Conifer Cover Research Articles

The classification of late seral forests in the Pacific Northwest, USA using Landsat ETM+ imagery

To conserve the Earth's most extraordinary expressions of temperate biodiversity in the Pacific Northwest (PNW), USA, the mapping of late seral (old and mature) conifer forests plays a critical role. For this paper, we define old conifer forests as >150 years and mature conifer forest between 50 and 150 years. We offer a new Optimal Iterative Unsupervised Classification (OIUC) procedure for mapping late seral conifer forests over an eight-ecoregion area. The key steps of the OIUC classification were: (1) fully using the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) 15 m panchromatic channel merged with other 30 m bands 3 and 5 to make a pan-sharpened false color composite for high resolution image interpretation; (2) splitting the ETM+ scene by ecologically distinct areas, or ecoregions, to create relatively homologous images for classification; (3) using a procedure similar to cluster busting where multiple iterative manipulation of the ISODATA clusters was employed; and (4) edge matching of sub-scenes to form ecoregions, then later merged together to form a map for the entire PNW. Supporting data and information included ancillary spatial GIS data layers, aerial photos, Digital Ortho Quad images (DOQs), field investigations, and previously reported forest age results. Classification accuracy was assessed using 2081 stratified random locations on 105 individual DOQs covering the entire region. Approximately 4.7 million ha (∼19%) of the PNW was classified as old conifer forest (>150 years). Another 4.8 million ha (∼19%) was classified as mature conifer forest (50–150 years). Over 9.48 million ha (∼38%) of the PNW was late seral conifer forest. The extent of late seral forests (old and mature conifer cover classes) varied greatly between the eight ecoregions. The Central and Southern Cascades and Klamath–Siskiyou ecoregions contained the highest amount of late seral forest in the region. The results showed high accuracy of the late seral forest classification for the PNW with an overall accuracy of 90.72% and KAPPA test K value 0.8534. Producer's (Omission) accuracy for old and mature forests were 91.36% and 80.40%, User's (Commission) accuracy were 89.42% and 80.59%, respectively. Accuracy levels differed for the different ecoregions examined. In general, mature conifer forests exhibited higher levels of confusion than did old conifer forests, due to the spectral influences of high-density young conifer stands and terrain shadow effects. The results fill an important data gap needed for ongoing conservation planning purposes throughout the region. We found that for relatively large geographic areas the OIUC method is an efficient and cost-effective alternative that yields high quality results.

Seasonal migration patterns of female sika deer in eastern Hokkaido, Japan

Fifty‐seven female sika deer (Cervus nippon yesoensis), captured at the wintering area in the Shiranuka Hills in eastern Hokkaido, Japan, were radio‐tracked during 1997–2001 to examine the factors affecting seasonal migration at the individual‐landscape level. Ten of the 57 deers migrated between low‐altitude summer home ranges and intermediate‐altitude winter home ranges (the upward migrants). Twenty‐nine migrated between high‐altitude summer home ranges and intermediate‐altitude winter home ranges (the downward migrants). Twelve used the intermediate‐altitude home ranges all year round (the non‐migrants). The remaining six were unknown. The summer home ranges of deer were widely scattered over an area of 5734 km2. Migration distances ranged between 7.2 and 101.7 km. Deer showed high site fidelities to their seasonal home ranges. The upward migrants wintered in areas of less snow, higher quality of bamboo grass, and more coniferous cover than their summer home ranges. The downward migrants wintered in areas of less snow, higher quality of bamboo grass, higher winter temperature, and more southern slopes, but less coniferous cover than their summer home ranges. The non‐migrants used year‐round ranges with little snow, high quality of bamboo grass, and sufficient coniferous cover. We suggest that snow cover and bamboo grass are the factors affecting seasonal migration of the population and that coniferous cover is another factor for the upward migration.

The influence of catchment characteristics on the seasonality of carbon and nitrogen species concentrations in upland rivers of Northern Scotland

Data from 13 catchments with no arable land in Northern Scotland were used to develop empirical linear regression models of average monthly NO3 − concentrations and average summer and winter concentrations for NH4 +, dissolved organic N (DON) and dissolved organic carbon (DOC) as a function of catchment characteristics. All catchments displayed a pronounced seasonal NO3 − cycle. Variation in monthly mean NO3 − concentration within and between catchments could be predicted from mean monthly air temperature using separate regression equations for temperatures < and ≥ 5 °C. Soil type, climate and land use influenced NH4 + concentrations. In summer, concentrations of NH4 + were largest in catchments with extensive areas of brown forest soils, which are less acidic and more base-rich than other upland soils. However, concentrations declined with increasing conifer cover and summer rainfall. In winter, however, % conifer cover had a positive effect, while higher temperature and higher humus iron podzol cover had negative influences. DON concentration decreased with increasing catchment elevation in both summer and winter. Surprisingly, concentrations of DON only displayed a positive relationship with percentage peat cover in the summer. The most important factor controlling DOC concentration was soil type, with a positive relationship being observed between DOC and peat and humus iron podzol coverage. Elevation was also important, but only in the winter when concentrations were negatively correlated with maximum catchment elevation. Overall, multivariate regression equations explained the spatial and seasonal variability in N species concentrations over a range of catchments within Northern Scotland.

UNDERSTORY VEGETATION AND ENVIRONMENT RESPONSES TO TILLAGE, FOREST HARVESTING, AND CONIFER PLANTATION DEVELOPMENT

Increasing demand to conserve biodiversity in managed forests necessitates better understanding of the impacts of forestry practices on the species‐rich herbaceous layer. We compared composition and diversity of understory vegetation, environmental features, and stand structure of forests in New Brunswick, Canada, under four different management scenarios, including: young (24–66 yr) naturally regenerated forests and conifer plantations (19–64 yr) established after clear‐cutting, mature (77–100 yr) naturally regenerated forests originating from natural disturbance (insect defoliation), and old‐field plantations (31–77 yr) established on abandoned agricultural fields. The objectives were to determine how plant composition, forest structure, and microenvironment differed among stand types and which environmental or structural features were related to understory species. Detrended correspondence analysis (DCA) and multiresponse permutation procedure (MRPP) indicated that stand types differed in species composition and environments. Plantations were significantly lower in density of snags, deciduous canopy cover, and leaf substrate, and higher in coniferous canopy cover and needle, twig, and moss substrates than the natural stands. Old‐field plantations had less cover of pits and mounds than all other stand types. Mature natural stands contained the greatest amount of coarse woody debris (CWD) in all decay classes and snags &gt;14 cm diameter, and the lowest density of trees &gt;5 cm diameter and moss cover. Canonical correspondence analysis (CCA) showed that species in both natural stand types are associated with decayed CWD, deciduous cover, and leaf substrate. Species in cutover plantations were associated with coniferous cover and needle substrate. Species composition in old‐field plantations was distinct, with the lowest species richness and diversity of all stand types. We present a conceptual model illustrating the initial direct effects of previous land use and harvesting or postharvest treatments and the subsequent indirect effects associated with plantation or natural stand development on environmental features and understory vegetation. We recommend extending plantation harvest cycles to facilitate reestablishment and expansion of plant populations and maintaining diverse tree canopy composition, coarse woody debris, and pit and mound topography to sustain critical habitat for vascular understory plant species in managed forests.

Nitrogen Export from Forested Watersheds in the Oregon Coast Range: The Role of N 2 -fixing Red Alder

Variations in plant community composition across the landscape can influence nutrient retention and loss at the watershed scale. A striking example of plant species importance is the influence of N2-fixing red alder (Alnus rubra) on nutrient cycling in the forests of the Pacific Northwest. To understand the influence of red alder on watershed nutrient export, we studied the chemistry of 26 small watershed streams within the Salmon River basin of the Oregon Coast Range. Nitrate and dissolved organic nitrogen (DON) concentrations were positively related to broadleaf cover (dominated by red alder: 94% of basal area), particularly when near-coastal sites were excluded (r 2 = 0.65 and 0.68 for nitrate-N and DON, respectively). Nitrate and DON concentrations were more strongly related to broadleaf cover within entire watersheds than broadleaf cover within the riparian area alone, which indicates that leaching from upland alder stands plays an important role in watershed nitrogen (N) export. Nitrate dominated over DON in hydrologic export (92% of total dissolved N), and nitrate and DON concentrations were strongly correlated. Annual N export was highly variable among watersheds (2.4–30.8 kg N ha−1 y−1), described by a multiple linear regression combining broadleaf and mixed broadleaf–conifer cover (r 2 = 0.74). Base cation concentrations were positively related to nitrate concentrations, which suggests that nitrate leaching increases cation losses. Our findings provide evidence for strong control of ecosystem function by a single plant species, where leaching from N saturated red alder stands is a major control on N export from these coastal watersheds.

Germinable soil seed‐bank of former grassland converted to coniferous plantation

The influence of afforestation with cedars on field layer vegetation and on the germinable soil seed‐bank were investigated along a 60‐m transect merging from open grassland to sparse and dense canopy cover. A total of 132 species were found, 76 in the seed‐bank and 109 in the vegetation, with 53 species in common. Conifer cover was not found to be associated with a decrease in total number of species in the vegetation or seed‐bank, but the mean number of species in the vegetation, total cover in field layer vegetation and mean number of individuals in the seed‐bank decreased significantly from grassland to forest stands. The grassland seed‐bank was dominated by Saxifraga tridactylites and Veronica agrestis; the seed‐bank of plots of scattered cedars was dominated by Trifolium incarnatum ssp. molinerii; and that of dense cedar plantations was dominated by Campanula rapunculus. The number and cover of grassland species of field layer vegetation decreased in the forest, with respect to open grassland, and the same trend was found for density of individuals in the seed‐bank. It is concluded that grassland restoration by cutting cedars cannot rely on the presence of grassland species in the soil seed‐bank.

Predicting understory light microclimate from stand parameters in young paper birch ( Betula papyrifera Marsh.) stands

On productive sites, young paper birch ( Betula papyrifera Marsh.) outgrows most of the conifers with which it is associated. Due to its dominant position in the canopy, and the potentially high densities of birch regeneration found on some sites, its presence may lead to a reduction in the amount of light reaching subordinate conifers. To evaluate the potential use of stand attributes for estimating competition for light and understory light levels, we measured fractional transmittance of light (DIFN 1) using Licor LAI-2000 Plant Canopy Analyzers, at a height of 1 m under the canopies of nine 10–40-year-old paper birch stands in southern interior BC. Various measures of broadleaf and conifer abundance were made at each of the 55 sample points where light measurements were taken. Vertical light gradients were also measured to a height of 8 m within birch canopies at four of the nine sites. Regression models were developed to predict understory light availability from broadleaf and conifer abundance. The models that best-fit the data were based on broadleaf basal area (BA b), and included either conifer cover ( C c) ( R 2=0.83) or conifer basal area (BA c) ( R 2=0.80). Broadleaf density (TPH b) alone was a poor predictor of understory light, but in combination with broadleaf quadratic mean diameter (QMD b) or height of the tallest broadleaf (HT b) the models improved ( R 2>0.85). Light availability increased rapidly with relative height in birch canopies, especially where transmittance to the understory was low; at 35% of the height from live crown base to top of the canopy (relative height of 0.35), approximately 80% full light was available. A diagrammatic representation of the relationship between DIFN 1, QMD b and TPH b is presented as a potential tool for the development of stand-tending prescriptions. DIFN 1, BA b and TPH b were all highly variable across individual sites, indicating that the models should be applied at the microsite level.

HABITAT USE AND PRODUCTIVITY OF SHARP-SHINNED HAWKS NESTING IN AN URBAN AREA

Abstract We measured productivity and vegetation parameters of habitat quality at 16 Sharp-shinned Hawk (Accipiter striatus) nests in and near the greater Montreal area in order to evaluate nesting habitat use and its possible relationship to reproductive success in an urban setting. Mean clutch size was 4.4 and hatching success was 3.8 eggs per nest. At least one egg hatched in 11 of 16 nests (68.8%), 10 (62.5%) pairs raised young to a bandable age (≥10 days old), and 8 (50%) pairs successfully produced at least one fledgling. Immature individuals comprised 33.3% of male and 38.5% of female breeders. Mean values in the habitat assessment included nest tree height, 14.0 m; tree density, 955/ha; total canopy cover, 88.1%; coniferous cover, 39.7%; mean dbh, 17.6 cm; and distance to the nearest forest opening, 19.7 m. Sharp-shinned Hawks nested in a range of forest types, from mature conifer plantations to young, almost purely deciduous stands, and this population exhibited considerable flexibility with resp...

Mapping vegetation in Yellowstone National Park using spectral feature analysis of AVIRIS data

Knowledge of the distribution of vegetation on the landscape can be used to investigate ecosystem functioning. The sizes and movements of animal populations can be linked to resources provided by different plant species. This paper demonstrates the application of imaging spectroscopy to the study of vegetation in Yellowstone National Park (Yellowstone) using spectral feature analysis of data from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data, acquired on August 7, 1996, were calibrated to surface reflectance using a radiative transfer model and field reflectance measurements of a ground calibration site. A spectral library of canopy reflectance signatures was created by averaging pixels of the calibrated AVIRIS data over areas of known forest and nonforest vegetation cover types in Yellowstone. Using continuum removal and least squares fitting algorithms in the US Geological Survey's Tetracorder expert system, the distributions of these vegetation types were determined by comparing the absorption features of vegetation in the spectral library with the spectra from the AVIRIS data. The 0.68 μm chlorophyll absorption feature and leaf water absorption features, centered near 0.98 and 1.20 μm, were analyzed. Nonforest cover types of sagebrush, grasslands, willows, sedges, and other wetland vegetation were mapped in the Lamar Valley of Yellowstone. Conifer cover types of lodgepole pine, whitebark pine, Douglas fir, and mixed Engelmann spruce/subalpine fir forests were spectrally discriminated and their distributions mapped in the AVIRIS images. In the Mount Washburn area of Yellowstone, a comparison of the AVIRIS map of forest cover types to a map derived from air photos resulted in an overall agreement of 74.1% (kappa statistic=0.62).

Songbird abundance in clear-cut and burned stands: a comparison of natural disturbance and forest management

To evaluate the efficacy of forest management to emulate natural disturbance, we compared bird abundances among burned and clear-cut, former black spruce (Picea mariana (Mill.) BSP) sites, after 5, 14, and 27 years of succession. Total bird density was lower in clear-cut sites resulting from fewer hermit thrushes, yellow warblers, Swainson's thrushes, and fox sparrows. Hermit thrushes were positively correlated with snag density while yellow warblers and Swainson's thrushes were positively associated with deciduous tree cover and negatively correlated with conifer cover. Only yellow-rumped warblers had higher densities on clear-cut sites, likely due to greater conifer cover. Bird densities and species richness peaked in the 14-year-old burns and exceeded that of mature forests reported for Labrador. This demonstrates the importance of natural early successional forests for birds. Although logged areas support several species found in natural young burns, logging does not precisely mimic fire. This suggests that forest managers should allow some forests to burn naturally.

Factors affecting intra- and inter-specific variations in the difference between alert distances and flight distances for birds in forested habitats

Studies of escape from predators have usually focused on fleeing. We studied intra- and inter-specific variations in a previous level of decision-making during predator–prey encounters by determining the difference between the distance at which a predator is detected and the distance at which the prey flees from the predator (buffer distance). We measured buffer distances of four bird species (ground foragers) living in forested habitats (wooded recreational parks) to approaching humans. Buffer distances increased with group size and temperature, and this was probably related to dilution of the predation risk and a higher risk of heat stress, respectively. Buffer distances decreased with shrub and coniferous cover, probably because of increased visual obstruction, and increased with tree height, probably because of the increased security provided by taller trees. Grass cover increased buffer distances of wood pigeons (Columba palumbus) but decreased those of house sparrows (Passer domesticus) and magpies (Pica pica); this may be related to higher food availability, i.e., vegetation in grassy areas for wood pigeons and food left by humans in areas with bare ground for house sparrows and magpies. Buffer distances of blackbirds (Turdus merula) and house sparrows were greater in highly visited parks, which may be related to habituation. Finally, larger species showed greater buffer distances, landed farther away, used higher landing substrates (trees), and flew higher, probably because they need to ensure a certain margin of security from predators. Alternatively, the increased buffer distances of large species may be related to the increasing energy expenditure of flight. The buffer distance appears to be a good indicator of tolerance toward predators and (or) risk taken by prey after detecting predators.

Nested patterns of species distribution and winter flock occurrence of insectivorous birds in a fragmented landscape

The goal of this paper is to evaluate whether the probabilities of aggregating in flocks are dependent on the patterns of species distribution across the landscape. I analyzed winter species distribution and flock occurrence (flock formation in a given fragment) at the community and individual species levels of a guild of small insectivorous birds in a fragmented landscape. Species distributed following a nested pattern, which was mainly affected by fragment size. Flock occurrence (single- plus mixed-species flocks) followed a nested pattern, such that the probability of joining flocks was affected by the distribution of species across the landscape. However, when analyzed separately, single-species flock occurrence showed a nested pattern, but mixed-species flock occurrence followed a random pattern. Fragment size and total bird density (as an indicator of the availability of individuals to join flocks) accounted for nestedness. At the individual species level, conspecific and heterospecific densities were the foremost factors increasing flock occurrence probabilities, suggesting that species tended to aggregate when there was an increase in the local availability of individuals. Fragment size and habitat structure (coniferous cover and number of thick trees) also increased flock occurrence, likely because of higher resource availability, which allowed the colonization of more species and individuals. Greater isolation reduced flock occurrence, maybe as a result of lower availability of individuals in distant fragments. Overall, fragmentation conditions can disrupt flocking behaviour of small insectivorous species, which could decrease survival and increase predation risk during winter. Keywords: nestedness, flock occurrence, fragmentation, insectivorous birds, winter flocks.

Alert distance as an alternative measure of bird tolerance to human disturbance: implications for park design

Animal tolerance to human approaches may be used to establish buffers for wildlife that can minimize the probability that animals will be disturbed by human activity. Alert distance (the distance between an animal and an approaching human at which point the animal begins to exhibit alert behaviours to the human) has been proposed as an indicator of tolerance mainly for waterbirds; however, little is known about its utility for other bird species. The factors that influenced alert distances of four bird species to pedestrian approaches in five large wooded fragments in the city of Madrid (Spain) were analysed. Location of human activity affected only Passer domesticus alert distances, which increased in the proximity of pathways. Habitat structure modified alert distances of all the species (Passer domesticus, Turdus merula, Columba palumbus, and Pica pica), increasing bird tolerance with greater availability of escape cover (shrub and coniferous cover, and shrub height). Alert distances varied among species, with large species being less tolerant of human disturbance than small ones. Alert distance appears to be a more conservative indicator of tolerance than flight distances, because it includes a buffer zone (the difference between alert and flight distance) in which birds may adapt their reaction to the behaviour of visitors. Alert distance may be used in the determination of minimum approaching areas, allowing people to enjoy their visit to parks, and birds to use patches for foraging and breeding without being displaced.

Modelling forest cover attributes as continuous variables in a regional context with Thematic Mapper data

We modelled forest vegetation attributes as continuousvariables across western Oregon using a multi-image mosaic of Thematic Mapper (TM) data. Four specie c attributes were modelled using regression analysis: percent green vegetation cover, percent conifer cover, conifer crown diameter, and conifer stand age. Reference data for the cover and diameter attributes were derived from airphotos, and existing agency polygon databases were used for stand age. We developed and applied a new method for regional mapping called applied radio- metric normalization. The method involved development of a set of models for a centrally located 'source' scene which were then extended to 'destination' scenes (neighboring scenes in the TM mosaic). Use of airphotos and existing digital databases in combination with applied radiometric normalization translates to a cost-eVective procedure for regional mapping with TM data. Modelling forest attributes as continuous variables enables creation of a e exible forest cover information base, containing important fundamental building blocks for a variety of related classie cation schemes.

The relative importance of fire and watercourse proximity in determining stand composition in mixed conifer riparian forests

Factors related to the composition of riparian forest stands on three streams in the northern Sierra Nevada mixed conifer forest type were related to proximity to the water course and years since fire. Using a linear regression analysis 46 variables were correlated to the natural log of distance from the thalweg “ln(distance)” including a highly significant positive correlation to dominance and percent canopy cover of conifers, and a significant negative correlation to the same variables when applied to hardwoods. Twenty six variables were correlated to years since fire “years” including similar correlations to the dominance and cover of hardwood and conifer species. However, the significance of the correlation and the degree of sample variability described by fire age was relatively low in comparison to that found for distance from the thalweg. In addition the relative frequency of fire scars increased in a linear fashion with distance from the watercourse. The results of this study indicate that the importance of fire as a determining influence on forest composition declines in proximity to the riparian zone.

A TM-based hardwood-conifer mixture index for closed canopy forests in the Oregon Coast Range

The purpose of this study was to develop and evaluate a multi-spectral vegetation index for quantifying relative amounts of hardwood and conifer cover from Thematic Mapper (TM) imagery. We focused on closed canopy forests in the Oregon Coast Range, where hardwood, conifer, and mixed stand conditions are prevalent. An approach based on the Gramm-Schmidt orthogonalization process was used to derive three different hardwood-conifer mixture indices (HCMIs). Using correlation and regression analyses, the capacity of these indices to predict closed canopy hardwood percentage was compared with three other groups of spectral variables: (1) the untransformed TM reflectance bands, (2) the Tasseled Cap indices of brightness, greenness, and wetness, and (3) the first three principal components of closed canopy forest reflectance. Results show that while similar amounts of information were explained by HCMI, TM band, Tasseled Cap, and principal component models, only predictions derived from the HCMI1 and HCMI2 variab...

Developing a habitat model for the endangered Virginia northern flying squirrel ( Glaucomys sabrinus fuscus) in the Allegheny Mountains of West Virginia

We examined occurrence patterns and habitat data for the Virginia northern flying squirrel ( Glaucomys sabrinus fuscus) in the central Appalachian Mountains of West Virginia, USA with the intent to develop a habitat model. Topographic conditions (elevation, landform index, surface curvature, slope gradient and aspect) and proximity to coniferous cover were evaluated for three study areas where flying squirrel presence has been documented via nest box surveys. In our model, Virginia northern flying squirrel presence was associated with proximity to conifer cover ( P<0.001), but not to any other habitat variables tested. We developed a logistic regression model and implemented that within a geographic information system to delineate potential habitat. Statistical relations were not sufficient to predict flying squirrel occurrence with a reasonable degree of confidence. Current nest box monitoring efforts provide needed year-to-year population trend information, however, they are not sufficient to delineate potential habitat using quantitative approaches. More detailed micro- and macro-habitat relationship studies of the Virginia northern flying squirrel will be necessary for successful management and eventual recovery of this endangered species.

A TM-based hardwood-conifer mixture index for closed canopy forests in the Oregon Coast Range

The purpose of this study was to develop and evaluate a multi-spectral vegetation index for quantifying relative amounts of hardwood and conifer cover from Thematic Mapper (TM) imagery. We focused on closed canopy forests in the Oregon Coast Range, where hardwood, conifer, and mixed stand conditions are prevalent. An approach based on the Gramm-Schmidt orthogonalization process was used to derive three different hardwood-conifer mixture indices (HCMIs). Using correlation and regression analyses, the capacity of these indices to predict closed canopy hardwood percentage was compared with three other groups of spectral variables: (1) the untransformed TM reflectance bands, (2) the Tasseled Cap indices of brightness, greenness, and wetness, and (3) the first three principal components of closed canopy forest reflectance. Results show that while similar amounts of information were explained by HCMI, TM band, Tasseled Cap, and principal component models, only predictions derived from the HCMI1 and HCMI2 variables were unbiased with respect to topographic effects.

Modelling forest cover attributes as continuous variables in a regional context with Thematic Mapper data

We modelled forest vegetation attributes as continuous variables across western Oregon using a multi-image mosaic of Thematic Mapper (TM) data. Four specific attributes were modelled using regression analysis: percent green vegetation cover, percent conifer cover, conifer crown diameter, and conifer stand age. Reference data for the cover and diameter attributes were derived from airphotos, and existing agency polygon databases were used for stand age. We developed and applied a new method for regional mapping called applied radiometric normalization. The method involved development of a set of models for a centrally located 'source' scene which were then extended to 'destination' scenes (neighboring scenes in the TM mosaic). Use of airphotos and existing digital databases in combination with applied radiometric normalization translates to a cost-effective procedure for regional mapping with TM data. Modelling forest attributes as continuous variables enables creation of a flexible forest cover information base, containing important fundamental building blocks for a variety of related classification schemes.

A Neural Network Method for Mixture Estimation for Vegetation Mapping

While most forest maps identify only the dominant vegetation class in delineated stands, individual stands are often better characterized by a mix of vegetation types. Many land management applications, including wildlife habitat studies, can benefit from knowledge of mixes. This article examines various algorithms that use data from the Landsat Thematic Mapper (TM) satellite to estimate mixtures of vegetation types within forest stands. Included in the study are maximum likelihood classification and linear mixture models as well as a new methodology based on the ARTMAP neural network. Two paradigms are considered: classification methods, which describe stand-level vegetation mixtures as mosaics of pixels, each identified with its primary vegetation class; and mixture methods, which treat samples as blends of vegetation, even at the pixel level. Comparative analysis of these mixture estimation methods, tested on data from the Plumas National Forest, yields the following conclusions: 1) Accurate estimates of proportions of hardwood and conifer cover within stands can be obtained, particularly when brush is not present in the understory; 2) ARTMAP outperforms statistical methods and linear mixture models in both the classification and the mixture paradigms; 3) topographic correction fails to improve mapping accuracy; and 4) the new ARTMAP mixture system produces the most accurate overall results. The Plumas data set has been made available to other researchers for further development of new mapping methods and comparison with the quantitative studies presented here, which establish initial benchmark standards.