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Habitat quality for many wildlife populations has a spatial component related to the arrangement of habitat elements across large geographic areas. With remote sensing and GIS technology, this paper presents an approach to calculate Habitat Suitability Index (HSI) for Giant Pandas to evaluate the habitat quality. In this paper, a buffer of a given distance (30 km or more) to the Giant Panda distribution area estimated in three national surveys (1974, 1989 and 2002), which is located in Sichuan, Gansu and Shanxi provinces in western China, was used as the study area. In order to study different species group’s habitat quality, the study area is divided into five parts: the Qinling mountain systems, located in the southeast in Shanxi province, the Minshan mountain systems, located in the south in Gansu province and northwest in Sichuan province, the Qionglai mountain systems, the Xiangling mountain systems and the Liangshan mountain systems, located in the west of Sichuan province, conforming to the five big Giant Panda species groups. Three physical environmental factors (elevation, slope and aspect), one ecological factor (vegetation distribution) and several human-influence factors (distances to highways, general roads, inhabitants and rural areas) are selected as the influence factors to calculate HSI. Each factor was reclassified by grid-cell (30 × 30 m per cell) to the suitability index scale from 0 to 1 based on habitat affinities before final calculation. After analyzing the HSI values on the most Giant Panda distribution area, 0.0144 was considered as the threshold habitat quality. Then, HSI was calculated for five mountain systems for three periods conforming to three national surveys (1974, 1989 and 2002). Several benefits to the approach can be highlighted. Firstly, HSI can be used as the standard to evaluate the quality of Giant Panda habitat. Secondly, by using HSI maps from 1974, 1989 and 2002, we can see that the Giant Panda habitat was the largest in 1974, and was then reduced much before 1989. However, by 2002, it had recovered to some extent, which conforms to the habitat data from the three national surveys. Thirdly, the habitat changes in the five mountain systems examined in the study are different. Finally, nature reserves play an important role in the protection of Giant Panda habitat; there are more suitable habitats in nature reserves than non-protected areas.
Shrub development on road outside verges can provide alternative wildlife habitat. However, management of inside verges should keep vegetation at a height consistent with proper road visibility and safety. The influence of management on vegetation was analyzed on the inside verge of two Portuguese roads, one mown once and another twice a year. Specifically, the effect of mowing frequency on shrub abundance and the combined effect of management and shrubs on floristic diversity were addressed. One stretch of each road was surveyed for shrub abundance and for herbaceous species diversity and cover. The effect of mowing frequency on shrub growing and biomass production and allocation was also evaluated along two years. Results indicate that vegetation mowing yearly in spring is enough to keep the inside verge free from most shrubs. However, summer growing shrubs like Dittrichia viscosa can persist, decreasing both floristic diversity and cover, particularly of meadow species. Moreover, in response to spring mowing, shrubs grew fast and were able to disperse efficiently. An additional autumn mowing significantly decreased not only shrub height and canopy area, but specially seed production and dispersal. Thus, the inside verge management should be based on two mowing periods. The first in spring to control winter and spring growing species, and an additional autumn mowing to control growth and dispersal of summer growing shrubs and trees, or even tall grasses. This management regime will combine safety with improvement of the amenity and habitat value of the road verges.
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