Estimated Volume Loss Research Articles

In situ quantitative topographic measurement and corrosion behaviour of low carbon steel in chloride solutions

ABSTRACT This study applied a novel in situ spectral modulation interferometry (SMI) technique to quantitatively measure the spatiotemporal corrosion kinetics on the surface of low carbon steel. The 3D topography map showed an early formation of localised shallow pits on the surface subjected to a chloride-free solution. In contrast, the steel samples in chloride-enriched solution revealed early-age microcracks or intergranular defective sites. The quantitative analysis of the height profile data (acquired from SMI) verified the heterogeneity of the corrosion process of these samples susceptible to pitting corrosion and intergranular corrosion behaviour. The estimated volume loss followed a similar trend to the 3D surface topography data. Still, a distinct behaviour in the volume loss was observed when compared to the void volume obtained from the electrochemical data.

EPB tunneling in cohesionless soils: A study on Tabriz Metro settlements

A case study of monitoring and analysis of surface settlement induced by tunneling of Tabriz metro line 2 (TML2) is presented in this paper. The TML2 single tunnel has been excavated using earth pressure balanced TBM with a cutting-wheel diameter of 9.49 m since 2015. Presented measurements of surface settlements, were collected during the construction of western part of the project (between west depot and S02 station) where the tunnel was being excavated in sand and silt, below the water table and at an average axis depth of about 16 m. Settlement readings were back-analyzed using Gaussian formula, both in longitudinal and transversal directions, in order to estimate volume loss and settlement trough width factor. In addition to settlements, face support and tail grouting pressures were monitored, providing a comprehensive description of the EPB performance. Using the gap model, volume loss prediction was carried out. Also, COB empirical method for determination of the face pressure was employed in order to compare with field monitored data. Likewise, FE simulation was used in various sections employing the code Simulia ABAQUS, to investigate the efficiency of numerical modelling for the estimating of the tunneling induced-surface settlements under such a geotechnical condition. In this regard, the main aspects of a mechanized excavation were simulated. For the studied sections, numerical simulation is not capable of reproducing the high values of in-situ-measured surface settlements, applying Mohr-Coulomb constitutive law for soil. Based on results, for the mentioned case study, the range of estimated volume loss mostly varies from 0.2% to 0.7%, having an average value of 0.45%.

Tribocorrosion of hard-on-hard total hip replacements with metal and ceramic counterfaces under standard and adverse loading conditions

28mm Metal-on-Metal (MoM) and Metal-on-Ceramic (MoC) Total Hip Replacements were articulated to 1 million cycles under both Standard Gait and Microseparation conditions. The hip simulator was fully instrumented with a three-electrode electrochemical cell to facilitate monitoring of corrosive degradation. The estimated volume loss from corrosion at the bearing surface was seen to increase by nearly an order of magnitude for both devices, representing as much as 17% of total degradation. Anodic current transients also displayed near order of magnitude increases in the peak current for both bearing couples. An adverse loading scenario could cause as much as an order of magnitude increase in the metallic ions released into the joint capsule as well as an increased volume of wear debris.

Hard pine stem rusts on lodgepole pine at a site-preparation study in sub-boreal British Columbia: effects over 24 years

Site preparation can improve lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Watson) survival and growth; however, we lack information regarding possible interactions between treatment effects and the impacts of western gall rust (Endocronartium harknessii (J.P. Moore) Y. Hirats.) and comandra blister rust (Cronartium comandrae Peck). Mechanical and burning techniques examined over 24 years at a sub-boreal British Columbia site did not significantly increase rust infection rates or characteristics relative to an untreated control. Most infection occurred before age 10 years and at heights <2 m. By age 24 years, 22% and 10% of pine had sustained at least one western gall rust or comandra blister rust stem infection, respectively, but only 4% of western gall rust infected trees were dead, compared with 60% of comandra blister rust infected trees. Exploratory regression analysis of the relationship between tree volume and percent stem encirclement and infection height suggested that volume of 24-year-old pine infected with western gall rust averaged 8% less than the corresponding volume of uninfected trees. Over 24 years, estimated stand-level, rust-related volume loss was 8.4%, with the majority due to mortality from comandra blister rust. One-fifth of estimated volume loss was provisionally attributed to growth reductions among live western gall rust infected pine.

Glacier status and contribution to streamflow in the Olympic Mountains, Washington, USA

AbstractThe Olympic Peninsula, Washington, USA, currently holds 184 alpine glaciers larger than 0.01 km2 and their combined area is 30.2 ± 0.95 km2. Only four glaciers are >1 km2 and 120 of the others are <0.1 km2. This represents a loss of 82 glaciers and a 34% decrease in combined area since 1980, with the most pronounced losses occurring on south-facing aspects and in the more arid northeastern part of the range. Annual rate of loss in glacier area for seven of the largest glaciers accelerated from 0.26 km2 a−1 (1900–80) to 0.54 km2 a−1 (1980–2009). Thinning rates on four of the largest glaciers averaged nearly 1 ma−1 from 1987 to 2010, resulting in estimated volume losses of 17–24%. Combined glacial snow, firn and ice melt in the Hoh watershed is in the range 63–79 ± 7 × 106 m3, or 9–15% of total May–September streamflow. In the critical August–September period, the glacial fraction of total basin runoff increases to 18–30%, with one-third of the water directly from glacial ice (i.e. not snow and firn). Glaciers in the Elwha basin produce 12–15 ± 1.3 × 106 m3 (2.5–4.0%), while those in the Dungeness basin contribute 2.5–3.1 ± 0.28 × 106 m3 (3.0–3.8%).

TBM tunnelling-induced settlements in coarse-grained soils: The case of the new Milan underground line 5

In this paper measurements of tunnelling-induced settlements collected during the construction of the new Milan underground line 5 are presented. The twin tunnels are being excavated in coarse-grained soils partially under the water table with an earth pressure balance (EPB) machine. In the following the attention is given only to the monitoring data recorded under free-field conditions (i.e. no structure on the soil surface) during and after the construction of the first tunnel. Settlement measurements are back-analysed using the classical Gaussian empirical predictions, both in the transverse and longitudinal directions, providing a very detailed description of the EPB tunnelling performance under such geotechnical conditions. In particular, a translated Gaussian cumulative curve, to be related to the influence of pressure applied at the face, is proposed to better match the evolution of settlements during tunnel advancement. Finally, the influence of different excavation parameters (such as face pressure, grouting pressure, machine thrust) on the estimated volume loss and shape of subsidence trough is investigated.

Tendon Fascicles Exhibit a Linear Correlation Between Poisson's Ratio and Force During Uniaxial Stress Relaxation

The underlying mechanisms for the viscoelastic behavior of tendon and ligament tissue are poorly understood. It has been suggested that both a flow-dependent and flow-independent mechanism may contribute at different structural levels. We hypothesized that the stress relaxation response of a single tendon fascicle is consistent with the flow-dependent mechanism described by the biphasic theory (Armstrong et al., 1984, "An Analysis of the Unconfined Compression of Articular Cartilage," ASME J. Biomech. Eng., 106, pp. 165-173). To test this hypothesis, force, lateral strain, and Poisson's ratio were measured as a function of time during stress relaxation testing of six rat tail tendon fascicles from a Sprague Dawley rat. As predicted by biphasic theory, the lateral strain and Poisson's ratio were time dependent, a large estimated volume loss was seen at equilibrium and there was a linear correlation between the force and Poisson's ratio during stress relaxation. These results suggest that the fluid dependent mechanism described by biphasic theory may explain some or all of the apparent viscoelastic behavior of single tendon fascicles.

Monitoring thickness and volume changes of the Dongkemadi Ice Field on the Qinghai-Tibetan Plateau (1969–2000) using Shuttle Radar Topography Mission and map data

This paper presents the first measurement of multi-decadal thickness and volume changes (1969–2000) of the Dongkemadi Ice Field (DIF) in the Tanggula Mountains, central Qinghai-Tibetan Plateau, China, using multi-source remote sensing data. These include the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) acquired in February, 2000, a DEM generated by digitising analogue topographic maps from 1969, and Landsat ETM+ imagery from 2000. Digital glacier outlines and GIS-based processing were used to calculate an elevation difference map to evaluate the relative elevation error of these two DEMs over ice-free areas. This method was also used to identify regions of glacier elevation thinning and thickening corresponding to glacier mass loss and gain. Analysis of 67,520 points on flat grass and rock terrain surrounding the DIF, with a slope less than 25°, showed a mean elevation difference of –0.90 m and a standard deviation of 5.58 m. A thickness change error within ±6 m was estimated. Between 1969 and 2000, 76.51% of the whole DIF area appeared to be thinning while 23.49% showed thickening. The average glacier surface thinning was –12.58 m with a standard deviation of 18.29 m and the estimated volume loss was 1.17 km3. The standard deviation of volume change was 0.0006 km3 over the DIF. A thinning rate up to 0.41±0.194 m a−1 or 0.038 km3 a−1 for the volume loss was observed for the whole ice field, which seems to be evidence for the ongoing retreat of glaciers on the Qinghai-Tibetan Plateau. It was found that the spatial thickness change pattern derived from the remote sensing method was consistent with the thickness change results of the Small Dongkemadi Glacier (SDG) from field measurements. The estimated error of the annual thickness change rate was on the order of 5%. The relationship between elevation change and absolute glacier elevation over typical glaciers was also analysed, showing considerable variability. These changes have possibly resulted from increased temperature and decreased precipitation in this region.

Functional Recovery After Partial Nephrectomy: Effects of Volume Loss and Ischemic Injury

We used what is to our knowledge a new method to estimate volume loss after partial nephrectomy to assess the relative contributions of ischemic injury and volume loss on functional outcomes. We analyzed the records of 301 consecutive patients who underwent conventional partial nephrectomy between 2007 and 2010 with available data to meet inclusion criteria. Percent functional volume preservation was measured at a median of 1.4 years after surgery. Modification of diet in renal disease-2 estimated glomerular filtration rate was measured preoperatively and perioperatively, and a median of 1.2 years postoperatively. Statistical analysis was done to study associations. Hypothermia or warm ischemia 25 minutes or less was applied in 75% of cases. Median percent functional volume preservation was 91% (range 38%-107%). Percent glomerular filtration rate preservation at nadir and late time points was 77% and 90% of preoperative glomerular filtration rate, respectively. On multivariate analysis percent functional volume preservation and warm ischemia time were associated with nadir glomerular filtration rate while only percent functional volume preservation was associated with late glomerular filtration rate (each p <0.001). Late percent glomerular filtration rate preservation and percent functional volume preservation were directly associated (p <0.001). Recovery of function to 90% or greater of percent functional volume preservation predicted levels was observed in 86% of patients. In patients with de novo postoperative stage 3 or greater chronic kidney disease, percent functional volume preservation and Charlson score were associated with late percent glomerular filtration rate preservation. Warm ischemia time was not associated with late functional glomerular filtration rate decreases in patients considered high risk for ischemic injury. In this cohort volume loss and not ischemia time was the primary determinant of ultimate renal function after partial nephrectomy. Technical modifications aimed at minimizing volume loss during partial nephrectomy while still achieving negative margins may result in improved functional outcomes.

Constraints on the origin and evolution of Iani Chaos, Mars

[1] The origin mechanisms and geologic evolution of chaotic terrain on Mars are poorly constrained. Iani Chaos, located at the head Ares Vallis, is among the most geomorphologically complex of the chaotic terrains. Its morphology is defined by (1) multiple, 1 to 2 km deep basins, (2) flat-topped, fractured plateaus that are remnants of highland terrain, (3) knobby, fractured remnants of highland terrain, (4) plateaus with a knobby surface morphology, (5) interchaos grooved terrain, (6) interior layered deposits (ILDs), and (7) mantling material. Topography, the observed geomorphology, and measured fracture patterns suggest that the interchaos basins formed as a result of subsurface volume loss and collapse of the crust, likely owing to effusion of groundwater to the surface. Regional patterns in fracture orientation indicate that the basins developed along linear zones of preexisting weakness in the highland crust. Multiple overlapping basins and fracture systems point to multiple stages of collapse at Iani Chaos. Furthermore, the total estimated volume loss from the basins (104 km3) is insufficient to explain erosion of 104–105 km3 of material from Ares Vallis by a single flood. Comparisons with the chronology of Ares Vallis indicate multiple water effusion events from Iani Chaos that span the Hesperian, with termination of activity in the early Amazonian. Recharge of groundwater through preexisting fracture systems may explain this long-lived, but likely episodic, fluvial activity. Late-stage, early to middle Amazonian aqueous processes may have deposited the ILDs. However, the topography data indicate that the ILDs did not form within lacustrine environments.

Planimetric and volumetric glacier changes in the Khumbu Himal, Nepal, since 1962 using Corona, Landsat TM and ASTER data

AbstractMultitemporal space imagery from 1962 (Corona KH-4), 1992 (Landsat TM), 2001 and 2005 (Terra ASTER) was used to investigate the glacier changes in the Khumbu Himal, Nepal. The ice coverage in the investigation area decreased by about 5% between 1962 and 2005, with the highest retreat rates occurring between 1992 and 2001. The debris coverage increased concomitantly with the decrease in total glacier area. The clean-ice area decreased by &gt;10%. Digital terrain model (DTM) generation from the early Corona KH-4 stereo data in this high-relief terrain is time-consuming, and the results still contain some elevation errors. However, these are minor in the snow-free areas with gentle slopes. Thus comparison of the surfaces of the debris-covered glacier tongues based on the Corona DTM and an ASTER DTM is feasible and shows the downwasting of the debris-covered glaciers. The highest downwasting rates, more than 20 m (&gt;0.5 m a−1), can be found near the transition zone between the active and the stagnant glacier parts of the debris-covered glacier tongues. The downwasting is lower, but still evident, in the active ice areas and at the snout with thick debris cover. All investigated debris-covered glaciers in the study area show similar behaviour. The estimated volume loss for the investigated debris-covered glacier tongues is 0.19 km3.

Estimating volume change of mountain glaciers using SRTM and map-based topographic data

This paper describes a method for estimating the volume change of mountain glaciers using the Shuttle Radar Topography Mission (SRTM) C-band data (2000) and a digital elevation model (DEM) generated from topographic maps. This approach was developed with SRTM data and topographic maps of 1 : 25 000 scale (1977) from the Akshiirak glaciers (Tien Shan, Central Asia). The DEM for 1977 was generated using 10-m contour lines from 18 map sheets covering the Akshiirak massif and surrounding area. The nominal vertical accuracy of the maps is 3.3 m. The standard deviation of the differences between the map-derived DEM and the SRTM data on glacier-free areas of less than 25deg is 6.3 m. A single localized region in the western periphery of the study area with systematic error in the SRTM data from -20 to 12 m on a 30-km spatial scale was found and excluded from the error analysis. Assuming a 10-m map error on the upper snow-covered glacier areas, the estimated root-mean-square error of the glacier surface change is 8.2 m. From 1977 to 1999, the average glacier surface thinning is 15.1 m, and the estimated volume loss is 6.15 km3. The rate of the Akshiirak glacier volume loss has increased by 2.7 times, compared with historical data from 1943 to 1977. The SRTM data show an opportunity for quantifying climatic and dynamic surface elevation changes in mountain glaciers. Ice, Cloud, and land Elevation Satellite (ICESat) laser altimetry and SRTM data could also be used for the estimation of short-term surface changes of mountain glaciers

R‐wave Amplitude in Lead II of an Electrocardiograph Correlates with Central Hypovolemia in Human Beings

Previous animal and human experiments have suggested that reduction in central blood volume either increases or decreases the amplitude of R waves in various electrocardiograph (ECG) leads depending on underlying pathophysiology. In this investigation, we used graded central hypovolemia in adult volunteer subjects to test the hypothesis that moderate reductions in central blood volume increases R-wave amplitude in lead II of an ECG. A four-lead ECG tracing, heart rate (HR), estimated stroke volume (SV), systolic blood pressure, diastolic blood pressure, and mean arterial pressure were measured during baseline supine rest and during progressive reductions of central blood volume to an estimated volume loss of >1,000 mL with application of lower-body negative pressure (LBNP) in 13 healthy human volunteer subjects. Lower-body negative pressure resulted in a significant progressive reduction in central blood volume, as indicated by a maximal decrease of 65% in SV and maximal elevation of 56% in HR from baseline to -60 mm Hg LBNP. R-wave amplitude increased (p < 0.0001) linearly with progressive LBNP. The amalgamated correlation (R2) between average stroke volume and average R-wave amplitude at each LBNP stage was -0.989. These results support our hypothesis that reduction of central blood volume in human beings is associated with increased R-wave amplitude in lead II of an ECG.

Glacier change (1958–1998) in the North Cascades National Park Complex, Washington, USA

AbstractThe spatial characteristics for all glaciers in the North Cascades National Park Complex, USA, were estimated in 1958 and again in 1998. The total glacier area in 1958 was 117.3 ± 1.1 km2; by 1998 the glacier area had decreased to 109.1 ± 1.1 km2, a reduction of 8.2 ± 0.1 km2 (7%). Estimated volume loss during the 40 year period was 0.8 ± 0.1 km3 of ice. This volume loss contributes up to 6% of the August–September stream-flow and equals 16% of the August–September precipitation. No significant correlations were found between magnitude of glacier shrinkage and topographic characteristics of elevation, aspect or slope. However, the smaller glaciers lost proportionally more area than the larger glaciers and had a greater variability in fractional change than larger glaciers. Most of the well-studied alpine glaciers are much larger than the population median, so global estimates of glacier shrinkage, based on these well-studied glaciers, probably underestimate the true magnitude of regional glacier change.

Microstructures of co-axially folded vein segments and crenulation cleavage: Evidence for dissolution phenomena in the Chamba Thrust Sheet, western Himalayas

The metasediments in the Chamba region experienced three phases of deformation: DF1, DF2 and DF3.Folded quartz veins are co-folded with the F2 crenulation folds. Their geometric and tectonic significance is studied by microstructures and shortening adjacent to the discrete crenulation cleavage, S2. Microstructures of folded vein segments, their geometric changes and truncation to cleavage (S2) are mainly due to pressure-solution phenomena and the estimated volume loss from reconstructed vein segments range from 16 to 25.5%,which is closely related to volume decrease (26%) calculated from the polydeformed slates of North Wales areas.

Armor Stone Abrasion due to Displacements in Sea Storms

A model to estimate volume loss of armor stones caused by abrasion under wave conditions occurring during a structure’s lifetime is proposed. It accounts only for abrasion caused by stone movements, neglecting the effects of stone breakage, wetting-drying, freezing-thawing cycles, and chemical attack and is based on the assumption of proportionality between abraded volume and abrasion work. The model represents rock resistance to abrasion and to unit size and makes use of empirical relationships providing the average frequency of movement and displacement length of armor units. Wave loading is described with a probabilistic analysis. The present model is discussed in the light of a previous one. The comparison makes possible the estimation of the influence of external agents, other than stone mobility and size, on volume loss.

Three dimensional MRI estimates of brain and spinal cord atrophy in multiple sclerosis

OBJECTIVEThe association between brain atrophy and permanent functional deficits in multiple sclerosis and the temporal relation between atrophy and the clinical disease course have seldom been investigated. This study aims...

Volume loss and metasomatism during cleavage formation in carbonate rocks

Controversy exists regarding the amount of volume loss associated with cleavage development. A combination of geometrical and geochemical techniques provides evidence for contemporaneous passive concentration (volume loss) and metasomatism leading to the formation of cleavage in carbonate lithologies and emphasizes the relationship between observational scales and textural heterogeneity. Comparison of protoliths and weakly- to strongly-cleaved rocks along steep, layer-parallel strain gradients within the Doublespring duplex, Lost River Range, Idaho enables quantitative assessments of geometric transformation and elemental mass transfer accompanying progressive deformation. Geometric finite strain analysis documents shortening in the Z direction at low strains ( ε̄ s<0.15) and in both the Z and Y directions at higher strains ( ε̄ s>0.15). Unbalanced shortening in Z and Y with extension in X results in volume loss. Geometrically derived volume strain estimates at the 1–4 cm 3 scale indicate volumetric dilations of from −2% to −12% in uncleaved to weakly-cleaved rocks, and from −20% to −50% in strongly- to very strongly-cleaved rocks. Small-scale significant volume losses and gains contrast with the estimated volume loss of <3% associated with duplex formation at the 100 km 3–1 km 3 scale due to the localization of strain within thin deformation zones. Sampling scale is also a factor in evaluating the major and trace element and O and C isotope compositions of the variably deformed rocks. Samples collected at the 4–15 cm 3 scale reflect mixtures of chemically and mineralogically distinct selvage and microlithon domains. Microdrilling of samples at scales of a few cubic millimeters to 1 cm 3 affords examination of chemical and isotopic differences among individual selvages and microlithons. The data for microdrilled samples demonstrate depletion of Ca and 18O and enrichment of K, Al, Si, Ti, Fe, Na, Mg and P in selvages relative to microlithons and nearby undeformed carbonate layers. The enrichments of some elements (Mg, P, Na and possibly Fe) are more compatible with a passive concentration mechanism, whereas the concentrations of other elements, particularly K, Al, Si and Ti, require significant metasomatic addition during deformation. Shifts in O-isotope compositions of deformed samples relative to the protolith δ 18O values unequivocally demonstrate open-system behavior during deformation. Trends of deformed samples toward lower δ 18O with increasing strain and the δ 18O values of veins are compatible with infiltration by H 2O-rich fluids with relatively low δ 18O V-SMOW (near 0‰). The formation of disjunctive cleavage at the Doublespring duplex occurred by passive concentration resulting from calcite dissolution and related volume loss, and neo-crystallization of illite+kaolinite+quartz±anatase in selvages as a result of metasomatic additions. Chemical and geometric strain softening within selvages likely led to enhanced and preferential fluid flow in selvages.

Chemical changes and fluid-rock interaction in faults of crystalline thrust sheets, northwestern Wyoming, U.S.A.

We investigate the degree of fluid-rock interaction in two thrust faults which formed at 4–7 km and 10–12 km depth in crystalline thrust sheets in northwestern Wyoming using whole-rock geochemistry. The fault zones consist of undeformed and unaltered protolith which bounds damaged zones with increased fracture, fault and vein density and chemical alteration, and a fault core comprised of zones of gouge, cataclasite and ultracataclasite. Whole-rock geochemical analyses of major, minor and trace elements in 26 samples document the fluid-rock interactions in the fault zones. Fault-related rocks from the shallow East Fork fault exhibit 10–40% depletion of Si, Al, K, Na and Ca as measured against immobile Ti as reference in the damaged zone, 40–60% depletion of Ca and Na, and 0–20% depletion of Si, Al and K in the fault core. Rocks from the deeper level White Rock thrust exhibit 10–30% depletion of these elements in protocataclasites at the edge of the fault core and up to 65% depletion in the cataclasites and ultracataclasites of the fault core. We interpret these results to show that soluble elements were removed from the fault zones by syntectonic fluid flow. Estimated volume losses in the shallow fault range from 0 to 22%, whereas the deeper level fault experienced 50–65% volume loss in the fault core. Silica loss is used to estimate fluid-rock ratios in the fault zones by assuming a range of temperatures and silica solubilities in the faults during deformation. Volumetric F/R ratios range from 10 2-10 4 for both faults, which yield fluid fluxes in the fault zones of 10 −6-10 −9 m s −1 using geologic constraints on the life and geometry of the fault. Depletion and volume loss at deep levels was greater due to hotter fluids and finer grain-size generated by mixed brittle-plastic deformation, whereas at shallow levels, cooler temperatures and purely brittle deformation resulted in vein formation and less chemical fluid-rock interaction.

Evaluation of a Roadside Survey Procedure for Dwarf Mistletoe on Ponderosa Pine in Colorado

Tentative study areas were randomly Merrill, L. M., Hawksworth, F. G., and Johnson, D. W. 1985. Evaluation of a roadside survey chosen on the basis of the amount of procedure for dwarf mistletoe on ponderosa pine in Colorado. Plant Disease 69:572-573. dwarf mistletoe infection observed. A survey of dwarf mistletoe intensity on ponderosa pine (Pinusponderosa) was conducted along Presence or absence of dwarf mistl roadsides and on adjacent plots in the Roosevelt, Pike, and San Juan national forests in Colorado. was recorded for each 0.1 km of a strip Presence of dwarf mistletoe (Arceuthobium vaginatum subsp. cryptopodum) was recorded along one chain (20 m) wide and 1.6 km long on roads for each 0. 1 km of a strip one chain (20 m) wide and 1.6km long. Plots were then established the right side of the road in each study at 100-m intervals 40 m from and parallel to the same surveyed portion of the road. Regression of area. The study areas were grouped into plot data on roadside data was highly significant (R 2 = 0.88 for all national forests combined). The incidence categories by visual estimation roadside survey procedure can be reliable for estimating the proportion of ponderosa pine stands of the percentage of ponderosa pine with dwarf mistletoe if the road network provides a representative sample of the stands being infested with dwarf mistletoe: 1) none r surveyed. no visible infection, 2) low = fewer than one-third of the trees infected, 3) medium = one-third to two-thirds of the trees Dwarf mistletoes (Arceuthobium spp.) compared with results obtained from infected, and 4) high = more than twoare highly specialized, dicotyledonous more intensive surveys. Hawksworth (6) thirds of the trees infected. pathogens that damage many North found that incidence estimated from a Thirty-five study areas were estabAmerican conifers, including ponderosa roadside survey of ponderosa pine on the lished: three study areas in each dw pine (Pinus ponderosa Laws.). South- Mescalero Apache Reservation (New mistletoe incidence category in each of western dwarf mistletoe (Arceuthobium Mexico) was within 5% of that estimated the three national forests. (Only vaginatum (Willd.) Presl. subsp. crypto- from an intensive plot survey (9). Data study areas in the high-incidence category podum (Engelm.) Hawksw. & Wiens) is from an earlier roadside survey of were established in the San Juan National distributed throughout the central Rocky lodgepole pine (P. contorta Dougl.) Forest.) Within each study area, a row of Mountains and the Southwest (8). The conducted by Hawksworth in 1958 (7) plots (on the surveyed side of the road) pathogen causes extensive losses in were compared with those from a 1977 was established at 100-m intervals 40 m ponderosa pine stands through growth roadside/plot survey conducted by from and parallel to the road. At each reduction, mortality, tree deformity, and Johnson et al (10) in the Medicine Bow plot center, a fixed 0.004-ha circular plot reduction in cone and seed crops (13). National Forest in Wyoming. Estimates and a variable plot (basal area factor 2.3 Dwarf mistletoe also weakens its host, of incidence were 59% in 1958 and 60.5% m 2 /ha.) were established. Depending on increasing susceptibility to other pests in 1977. In addition, there was only 0.5% the curvature of the road, 13-17 plots (8). Information on dwarf mistletoe difference between the incidence observed intensity and distribution and estimates from the roadside (60.5%) and that wer loated infestudy area. of losses caused by dwarf mistletoes are observed in plots (60%) in the 1977 infected tree was present. Litne needed to assist the land manager in survey. Although the roadside survey regression analyses of the data were used making sound management decisions (2). technique is reliable where the forest type to compare the incidence of dwarf Dwarf mistletoe surveys have routinely is relatively continuous, the accuracy of combined plot survey information, this technique in discontinuous forest found in the plots 40 m from the road. designed to estimate volume loss, with types (i.e., ponderosa pine) was unknown. Data from each national forest were roadside reconnaissance surveys to Thus, this study was made to evaluate the analyzed separately. Data were also determine incidence and severity of the accuracy of roadside surveys for gopdacrigt h wr iteo