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Agricultural drought events have become more frequent in the Inner Mongolia inland river basin in recent years, and the spatio-temporal evolution characteristics and development rules can be accurately and comprehensively understood using the three-dimensional identification method. In this paper, standardized soil moisture index (SSMI) was used to characterize agricultural drought, and modified Mann–Kendall trend test (MMK) and 3D recognition of drought events were used to analyze the spatio-temporal evolution characteristics of agricultural drought events in this basin and reveal the drought development law. The relationships between drought and temperature (T), precipitation (P), evapotranspiration (E), and humidity (H) were analyzed using a cross-wavelet method. The results are as follows: (1) When the time scale of agricultural drought was short (monthly scale), the alternations of dry and wet were frequent, but the SSMI index of all scales showed a downward trend; (2) The spatial distribution characteristics of drought change trend in four seasons were similar, but the area with a significant downward trend of drought in spring was the largest, and the area of high frequency region was also the largest, and the drought trend was the most obvious; (3) The most serious agricultural drought event occurred from October 2000 to May 2002, and reached its maximum value in September 2001 (drought area and drought severity of 2.26 × 105 km2 and 3.61 × 105 months·km2, respectively), which mainly experienced five processes—drought onset–intensification–decay–re-intensification–termination—and the migration path of the drought center showed the characteristics of southwest–northeast transmission; (4) All the four meteorological factors were correlated with SSMI, and P had a greater impact on SSMI. This article aims to reveal the spatio-temporal evolution of agricultural drought events in the Inner Mongolia inland river basin, and provide a new way to accurately evaluate the spatio-temporal evolution of drought. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Agrometeorology is the property of Editorial Board of Chinese Journal of Agrometeorology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Drought refers to a meteorological disaster that results in insufficient soil moisture due to a long-term lack of rainfall and disrupts the moisture balance of crops. Yinshanbeilu in Inner Mongolia is an arid and semi-arid region, and the onset of drought and its subsequent transmission is a key challenge in water resource management. This study takes Yinshanbeilu as the study area, analyses the changing characteristics of multi-timescale drought from 1971 to 2020 based on the Standardised Precipitation Index (SPI), and analyses the stochasticity and stability of the drought by using a cloud model. Finally, the cross-wavelet transform method and Pearson's test are used to explore the correlation between atmospheric circulation factors, PRE and PET, and drought. The results indicate that (1) on the annual scale, the frequency of drought in Yinshanbeilu mainly ranges from 22% to 28%, with a high frequency of light droughts, a low frequency of severe droughts, a high frequency of droughts in the east and west, and a low frequency of droughts in the north and south; on the seasonal scale, the frequency of droughts in winter is the highest, with a rate of 34.6%, and the lowest frequency of droughts is in autumn, with a rate of 28.3%. (2) There is a decreasing trend in Entropy (En) and Hyper-Entropy (He), and an increasing trend in Expectation (Ex) for the inter-annual SPI-12 cloud model. Spatially, Ex and He are negatively correlated, while En and He are positively correlated. The inter-annual variation in cloud eigenvalues is greater than the inter-site variation, so the cloud model better reflects the spatial stochasticity and stability of regional inter-annual SPI. For the seasonal-scale SPI-3 cloud model, Ex is smaller in all seasons, En is also smaller, and He is larger. (3) Sunspot, PRE (precipitation), and PET (Potential Evapotranspiration) are all positively correlated with SPI and have the highest correlation. This study reveals the characteristics and causes of variations of drought in Yinshanbeilu, which can be applied to future research areas related to regional drought risk management. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Driven by continuously evolving precipitation shifts and temperature increases, the frequency and intensity of droughts have increased. There is an obvious need to accurately monitor drought. With the popularity of machine learning, many studies have attempted to use machine learning combined with multiple indicators to construct comprehensive drought monitoring models. This study tests four machine learning model frameworks, including random forest (RF), convolutional neural network (CNN), support vector regression (SVR), and BP neural network (BP), which were used to construct four comprehensive drought monitoring models. The accuracy and drought monitoring ability of the four models when simulating a well-documented Inner Mongolian grassland site were compared. The results show that the random forest model is the best among the four models. The R2 range of the test set is 0.44–0.79, the RMSE range is 0.44–0.72, and the fitting accuracy relationship could be described as RF > CNN > SVR ≈ BP. Correlation analysis between the fitting results of the four models and SPEI found that the correlation coefficient of RF from June to September was higher than that of the other three models, though we noted the correlation coefficient of CNN in May was slightly higher than that of RF (CNN = 0.79; RF = 0.78). Our results demonstrate that comprehensive drought monitoring indices developed from RF models are accurate, have high drought monitoring ability, and can achieve the same monitoring effect as SPEI. This study can provide new technical support for comprehensive regional drought monitoring. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a framework for evaluating the performance of ecosystem strategies prepared for enhancing vulnerability reduction in the face of hazards due to climate change. The framework highlights the positive effects of human activities in the coupled human and natural system (CHANS) by introducing adaptive capacity as an evaluation criterion. A built-in regional vulnerability to a certain hazard was generated based upon interaction of three dimensions of vulnerability: exposure, sensitivity and adaptive capacity. We illustrated the application of this framework in the temperate farming-grazing transitional zone in the middle Inner Mongolia of the northern China, where drought hazard is the key threat to the CHANS. Specific indices were produced to translate such climate variance and social-economic differences into specific indicators. The results showed that the most exposed regions are the inner land areas, while counties located in the eastern part are potentially the most adaptive ones. Ordos City and Bayannur City are most frequently influenced by multiple climate variances, showing highest sensitivity. Analysis also indicated that differences in the ability to adapt to changes are the main causes of spatial differences. After depiction of the spatial differentiations and analysis of the reasons, climate zones were divided to depict the differences in facing to the drought threats. The climate zones were shown to be similar to vulnerability zones based on the quantitative structure of indexes drafted by a triangular map. Further analysis of the composition of the vulnerability index showed that the evaluation criteria were effective in validating the spatial differentiation but potentially ineffective because of their limited time scope. This research will be a demonstration of how to combine the three dimensions by quantitative methods and will thus provide a guide for government to vulnerability reduction management. [ABSTRACT FROM AUTHOR]

The increasing frequency of global drought events poses a significant threat to the stability of grassland ecosystems' functionality. The Inner Mongolian grasslands stand out as one of the world's most drought-prone regions, facing elevated drought risks compared to other biomes. An in-depth comprehension of the impact of drought on grassland ecosystems is paramount for their long-term sustainability. Using the Standardized Precipitation Evapotranspiration Index (SPEI) from 1982 to 2018, this study identified various drought events within the Inner Mongolian grasslands, encompassing moderate drought, severe drought, and extreme drought. The resistance of the vegetation to the different drought conditions, assessed through net primary productivity (NPP) as a metric (reflecting its capacity to maintain its original level during drought periods), was examined. The research findings indicated that the period from 2001 to 2018 witnessed a substantial increase in both the frequency and the extent of drought events compared to the period from 1982 to 2000, particularly concerning severe and extreme droughts. The areas most severely impacted by extreme drought were the Xilingol League and the Alxa League. From 1982–2000 to 2001–2018, under moderate drought conditions, vegetation resistance exhibited a minor decrease in the central and eastern regions but experienced a slight increase in the western region. In contrast, under severe drought conditions, the western region saw a significant decrease in vegetation resistance. Remarkably, under extreme drought conditions, the western region showed a substantial increase in vegetation resistance, while the central and eastern regions experienced a slight decrease. Across all three drought conditions, as precipitation levels declined, the resistance of the meadow–steppe–desert ecosystems demonstrated a high–low–high distribution pattern. The temperate desert steppe exhibited a minimal vulnerability to drought, boasting resistance levels exceeding 0.9. Notably, extreme drought had the most pronounced impact on the temperate meadow steppe, temperate steppe, and temperate desert steppe, particularly within the temperate meadow steppe category. Given these findings, the authorities responsible for grassland management should prioritize regions characterized by frequent drought occurrences and low drought resistance, such as Ulanqab City, the Xilingol League, and the western part of Hulun Buir City. Safeguarding steppe ecosystems is of paramount importance for stabilizing vegetation productivity and land carbon sinks, especially under the anticipated exacerbation of climate conditions in the future. [ABSTRACT FROM AUTHOR]

Background: Nitrogen- and water-use efficiency (NUE and WUE) reflect the capacity of plants to take up and utilize resources in the environments. Although N deposition and drought are known to affect plant growth and persistence, it remains elusive how plants adjust NUE, WUE and their relationship to adapt to the concurrent N deposition and drought under the context of global change. We conducted a field experiment in a temperate grassland in Inner Mongolia, in which N addition (10 g m–2 yr−1), drought (reduced 66% precipitation during growing season) and their combination were manipulated, and we explored the responses of both instantaneous (NUEINST and WUEINST) and long-term (NUELT and WUELT) WUE and NUE for six common plant species (Leymus chinensis, Stipa baicalensis, Thermopsis lanceolata, Potentilla bifurca, Thalictrum squarrosum, Klasea centauroide). Results: Across all the six species, NUEINST decreased and WUEINST increased with both N addition and drought; NUELT decreased with both N addition and drought, while WUELT decreased with N addition and increased with drought. A significant interactive effect between N addition and drought was detected, in that, drought weakened the negative effect of N addition on WUELT and NUELT, and N addition weakened the negative effect of drought on NUELT, but enhanced the positive effect of drought on WUELT. As a consequence, drought caused a trade-off between NUE and WUE, and N addition brought forth positive correlation between NUE and WUE. Meanwhile, the relationship between NUE and WUE varied among the species of different functional groups. Conclusions: Our study demonstrated that NUE, WUE and their relationship play an important role in determining their responses and adaptability to changes in soil nitrogen and water availability induced by N deposition and drought. Our results shed light on the antagonistic, synergetic and neutral effects between nitrogen deposition and drought on resource use efficiency, and further clarified the different adaptability among species of different functional groups, which will conduce to a comprehensive understanding on the role of NUE and WUE in plant persistence and coexistence in grassland ecosystems. [ABSTRACT FROM AUTHOR]

In the context of global warming, timely and accurate drought monitoring is of great importance to ensure regional ecological security and guide agricultural production. This study established the Drought Severity Index (DSI), based on the potential evapotranspiration (PET), evapotranspiration (ET) and normalized difference vegetation index (NDVI) data from 2001 to 2020, to compensate for the low accuracy of drought spatial and temporal evolution due to the uneven distribution of stations. The DSI index was established to reveal the spatial and temporal variation of droughts in Inner Mongolia in the past 20 years, using trend analysis, gravity shift and geographic probes, and to explore the influence of different factors on the DSI. The results were as follows. (1) The results showed that the spatial distribution of DSI in Inner Mongolia during 2001–2020 had strong spatial heterogeneity, and generally showed distribution characteristics of drought in the west and wet in the east. In addition, the changes in DSI all exhibited a rising tendency, with the highest tendency in deciduous broadleaf forests (DBF) and the lowest tendency in grassland (GRA). (2) The center of gravity of wet, normal and arid areas showed a migration trend from northeast to southwest, with migration distances of 209 km, 462 km and 826 km, respectively. (3) The four combinations of temperature and elevation, temperature and slope, temperature and land use, and temperature and rainfall contributed the most. The results obtained in this study are important for the scheduling of ecological early warnings and drought prevention and control. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the past few decades, drought has been a frequent phenomenon in many parts of the world, especially in arid and semi-arid regions. Hence in order to better predict the development trend of drought in Inner Mongolia and formulate corresponding countermeasures for disaster prevention and mitigation, for this paper we calculated the aridity index according to the annual mean precipitation and temperature data of 109 stations covering 1961-2010. The study result indicated that the mean aridity degree was increasing from west to east and was mainly characterized by moderate aridity; from 1961 to 2010 the change of aridity has been decreasing while aridity has been increasing, especially after the abrupt changing point in 1995. Moreover, the decreasing area of aridity took up 82.6% while the increasing area only occupied 17.4% of the whole area. During a 50-year time scale, the annual mean aridity oscillation periodicity was at 49a, 25a, and7a, and Inner Mongolia was still at a stage of aridity that might last for a long time. Regarding different decades, the climate of Inner Mongolia was relatively humid in the 1980s; however, as time went by the area of moderate aridity degree increased while the humidity area decreased in the early 21st century. Therefore, it was clear that the climate was becoming drier year after year. From 1960 to 2010, contours lower than 30 shifted toward longitude direction and contours more than 30 moved in the direction of latitude. [ABSTRACT FROM AUTHOR]

The dynamics of plants' carbon and water use efficiency and their responses to drought are crucial to the sustainable development of arid and semi-arid environments. This study used trend analysis and partial correlation analysis to examine the carbon use efficiency (CUE) and water use efficiency (WUE) of Inner Mongolia's vegetation from 2001 to 2020. MODIS data for gross primary productivity (GPP), net primary productivity (NPP), potential evapotranspiration (PET), evapotranspiration (ET), drought severity index (DSI), and plant type were used. Altered trends were observed for drought during 2001–2020 in the study area. The results revealed that 98.17% of the research area's drought trend was from dry to wet and 1.83% was from wet to dry, and the regions with decreased drought regions were broadly dispersed. In 2001–2020, CUE in Inner Mongolia declined by 0.1%·year−1, whereas WUE reduced by 0.008 g C·mm−1·m−2·year−1, but the total change was not significant. CUE decreased from west to east, whereas WUE increased from southwest to northeast. DSI and CUE had the highest negative connection, accounting for 97.96% of the watershed area, and 71.6% passed the significance test. The correlation coefficients of DSI and WUE were spatially opposite to those of CUE and DSI. In total, 54.21% of the vegetation cover exhibited a negative connection with DSI. The CUE and WUE of different vegetation types in Inner Mongolia were negatively correlated with the DSI index except for grasslands (GRA). Drought in Inner Mongolia mostly influenced the CUE of different plant types, which had a higher negative correlation than WUE. The study's findings can inform climate change research on Inner Mongolia's carbon and water cycles. [ABSTRACT FROM AUTHOR]

The characteristics of vegetation and drought for different seasons between 1982 and 2015 in Inner Mongolia were studied based on the normalized difference vegetation index (NDVI) and the standardized precipitation evapotranspiration index (SPEI). The response of vegetation to drought over various timescales for different seasons and vegetation types was investigated using the maximum Pearson correlation, allowing a discussion about the possible causes of any changes. The results indicate that the vegetation NDVI in Inner Mongolia showed an increasing trend in different seasons, with spring vegetation NDVI (April–May) having the largest significant increasing rate, followed by the growing season (April–October), autumn (September–October), and summer (June–August). Accordingly, the proportion of stations with decreasing SPEI was, in descending order, summer, growing season, autumn, and spring. Additionally, the magnitude of the SPEI decrease was greater in eastern Inner Mongolia. NDVI and SPEI were positively correlated in most regions of Inner Mongolia, indicating that changes in vegetation in most parts of this region were affected by the spatial and temporal characteristics of drought, the correlation being them being strongest in the growing season, followed by summer, then spring and autumn. Considering the different types of vegetation, forests were less affected by drought, with broadleaf forests more affected than coniferous forests. The meadow steppes and typical steppes were more affected by 12‐month droughts in the growing season and summer, 6‐month droughts in spring, and 3‐month droughts in autumn, with desert steppes mainly affected by 3‐month droughts. The shrubs, sandy vegetation, and cropland were mostly affected by droughts in summer, and show a greater response to 3‐month droughts in autumn. Finally, the water balance was found to be the most important factor affecting the response of vegetation to drought in Inner Mongolia. [ABSTRACT FROM AUTHOR]

• The efficiency of Sentinel-3A SLSTR LST and NDVI was proved in monitoring agricultural drought. • VTCI can only be used in warm seasons (late spring and summer) to conduct agricultural drought monitoring. • VTCI was encouraging as a near-real-time drought monitoring indicator. Agricultural drought is one of most damaging agricultural hazards worldwide that can bring significant agricultural losses and water scarcity. The use of satellite images for monitoring agricultural drought has received increasing research attention and has also been applied at both the regional and global scales. In this paper, the land surface temperature (LST) and radiance products of the new Sentinel-3A SLSTR (sea and land surface temperature radiometer) launched by European Space Agency (ESA) are used for the first time for estimating the vegetation temperature condition index (VTCI), which in turn is used for monitoring agricultural drought in the Hetao Plain of Inner Mongolia, China. This paper initially analyzes the correlation between LST and normalized difference vegetation index (NDVI) by using time series time MODIS LST and NDVI products under different vegetation growth conditions. The findings reveal that VTCI can only be used in warm seasons (late spring and summer periods) when negative correlations between LST and NDVI are observed. Therefore, VTCI images are captured in the study area between July and August 2017 by using Sentinel-3A SLSTR LST and NDVI and are utilized for drought investigation. These images reveal that the average VTCI of the cultivated land pixels in the study area has increased from 0.4511 on July 28 to 0.5229 on August 12 before declining to 0.4710 on August 18 due to the rainfall in the first period, thereby indicating that VTCI has a timely response to rainfall. Meanwhile, cross-comparison of VTCI values from Sentinel-3A SLSTR shows high consistency in terms of spatial distribution with that estimated from EOS MODIS products. The difference between these indices ranged from −0.1 to 0.1 for most points, especially in the cultivated land cover. Overall, the findings support the use of the LST and NDVI products of Sentinel-3A SLSTR in monitoring agricultural drought. [ABSTRACT FROM AUTHOR]

Ecosystem water use efficiency (eWUE) can be used to obtain a better comprehension of the ecosystem water-carbon cycle. This study aimed to characterize the regional-scale responses and adaptations of different vegetation categories to drought changes and the spatiotemporal characteristics of WUE and associated drought factors for nine vegetation categories in Inner Mongolia, China, from 2000 to 2020. This study estimated drought, the association between drought and eWUE among varying vegetation categories, and the differences in eWUE between the drought stage and the post-drought stage by analyzing the spatiotemporal variations in eWUE of different vegetation categories based on MODIS ET (evapotranspiration), GPP (gross primary productivity), and temperature vegetation drought index data. The results illustrated the following: (1) the multi-year mean eWUE from 2000 to 2020 was 1.03 g·m−2·mm−1, with an overall significantly increasing trend of 0.008 g·m−2·mm−1 and eWUE decreasing from northeast to southwest. (2) The rank of vegetation types in Inner Mongolia according to multi-year mean eWUE was evergreen coniferous forest > savanna > evergreen broadleaf forest > forested grassland > farmland > deciduous broadleaf forest > mixed forest > closed scrub > grassland. All vegetation categories illustrated an increasing trend in eWUE over time. (3) eWUE was inversely associated with drought in the drought stage and a clear effect of drought legacy was identified in which harsh drought impacted the eWUE of the ecosystem, whereas eWUE was positively associated with drought. (4) The eWUE values of ecosystems increased significantly after drought, indicating that ecosystems that are adapted to drought show high capacity to recovery from drought stress. [ABSTRACT FROM AUTHOR]

The arid and semiarid grassland ecosystems are characterized by limited water resources and are generally vulnerable to climate change. Understanding how plants in arid and semiarid ecosystems respond to global climatic variation is crucial for ecological restoration under a changing climate. Although the effects of climate on aboveground biomass (AGB) and belowground biomass (BGB) have been widely explored, how AGB and BGB respond to climatic variation is seldom disentangled. There is still a need to understand how plant communities respond to global climate change. In this study, we conducted a transect survey across grasslands in Inner Mongolia to capture changes in AGB and BGB in plant communities. Then, we used structural equation modelling (SEM) to explore the relationship between environmental factors and the root:shoot ratio to understand how plant communities respond to ecological drought under global climate change. Our results showed that low precipitation use efficiency (LPUE) results in a high root:shoot (HRS) ratio, and BGB was more sensitive to environmental changes. By contrast, high precipitation use efficiency (HPUE) led to a low root:shoot (LRS) ratio, and environmental factors had a greater impact on AGB. For the LPUE pattern, soil water content (SWC), pH, and soil total nitrogen (STN) mainly affected the HRS ratio. Soil water content and STN influenced the HRS ratio through a positive effect on BGB. For the HPUE pattern, SWC, STN, and plant abundance (PA) predominantly regulate the LRS ratio, while biodiversity (plant abundance) affects the LRS ratio by positively affecting AGB. Our results highlight the differential impact of precipitation use efficiency on aboveground and belowground biomass allocation. This is important for monitoring the impact of drought events on plant biomass, improving productivity assessment models in arid and semi‐arid regions, and assessing local carbon storage accurately. [ABSTRACT FROM AUTHOR]

Knowledge gain in the characteristics and mechanisms of drought propagation is indispensable for timely drought early warning and risk reduction over the grassland eco-region. This study focused on the Xilin River basin, which is a typical inland river basin located in the Inner Mongolia temperate steppe, China. The characteristics of meteorological and hydrological drought were assessed by applying the standardized precipitation index and standardized streamflow index. The propagation relationship between meteorological and hydrological droughts was then investigated from both static and dynamic perspectives, and the possible reasons for its temporal dynamics were discussed by considering environmental factors. Our results showed that the Xilin River basin has suffered from more serious meteorological drought than hydrological drought during the past 60 years, with a stationary evolution of meteorological drought but an overall drying trend in hydrological drought. The propagation from meteorological to hydrological droughts exhibited obvious seasonality, characterized by stronger intensity and shorter response time in the wet season. Nonstationary behaviors were identified for the temporal patterns of drought propagation time, especially showing a significant trend in April, May, and August. The dynamic changes in propagation time affected by regional forces were principally ruled by the precipitation variation positively and strongly, and they were moderately controlled by temperature, vegetation cover, and deep-layer soil moisture, with season-dependent effects. The effects of low-frequency atmospheric anomalies on drought propagation will be further investigated in future studies, which are expected to provide a better understanding of the physical mechanism of the large-scale climate forcing on local drought condition. Significance Statement: A new research approach was proposed to assess the propagation relationship between meteorological and hydrological drought from both static and dynamic perspectives, and the possible reasons for the temporal dynamics were discussed by considering environmental factors. Focusing on an inland river basin over the Inner Mongolia typical steppe, the propagation from meteorological to hydrological droughts showed obvious seasonality. Nonstationary behaviors were identified for the temporal patterns of drought propagation time, which could be explained by the regional hydrometeorological conditions. The advanced understanding of drought propagation provides a scientific base for water resources planning and drought management within a grassland region. [ABSTRACT FROM AUTHOR]

Inner Mongolia (IM) is one of the five major pastoral areas in China, and animal husbandry is its traditional industry. The population of livestock is an important factor affecting the sustainable development of livestock and grassland. Due to the special geographical location of IM, various meteorological disasters occur frequently, which have a significant impact on the local livestock population. In this study, principal component analysis (PCA) and geographically weighted principal component analysis (GWPCA) were used to explore the spatial and temporal patterns of small livestock and large livestock populations in county-level administrative units from 2000 to 2020, and the effects of meteorological disasters on livestock populations were also considered. We found that the cumulative proportion of total variance (CPTV) of the first two principal components of global PCA for small livestock and the first principal component for large livestock reached 94.54% and 91.98%, respectively, while the CPTV of GWPCA was in the range of 93.23–96.45% and 88.47–92.49%, respectively, which showed stronger spatial explanation; the small livestock population was significantly correlated with spring drought, summer drought, spring–summer drought and snow disaster. However, the correlation between large livestock and summer drought and spring–summer drought is greater. We conclude that GWPCA can better explain the spatial change of livestock populations; meteorological disasters have both advantages and disadvantages on the livestock population, and the drought types that have a greater impact on livestock are summer drought and spring–summer drought. There are geographical differences in the impact of meteorological disasters, with drought affecting most of IM and snow disaster mainly affecting the eastern region; large livestock were mainly affected by drought, while small livestock were affected by both drought and snow disaster. [ABSTRACT FROM AUTHOR]

The accuracy of drought monitoring models is crucial for drought monitoring and early warning. Random forest (RF) is being used widely in the field of artificial intelligence. Nonetheless, the application of a random forest model in grassland drought monitoring research is yet to be further explored. In this study, various drought hazard factors were integrated based on remote sensing data, including from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Global Precipitation Measurement (GPM), as multisource remote sensing data. Based on the RF, a comprehensive grassland drought monitoring model was constructed and tested in Inner Mongolia, China, as an example. The critical issue addressed is the construction of a grassland drought disaster monitoring model based on meteorological data and multisource remote sensing data by using an RF model, and the verification of the accuracy and reliability of its monitoring results. The results show that the grassland drought monitoring model could quantitatively monitor the drought situation in Inner Mongolia grasslands. There was a significantly positive correlation between the drought indicators output by the model and the standardized precipitation evapotranspiration index (SPEI) measured in the field. The correlation coefficients (R) between the drought degree were 0.9706 and 0.6387 for the training set and test set, respectively. The consistent rate between the model drought index and the SPEI reached 87.90%. Drought events in Inner Mongolia were monitored from April to September in wet years, normal years, and dry years using the constructed model. The monitoring results of the model constructed in this study were in accordance with the actual drought conditions, reflecting the development and spatial evolution of drought conditions. This study provides a new application method for the comprehensive assessment of grassland drought. [ABSTRACT FROM AUTHOR]

Questions: Drought timing during the growing season can profoundly influence plant diversity and cover, with subsequent impacts on ecosystem functions and services in terrestrial environments. However, the different responses of plant communities to drought in different periods of the growing season remain uncertain. Location: The research was conducted in a semi‐arid grassland at the Duolun Restoration Ecology Research and Demonstration Station, in Inner Mongolia, China. Methods: The responses of plant species richness and cover to early‐ and late‐season drought with a four‐year field experiment were examined in a semi‐arid grassland in northern China. Soil moisture at different depths was measured to explore the underlying mechanisms of the drought effects on plant richness and cover. Results: Over the four years, late‐ rather than early‐season drought suppressed plant richness. Decreased species richness (−1.65 species) under late‐season drought was mainly due to suppressed perennial forb richness (−1.88 species). Late‐season drought also exerted greater negative effects on plant cover than early‐season drought. Effects of late‐season drought on plant cover depended on annual precipitation. Reduced plant cover (−7.5%) under early‐season drought stemmed from declines in shrubs and semi‐shrubs, particularly Artemisia frigida cover (−4.9%), which is sensitive to water deficits because of its shallow root depth (14.01 cm). Declined plant cover (−39.0%) under late‐season drought was mainly caused by suppressed perennial forb (−21.5%) and shrub and semi‐shrubs cover (−17.4%). The combined effects of early‐ and late‐season drought on plant cover were greater than the treatment alone, likely due to aggravating water deficits under growing‐season drought. Conclusions: Our results suggest late‐season drought is more critical for shifting plant communities. than early‐season drought. Our findings highlight the regulatory role of drought timing on plant community composition and development in arid and semi‐arid regions. [ABSTRACT FROM AUTHOR]

Under global warming, according to results obtained from offline drought indices driven by projections of general circulation models (GCMs), future droughts in China will worsen but the results are not consistent. We analyzed changes in droughts covering the entire hydrologic cycle using outputs of GCMs of the 6th Coupled Model Intercomparison Project (CMIP6) for SSP2-4.5 and SSP5-8.5 climate scenarios, and compared the results with that of popular, offline drought indices [the self-calibrating Palmer Drought Severity Index (scPDSI), Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Precipitation Actual Evapotranspiration Index (SPAEI)]. Among meteorological, agricultural, and hydrological drought indices tested under both SSP scenarios, the results obtained from SPAEI and scPDSI agree better with univariate drought indices than SPEI. scPDSI generally agrees well with agricultural droughts (Standardized Soil Moisture Index with the surface soil moisture content; SSIS). Future droughts estimated using soil moisture analysis are more widespread than that from precipitation and runoff analysis in humid regions of South China by the end of the twenty-first century. In arid northwestern China and Inner Mongolia, drought areas and severity based on scPDSI and SSIS forced with the SSP scenarios show obvious decreasing trends, in contrast to increasing trends projected in South China. Trends projected using SPEI contradict those projected by other drought indices in non-humid regions. Therefore, selecting appropriate drought indices is crucial in project representative future droughts and provides meaningful information needed to achieve effective regional drought mitigation strategies under climate warming impact. [ABSTRACT FROM AUTHOR]

Drought events cause ecological problems, including reduced water resources and degraded vegetation. Quantifying vegetation responses to drought is essential for ecological management. However, in existing research, the response relationships (correlations and lags) were typically determined based on Pearson correlation coefficient and the resultant lag times were constrained by the spatial and temporal resolutions of the analyzed data. Inner Mongolia is an important ecological barrier in northern China. Ecological security is one of the most concerned issues of the region's sustainable development. Herein, we combined Global Inventory Modeling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI3g) with Systeme Probatoire d'Observation de la Terra-vegetation (SPOT-VGT) NDVI data through spatial downscaling. The obtained 1 km-resolution NDVI dataset spanning Inner Mongolia from 1982 to 2019 was used to represent the refined vegetation distribution. The standardized precipitation evapotranspiration index (SPEI) derived from gridded meteorological data was used to measure drought over the same period. We investigated the spatiotemporal characteristics of vegetation and drought in the region in the past 38 years. We then discussed changes in different vegetation responses to drought across eastern Inner Mongolia using cross wavelet transform (XWT) and wavelet coherence (WTC). The results reveal that in 82.4% of the study area, NDVI exhibited rising trends, and the SPEI values exhibited declining trends in 78.5% of the area. In eastern Inner Mongolia, the grassland NDVI was positively correlated with SPEI and significantly affected by drought events, while NDVI in forestlands, including shrubs, broad-leaved forests, and coniferous forests, was negatively correlated with SPEI in the short term and weakly affected by drought. The NDVI lag times behind SPEI in grasslands, coniferous forests, and broad-leaved forests were 1–1.5, 4.5, and 7–7.5 months, respectively. These findings provide a scientific foundation for environmental preservation in the region. [ABSTRACT FROM AUTHOR]

Climate conditions can significantly alter the vegetation net primary productivity (NPP) in many of Earth's ecosystems, although specifics of NPP–climate condition interactions, especially time-lag responses on seasonal scales, remain unclear in ecologically sensitive forest–grassland ecotones. Based on the Moderate-Resolution Imaging Spectroradiometer (MODIS) and meteorological datasets, we analyzed the relationship between NPP and precipitation, temperature, and drought during the growing season (April–August), considering the time-lag effect (0–5 months) at the seasonal scale in Hulunbuir, Inner Mongolia, China from 2000 to 2018. The results revealed a delayed NPP response to precipitation and drought throughout the growing season. In April, the precipitation in the 4 months before (i.e., the winter of the previous year) explained the variation in NPP. In August, the NPP in some areas was influenced by the preceding 1~2 months of drought. The time-lag effect varied with vegetation type and soil texture at different spatial patterns. Compared to grass and crop, broadleaf forest and meadow exhibited a longer legacy of precipitation during the growing season. The length of the time-lag effects of drought on NPP increased with increasing soil clay content during the growing season. The interaction of vegetation types and soil textures can explain 37% of the change in the time-lag effect of the NPP response to PPT on spatial pattern. Our findings suggested that preceding precipitation influences vegetation growth at the early stages of growth, while preceding drought influences vegetation growth in the later stages of growth. The spatial pattern of the time lag was significantly influenced by interaction between vegetation type and soil texture factors. This study highlights the importance of considering the time-lag effects of climate conditions and underlying drivers in further improving the prediction accuracy of NPP and carbon sinks in temperate semiarid forest–grassland ecotones. [ABSTRACT FROM AUTHOR]

Drought has been approved to affect the process of terrestrial ecosystems from different organizational levels, including individual, community, and ecosystem levels; however, which traits play the dominant role in the resistance of plant to drought is still unclear. The experiment was conducted in semi-arid temperate grassland and included six paired control and drought experimental plots. The drought treatment was completely removed from precipitation treatments from 20 June to 30 August 2013. At the end of the growing season in 2013, we removed the rain cover for ecosystem recovery in 2014. The results demonstrated that drought treatment increased the coverage of and abundance Heteropappus altaicus, Potentilla bifurca, and Artemisia scoparia by 126.2–170.0% and 63.4–98.9%, but decreased that of Artemisia frigida, Dontostemon dentatus, and Melissilus ruthenicu by 46.2–60.2% and 49.6–60.1%. No differences in coverage and abundance of Agropyron cristatum, Stipa kiylovii, and Cleistogenes squarrosa were found between control and drought treatment. The coverage and abundance of Stipa kiylovii have exceeded the original level before the drought stress, but Heteropappus altaicus still had not recovered in the first year after the disturbance. Our findings indicate that plant functional traits are important for the understanding of the resistance and resilience of plants to drought stress, which can provide data support for grassland management. [ABSTRACT FROM AUTHOR]

Vegetation is an indicator of changes in the ecological environment and a key source of feedback on the impact of drought. In this work we selected northern China as the study area and used the standardized precipitation evapotranspiration index (SPEI) and the normalized difference vegetation index (NDVI) to assess the relationship between drought and vegetation dynamics at annual and seasonal scales for the period 1982–2015. The results indicated that annual drought showed a slight increase in northern China during this time, and it was mainly attributed to the intensified summer drought; the percentages of areas where significant drying, drying, wetting, and significant wetting occurred accounted for 3.30%, 53.36%, 40.39%, and 2.95%, respectively. Annual NDVI showed a highly significant (p < 0.01) upward trend in northern China, suggesting that vegetation there is greening. However, there was still a significant decrease in the NDVI trend in 13.65% of the study area, and forest accounted for the greatest area among the three land cover types studied. A positive correlation between annual SPEI and annual NDVI was found in most of northern China, and 18.66% of the study area (p < 0.05) were mainly distributed in the central-eastern part of Inner Mongolia, the central part of the Loess Plateau, and northwestern part of Xinjiang Province. Residual analysis found that the percentages of vegetation dynamics affected by human-induced degradation, human-induced improvement, and drought accounted for 13.91%, 47.91%, and 38.18%, respectively; however, 54.15% of the areas affected by drought were located in arid and semi-arid regions and that about 54.61% of those were grassland. The work could provide guidance for vegetation construction and water resource management in northern China. [ABSTRACT FROM AUTHOR]

As an essential part of the hydrological cycle, precipitation is usually associated with floods and droughts and is increasingly being paid attention to in the context of global warming. Analyzing the change trends and correlation of temperature and extreme precipitation indicators can effectively identify natural disasters. This study aimed to detect the correlation and change trends of temperature and extreme precipitation indicators in Inner Mongolia from 1960 to 2019. Panel vector autoregression (PVAR) models based on Stata software were used to detect the correlation between temperature and extreme precipitation indicators at 35 climatological stations throughout Inner Mongolia. The temperature and extreme precipitation indicator trends were analyzed using the Mann–Kendall test and Sen's slope method. The spatial distribution characteristics of the annual precipitation and rainfall intensity were more significant in the southeast and more minor in the northwest, while an increase in the annual wet days was noticeable to the northeast. The Granger cause tests of the temperature and the extreme precipitation indicators showed a correlation between each indicator and temperature at the significance level of 1%. The temperature positively correlated with only the rainfall intensity while negatively correlating with the remaining indicators. There is no doubt that trend analysis showed significant increasing trends in rainfall intensity at all stations, which means increased risk in extreme precipitation events. By contrast, the annual precipitation and annual wet days showed significant decreasing trends, which means that the precipitation is concentrated, and it is easier to form extreme precipitation events. The study can provide a basis for decision-making in water resources and drought/flood risk management in Inner Mongolia, China. [ABSTRACT FROM AUTHOR]

Background and Aims: Global changes (precipitation changes and nutrient deposition) profoundly impact structure and function of steppe ecosystem. However, it is unclear the mechanism by which multiple limiting resources affect plant aboveground net primary productivity (ANPP) in desert steppe. Methods: We conducted a field experiment manipulating both precipitation (3 levels: ambient and ± 50% precipitation) and nutrients addition (3 levels: ambient; nitrogen (N) addition; N/phosphorus (P)/potassium (K) addition) in a factorial design. We focused on the effects of these treatments on species diversity (species richness, Shannon index, abundance), ANPP, plant functional traits, and soil properties. We used structural equation model (SEM) to evaluate the direct and indirect effects of precipitation amount and nutrient addition on ANPP through affecting species diversity and functional traits. Results: Increasing precipitation increased species diversity and ANPP. NPK addition and increased 50% precipitation significantly increased ANPP over all other treatment combinations. Drought (-50%) reduced plant height and leaf dry matter content (LDMC), but increased leaf nitrogen content (LNC). Species richness, abundance, height and LDMC were positively correlated with ANPP, while specific leaf area (SLA) and LNC were negatively correlated with ANPP. SEM suggested that precipitation amount indirectly affected ANPP through its effect on abundance and SLA, while nutrient addition indirectly affected ANPP only through its effect on abundance. Conclusion: In desert steppe, the interaction of precipitation and nutrient addition had a significant positive effect on ANPP, which was mainly mediated by species diversity and functional traits. Our results highlight the importance of species diversity and functional traits in driving short-term responses of ANPP to environmental factors in desert steppe ecosystems. [ABSTRACT FROM AUTHOR]

Extensive studies have shown that the success of invasive plants in large environmental gradients can be partly attributed to related factors, including phenotypic plasticity and rapid evolution. To enhance their ability to compete and invade, invasive plants often show higher morphological and physiological plasticity to adapt to different habitat conditions. In the past two decades, invasive species have expanded to some new habitats in North and Northwest China, including arid oasis agricultural zones, which are disturbed by human activities, and the ecosystem itself is very fragile. To evaluate the ecological adaptability of invasive plants widely distributed in North and Northwest China, we studied the physiological response and tolerance mechanism of different geographical populations of Solanum rostratum Dunal to different drought-stress gradients in extremely arid regions (Xinjiang population) and semi-arid regions (Inner Mongolia population). The results showed that with the aggravation of drought stress, S. rostratum from different geographical populations adopted different physiological mechanisms to drought stress. Xinjiang population was mostly affected by root/shoot ratio and chlorophyll fluorescence characteristics, showing higher plasticity in the net and total photosynthetic rates, while the Inner Mongolia population mainly relied on the accumulation of osmotic adjustment substances, higher leaf dry matter content, and increased malondialdehyde to cope with drought stress. Based on these results, we concluded that the physiological responses of S. rostratum invading different habitats in northern China to drought stress were significantly different. The drought resistance of the Xinjiang population was higher than that of the Inner Mongolia population. In general, S. rostratum can be widely adapted to both harsh and mild habitats through phenotypic plasticity, threatening agricultural production and ecological environment security in northern China. [ABSTRACT FROM AUTHOR]

There are water resource shortages and frequent drought disasters in the arid region of northwestern China (ARNC). The purpose of this study is to understand the spatiotemporal variations of the droughts in this region and to further estimate future changes. Multiple drought indexes such as the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index (SPEI), and the self-calibrated Palmer drought severity index (SC-PDSI) are used to investigate the temporal and spatial characteristics of the ARNC drought from 1950 to 2012. Our results indicate the following: (1) The drought indexes exhibit significant increasing trends, and the highest drought frequency occurred in the 1960s, followed by a decreasing trend during the next few decades. All four seasons exhibit a wet trend, with a higher drought frequency in summer than in the other seasons. (2) The changes of the drought indexes in the ARNC also exhibit distinct spatial variations, with a wet trend in the subregions of North Xinjiang (NXJ), the Tianshan Mountains (TS), South Xinjiang (SXJ), and the Qilian Mountains (QL), but with a dry trend in the subregions of the Hexi Corridor (HX) and the western part of Inner Mongolia (WIM). (3) There was a major climate variability in the ARNC that occurred in the 1980s, and there were dry and wet climate oscillation periods of 8a, 17a, and >20a. [ABSTRACT FROM AUTHOR]

From the early Qing dynasty (1644–1911) to the beginning of the People's Republic, men in northern China from drought-prone regions of northwestern Shanxi province and northeastern Shaanxi province would travel beyond the Great Wall to find work in western Inner Mongolia, in a migration known as "going beyond the Western Pass" 走西口. This article analyzes anthologized song lyrics and ethnographic interviews about this migration to explore how songs of separation performed at temple fairs approached danger and abandonment using traditional metaphors and "folk models" similar to those of parents protecting children from life's hazards and widows and widowers lamenting the loss of loved ones. I argue that these duets between singers embodying the roles of migrant laborers and the women they left behind provided a public language for audiences to reflect upon and contextualize private emotions in a broader social context, offering rhetorical resolutions to ambivalent anxieties. [ABSTRACT FROM AUTHOR]

Unanticipated environmental shocks impact the livelihoods of many resource users around the world. These shocks are likely to be more unpredictable as the effects of climate change continue to mount. Yet how households adapt to these changing climatic conditions especially in the context of rapidly changing market conditions in most areas of the world, is poorly understood. These interactions have wide implications for both smallholder livelihoods and sustainable use of natural resources. In this paper, we examine the relationship between environmental shocks and stocking rates in livestock herds in the Inner Mongolian grasslands of northern China. We uniquely examine three types of shocks and how households adapt livestock production strategies in response to each. Separately and in aggregate, we look at three common shocks in Inner Mongolia: droughts, snowstorms, and locust outbreaks. We use a difference-in-differences approach to estimate changes in stocking rates among households that experience shocks versus those that do not with a panel dataset from 2009 to 2014 of 597 households. While we find no clear impact from locusts, our results suggest droughts and snowstorms have opposite effects: droughts are associated with increases in herd sizes, but snowstorms result in decreased herds. We suggest these differences are due to interactions between shocks, emerging options to borrow on credit, and livestock markets. Household adaptation to climate change will be strategic and take advantage of both available resources as well as market conditions. • Climate change is causing stronger and more unpredictable environmental shocks. • We use a difference-in-differences model to estimate the impact of shocks on stocking rate. • Drought relates to bigger herds; snowstorms relate to smaller herds. • Households adapt to shocks taking advantage of both available resources and market conditions. • Shaping well-functioning market may reduce opportunistic resource exploitation. [ABSTRACT FROM AUTHOR]

From the early Qing dynasty (1644–1911) to the beginning of the People's Republic, men in northern China from drought-prone regions of northwestern Shanxi province and northeastern Shaanxi province would travel beyond the Great Wall to find work in western Inner Mongolia, in a migration known as "going beyond the Western Pass" 走西口. This article analyzes anthologized song lyrics and ethnographic interviews about this migration to explore how songs of separation performed at temple fairs approached danger and abandonment using traditional metaphors and "folk models" similar to those of parents protecting children from life's hazards and widows and widowers lamenting the loss of loved ones. I argue that these duets between singers embodying the roles of migrant laborers and the women they left behind provided a public language for audiences to reflect upon and contextualize private emotions in a broader social context, offering rhetorical resolutions to ambivalent anxieties. [ABSTRACT FROM AUTHOR]

Drought has a deep impact in Inner Mongolia, which relies on livestock and farming. The temporal and spatial variability of drought conditions in Inner Mongolia were analyzed with a drought severity index (DSI), which is derived from the ratio of evapotranspiration to potential evapotranspiration and the normalized difference vegetation index (NDVI), as measured by remote sensing. Soil moisture as an important drought measure has not been used in the calculation of DSI. Using monthly DSI data during the growing season (May–September) in 2001–2010, the relationship between DSI and soil moisture was investigated with correlation coefficient and regression analysis. Different seasonal and spatial patterns of drought occurrence were found in the notable drought years of 2001, 2007, and 2009. The largest correlations between DSI and soil moisture were attributed to the links between evapotranspiration and soil moisture. The spatial distribution of the correlation coefficients between DSI and soil moisture varied seasonally, tracking closely with the movement of rainfall belt. DSI could not reflect the variation of soil moisture in woodland. In grassland, DSI correlated with surface soil moisture in the east in the beginning of the growing season. As the rainfall belt expands to the west in the second half of the growing season, DSI reflected apparently deeper soil moisture conditions because of the spatial difference of soil properties, i.e., the water-holding capacity becomes larger from west to east. [ABSTRACT FROM AUTHOR]

Differences in key physiological characteristics between plant species can result in their contrasting performances in vegetation restoration projects, but ecophysiological comparative studies in close relation to ecological restoration projects are scarce. Hedysarum fruticosum Pall. and Caragana microphylla Lam. are two leguminous shrub species widely used in combination for fixation of active sand dunes in semiarid regions of northern China, but they clearly differ in fitness at different stages of dune vegetation development; that is, H. fruticosum quickly gains a community dominance at the initial stage but yields to C. microphylla in a few years after the fixation of dunes. To reveal the underlying mechanism of such a pattern, key physiological characteristics related to xylem water transport, leaf water use, and drought tolerance were compared between these two species at a typical site of sand dune fixation project in Inner Mongolia. Compared with C. microphylla, H. fruticosum shows an acquisitive and risky water management strategy with substantially higher hydraulic efficiency and photosynthetic capability but reduced resistance to drought‐induced xylem embolism, which endows it an advantage under conditions of relatively high soil water availability at the early stage of dune fixation. In contrast, C. microphylla exhibits more conservative water use and characteristics of greater drought tolerance, which results in greater dominance under the more drought‐stressed conditions of the later stage of dune fixation. Our study for the first time provides a potential mechanistic explanation for the clear switching of dominant positions between the two important sand‐fixing shrub species during the sand dune revegetation process. [ABSTRACT FROM AUTHOR]

Naturally growing vegetation often suffers from the effects of drought. There exists a vast number of drought indices (DI's) to assess the impact of drought on the growth of crops and naturally occurring vegetation. However, assessing the fitness of these indices for large areas with variable vegetation cover is often problematic because of the absence of adequate spatial information. In this study, we compared six DI's to NDVI (the normalized difference vegetation index), a common indicator of vegetation occurrence and health based on satellite-acquired reflectance data. The study area covers an aridity gradient from forests to deserts along a 2,400-km-long section across the Inner Mongolia Autonomous Region of China. On an annual timescale, standardized precipitation index (SPI) was the most appropriate in assessing drought in steppes and deserts. On a seasonal timescale, the self-calibrated Palmer drought severity index (scPDSI) displayed the greatest sensitivity during the summer, but not during the other seasons. On a monthly timescale, scPDSI demonstrated the greatest sensitivity to the various vegetation zones (i.e., forests, steppes, and deserts) in June and July. Further analysis indicated that summer drought had a lag-effect on vegetation growth, which varied from one to six months according to the specific vegetation cover. The mixed response of DI's to NDVI and the lag-effect in transitional vegetation on annual, seasonal, and monthly timescales were ascribed to differences in DI definition and the dominant plant species within the transitional cover. The current study has the potential to inform the drafting of selection criteria of DI's for the study of drought-related impact on naturally growing vegetation at timescales from month to year. [ABSTRACT FROM AUTHOR]

Natural disaster vulnerability can intuitively reflect the susceptibility of an area to environmental changes. Better understanding the spatial distribution of natural disaster vulnerability is a critical process for taking effective adaptation and management. Although significant achievements have been made in disaster vulnerability, few studies are known about natural disaster vulnerability at the national scale, especially from the typical natural disaster events in China. In this study, with normalizing selected indicators and calculating vulnerability index, we analyzed the spatial distribution of natural disasters vulnerability during 2010–2017 using the geospatial techniques. The results showed that natural disaster vulnerability has certain spatial differences, but different natural disaster can occur in the same area during the study period. Drought disaster can occur in all regions of China, especially in Inner Mongolia. Flood disaster is mainly concentrated in the middle and lower reaches of the Yangtze River and the Yellow River Basin. The wind and storm disaster is chiefly in the northern regions in China. The freezing disaster is widely distributed in China. Furthermore, the regions with low vulnerability were primarily distributed in the eastern coastal region, indicating that the rapid development of economy and technology can resist or mitigate natural disaster to a certain extent. This study offers a solution to study natural disasters and provides scientific basis for disaster prevention and mitigation actions. [ABSTRACT FROM AUTHOR]

Aims: Long-duration drought can alter ecosystem plant species composition with subsequent effects on carbon cycling. We conducted a rainfall manipulation field experiment to address the question: how does drought-induced vegetation change, specifically shrub encroachment into grasslands, regulate impacts of subsequent drought on soil CO2 efflux (Rs) and its components (autotrophic and heterotrophic, Ra and Rh)? Methods: We conducted a two-year experiment in Inner Mongolia plateau, China, using constructed steppe communities including graminoids, shrubs and their mixture (graminoid + shrub) to test the effects of extreme-duration drought (60-yr return time) on Rs, Rh and Ra. Results: Our results indicated that extreme-duration drought reduced net primary production, with subsequent effects on Rs, Rh and Ra in all three vegetation communities. There was a larger relative decline in Ra (35–54%) than Rs (30–37%) and Rh (28–35%). Interestingly, we found Rs in graminoids is higher than in shrubs under extreme drought. Meanwhile, Rh declines were largest in the shrub community. Although Ra and Rh both decreased rapidly during drought treatment, Rh recovered quickly after the drought, while Ra did not, limiting the Rs recovery. Conclusions: This study suggests that plant species composition regulates several aspects of soil CO2 efflux response to climate extremes. This regulation may be limited by above- and below-ground net primary production depending on soil water availability. The results of this experiment address a critical knowledge gap in the relationship between soil respiration and plant species composition. With shrub encroachment into grasslands, total soil respiration is reduced and can partly offset the effect of reduction in productivity under drought stress. [ABSTRACT FROM AUTHOR]

Understanding the effects of climate change, in particular, climate extremes on plant functional traits can provide a mechanistic basis for predicting how plant communities may be altered in the future. Here, we focused on a dominant species in Inner-Mongolia typical temperate steppe, Leymus chinensis (Trin.) Tzvei, to examine the responses of plant functional traits to experimentally imposed extreme drought at three sites along an aridity gradient. When comparing the driest (high aridity) to the wettest sites (low aridity), plant height, leaf dry matter content and δ13C (water use efficiency) were increased at the intermediate and low aridity sites, whereas specific leaf area and leaf nitrogen content were reduced at the high-aridity site. When extreme drought (~ 66% reduction in the growing season precipitation) was experimentally imposed at all sites, plant height decreased and δ13C of L. chinensis increased at the intermediate and low aridity sites. The extreme drought of 66% precipitation reduction also increased leaf dry matter content in high- and low-aridity sites. Compared to the control (ambient precipitation), extreme drought increased the strength of the positive association between plant height and δ13C, as well as the negative associations of specific leaf area with plant height and leaf dry matter content. Thus, extreme drought altered key functional traits of the dominant grass of Inner Mongolia steppe, particularly at the low-aridity site where the drought decreased plant size and increased water use efficiency and affected relationships between these traits. [ABSTRACT FROM AUTHOR]

The standardized precipitation evapotranspiration index (SPEI) was widely used in climatology and hydrology studies, because its combination the sensitivity of the PDSI to the changes in ET (caused by air temperature fluctuations and trends) with the simplicity of calculation, but also has the robustness of the multitemporal nature of the SPI. In this article, the temporal and spatial pattern of drought based on SPEI was explored in the Inner Mongolia during 1960-2013. The results showed that SPEI can effectively reveal the multiscalar feature of drought, and the effect of air temperature rising on drought severity and cumulative effect of drought itself. SPEI is suitable for those longer time scales such as 6-month or longer, and better in semi-humid and semi-arid areas than in arid area, due to much zero values or extreme maximum values at shorter time scale or in arid area. Generally, there is a drying trend in the whole Inner Mongolia, and a very severe drought was revealed at multi-time scales during the 2000s. Annual SPEI change at 6-month scale from APR to SEP indicated that drought in plant-growth season is very frequent and increasingly serious, and it should be given more attention. The severities of drought vary in different sub-regions. A significant abrupt change point of drought change trend in the whole Inner Mongolia at 12-month time scale was diagnosed in late 1990s, while this abrupt point in the middle-west subarea is a little earlier than those in the northeast subarea and the southeast subarea. This lasting severe drought should be the result of joint action of increasing air temperature and obviously decreasing precipitation since 2000s. At the same time, the most severe and frequent drought mainly occurred along the Sino-Mongolia border and the Horqin Sandy Land, while the continuous belt along the Da Hinggan Ling Mountains, the Yinshan Mountains, the Hetao Plain and the Mu Us Sandy Land is the area with relative slight drying trend during the last decades. Drought spatial pattern indicated by SPEI was supported by spatial distribution of temperature vegetation drought index based on remote sensing. [ABSTRACT FROM AUTHOR]

Few studies have investigated the influence of water availability on plant population spatial patterns. We studied changes in the spatial patterns of Caragana stenophylla along a climatic drought gradient within the Inner Mongolian Plateau, China. We examined spatial patterns, seed density, “nurse effects” of shrubs on seedlings, transpiration rates and water use efficiency (WUE) of C. stenophylla across semi-arid, arid, and intensively arid zones. Our results showed that patches of C. stenophylla populations shifted from a random to a clumped spatial pattern towards drier environments. Seed density and seedling survival rate of C. stenophylla decreased from the semi-arid zone to the intensively arid zone. Across the three zones, there were more C. stenophylla seeds and seedlings underneath shrub canopies than outside shrub canopies; and in the intensively arid zone, there were almost no seeds or seedlings outside shrub canopies. Transpiration rates of outer-canopy leaves and WUE of both outer-canopy and inner-canopy leaves increased from the semi-arid zone to the intensively arid zone. In the intensively arid zone, transpiration rates and WUE of inner-canopy leaves were significantly lower and higher, respectively, than those of outer-canopy leaves. We conclude that, as drought stress increased, seed density decreased, seed proportions inside shrubs increased, and “nurse effects” of shrubs on seedlings became more important. These factors, combined with water-saving characteristics associated with clumped spatial patterns, are likely driving the changes in C. stenophylla spatial patterns. [ABSTRACT FROM AUTHOR]

This study applied grassland related multi-index and assessed the effects of climate change by investigating grassland responses to drought. This process was performed to study grassland vegetation dynamic accurately and evaluate the effect of drought in the Mongolian Plateau (MP). The spatial–temporal characteristics of grassland dynamic in terms of coverage (Fv), surface bareness (Fb), and net primary production (NPP) from 2000 to 2013 were explored. We implemented the maximum Pearson correlation to analyze the grassland vegetation in response to drought by using self-calibrating Palmer Drought Severity Index (scPDSI). Results show that Fv and NPP present an increasing trend (0.18 vs. 0.43). Fb showed a decreasing trend with a value of −0.16. The grassland Fv and NPP positively correlated with scPDSI, with a value of 0.12 and 0.85, respectively, and Fb was −0.08. The positive correlation between Fv and NPP accounted for 84.08%, and the positive correlation between Fv and scPDSI accounted for 93.88%. On the contrary, the area with a negative correlation between Fb and scPDSI was 57.43%. The grassland in the MP showed a recovery tendency. The increase in grassland caused by positive reaction was mainly distributed in the middle of Mongolia (MG), whereas that caused by counter response was mainly distributed in the east and west MG and northeast Inner Mongolia autonomous region of China (IM). The relevant results may provide useful information for policymakers about mitigation strategies against the inverse effects of drought on grassland and help to ease the losses caused by drought. [ABSTRACT FROM AUTHOR]

Arid grassland ecosystems have significant interannual variation in carbon exchange; however, it is unclear how environmental factors influence carbon exchange in different hydrological years. In this study, the eddy covariance technique was used to investigate the seasonal and interannual variability of CO2 flux over a temperate desert steppe in Inner Mongolia, China from 2008 to 2010. The amounts and times of precipitation varied significantly throughout the study period. The precipitation in 2009 (186.4 mm) was close to the long-term average (183.9±47.6 mm), while the precipitation in 2008 (136.3 mm) and 2010 (141.3 mm) was approximately a quarter below the long-term average. The temperate desert steppe showed carbon neutrality for atmospheric CO2 throughout the study period, with a net ecosystem carbon dioxide exchange (NEE) of −7.2, −22.9, and 26.0 g C m−2 yr−1 in 2008, 2009, and 2010, not significantly different from zero. The ecosystem gained more carbon in 2009 compared to other two relatively dry years, while there was significant difference in carbon uptake between 2008 and 2010, although both years recorded similar annual precipitation. The results suggest that summer precipitation is a key factor determining annual NEE. The apparent quantum yield and saturation value of NEE (NEEsat) and the temperature sensitivity coefficient of ecosystem respiration (Reco) exhibited significant variations. The values of NEEsat were −2.6, −2.9, and −1.4 µmol CO2 m−2 s−1 in 2008, 2009, and 2010, respectively. Drought suppressed both the gross primary production (GPP) and Reco, and the drought sensitivity of GPP was greater than that of Reco. The soil water content sensitivity of GPP was high during the dry year of 2008 with limited soil moisture availability. Our results suggest the carbon balance of this temperate desert steppe was not only sensitive to total annual precipitation, but also to its seasonal distribution. [ABSTRACT FROM AUTHOR]

Vegetation net primary productivity (NPP) is an important aspect of the global carbon cycle, and its change is closely related to climate change. This study analyzed the spatial-temporal variation of the standardized precipitation evapotranspiration index (SPEI) and NPP in the Mongolian Plateau, and investigated the effect of drought on NPP. To this end, NPP was simulated using the Carnegie-Ames-Stanford Approach (CASA) model. The results showed that from 1982 to 2014, NPP exhibited an upward trend in different seasons, and a significant increasing trend in most areas in the growing season and spring. The degree of drought also showed an increasing trend in each season. Moreover, the decrease in NPP and SPEI in Mongolia was larger than that in Inner Mongolia. Vegetation showed a positive correlation with SPEI in the growing season and summer, but a negative correlation in the other seasons. Moreover, the impact of drought on vegetation in the growing season showed a lag effect, whereas the lag response was inconspicuous during the early stages of the growing season. Different vegetation NPP responded strongly to the SPEI of the current month and the previous month. [ABSTRACT FROM AUTHOR]

Understanding the variations of future drought under climate warming can provide the basis for mitigation efforts. This study utilized the standardized precipitation evapotranspiration index (SPEI), empirical mode decomposition (EMD) and empirical orthogonal function analysis (EOF) to predict the spatiotemporal variation of future drought under the representative concentration pathway RCP4.5 and RCP8.5 scenarios within the Mongolian Plateau over the period 2020–2100. The SPEI was computed using temperature and precipitation data generated by the fifth stage of the Coupled Model Intercomparison Project (CMIP5). The results under both the RCP4.5 and RCP8.5 scenarios showed increasing changes in temperature and precipitation. Both scenarios indicated increases in drought, with those under RCP8.5 much more extreme than that under RCP4.5. Under both scenarios, the climate showed an abrupt change to become drier, with the change occurring in 2041 and 2054 for the RCP4.5 and RCP8.5 scenarios, respectively. The results also indicated future drought to be more extreme in Mongolia than in Inner Mongolia. The simulated drought pattern showed an east–west antiphase and a north–south antiphase distribution based on EOF. The frequency of drought was higher under RCP8.5 compared to that under RCP4.5, with the highest frequencies under both scenarios occurring by the end of the 21st century, followed by the mid-21st century and early 21st century. The findings of this research can provide a solid foundation for the prevention, early warning and mitigation of drought disasters within the context of climate change in the Mongolian Plateau. [ABSTRACT FROM AUTHOR]

The global climate is noticeably warming, and drought occurs frequently. Therefore, choosing a suitable index for drought monitoring is particularly important. The standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) are commonly used indicators in drought monitoring. The SPEI takes temperature into account, but the SPI does not. In the context of global warming, what are their differences and applicability in regional drought monitoring? In this study, after calculating the SPI and SPEI at 1-, 3-, 6-, and 12-month timescales at 102 meteorological stations in Inner Mongolia from 1981 to 2018, we compared and analyzed the performances of the SPI and SPEI in drought monitoring from temporal and spatial variations, and the consistency and applicability of the SPI and SPEI were also discussed. The results showed that (1) with increasing timescale, the temporal variations in the SPI and SPEI were increasingly consistent, but there were still slight differences in the fluctuation value and continuity; (2) due to the difference in time series, the drought characteristics identified by the SPI and SPEI were quite different in space at various timescales, and with the increase in timescale, the spatial distributions of the drought trends in Inner Mongolia were basically consistent, except in Alxa; (3) at the shortest timescale, the difference between the SPI and SPEI was the largest, and the drought reflected by the SPI and SPEI may be consistent at long timescales; and (4) compared with typical drought events and vegetation indexes, the SPEI may be more suitable than the SPI for drought monitoring in Inner Mongolia. It should be noted that the adaptability of the SPI and SPEI may be different in different periods and regions, which remains to be analyzed in the future. [ABSTRACT FROM AUTHOR]