Site-related Characteristics Research Articles

Assessing the measuring time of forest plots

Forests provide a wide range of ecosystem services and information requirements on forests have grown considerably. Nevertheless, collecting information in the forest is expensive and for this reason assessment of forest resources strongly relies on statistical sampling. However, plot measurement remains essential even when remote-sensing data are used, and field assessments are still among the costliest components of forest inventories. Studies on the costs for plots survey are limited and usually based on expert evaluation rather than on data. This article analysed the relationship between the time needed for measuring forest plots and their site-related characteristics (slope, terrain roughness), stand features (number of trees, subsample trees, stumps, coarse woody debris, understorey vegetation) and protocol-related procedures, by means of univariate and multivariate analyses. Analyses showed that the time needed for measuring plots depends on the workload or the intensity of fieldwork. Especially, the number of variables surveyed matters, because the variables explained the measuring time variation by an additive effect, suggesting that within a complex field protocol the total number of measurements taken may not represent properly the overall intensity of work. Marking in an effective way permanent plots is recommendable because the retrieval success of the pins buried into the ground was the most important explanatory variable. Presence of understorey vegetation was more important than the number of individuals measured. The results obtained are consistent and logical, but the variance explained was limited, suggesting that predictability of the measuring time under complex field protocols might be intrinsically limited by the interactions among factors with opposite effects and especially by the adaptation of the surveyors to specific circumstances. For example, effects of physical tiredness were not detected in the days when two plots were measured; conversely, measuring a second plot reduced the measuring time of the first, an event most likely dependent on the surveyors’ behaviour. Under the conclusion that predictability is low by nature, the inference of studies based on simulation

Uncertainty in primary and secondary topographic attributes caused by digital elevation model spatial resolution

Digital elevation models (DEMs) are increasingly being used to explain different soil and site-related characteristics using a variety of modelled topographic properties and their frequencies. It is well known that the grid cell size of a raster DEM significantly affects derived primary and secondary topographic attirbutes, such as elevation, slope, topographic position index, and wind exposition index. This study investigates the impact of increasing DEM spatial resolution on spatial distortion (defined by mean absolute error (MAE)) in two contrasting sites and tests two different data-obtaining procedures (average plot vs. single point). Findings detected and quantified significant error(s) caused by coarsening DEM spatial resolution. In addition, the plot average measurement procedure was more representative for any bounded area than a value extracted from a single point measurement. These findings provide important guidance for creating and using topographic attributes across a range of applications. This study recommends using DEM resolution of <15 m to derive primary and secondary topographic attributes. However, the optimal resolution is scale dependent and related with landscape; henceforth, coarser resolution may be sufficient for representing large-scale topographic features.

Gingival Thickness and Outcome of Periodontal Plastic Surgery Procedures: A Meta-regression Analysis.

To evaluate the impact of soft tissue thickness (STT) on root coverage achieved with different periodontal plastic surgery procedures. Gingival recession has been managed successfully through various surgical approaches, with great variability in outcomes. Anatomic characteristics of the recipient site and selected technique account in part for this variability. Gingival flap thickness is one of the most critical site-related characteristics. An electronic search was conducted on the major databases (PubMed, Embase, Web of Science). Human prospective studies with at least 6 mo of follow-up and with a numeric baseline measurement for gingival thickness were eligible. Only studies including nonsmoking patients were considered. Variables included surgical approach, participant characteristics, local anatomic factors, and follow-up time. Primary outcome was mean percentage root coverage (%RC) achieved, and complete root coverage was a secondary outcome. A total of 42 studies were included (35 randomized controlled trials, 5 case series, 1 prospective cohort study, and 1 controlled clinical trial). Across studies, the pooled %RC was 81.9% (95% CI, 79.1% to 84.7%). The %RC was not significantly associated (P = 0.267) with baseline soft tissue thickness; however there was a significant (P = 0.031) inverse relationship between STT and %RC after 12-mo follow-up. Subgroup analysis showed that for no graft, there was a significant (P = 0.025) positive relationship between STT and %RC with the exclusion of the single outlier study based on STT. STT plays a limited role in predicting root coverage across all approaches; when flaps are performed with no graft, the effect of STT is most critical. The length of time following surgery appears to influence outcomes, with 12-mo follow-up offering greater insight. The results of this study can suggest to clinicians which periodontal plastic surgery technique to employ when treating challenging cases. In particular, it can be helpful when selecting the treatment approach to treat thin phenotype sites. This study could help clinicians provide a more appropriate treatment decision in such cases.

Effect of UV-B radiation on the content of UV-B absorbing compounds and photosynthetic parameters in Parmotrema austrosinense from two contrasting habitats.

We studied the resistance of Parmotrema austrosinense to UV-B stress. We focused on the effects of a high dose UV-B radiation on the content of chlorophylls, carotenoids and UV-B screening compounds. Photosynthetic parameters were measured by chlorophyll fluorescence (potential and effective quantum yields, photochemical and non-photochemical quenching) and evaluated in control and UV-B-treated lichens. Lichens from two different locations in Cordoba, Argentina, were selected: (i) high altitude and dry plots at (Los Gigantes) and (ii) lowland high salinity plots (Salinas Grandes). UV-B treatment led to a decrease in the content of photosynthetic pigments and UV-B screens (absorbance decrease in 220-350nm) in the samples from Salinas Grandes, while in Los Gigantes samples, an increase in UV-B screen content was observed. Chlorophyll fluorescence parameters showed a UV-B-induced decline in FV /FM , ΦPSII and qP indicating limitation of primary photosynthetic processes in photosystem II (PSII) of symbiotic alga, more pronounced in Salinas Grandes samples. Protective mechanism of PSII were activated by the UV-B treatment to a higher extent in samples from Salinas Grandes (NPQ 0.48) than in Los Gigantes samples (NPQ 0.26). We concluded that site-related characteristics, and in particular different UV-B radiation regimen, had a strong effect on resistance of the photosynthetic apparatus of P.austrosinense to UV-B radiation.

Abstract TP135: Control of Vascular Risk Factors at Baseline in CREST-2

Rationale: Asymptomatic carotid stenosis is commonly seen in medical practice. CREST-2 is a pair of concurrent two-arm multi-site randomized trials of intensive medical management versus intensive medical management in combination with revascularization by endarterectomy or stenting. It is not known how often patients entering the trials have opportunities for further risk factor reduction at study entry and whether these opportunities vary across trial centers. Methods: Baseline data on 683 patients from 109 clinical sites were used for these analyses. We determined the rates of control at baseline for systolic blood pressure (SBP), defined as &lt;140 mmHg (or ≥140 with &gt;15mmHg orthostatic drop), and low density lipoprotein (LDL), defined as &lt;70 mg/dl. We then tested differences in these baseline control rates by site-related characteristics, including site type, StrokeNet site vs. not, specialty of site Principal Investigator (PI), type of hospital, central vs local IRB, type of research team and whether site is enrolling in one or both trials. P-value &lt;0.05 was considered significant. Results: At baseline, the mean SBP was 140.4±20.5 mmHg, but only 62% of participants were in target. The mean LDL at baseline was 83.7±36.9, mg/dl, with 42% in target. None of the site characteristics were associated with a higher level of control for SBP at baseline. The only characteristic associated with having a higher level of LDL control was sites enrolling in only the CAS trial (57%) compared to those enrolling in the CEA only (24%) or in both trials (42%) (p=0.02). Conclusions: Opportunities to improve on risk factors are common among CREST-2 participants, but site characteristics did not predict the likelihood of being at goal for SBP while sites enrolling in only the CAS trial had a higher level of LDL control.

A test of the delayed oak dominance hypothesis at mid-rotation in developing upland stands

Abstract Red maple often dominates tree regeneration following the harvest of upland oak stands in eastern North America. An open question is whether the oak component of the new stands will eventually reassert dominance (delayed oak dominance hypothesis) or whether red maple will succeed as a major, new overstory component on these sites (red maple dominance hypothesis). We examined changes between the 3rd and 4th decades of growth (mean interval 13 years) in 46 stands on formerly oak-dominated sites in the Blue Ridge (BlRi), Ridge and Valley (RiVa), and Appalachian Plateau (ApPl) physiographic provinces of the central Appalachians. Almost without exception, the new stands in their 4th decade (mean age 38 yrs) had less oak and more red maple than did their predecessors. All ApPl stands had failed to develop a substantial component of oak early in stand development, and most were dominated by red maple in their 4th decade. Most BlRi stands had become dominated by oak by their 4th decade, and changes between the 3rd and 4th decades show that oak is progressively becoming more dominant by displacing the relatively minor component of red maple that remains. The success of oak was generally intermediate in the RiVa, where red maple retained an approximately co-equal position of dominance with oak between the 3rd and 4th decades and in some stands advanced in dominance against oak. We suggest a nuanced interpretation of delayed oak dominance as an emergent and contingent property of individual trees and their neighborhoods. Both this and red maple dominance accurately describe developmental trajectories that are co-occurring in most of our stands, with one predominating over the other depending upon physiographic region and site-related characteristics. In general, development favored oaks where growth rates were slower and where species composition was more xerophytic. Red maple was favored on better sites, where delayed oak dominance appears to be a longer and ultimately less successful process.

Reforestation with Abies cephalonica Loudon: a five-year study of seedling survival

Purpose – The purpose of this paper is to establish the effects on the survival of outplanted Abies cephalonica Loudon seedlings of seedling characteristics, site characteristics and management practices. Design/methodology/approach – The study was carried out by repeatedly monitoring survival of seedlings during a five-year period as well as establishing statistical relationships with a set of variables belonging to the aforementioned categories. It took place in plots reforested after a wildfire in the Parnitha Mt. National Park, near Athens, Greece. Findings – The odds of survival were found to be affected by bedrock type, dominant vegetation, initial seedling height and use of shading implements. Artificial shading was most important during the first year, site-related characteristics gained importance with increasing age and seedling height was of relatively constant importance. Shifts in temporal patterns of mortality and damage symptoms occurrence suggest that the mechanisms causing mortality changed with increasing age. Practical implications – The use of large seedlings in reforestation projects involving A. cephalonica should be preferred. Shading improves survival but due to the high costs this technique could be reserved for unfavorable plots, e.g. on limestone. Planting A. cephalonica in marginal sites should be avoided. Originality/value – The knowledge of the performance of A. cephalonica outplanted seedlings is very limited, while the need is increasing due to the spread of wildfires in this previously unaffected habitat.

Treatment Moderators and Predictors of Outcome in the Treatment of Early Age Mania (TEAM) Study

Both the diagnosis and treatment of bipolar disorder in youth remain the subject of debate. In the Treatment of Early Age Mania (TEAM) study, risperidone was more effective than lithium or divalproex in children diagnosed with bipolar mania and highly comorbid with attention-deficit/hyperactivity disorder (ADHD). We searched for treatment moderators and predictors of outcome. TEAM was a multi-site, 8-week, randomized clinical trial of risperidone, lithium, or divalproex in 279 medication-naïve patients, aged 6 through 15 years, with a DSM-IV diagnosis of bipolar disorder currently in manic or mixed phase. Outcome measures included binary end-of-treatment responder status and change in the Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS) Mania Rating Scale (KMRS). Baseline demographics and clinical characteristics were tested as modifiers of treatment effect and as overall predictors of outcome. Moderator effects were detected for site, ADHD, and obesity. Across sites, the response ratio (RR) for risperidone versus lithium ranged from 1.2 (95% confidence interval [CI] = 0.8-1.7) to 8.3 (95% CI = 1.1-60.8), and for risperidone versus divalproex from 1.3 (95% CI = 0.8-2.2) to 10.5 (95% CI = 1.4-77.7). The RR for risperidone versus lithium was 2.1 for patients with ADHD, but 1.0 for those without ADHD, and 2.3 (95% CI = 1.6-3.3) for nonobese patients, but 1.1 (95% CI = 0.6-2.0) for obese ones. Older age and less severe ADHD symptoms were associated with greater improvement on the KMRS. Risperidone was more effective than lithium or divalproex across the demographics and clinical characteristics of the sample, but the magnitude of its effect was influenced by site-related characteristics and presence of ADHD. Clinical trial registration information--Treatment of Early Age Mania; http://clinicaltrials.gov/; NCT00057681.

Endozoochorous seed dispersal by cattle and horse in a spatially heterogeneous landscape

Seed dispersal has become an important issue in plant ecology and restoration management. In this paper we examined dung germinating seed content and seed deposition patterns of horses (Shetland and Konik breeds) and Scottish Highland cattle grazing two coastal dune nature reserves. Two times 2.5 l of fresh dung from each type of herbivore were collected during seven sessions in the main fruiting season. Dung samples were placed under greenhouse conditions after drying and cooling. Animal defecation patterns were derived from a study of herbivore activities during 6 h observation sessions 8 times a month. One hundred and seventeen plant species i.e. 27% of all species occurring in the study area, were recorded as seedlings emerging from the dung samples. The most abundantly and frequently recorded plant species were Urtica dioica, Juncus spp. and different species of Poaceae and Caryophyllaceae. In general seedling density is high (1158 seedlings/dung sample). Seedling density and species richness were further analysed in order to detect temporal variability and possible animal and site related characteristics. Dung deposition patterns reflect a non-random use of habitats and hence a non-random seed deposition among habitats. Calculated seed deposition per square meter ranged from a few (<10 germinating seeds) to more than 100 in the most frequently selected habitats. From the herbivores’ selective habitat use and their estimated mean retention time we can further assume their ability for inter-habitat endozoochorous seed dispersal. This characteristic of large herbivores is further discussed in the light of nature management and restoration.

Mechanisms of dental plaque formation.

Much effort has been placed on elucidating the diverse mechanisms of microbial adhesion to tooth surfaces. Both specific and non-specific types of adhesion have been envisaged. Pioneer colonizers represent a selected part of the oral microflora, and it has been assumed that specific adhesin-receptor interactions between the microbial surface and the pellicle account for this specificity. Whereas microbial adhesion to tooth surfaces is a general prerequisite for initiation of plaque formation, microbial multiplication is probably the dominant feature in the build-up of dental plaque. Local environmental factors which influence the establishment and composition of the ultimate plaque community are therefore of greater importance than initial adhesion per se. The highly individual and site-related characteristics of the plaque flora illustrate the selective power of the environment. Environmental conditions are not uniform. Thus, each site represents its own conditions are not uniform. Thus, each site represents its own distinct ecosystem, and the microbial composition at the site depends on the outcome of a variety of host-microbial and microbial-microbial interactions. The relative in vivo significance of these interactions is difficult to assess.

Modelling psychosocial effects of exposure to solid waste facilities

A parallel case study design was used to investigate psychosocial effects in populations exposed to solid waste facilities. Psychosocial effects were defined as a complex of distress, dysfunction and disability, manifested in a range of psychosogical, social and behavioural outcomes, as a consequence of actual or perceived environmental contamination. This paper presents the results of logistic regression analyses designed to identify determinants of psychosocial effects of exposure. The data come from an epidemiologic survey of residents ( N = 696) living within a prescribed radius from each of three solid waste facilities in southern Ontario. The analytical model has three main components: external variables (e.g. individual and exposure-related variables); mediating variables (e.g. social network membership and involvement, general health status measures); and outcome variables (e.g. concern, effects and actions). Results for a series of site specific analyses show that outcome measures can be successfully explained by a combination of external and mediating factors. In general, variables from each of the three main components enter the concern-related models while the action models are clearly dominated by social network variables. Analyses using data from all three sites indicate the explanatory power of site-related characteristics. However, given the number and diversity of variables in the models, there is no support for a simple cause and effect relationship. The implication is that strategies aimed to address and alleviate psychosocial effects need to be specific to the characteristics of the populations in particular settings.

Microbial associations in periodontitis sites before and after treatment.

Duplicate samples from 110 periodontal sites of 6 mm or more pocket depth in 16 patients were analyzed for the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Capnocytophaga spp., Campylobacter rectus, Eikenella corrodens and Fusobacterium nucleatum. The sites were sampled before and after nonsurgical periodontal treatment. No statistically significant associations were found before treatment between any of the analyzed species. After treatment, statistically significant associations were found between E. corrodens and all the other species, F. nucleatum and P. intermedia; Capnocytophaga spp. and C. rectus; P. intermedia vs Capnocytophaga spp. and P. gingivalis; and C. rectus vs Capnocytophaga spp. and A. actinomycetemcomitans. Some of these associations could be explained either by patient-related factors or site-related characteristics such as the pocket depth. The proportion of P. gingivalis seemed to be unrelated to the proportion of P. intermedia in the samples. If one of the analyzed microbes was found in one of the sampled pockets in a patient, the probability of finding that microbe in all the sampled sites in the same patient before treatment was more than 50%. This probability was reduced after treatment for many species, especially P. gingivalis, which showed a probability of zero. The probability of detecting a bacterial species on at least one additional site if it was present on one in the same individual was nearly 100%, both before and after treatment, for all species studied. This study has shown several potential microbial associations in the subgingival plaque flora of deep periodontal pockets.(ABSTRACT TRUNCATED AT 250 WORDS)

The impact of site characteristics on housing cost estimates

Hedonic housing regressions using micro data for owners and renters from the 1972–1973 Consumer Expenditure Survey are presented. By including tract characteristics and public goods in these regressions, evidence is presented which indicates sensitivity of the physical housing variable coefficients to the choice of included site-related characteristics. Furthermore, omission of public good variables can result in misleading, and possibly perverse, coefficients on access. Intermetropolitan housing cost estimates, however, are shown to be relatively insensitive to the choice of site-related characteristics.

A comparative location analysis of a retail activity: The gasoline service station

This study focuses on the competitive processes and locational patterns of a convenience retail activity within two urban areas exhibiting distinct differences in operational characteristics. Impacts of various economic, demographic, and political environmental factors on the distribution of gasoline service stations in urbanized Hong Kong and metropolitan Denver are examined. Measurement of distributional patterns (utilizing nearest-neighbor and spatial association statistics) and socioeconomic/demographic influences (employing regression analysis) reveal remarkable similarities between the two areas. Investigation of several site-related characteristics (zoning and intersection orientation) suggests that they may be significant agglomerative influences accounting both for the consistent location patterns as well as the weak explanatory power of demand variables.