, as aspen benefit from...

This study was conducted to improve estimation of concomitant variables for implementation of a stand density management diagram (SDMD) for ponderosa pine (Pinus ponderosa Laws.) in northern California and Oregon. In traditional SDMD, isolines for variables such as stand volume are presented in such a way that uncertainty with estimation is not ava...

The theory and practice of prescription design and multiple considerations for precommercial thinning (PCT) in California forests.

The Goosenest Adaptive Management Area was established in 1994 on the Klamath National Forest with the intent of evaluating late-successional forest characteristics. A large-scale experiment was established in the late 1990s to evaluate a range of management strategies. Treatments include combinations of mechanical thinning and prescribed fire. Obs...

Forest inventories based on field surveys can provide quantitative measures of regeneration such as density and stocking proportion. Understanding regeneration dynamics is a key element that supports silvicultural decision-making processes in sustainable forest management. The objectives of this study were to: 1) describe historical regeneration in...

Quaking aspen (Populus tremuloides) is a valued, minor component on western landscapes. It provides a wide range of ecosystem services and has been in decline throughout the arid west for the last century. This decline may be explained partially by the lack of fire on the landscape as aspen benefit from fire that eliminates conifer competition and...

Natural regeneration cannot be effectively evaluated by tree density because of spatial heterogeneity typically observed. A proper interpretation of natural regeneration will consider some evaluation of area stocked. However, stocking estimates for natural regeneration are plot-size-dependent. Stocking at the 1-milacre scale is not generally compar...

Controlling competing vegetation is vital for early plantation establishment and growth. Aboveground biomass (AGB) response to manual grubbing release from shrub competition was compared with no release control in a twelve-year-old ponderosa pine (Pinus ponderosa Lawson & C. Lawson) plantation established after a wildfire in northeastern California...

Stand density affects not only structure and growth, but also the health of forests and, subsequently, the functions of forest ecosystems. Here, we integrated dendrochronology and repeated inventories for ponderosa pine research plots to determine whether long-term growth and mortality responded to climate trends and how varying stand density influ...

Accurate estimates of growth and structural changes are key for forest management tasks such as determination of optimal rotation times, optimal rotation times, site indices and for identifying areas experiencing difficulties to regenerate. Estimation of structural changes, especially for biomass, is also key to quantify greenhouse gas (GHG) emissi...

Group-selection silviculture has many beneficial attributes and has increased in application over the past 30 years. One difficulty with group-selection implementation is the designation of group openings within a stand to achieve a variety of complex management goals. This study presents a new method for utilizing geospatial census stem map data d...

Spreadsheet adaptation of Oliver and Powers Yield Tables

OP-Yield is a Microsoft Excelâ„¢ spreadsheet with 14 specified user inputs to derive custom yield estimates using the original Oliver and Powers (1978) functions as the foundation. It presents yields for ponderosa pine (Pinus ponderosa Lawson & C. Lawson) plantations in northern California. The basic model forms for dominant- and subdominant-height...

Selected allometric equations and fitting strategies were evaluated for their predictive abilities for estimating above ground biomass for seven species of shrubs common to northeastern California. Size classes for woody biomass were categorized as 1-h fuels (0.1–0.6 cm), 10-h fuels (0.6–2.5 cm), 100-h fuels (2.5–7.6 cm), and 1000-h fuels (greater...

Historically, oak woodlands in western North America were maintained by frequent fire that killed competing conifers. Today, these woodlands are often in decline as competition from conifers intensifies. Among oak species affected is the ecologically important California black oak (Quercus kelloggii Newberry). Within its range, large high-severity...

Timber is frequently salvage-logged following high-severity stand-replacing wildfire, but the practice is controversial. One concern is that compound disturbances could result in more deleterious impacts than either disturbance individually, with mechanical operations having the potential to set back recovering native species and increase invasion...

An experiment designed to evaluate the treatment effects of salvaging merchantable fire-killed trees on surface fuels and regeneration was established after a wildfire in northeastern California. The study was then monitored for 10 years. Surface fuel accumulations were rapid, corresponding with a high rate of snag decay and subsequent breakage or...

The US Department of Agriculture (USDA) Forest Service Blacks Mountain Experimental Forest is a 4,000 ha, pine-dominated tract in northeastern California, in the Lassen National Forest. Between 1934 and 1960, research at Blacks Mountain focused on various methods of harvest and bark beetle activity. These studies demonstrated the effectiveness of h...

The Blacks Mountain Experimental Research Project created two distinct overstory structural classes (high-structural diversity [HiD]; low-structural diversity [LoD]) across 12 stands and subsequently burned half of each stand. We analyzed stand-level growth 10 years after treatment and then modeled individual tree growth to forecast stand-level gro...

Many western USA fire regimes are typified by mixed-severity fire, which compounds the variability inherent to natural regeneration densities in associated forests. Tree regeneration data are often discrete and nonnegative; accordingly, we fit a series of Poisson and negative binomial variation models to conifer seedling counts across four distinct...

The US Department of Agriculture (USDA) Forest Service Blacks Mountain Experimental Forest is a 4,000 ha, pine-dominated tract in northeastern California, in the Lassen National Forest. Between 1934 and 1960, research at Blacks Mountain focused on various methods of harvest and bark beetle activity. These studies demonstrated the effectiveness of h...

Forest understory communities are important components in forest ecosystems providing wildlife habitat and influencing nutrient cycling, fuel loadings, fire behavior and tree species composition over time. One of the most widely utilized understory component metrics is understory vegetation cover, often used as a measure of vegetation abundance. To...

We periodically measured overstory ponderosa pine (Pinus ponderosa) growth and understory cover and abundance in a long-term study on the west slope of the Sierra Nevada, California, USA. The study was established in 1969 in a 20-year-old plantation, thinned to basal areas of 9, 16, 23, 30, and 37 m(2) ha(-1) and rethinned three times. The objectiv...

CONIFERS is a model for young stand growth developed by personnel at the USFS Pacific Southwest Research Station in Redding, California. Although originally developed with a graph-ical user interface (GUI), currently only the dynamic linked library (dll) and an R package are supported and updated. The current version of the software includes four v...

Forest managers need accurate biomass equations to plan thinning for fuel reduction or energy production. Estimates of carbon sequestration also rely upon such equations. The current allometric equations for ponderosa pine (Pinus ponderosa) commonly employed for California forests were developed elsewhere, and are often applied without consideratio...

We analyzed 45 years of data collected from three ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) levels-of-growing-stock installations in Oregon (OR) and northern California (CA), USA, to determine the effect of stand density regimes on stand productivity and mortality. We found that periodic annual increment (PAI) of diameter, b...

We analyzed 45 years of data collected from three ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) levels-of-growing-stock installations in Oregon (OR) and northern California (CA), USA, to determine the effect of stand density regimes on stand productivity and mortality. We found that periodic annual increment (PAI) of diameter, b...

Large scale, high-severity fires are increasing in the western United States. Despite this trend, there have been few studies investigating post-fire tree regeneration. We established a study in the footprint of the 2000 Storrie Fire, a 23,000 ha wildfire that occurred in northern California, USA. We used a stratified sampling design to quantify po...

In a study of post-fire logging effects over an 8 year period at Blacks Mountain Experimental Forest, salvage logging was conducted at varying levels of intensity after a 2002 wildfire event. In a designed experiment, harvest prescriptions with snag retention levels ranging from 0% to 100% in 15 experimental units were installed. Observations of st...

Site index, estimated as a function of dominant-tree height and age, is often used as an expression of site quality. This expression is assumed to be effectively independent of stand density. Observation of dominant height at two different ponderosa pine levels-of-growing-stock studies revealed that top height stability with respect to stand densit...

principle of multiple use management of the Nation’s forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the national forests and national grasslands, it strives—as directed by Congress—to provide increasingly grea...

Many U.S. forests, especially those with historically short-interval, low- to moderate-severity fire regimes, are too dense and have excessive quantities of fuels. Widespread treatments are needed to restore ecological integrity and reduce the high risk of destructive, uncharacteristically severe fires in these forests. Among possible treatments, h...

With increasing interest in fuels treatments to address the high risk of severe fires in the western United States, there is an attendant need to quantify the effectiveness of such treatments. In addition to the immediate effect of reducing levels of combustible material and the attendant impact on fire intensity, resource managers also need to qua...

We evaluated the stability of a complex regression model developed to predict the annual height growth of young Douglas-fir. This model is highly nonlinear and is fit in an iterative manner for annual growth coefficients from data with multiple periodic remeasurement intervals. The traditional methods for such a sensitivity analysis either involve...

The purpose of this article was to determine whether natural regeneration or planted seedlings should be used in group-selection openings. The answer depends on the survival and growth rate of both types of seedlings, and that could depend on the size of the openings and the effect of trees on their edge. In this side-by-side study, the natural pin...

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 solic...

This work presents the results from the initial model development of a simulator to predict vegetation dynamics in young plantations growing in a Mediterranean environment. The simulator can predict growth dynamics for coniferous crop trees as well as competing hardwoods and shrubs. Model specification included conifer, shrub, and hardwood competit...

Ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) stands with late-seral features are found infrequently, owing to past management activities throughout western North America. Thus, management objectives often focus on maintaining existing late-seral stands. Observations over a 65 year period of stands with no past history of harvest showed...

A common, but largely untested, strategy for maintaining forest biodiversity is to enhance stand structural complexity. A silvicultural experiment was implemented from 1996 to 1998 at Blacks Mountain Experimental Forest, California, to test the efficacy of two levels of structural diversity (high versus low) and two levels of prescribed underburnin...

A large-scale interior ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) study was conducted at the Blacks Mountain Experimental Forest in northeastern California. The primary purpose of the study was to determine the influence of structural diversity on the dynamics of interior pine forests at the landscape scale. High structural diversity...

The ecological research project of interior ponderosa pine forests at the Blacks Mountain Experimental Forest in northeastern California was initiated by an interdisciplin-ary team of scientists in the early 1990s. The objectives of this study were to determine the effects of stand structure, and prescribed fire on vegetation growth, resilience, an...

A wildfire at Blacks Mountain Experimental Forest provided the opportunity to observe fire severity at the point of transition between treated and untreated stands. At several locations in the forest, the wildfire burned from a dense stand of largely pole-size trees, into an area that had been recently treated with combinations of thinning and pres...

Six white fir trials were established during the last half-century to develop guidelines for managing the existing natural stands across northeastern California. We analyzed data collected from these trials at about 5-year intervals since their installation. Because these trials were independent of each other, the design and treatments varied among...

This paper describes implementation and early results of a large-scale, interdisciplinary experiment in the Goosenest Adaptive Management Area in northeastern California. The study is designed to investigate development of late-successional forest attributes in second- growth ponderosa pine stands. The experiment has four treatments replicated five...

This paper describes the development of growth equations for competing vegetation in young conifer plantations, consistent with an individual-tree growth model architecture. Response variables were height increment, basal diameter increment, and change in crown width for a 2-year growth interval. The results for three common competing shrub and thr...

We evaluated the relationship between crown cover measured with a vertical sight tube and stand basal area per acre in treated (thinned, burned, and thinned and burned) and untreated interior ponderosa pine (Pinus ponderosa P. & C. Lawson) stands in northeastern California. Crown cover was significantly related to basal area at the plot level and s...

In September of 2002, a wildfire in the southern Cascade Range of northern California encountered several treatment plots of the large Blacks Mountain Interdisciplinary Ecological Research Project (BMIERP). The BMIERP was designed to study the responses to creating contrasting vegetation structures of wildlife (i .e., song birds and small mammals),...

Introduction The severity and extent of wildfires in recent years (e.g. have increased public awareness of a widespread fuels problem throughout much of the western United States. The 2002 and 2003 fire seasons appear to have served to accentuate the magnitude of the fuels problem in the minds of many. Yet, trends of increasing dead and live biomas...

The Goosenest Adaptive Management Area (AMA) was established on the Klamath National Forest in northern California in 1994. The AMA was created to encourage development and testing of management strategies so as to improve the planning and implementation of management activities on the National Forest. A primary objective for the Goosenest AMA is t...

The Goosenest Adaptive Management Area (AMA) was established on the Klamath National Forest in northern California in 1994. The AMA was created to encourage development and testing of management strategies so as to improve the planning and implementation of management activities on the National Forest. A primary objective for the Goosenest AMA is t...

Three solutions are presented for estimating stems per acre when trees are tallied by diameter class with horizontal point sampling. The first solution is based on the arithmetic mean of the diameter-class limits. The second is based on the geometric mean of the diameter-class limits and is unbiased for uniform within-class diameter distributions....

Growth and yield simulators may be characterized with regard to the aggregation structure employed. Individual-tree simulators are an example of a passive aggregation approach. Whole-stand models represent an active aggregation structure. Of particular interest is the disaggregative modeling approach, which employs elements of both individual-tree...

Growth and yield simulators may be characterized with regard to the aggregation structure employed. Individual-tree simulators are an example of a passive aggregation approach. Whole-stand models represent an active aggregation structure. Of particular interest is the disaggregative modeling approach, which employs elements of both individual-tree...

The efficiency of six disaggregative methods and two individual-tree methods was evaluated in terms of their ability to predict 5-year basal area increment for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in western Oregon. Models were developed for predicting gross stand basal-area increment and individual-tree diameter increment. In...

The efficiency of six disaggregative methods and two individual-tree methods was evaluated in terms of their ability to predict 5-year basal area increment for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in western Oregon. Models were developed for predicting gross stand basal-area increment and individual-tree diameter increment. In...

The effects oi small openirgs in iorest stands ha\ interested sih iculruri\I\ rLrd ecologists for r-e.rrs. lnlerest generally has centefed on the \egerrlion in rhe opeting!. not on rhrt immediatel)- oursjde of them. Quandtative i brmalion on the growt| of tfees adjacent rir group setectioi opcnings. altlnNgh oiien mentiLrn.d jn forestr) tertbooks a...

The equations presented predict crown area for 13 species of trees and shrubs which may be found growing in competition with commercial conifers during early stages of stand development. The equations express crown area as a function of basal area and height. Parameters were estimated for each species individually using weighted nonlinear least squ...

Exploring the long-term sustainability of managed forest ecosystem using the field experimental approach, while recognised as being a research priority, is not a straightforward task. This is true of many long-term forestry trials despite the use of the scientific method, designed experiments, and the advantages of modern equipment. Managers and re...

SYSTUM-1 is an individual-tree/distance-independent simulator developed for use in young plantations in California and southern Oregon. The program was developed to run under the DOS operating system and requires DOS 3.0 or higher running on an 8086 or higher processor. The simulator is designed to provide a link with existing PC-based simulators (...

Equations for predicting individual-tree height growth per 5-year period are presented for Douglas-fir, white fir, grand fir, ponderosa pine, sugar pine, and incense-cedar growing in the mixed-conifer zone of southwest Oregon. The data used to develop the equations came from 3,648 trees sampled from 391 stands in the study area. Parameters were est...

Five model forms were evaluated for their ability to predict height growth rate of individual Douglas-firs (Pseudotsuga menziesii [Mirb.] Franco) growing in even or uneven-aged stands of southwest Oregon. Three models had been previously used for Douglas-fir; the fourth was a simple modification of one of these, and the fifth was developed in this...

Equations are presented for predicting height to crown base (or bole ratio) for fourteen species of trees common to the mixed-conifer zone of southwest Oregon. Nonlinear regression was used to fit a weighted logistic function for each specie. The independent variables include height, crown competition factor in larger trees, stand basal ares, site...

Using a sample of 866 Douglas-firs, a predictive model is presented which expresses 5-year height growth as a nonlinear function of potential height growth, crown ratio and height of the subject tree divided by dominant stand height. The adjusted coefficient of multiple determination () of this model exceeded 0.70, which was superior to four altern...

Equations are presented for predicting basal area increment for individual Douglas-fir and grand fir trees in the east-central Coast Range of Oregon. Final parameter estimates were obtained using weighted nonlinear regression analysis of a simple exponential model. Two equations are presented for each species: one has site index, and the other has...

Typescript (photocopy). Thesis (M.S.)--Oregon State University, 1985. Includes bibliographical references (leaves 73-77).

Regression Equations are presented for predicting diameter inside bark at breast height and squared diameter inside bark for Douglas-fir with diameter and squared diameter outside bark as the independent variables. Three types of equations were fitted to data collected from 724 Douglas-fir felled in western Oregon. A nonlinear model with a weight o...