Climate change has led to more frequent extreme winters (aka, dzud) and summer droughts on the Mongolian Plateau during the last decade. Among these events, the 2000-2002 combined summer drought-dzud and 2010 dzud were the most severe on vegetation. We examined the vegetation response to these extremes through the past decade across the Mongolian Plateau as compared to decadal means. We first assessed the severity and extent of drought using the Tropical Rainfall Measuring Mission (TRMM) precipitation data and the Palmer drought severity index (PDSI). We then examined the effects of drought by mapping anomalies in vegetation indices (EVI, EVI2) and land surface temperature derived from MODIS and AVHRR for the period of 2000-2010. We found that the standardized anomalies of vegetation indices exhibited positively skewed frequency distributions in dry years, which were more common for the desert biome than for grasslands. For the desert biome, the dry years (2000-2001, 2005 and 2009) were characterized by negative anomalies with peak values between −1.5 and −0.5 and were statistically different (P < 0.001) from relatively wet years (2003, 2004 and 2007). Conversely, the frequency distributions of the dry years were not statistically different (p < 0.001) from those of the relatively wet years for the grassland biome, showing that they were less responsive to drought and more resilient than the desert biome. We found that the desert biome is more vulnerable to drought than the grassland biome. Spatially averaged EVI was strongly correlated with the proportion of land area affected by drought (PDSI < −1) in Inner Mongolia (IM) and Outer Mongolia (OM), showing that droughts substantially reduced vegetation activity. The correlation was stronger for the desert biome (R 2 = 65 and 60, p < 0.05) than for the IM grassland biome (R 2 = 53, Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. 1 1748-9326/13/035033+12$33.00 c 2013 IOP Publishing Ltd Printed in the UK Environ. Res. Lett. 8 (2013) 035033 R John et al p < 0.05).Our results showed significant differences in the responses to extreme climatic events (summer drought and dzud) between the desert and grassland biomes on the Plateau.
Ecosystems in the Central Asian Plateau, which includes the Mongolian Plateau, are becoming increasingly sensitive to human interventions, leading to deterioration of already fragile ecosystems. The goal of this paper is to illustrate human dependence on an ecosystem by identifying patterns of resource consumption in this region and investigating the knowledge and perceptions of herders living in these ecosystems. Data on consumption in the two regions were collected using structured questionnaires delivered to a total of 252 herders from Mongolia and China's Inner Mongolia. Meat and other animal products remain the dominant food items for most households, accompanied by various vegetables and cereals. This unbalanced diet leads to excessive consumption of protein and fat from animal sources. The major energy sources used by herders are fuelwood, animal dung, crop residues, and dry grass, but consumption patterns differed between the two areas. Mongolian herders rely more heavily on livestock for meeting their consumption needs than herders in Inner Mongolia. Herder knowledge and perceptions of ecosystem conditions and consumption of resources differed between Mongolia and Inner Mongolia, reflecting the influence of different state policies. The data reported and the conclusions drawn are relevant for developing resource management policies for the Mongolian Plateau, but also provide useful insights for any region where livestock production dominates the use of rangeland resources.
Remotely sensed land surface temperature- (LST-) dependent evapotranspiration (ET) models and vegetation index- (VI-) LST methods may not be suitable for ET estimation in energy-limited cold areas. In this study, the relationship of ET to LST was simulated using the process-based Simultaneous Heat and Water (SHAW) model for energy- and water-limited conditions in Mongolia, to understand the differences in ET processes under these two limiting conditions in dry and cold climates. Simulation results from the SHAW model along with ground observational data showed that ET and LST have a positive relationship when air temperature (Ta) is less than or equal to the temperature (Ttra) above which plants transpire and have a negative relationship whenTais greater thanTtraunder the energy-limited condition. However, ET and LST maintain a negative relationship with changes inTaunder the water-limited condition. The differences in the relationship between ET and LST under the energy-limited and water-limited conditions could be attributed to plant transpiration and energy storage in moist/watered soil and plants. This study suggests that different strategies should be used to estimate ET under the energy-limited condition in dry and cold climates.
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