Crown Coverage Research Articles

La stima delle superfici forestali per l'Italia: le incertezze del Nuovo Inventario delle Foreste e del Carbonio

Abstract: Following the entry of the Kyoto Protocol (KP) into force, a new functionality has been added to the National Forestry Inventories (NFI), which are used to account for carbon stock changes in forest carbon pools. All Countries have to select a national forest definition in accordance with the KP rules. The KP requests that minimum thresholds for area, crown coverage and tree height are set. Thus the adopted forest definition drives the accounting of any forest-related land use and land-use change activities. The new NFIs should characterize the forest variables in accordance with the new forest definitions and thus they should adopt methodologies which are able to represent forest area as defined. The Italian NFI has applied a new methodology which is not in line with its own forest definition since this method considers new criteria of homogeneity in order to classify forest area. The homogeneity criteria requires a subjective analysis of the area around each sample point; thus the sample area assignment is not carried out objectively and univocally and consequently measurements are not reproducible either in time or space. The authors suggest an improved methodology that would allow the sampling of the national territory in line with the NFI forest definition. The main characteristic of the proposed methodology is to assign and to analyze a circular area around each sample point. The size of the circular area is taken equal to the NFI forest definition minimum threshold. The application of this methodology would result in objective and univocal measurements which are reproducible either in time or space.

La stima delle superfici forestali per l’Italia: le incertezze del Nuovo Inventario delle Foreste e del Carbonio

Following the entry of the Kyoto Protocol (KP) into force, a new functionality has been added to the National Forestry Inventories (NFI), which are used to account for carbon stock changes in forest carbon pools. All Countries have to select a national forest definition in accordance with the KP rules. The KP requests that minimum thresholds for area, crown coverage and tree height are set. Thus the adopted forest definition drives the accounting of any forest-related land use and land-use change activities. The new NFIs should characterize the forest variables in accordance with the new forest definitions and thus they should adopt methodologies which are able to represent forest area as defined. The Italian NFI has applied a new methodology which is not in line with its own forest definition since this method considers new criteria of homogeneity in order to classify forest area. The homogeneity criteria requires a subjective analysis of the area around each sample point; thus the sample area assignment is not carried out objectively and univocally and consequently measurements are not reproducible either in time or space. The authors suggest an improved methodology that would allow the sampling of the national territory in line with the NFI forest definition. The main characteristic of the proposed methodology is to assign and to analyze a circular area around each sample point. The size of the circular area is taken equal to the NFI forest definition minimum threshold. The application of this methodology would result in objective and univocal measurements which are reproducible either in time or space.

Behavior of four broad-leaved tree species used to revegetate eroded granite hill slopes

Information on primary growth behavior after planting is required for mixed-plantation revegetation using broad-leaved species. To estimate primary growth, especially from the perspective of crown coverage and changing growth rates, we examined the growth and survival of four broad-leaved species that are frequently used in erosion-control plantations in Japan. The species studied were Myrica rubra Sieb. et Zucc., Alnus pendula Matsum., Quercus glauca Thunb., and Q. serrata Thunb. The survival, height, and basal diameter of planted trees were measured over a 4-year period, and crown area was calculated over a 3-year period. We found a negative relationship between relative growth rate (RGR) and survival rate, suggesting that fast growth may be fatal when resources are severely limited. The relative height growth rate (RHGR) of A. pendula was especially high during the early period of the study (1997–1999) and then drastically declined, whereas the opposite tendency was observed in Q. glauca. The results of stem allometry analyses conformed to the specific relationships between height growth and diameter growth of the four species; increases in stem thickness based on height increments were smaller in the pioneer species A. pendula. Between-species differences in coverage per planted tree (mean crown area multiplied by survival rate) were small as a result of the negative relationship between coverage area and survival rate.

Long-term survival of endodontically treated molars without crown coverage: A retrospective cohort study

Teeth are weakened after endodontic treatment and should, ideally, be crowned, especially posterior teeth. However, this is not always possible. Information about the longevity of endodontically treated teeth without crown coverage may assist in selecting appropriate treatment modalities. The aims of this cohort study were to evaluate the survival rate for endodontically treated molars without crown coverage and to identify possible related factors. A total of 220 endodontically treated permanent molar teeth in 203 subjects on a waiting list for fixed prosthodontic treatment at the Faculty of Dentistry-Mahidol University, Thailand, were included. Follow-up data were derived from a clinical examination and review of the dental record and radiographs. Subjects were not included in the study if teeth had provisional crowns, definitive restorations with cuspal coverage, or with dowel and core and/or crown restorations. The outcome evaluated was defined as a failure if there were negative findings in the condition of a tooth that required a restoration, tooth repair, or extraction. Tooth loss due to endodontic and periodontal reasons was excluded. The independent variables assessed were patient age, gender, location (maxilla or mandible), the existence of an opposing dentition and adjacent teeth, remaining tooth structure, and types of restorative material. Kaplan-Meier analysis with a 95% confidence level was used to calculate the survival probability, and a log-rank test was used to determine whether significant differences existed. Overall survival rates of endodontically treated molars without crowns at 1, 2, and 5 years were 96%, 88%, and 36%, respectively. With greater amounts of coronal tooth structure remaining, the survival probability increased. Molar teeth with maximum tooth structure remaining after endodontic treatment had a survival rate of 78% at 5 years. Restorations with direct composite had a better survival rate than conventional amalgam and reinforced zinc oxide and eugenol with polymethacrylate restorations. Within the limitations of this study, the amount of remaining tooth structure and types of restorative material have significant association with the longevity of endodontically treated molars without crown coverage.

Retrieval of forest biophysical variables by inverting a 3-D radiative transfer model and using high and very high resolution imagery

Obtaining detailed observations of the amount and condition of vegetation is an important issue for describing, understanding and modelling the role of the biosphere in the global carbon cycle. Here, multispectral optical imagery was used for retrieving biophysical variables through the inversion of a 3-D radiative transfer model. Two inversion procedures are presented: a classical procedure for high resolution imagery and an innovative procedure specifically designed for very high resolution imagery (resolution around 1 m). They were tested with SPOT ('Satellite Pour l'Observation de la Terre') and Ikonos images, respectively. One of the objectives was to assess to which extent the inversion of high and very high resolution satellite imagery can help in assessing how Fontainebleau forest (France) was damaged by a very strong storm on December 1999. Retrieved biophysical variables are: Leaf Area Index (LAI), Crown Coverage (CC) and leaf chlorophyll concentration (C ab). Compared with ground measurements, SPOT-derived LAI has a root mean square error (RMSE) of around 1.4 at stand scale. This is not accurate enough to quantify the effects of the storm. However, LAI variation was assessed at a forest scale. On the other hand, the innovative procedure applied to Ikonos data led to more accurate results. For example, the relative error between estimated and ground measured LAI was improved, on average, from 23% (using 20 m resolution imagery) to 6% (using very high resolution imagery).

The effect of cigarette smoking on gingival bleeding.

The purpose of this study was to investigate the dose-dependent effect of cigarette smoking upon gingival bleeding on probing (BOP) in a large representative sample of the United States population (National Health and Nutrition Examination Survey III). Weighted multiple logistic regression was used to model bleeding on probing of 141,967 mesio-buccal sites in 12,385 individuals with complete case records on all covariates. Adjustments were made for age, gender, race/ethnicity, number of missing teeth, tooth type/jaw, root caries, full crown coverage, socioeconomic status (poverty/income ratio), and survey characteristics. The model stratified by presence of calculus (CALC) and increased probing depth (PD > or = 4 mm). Generalized estimating equations were used to account for dependence of sites within subjects. Smoking had a strong suppressive effect on gingival bleeding. The effect was strongest in heavier smokers (> 10 cigarettes/day) and smallest in former smokers. In healthy sites (no CALC, PD < or = 3 mm), the odds ratio (OR) of bleeding for sites in heavier smokers compared to never-smokers was 0.56 (95% CI: 0.45-0.70). Sites with CALC and/or PD > or = 4 mm were more likely to bleed in never-smokers (OR: 5.7; 95% CI: 4.3-7.6). This relationship was less evident among heavier smokers (OR: 1.3; 95% CI: 0.8-1.9). The effect of smoking did not differ between maxillary and mandibular molars, premolars, or incisors. Smoking exerts a strong, chronic, and dose-dependent suppressive effect on gingival bleeding on probing.

Kudzu (Pueraria montana) community responses to herbicides, burning, and high-density loblolly pine

Kudzu is an aggressive, nonnative vine that currently dominates an estimated 810,000 ha of mesic forest communities in the eastern United States. To test an integrated method of weed control, abundances of kudzu and other plant species were compared during 4 yr after six herbicide treatments (clopyralid, triclopyr, metsulfuron, picloram + 2,4-D, tebuthiuron, and a nonsprayed check), in which loblolly pines were planted at three densities (0, 1, and 4 seedlings m−2) to induce competition and potentially delay kudzu recovery. This split-plot design was replicated on each of the four kudzu-dominated sites near Aiken, SC. Relative light intensity (RLI) and soil water content (SWC) were measured periodically to identify mechanisms of interference among plant species. Two years after treatment (1999), crown coverage of kudzu averaged &lt; 2% in herbicide plots compared with 93% in the nonsprayed check, and these differences were maintained through 2001, except in clopyralid plots where kudzu cover increased to 15%. In 2001, pine interference was associated with 33, 56, and 67% reductions in biomass of kudzu, blackberry, and herbaceous vegetation, respectively. RLI in kudzu-dominated plots (4 to 15% of full sun) generally was less than half that of herbicide-treated plots. SWC was greatest in tebuthiuron plots, where total vegetation cover averaged 26% compared with 77 to 111% in other plots. None of the treatments eradicated kudzu, but combinations of herbicides and induced pine competition delayed its recovery.

Estimation of Tree Height and Stem Volume on Plots Using Airborne Laser Scanning

Abstract Airborne laser scanning has the ability to measure the vertical and horizontal structure of forest vegetation. The aim of this study is to investigate how measures derived from laser scanning data can be used in regression models for estimation of basal-area-weighted mean tree height and stem volume on 10 m radius field plots. Influence of laser scan angle on tree height estimation and on crown coverage area estimation is also investigated. The study area was located in southern Sweden (lat. 58°30′N, long. 13°40′E). The dominating tree species were Norway spruce (Picea abies L. Karst .), Scots pine (Pinus sylvestris L.) and birch (Betula spp.). Linear regression functions (R2=0.89–0.91) used to predict basal-area-weighted mean tree height had a Root Mean Square Error (RMSE) of 1.45–1.56 m, corresponding to 10–11% of average height. Scanning angle was not significant for estimation of basal-area-weighted mean tree height. Two regression models were used for prediction of stem volume. The first model (R2 = 0.90), with laser derived mean height together with laser derived crown coverage area as predicting variables, gave RMSE of 37 m3 ha-1, corresponding to 22% of average stem volume. The second model (R2=0.82), with laser derived tree height together with laser derived stem number as predicting variables, gave RMSE of 43 m3 ha-1, corresponding to 26% of average stem volume. The results implies that airborne laser scanning, if combined with a field sample, has potential of retrieving information with high spatial resolution (10 m radius plot) about tree height and stem volume for a forest area. FOR. SCI. 49(3):419–428.

植生自然度データを用いた都市の緑被地の把握手法の研究

This study aims to analyze the capacity of ‘urban green area of Japan’ within urban or suburban residential or open space area as a potential carbon sink for Kyoto Protocol. The study was carried out according to the follows steps: 1. Counting the number of ‘rban green areas in Japan’ from mesh data from “Japan’s national vegetation survey”. 2. Calculating a sample percentage canopy cover from the analysis of aerial photographs. 3. Calculating average canopy cover of ‘urban green areas’. Result for the average of tree crown coverage was 26.74%, and standard deviation was 16.07. From the results, it could be inferred that the total urban, suburban residential or open space area of Japan is about 1, 713km2. Moreover, according to comparisons of results between mesh data and administration data, there was no significant difference in the method of calculating the area by mesh data, and it was suggested that the total forest area can be used as a method for calculating the total.

Predicting tooth loss during a population-based study: role of attachment level in the presence of other dental conditions.

Our objectives were to quantify: 1) the association between incident tooth loss and prior periodontal attachment level; and 2) the contribution to tooth loss made by non-periodontal conditions in increasingly periodontally involved teeth. The Florida Dental Care Study was a prospective cohort study of persons who at baseline had at least 1 tooth and were 45 years or older. In-person interviews and clinical examinations were conducted at baseline, and at 24 and 48 months, with telephone interviews at 6-month intervals in between. A regression model was used to simultaneously quantify tooth-specific predictors of tooth loss, with person-level factors taken into account. Of the 687 persons who participated for a 48-month clinical examination, 36% lost 1 or more teeth during follow-up, and 5.0% of all teeth were lost. Attachment level up to 2 years before tooth loss was strongly predictive of incident tooth loss, with increases in risk for each millimeter in attachment loss. Certain other tooth-specific conditions (tooth mobility, bulk restoration fracture, decayed surfaces, filled surfaces, tooth type and arch location, root fragment) were strongly and independently associated with increased risk for tooth loss, while others were not (prosthetic crown coverage, cusp fracture, root surface defect). Propensity to choose extraction over other treatment alternatives, as reported by participants at baseline, was also strongly predictive of tooth loss. Increasingly severe attachment level was consistently associated with an increased risk for tooth loss in this sociodemographically diverse sample, with or without other tooth-specific conditions taken into account.

Cutover effects of the vegetation and soil in a natural forest

The disturbance produced on vegetation and soil after selective and total cutover of two sites were evaluated. The working area is located in Bovril, Entre Ríos, Argentina. It belongs to the Espinal Province, Ñandubay District, which has humid temperate climate and clay, compact and waterlogged soil. The woody structure was evaluated by the linear and fringe transecting methods. Each site was analyzed to study the floristic composition and the Sorensen similarity index (Is) was applied. Forage and weeds productivity was determined. The soil variables: total nitrogen, phosphorous, total organic carbon and others were estimated. The DCA design was continued. Dates was compared through ANOVA and Tukey test with SAS statistic siystem. The mean crown coverage for trees was 56,65 % and 38 % in the monte and the renoval. The tree density was 1,814 individuals ha–1 and 1,120 individuals ha–1 for both areas. The mean tree height was 4,10 and 2,9 m in each case. The shrub stratum presented few species and the herbaceous carpet was composed of Poaceae, Ciperaceae and Compositeae and a great diversity of others families of less importance. The annual forage volume was 3,505 and 3,271 kg M.S. ha–1 in both sites. The M.O., total nitrogen, assimilated phosphorous and nitrate reached higher values in forest vegetation soil than in soil lacking forest vegetation. The total removal of natural vegetation in the second gorwth forest produced a substantial alteration in its herbaceous, shrub-like and tree structure and the soil nutritive level.

Restorative procedures after root canal therapy

One of the most common indications for veterinary dental restoration involves replacing tooth structure after a root canal procedure. Special considerations are necessary due to the interaction of the restorative material with materials used to obturate the root canal. The restoration must provide a hermetic seal of the pulp chamber, as well as restore function. Combining several different restorative materials provides the best overall performance. In certain instances, full crown coverage is required to restore functional length or cervical anatomy.

Analyses of stand structure as a tool for silvicultural decisions — a case study in a Quercus petraea — Sorbus torminalis stand

The study applies structural indices using the example of an oak (Quercus petraea (Matt.) Liebl.) — chequer tree (Sorbus torminalis (L.) Crantz) stand in order to derive recommendations for the silvicultural treatment of Chequer trees. The investigated stand, located in the northern part of Bavaria, comprises eight tree species and four shrub species. Various indices were used to analyse the stand structure and the crown coverage frequency. It was shown that chequer trees, which are presently of high economic interest, are strongly oppressed in the upper layer and almost completely missing in the lower layers of the stand. The possible reasons for this finding and alternatives for the further management of the stand are discussed. Persistent and repeated thinnings in order to ensure sufficient crown development of the chequer trees seem to be essential for their survival.

Determination of the spatial distribution of trees from digital aerial photographs

This study examined the possibilities of using computerized digital aerial photograph interpretation in determining the spatial distribution of trees. The material of the study included eight mapped stands in the municipality of Hyytiälä (61°50′N and 24°18′E), in southern Finland. The aerial photographs used were taken in June 1995 at a scale of 1:5000. Two approaches for determining the spatial pattern of trees were used. Firstly, in the point-process based approach used in this study, the individual trees in the digital aerial photograph were segmented by a robust segmentation method, based on recognition of the pattern of tree crowns with sub-pixel accuracy. Secondly, the crown coverage was determined by region growing segmentation combined with active surface representation. The significance of the differences in the means of image coverage pattern indices between the various spatial distribution categories was tested with one-way variance analysis. Because the process misclassified clustered spatial patterns as regular patterns, and regular patterns as random patterns, the usability of digital aerial photographs seems to be limited for the point-process based determination of the spatial pattern of trees if the scale is 1:5000 or less. When image coverage pattern indices were applied, the differences in the means of the spatial distribution categories proved not to be clearly statistically significant due to the great variation within classes. However, interpretation of crown coverage could have applications in practical forestry due to the low resolution requirements for the images used.

Crown efficiency in a loblolly pine (Pinus taeda) spacing experiment

Crown efficiency was first defined by Assmann (1961. Waldertragskunde. BLV, München) as individual tree volume increment per unit of crown projection area. He hypothesized that within a given crown class, smaller crowns are more efficient because their ratio between crown surface and horizontal crown projection is higher. Data from a loblolly pine (Pinus taeda L.) spacing experiment were used to test if this hypothesis also holds in young loblolly pine stands and, if so, to determine if it explains the increment differences between spacings in the spacing experiment. Using individual tree height relative to plot dominant height to describe crown class, within-plot regression showed that crown efficiency decreased with crown size for trees below dominant height. This relationship was much less pronounced than indicated from Assmann's examples, although the crown surface to crown projection ratio behaved in the same way as Assmann had hypothesized. Crown efficiency as well as the crown surface to crown projection area ratio decreased with increasing density. Basal area increment per hectare increased until total crown closure approached 130% and then stayed constant. This major impact of total crown coverage brings into question the usefullness of crown efficiency as an indicator for unit area growth.

Crown efficiency in a loblolly pine (&lt;I&gt;Pinus taeda&lt;/I&gt;) spacing experiment

Crown efficiency was first defined by Assmann (1961. Waldertragskunde. BLV, München) as individual tree volume increment per unit of crown projection area. He hypothesized that within a given crown class, smaller crowns are more efficient because their ratio between crown surface and horizontal crown projection is higher. Data from a loblolly pine (Pinus taeda L.) spacing experiment were used to test if this hypothesis also holds in young loblolly pine stands and, if so, to determine if it explains the increment differences between spacings in the spacing experiment. Using individual tree height relative to plot dominant height to describe crown class, within-plot regression showed that crown efficiency decreased with crown size for trees below dominant height. This relationship was much less pronounced than indicated from Assmann's examples, although the crown surface to crown projection ratio behaved in the same way as Assmann had hypothesized. Crown efficiency as well as the crown surface to crown projection area ratio decreased with increasing density. Basal area increment per hectare increased until total crown closure approached 130% and then stayed constant. This major impact of total crown coverage brings into question the usefullness of crown efficiency as an indicator for unit area growth.

A Carbon Balance Model of Growth and Self-Pruning in Trees Based on Structural Relationships

Abstract A tree growth model is formulated based on structural relationships in a carbon balance framework. Three relationships are applied: (1) an allometric relationship between crown surface area and foliage area, (2) the principle of functional balance, and (3) the pipe-model theory. These assumptions lead to a model where the sizes of the functional parts of the tree are derivable from foliage weight, except for the pruning height of the crown. This is determined by defining a "self-pruning coefficient," which controls the allocation of growth between height growth and foliage growth. The tree model is applied to an average-tree based stand growth model where both the self-pruning coefficient and tree mortality are made functions of crown coverage. The model is quantified for Scots pine growing in southern Fenno-Scandia. The overall behavior of the model is realistic. The model responds to stocking density through the rate of self-pruning, lower stocking densities leading to larger crown ratios. It also responds to changes in parameters describing site quality in a realistic way, although the differences in stand density are not as large as expected. The predicted development of the biomass compartments in individual trees agrees well with data on dominant Scots pine trees in Finland. For. Sci. 43(1):7-24.

Incidence of pulp necrosis subsequent to pulp canal obliteration from trauma of permanent incisors

Little long-term data are available on the frequency by which pulp canal obliteration (PCO) subsequent to trauma leads to pulp necrosis (PN). In this study, 82 concussed, subluxated, extruded, laterally luxated, and intruded permanent incisors presenting with PCO were followed for a period of 7 to 22 yr (mean 16 yr). At final clinical examination, 51% of the observed teeth responded normally to electric pulp testing (EPT). An additional 40% of the teeth although not responding to EPT were clinically and radiographically within normal limits. Yellow discoloration was a frequent finding. During the observation period, periapical bone lesions suggesting PN developed in seven teeth (8.5%). Twenty-yr pulp survival rate was 84%, as determined from life-table calculations. There was no higher frequency of PN in obliterated teeth subjected to caries, new trauma, orthodontic treatment, or complete crown coverage than intact teeth. Although the incidence of PN in teeth displaying PCO seems to increase over the course of time, prophylactic endodontic intervention on a routine basis does not seem justified.

An analysis of the relationship between foliage biomass and crown surface area inPinus sylvestrisin Sweden

An allometric relationship between foliage biomass and crown surface area is investigated in a data set consisting of 54 fertilized and 99 unfertilized Scots pine (Pinus sylvestris L.) trees from 16 stands in Central Sweden. The allometric ratios for the unfertilized trees are shown to be weakly correlated with competition defined as tree height relative to dominant height (r = 0.475), and with crown coverage (r = ‐0.563). A slight level difference in the ratios can be detected between stands of different site moisture index. The overall relationship is nonlinear but becomes linear if the coefficient of proportionality is made dependent on stand average crown coverage. This also improves the percentage of explanation, which suggests that the allometry of the crown is related to the light conditions of the tree. Under fertilization, the relationship between foliage biomass and crown surface area seems less stable, at least if measured shortly after fertilization.

Vertical root fractures

In this study, I review, clinically and radiographically, 303 patients with 460 single or multirooted endodontically treated teeth. In all teeth, the therapy was performed by me with the use of final restoration of the crown with or without post and full cast crown coverage after treatment. The teeth were functioning for at least 3 years, without having received any other type of dental work since then. I evaluated the existence of vertical root fracture, the function of the teeth, the type of root canal therapy, the type and length of the post, and the type of retention of the post used in all 460 teeth. After statistical evaluation of the results, I found that 3.69% of the teeth had had vertical root fracture. Computer analysis, simple correlation hypothesis, and distribution method with 1 degree of freedom revealed significant correlation between vertical root fracture and the technique of instrumentation and obturation of the canal ( p = 0.025), the length of the post ( p = 0.05), and the existence of the post ( p = 0.05). On the contrary, I found no correlation between root fracture and type of retention of the prefabricated post used with respect to the method of obturation.