Percent Green Cover Research Articles

Digital Image Analysis and Spectral Reflectance to Determine Turfgrass Quality

The limitations of the conventional visual rating system used to assess turfgrass quality include its subjective nature and the need for properly trained observers who can discern differences among treatments or turfgrass varieties. The objective of our study was to investigate if digital image analysis (DIA) and spectral reflectance [normalized difference vegetative index (NDVI)] can be used to evaluate turfgrass varieties. Trials were established at New Mexico State University and visual quality ratings, digital images, and NDVI were collected monthly on three warm‐season and three cool‐season variety trials and on one cool‐season and one warm‐season mixed species trial. Correlations among quality, NDVI, dark green color index (DGCI) and percent green cover (PCov) were computed. Multiple regression was used to determine if combining NDVI and DIA improved the association between visual turfgrass quality and other variables. Quality was most strongly associated with NDVI (R2 ranging from 0.37 to 0.65) for most datasets. Additionally, multiple linear regressions identified NDVI as the variable affecting a higher change in R2 when entered to the model than either DGCI or PCov. Visual quality had a weaker association with sampling date than did NDVI or DGCI, which indicates that NDVI may track quality changes more reliably over time. However, a stronger association between variety and visual quality than between variety and NDVI or DGCI indicates that a visual assessment detects varietal differences better. Therefore, it is questionable whether visual assessments can be replaced by NDVI or DIA to characterize the aesthetic appeal of turfgrasses accurately.

The effect of precipitation on vegetation cover over three landscape units in a protected semi-arid grassland: Temporal dynamics and suitable climatic index

The principal drivers that effectively determine the vitality of semi-arid grassland ecosystems are the amount and timing of precipitation. In contrast to well-established relationships between precipitation and some vegetation biophysical properties such as vegetation productivity and biomass, the effect of precipitation on percent vegetation cover in semi-arid grasslands are poorly understood. The percent green vegetation cover is an important indicator of ecosystem health, especially in a protected semi-arid grassland where dead material dominates vegetation canopy. Consequently, this study used field data, high spatial resolution SPOT satellite images, and low spatial but high temporal resolution AVHRR images to (1) analyze temporal variations in maximum percent green vegetation cover over three landscape units in a protected grassland from 1988 to 2007, and (2) investigate the performance of three commonly used climatic moisture indexes (accumulated precipitation – P; climate moisture index – CMI; and the modified Palmer drought severity index – MPDSI) in estimating percent vegetation cover. The results revealed moderate to strong links between percent vegetation cover and climate conditions in three landscape units. The selected indices were able to explain a relatively high proportion of variation in percent vegetation cover in the upland/sloped grassland (R2=0.41 for P, 0.45 for CMI, and 0.53 for MPDSI), low variation in the riparian shrub (R2=0.25 for P, 0.28 for CMI, and 0.32 for MPDSI), and even lower variation in the valley grassland (R2=0.09 for P, 0.14 for CMI, and 0.21 for MPDI). In comparison with accumulated precipitation, the CMI and MPDSI which considered water availability, were able to explain a much higher variation in percent vegetation cover over the three grassland landscape units. The results from this work provide new insight into the effects of precipitation/climatic factors upon different landscape units and further aid to establish a more complete picture in this field.

Establishment and Rooting Response of Bermudagrass Propagated with Saline Water and Subsurface Irrigation

ABSTRACTIrrigating with non‐potable, saline water using a subsurface drip system has been suggested as a strategy to conserve water used for turfgrass. However, it is unknown if turfgrasses can be established from sod when saline water is applied from the subsurface. A two‐year study was conducted at New Mexico State University to investigate the establishment of ‘Princess 77’ bermudagrass [Cynodon dactylon (L.) Pers.] from sod, irrigated from either a sprinkler or a subsurface drip system, with potable (electrical conductivity [EC] = 0.6 dS m−1) or saline (EC = 2.2 dS m−1) water and propagated either early (mid‐March) or late (mid‐June). Establishment rate was calculated on the basis of percentage of green cover, which was determined by means of digital image analysis. At the end of each growing season, root samples were collected and analyzed for root weight density, root length density, and root diameter at three soil depths. When coverage data were averaged over water qualities, plots propagated in 2009 and irrigated from a sprinkler system established fastest, followed by sprinkler‐irrigated plots propagated in 2008. Drip‐irrigated plots were the slowest to reach full coverage. Root length density was higher in sprinkler‐irrigated plots than subsurface drip irrigation plots at all depths. In conclusion, early propagation of Princess 77 bermudagrass resulted in complete coverage with a denser root system at the end of the growing season, regardless of the water quality or irrigation system used. If propagated early, subsurface drip‐irrigated bermudagrass did not require supplemental irrigation from a temporary sprinkler system to successfully establish.

Spatial and Temporal Changes of the Greenery of Colombo City

Plans for landscaping of the City of Colombo are now in place and it is of timely important tostudy the spatial distribution of the vegetation cover and its pattern of change occurredthrough the past to identify the priority areas for restoring and revitalizing the greenery. Thisstudy was therefore focused on mapping the vegetation cover in 47 Wards of the ColomboCity for the years of 1956, 1982, 2001 and 2010 using aerial photographs and IKONOSsatellite maps. The present work was also involved the evaluation of the percentage extents ofvegetation cover and its rates of change in each Ward.According to the resultant maps, a gradual decline of green cover percentage was depicted forthe study period. The green cover of the study area was 35.7%, 32.2%, 31.5% and 22.2% in1956, 1982, 2001 and 2010 respectively. In 2010, the highest green cover (49.65%) wasreported from Narahenpita Ward and only three other Wards (Kirulapona, CinnamonGardens, and Thimbirigasyaya) showed the green cover above 30%. Ten Wards(Kochchikade North, Kochchikade South, Grandpass North, Masangasweediya,Panchikawatte, Fort, Gintupitiya, New Bazar, Maligakanda, Aluthkade East) had green coverless than 10% in 2010.The per capita green cover in 13 Wards did not comply with the World Health OrganizationStandard for urban green spaces. Expansion of built-up areas and road network can beidentified as the major reasons for the gradual reduction of green cover in the City ofColombo.The study also highlights the necessity of a well-planned strategy for upgrading the greencover in the study area. Planting of trees and grasses in public and private lands, increasingpublic awareness on economic value of green spaces as well as implementation of aparticipatory tree maintenance programme would be mandatory for the sustainability of thecity’s greenery.

Sustainable production of fennel (Foeniculum vulgare Mill.) by seed inoculation with mycorrhizae strains under drought stress conditions

In order to study effect of seed inoculation with Mycorrhiza strains on yield of fennel under drought stress conditions a factorial field experiment was carried out at the Research Station of Islamic Azad University, Tabriz Branch, Iran, during 2011-2012 on Fennel (Foeniculum vulgare Mill.) cv. Malayer. Studied factors were irrigation intervals (70mm, 100mm and 130mm evaporation from pan class A) and Mycorrhizae strains (Glomus interadics and G. mosseae). There was a field with non-inoculation with Mycorrhizae as control plot. Mean comparisons revealed that the lowest green cover percentage of fennel (0.13%) could be obtained from noninoculated seeds, but the highest one from those seeds inoculated with G. mosseae. Appearance of leaf senescence symptoms in fennel plants happened earlier when seeds were sown without inoculation. But appearance of these symptoms delayed nearly 5 days. Lower number of secondary branches (8.2 branches) observed in normally irrigated treatment (70mm evaporation from pan). Plants under sever water deficit produced higher seed yield than 100mm evaporation level. Seeds inoculated with G. interadics strain produced higher seed yield (75.25 g m-2) than non-inoculated seeds (55.04 g m-2). Essential oil percentage of fennel seeds only affected by mycorrhizal inoculation treatment, and those seeds inoculated with G. interadics was in a better condition. The stepwise regression analysis verified that the green cover percentage and secondary branches had a marked increasing effect (R2=0.71) on the seed yield of fennel. The present study concluded that seed inoculation with mycorrhizae strains can play a major role in improvement of seed yield in fennel under water deficit conditions.

Biophysical Effects and Ground Force of the Baldree Traffic Simulator

ABSTRACTTraffic simulators are often utilized when researching turfgrass wear tolerance and recovery. However, the availability of a durable traffic simulator capable of producing dynamic force is limited. Therefore, the objectives of this research were to: (i) evaluate a novel traffic simulator with improved durability and capable of producing dynamic force and (ii) evaluate the biophysical effects of the traffic simulator on a native soil turfgrass system. The Baldree traffic simulator is a modified Ryan GA 30 (Jacobsen, A Textron Company, Charlotte, NC) riding aerification unit, equipped with fabricated, spring loaded steel plate feet studded with screw in cleats. The effects of this unit on a ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] system established on a Tifton loamy sand (fine‐loamy, kaolinitic, thermic Plinthic Kandiudults) were evaluated at the Coastal Plains Experiment Station, Tifton, GA. Factors included location (1 and 2) and traffic rate (0, 12, and 24 passes applied over a 6 wk period). Field data included soil bulk density, turf density, and percent green turf cover. An in‐ground force plate at the McPhail Equine Performance Center, East Lansing, MI was used to quantify vertical and net shear ground reaction force produced by the Baldree traffic simulator when operated in the forward and backward direction. The Baldree traffic simulator produced more cleat marks per pass than the Brinkman and Cady traffic simulators. At the low traffic rate the Baldree traffic simulator increased soil bulk density, while turf density and percent green turf cover decreased; therefore, the tool can be used to simulate heavy traffic conditions with a minimum number of passes.

Developmental Response of St. Augustinegrass Cultivars and Experimental Lines in Moderate and Heavy Shade

St. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is considered to be one of the most shade-tolerant warm-season turfgrasses, yet information is lacking on intraspecies developmental responses and performance in shade. This greenhouse study was conducted to 1) compare quality, development, and physiological responses of 10 commercial and experimental lines of st. augustinegrass in moderate and heavy [32% and 15% photosynthetic photon flux (PPF), respectively] shade environments’ and 2) evaluate physiological and morphological indicators that could be used in rapid screening for shade tolerance among st. augustinegrass progeny from a segregating population. A range of shade tolerance was observed between the entries, as noted by quality and percent green cover after 10 weeks of imposed shade conditions. In moderate shade, most entries maintained acceptable (6 or greater) quality and greater than 50% green cover. However, in heavy shade, only ‘Captiva’, ‘Amerishade’, and ‘PI 600734’ maintained acceptable quality, with only PI 600734 and Captiva maintaining greater than 50% cover. ‘TAES 5732-6’, an embryo rescue-derived hybrid from ‘Floratam’, exhibited the least shade tolerance of the group in both shade environments. Neither chlorophyll content nor total nonstructural carbohydrates related well to observed shade quality differences between the entries. A strong correlation existed between shoot elongation rate of a cultivar and its corresponding final percent green cover in moderate shade (R2 = 0.66) but not in heavy shade (R2 = 0.19), suggesting that moderate shade may be the better environment for discriminating genetic differences among st. augustinegrass germplasm for shade tolerance.

Moderate resolution satellite data for mapping salt marshes

Biophysical characteristics of salt marshes are primary indicators of their photosynthetic capacity, nitrogen content, and physiological status. These include the four main characteristics of canopy chlorophyll content: green leaf area index (ratio of green foliage area to ground area), green vegetation fraction (percent green canopy cover), green biomass (which also act as proxies for estimating net primary productivity —NPP), and carbon sequestration potential. Monitoring these characteristics through remotely sensed data can help infer the overall condition and productivity of these valuable natural resources on a larger scale. This would allow effective management strategies in high priority areas. Our research aims to enhance the marsh monitoring practices by including biophysical characteristics (the true early indicators of marsh health status) derived accurately from information such as NASA’s moderate resolution imaging spectroradiometer (MODIS) 250m and 500m data. Our objectives were to calibrate and test a suite of MODISbased vegetation indices (VIs) and develop prototype weekly composites of the salt marsh biophysical characteristics for the entire US Gulf Coast from 2000 to 2010. We then planned to perform a time-series analysis to study the overall trend of salt marsh productivity during the last decade. These VIs (normal difference, wide dynamic range, enhanced, soil-adjusted, etc.) have been widely used and tested for monitoring terrestrial vegetation, but not for salt marsh ecosystems. Our VI calibration and tuning came from establishing relationships between MODIS 250m or 500m data and field data in order to predict the four marsh biophysical characteristics mentioned above. We used atmospherically corrected MODIS 8-day surface reflectance products (250m and 500m), and in situ measurements of biophysical data from 182 locations covering four states (LA, MS, AL, FL). Preliminary analysis revealed that the accuracy of the MODIS-based salt marsh VI calibration depends primarily on three factors: the accuracy of the field data collection, the Figure 1. (a) The dual-headed OceanOptics sensor mounted on a 5m (16ft) high frame. (b, c) Instantaneous field of view (spatial resolution) of the sensor (diameter: 2.2m). (d) In situ sensor calibration.

Summer Percent Green Cover among Kentucky Bluegrass Cultivars, Accessions, and Other Poa Species Managed under Deficit Irrigation

ABSTRACTKentucky bluegrass (Poa pratensis L.) is a widely used, high‐quality, sod‐producing turfgrass. To maintain an acceptable level of quality and function requires irrigation in the semiarid regions of the western United States. Landscape water use, however, is coming under increased scrutiny, and reducing water inputs is a goal of many municipalities. To identify Poa germplasm that maintains green color under deficit irrigation over summer seasons, this study was designed to evaluate the percent of green cover of 24 Kentucky bluegrass cultivars, accessions (including core collections), and other Poa species. Cultivars generally had a higher percent green cover in spring and fall, while several accessions and old U.S. cultivars showed higher green cover during summer months. Other Poa species did not have percent green cover values above any cultivars and as a group consistently performed the lowest. Core collections of Kentucky bluegrass, aimed at representing overall variability of the species with fewer accessions, had variance estimates equal to or higher than the overall group of accessions. Seven cultivars and accessions consistently had higher percent green cover than the Midnight cultivar check during the August data collection dates, highlighting the potential to improve Kentucky bluegrass green cover over summer seasons under deficit irrigation.

Perennial Ryegrass (Lolium perenne L.) and Grooming Affect Bermudagrass Traffic Tolerance

Data describing intraspecific differences in hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] traffic tolerance are limited. Field research was conducted evaluating the effects of mowing practices and perennial ryegrass (Lolium perenne L.) overseeding on the traffic tolerance of three hybrid and one improved common bermudagrass. Bermudagrass cultivars (‘Tifway’, ‘Patriot’, ‘Mississippi Choice’, and ‘Riviera’) were subjected to mowing programs (reel mowing at 2.2 cm [RM] or RM plus grooming to a 1.9 cm depth [RMPG]) and perennial ryegrass overseeding (0 kg pure live seed [PLS] ha−1 or 593 kg PLS ha−1). Simulated traffic was applied twice weekly with a Cady traffic simulator. Percent green cover was measured after each simulated traffic event using digital image analysis. On >70% of evaluation dates, Tifway and Riviera yielded higher percent green cover compared to Patriot, while Mississippi Choice ranked intermediate. Reel mowing at 2.2 cm plus grooming to a 1.9 cm depth reduced percent green cover on the majority of rating dates in 2006; however, this response was not observed in 2007. Reel mowing at 2.2 cm plus grooming to a 1.9 cm depth did not reduce thatch accumulation either year. Reductions in bulk density and increases in green cover, thatch accumulation, and saturated hydraulic conductivity were associated with overseeding, suggesting that this practice may protect bermudagrass athletic fields from both components of traffic stress: wear and soil compaction.

Green-up of Seeded Bermudagrass Cultivars as Influenced by Spring Scalping

Winter dormancy is the main impediment to a wide acceptance of warm-season turfgrasses in the Mediterranean countries of Europe due to a loss of color during the winter months. Scalping during late winter or early spring has been recommended anecdotally to enhance spring green-up of bermudagrass (Cynodon dactylon); however, information is lacking on the effectiveness of this practice. A study was conducted to investigate the effects of spring scalping on spring green-up of eight bermudagrass cultivars (Barbados, Contessa, La Paloma, Mohawk, NuMex Sahara, Princess-77, SR 9554, and Yukon) grown in a transition zone environment. The trial was carried out in Spring of 2009 and 2010 on plots established in July 2005 at the experimental farm of the University of Padova (northeastern Italy). Half of the plots for each cultivar were subjected to spring scalping, which was applied in both years on 13 Mar. with a rotary mower set at a height of 28 mm. Soil temperatures were recorded hourly during the research period at a depth of 2.5 cm. The percentage of green cover was estimated weekly from 0 to 98 days after spring scalping (DASS). Soil temperatures in scalped plots were greater than in unscalped plots. Among the cultivars tested, ‘Yukon’ showed earliest spring green-up, with no difference between the scalping treatments, reaching 80% green cover by the end of April. For all other cultivars, scalped plots reached 80% green cover 10 to 18 days earlier than unscalped plots. Results showed that scalping enhanced spring green-up, primarily for cultivars that recover slowly from winter dormancy.

A simple technique to classify urban locations with respect to human thermal comfort: Proposing the HXG scale

An attempt is made to present a new scale to study urban microclimates and outdoor thermal comfort using simple in-situ measurement data. For this purpose, six urban locations with distinct physical characteristics are selected in a metropolitan city, Chennai. At each location, three streets with diverse orientations (North–south; East–west and Northeast–southwest) are identified and their microclimatic conditions are monitored during the summer months of April, May and June. The variations in microclimate are studied using ANOVA single factor test and later, correlated with the site’s physical characteristics. The assessment of microclimate and outdoor thermal comfort is done using Physiological equivalent temperature (PET). The results show that the site physical factors like the H/W ratio and green cover index show poor and moderate correlations respectively (R 2 of 0.016 and 0.445) when regressed with the mean PET. In this regard the proposed HXG (read as H cross G) scale displays satisfactory correlation (R 2 = 0.648). The HXG scale constitutes a product between the height to width (H/W) ratio and green cover percentage of a location and provides a fair idea about the locality’s microclimatic conditions. This method to study and classify urban microclimates may prove useful in the context of urban design and planning.

Preliminary Findings on the Correlation between Water-soluble Carbohydrate Content in Stolons and First Year Green-up of Seeded Bermudagrass Cultivars

Warm-season grasses are not widely accepted in Mediterranean countries because they lose color during the winter months. A study was conducted at the University of Padova (Padova, Italy) to determine whether fall and spring water-soluble carbohydrate (WSC) content in stolons of seeded bermudagrass cultivars (Cynodon dactylon) influenced spring green-up in the first year of establishment. Nine bermudagrass cultivars (La Paloma, Mohawk, NuMex Sahara, Princess 77, Riviera, SR 9554, Barbados, Contessa, and Yukon) were seeded in July 2005, and dry weight and WSC content in stolons were measured in Fall 2005 and again in Spring 2006. The percentage of green cover and days needed to achieve 80% green cover (D80) were regressed against November and March values of stolon dry weight and WSC content to determine if they were good predictors of D80. ‘Yukon’ showed earliest spring green-up by end of April, and ‘Princess 77’ and ‘Riviera’ were slowest, needing 43 to 46 days more than ‘Yukon’ to reach D80. There was a significant inverse relationship between November (r2 = 0.57) and March (r2 = 0.77) WSC content in stolons and D80 for all nine bermudagrass cultivars. These results suggest that bermudagrass cultivars with high WSC in stolons recover more rapidly from dormancy during establishment than those with low WSC content.

Monitoring of environmental parameters for CO2 sequestration: a case study of Nagpur City, India

Carbon dioxide concentration is an index of total amount of combustion and natural ventilation in an urban environment and therefore required more careful attention for assessment of CO(2) level in air environment. An attempt was made to monitor CO(2) levels in ambient air of Nagpur city at industrial, commercial and residential sites. In addition to this a remote sensing studies and biotic survey for floral biodiversity were carried out to study the green cover at respective sampling locations. The observations showed that the largest amount of CO(2) occurred at night due to absence of photosynthesis and lowest concentration of CO(2) was observed in the afternoon due to photosynthesis at its maximum level. The most pollution tolerant species found in Nagpur city are having higher Air Pollution Tolerance Index (APTI) value, which acts as a natural sink for CO(2) sequestration. In case of commercial site the CO(2) level is highest (366 ppm) because of lowest vegetation and vehicular pollution. The generation of database of CO(2) concentration and floral biodiversity along with percentage of green cover helps to formulate the strategy for prevention of global worming phenomenon.

Batch Analysis of Digital Images to Evaluate Turfgrass Characteristics

Techniques using digital image analysis have been recently developed to evaluate turfgrass stands for percent green cover and average color. Manually analyzing digital images may become cumbersome and tedious if turf field trials contain many plots or if images are collected at frequent intervals for analysis. The objective of the following work was to develop a user‐friendly macro capable of automated batch analysis of an unlimited number of digital images. A macro named “Turf Analysis” was written to batch analyze images using SigmaScan Pro software. The macro, which requires less than 1 min of manual execution, performs percent cover and/or color analysis on an unlimited number of images and automatically saves the results into a spreadsheet file. The macro is freely available to download.

Recovery of Zoysiagrass Varieties from Divot Injury

Although zoysiagrasses (Zoysia japonica Steud., Z. matrella (L.) Merr, and Z. tenuifolia Willd.) provide an excellent golf course fairway or tee surface, their use in areas of intense play may be limited because of their relatively slow recuperative potential. The objective of the following research was to identify zoysiagrass varieties with improved recuperative potential that may be adapted to such situations. Divot injury was simulated in 2003 and 2004 on 24 zoysiagrass varieties maintained under golf course fairway conditions. A digital image of each divot was collected on the day of injury and regularly thereafter until full recovery was reached. Divot images were analyzed for percent green turf cover using digital image analysis to quantify recovery percentages. In both years, 'Crown,' 'Palisades,' and 'Zorro' were among the fastest varieties to recover from injury. 'El Toro' had very rapid recovery in 2003, but not in 2004. 'Meyer' and 'Emerald' were consistently the slowest to recover from injury.

Recovery of Bermudagrass Varieties from Divot Injury

Intensively used turf areas in the southern United States are commonly established to bermudagrass (Cynodon dactylon (L.) Pers. C. dactylon × C. transvaalensis Burtt-Davy), partly due to its good recuperative potential. However, little scientific data is available regarding recuperative differences among bermudagrass varieties. The objective of the following research was to quantify differences in injury recovery among the forty-eight bermudagrass entries in the 2002 National Bermudagrass Test of the National Turfgrass Evaluation Program (NTEP). The trial was maintained under typical golf course fairway conditions and divot injury was simulated in 2003 and 2004. A digital image was collected of each divot on the day of injury and regularly thereafter until full recovery was reached. Divot images were analyzed for percent green turf cover using digital image analysis to quantify recovery percentages. Although divots recovered more quickly in 2004 than in 2003, differences among varieties remained relatively consistent across years. On average, seeded varieties reached 50% recovery one day faster than vegetatively propagated varieties. Among commercially available varieties, ‘La Paloma’ and ‘Yukon’ were fastest to recover while ‘Tifsport’ and ‘Ashmore’ were among the slowest to recover when averaged across years.

Precision and accuracy of eo-1 advanced land imager (ali) data for semiarid vegetation studies

Landsat Thematic Mapper (TM) data and spectral mixture analysis have been used to estimate vegetation green cover in the Great Basin, western United States, to /spl plusmn/4.0% green cover (%GC). In this paper, we compare estimates of percent green cover derived from EO-1 Advanced Land Imager (ALI) data to estimates derived from field-based analyses and to results derived from Landsat Enhanced Thematic Mapper plus (ETM+) data. These analyses define the precision and accuracy of ALI and ETM+ for making quantitative measurements of earth for semiarid ecological studies. The benefits of using ALI were not observed in the calculated uncertainty values (/spl plusmn/5.61%GC and /spl plusmn/6.15%GC for ETM+ and ALI, respectively). However, ALI did not return as many negative green cover estimates and exhibited lower spatial variance in regions of low green cover. These results were attributed to the better signal to noise and data precision inherent to the ALI sensor, and not to the increased number of multispectral bands. ALI was found to be internally inconsistent in that the third sensor chip assembly image swath contained multispectral band coregistration errors. This caused a less than 25%GC error in the ALI estimate of percent green cover along large vegetation gradients.

Modelling forest cover attributes as continuous variables in a regional context with Thematic Mapper data

We modelled forest vegetation attributes as continuousvariables across western Oregon using a multi-image mosaic of Thematic Mapper (TM) data. Four specie c attributes were modelled using regression analysis: percent green vegetation cover, percent conifer cover, conifer crown diameter, and conifer stand age. Reference data for the cover and diameter attributes were derived from airphotos, and existing agency polygon databases were used for stand age. We developed and applied a new method for regional mapping called applied radio- metric normalization. The method involved development of a set of models for a centrally located 'source' scene which were then extended to 'destination' scenes (neighboring scenes in the TM mosaic). Use of airphotos and existing digital databases in combination with applied radiometric normalization translates to a cost-eVective procedure for regional mapping with TM data. Modelling forest attributes as continuous variables enables creation of a e exible forest cover information base, containing important fundamental building blocks for a variety of related classie cation schemes.

Modelling forest cover attributes as continuous variables in a regional context with Thematic Mapper data

We modelled forest vegetation attributes as continuous variables across western Oregon using a multi-image mosaic of Thematic Mapper (TM) data. Four specific attributes were modelled using regression analysis: percent green vegetation cover, percent conifer cover, conifer crown diameter, and conifer stand age. Reference data for the cover and diameter attributes were derived from airphotos, and existing agency polygon databases were used for stand age. We developed and applied a new method for regional mapping called applied radiometric normalization. The method involved development of a set of models for a centrally located 'source' scene which were then extended to 'destination' scenes (neighboring scenes in the TM mosaic). Use of airphotos and existing digital databases in combination with applied radiometric normalization translates to a cost-effective procedure for regional mapping with TM data. Modelling forest attributes as continuous variables enables creation of a flexible forest cover information base, containing important fundamental building blocks for a variety of related classification schemes.