Tree Age Data Research Articles

Japanese Oak Wilt Disease decreased survival probability and mean lifetime of tree populations in a secondary natural forest

ABSTRACT The purpose of this study was to assess the effects of Japanese Oak Wilt Disease on mortality in a tree population. The study site was the permanent plot of 0.26 ha established in the secondary forest dominated by Abies firma, Tsuga sieboldii and Quercus serrata at the University of Tokyo Chiba Forest in the southeastern part of the Boso peninsula, Japan. We set the two observation periods of 1999–2008 and 2009–2021, and Japanese Oak Wilt Disease invaded the study site in the middle of the second period. We collected tree age data for both alive and dead trees in the two periods based on semi-nondestructive drilling measurements for trees using a RESISTOGRAPH. Survival analyses were conducted on the second-period data, and the demographic metrics such as mortality ratios and mean lifetimes were compared between the two periods. The results showed that: the mortality ratio of the tree population at old ages, where oaks (Quercus serrata) concentrated in their age distribution, significantly increased; the effect of the oak group was significant on mortality in the tree population; the hazard for the oak group was 24 times the hazard for the other tree species group; the survival curve reflected the mass mortality in oaks at old ages, which led to the decrease of mean lifetime less than half. Consequently, it was implied that the effects of Japanese Oak Wilt Disease impacted the demographic metrics of oak trees.

Age and spatial distribution of the world's oldest trees.

Extremely old trees have important roles in providing insights about historical climatic events and supporting cultural values. Yet there has been limited work on the global distribution and conservation of these trees. We extracted information on 197,855 tree cores at 4,854 sites, and combined it with other tree age data from a further 156 sites, to determine the age of the world's oldest trees and quantify the factors influencing their global distribution. We found that extremely old trees >1,000 years are rare. Among 30 individual trees that exceeded 2,000 years old, 27 occurred in high mountains. Our model suggests that many of the existing oldest trees occur in high-elevation, cold and arid mountains with limited human disturbance. This pattern is markedly different from that of the tallest trees, which are more likely to occur in more mesic and productive locations. Global warming and expansion of human activities may induce rapid population declines of extremely old trees. New strategies, including targeted establishment of conservation reserves in remote regions, especially those in western Table 1 parts of China and USA, are required to protect these trees. This article is protected by copyright. All rights reserved.

Age-Based Survival Analysis of Coniferous and Broad-Leaved Trees: A Case Study of Preserved Forests in Northern Japan

Scientifically sound methods are essential to estimate the survival of trees, as they can substantially support sustainable management of natural forest resources. Tree mortality assessments have mainly been based on forest inventories and are mostly limited to planted forests; few studies have conducted age-based survival analyses in natural forests. We performed survival analyses of individual tree populations in natural forest stands to evaluate differences in the survival of two coniferous species (Abies sachalinensis (F. Schmidt) Mast. and Picea jezoensis var. microsperma) and all broad-leaved species. We used tree rings and census data from four preserved permanent plots in pan-mixed and sub-boreal natural forests obtained over 30 years (1989–2019). All living trees (diameter at breast height ≥ 5 cm in 1989) were targeted to identify tree ages using a Resistograph. Periodical tree age data, for a 10-year age class, were obtained during three consecutive observation periods. Mortality and recruitment changes were recorded to analyze multi-temporal age distributions and mean lifetimes. Non-parametric survival analyses revealed a multi-modal age distribution and exponential shapes. There were no significant differences among survival probabilities of species in different periods, except for broad-leaved species, which had longer mean lifetimes in each period than coniferous species. The estimated practical mean lifetime and diameter at breast height values of each coniferous and broad-leaved tree can be applied as an early identification system for trees likely to die to facilitate the Stand-based Silvicultural Management System of the University of Tokyo Hokkaido Forest. However, the survival probabilities estimated in this study should be used carefully in long-term forest dynamic predictions because the analysis did not include the effects of catastrophic disturbances, which might significantly influence forests. The mortality patterns and survival probabilities reported in this study are valuable for understanding the stand dynamics of natural forests associated with the mortality of individual tree populations.

Age-independent site index mapping with repeated single-tree airborne laser scanning

ABSTRACTA novel method for age-independent site index estimation is demonstrated using repeated single-tree airborne laser scanning (ALS) data. A spruce-dominated study area of 114 km2 in southern Norway was covered by single-tree ALS twice, i.e. in 2008 and 2014. We identified top height trees wall-to-wall, and for each of them we derived based on the two heights and the 6-year period length. We reconstructed past, annual height growth in a field campaign on 31 sample trees, and this showed good correspondence with ALS based heights. We found a considerable increase in site index, i.e. about 5 m in the H40 system, from the old site index values. This increase corresponded to a productivity increase of 62%. This increase appeared to mainly represent a real temporal trend caused by changing growing conditions. In addition, the increase could partly result from underestimation in old site index values. The method has the advantages of not requiring tree-age data, of representing current growing conditions, and as well that it is a cost-effective method with wall-to-wall coverage. In slow-growing forests and short time periods, the method is least reliable due to possible systematic differences in canopy penetration between repeated ALS scans.

Spatial interpolation and mean fire interval analyses quantify historical mixed-severity fire regimes

Tree-age data in combination with fire scars improved inverse-distance-weighted spatial modelling of historical fire boundaries and intervals for the Darkwoods, British Columbia, Canada. Fire-scarred trees provided direct evidence of fire. The presence of fire-sensitive trees at sites with no fire scars indicated fire-free periods over their lifespan. Sensitivity analyses showed: (1) tree ages used in combination with fire-scar dates refined fire boundaries without biasing mean fire return intervals; and (2) compared with derived conservative, moderate and liberal thresholds (i.e. minimum burn likelihood cut-off values), fixed thresholds generated area burned estimates that were most consistent with estimates based on the proportion of plots that recorded historical fires. Unweighted and weighted spatial mean fire intervals (50–56 and 58–68 years respectively) exceeded dendrochronological plot-level (38-year) estimates based on fire scars only. Including tree-age data from fire-sensitive trees to calculate landscape-level fire interval metrics lengthened the mean return intervals, better representing historical high-severity fires. Supplementing fire scars with tree ages better reflects the spatiotemporal diversity of fire frequencies and severities inherent to mixed-severity fire regimes.

Forest dynamics and climate sensitivity of an endangered Carolina hemlock community in the southern Appalachian Mountains, USA

During the last century, the eastern United States has functionally lost two major tree species (American chestnut and American elm), two more, eastern and Carolina hemlock, will likely be functionally extinct during much of their ranges by 2050. Carolina hemlock forests are geographically limited to high elevations in the southern Appalachian Mountains and are considered to be endangered. We collected forest stand, composition, and tree age data at the beginning of a hemlock woolly adelgid (HWA) infestation. Prior to the arrival of HWA, Carolina hemlocks were healthy and densely populated in the overstory and understory. While Carolina hemlock regenerated successfully and continuously from 1850 to 2010, the development of this Carolina hemlock forest will be altered by the HWA and may result in an increase in the density of northern red oak, white oak, mountain laurel, and Catawba rhododendron. Carolina hemlocks prefer cool, wet summers with older trees experiencing greater reductions in radial growth than younger trees during droughts. This study demonstrates that dendrochronological techniques can provide critical annual information on Carolina hemlock forest development and tree age–climate response. Our results provide a multicentury perspective for conservation efforts and management of Carolina hemlock forests in the southern Appalachian Mountains.

Historical high-severity fire patches in mixed-conifer forests

Two ends of the fire regime spectrum are a frequent low-intensity fire regime and an infrequent high-intensity fire regime, but intermediate fire regimes combine high- and low-severity fire over space and time. We used fire-scar and tree-age data to reconstruct fire regime attributes of mixed-conifer and aspen forests in the North Rim area of Grand Canyon National Park, with a goal of estimating patch sizes of historical high-severity fire and comparing them with modern patch sizes. We used three methods based on (i) aspen groves, (ii) even-aged stands, and (iii) inverse distance weighting, to estimate occurrence and patch sizes of historical high-severity fire. Evidence of high-severity fire was common in the 1800s, and high-severity fire years were associated with drought. High-severity fire patch sizes likely ranged from 10−1 to 102 ha. However, the forest is quite young, and we cannot rule out a historical large high-severity fire that could have reinitiated much of the 1400 ha study area. Fire scars, which are indicative of low-severity fire, were also common. Historical fire was likely heterogeneous across the landscape. Maintaining heterogeneity of fire severity, size, and frequency would promote heterogeneity of forest structure and composition and resilience to future disturbances.

Applying age-based mortality analysis to a natural forest stand in Japan

Mortality analysis of tree populations is widely applied to forest science studies. When mortality analysis is applied to forest inventories, the use of the variable of tree age is not common due to the difficulty of measuring age data censored in successive observations. The purpose of this study is to apply age-based mortality analysis, i.e., survival analysis, to the individual tree populations in a natural forest. The study site was the secondary natural stand of 0.26 ha dominated by fir (Abies firma), hemlock (Tsuga sieboldii), and oak (Quercus serrata) in the Boso peninsula, Japan. First, we measured the ages of the trees with diameter at breast height greater than or equal to 5 cm using a RESISTOGRAPH. Then, tree mortality probabilities of both non-parametric Kaplan–Meier estimates and parametric probability distributions of Gamma and Weibull were estimated by applying survival analysis techniques to the tree age data. The results implied that the survival analyses could be implemented not only by the non-parametric estimates in any cases but also by the common parametric distributions of Gamma and Weibull in cases in which the tree mortality probability distribution had a monotonously decreasing shape as observed in the immature natural stand in the study site.

A 40-Year Record of Tree Establishment Following Chaining and Prescribed Fire Treatments in Singleleaf Pinyon (Pinus monophylla) and Utah Juniper (Juniperus osteosperma) Woodlands

Chaining and prescribed fire treatments have been widely applied throughout pinyon–juniper woodlands of the western United States in an effort to reduce tree cover and stimulate understory growth. Our objective was to quantify effects of treatment on woodland recovery rate and structure and the relative dominance of the two major tree species in our Great Basin study area, singleleaf pinyon (Pinus monophylla Torr. & Frém.) and Utah juniper (Juniperus osteosperma [Torr.] Little). We resampled plots after a 40-yr interval to evaluate species-specific differences in tree survivorship and establishment from posttreatment age structures. Tree age data were collected in 2008 within four chained sites in eastern Nevada, treated in 1958, 1962, 1968, and 1969 and originally sampled in 1971. The same data were collected at five prescribed burn sites treated in 1975 and originally sampled in 1976. All chained sites had greater juniper survival than pinyon survival immediately following treatment. Chained sites with higher tree survival also had the greatest amount of new tree establishment. During the interval between treatment and the 2008 sampling, approximately four more trees per hectare per year established following chaining than following fire. Postfire tree establishment only occurred for the initial 15 yr and was dominated by juniper. Establishment after chaining was dominated by juniper for the first 15 yr but by pinyon for 15–40 yr following treatment. Results support an earlier successional role for juniper than for pinyon, which is more dependent upon favorable microsites and facilitation from nurse shrubs. Repeated chaining at short intervals, or prescribed burning at infrequent intervals, will likely favor juniper dominance. Chaining at infrequent intervals (> 20–40 yr) will likely result in regained dominance of pinyon. Chaining treatments can be rapidly recolonized by trees and have the potential to create or amplify landscape-level shifts in tree species composition.

Human influences on fire regimes and forest structure in the Chihuahuan Desert Borderlands

Recent research in isolated sites in southwestern North America suggests that spatial variation in land use history can result in differences in the dates of fire exclusion onset and the extent to which forests have changed in response to fire cessation. We investigated the relationships among fire, land use, and forest structure in three mountain ranges that straddle the Texas–Mexico border including The Davis Mountains Preserve of The Nature Conservancy and Big Bend National Park in west Texas, and The Maderas del Carmen Protected Area in northern Coahuila, Mexico. We quantified fire regime characteristics (frequency, size, severity, and seasonality) and forest stand structure using dendroecology. Frequent low severity fire was a dominant force shaping forest structure and species composition historically. Mean fire return intervals prior to fire exclusion (1700–1900) ranged from 1 to 29years for fires scarring >25% of the fire-scar samples. The per-sample fire return intervals ranged from 15 to 25years signifying historically frequent fires at any one location on the landscape. The contemporary period was characterized by a doubling of fire return intervals across all three sites, probably as a result of fire exclusion through livestock (sheep) grazing. The presence of older trees in the tree age data suggested that fires were predominantly low in severity and that tree regeneration occurred during fire free intervals. Our results show that the disruption of frequent, low severity fire regimes in our sites resulted in widespread tree regeneration. This study documents the importance of sheep grazing as a causal factor of fire exclusion in west Texas and northern Mexico, which occurred in the early to mid-1900s, well after the 1880s cattle boom.

108 years of change in spatial pattern following selective harvest of a Pinus ponderosa stand in northern Arizona, USA

AbstractQuestions: How did an initial tree harvest in 1894 influence the spatial and temporal patterns of Pinus ponderosa recruitment? How do these patterns compare to our understanding of P. ponderosa stand dynamics prior to Euro‐American settlement? How might spatial pattern information, particularly with respect to patch characteristics, inform current restoration and management practices?Location: A 2.59‐ha permanent sample plot in the Fort Valley Experimental Forest, Flagstaff, Arizona. The plot was selectively harvested in 1894 and measured in 1909 and 2002.Methods: We used historical stem‐map and ledger data, contemporary data, and dendrochronological techniques to reconstruct stand structure (tree size, age, location) in three scenarios: (1) unharvested (1909), (2) harvested (1909), and (3) contemporary (2002). We used Clark and Evans' R, Ripley's K(t) univariate analysis, and correlogram analysis to assess the spatial pattern in each scenario. We also used Ripley's K12(t) bivariate analysis and tree age data to examine spatial and temporal recruitment patterns as observed in the contemporary scenario.Results and Conclusions: The unharvested stand was aggregated at scales up to 28 m. The selective harvest accentuated the spatial patchiness of the stand in 1909 and changed spatial patterns by homogenizing tree size within patches. By 2002, the stand was a single patch dominated by small trees. Post‐harvest recruitment patterns were not spatially random; Pinus seedlings initially established in natural grass openings and then proceeded to fill‐in stump patches created by harvesting. Knowledge of spatial pattern should be explicitly incorporated into restoration activities in these forests.

Cost of preventing variceal rebleeding with transjugular intrahepatic portal systemic shunt and distal splenorenal shunt

We examined the cost and cost effectiveness of distal splenorenal shunt (DSRS) and transjugular intrahepatic portosystemic shunt (TIPS) in the prevention of variceal rebleeding. Patients participated in a randomized controlled trial comparing DSRS to TIPS. Quality of life (QOL) was measured using SF-36 preceding randomization and yearly thereafter. Cost utility analysis was performed using TreeAge DATA. Costs for both in- and out-patient events and interventions were obtained for each patient. Costs using coated stents were estimated using different rates of stenosis. Incremental cost effectiveness ratios (ICERs) were determined at 1, 3 and 5 years. The average yearly costs of managing patients after TIPS and DSRS over 5 years were similar, $16,363 and $13,492, respectively. Cost of TIPS for surviving patients exceeded the cost of DSRS at years 3 and 5 but not significantly. ICERs per life saved favored TIPS at year 5 ($61,000). If coated rather than bare stents were used the cost effectiveness of TIPS increased slightly. TIPS is as effective as DSRS in preventing variceal rebleeding and may be more cost effective. TIPS, in all aspects, is equal to DSRS in the prevention of variceal rebleeding in patients who are medical failures.

Cost Analysis of Temporarily Placed Covered Self Expandable Metallic Stents Versus Plastic Stents in Biliary Strictures Related to Chronic Pancreatitis

Background and Aims: Benign biliary strictures secondary to chronic pancreatitis (CP) are traditionally managed by ERCP with plastic stents insertion. Their potential to occlude and migrate makes them only temporarily efficacious and has led many to consider other options. Temporary placement of CSEMS might offer an alternative in terms of reducing the number of sessions required, but the higher cost associated of CSEMS may be a concern. This study prospectively compared a group of patients treated by CSEMS to a group of patients who received plastic stents and performed a cost analysis to evaluate the overall cost of each modality. Methods: 22 patients with biliary strictures related to CP underwent CSEMS placement (Wallstent, Boston Scientific), and were compared to a set of 27 patients who received plastic stents with 22 of them matched to the CSEMS group by age (51 ± 12 y/o and 52 ± 13 respectively, p = 0.67) gender (20 and 17 male in each group, p = 0.227) and etiology of chronic pancreatitis (15 and 16 alcohol related in each group, p = 0.748). CSEMS were left in place until adequate biliary drainage was achieved, confirmed by clinical improvement, normalization of liver function tests and imaging before removal was effected with snare or rat tooth . Plastic stents were replaced every three months until resolution of stricture. All procedures were performed by 2 dedicated pancreatico-biliary endoscopists (PY and MK). Response to therapy, morbidity, and overall outcome were determined. A cost analysis was performed using decision analysis software (Treeage Data 3.5). Results: 19 patients in the CSEMS group (86%) responded to treatment versus 18 (82%) in the plastic stent group. CSEMS and plastic stents were left in place for a median time of 5 (range: 1-21) versus 8 months (range: 3-35). Median number of session required until resolution of stricture was respectively 2 (range: 1-3) versus 5 (range: 2-12) (p = 0.0001). Complications in the CSEMS group included migration without stricture resolution (1), post sphincterotomy bleed (1), pain (1) and worsening pancreatitis with infected pseudocyst (1). One patient spontaneously passed CSEMS with resolution of the stricture. In this model, the total cost using plastic stents was $17,304.92 per patient. Total cost for CSEMS was $10,137.22. The total cost savings using CSEMS was $7,167.70 per patient. Conclusion: The use of CSEMS in benign biliary strictures related to CP provides substantial cost savings compared to conventional ERCP with plastic stenting. The fewer number of sessions required to achieve resolution of stricture using CSEMS compensates for the initial higher cost of CSEMS placement.

Cost-effectiveness and long-term impact of Helicobacter pylori 'test and treat' service in reducing open access endoscopy referrals.

We have shown that the introduction of a carbon urea breath test (13C-UBT) service for Helicobacter pylori screening and eradication is effective in reducing the rate of open access endoscopy referrals in patients aged < 40 years in the short term. This has been substantiated by several randomized controlled trials comparing a 'test and treat' strategy with early endoscopy in these patients. However, the long-term impact of such a strategy is not established. To ascertain the influence of 13C-UBT services on open access endoscopy referral rates in dyspeptic patients under the age of 40 years over a period of 5 years. Retrospective analysis of open access endoscopy referral rates between August 1990 and July 2000. Cost minimization analysis was performed with a Decision Analysis Model using Treeage Data 3.5. The total number of open access referrals for endoscopy during 1990-1995 was between 765 and 1325 per year. The proportion of endoscopies performed in patients < 40 years ranged between 33.4% and 34.6%. The total number of endoscopy referrals during 1995-2000 after the introduction of the 13C-UBT services was between 1178 and 1321 per year. However, there was a sustained reduction in the proportion of patients aged < 40 years, ranging between 23.2% and 26.2% (Chi2 = 153.9, degrees of freedom = 9, P < 0.0001) during this period. The H. pylori screening and treatment strategy using the 13C-UBT service results in a sustained reduction of the number of endoscopy referrals and is cost effective in dyspeptic patients under the age of 40 years, enabling better utilization of available resources.

Floodplain and regional scale variation in earthquake effects on forests, Westland, New Zealand

Using existing and new tree age data, we assess spatial variation in earthquake effects in Westland at regional and floodplain scales. In Westland there have been four major episodes of forest cohort establishment, three of which appear to relate to Alpine Fault earthquakes in ad c. 1460, 1610–1620, and 1717, and the fourth of which coincides with a Fiordland earthquake in ad 1826. The ad 1826 event had its greatest effect in south Westland. In contrast, the impacts of the ad 1610–1620 and 1717 earthquakes were more extensive, with forest cohort initiation following both events occurring throughout Westland. However, these two events differed in their effects at the floodplain scale, with the ad 1610–1620 event triggering a larger aggradation event on floodplains than the ad 1717 event. Variation in earthquake effects at a regional scale most likely reflects variation in earthquake magnitude and the location of the epicentre. At a floodplain scale, variation in effect could reflect differences in both earthquake magnitude and shaking and the amount of sediment stored in upland catchments as a consequence of the time elapsed since the last event.

Assessing fire regimes on Grand Canyon landscapes with fire-scar and fire-record data

Fire regimes were reconstructed from fire-scarred trees on five large forested study sites (135–810 ha) on the North and South Rims at Grand Canyon National Park. Adequacy of sampling was tested with cumulative sample curves, effectiveness of fire recording on individual trees, tree age data, and the occurrence of 20th Century fires which permitted comparison of fire-scar data with fire-record data, a form of modern calibration for the interpretation of fire-scar results. Fire scars identified all 13 recorded fires &gt;8 ha on the study sites since 1924, when record keeping started. Records of fire season and size corresponded well with fire-scar data. We concluded that the sampling and analysis methods were appropriate and accurate for this area, in contrast to the suggestion that these methods are highly uncertain in ponderosa pine forests. Prior to 1880, fires were most frequent on low-elevation ‘islands’ of ponderosa pine forest formed by plateaus or points (Weibull Median Probability Intervals [WMPI] 3.0–3.9 years for all fires, 6.3–8.6 years for ‘large’ fires scarring 25% or more of the sampled trees). Fires were less frequent on a higher-elevation ‘mainland’ site located further to the interior of the North Rim (WMPI 5.1 years all fires, 8.7 years large fires), but fires tended to occur in relatively drier years and individual fires were more likely to burn larger portions of the study site. In contrast to the North Rim pattern of declining fire frequency with elevation, a low-elevation ‘mainland’ site on the South Rim had the longest fire-free intervals prior to European settlement (WMPI 6.5 years all fires, 8.9 years large fires). As in much of western North America, surface fire regimes were interrupted around European settlement, 1879 on the North Rim and 1887 on the South Rim. However, either two or three large surface fires have burned across each of the geographically remote point and plateau study sites of the western North Rim since settlement. To some extent, these sites may be rare representatives of nearly-natural conditions due to the relatively undisrupted fire regimes in a never-harvested forest setting.

Using tree recruitment patterns and fire history to guide restoration of an unlogged ponderosa pine/Douglas-fir landscape in the southern Rocky Mountains after a century of fire suppression

Summary Tree age and fire history were studied in an unlogged ponderosa pine/Douglas-fir (Pinus ponderosa/Pseudotsuga menziesii) landscape in the Colorado Front Range mountains. These data were analysed to understand tree survival during fire and post-fire recruitment patterns after fire, as a basis for understanding the characteristics of, and restoration needs for, an ecologically sustainable landscape. Comparisons of two independent tree age data sets indicated that sampling what subjectively appear to be the five oldest trees in a forest polygon could identify the oldest tree. Comparisons of the ages of the oldest trees in each data set with maps of fire history suggested that delays in establishment of trees, after stand-replacing fire, ranged from a few years to more than a century. These data indicate that variable fire severity, including patches of stand replacement, and variable temporal patterns of tree recruitment into openings after fire were major causes of spatial heterogeneity of patch structure in the landscape. These effects suggest that restoring current dense and homogeneous ponderosa pine forests to an ecologically sustainable and dynamic condition should reflect the roles of fires and variable patterns of tree recruitment in regulating landscape structure.

Growth and yield of some indigenous trees in an Amazonian agroforestry system: A rural-history-based analysis

Over the years farmers of Japanese descent in the Brazilian Amazon have planted indigenous trees that yield various products and services: fruit, seeds,bark, latex, oil, and shade and wind breaks for understory crop plants. Production of timber is often the intended end use of such planted trees. Long-term growth performance of these trees nevertheless has not been well documented. The authors constructed 65-year growth curves for nine indigenous tree species based on measurements of diameter at breast height (dbh), height, and tree age data provided by farmers in the Brazilian State of Para. An index of wood prices used to calculate state stumpage taxes was then applied to mean stem wood growth curves to produce price curves. These price curves estimate both present value of standing timber, and the value added from annual growth of standing timber in the agroforestry systems studied. The results of this study provide local farmers with a tool to estimate potential annual income from the growth of their trees, and a basis for planning timber harvest rotations. This study's approach may be applicable in other parts of the tropics, where growth information about indigenous trees commonly used in agroforestry is lacking.

4582 Cost-effectiveness of endoscopic ultrasonography in upper gi submucosal tumors: a prospective multicenter study of the german eus-club.

Background: A large number of studies have dealt with the accuracy of endoscopic ultrasonography (EUS) in upper GI submucosal lesions (SML). We aimed at determining the potential influence of EUS on the further management of these lesions and its cost-effectiveness. Methods: In a prospective multicenter study (23 German centers) patients with the suspicion of a SML underwent endoscopy and EUS. Referring physicians were asked about the further management withoutEUS (without knowledge of EUS results at this time). After obtaining EUS results, they were asked again about their further diagnostic and/or therapeutic approach in the patients, complemented by a 6 month follow-up. These data were then used for a cost-minimization analysis, the endpoint of which was the establishment of the final diagnosis. The frequency of each diagnostic step in the study population was taken for its probability of occurence. For both strategies (with/without EUS) the used ressources and the net costs of a representative hospital were calculated for Germany and the USA (Germany: EUS 148 $, CT 241 $, endoscopy 79 $; USA EUS: 338 $, CT: 205 $, endoscopy 162 $). Data were analyzed using Tree Age Data 3.5. Results were validated with a sensitivity analysis. Results: Final diagnoses: 102 SML, of those 84 tumors (SMT), 18 other lesions, and 48 extraluminal compressions (ELC), mostly by normal structures/ organs. EUS reduced the rate of further diagnostic tests from 93% to 47%, whereby 2 tests were replaced in 38% and 1 test in 72%. 97% of all CTs, 70% of all endoscopic controls and 64% of all large particle biopsies (LPB) were replaced by EUS. In 9 of 10 ELC cases LBP was not performed after EUS; some cases were due to compression by vessels or by the spleen, which would have led to potentially severe complications. For the cost minimzation analysis however, costs of complications were not considered. The costs of the EUS strategy based on German hospital costs, were 207 $/pt., the costs of the strategy without EUS 265 $, these differences being preserved after sensitivity analysis. For the US, From an USA hospital perspective, however, these values were 480 $/pt (EUS strategy) and 362 $/pt. (non-EUS strategy). Conclusions: EUS replaces 2/3 of other tests, among those also potentially hazardous procedures. EUS is also cost-effective in the diagnosis of SML in the German health care system; in the USA, where EUS is substantially more expensive than CT, this advantage of the EUS strategy could not be maintained.

Tree invasion within a pine/grassland ecotone: an approach with historic aerial photography and GIS modeling

In previous studies, evidence of tree invasion into grasslands has mainly been through comparison of historical terrestrial photographs and/or tree age data. The goal of this paper is to provide a quantitative description of the tree invasion process at a landscape scale using historical aerial photography, image processing and geographic information systems (GIS) approaches. Various map interpretive techniques provided evidence of shifts in the ponderosa pine-grassland ecotone along the Colorado Front Range since the late 1930s. Historical aerial photos were digitally scanned and the outlines of tree invasions into the grassland were determined based on gray tone density slicing. Image processing of digitized aerial photography identified areas of change in tree cover and quantified locations and total hectares of tree invasions into grassland areas. Overall, the results clearly show an increase in woodland areas where there formerly existed grasslands. GIS modeling was used to relate tree invasion patterns to topographic orientation and changes in settlement patterns. The importance of terrain aspect on rate of tree invasion is clearly shown by the greater rate of tree invasion on north-facing slopes (generally moister with less heat stress) versus south-facing slopes. The most dramatic change in the controls of vegetation patterns over the past one or two centuries has been the decline in fire frequency due to fire suppressing policy since ca. 1920. However, changes in grazing regimes may also have played an important role. When comparing these results to the instrumental climate record of the area, periods of favorable climatic conditions for seedling establishment generally correspond to periods of increased rate of tree invasion into grassland areas.