Monitoring Vegetation Change Research Articles

Monitoring vegetation changes in Al Madinah, Saudi Arabia, using Thematic Mapper data

Abstract An exemplary approach using Landsat Thematic Mapper data is presented, which allows us to monitor vegetation changes under the aspects of urban planning in Saudi Arabia. As a test site, the city of Al Madinah was chosen. TM data of two different acquisition dates were merged via intensity/ hue/saturation (IHS) processing to present directly the bi-temporal variations within one image product. The image product is analysed in terms of geoscientific application and its significance is discussed. Finally, how the method presented could be integrated into a possible operational vegetation monitoring system of selected regions in Saudi Arabia, is outlined.

時系列植生指数データのフーリエ解析

In this paper, Fourier analysis is applied to multitemporal global vegetation index (GVI) data forextracting the parameters which represent the GVI monthly change. The monthly GVI data is prepared by selecting maximum value in pixels of weekly GVI data for removing cloud effect. The averaged monthly GVI data is made by averaging monthly GVI data through 3 years (April 1982-March 1985), and are used for Fourier analysis. The phase of the first order, the power spectrum of the main, the first, the second and the third order are calculated. It is found that the phase of the first order is used for finding the peak of the monthly NVI data and can be used for monitoring the variation of the season. The usefulness of the power spectrum map of each order and the phase map of the first order is also shown. The paper indicates that these parameters will be used for monitoring vegetation change yearly.

Stable isotope ratios of carbon in phytoliths as a quantitative method of monitoring vegetation and climate change

The 13C/ 12C ratios of occluded carbon within opal phytoliths from the northern Great Plains show potential as a basis for paleoclimatic reconstruction. A significant correlation exists between the carbon isotopic composition of a host plant and that of the organic matter in its phytoliths. The 13C/ 12C ratios for phytoliths from surface layers of soils along climatic gradients reflect the current proportions of C 3 and C 4 plants. Variations in the δ 13C values of phytoliths with soil depth are caused by a variety of processes: burial of soil surface by dust, bioturbation, and possible illuviation by percolating water. Also, contributions of phytoliths by dust and roots have unknown isotopic effects. The δ 13C values of phytoliths from soils increase with decreasing 14C age, suggesting that the proportion of C 4 plants in this region has increased during the Holocene. Phytoliths of apparent mid-Holocene age suggest exclusive dominance by C 4 plants which agrees with paleoclimatic interpretations of an arid middle Holocene climate.

Recovery after Wildfire: Warm Temperate Rainforest at Jones Creek, East Gippsland, Victoria

Summary Approximately 80 ha of warm temperate rainforest in far East Gippsland was severely burnt in February 1983. A study to assess the impact of a wildfire commenced under the National Rainforest Conservation Programme in 1987. Seventy seven permanent Quadrats were established on a grid to monitor vegetation changes, and the numbers and areas occupied by trees, shrubs and seedlings were determined. Five years after the fire, the vegetation composition was dominated by species which characterise mature rainforest. Large increases also occurred in the populations of Acacia melanoxylon, Eucalyptus sp., sclerophyll shrubs and a number of disturbance dependent herbs. Rainforest species recovered through both seedlings and epicormic sprouts. Few species were obligate seed regenerators and these included species restricted to early regeneration stages, as well as uncommon rainforest overstorey species. Populations of several epiphytic species uncommon before the fire may have been reduced, and Cyathea leichhardtiana, a tree fern with restricted distribution in East Gippsland, may have to re-establish from spores. It was concluded that earlier fires had influenced the species composition of the rainforest and contributed to its invasion by sclerophyll species. This invasion had been greatly extended by the most recent fire. The distribution and abundance of the sclerophyll overstorey is considered likely to increase with each successive disturbance by fire until eucalypts dominate the area entirely. The future fire regime will also determine the composition of the understorey. An interval between fires of less than 40–50 years is likely to cause a progressive decline in the proportion of rainforest species, with the rate determined by both frequency and intensity of burning.

A weighted key species method for monitoring changes in species composition of Highland Sourveld

The use of key species for indexing veld condition in relation to the fire/grazing impact has potential for monitoring change in the Highland Sourveld of Natal. Weightings are calculated for previously identified key species. A weighted-averages approach is used in a modified weighted key species method of indexing veld condition. Veld condition indices calculated using the method are highly correlated with rankings along a previously identified grazing gradient (r = 0, 85). Weightings are provided for indicator species that can be generally used for monitoring vegetation changes in the Highland Sourveld. The method has the advantage of being able to determine the position of a sample site on a grazing gradient, and thereby make inferences as to the grazing/burning history of the site.Language: EnglishKeywords: botany; burning; condition indices; grazing gradient; grazing history; highland sourveld; indicator species; key species; method; monitoring; natal; ordination; range condition; Range conditions; south africa; species composition; vegetation change; vegetation changes; veld condition

Changes in Vegetation Associated with the Removal of Prairie Dogs

From 1938 to 1982 the total acreage of Black-tailed prairie dog (Cynomys ludovicianus) towns in Wind Cave National Park increased from 290 to 750 ha. In 1982 a management plan was introduced that reduced the area covered by prairie dog towns to 290 acres. The objective of this study is to monitor vegetation changes that occur following the removal of prairie dogs. These data will prove useful in developing management plans for the removed prairie dog towns and also provide useful data on the vegetation and seed bank composition on the Wind Cave National Park grasslands.

Vegetation cover mapping from NOAA/AVHRR

The visible and near infrared channels, Ch 1 and CH 2 respectively, on the Advanced Very High Resolution Radiometer (AVHRR) provide daily information for monitoring changes in vegetation and crops. Data from these channels are used to create a normalized vegetation index (NVI) that is sensitive to changes in green leaf biomass and is represented mathematically by: NVI = CH 2 − CH 1 CH 2 + CH 1 Operational products generated at NOAA include full-scale 1-km resolution images of the NVI covering areas viewed in a single swath of the polar-orbiting NOAA satellite. Global scale NVI images are also produced by compositing over a seven-day period, saving the maximum NVI created daily for each local array (resolution of 15 km at the equator to 30 km at the poles). Such seven-day mapping reduces the effect of cloud contamination. The global vegetation indices are used by foreign and U.S. government agencies for operational and experimental purposes such as assessment of crop conditions, monitoring potential desert locust breeding grounds, forest fire danger models, and monitoring range lands for forage availability. Examples include changes in the NVI in the Lake Chad vicinity, 1981–1982 and 1984; western United States NVI; and seasonal variations of the NVI in the Sahel using the global operational data base, 1982–1983.