Characteristics of desertification and its rehabilitation in China

Zha, Yong; Gao, Jay

doi:10.1006/jare.1997.0290

Cited by 108 publications

(92 citation statements)

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“…Although the area of afforestation is increasing rapidly as a result of the above-mentioned projects, the area of degraded land has continued to expand and the severity of desertification has continued to intensify throughout the country (16). This suggests that these costly efforts have yielded little success thus far; deserts in China have expanded to cover an additional 1560 km 2 of land every year from 1950 to 1975, 2100 km 2 /yr from 1976 to 1988, and 3600 km 2 /yr after 1998 (4,15,17). Accompanying this desertification, sandstorms have increased in frequency and intensity in recent years in northern China, from an average of 0.5 times per year in the 1950s to 10.3 times per year between 2000 and 2006 ( Figure 2; 4, [14][15][16][17][18][19].…”

Section: Failure Of Large-scale Afforestation Effortsmentioning

confidence: 99%

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Why Large-Scale Afforestation Efforts in China Have Failed To Solve the Desertification Problem

Cao¹

2008

Environ. Sci. Technol.

377

243

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Traditional Chinese approaches to ecosystem restoration have focused on afforestation as an important tool for controlling desertification. However, the long-term results of this practice increasingly show that these projects are actually increasing environmental degradation in arid and semiarid regions, with ecosystems deteriorating and wind erosion increasing. Rather than focusing solely on afforestation, it would be more effective to focus on re-creating natural ecosystems that are more suitable for local environments and that can thus provide a better chance of combating desertification.Arid and semiarid regions make up ~40% of the earth's land surface and are home to ~20% of the human population, but these areas are increasingly being affected by desertification (1). A half-century policy of forest exploitation, livestock overgraz- SHIXIONG CAO CHINA AGRICULTUR AL UNIVERSITYTrenches were dug parallel to the contours during planting to prevent downslope erosion and collect slope runoff for the trees. The decreased vegetation cover can offset this advantage by increasing wind erosion.

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Section: Failure Of Large-scale Afforestation Effortsmentioning

confidence: 99%

“…Currently, desertification is concentrated in the northwestern, northern, and northeastern parts of the country (the so-called Three Norths): an estimated 3.3 million km 2 have been affected by desertification, accounting for 34% of China's total land area (4).…”

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Why Large-Scale Afforestation Efforts in China Have Failed To Solve the Desertification Problem

Cao¹

2008

Environ. Sci. Technol.

377

243

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“…Sandification is a related term that refers to land degradation in sandy areas, involving aeolian erosion, windblown sands, shifting dunes and the encouragement of sands into agriculture and even inhabited areas [1,2]. Certainly, sandification processes are associated with vegetation deterioration, productivity reduction, unstable ecosystems, environmental detriment and economic loss.…”

Section: Introductionmentioning

confidence: 99%

Spatio-Temporal Dynamics of Land-Use and Land-Cover in the Mu Us Sandy Land, China, Using the Change Vector Analysis Technique

Karnieli

Qin

et al. 2014

Remote Sensing

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Abstract:The spatial extent of desertified vs. rehabilitated areas in the Mu Us Sandy Land, China, was explored. The area is characterized by complex landscape changes that were caused by different drivers, either natural or anthropogenic, interacting with each other, and resulting in multiple consequences. Two biophysical variables, NDVI, positively correlated with vegetation cover, and albedo, positively correlated with cover of exposed sands, were computed from a time series of merged NOAA-AVHRR and MODIS images (1981 to 2010). Generally, throughout the study period, NDVI increased and albedo decreased. Improved understanding of spatial and temporal dynamics of these environmental processes was achieved by using the Change Vector Analysis (CVA) technique applied to NDVI and albedo data extracted from four sets of consecutive Landsat images, several years apart. Changes were detected for each time step, as well as over the entire period (1978 to 2007). Four categories of land cover were created-vegetation, exposed sands, water bodies and wetlands. The CVA's direction and magnitude enable detecting and quantifying finer changes compared to separate NDVI or albedo difference/ratio images OPEN ACCESS Remote Sens. 2014, 6 9317 and result in pixel-based maps of the change. Each of the four categories has a biophysical meaning that was validated in selected hot-spots, employing very high spatial resolution images (e.g., Ikonos). Selection of images, taking into account inter and intra annual variability of rainfall, enables differentiating between short-term conservancies (e.g., drought) and long-term alterations. NDVI and albedo, although comparable to tasseled cap's brightness and greenness indices, have the advantage of being computed using reflectance values extracted from various Landsat platforms since the early 1970s. It is shown that, over the entire study period, the majority of the Mu Us Sandy Land area remained unchanged. Part of the area (6%), mainly in the east, was under human-induced rehabilitation processes, in terms of increasing vegetation cover. In other areas (5.1%), bare sands were found to expand to the central-north and the southwest of the area.

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“…The threshold value of AI (0.65) is the same as for the subhumid zone used in the World Atlas of Desertification (Middleton andThomas 1992, 1997). Equations defining the three subcategories are as follows: Areas of severe land degradation in China coincide with the regions in the desertification map described by Zha and Gao (1997). In Australia, Kimberley Plateau, Tanami D, and Barkly Tableland from west to east fall under Category S. In the Americas, most of the Great Basin D, Great Plains from 30…”

Section: Category S (Soil Degradation Areas)mentioning

confidence: 99%

Classification of arid lands, including soil degradation and irrigated areas, based on vegetation and aridity indices

Gamo

Shinoda

Maeda

2013

International Journal of Remote Sensing

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It is preferable to prepare internally consistent maps of arid regions on a global scale in order to understand the present conditions of arid regions, especially deserts and soil degradation areas. We attempted to delimit arid regions at a global scale by combining climate data, i.e. aridity index (AI), and vegetation data, i.e. vegetation index. The annual AI was estimated by the ratio of mean annual precipitation to mean annual potential evapotranspiration, using the Thornthwaite method. The long-term mean of yearly maximum normalized difference vegetation index (NDVI ymx ) was used as an indicator of the vegetation condition. Arid regions of the world were classified into four categories, namely A, severe deserts, where both aridity and vegetation indices are very small; G, semi-arid regions, where the vegetation index is proportionally related to the AI; I, irrigated areas and oases, where the vegetation is relatively abundant despite severe dryness; and S, soil degradation areas, where the vegetation is poor despite relatively humid conditions. The Sahel from Niger to Chad, the Sahel in Darfur, and the Ordos Plateau in China are within Category S. The standard deviation of NDVI ymx is very small/large in severe deserts/semi-arid areas, respectively. Thus, the Sahara desert was clearly distinguished from the Sahel; the latter belongs to Category G and drought occurs frequently here. In Category S zones, the standard deviation of NDVI ymx is relatively small compared with that within the Category G zone because the return rainfall does not seem to promptly restore productivity. Category S was divided into three subdivisions according to the degree of degradation, expressed by the ratio of the AI to vegetation index. Category G was also divided into four classes, according to degree of vegetation (or aridity). The distribution of Category S is comparable to the soil degradation areas mapped by Global Assessment of Human-Induced Soil Degradation (GLASOD) data. True deserts, where the standard deviation of NDVI ymx is very small, were selected from the 'severe desert' group. Desert areas were classified as true deserts, severe deserts, grassland deserts (Category G), and soil degradation deserts (Category S).

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Characteristics of desertification and its rehabilitation in China

Cited by 108 publications

References 0 publications

Why Large-Scale Afforestation Efforts in China Have Failed To Solve the Desertification Problem

Why Large-Scale Afforestation Efforts in China Have Failed To Solve the Desertification Problem

Spatio-Temporal Dynamics of Land-Use and Land-Cover in the Mu Us Sandy Land, China, Using the Change Vector Analysis Technique

Classification of arid lands, including soil degradation and irrigated areas, based on vegetation and aridity indices

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