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Letteratura scientifica selezionata sul tema "Defoliation Measurement"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 11 febbraio 2022

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Articoli di riviste sul tema "Defoliation Measurement"

Hunt, Thomas E., Fikru J. Haile, W. Wyatt Hoback e Leon G. Higley. "Indirect Measurement of Insect Defoliation". Environmental Entomology 28, n. 6 (1 dicembre 1999): 1136–39. http://dx.doi.org/10.1093/ee/28.6.1136.

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Taylor, Sarah L., e David A. MacLean. "Validation of Spruce Budworm Outbreak History Developed from Aerial Sketch Mapping of Defoliation in New Brunswick". Northern Journal of Applied Forestry 25, n. 3 (1 settembre 2008): 139–45. http://dx.doi.org/10.1093/njaf/25.3.139.

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Abstract Aerial sketch mapping (ASM) of annual defoliation provides a means to quantify spruce budworm (Choristoneura fumiferana Clem.) outbreak histories, but accuracy is affected by factors such as navigation and weather conditions. We used ground-based defoliation estimates from 123 permanent sample plots (PSP) in New Brunswick and increment core growth data from a subset of PSPs, to validate ASM estimates of defoliation. From 1985 to 1993, 85% of 332 cases were correctly classified by aerial estimates as nil–light (0–30%) or moderate–severe (31–100%), with the proportion correct varying by measurement year, defoliation severity, and host species. Growth indices generated from 81 visually cross-dated and verified balsam fir (Abies balsamea [L.] Mill.) tree-ring series in 23 PSPs were significantly negatively correlated with aerial-derived cumulative defoliation for 87% of the PSPs, and correlation increased when aerial estimates were combined with ground survey data. We conclude that aerial surveys provide a reasonable estimate of defoliation history to estimate growth reduction.

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Zeide, Boris, e Lynne C. Thompson. "Impact of Spring Sawfly Defoliation on Growth of Loblolly Pine Stands". Southern Journal of Applied Forestry 29, n. 1 (1 febbraio 2005): 33–39. http://dx.doi.org/10.1093/sjaf/29.1.33.

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Abstract To estimate the impact of a single spring defoliation by loblolly pine sawfly (Neodiprion taedae linearis Ross), diameters of 3,006 loblolly pines from five locations in southeastern Arkansas were measured immediately after defoliation and two more times at 1-year intervals.The proportion of defoliation was assessed at each measurement. An insecticide was used in an attempt to prevent defoliation in subsequent years. Because tree growth depends on many factors, a multivariate multiple regression model was used to separate these effects. The model predicts thata single defoliation reduces annual diameter and volume increment by 17.4, 8.4, and 2.8% for the first, second, and third years after defoliation, respectively (the actual loss was 18.9 and 8.9% for the first 2 years). It was found that trees defoliated 20–40% actuallygrew faster than undefoliated trees. This response, called overcompensation, is a common reaction of plants to moderate stress. Potential losses from defoliation are greatest in sawtimber-sized stands between the ages of 25 and 35 years. The decision to control sawflies should take into accountstand age and time to final harvest. South. J. Appl. For. 29(1):33–39.

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Rast, Everette D., e Robert L. Brisbin. "Six-Year Effects of Two Late Spring Frosts on Appalachian Hardwoods". Northern Journal of Applied Forestry 4, n. 1 (1 marzo 1987): 26–28. http://dx.doi.org/10.1093/njaf/4.1.26.

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Abstract Severe late spring frosts can kill new shoots and leaves on commercial tree species at higher elevations. A previous short-term study has shown that the resulting defoliation and dieback does not seriously affect the radial growth or mortality of most species except American beech. In this study we found that defoliation, dieback, and radial growth increment were related to species and crown class. The radial growth increment of American beech was reduced to 70% of the previous 6-yr growth during the first year after the frost. The annual growth then increased consistently over the measurement period. Black cherry and sugar maple radial increment was only reduced to 88% of the previous 6-yr growth, but subsequent increments were much more variable. Epicormic branching on the lower bole of black cherry and beech increased significantly after defoliation occurred. At elevations above 3,200 ft, managers should discourage beech regeneration if timber production is the primary management objective. The potential for higher value products may be reduced because of increased variability in growth rate. North. J. Appl. For. 4:26-28, March 1987.

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Nowakowska, Justyna Anna, Marcin Stocki, Natalia Stocka, Sławomir Ślusarski, Miłosz Tkaczyk, João Maria Caetano, Mirela Tulik, Tom Hsiang e Tomasz Oszako. "Interactions between Phytophthora cactorum, Armillaria gallica and Betula pendula Roth. Seedlings Subjected to Defoliation". Forests 11, n. 10 (19 ottobre 2020): 1107. http://dx.doi.org/10.3390/f11101107.

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The purpose of this study was to better understand the interactive impact of two soil-borne pathogens, Phytophthora cactorum and Armillaria gallica, on seedlings of silver birch (Betula pendula Roth.) subjected to stress caused by mechanical defoliation, simulating primary insect feeding. This is the first experimental confirmation of silver birch seedling root damage (and in consequence shoot mortality) caused by the additive effect of defoliation stress and P. cactorum inoculation via soil. However, the most severe damage to roots occurred after A. gallica inoculation. One year after treatments, chlorophyll fluorescence measurement, and gas chromatography coupled with mass spectrometry (GC-MS) were used to analyze the photosynthetic activity in leaves, the volatile organic compounds (VOCs) emitted by the birch leaves, and chemical compounds from the roots. The cumulative effect of the two pathogens and partial defoliation reduced photosynthetic activity, suggesting dysfunction of photosystem PSII due to the applied stresses. In summary, it seems that the main differences in photosynthetic performance could be attributed to Armillaria infection. The birch leaves in seedlings exposed to 50% defoliation, and inoculation with P.cactorum and A. gallica, emitted more aromatic carbonyls and alcohols, as well as half as much aliphatic esters, compared to controls. In infected birch roots, the production of phenols, triterpenes, and fatty alcohols increased, but fatty acids decreased. Higher levels of aromatic carbonyls and alcohols in leaves, as well as phenolic compounds in the roots of stressed birches (compared to control) suggest an activation of plant systemic acquired resistance (SAR).

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Buonaccorsi, John P. "Prediction in the Presence of Measurement Error: General Discussion and an Example Predicting Defoliation". Biometrics 51, n. 4 (dicembre 1995): 1562. http://dx.doi.org/10.2307/2533288.

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MacKinnon, Wayne E., e David A. MacLean. "Effects of surrounding forest and site conditions on growth reduction of balsam fir and spruce caused by spruce budworm defoliation". Canadian Journal of Forest Research 34, n. 11 (1 novembre 2004): 2351–62. http://dx.doi.org/10.1139/x04-115.

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The species composition of surrounding forest and site characteristics have been postulated to influence growth loss caused by eastern spruce budworm (Choristoneura fumiferana Clem.) defoliation. Forty spruce (Picea spp.) and balsam fir (Abies balsamea (L.) Mill.) stands located in north-central New Brunswick, Canada, were measured for defoliation and tree growth and used to determine the effects of surrounding forest (softwood, mixedwood), site (wet soil nutrient poor; moist soil nutrient rich), and species group (balsam fir, spruce) on growth reduction caused by spruce budworm. Stem analysis of six trees per stand (total 240 trees) determined mean specific volume increment (SVI) per year in 19731993. There was relatively little defoliation during the 19891993 measurement period, and regression analyses showed that SVI was significantly (p = 0.0299) related to mean defoliation for only one of eight treatment classes: balsam fir on moistrich sites in mixedwood forests. However, two periods of earlier growth reduction were evident, and analysis of variance showed that balsam fir on wetpoor sites sustained 12% greater (p = 0.0071) reduction in SVI from 1987 to 1990 than balsam fir on moistrich sites. White spruce (Picea glauca (Moench) Voss) sustained 13% greater (p = 0.0198) reduction in SVI from 1973 to 1978 than red spruce (Picea rubens Sarg.) black spruce (Picea mariana (Mill.) BSP). Surrounding forest type did not significantly affect SVI reduction from 1973 to 1978 or from 1987 to 1990, but from 1973 to 1978 stands in softwood forest sustained 5%8% more growth reduction than those in mixedwood forest.

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Johnson, Lee F., e Lars L. Pierce. "Indirect Measurement of Leaf Area Index in California North Coast Vineyards". HortScience 39, n. 2 (aprile 2004): 236–38. http://dx.doi.org/10.21273/hortsci.39.2.236.

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The performance of the LI-COR LAI-2000 Plant Canopy Analyzer (PCA) for indirect measurement of leaf area index (LAI) was evaluated in vineyards of California's North Coast region. Twelve plots were established, representing vineyards of differing trellis, cultivar, and planting density. Mean LAI ranged from 0.5- to 2.25-m2 leaf area per m2 ground area by direct measurement (defoliation). Indirect LAI derived by a standard two-azimuth, diagonal-transect measurement protocol was significantly related to direct LAI (r2 = 0.78, P ≤ 0.001). However, the PCA underestimated direct LAI by about a factor of two. Narrowing the instrument's conical field of view from 148° to 56° increased indirect LAI by 13% to 60% in vertically trained plots, but still resulted in substantial underestimation of direct values. Use of this PCA protocol in vineyards should therefore be accompanied by direct measurement for calibration purposes.

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Pethybridge, Sarah J., Frank Hay, Paul Esker, Calum Wilson e Forrest W. Nutter. "Use of a Multispectral Radiometer for Noninvasive Assessments of Foliar Disease Caused by Ray Blight in Pyrethrum". Plant Disease 91, n. 11 (novembre 2007): 1397–406. http://dx.doi.org/10.1094/pdis-91-11-1397.

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Foliar disease due to ray blight (Phoma ligulicola) in pyrethrum was quantified at three locations over 2 years in Tasmania, Australia. To obtain a range of ray blight disease intensities, replicated plots were treated with fungicides that varied in efficacy to control ray blight. Visual disease assessments and measurement of canopy reflectance were made at least once during spring (September through December). Visual assessments involved removal of flowering stems at ground level from which measurements of defoliation severity and the incidence of stems with ray blight were obtained. Reflectance of sunlight from pyrethrum canopies was measured at 485, 560, 660, 830, and 1,650 nm using a handheld multispectral radiometer. Measurements from these wavelengths also were used to calculate all possible reflectance ratios, as well as four vegetative indices. Relationships between wavelength bands, reflectance ratios, vegetative indices, and disease intensity measures were described by linear regression analyses. Several wavelength bands, ratios, and vegetative indices were significantly related in a linear fashion to visual measures of disease intensity. The most consistent relationships, with high R2 and low coefficients of variation values, varied with crop growth stage over time. The ratio 830/560 was identified as the best predictor of stem height, defoliation severity, and number of flowers produced on each stem in October. However, reflectance within the near-infrared range (830 nm) and the difference vegetative index was superior in November. The use of radiometric assessment of disease was noninvasive and provided savings in disease assessment time, which is critical where visual assessment is difficult and requires destructive sampling, as with pyrethrum.

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Varago, André Luiz, Idemir Citadin, Marcos Robson Sachet, Gener Augusto Penso e Maria do Carmo Bassols Raseira. "Heritability of peach tree resistance to bacterial leaf spot". Pesquisa Agropecuária Brasileira 52, n. 5 (maggio 2017): 366–69. http://dx.doi.org/10.1590/s0100-204x2017000500010.

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Abstract: The objective of this work was to evaluate the broad-sense heritability reaction to bacterial leaf spot (Xanthomonas arboricola pv. pruni), in peach tree populations obtained from directed crosses. Disease severity and defoliation of the genotypes were evaluated in field conditions, with posterior measurement of the healthy leaf area duration (HAD). The observed average heritability (0.51) indicates that the use of the evaluated genitors can be effective for the development of cultivars with higher resistance to the disease.

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Più fonti

Tesi sul tema "Defoliation Measurement"

Perkowski, Matthew Paul. "An analysis of the gypsy moth event monitor modified forest vegetation simulator and the stand damage model using empirical long-term measurement plot data from the Appalachian hardwood and the Atlantic Coastal Plain mixed pine-hardwood regions". Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5856.

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Thesis (M.S.)--West Virginia University, 2008.
Title from document title page. Document formatted into pages; contains ix, 103 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 77-79).

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Capitoli di libri sul tema "Defoliation Measurement"

Ghosh, Swagata, Krishna Vidhata N., Sunil Kumar e Kousik Midya. "Seasonal Contrast of Land Surface Temperature in Faridabad". In Methods and Applications of Geospatial Technology in Sustainable Urbanism, 217–50. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-2249-3.ch008.

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The chapter has highlighted the adverse impact of conversion of natural land cover into urban concrete over inter-seasonal variation of land surface temperature (LST) in Faridabad district which is a major threat for sustainable urbanism. Apart from high LST in the dense urban area built-up in Faridabad city, inter-seasonal variation of LST has been observed in dry deciduous forested areas due to defoliation, fallow land, and over-grazed land in rural surrounding areas. Compared to NDVI, NDBI has significant positive and stable correlation with LST in all seasons (Pearson index: 0.35 to 0.60). Weaker correlation (Pearson index: 0.02 to 0.48) between NDVI and LST accounts for the seasonal impact over NDVI due to defoliation and agricultural practices over the study area. Overall, it can be remarked that image-based spectral indices and thermal band can be used for the evaluating thermal environmental contrast across seasons. Use of in situ measurement with good network of meteorological stations can validate satellite-derived LST better and increase the accuracy of the study.

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Atti di convegni sul tema "Defoliation Measurement"

Šerevičienė, Vaida, Vaida Vasiliauskienė, Dainius Paliulis e Jurgita Aleknaitė. "Integrated Evaluation of Road Transport Pollution Impact on the Urban Air". In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.048.

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With the number of vehicles increasing, the analysis of urban air pollution becomes expedient. This article deals with the integrated evaluation of road transport realised pollutant impact on the urban air. During research, it was carried out complex measurements of the air quality involving passive diffusive sampling for nitrogen dioxide, active measurement for particle matters, lichen sampling for heavy metals and visual assessment of trees defoliation. Obtained results showed the statistically reliable (p < 0.05) strong correlation (r = 0.83) between the number of passing vehicles and the concentration of particulate matter and there is even stronger correlation (r = 0.94; p < 0.05) between the concentration of nitrogen dioxide and the number of passing vehicles. It was observed during the analysis, that in measuring sites in which was determined 30% more intense defoliation process, also determined a higher NO2 (>10μg/m3) and lead (~10 mg/kg) concentrations. It can be argued that the source of mentioned pollutants is the same – motor transport, and their presence in the environment influences defoliation phenomenon.

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STRAUPE, Inga, e Līga LIEPA. "AN ASSESSMENT OF RETENTION TREES IN HYLOCOMIOSA FOREST TYPE IN SOUTHERN LATVIA". In RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.111.

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In Latvia the forest legislation requires that at least five living trees must be retained per hectare after clear-cutting. It is known that retention trees significantly increase the biodiversity in production forest landscape. After clear-cutting retention trees function as habitats for various lichens, mosses, insects, fungi and birds. Over time retention trees are incorporated into the young forests stand and provide presence of old trees, which is necessary for many endangered and rare species. After the death, these trees turn into coarse woody debris which is an essential habitat and feeding source for many taxa. However, the conservation and mortality of the retention trees has not been studied extensively because this approach has been established recently. The aim of this study was to evaluate development of the retention trees in Hylocomiosa type of forests in Southern Latvia. In total 12 young forest stands were surveyed in 2009 and 2015. The total area – 13.7 ha, on average forest stand size varies from 0.5 to 3.0 ha. All the studied sites were harvested in 2002, 2004, 2006 and 2008. All measurements of tree species, height, and diameter and defoliation class assessed and the status of tree (growing tree, coarse woody debris – snags, stems and downed logs) was indicated. Results show that after the studied period of seven years 24 retention trees died. Average level of the tree mortality is 15 %. The mortality level of Scots pine retention trees is 5.8 %, for aspen – 50 % and that for birch – 92.3 %. An average it is 8.5 green retention trees per 1 ha of young stand (22.9 m3 ha-1). On average 2.3 pieces coarse woody debris are per 1 ha of young stand (3.52 m3 ha-1), mostly - aspen wood (2.4 m3 ha-1). Woody debris of the young stands is divided to the first 4 decay levels according to classification (Stokland et al., 2001). 50 % of the listed woody debris is related to the 3rd decay level which means that woody debris is moderately decomposed.

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