Within-stand variation in windthrow in southern boreal forests of Minnesota: Is it predictable?

2004 ◽  
Vol 34 (2) ◽  
pp. 365-375 ◽  
Author(s):  
Chris J Peterson
Keyword(s):  
Boreal Forests ◽  
Fall Risk ◽  
Abies Balsamea ◽  
Basal Area ◽  
Test Sample ◽  
Test Portion ◽  
Data Set ◽  
Trunk Diameter ◽  
Regression Parameters ◽  
Standing Trees

Wind damage to forests is determined by numerous factors that interact to produce complex, seemingly random damage patterns. However, the complexity may lie mostly among stands and be less within stands: in this study, I attempted to discern how predictable tree fall risk is within five southern boreal forest stands in northeastern Minnesota. I sampled five stands in the Boundary Waters Canoe Area Wilderness, following a July 1999 catastrophic windstorm. Levels of damage varied from 29.5% to 86.8% of basal area fallen and 23.3% to 63.4% of stems fallen. In all sites, the disturbance reduced mean trunk diameter of standing trees. In general, Abies balsamea (L.) Mill. was the most vulnerable species. I split the data set from each site into predictor and test portions and used the predictor data sets to derive logistic regression parameters for the relationship of tree size (trunk diameter) to probability of tree fall. Models based on these parameters allowed quite accurate predictions of the levels of damage in the test portion of each stand. For the five sites, the proportion of test trees predicted to fall differed from the proportion observed to fall by 5.7%, 3.9%, 8.3%, 1.4%, and 3.7% of the total test sample size. This suggests that while numerous factors indeed influence tree fall risk, the sizes and identities of trees may account for most of the within-stand variation in damage.

scholarly journals Terrestrial Laser Scanning and Ground Truth Data for Characterizing Downed Dead Wood

2020 ◽  
Author(s):  
Tuomas Yrttimaa ◽  
Ninni Saarinen ◽  
Ville Luoma ◽  
Topi Tanhuanpää ◽  
Ville Kankare ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Laser Scanning ◽  
Dead Wood ◽  
Terrestrial Laser Scanning ◽  
Ground Truth ◽  
Point Clouds ◽  
Data Set ◽  
Ground Truth Data ◽  
Standing Trees ◽  
Downed Dead Wood

The feasibility of terrestrial laser scanning (TLS) in characterizing standing trees has been frequently investigated, while less effort has been put in quantifying downed dead wood using TLS. To advance dead wood characterization using TLS, we collected TLS point clouds and downed dead wood information from 20 sample plots (32 m x 32 m in size) located in southern Finland. This data set can be used in developing new algorithms for downed dead wood detection and characterization as well as for understanding spatial patterns of downed dead wood in boreal forests.

scholarly journals Improving prediction of fall risk among nursing home residents using electronic medical records

2015 ◽  
Vol 23 (2) ◽  
pp. 276-282 ◽  
Author(s):  
Allison Marier ◽  
Lauren E.W. Olsho ◽  
William Rhodes ◽  
William D. Spector
Keyword(s):  
Risk Factors ◽  
Nursing Home ◽  
Electronic Medical Records ◽  
Medical Records ◽  
Fall Risk ◽  
Nursing Home Residents ◽  
Additional Risk Factor ◽  
Data Set ◽  
Regression Parameters ◽  
Fall Risk Factors

Abstract Objective Falls are physically and financially costly, but may be preventable with targeted intervention. The Minimum Data Set (MDS) is one potential source of information on fall risk factors among nursing home residents, but its limited breadth and relatively infrequent updates may limit its practical utility. Richer, more frequently updated data from electronic medical records (EMRs) may improve ability to identify individuals at highest risk for falls. Methods The authors applied a repeated events survival model to analyze MDS 3.0 and EMR data for 5129 residents in 13 nursing homes within a single large California chain that uses a centralized EMR system from a leading vendor. Estimated regression parameters were used to project resident fall probability. The authors examined the proportion of observed falls within each projected fall risk decile to assess improvements in predictive power from including EMR data. Results In a model incorporating fall risk factors from the MDS only, 28.6% of observed falls occurred among residents in the highest projected risk decile. In an alternative specification incorporating more frequently updated measures for the same risk factors from the EMR data, 32.3% of observed falls occurred among residents in the highest projected risk decile, a 13% increase over the base MDS-only specification. Conclusions Incorporating EMR data improves ability to identify those at highest risk for falls relative to prediction using MDS data alone. These improvements stem chiefly from the greater frequency with which EMR data are updated, with minimal additional gains from availability of additional risk factor variables.

Application of shadow fraction models for estimating attributes of northern boreal forests

2012 ◽  
Vol 42 (9) ◽  
pp. 1750-1757 ◽  
Author(s):  
Joan E. Luther ◽  
Richard A. Fournier ◽  
Mélanie Houle ◽  
Antoine Leboeuf ◽  
Douglas E. Piercey
Keyword(s):  
Boreal Forests ◽  
Potential Role ◽  
Black Spruce ◽  
Abies Balsamea ◽  
Basal Area ◽  
Deciduous Trees ◽  
Mean Square Errors ◽  
Fraction Method ◽  
Relative Root

A shadow fraction method was developed previously for mapping forest attributes of northern black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) forests. This paper evaluates application of the method for (i) balsam fir stands ( Abies balsamea (L.) Mill.), (ii) stands with higher volume and biomass than those of previous studies, and (iii) stands with a higher composition of deciduous trees and steeper slopes. Models developed for new test sites in (i) central Labrador and (ii) western Newfoundland were not statistically different from previous models for biomass, volume, and basal area. Relative root mean square errors (RMSEr) for central Labrador were slightly lower than those found in other test sites (RMSEr: 24%–29%) but higher for western Newfoundland (RMSEr = 37%–43%), attributed to the higher upper limit of measured attributes and increased presence of deciduous trees. Results suggest that reasonable estimates can be generated for conifer forests of northeastern Canada; however, an alternative solution is needed where mixed and deciduous stands are prevalent. Measurement of ground plots over a wider range of species composition and forest structure is recommended for broader application to northern boreal forests and to further assess the potential role of the shadow fraction method in national-scale inventory programs.

Mountain maple and balsam fir early response to partial and clear-cut harvesting under aspen stands of northern Quebec

2004 ◽  
Vol 34 (10) ◽  
pp. 2049-2059 ◽  
Author(s):  
Laurence Bourgeois ◽  
Christian Messier ◽  
Suzanne Brais
Keyword(s):  
Boreal Forests ◽  
Block Design ◽  
Management Strategies ◽  
Abies Balsamea ◽  
Basal Area ◽  
Early Response ◽  
Balsam Fir ◽  
Clear Cut ◽  
Canopy Opening ◽  
Slight Growth

This study is a component of the Sylviculture et aménagement forestier écosystémique project, which examines ecosystem-based forest management strategies in mixedwood boreal forests. Four harvesting treatments, one no-harvest, one clearcut, and two partial cuts (33% and 61% of basal area removed), were applied to even-aged aspen stands according to a complete block design. Mountain maple (Acer spicatum Lamb.) and balsam fir (Abies balsamea (L.) Mill.) early response was examined to understand how they react to and interact with canopy opening. Only in clearcuts was maple's response (increase in growth and density) sustained and significant. Balsam fir suffered from a very slight "growth shock" 1 year after harvesting in both clear-cut and two-thirds partial-cut treatments, but growth and vigour increased with canopy opening during the next 2 years. The first year following harvesting, balsam fir growth was negatively affected by understorey aspen and mountain maple. Our results show that the two-thirds partial harvesting treatment could speed up the conversion of pure aspen stands toward mixedwood.

Contribution to the automation of the calculations involving the forest inventory with the aid of an office computer

1970 ◽  
Vol 20 ◽  
Author(s):  
R. Goossens
Keyword(s):  
Tree Species ◽  
Forest Inventory ◽  
Basal Area ◽  
Annual Increment ◽  
Mixed Stands ◽  
Mean Values ◽  
Standing Trees ◽  
General Program ◽  
Magnetic Card ◽  
The Right

Contribution to the automation of the calculations involving  the forest inventory with the aid of an office computer - In this contribution an attempt was made to perform the  calculations involving the forest inventory by means of an office computer  Olivetti P203.     The general program (flowchart 1), identical for all tree species except  for the values of the different parameters, occupies the tracks A and B of a  magnetic card used with this computer. For each tree species one magnetic  card is required, while some supplementary cards are used for the  subroutines. The first subroutine (flowchart 1) enables us to preserve  temporarily the subtotals between two tree species (mixed stands) and so  called special or stand cards (SC). After the last tree species the totals  per ha are calculated and printed on the former, the average trees occuring  on the line below. Appendix 1 gives an example of a similar form resulting  from calculations involving a sampling in a mixed stand consisting of Oak  (code 11), Red oak (code 12), Japanese larch (code 24) and Beech (code 13).  On this form we find from the left to the right: the diameter class (m), the  number of trees per ha, the basal area (m2/ha), the current annual increment  of the basal area (m2/year/ha), current annual volume increment (m3/year/ha),  the volume (m3/ha) and the money value of the standing trees (Bfr/ha). On the  line before the last, the totals of the quantities mentioned above and of all  the tree species together are to be found. The last line gives a survey of  the average values dg, g, ig, ig, v and w.     Besides this form each stand or plot has a so-called 'stand card SC' on  wich the totals cited above as well as the area of the stand or the plot and  its code are stored. Similar 'stand card' may replace in many cases  completely the classical index cards; moreover they have the advantage that  the data can be entered directly into the computer so that further  calculations, classifications or tabling can be carried out by means of an  appropriate program or subroutine. The subroutine 2 (flowchart 2) illustrates  the use of similar cards for a series of stands or eventually a complete  forest, the real values of the different quantities above are calculated and  tabled (taking into account the area). At the same time the general totals  and the general mean values per ha, as well as the average trees are  calculated and printed. Appendix 2 represents a form resulting from such  calculations by means of subroutine 2.

scholarly journals Fall incidents in nursing home residents: development of a predictive clinical rule (FINDER)

BMJ Open ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. e042941
Author(s):  
Vanja Milosevic ◽  
Aimee Linkens ◽  
Bjorn Winkens ◽  
Kim P G M Hurkens ◽  
Dennis Wong ◽  
...  
Keyword(s):  
Nursing Home ◽  
Fall Risk ◽  
Nursing Home Residents ◽  
High Sensitivity ◽  
Secondary Outcome ◽  
Operating Characteristics ◽  
Retrospective Case ◽  
Data Set ◽  
Fall Incident ◽  
Clinical Rule

ObjectivesTo develop (part I) and validate (part II) an electronic fall risk clinical rule (CR) to identify nursing home residents (NH-residents) at risk for a fall incident.DesignObservational, retrospective case–control study.SettingNursing homes.ParticipantsA total of 1668 (824 in part I, 844 in part II) NH-residents from the Netherlands were included. Data of participants from part I were excluded in part II.Primary and secondary outcome measuresDevelopment and validation of a fall risk CR in NH-residents. Logistic regression analysis was conducted to identify the fall risk-variables in part I. With these, three CRs were developed (ie, at the day of the fall incident and 3 days and 5 days prior to the fall incident). The overall prediction quality of the CRs were assessed using the area under the receiver operating characteristics (AUROC), and a cut-off value was determined for the predicted risk ensuring a sensitivity ≥0.85. Finally, one CR was chosen and validated in part II using a new retrospective data set.ResultsEleven fall risk-variables were identified in part I. The AUROCs of the three CRs form part I were similar: the AUROC for models I, II and III were 0.714 (95% CI: 0.679 to 0.748), 0.715 (95% CI: 0.680 to 0.750) and 0.709 (95% CI: 0.674 to 0.744), respectively. Model III (ie, 5 days prior to the fall incident) was chosen for validation in part II. The validated AUROC of the CR, obtained in part II, was 0.603 (95% CI: 0.565 to 0.641) with a sensitivity of 83.41% (95% CI: 79.44% to 86.76%) and a specificity of 27.25% (95% CI 23.11% to 31.81%).ConclusionMedication data and resident characteristics alone are not sufficient enough to develop a successful CR with a high sensitivity and specificity to predict fall risk in NH-residents.Trial registration numberNot available.

scholarly journals Evaluating Presence/Absence of Target Microbes in Microbiological Tests

2000 ◽  
Vol 83 (6) ◽  
pp. 1429-1434
Author(s):  
Robert J Blodgett ◽  
Anthony D Hitchins
Keyword(s):  
Performance Studies ◽  
Collaborative Study ◽  
False Negative ◽  
The Other ◽  
Test Results ◽  
Logistic Curve ◽  
Microbiological Method ◽  
Test Portion ◽  
Method Performance ◽  
Data Set

Abstract A typical qualitative microbiological method performance (collaborative) study gathers a data set of responses about a test for the presence or absence of a target microbe. We developed 2 models that estimate false-positive and false-negative rates. One model assumes a constant probability that the tests will indicate the target microbe is present for any positive concentration in the test portion. The other model assumes that this probability follows a logistic curve. Test results from several method performance studies illustrate these estimates.

scholarly journals Evaluating the Performance of a Forest Succession Model to Predict the Long-Term Dynamics of Tree Species in Mixed Boreal Forests Using Historical Data in Northern Ontario, Canada

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1181
Author(s):  
Guy R. Larocque ◽  
F. Wayne Bell
Keyword(s):  
Populus Tremuloides ◽  
Boreal Forests ◽  
Forest Ecosystems ◽  
Forest Succession ◽  
Regional Scale ◽  
Abies Balsamea ◽  
Forest Growth ◽  
Northern Ontario ◽  
Phase Dynamics

Environmental concerns and economic pressures on forest ecosystems have led to the development of sustainable forest management practices. As a consequence, forest managers must evaluate the long-term effects of their management decisions on potential forest successional pathways. As changes in forest ecosystems occur very slowly, simulation models are logical and efficient tools to predict the patterns of forest growth and succession. However, as models are an imperfect representation of reality, it is desirable to evaluate them with historical long-term forest data. Using remeasured tree and stand data from three data sets from two ecoregions in northern Ontario, the succession gap model ZELIG-CFS was evaluated for mixed boreal forests composed of black spruce (Picea mariana [Mill.] B.S.P.), balsam fir (Abies balsamea [L.] Mill.), jack pine (Pinus banksiana L.), white spruce (Picea glauca [Moench] Voss), trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.), northern white cedar (Thuja occidentalis L.), American larch (Larix laricina [Du Roi] K. Koch), and balsam poplar (Populus balsamefera L.). The comparison of observed and predicted basal areas and stand densities indicated that ZELIG-CFS predicted the dynamics of most species consistently for periods varying between 5 and 57 simulation years. The patterns of forest succession observed in this study support gap phase dynamics at the plot scale and shade-tolerance complementarity hypotheses at the regional scale.

scholarly journals Evaluation of the Simard et al. 2011 Global Canopy Height Map in Boreal Forests

2020 ◽  
Vol 12 (7) ◽  
pp. 1114
Author(s):  
Wei Yang ◽  
Akihiko Kondoh
Keyword(s):  
Boreal Forests ◽  
Forest Canopy ◽  
Spatial Separation ◽  
Canopy Height ◽  
Tree Cover ◽  
Data Sets ◽  
Data Set ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

Light detection and ranging (LiDAR) provides a state-of-the-art technique for measuring forest canopy height. Nevertheless, it may miss some forests due to its spatial separation of individual spots. A number of efforts have been made to overcome the limitation of global LiDAR datasets to generate wall-to-wall canopy height products, among which a global satellite product produced by Simard et al. (2011) (henceforth, the Simard-map) has been the most widely applied. However, the accuracy of the Simard-map is uncertain in boreal forests, which play important roles in the terrestrial carbon cycle and are encountering more extensive climate changes than the global average. In this letter, we evaluated the Simard-map in boreal forests through a literature review of field canopy height. Our comparison shows that the Simard-map yielded a significant correlation with the field canopy height (R2 = 0.68 and p < 0.001). However, remarkable biases were observed with the root mean square error (RMSE), regression slope, and intercept of 6.88 m, 0.448, and 10.429, respectively. Interestingly, we found that the evaluation results showed an identical trend with a validation of moderate-resolution imaging spectroradiometer (MODIS) tree-cover product (MOD44B) in boreal forests, which was used as a crucial input data set for generating the Simard-map. That is, both the Simard-map and MOD44B yielded an overestimation (underestimation) in the lower (upper) tails of the scatterplots between the field and satellite data sets. This indicates that the MOD44B product is the likely source of error for the estimation biases of the Simard-map. Finally, a field calibration was performed to improve the Simard-map in boreal forests by compensating for the estimation biases and discarding non-forest areas, which provided a more reliable canopy height product for future applications.

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