Mu Us Sandy Land (mu + us_sandy_land)

Distribution by Scientific Domains

Selected Abstracts

Rangeland development of the Mu Us Sandy Land in semiarid China: an analysis using Landsat and NOAA remote sensing data

M. C. Runnström
Abstract Degradation of the dry semiarid ecosystems in the Mu Us Sandy Land of north central China was explored using high-resolution satellite images from 1978, 1987 and 1996. This study monitored both changes in grassland biomass production and reclamation activities to detect the nature and scale of land degradation since major economic reforms were introduced in 1978. The position of the high-resolution images within the vegetation cycles was inspected from National Oceanographic and Atmospheric Administration (NOAA) NDVI images at 10-day repetition and seasonal precipitation patterns. A model was developed to categorize changes in the vegetation signal activity from 30,×,30,m pixels into vegetation cover development and land-use changes between 1987 and 1996. A general increase of biomass production was evident despite the rapid increase in numbers of grazing animals. This increase in biomass was confirmed by the NOAA time series, which also revealed annual variability related to the amount and pattern of the seasonal rains. Rangeland conversion to farmland was detected, and this process has increased the area of cultivation almost fivefold. The classified area of cultivation corresponds with reported statistical records, also showing that irrigation features in virtually 100 per cent of the sown area. Signs of declining biological production, indicating land degradation processes, are few. Biomass production has increased, with a gain in the economic output from both crop and animal production. The early start of active measures to halt desertification has increased vegetation cover and lowered wind erosion potential and grasslands seems to be managing the high levels of grazing pressure. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Effects of watering regime and depth of burial on seedling emergence of four dominant psammophytes in the Mu Us sandy land, Inner Mongolia, China, and relevance to revegetation of a desertified region

M.Q. Zheng
Abstract Four dominant psammophyte species are air-seeded in attempts to revegetate the Mu Us sandy land in Inner Mongolia, but seedling emergence is low. This study sought to clarify the behaviour of seedling emergence under different water supply and sand burial regimes to improve the technology of air seeding. Seeds were buried in sand at depths of 0, 0.5, 1, 1.5, 2, 3 and 5 cm and supplied one time with 2.5, 5, 7.5, 10, 15, 20, 30 or 40 mm of water or with 2.5 mm once every 3 days for 30 days. Our study showed that a 0.5-cm burial depth and under 10- to 20-mm single-watering regimes resulted in highest seedling emergence percentage and rate of these four species. All emerged seedlings of Caragana korshinskii, Hedysarum laeve and Artemisia ordosica died under 2.5, 5 and 7.5 mm of watering, respectively, but seedling mortality was <50% when the single-watering regime was >10 mm. In the field, germination of the four species increased from the top of the dune to the middle of the leeward side and then to the bottom. Based on precipitation pattern in the Mu Us sandy land, our study indicates that 0.5-cm burial depth and a single-watering regime of >7.5 mm is the threshold condition for seedling emergence. [source]

Plant species as indicators of the extent of desertification in four sandy rangelands

Ping An
Abstract We examined the distribution of plants in sandy rangelands with different degrees of desertification in (i) Horqin and Mu Us sandy lands in north China, (ii) Darfur district in north-west Sudan and (iii) southern Tunisia. The severity of desertification in these areas was classified as light, moderate, severe or extreme. The following vegetation changes were observed with increasing severity of desertification: a decrease in the number of plant species, an increase in drought-tolerant plants, a decrease in the proportion of palatable grasses and the occurrence of some species in only one category of desertification, whereas other species occurred in several categories. Plant species with unique niche requirements were identified and recommended as indicators of the degree of desertification for particular areas. We discuss the characteristics of species in areas with severe desertification and the method of using plant species as indicators of the extent of desertification. Résumé Nous avons examiné la distribution des plantes dans des régions sableuses touchées à différents degrés par la désertification 1) dans les terres sableuses de Horqin et de Mu Us, dans le nord de la Chine, 2) dans le district du Darfur, au nord-ouest du Soudan et 3) dans le sud de la Tunisie. La gravité de la désertification était classifiée comme légère, modérée, sévère ou extrême. Les changements de végétation suivants ont été observés en fonction de l'accroissement de la désertification: une diminution du nombre d'espèces de plantes, une augmentation des plantes supportant la sécheresse, une diminution de la proportion de plantes appétantes, et l'occurrence de certaines espèces qui ne vivent que dans une catégorie de désertification, alors que d'autres espèces apparaissent dans plusieurs catégories. On a identifié les espèces végétales qui exigent une niche précise et on les a recommandées comme indicateurs du degré de désertification dans des zones particulières. Nous discutons des caractéristiques des espèces dans des régions où la sécheresse est sévère et de la méthode pour utiliser les espèces végétales comme indicateurs de la gravité de la désertification. [source]