Climate change, drought and desertification

Houérou, Henry Noël Le

doi:10.1006/jare.1996.0099

Cited by 470 publications

(266 citation statements)

References 123 publications

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“…Here, for descriptive purposes, Category S is divided into S w , S m , and S s , according to weak, medium, and strong degradation condition, respectively. Soil degradation also occurs in humid climates (Le Houerou 1996). In order to omit land degradation areas in wet climates, including densely populated urban areas, pixels with an AI greater than 0.65 were not used.…”

Section: Category S (Soil Degradation Areas)mentioning

confidence: 99%

“…However, there has been no prior systematic study on the identification of soil degradation areas (including desert areas) at a global scale, because it is difficult to distinguish degradation areas from semi-arid regions in which droughts occur frequently. Drought reduces plant growth; however, if the drought ends and rainfall returns, plant growth recovers to its former level, whereas soil degradation has a long-lasting effect with permanent and sometimes irreversible consequences for production (Le Houerou 1996). Therefore, in order to distinguish desert areas, areas where droughts occur frequently, and soil degradation areas, it is necessary to investigate the long-term variations in NDVI observations.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Category S (Soil Degradation Areas)mentioning

confidence: 99%

Section: Introductionmentioning

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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“…Although there is no general agreement regarding future rainfall regimes, enhanced summer drought and water deficit in the Mediterranean ecosystems are projected, as it has already occurred in the last decades (Le Houérou 1996;Piñol et al 1998;De Luís et al 2001;Peñuelas et al , 2005Peñuelas and Boada 2003;IPCC 2007).…”

Section: Introductionmentioning

confidence: 99%

Effects of experimental warming and drought on biomass accumulation in a Mediterranean shrubland

et al. 2009

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We studied the effects of experimental warming and drought on the plant biomass of a Mediterranean shrubland. We monitored growth at plant level and biomass accumulation at stand level. The experimentation period stretched over 7 years (1999)(2000)(2001)(2002)(2003)(2004)(2005) and we focused on the two dominant shrub species, Erica multiflora L. and Globularia alypum L. and the tree species Pinus halepensis L. The warming treatment increased shoot elongation in E. multiflora, and the drought treatment reduced shoot elongation in G. alypum. The elongation of P. halepensis remained unaffected under both treatments. The balance between the patterns observed in biomass accumulation for the three studied species in the drought plots (reduction in E. multiflora and P. halepensis and increase in G. alypum) resulted in a trend to reduce 33% the biomass of the drought treatment plots with respect to the untreated plots, which almost doubled their biomass from 1998 to 2005. The results also suggest that under drier conditions larger accumulation of dead biomass may occur at stand level, which combined with higher temperatures, may thus increase fire risk in the Mediterranean area.

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“…Such extreme events can have disastrous consequences for human society due to resulting famine and disease, soil degradation, desertification, and increased incidence of wildfires (di Castri and Mooney, 1973;Le Houérou, 1996). Since the major rivers of Turkey provide water for adjacent countries of the Middle East, fluctuations in Turkey's precipitation and streamflow can have wide-ranging geopolitical consequences.…”

Section: Introductionmentioning

confidence: 99%

Tree‐ring reconstructions of precipitation and streamflow for north‐western Turkey

Akkemik

D’Arrigo

Cherubini

et al. 2007

Intl Journal of Climatology

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ABSTRACT:We describe tree-ring reconstructions of spring (May-June) precipitation and spring-summer (May-August) streamflow for north-western Turkey, both beginning in AD 1650. These are among the first such reconstructions for the region, and the streamflow reconstruction is among the first of its kind for Turkey and the entire Middle East. The reconstructions, which both emphasize high-frequency variations, account for 34 and 53% of their respective instrumental variance. Comparison to precipitation and runoff data provides some means of verification for the instrumental streamflow record, which is very short (30 years). Drought and flood events in the reconstructions are compared to historical archives and other tree-ring reconstructions for Turkey. The results reveal common climatic extremes over much of the country. Many of these events have had profound impacts on the peoples of Turkey over the past several centuries.

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Climate change, drought and desertification

Cited by 470 publications

References 123 publications

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

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

Effects of experimental warming and drought on biomass accumulation in a Mediterranean shrubland

Tree‐ring reconstructions of precipitation and streamflow for north‐western Turkey

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