bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Distance-Dependent and Distance-Independent Stand Growth Models—Is Perfect Aggregation Possible?
Authors: Kokkila Tero , Mäkelä Annikki , Franc Alain
Published: April 2024

Selecting a suitable level of accuracy in stand growth estimations is a question of practical importance. A detailed model is more complicated and demands more initial information from the user to produce reliable results. Despite being correct and more precise, it may well be that the more detailed results give no practical bonus value. The essential part of the estimations could also have been received with coarser means. We have used three levels of stand description accuracy. The first is a mean tree model (MTM), where all trees are assumed identical. The second is a distribution-based model (DBM), where size differences are allowed. Both versions are distance-independent and the spatial configuration of the stand is considered random. The third is a spatially explicit model (SEM), where all trees are described individually and their spatial locations are taken into account. The core dynamics in all models are kept the same, so a previous model is a straightforward aggregation of the latter one. The possibility of a perfect aggregation was examined both theoretically and by practical simulations. A process-based stand growth model ACROBAS was used to simulate the different levels of aggregation. The results demonstrate that under the Poisson assumption of stand spatial configuration there are hardly any differences among model aggregations. As mortality is not totally random in the SEM, the Poisson assumption does not hold through the whole simulation period. As the spatial configuration eventually tends toward regularity, the total growth in the stand is somewhat increased, which is evident in variables such as total stem volume and foliage mass. However, mean height and stocking density developments are almost identical in all models. This suggests that the mean height is “an almost perfect𠇍 aggregation variable.
Effect of Edge Trees on Harvester Positioning in Thinning
Authors: Ovaskainen Heikki , Uusitalo Jori , Sassi Tuomo
Published: April 2024

The objective of this study was to discover the influence of edge trees, the trees along the side of the strip road, on the positioning of modern single-grip harvester during the first commercial thinning. The results indicate that there is one main working location in the strip road where the harvester is positioned in a distance of two consecutive edge trees. This main location is determined by an edge tree located about 1.2 m behind the boom base. There are also other working locations within a certain distance but in most cases the harvester was positioned same way to the main location, which enables the least restricted boom operations in the boom working sector. Positioning the harvester according to the edge trees does not explain the considerable productivity differences among experienced harvester operators, but the awareness and significance of the edge trees give trainees a valuable basis for outlining and planning work in early stages of training. The present findings are also beneficial from the cutting damage and harvester configuration points of view.
Determinants of Forest Land Prices in Northern Minnesota: A Hedonic Pricing Approach
Authors: Snyder Stephanie A. , Kilgore Michael A. , Hudson Rachel , Donnay Jacob
Published: April 2024

A hedonic price model was developed to analyze the market for undeveloped forestland in northern Minnesota. The data included 387 forestland parcels purchased in 2001 or 2002. Information describing parcel physical characteristics, amenity features, merchantable timber volume, development trends, terms of financing, and several proximity, distance, and adjacency conditions were tested for their influence on forestland prices. The model's independent variables collectively explained approximately 50% of the variation in per hectare sale price. The method by which forestland sales were financed, road access and density, proximity to population centers, and presence of lake or river frontage had the largest positive influences on per hectare sale prices. Adjacency to public land had an unexpectedly large, negative influence on sale price. Importantly, a parcel's merchantable timber volume was not found to be a significant predictor of forestland sale price. In general, forestland markets were driven by three major influences: land development pressures, presence of or close proximity to a water body, and the use of contract for deed financing.
Compatible Estimators of the Components of Change for a Rotating Panel Forest Inventory Design
Authors: Roesch Francis A.
Published: April 2024

This article presents two approaches for estimating the components of forest change utilizing data from a rotating panel sample design. One approach uses a variant of the exponentially weighted moving average estimator and the other approach uses mixed estimation. Three general transition models were each combined with a single compatibility model for the mixed estimation approach. The four resulting estimation systems are compared and contrasted in a sample simulation study covering four simulated populations.
Effects of Timber Harvest on Suspended Sediment Loads in Mica Creek, Idaho
Authors: Karwan Diana L. , Gravelle John A. , Hubbart Jason A.
Published: April 2024

Long-standing concerns exist regarding timber harvest and subsequent sediment impacts on aquatic resources. Intensive studies on contemporary harvest practices remain rare, particularly in the interior Pacific Northwest. To investigate this, a network of seven automated stream monitoring flumes was installed in the Mica Creek Experimental Watershed, in northern Idaho. Beginning in 1991, water samples collected at each flume under both flow-based and stream-stage storm rise conditions have been analyzed for total suspended solids (TSS). This period of record encompasses a pretreatment time interval from 1991 to 1997, and two treatment time intervals: post-road from 1998 to 2001 and post-road/post-harvest from 2001 through 2004. Treated and control catchments were statistically compared using a paired watershed approach for immediate and recovery time intervals corresponding to each treatment activity, road construction and timber harvest. The impacts corresponding to road construction remain difficult to discern. The impacts corresponding to timber harvest differ based on harvest treatment and time period of analysis. Results suggest a correlation between increased sediment loads and clearcutting for a brief period following the harvest. No significant correlation was found in the partial cut watershed. Continued monitoring at these sites is planned to evaluate trends over subsequent years.
Headwater Riparian Microclimate Patterns under Alternative Forest Management Treatments
Authors: Rykken Jessica J. , Chan Samuel S. , Moldenke Andrew R.
Published: April 2024

Management of headwater streams and their riparian zones has included the implementation of forested riparian buffers, which are intended to protect ecological processes (such as microclimate) and biota, but the appropriate widths for these buffers have been widely debated. We measured the magnitude and extent of microclimatic gradients associated with headwater streams in mature unmanaged forests, and determined whether these patterns were maintained in clearcut harvested units with and without a 30 m-wide riparian buffer on each side of the stream. We measured air temperature, soil temperature, and relative humidity between 1 and 70 m from the stream in five replicate blocks of three treatments each in western Oregon. Results indicated the strongest stream effect on air temperature and relative humidity to be within 10 m of the stream in all management treatments at 3:00 pm, and gradients were evident to 20 m in the forested treatment. The clearcut was significantly hotter (air and soil) and drier than either the riparian buffer or the forest treatments at 3:00 pm. The riparian buffer and forest had similar microclimates at all distances from the stream, suggesting that the 30-m buffer adequately protected the riparian microclimatic gradient. We hypothesize that the strong stream effect on microclimate in the riparian zone serves a critical role in mitigating the influence of microclimatic “edge effects” associated with the forest-clearcut edge. Biota dependent on cool, humid microclimates provided by riparian zones will benefit from the implementation of riparian buffers in harvest units.
Effects of Clearcutting and Riparian Buffers on the Yield of Adult Aquatic Macroinvertebrates from Headwater Streams
Authors: Moldenke Andrew R. , Ver Linden Carolyn
Published: April 2024

We studied the emergence of Ephemeroptera, Plecoptera and Trichoptera (EPT) from headwater streams in Pacific Northwest conifer forests with emergence traps. We analyzed the effects of silvicultural management (clearcutting and riparian buffering) on insect species assemblages as a measure of the quantity of food resource available to insectivorous predators. Canopy removal increased the biomass and density of total EPTs and all feeding guilds except scrapers. Buffering does not change EPT yield from that of the mature forest (perhaps it decreases it), but the EPT community composition within the buffers becomes similar to that of adjacent clearcuts. Differences in community composition attributed to changes in elevation were more substantial than differences caused by silvicultural management. Forty percent of the species collected were restricted to one or another of the five sites.
Preliminary Study of the Effects of Headwater Riparian Reserves with Upslope Thinning on Stream Habitats and Amphibians in Western Oregon
Authors: Olson Deanna H. , Rugger Cynthia
Published: April 2024

We conducted a preliminary examination of the responses of stream amphibians and instream habitat conditions to alternative riparian buffer zones with forest thinning upslope. Pre and posttreatment surveys were carried out on 68 headwater stream reaches (including 23 unthinned reference reaches) at 11 sites in western Oregon. Streams were in managed conifer stands, 40 to 80 years old, where the thinning treatment reduced stands from 600 trees per hectare (tph) to 200 tph. Treatments consisted of four widths of riparian buffers approximately 6, 15, 70, and 145 m on each side of streams. Over three study years, 3,131 individuals of 13 species were detected. For the more common instream and bank species analyzed, capture rates persisted posttreatment with no negative treatment effect from thinning with any of the buffer widths. More animals were detected after thinning in treatment reaches compared to reference reaches for rough-skinned newts (Taricha granulosa Skilton) occurring on stream banks, and for instream coastal giant salamanders (Dicamptodon tenebrosus Baird and Girard). Treatment effects on instream habitat parameters were not detected. Interannual variation was evident for western red-backed salamanders (Plethodon vehiculum Cooper), and several habitat conditions including pool-riffle ratio, stream spatial intermittency, stream width, and down wood. Overall, riparian buffers with moderate upslope thinning (200 tph) seemed to have retained the aquatic vertebrate community along channels among sites in the first 2 years posttreatment; however, several limitations of the study reduce the inference of the findings, and these preliminary results are best interpreted as hypotheses for further investigation.
The Components of Change for an Annual Forest Inventory Design
Authors: Roesch Francis A.
Published: April 2024

The sample design of the USDA Forest Service's Forest Inventory and Analysis Program (FIA) with respect to a three-dimensional population (forest area × time) of tree attributes is formally defined and evaluated. The definitions for both the traditional components of growth, as presented by Meyer (1953, Forest Mensuration), and a discrete analog to the time invariant redefinition of the components of change given by Eriksson (1995, Forest Sci. 41(4):796–822), are compared and contrasted. Special problems in the application of the traditional definitions due to the continuous and overlapping temporal intervals featured in the sample design are explored. This exploration supports a contention that the traditional definitions are at a theoretical disadvantage because they are not based purely on the population(s) of interest, while the redefinitions dubbed the components of change by Eriksson (1995) were based solely on population attributes. The temporally discrete analog to the Eriksson definitions are used in this article to define the three-dimensional populations in terms of a set of mutually exclusive component matrices that can be summed to represent the entire population, independently of the sample design.
Interactive Effects of Soil Temperature and [CO2] on Morphological and Biomass Traits in Seedlings of Four Boreal Tree Species
Authors: Zhang Shouren , Dang Qing-Lai
Published: April 2024

To better understand how soil temperature will influence the responses of boreal trees to increasing atmospheric [CO2], one-year-old jack pine (Pinus banksiana lamb.), black spruce (Picea mariana [Mill.] B.S.P.), white spruce (Picea glauca [Moench] Voss), and current-year white birch (Betula paperifera Mash) seedlings were subjected to two [CO2] (360 versus 720 μmol mol−1) and three soil temperatures (T soil = 7, 17, and 27°C initially, increased to 10, 20, and 30°C 3 months later) for 4 months. The low T soil significantly suppressed height growth, stem biomass, and total biomass in white birch, black and white spruce, root collar diameter (RCD), and foliage biomass in white birch and white spruce, as well as root biomass in white birch under both ambient and elevated [CO2] and in white spruce under ambient [CO2]. This low T soil effect was much more significant in white birch than in the conifers. The [CO2] elevation significantly increased RCD, foliar biomass, and total biomass of the four species at all soil temperatures, stem biomass of all the species at the low T soil, and the root biomass of white birch at intermediate T soil. The data suggest that the [CO2] elevation compensated for the negative effects of low T soil, e.g., the low T soil significantly decreased the height and total biomass of black and white spruce at ambient [CO2], but not at elevated [CO2]. The high T soil had much smaller negative effects on growth and biomass than did the low T soil. Jack pine was the least responsive to T soil and [CO2]. In general, the ratios of stem, foliage, and root mass to total mass were much less responsive to the treatments than total or component biomass. Neither treatment significantly affected the volume/mass ratio of the stem in any of the four species. The data suggest that white birch and white spruce will benefit the most and jack pine will benefit the least from the increasing atmospheric [CO2].
Mountain Pine Beetle-Induced Changes to Selected Lodgepole Pine Fuel Complexes within the Intermountain Region
Authors: Page Wesley Green , Jenkins Michael James
Published: April 2024

The mountain pine beetle (Dendroctonus ponderosae Hopkins) is a forest insect that infests lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) forests in the Intermountain West. The often widespread mortality caused by the mountain pine beetle has been suggested to result in significant changes to stand structure, composition, and total fuel loading; however, little quantitative information that documents these changes is available. We examined mountain pine beetle–induced changes to ground, surface, and aerial fuels in lodgepole pine stands during current epidemics and 20 years after an epidemic. Results indicated that there were statistically significant increases in the amounts of fine surface fuels in recently infested stands, i.e., those stands ≤5 years past peak mortality. In the previously infested stands, there were large increases in the amounts of dead woody fuels in all but the smallest size classes, with a 7.8-fold increase in down woody fuels ≥7.62 cm in diameter. Live shrubs and the amount of subalpine fir (Abies lasiocarpa Nutt.) regeneration were also significantly greater in the postepidemic stands. The net result of epidemic mountain pine beetle activity was a substantial change in species composition and a highly altered fuels complex in which large dead woody fuels and live surface fuels dominate.
Parameter Estimation of Base–Age Invariant Site Index Models: Which Data Structure to Use?—A Discussion
Authors: Cieszewski Chris J. , Strub Mike
Published: April 2024

We discuss here methods of comparing various approaches to site-dependent height–age model-parameter estimation. The discussion emphasis is on proper analysis of the varying parameter (VP) method versus several variants of the algebraic difference methods including one with the error in variable (EIV) theory adaptation. The study has demonstrated that, when properly considered, the VP method consistently outperforms all the other methods including the EIV method. The EIV method was tested on data with known “true model” and drastically simplified errors, and had a root mean square error (RMSE) more than 10 times worse than the VP method. All the other methods produced drastically and uniquely differing results with RMSEs varying from 26 times greater than the VP method to 300 times greater. The patterns of relatively close similarity between the EIV and the VP methods and the large differing among the other methods was similar for fittings to real data of second-rotation loblolly pine (Pinus taeda L.) from a designed experiment. The VP method is recommended for use over all the other methods as the most unbiased and as much simpler than the EIV method, which was second best.
Scaling Taper Relationships from Miniature-Scale to Operational-Scale Stands of Loblolly Pine
Authors: Sharma Mahadev , Burkhart Harold E. , Amateis Ralph L.
Published: April 2024

Taper relationships for trees grown in miniature- and operational-scale stands of loblolly pine were established using stem analysis data from 106 and 173 trees, respectively. Tree taper was modeled using segmented polynomial and dimensionally compatible taper equations. The relationship was then scaled from miniature to operational scale using the profiles obtained from these taper equations. Stump diameter was used in the taper equations instead of dbh in scaling the relationship. A simple linear regression equation described well the taper relationship between trees grown at miniature and operational scales. The fit statistics for both the segmented polynomial and dimensionally compatible taper equations were comparable at both scales. In terms of predictive accuracy, however, the segmented polynomial taper equation was superior to the dimensionally compatible taper equation in scaling the taper relationship for trees from miniature- to operational-scale plots.
Effects on Estimation Accuracy of Forest Variables Using Different Pulse Density of Laser Data
Authors: Magnusson Mattias , Fransson Johan E.S. , Holmgren Johan
Published: April 2024

Collection of airborne laser scanner data for forest inventory is becoming a common practice today. To reduce cost when laser data are collected over large areas, the flight altitude or flight speed may be increased, resulting in low pulse density laser data. The effect of using a different pulse density of laser data on estimation accuracy of forest variables was investigated at stand level. Laser data were acquired by the airborne TopEye system at a 1,200-ha forest area located in southern Sweden (58°30′N, 13°40′E). The 70 selected stands were dominated by Norway spruce [Picea abies (L.) Karst.] and Scots pine (Pinus sylvestris L.) with tree height in the range of 6–28 m (mean 19 m) and stem volume in the range of 30–620 m3 ha−1 (average 286 m3 ha−1). Regression analysis was used to establish empirical functions at stand level. The pulse density of laser data was reduced from 25,000 to 40 returns ha−1. By reducing the pulse density the root mean square error (RMSE) for the tree height and stem volume estimation increased from 0.7 to 1.8 m and from 13% to 29%, respectively. A substantial decrease in estimation accuracy of tree height and stem volume could be observed at pulse densities <80 returns ha−1 (corresponding to about 10 m between adjacent laser returns). The rapid increase in RMSE at these pulse densities could be explained by the less accurate classification of ground returns. With access to a high resolution digital elevation model the RMSE for the tree height and stem volume estimation increased from 0.7 to 1.1 m and from 13% to 23%, respectively, as an effect of the reduced pulse density. Even though the pulse density was reduced to several meters between adjacent laser returns, the estimation accuracies were equal to or better than those commonly obtained by using conventional forest inventory methods, e.g., aerial photo interpretation. This finding implies that low pulse density airborne laser scanner data could be cost efficient to use in inventory for estimation of forest variables at stand level.
Ectomycorrhizal Communities on Tree Roots and in Soil Propagule Banks along a Secondary Successional Vegetation Gradient
Authors: Yamashita Satsuki , Fukuda Kenji , Ugawa Shin
Published: April 2024

Changes in the composition of underground ectomycorrhizal communities along a secondary successional vegetation gradient were investigated in Kashiwa City, Kanto District, eastern Japan. Soil cores were sampled from the surface soils of six plots in a successional series of vegetation, and ectomycorrhizal root tips were classified into morphotypes by macroscopic observation and measurement of the internal transcribed spacer 3–4 length of rDNA. The inoculum potential of ectomycorrhizal fungi in the soils was also investigated by germinating and growing Japanese red pine seedlings in pots. The species richness of ectomycorrhizal fungi on tree roots increased along the successional gradient from the pioneer tree stage (Pinus densiflora Sieb. et Zucc. stands) to the middle stage (deciduous Quercus serrata Thunb. and Castanea crenata Sieb. stands) and then slightly decreased in the climax stage (evergreen Quercus myrsinaefolia Bl. stands). The increase in the number of ectomycorrhizal morphotypes was strongly correlated with the increase in the biomass of ectomycorrhizal trees along the succession. Ectomycorrhizal propagule banks were found in the soil of pioneer grass- and shrublands where ectomycorrhizal trees were not present. Unlike the diversity of ectomycorrhizal morphotypes on tree roots, the morphotype richness and diversity of ectomycorrhizal inocula in the soil infective to pine seedlings increased only from the grassland to the pine successional stage and not in the deciduous and evergreen-oak stages. The composition of ectomycorrhizal communities on mature trees and ectomycorrhizal propagule banks in soils showed a successional gradient along the secondary vegetation gradient, but many common morphotypes were present among the different vegetation stages.
Predicted Fire Behavior in Selected Mountain Pine Beetle–Infested Lodgepole Pine
Authors: Page Wesley , Jenkins Michael J.
Published: April 2024

Using custom fuel models developed for use with Rothermel's surface fire spread model, we predicted and compared fire behavior in lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stands with endemic, current epidemic, and postepidemic mountain pine beetle (Dendroctonus ponderosae Hopkins) populations using standardized sets of wind speeds and fuel moistures. We also compared our fire behavior results with those from standard fuel models. Results indicated that for surface fires both rates of fire spread and fireline intensities were higher in the current epidemic stands than in the endemic stands owing to increases in the amounts of fine surface fuels. In the postepidemic stands, rates of surface fire spread and fireline intensities were higher than in the endemic stands owing to decreased vegetative sheltering and its effect on mid-flame wind speed. Total heat release of surface fires, including postfrontal combustion, was also higher in the postepidemic stands owing to heavy accumulations of large diameter fuels. Crown fires were more likely to initiate in the postepidemic stands owing to greater fireline intensities and lower crown base heights. However, the critical rate of spread needed to sustain an active crown fire was higher in the postepidemic stands owing to decreased aerial fuel continuity. We suggest here that crown fire initiation in the current epidemic stands was also greater because of an abundance of dead aerial fuels; although this relationship is unclear.
Effect of Centrifugal Forces on Cluster Patterns in the Softwood Lumber Industry of the United States
Authors: Aguilar Francisco X.
Published: April 2024

Although previous reports have identified clustering in the secondary wood products industry, there are no previous studies on the factors influencing spatial patterns in the primary wood products sector. This study explores the perceptions of members of the softwood lumber industry in the United States concerning factors driving location and promoting cluster patterns in this particular industry. The analysis builds on the core-periphery framework of New Economic Geography to identify centrifugal and centripetal forces and determines the most salient advantages and disadvantages derived from industry clustering. The most essential location factors are linked to the availability of raw materials and skilled labor. The results of the factor analysis, reinforced by bootstrapping estimation, suggest that centrifugal forces outweigh centripetal forces. Greater dispersive effects of centrifugal forces result in a peripheral primary wood products industry pattern. Clustering of softwood sawmills is perceived as detrimental to this industry segment because it results in higher costs of inputs, congestion, and undesired competition. However, geographical coincidence between primary and secondary wood product manufacturers that fosters collaboration can result in an enhanced competitive industry structure.
Variation in Mechanical Properties of Selected Young Poplar Hybrid Crosses
Authors: Yu Qibin , Zhang S.Y. , Pliura Alfas , MacKay John , Bousquet Jean , Périnet Pierre
Published: April 2024

To better understand the variability in mechanical properties caused by genetic differences in hybrid poplars, modulus of elasticity and modulus of rupture in static bending were examined at two 10-year-old clonal trials located at Windsor and St-Ours, southern Quebec, Canada. The materials consisted of three hybrids, Populus deltoides × Populus nigra, Populus trichocarpa × P. deltoides, Populus maximowiczii × Populus balsamifera, and native P. deltoides. Significant differences were observed in mechanical properties among hybrids and P. deltoides. The effects of growth on the mechanical properties were inconsistent and varied considerably by site and by hybrid. Results indicated no uniform trends relating growth rate to either higher or lower modulus of elasticity/modulus of rupture. It appears that selection for strength properties may not uniformly lead to decreased growth production, especially for P. trichocarpa × P. deltoides and P. maximowiczii × P. balsamifera.
Ecological and Economic Determinants of Invasive Tree Species on Alabama Forestland
Authors: Hussain Anwar , Sun Changyou , Zhou Xiaoping , Munn Ian A.
Published: April 2024

The spread of invasive tree species has caused increasing harm to the environment. This study was motivated by the considerations that earlier studies generally ignored the role of economic factors related to the occurrence and abundance of invasive species, and empirical analyses of invasive trees on forestland have been inadequate. We assessed the impact of ecological and economic factors on the occurrence and number of invasive tree species on Alabama forestland since 1990. Count data models were used to analyze the 2004 Alabama Forest Inventory Analysis (FIA) data. The proportion of FIA plots with invasive species was 1.06% in 1990, 1.24% in 2000, and 1.35% in 2004. Occurrence of invasive trees on a plot depended on forest type (e.g., natural pines, planted pines, or oak-pines). Plots with planted pine were 171% less likely to be infested with invasive trees than otherwise similar plots. Number of invasive trees per plot was determined by a wide variety of factors, including site productivity, growing stock, stand age, ecoregion, plot proximity to metropolitan centers, ownership type, and forest management activity. The magnitude of the impact was especially large for the ownership type, with more invasive trees on private forestlands than on public lands. These findings suggest that both ecological and economic factors need to be considered in the prevention and control of invasive species invasion.
Tests of a Dynamic Programming-Based Heuristic for Scheduling Forest Core Area Production over Large Landscapes
Authors: Wei Yu , Hoganson Howard M.
Published: April 2024

Potential simplifying assumptions are presented and tested for applying a heuristic model to schedule production of core area of older forest for the Chippewa National Forest in Minnesota, recognizing approximately 67,000 analysis units and 10 10-year planning periods. The model has strong ties to optimization modeling, utilizing dynamic programming to solve overlapping and linked subproblems. Emphasis of this research is on understanding tradeoffs between solution time and nearness to optimality when large landscapes are modeled. Results show that combinations of model-simplifying assumptions can help maintain an efficient balance between computation time and model optimality. Results are sensitive to values assumed for core area, suggesting that more spatial detail is recognized with higher core area values. Results are compared along an efficiency frontier, where improvements in either computation time or management schedule value cannot be achieved without a loss in the other. Understanding the tradeoff between optimality and computation efficiency is important for model use within a larger iterative system that integrates spatial values with aspatial, forestwide management constraints.
Tradeoffs in Overstory and Understory Aboveground Net Primary Productivity in Southwestern Ponderosa Pine Stands
Authors: Sabo Kyla E. , Hart Stephen C. , Sieg Carolyn Hull , Bailey John Duff
Published: April 2024

Previous studies in ponderosa pine forests have quantified the relationship between overstory stand characteristics and understory production using tree measurements such as basal area. We built on these past studies by evaluating the tradeoff between overstory and understory aboveground net primary productivity (ANPP) in southwestern ponderosa pine forests at the landscape level and over a gradient of stand structural types and burn histories. We measured overstory and understory attributes in 2004 and 2005 in four stand structural types (unmanaged, thinned, thinned and burned, and low basal area thinned and burned) relative to a stand-replacing wildfire site. Thinning alone and with prescribed burning reduced stand-level wood and total tree production relative to unmanaged stands. Understory (herbaceous) ANPP was highest in wildfire stands and low basal area thinned and burned plots but did not differ among the other stand structural types, apparently because of high residual basal area and relatively uniform tree spacing. Contemporary ponderosa pine forests are low productivity ecosystems that exhibit a threshold response between reductions in tree density and increases in understory production at 5.9 m2 ha. We calculated the slope of the relationship between tree and herbaceous ANPP to be −0.14, which was lower than the values we estimated from other, more productive savanna ecosystems. Our results suggest that to maintain more fire-resistant and hence sustainable southwestern ponderosa pine ecosystems, tree densities need to be substantially reduced from contemporary levels. Large, landscape-level reductions in tree density will decrease total ecosystem production of this forest type, but this reduction will probably be small relative to ecosystem production losses after widespread, stand-replacing wildfires.
Protect Thy Neighbor: Investigating the Spatial Externalities of Community Wildfire Hazard Mitigation
Authors: Butry David , Donovan Geoffrey
Published: April 2024

Climate change, increased wildland fuels, and residential development patterns in fire-prone areas all combine to make wildfire risk mitigation an important public policy issue. One approach to wildfire risk mitigation is to encourage homeowners to use fire-resistant building materials and to create defensible spaces around their homes. We develop a theoretical model of interdependent household wildfire risk and mathematically introduce two new concepts of the benefits accruing from hazard mitigation: direct and spillover (indirect) damage averted. We explore how firewise communities can best spend and position mitigation resources to maximize the sum of direct and spillover damage averted. Simulating wildfire behavior within a fire-prone community, our results indicate that homeowners' wildfire risk reduction actions can have significant, positive spillover effects on the wildfire risk of neighboring houses. In such cases, individual homeowners may engage in inefficient levels of wildfire risk mitigation when viewed from the community perspective. We use a simulation approach to demonstrate that wildfire risk reduction is most effective when concentrated in houses at the interface of communities and wildlands.
Thinning Effects on Microbial Biomass, N Mineralization, and Tree Growth in a Mid-Rotation Fire-Origin Lodgepole Pine Stand in the Lower Foothills of Alberta, Canada
Authors: Tan Xiao , Chang Scott X. , Comeau Philip G. , Wang Yonghe
Published: April 2024

We examined the effects of precommercial thinning on microbial biomass C and N, rates of microbial respiration and net N mineralization, and tree growth 24 years after thinning of a 22-year-old fire-origin lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stand near Edson, Alberta. Treatments were control (unthinned) and manual-thinned (even spacing) to 1,600 trees ha−1 with thinning residue removed. Forest floor and mineral soil (0–10 and 10–20 cm) were sampled on June 15, July 26, and September 25 of the 2002 growing season for the analyses of soil chemical and biological properties, with the last set of incubated samples for determining net N mineralization rates retrieved on May 23, 2003. Forest floor mass was 16 Mg ha−1 lower in the thinned (59 Mg ha−1) than in the unthinned (75 Mg ha−1) plots. Soil moisture content in the forest floor and net N mineralization rates and available N in the mineral soil on most of the sampling dates were higher in the thinned than in the control plots. In the thinned plots, basal area and relative density were 27.7 m2 ha−1 and 54, respectively, and these were still significantly lower than values in the unthinned plots 24 years after treatment. Current annual diameter increment of the largest 1,000 trees ha−1 was greater in the thinned than in the unthinned plots in 2002–2003. Diameter growth was positively correlated with net N mineralization and soil available N. In this stand, thinning still influenced N availability and soil processes with the trees continuing to respond 24 years after thinning.
Estimating Area of Forest Change by Random Sampling of Change Strata Mapped Using Satellite Imagery
Authors: Dymond John R. , Shepherd James D. , Arnold Greg C. , Trotter Craig M.
Published: April 2024

There is worldwide interest in monitoring changes in forest area for carbon budgeting and assessing biodiversity changes. For cost-effective monitoring over large areas, automated mapping is necessary. However, the accuracy of automated mapping is rarely high enough to permit accurate estimation of changes in forest area when there is small change. In this article, we show how accurate area statistics of small change can be achieved by combining automated change mapping with stratified random sampling. The stratified random sampling can be made efficient by exhaustive sampling of a stratum with contiguous areas of apparent change greater than or equal to some lower limit (5 ha in the case presented here) and splitting the forest-to-forest stratum into large and small spectral change. Efficiency of the method is high when the exhaustively sampled stratum contains a high proportion of all real change. A regional example from New Zealand of mapping change in forest area is given. Acceptable accuracy (afforestation is estimated to ±7% of reported afforestation) from acceptable effort (10,702 sample points) is obtained, representing an efficiency gain of 78% (in terms of sample size) over simple random sampling. The method can be applied to national estimation of forest change to the same accuracy with an efficiency gain of approximately 70%. It provides a more rapid alternative to multipurpose forest inventories, which depend on intensive and expensive field data, and has significant implications for carbon accounting at regional and national scales, where rapid production of usable estimates are required for carbon exchange markets.
Seed Viability and Dispersal of the Wind-Dispersed Invasive Ailanthus altissima in Aqueous Environments
Authors: Kaproth Matthew A. , McGraw James B.
Published: April 2024

In mesic forest environments, seeds of wind-dispersed plant species may frequently be deposited in aqueous environments (e.g., lakes and rivers). The consequences of deposition in an aqueous medium depend on whether seed viability is maintained. If seeds survive there, secondary dispersal in water may transport seeds long distances to suitable habitats. Using the exotic species, tree-of-heaven (Ailanthus altissima [Mill.] Swingle), in this study we estimated seed dispersal into water as a function of distance and experimentally tested seed buoyancy, secondary dispersal, and germinability after dispersal in water and on land. We found that biologically significant numbers of seeds disperse directly into water, remain buoyant, and are transported long distances by water. Germination rates for seeds that were kept in aqueous environments (Cheat Lake and the Monongahela River, near Morgantown, WV) were found to be similar to or higher than those in nearby terrestrial controls (F = 10.94, P = 0.0057). Seeds kept in aqueous environments retained high germination rates (94.4 ± 1.1%) even after 5 months. Although A. altissima may not disperse primarily through water environments, this study suggests that secondary dispersal by water is possible and may allow for long-distance dispersal more than two orders of magnitude farther than recorded primary dispersal.
Base–Age Invariant Site Index Models from a Generalized Algebraic Parameter Prediction Approach
Authors: Wang Mingliang , Rennolls Keith , Borders Bruce E.
Published: April 2024

A simple idea is proposed to develop polymorphic base–age invariant models with multiple asymptotes: the asymptotic parameter is taken as the site-specific parameter (χ) and one of the other parameters is taken as dependent on χ as a simple power function. This approach is a constrained form of the generalized algebraic difference approach (GADA) and eliminates the requirement in previous GADA models to obtain an explicit solution for χ: χ just has to be estimated along with other parameters of the model. The approach may be used to adapt base–age specific models, developed in terms of the “parameter prediction” method, to be “base–age invariant.” The new approach and the models it produces are evaluated on data sets for Chinese fir, red alder, and birch, with models being fitted using the “dummy variable” method in which each observed data series has its own site-specific χ parameter. The base–age invariant models developed are superior to their comparable base–age specific models.
GIS-Based Modeling of Pinyon–Juniper Woodland Structure in the Great Basin
Authors: Greenwood David L. , Weisberg Peter J.
Published: April 2024

Pinyon–juniper woodlands are a dominant vegetation type across the Intermountain West, covering an estimated 30 million ha. Increases in density, cover, and aerial extent over recent decades have been associated with altered fire regimes, tree mortality, and reduced understory productivity. In our study we sought to determine how environmental factors influence woodland structure and to exploit such abiotic influences to improve our ability to model woodland structure from digital aerial photography. We developed and applied a methodology for automated tree canopy cover mapping using an object-oriented classifier. The resulting classification was used to scale up stand inventory measurements (0.1 ha) across 11 mountain ranges to a 3,250 km2 area. Predictive models were compared with field-measured values from a validation sample for tree canopy cover, basal area, height, and stand density index. Linear mixed-effects regression models demonstrated consistent relationships between woodland structure attributes and environmental variables. More productive sites supported greater tree densities, whereas less productive sites supported fewer, larger trees. Relatively weak relationships for certain variables (e.g., tree height) suggest that woodland structure-environment relationships are partially obscured by natural disturbances and land use history.
An Application of a Reduced Cost Approach to Spatial Forest Planning
Authors: Pukkala Timo , Heinonen Tero , Kurttila Mikko
Published: April 2024

The task of forest planning is to find the best combination of treatment schedules for forest stands. With many stands and several alternatives per stand the number of possible combinations becomes very large and standard heuristics for combinatorial optimization such as simulated annealing (SA), tabu search, and genetic algorithm become slow. One way to deal with the problem of large decision space is to decompose the forest-level problem into stand-level subproblems. We developed a spatial application of the decomposing technique proposed by Hoganson and Rose. This method maximizes the reduced cost (RC) of each stand. The dual prices of forest-level constraints appear in the RC function and they tie the stand-level problems together. In our spatial application of the RC method we used a multiobjective stand-level objective function. The function included spatial objective variables, the values of which depended on adjacent stands. The dual prices of nonspatial forest-level constraints were gradually adjusted by using a variant of the subgradient method, until the set of stand-level solutions fulfilled the forest-level constraints. The method was compared with a cellular automaton and the SA heuristic in a spatial problem in two different forests. The results suggest that the spatial application of the RC method is competitive with heuristics currently used in forest planning. It was slightly superior to SA in terms of the objective function value of SA. The method is easy to use because it has few parameters.
On the Use of Statistical Tests with Non-Normally Distributed Data in Landscape Change Detection
Authors: Strimbu Bogdan , Hickey Gordon , Strimbu Vladimir , Innes John
Published: April 2024

Research assessing changes of the main attributes describing forested landscapes often supply contradictory findings when viewed within an unchanging socioeconomic framework (i.e., unchanging forest management policies and no human population increase). Some studies suggest forest decline, others no change, and others expansion. We used ground-measured forest inventory data from Romania to examine the evolution of the forested landscape over a 10-year period (1993–2003), during which no substantial transformations occurred in the human population or in forest management policies. Within a repeated-measures framework, a range of parametric and nonparametric statistical tests were used to evaluate forest change. Our results revealed that significant structural changes occurred at the landscape level. The changes were detected by several multivariate and nonparametric techniques. Multivariate techniques revealed that “age class,” “phyto-climatic zone,” and “ownership type” attributes had a significant influence in delineating between the 1993 and 2003 forested landscape. The univariate nonparametric tests indicated that there are factors not considered in the planning process (such as ownership or inflation) that can lead to a significant decrease of the main quantitative forest attributes (such as canopy closure or height), a decrease undetected by the corresponding parametrical statistics. Our research revealed that even when the distribution did not exhibit significant skewness, the nonparametric techniques could be more efficient than the corresponding parametric techniques by detecting significant changes of the attributes describing the forested landscape.
Public Participation GIS: A New Method for Use in National Forest Planning
Authors: Brown Gregory G. , Reed Pat
Published: April 2024

In this article we describe and evaluate a public participation geographic information systems (PPGIS) methodology for use in national forest planning in the United States. The Internet-based mapping method collects public landscape values and special places data for input into a national forest planning decision support system. The PPGIS method presupposes that, within their existing statutory framework, national forests should be managed for compatibility with the range of values the public holds for those lands and that inadequate understanding, modeling, and documentation of place-specific forest values can negatively affect public acceptance, viability, and the usefulness of national forest plans. In this article we 1) review previous applications of landscape value mapping methods across a variety of planning applications, 2) describe the participatory, Internet mapping method used in three studies of national forests in Arizona and Oregon in 2006 and 2007, 3) present and evaluate the results to show likely future implementation constraints, and 4) based on lessons learned, describe a recommended PPGIS protocol for national forest planning. The results from the three studies demonstrate that an Internet, participatory mapping method, although not without limitations, can be effective in measuring landscape value and special place data for use in a variety of forest planning processes. Because the protocol expands and in a sense democratizes the agency's public participation process, implementation of the PPGIS protocol across the national forest system can help restore public trust in the agency's forest planning processes and forest management decisions.
A Plotless Density Estimator Based on the Asymptotic Limit of Ordered Distance Estimation Values
Authors: Kronenfeld Barry J.
Published: April 2024

Estimation of tree density from point-tree distances is an attractive option for quick inventory of new sites, but estimators that are unbiased in clustered and dispersed situations have not been found. Noting that bias of an estimator derived from distances to the kth nearest neighbor from a random point tends to decrease with increasing k, a method is proposed for estimating the limit of an asymptotic function through a set of ordered distance estimators. A standard asymptotic model is derived from the limiting case of a clustered distribution. The proposed estimator is evaluated against 13 types of simulated generating processes, including random, clustered, dispersed, and mixed. Performance is compared with ordered distance estimation of the same rank and with fixed-area sampling with the same number of trees tallied. The proposed estimator consistently performs better than ordered distance estimation and nearly as well as fixed-area sampling in all but the most clustered situations. The estimator also provides information regarding the degree of clustering or dispersion.