Region-specific methods of agriculture were invented fitting in with the local natural resources and developed in the sequence characterized by each of major climo-vegetation types in the world ...(forest, woodland, and grassland/desert), whereas the corresponding region-specific type of desertification occurred if agricultural impacts exceeded the resilience of the natural resources (Shinoda, 2021). In central Eurasia, which is located in the grassland/desert region, nomadic pastoralism has survived for several thousands of years, avoiding an occurrence of serios desertification, whereas the large-scale cereal and irrigated agriculture under the Soviet Union regime led to the region-specific types of desertification such as wind erosion and soil salinization, respectively. As for Mongolia, urgent countermeasures are required to avoid an irreversible degradation of the thousand-year-sustained grassland ecosystem under the overgrazing pressure driven by the market economy.
Human and Desertification SHINODA, Masato
Journal of Arid Land Studies,
2021/09/30, Volume:
31, Issue:
2
Journal Article
Open access
The present review paper outlined the history of how various types of desertification/land degradation were originated regionally, intensified, and spread to a larger area in the agricultural history ...and climate change over the past hundred thousand years. Region-specific methods of agriculture were invented fitting in with the local natural resources and developed in the sequence characterized by each of major climo-vegetation types in the world (forest, woodland, and grassland/desert), whereas the corresponding region-specific types of desertification occurred if agricultural impacts exceeded the resilience of the natural resources. Also, they occurred when the agricultural methods were transferred to different climo-vegetation regions owing to the mismatch with the new environment. Thus, a countermeasure against desertification, that was produced in a climo-vegetation region, is potentially transferable to the same type of region.
Socio-ecological damage from climate-related disasters has increased worldwide, including a type of cold-season disaster (dzud) that is unique to the Eurasian steppes, notably Mongolia. During ...2000-2014, dzuds killed approximately 30 million livestock and impacted the Mongolian socio-economy. The contributions of both natural and social processes to livestock mortality were not previously considered across Mongolia. Here, we consider the contribution of both multiple climate hazards (drought, cold temperatures and snow), and socioeconomic vulnerability (herders' livestock and coping-capacity) to mortality risk. We performed multi-regression analyses for each province using meteorological, livestock and socioeconomic datasets. Our results show that 93.5% of mortality within Mongolia was caused by a combination of multi-hazards (47.3%) and vulnerability (46.2%), suggesting dzuds were both climate- and man-made. However, in high-mortality hotspots, mortality was primarily caused by multi-hazards (drought-induced pasture deficiency and deep-snow). Livestock overpopulation and a lack of coping capacities that caused inadequate preparedness (e.g., hay/forage) were the main vulnerability factors. Frequent and severe multi-hazards greatly increased the mortality risk, while increased vulnerability caused by socioeconomic changes in Mongolia since the 1990s tended to amplify the effects of multi-hazards. Thus, reductions in herder vulnerability within high-mortality hotspots would likely be an effective means of mitigating the risk of future dzuds.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Mongolian pastoral husbandry is subject to various climate hazards such as
dzud
(Mongolian for “severe winter conditions”).
Dzud
in the 2009/2010 winter affected 80.9% of the country and killed more ...than 10 million livestock (23.4% of the total). To understand the natural and man-made mechanisms of this
dzud
, we examined the contributions of
dzud
-causing factors such as climate hazards (cold temperatures and heavy snow) and winter–spring livestock grazing (measured as overgrazing rate), which created a distinct regional pattern of high livestock mortality using a regression tree method. The regression tree model accounted for 58% of the total spatial variation of the mortality and identified various types of
dzud
in each region. Results showed that during the 2009/2010 winter, almost all of Mongolia experienced extreme cold temperatures, with abnormally large amounts of snow. In addition, more than half of the territory was overgrazed because of the lower pasture biomass resulting from summer drought and livestock overpopulation. At the regional scale, high livestock mortalities occurred in moderately to heavily overgrazed regions in south-central and western Mongolia, resulting from the combination of these factors. Conversely, areas with lower livestock mortalities (or non-
dzud
) coincided with sufficient pasture capacity in the north and east, even under extreme cold and snow. This indicates the importance of controlling the number of livestock to below the pasture carrying capacity regardless of an inter-annually varying climate. Moreover, we identified critical thresholds of each factor across which serious disasters occurred. These thresholds are practically useful for future livestock management of pasture land.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Drought is among the highest-impact natural hazards affecting drylands around the world in a warming climate. The Mediterranean region, including Tunisia, is projected to experience the most ...predominant drying trends worldwide. However, a detailed regional scale study of drought for Tunisia has been limited, hampering an assessment of drought impact on the ecosystem and society. This study explored drought characteristics and its effect on vegetation greenness and agricultural productivity in three vegetation zones of Tunisia during 1982–2011, taking advantage of both meteorological and soil moisture drought indices and identifying the most appropriate index for each zone. The results revealed that meteorological droughts were short and frequent, triggering soil moisture droughts that were long-lasting and intense. The standardized precipitation index was identified as the best indicator of vegetation and agricultural droughts in the Northern forest, while the Palmer Drought Severity Index was best in the Central steppe and Southern desert (no crop data in the Southern desert). The lag-correlation analysis revealed that the response of both vegetation greenness and wheat productivity to droughts was more pronounced and had a longer significant lag in the Central steppe than in the other regions. These results suggest that arable land species (Central steppe and Southern desert), characterized by shallow roots, have a rapid response to rainfall variability when compared with forest species (Northern forest), which have deep roots allowing them an adequate supply of moisture. The region-specific indices identified here will provide a useful measure for drought monitoring and mitigation in Tunisia.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Drought frequency, duration, and severity and its impact on pasture productivity in the four main vegetation zones of Mongolia were analyzed using meteorological, soil moisture, and vegetation data ...during the growing season (April–August) of 1965–2010. Meteorological and pasture drought characteristics were explored using the Standardized Precipitation Index (SPI), the soil moisture anomalies percentile index (
W
p
), and Palmer Drought Severity Index (PDSI) on 1-month timescale. Generally, 35–37 (15–16 %) by SPI for meteorological drought while 27–29 (12–13 %) by
W
p
, and 16–21 (7–9 %) by PDSI for pasture drought with different durations were identified over the four vegetation zones during the study period. Most of these droughts (80 % by SPI and 50–60 % by both
W
p
and PDSI) observed during the entire events occurred on a 1-month duration with moderate intensity. Drought frequencies were not significantly (
p
> 0.05) different within the four zones. The frequency of the short-term meteorological droughts was observed relatively greater than pasture droughts; however, pasture droughts were more persistent and severe than meteorological droughts. The three indices show that the frequency and severity of droughts have slightly increased over the 46 years with significant (
p
< 0.05) dry conditions during the last decade of 2001–2010 in the four zones (except in the high mountain). The results showed the
W
p
was more highly significantly correlated with the precipitation anomalies (
r
= 0.68) and pasture production (
r
= 0.55) than PDSI (
r
= 0.51,
p
< 0.05 and
r
= 0.38,
p
< 0.10, respectively). A statistical model, based on pasture production and the
W
p
, suggested that the consecutive drought months contribution during the growing season was 30 % (
p
< 0.05) and that pasture production was more sensitive to the occurrence of droughts during June–August (
R
2
= 0.32,
p
< 0.05) as seen in 2000–2002 and 2007. We concluded that a greater severity and frequency of growing-season droughts, during the last decade of 2001–2010, have driven a reduction in pasture production in Mongolia.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Wind erosion results in soil redistribution and textural changes on topsoil. There is little information about how these changes affect plant production. Here, we compared simulations of vegetation ...growth between a wind-eroded scenario and an actual condition at two sites in Mongolian grasslands (steppe and desert steppe) using an ecosystem model. The wind-eroded scenario, topsoil (0–0.1 m depth) with 1% clay and 99% sand, was designed to represent an extremely wind-eroded soil surface that had permanently lost the fine particles and gained sand particles. Effects of temperature, nutrient, and water stresses on vegetation were quantitatively estimated. The model gave reasonably good simulations of the vegetation and soil water dynamics. Results show that water had more effect on plant production than nitrogen and temperature. In the wind-eroded scenario, stresses because of a lack of water and nutrients affected plant production. For the wind-eroded topsoil, plant production decreased (20.2%) in the desert steppe with increasing water stress, but it was slightly increased (5.0%) in the wetter steppe because of an inverse texture effect, where water infiltrates from the coarse topsoil to the deeper root-zone due to lower soil evapotranspiration and facilitates growth. Plant growth was, therefore, affected by the nitrogen supply.
•Wind-eroded coarse topsoil effect on plant in two Mongolian grasslands is studied.•A wind-eroded scenario and an actual condition of topsoil are used for simulation.•Effects of temperature, nitrogen and water on plant for two cases are compared.•Water and nitrogen stresses more affect plant growth in the wind-eroded topsoil.•Higher production for wind-eroded topsoil in steppe due to inverse texture effect.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A decadal change in the frequency of dust outbreaks for April over East Asia using World Meteorological Organization (WMO) synoptic data was identified. The causes of the decadal change can be ...defined in terms of aeolian erosivity (i.e., ability of wind to cause erosion represented by wind speed) and erodibility (i.e., susceptibility of soil and land surface to wind erosion represented by the threshold wind speed for dust outbreak). Dust outbreak frequency (fDO) increased at many stations in Mongolia, Inner Mongolia, northeastern China, and the Hexi Corridor from the 1990s to the 2000s. Especially, remarkable increases were observed for Mongolia. Strong wind frequency (fu>ut5%) decreased or changed little over the period of study, and the 5th percentile of the threshold wind speed for dust outbreak (ut5%) decreased at many stations in Mongolia, eastern Inner Mongolia, and northeastern China. This suggests changes in erodibility factors increased fDO in these regions. There are stations where fu>ut5% increased and ut5% remained relatively constant in western Inner Mongolia and the Hexi Corridor. This suggests changes in the erosivity factor increased fDO at these locations. The change in erodibility is linked, in part, to the effect of dead leaves of grasses in spring, which are the residue of vegetation in summer from the previous year, which can cause an increase in the threshold wind speed.
Key Points
Dust outbreaks increased by changes in erodibility in Mongolian grasslands
Dust outbreaks increased by changes in erosivity in deserts
Thre are areas where dead leaves affect erodibility in Mongolian grasslands
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Asian windblown dust events cause human and animal health effects and agricultural damage in dust source areas such as China and Mongolia and cause “yellow sand” events in Japan and Korea. It is ...desirable to develop an early warning system to help prevent such damage. We used our observations at a Mongolian station together with data from previous studies to model the spatial distribution of threshold wind speeds for dust events in northeast Asia (35°–45°N and 100°–115°E). Using a map of Normalized Difference Vegetation Index (NDVI), we estimated spatial distributions of vegetation cover, roughness length, threshold friction velocity, and threshold wind speed. We also recognized a relationship between NDVI in the dust season and maximum NDVI in the previous year. Thus, it may be possible to predict the threshold wind speed in the next dust season using the maximum NDVI in the previous year.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A method is proposed to estimate the threshold wind speed for dust emissions as a function of soil moisture in arid regions. This method, which is applicable at the local scale, employs a model of ...the surface heat budget to estimate the spatial distribution of thermal inertia-derived soil moisture (TISM) and an analytical footprint model to estimate dust source areas. It incorporates readily available satellite and meteorological data. The soil moisture inside the dust source area is estimated for individual dust phenomena observed at a synoptic surface observation site, and then, together with the corresponding observed wind speed, the threshold wind speed as a function of soil moisture is found by employing the parametrization of Fécan et al. (Ann Geophys 17:149–157, 1999). This relationship represents the local dust climatology at the observation site, although the data include some outliers. The results show that readily available data for the natural environment can be used, as an alternative to wind-tunnel data, with the parametrization used to derive the threshold wind-speed relation. The derived relation indicates the TISM and wind speed at which the probability of a dust phenomenon is 10%. Moreover, the threshold wind-speed results are not sensitive to the principal footprint-model parameters. The TISM standard error of approximately 0.04 m
3
m
−3
could significantly affect the results under dry and weak-wind conditions, but this sensitivity can be avoided if the soil clay content or the soil type at the observation point is known.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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