Ecotone Of Inner Mongolia Research Articles

Innovative Perspectives on Ecological Assessment in the Agro-Pastoral Ecotone of Inner Mongolia: An Integrated Evaluation and Forecast of Landscape and Ecological Risks and Drivers

The agro-pastoral ecotone of Inner Mongolia, one of China’s most ecologically vulnerable regions, requires careful evaluation and prediction of landscape ecological risks to improve its environment and support sustainable development. Our study built a model to assess the landscape ecological risks from 1990 to 2020 using land use data from Google Earth Engine. We examined the changes in landscape ecological risks and their driving factors through spatial autocorrelation analysis and geographic detectors. Future ecological risks from 2025 to 2040 were predicted using the multi-criteria evaluation-cellular automata-Markov model. Results revealed a declining trend in both disturbance and loss intensity across land use types, with the overall ecological risk index also decreasing. Higher risk areas were concentrated in the east and southwest, while lower risks were observed in the north and center. Temperature and precipitation are key natural factors, while the impact of Gross Domestic Product (GDP), a human factor, on ecological risk is increasing and surpassed natural influences in 2015 and 2020. In the future, the highest risk areas will remain in the southwest and northeast. This study provides detailed evidence and guidance for ecological safety and sustainable development in the agro-pastoral ecotone of Inner Mongolia.

Exploring the Water-Soil-Crop Dynamic Process and Water Use Efficiency of Typical Irrigation Units in the Agro-Pastoral Ecotone of Northern China.

Groundwater resources serve as the primary source of water in the agro-pastoral ecotone of northern China, where scarcity of water resources constrains the development of agriculture and animal husbandry. As a typical rainfed agricultural area, the agro-pastoral ecotone in Inner Mongolia is entirely dependent on groundwater for agricultural irrigation. Due to the substantial groundwater consumption of irrigated farmland, groundwater levels have been progressively declining. To obtain a sustainable irrigation pattern that significantly conserves water, this study faces the challenge of unclear water transport relationships among water, soil, and crops, undefined water cycle mechanism in typical irrigation units, and water use efficiency, which was not assessed. Therefore, this paper, based on in situ experimental observations and daily meteorological data in 2022-2023, utilized the DSSAT model to explore the growth processes of potato, oat, alfalfa, and sunflower, the soil water dynamics, the water balance, and water use efficiency, analyzed over a typical irrigation area. The results indicated that the simulation accuracy of the DSSAT model was ARE < 10%, nRMSE/% < 10%, and R2 ≥ 0.85. The consumption of the soil moisture during the rapid growth stage for the potatoes, oats, alfalfa, and sunflower was 7-13% more than that during the other periods, and the yield was 67,170, 3345, 6529, and 4020 kg/ha, respectively. The soil evaporation of oat, potato, alfalfa, and sunflower accounted for 18-22%, 78-82%; 57-68%, and 32-43%, and transpiration accounted for 40-44%, 56-60%, 45-47%, and 53-55% of ETa (333.8 mm-369.2 mm, 375.2 mm-414.2 mm, 415.7 mm-453.7 mm, and 355.0 mm-385.6 mm), respectively. It was advised that irrigation water could be appropriately reduced to decrease ineffective water consumption. The water use efficiency and irrigation water use efficiency for potatoes was at the maximum amount, ranging from 16.22 to 16.62 kg/m3 and 8.61 to 10.81 kg/m3, respectively, followed by alfalfa, sunflowers, and oats. For the perspective of water productivity, it was recommended that potatoes could be extensively cultivated, alfalfa planted appropriately, and oats and sunflowers planted less. The findings of this study provided a theoretical basis for efficient water resource use in the agro-pastoral ecotone of Northern China.

Spatial Distribution Characteristics of Soil C:N:P:K Eco-Stoichiometry of Farmland and Grassland in the Agro-Pastoral Ecotone in Inner Mongolia, China

Ecological stoichiometry (ES) is an important index that reflects the balance of various elements in ecological processes. Therefore, it is of great significance to understand the soil nutrient cycle to clarify the environmental control of soil carbon (C), nitrogen (N), phosphorus (P), and potassium (K). In this study, we analyzed the spatial distribution of soil C, N, P, and K contents and the C:N:P:K stoichiometric characteristics of 0–20 cm and 20–40 cm of farmland and grassland in four agro-pastoral areas in Inner Mongolia. Spearman correlation was used to analyze the effects of environmental factors on the soil C:N:P:K stoichiometric relationship. The results showed that there was no fixed Redfield ratio for the soil stoichiometric relationship of farmland and grassland in Inner Mongolia, and the values were 15:2:1:9 to 145:10:1:26 and 25:1:1:29 to 228:15:1:65, respectively. The stoichiometric relationships between farmland and grassland were consistent with the law of geographical and spatial heterogeneity. The ratios of C:N, C:P, C:K, N:P, and N:K showed an N distribution from west to east, while the ratio of P:K showed a V distribution. The stoichiometric relationships in grassland soil were mainly affected by soil organic carbon and total nitrogen content, while those in farmland were mainly affected by total nitrogen and total phosphorus content. The annual mean precipitation has a significant effect on stoichiometric relationships in farmland, while the annual mean temperature has a more significant effect on grassland. In conclusion, the spatial distribution difference in the soil stoichiometric relationship in the agro-pastoral ecotone of Inner Mongolia was more significant than the difference in the land use pattern. The influences of annual mean temperature and annual mean precipitation on soil ecological stoichiometry were in accordance with the geographical spatial similarity law. Compared with grassland, the stoichiometric relationship of farmland soil was greatly affected by fertilization, and farmland in this region was mainly limited by carbon and nitrogen. Thus, field management should be carried out according to local conditions. This study is of great significance as it promotes the rational utilization of land resources and the sustainable development of agriculture.

The Impact of Anthropogenic Activities and Natural Factors on the Grassland over the Agro-Pastoral Ecotone of Inner Mongolia

The agro-pastoral ecotone serves as an important ecological transition zone between grassland and cropland. It plays a crucial role in providing forage and maintaining the ecological security of Northern China. China has initiated many ecological restoration projects in the agro-pastoral ecotone. Separating the affecting factors of anthropogenic activities and natural factors change on grassland may help guide future ecological restoration projects. This study investigated the grassland change over the agro-pastoral ecotone in Inner Mongolia (APEI) using land use data, vegetation index, and monthly climate data, social and economic data from 2010 to 2020. Two indicators were introduced to evaluate the grassland change in quality and quantity. The average annual maximum NDVI of grassland within each sample was used as a proxy for grassland quality, and the proportion of grassland within each sample was used as a proxy for grassland quantity. The driving mechanisms of grassland quality were examined on different types of grassland. The results showed that (1) from 2010 to 2020, the quantity of grassland in APEI slightly decreased while the quality of the grassland significantly improved; (2) the change in grassland quality was jointly caused by natural factors and human activities, with 66.77% being attributed to natural factors and 33.23% to human activities. In some areas, the alteration in grassland quality was solely determined by either the impacts of natural factors or human-induced disturbances; and (3) temperature and precipitation played different roles in affecting grassland quality among different types of grassland. In some areas, anthropogenic activities, such as farmland and population, would affect grassland quality. The findings of this study would contribute to the understanding of the mechanism of ecological environmental changes in the agro-pastoral ecotone and guide the planning and implementation of future ecological restoration projects in agro-pastoral areas.

Edge grassland provide a stronger thermal buffer against core grassland in the agro-pastoral ecotone of Inner Mongolia

The impact of land use/cover change on land surface temperature is an important topic in research on biodiversity, environment planning, sustainability. However, such studies are rare in grassland ecosystems. Based on morphological spatial pattern analysis, we analyzed the change in grassland landscape patterns in the agro-pastoral ecotone of Inner Mongolia from 2000 to 2020. We also examined the impact of grassland landscape pattern change on productivity and land surface temperature. We found that the grassland area decreased significantly, with grassland fragmentation increasing during the past 20 years. A series of landscape types showed different area changes: the area of islet and perforation increased, and the area of core, edge, and bridge decreased. Compared with the core grassland, the edge grassland shows higher productivity, which is a positive edge effect. Moreover, the edge grassland has a lower daytime temperature, higher nighttime temperature, and a smaller daily range than that in the core grassland. Our study highlights that the edge grassland has higher productivity and stronger thermal buffering. We suggest that more attention should be paid to the edge areas in grassland management to alleviate the thermal stress caused by human induced climate change.

Promotion and sustainable development of beef cattle farming industry in agro-pasture ecotone areas, Inner Mongolia of China: A comparison between two fattening systems

The agro-pasture ecotone is distributed all around the world. In these areas, the productive land forces are decreasing, and due to the irrational economic activities and the vulnerable ecological environment in these regions occurs land degradation. This study focuses on the effect of two different fattening approaches of beef cattle and output from the economic point of view by using a cost-benefit analysis technique in the eastern agro-pasture ecotone of Inner Mongolia, China. This study considers the environmental, social, and economic costs as input factors and concludes that both fattening systems have different characteristics. The result shows that the intensive farming system has more fluctuation and instability in terms of the number of animals due to the feed shortage in the local area. In comparison, the continuous fattening system is much more efficient and sustainable in terms of cost management and benefit analysis due to the local condition of the area. The empirical results indicate that the beef cattle industry has a high marginal return. Our research highlights the need to prioritize local resources and incorporate feed-intensity analysis in livestock.

Influence of Different Proportion Intercropping on Oat and Common Vetch Yields and Nutritional Composition at Different Growth Stages

Crop yield mainly depends on environment and cultivation practices that vary according to a growing environment. However, an oat (Avena sativa L.)-common vetch (Vicia sativa L.) intercrop system has not been fully developed in the agro-pastoral ecotone of Inner Mongolia, China. This study evaluated the effects of seven treatments, including five oat-common vetch intercropping patterns, sole oat, and sole vetch on yield and quality performance at different growth periods [75 days after sowing (DAS), 90 DAS, 105 DAS], on the basis of field experiments conducted in the agro-pastoral ecotone of Inner Mongolia in 2015 and 2016. The OV3:1 (oat intercropped with common vetch at seeding ratios 3:1) treatment at 105 DAS in 2016 was superior to other treatments, as it achieved the highest shoot dry matter, increasing by 24.1% and 37.1% compared to sole oat and common vetch. The crude fat (CF) contents, CF yield, and crude protein (CP) yield increased under OV3:1, and acid detergent fiber (ADF) decreased under OV3:1, compared to monoculture. The results indicate that intercropping is an efficient cropping system for the agro-pastoral ecotone of Inner Mongolia. The appropriate proportion of oat and common vetch intercropping at 3:1 and harvesting time not only increases crop yield but also improves the crop quality.

Spatial distribution and influencing factors of settlements in the farming–pastoral ecotone of Inner Mongolia, China

ABSTRACT Rural settlements serve as an important part of the rural landscape, and environmental conditions influence their spatial distribution. We hypothesize that there are variations in the spatial patterns of settlements across different farming–pastoral ecotones that exist in accordance with different human activities and environmental conditions. We used remote sensing imagery, digital elevation model, and GIS technology to analyze and compare the spatial patterns of settlements and factors influencing these patterns across pastoral, agricultural, and ecotone areas in Inner Mongolia, China. A Voronoi model, adjacency analysis, landscape metrics, and quantitative analysis were conducted. The results indicated that (1) the settlements in the three areas tended to have a random spatial distribution, and although there were no significant differences between the settlement types, agricultural settlements tended to be clustered and pastoral settlements tended to be evenly distributed; (2) the pastoral area had only a few large and sparsely fragmented patches; (3) the factors influencing settlement distribution mainly differed with respect to the NDVI, distance to roads and rivers, and elevation across three areas, but the slope degree was similar. These results indicated there are no significant differences between the spatial patterns of settlements along the agricultural to pastoral gradient, although environmental conditions differ. Consequently, we can optimize the spatial pattern of settlements and achieve sustainable development within farming–pastoral ecotones.

Intensive land-use drives regional-scale homogenization of plant communities

Intensive anthropogenic land-use causes habitat loss and landscape homogenization, which leads to the decrease of biodiversity and ecosystem degradation. Therefore, it is important to study the influence of landscape heterogeneity on biodiversity. In this study, vegetation surveys conducted at 53 sites in the Tabu River basin, located at the agro-pastoral ecotone of Inner Mongolia of China, revealed 146 species. Species diversity was evaluated at three scales: species richness within patches (alpha diversity), between patches (beta diversity) and at the landscape scale (gamma diversity). We analyzed landscape heterogeneity (LHtotal) and its driving factors including environmental variables (LHDFenv-var, such as precipitation and altitude), environmental heterogeneity (LHDFenv-het) and human activities (LHDFhum). We used structural equation modeling (SEM) to evaluate the response of species richness to landscape heterogeneity at three scales and determined the relative contribution of driving factors in explaining species diversity at these scales. The results of the study are summarized as follows: 1) Alpha diversity was the dominant component of gamma diversity in the Tabu River basin in Inner Mongolia. 2) There is no significant correlation (P = 0.512) between alpha diversity and LHtotal; with the increase of LHtotal beta and gamma diversities showed hump-shaped relationships. 3) LHDFenv-het was the primary factor in maintaining alpha diversity, with heterogeneity of mean annual precipitation (MAP), temperature (MAT) and altitude (ALT) acting as three largest contributors. LHDFhum primarily contributed to the maintenance of beta diversity. 4) LHDFhum was the primary contributor to gamma diversity, and human activity exceeded threshold values for positive effects. Based on our findings we suggest liming agricultural use along the river to prevent reductions in species diversity.

Limiting similarity mediates plant community niche hypervolume across a desert-steppe ecotone of Inner Mongolia

Quantifying niche space occupation based on assessments of multiple resource utilization traits can improve an understanding of plant species coexistence within communities of varying resource availability. We used an ‘occupied functional niche space (OFS)’ method based on multiple leaf traits to examine how plant communities accommodate changes in water availability within a desert-steppe ecotone spanning a limited geographic region. Our study area (western Inner Mongolia) spanned a range of conditions from highly water-limited (desert, D) to less water-limited (desert steppe, S), with two areas capturing the ecotonal boundary between these two vegetation types – partial desert (pD) and partial desert steppe (pS). We tested whether environmental filtering, heterogeneity, or limiting similarity drove trait convergence versus divergence of OFS across a desert-steppe ecotone. We quantified changes in plant community weighted means of both functional (specific leaf area and leaf dry matter content) and stoichiometric (leaf nitrogen content and leaf carbon concentration) leaf traits. OFS in the ecotonal areas (pS and pD) had larger volumes than the most mesic (S) subregion. However, divergence in the centroid of OFS was apparent for the driest (D) subregion, relative to the other three sub-regions. Underlying changes to OFS were changes in plant functional types, with more functional groups found in D and the fewest in S. For community-weighted leaf traits, SLA was highest in the ecotone area (pD and pS), while lowest in D. Further, community weighted means based on leaf dry matter content in D was the highest of all sub-regions, while both community weighted means based on leaf nitrogen content and community weighted means based on leaf dry matter content decreased as precipitation decreased, consistent with expectations. Our results suggest that communities alter both the volume and the centroid of functional trait space to adjust to decreasing water resource availability. We posit that limiting similarity (i.e. competitive exclusion) in water-resource use traits among species, supported by changes in life histories, led to OFS divergence in the ecotonal areas (pS and pD) and D, while environmental filtering may have led to convergence of OFS within the most mesic region (S) as water-stress lessons. In total, our results contribute knowledge as to how plant communities alter trait space in resource acquisition across climatic gradients, and underscores the utility of multi-trait approaches in understanding patterns of species coexistence in response to climatic changes.

Wake up “boiling frogs”: a study on animal husbandry under climate change in Northern China

The development of animal husbandry in China is facing enormous pressure from increasing demand of meat consumption, climate change, degrading grassland, and changing national policies. This paper presents the latest findings from an anthropological field investigation interviewing local herders, traders, and local officials from farming–pastoral ecotone in Inner Mongolia and shed lights on how locals have adapted their lives to climate change and the new national husbandry policies of the twenty-first century. Based on the anthropological interviews, we discussed the future opportunities and challenges of animal husbandry development in farming–pastoral ecotone. Results suggested that national ecological conservation policies and meat price have much larger impacts on animal husbandry than climate change, as perceived by locals. Family Fencing Policy, a relatively new policy aiming to avoid overgrazing and restore vegetation, was neither well accepted nor well implemented by the local herders. This is partially explained by the poor fencing technology, insufficient support facilities, as well as the high costs and low-profit margins in the animal husbandry. We conclude by suggesting that pastoralism in Northern China may greatly benefit from the development of rural cooperatives and active participation of locals in policy designing and implementation.

ANALYSIS ON TEMPORAL-SPATIAL CHANGES OF VEGETATION CVERRGE IN FARMING-PASTORAL ECOTONE OF INNER MONGOLIA

Abstract. Chen Barag Banner is located in the typical farming-pastoral ecotone of Inner Mongolia, and it is also the core area of Hulunbuir steppe. Typical agricultural and pastoral staggered production mode so that the vegetation growth of the region not only determines the local ecological environment, and animal husbandry production, but also have a significant impact on the whole Hulunbuir ecological security and economic development. Therefore, it is necessary to monitor the change of vegetation in this area. Based on 17 MODIS Normalized Difference Vegetation Index (NDVI) images, the authors reconstructed the dynamic change characteristics of Fraction vegetation coverage（FVC）in Chen Barag Banner from 2000 to 2016. In this paper, first at all, Pixel Decomposition Models was introduced to inversion FVC, and the time series of vegetation coverage was reconstructed. Then we analyzed the temporal-spatial changes of FVC by employing transition matrix. Finally, through image analyzing and processing, the results showed that the vegetation coverage in the study area was influenced by effectors including climate, topography and human actives. In the past 17 years, the overall effect of vegetation coverage showed a downward trend of fluctuation. The average vegetation coverage decreased from 58.81 % in 2000 to 48.14 % in 2016, and the area of vegetation cover degradation accounts for 40.09 % of the total change area. Therefore, the overall degradation trend was obvious.

Analyzing vegetation dynamic trend on the Mongolian Plateau based on the Hurst exponent and influencing factors from 1982–2013

This study analyzed the spatial and temporal variations in the Normalized Difference Vegetation Index (NDVI) on the Mongolian Plateau from 1982–2013 using Global Inventory Modeling and Mapping Studies (GIMMS) NDVI3g data and explored the effects of climate factors and human activities on vegetation. The results indicate that NDVI has slight upward trend in the Mongolian Plateau over the last 32 years. The area in which NDVI increased was much larger than that in which it decreased. Increased NDVI was primarily distributed in the southern part of the plateau, especially in the agro-pastoral ecotone of Inner Mongolia. Improvement in the vegetative cover is predicted for a larger area compared to that in which degradation is predicted based on Hurst exponent analysis. The NDVI-indicated vegetation growth in the Mongolian Plateau is a combined result of climate variations and human activities. Specifically, the precipitation has been the dominant factor and the recent human effort in protecting the ecological environments has left readily detectable imprints in the NDVI data series.

Responses of soil respiration to soil management changes in an agropastoral ecotone in Inner Mongolia, China.

Studying the responses of soil respiration (R s) to soil management changes is critical for enhancing our understanding of the global carbon cycle and has practical implications for grassland management. Therefore, the objectives of this study were (1) quantify daily and seasonal patterns of R s, (2) evaluate the influence of abiotic factors on R s, and (3) detect the effects of soil management changes on R s. We hypothesized that (1) most of daily and seasonal variation in R s could be explained by soil temperature (T s) and soil water content (S w), (2) soil management changes could significantly affect R s, and (3) soil management changes affected R s via the significant change in abiotic and biotic factors. In situ R s values were monitored in an agropastoral ecotone in Inner Mongolia, China, during the growing seasons in 2009 (August to October) and 2010 (May to October). The soil management changes sequences included free grazing grassland (FG), cropland (CL), grazing enclosure grassland (GE), and abandoned cultivated grassland (AC). During the growing season in 2010, cumulative R s for FG, CL, GE, and AC averaged 265.97, 344.74, 236.70, and 226.42 gC m−2 year−1, respectively. The T s and S w significantly influenced R s and explained 66%–86% of the variability in daily R s. Monthly mean temperature and precipitation explained 78%–96% of the variability in monthly R s. The results clearly showed that R s was increased by 29% with the conversion of FG to CL and decreased by 35% and 11% with the conversion of CL to AC and FG to GE. The factors impacting the change in R s under different soil management changes sequences varied. Our results confirm the tested hypotheses. The increase in Q 10 and litter biomass induced by conversion of FG to GE could lead to increased R s if the climate warming. We suggest that after proper natural restoration period, grasslands should be utilized properly to decrease R s.

Impact of land use conversion on soil organic carbon stocks in an agro-pastoral ecotone of Inner Mongolia

Soil organic carbon (SOC) stocks in terrestrial ecosystems vary considerably with land use types. Grassland, forest, and cropland coexist in the agro-pastoral ecotone of Inner Mongolia, China. Using SOC data compiled from literature and field investigations, this study compared SOC stocks and their vertical distributions among three types of ecosystems. The results indicate that grassland had the largest SOC stock, which was 1.5- and 1.8-folds more than stocks in forest and cropland, respectively. Relative to the stock in 0–100 cm depth, grassland held more than 40% of its SOC stock in the upper 20 cm soil layer; forest and cropland both held over 30% of their respective SOC stocks in the upper 20 cm soil layer. SOC stocks in grazed grasslands were remarkably promoted after ≥20 years of grazing exclusion. Conservational cultivation substantially increased the SOC stocks in cropland, especially in the 0–40 cm depth. Stand ages, tree species, and forest types did not have obvious impacts on forest SOC stocks in the study area likely due to the younger stand ages. Our study implies that soil carbon loss should be taken into account during the implementation of ecological projects, such as reclamation and afforestation, in the arid and semi-arid regions of China.

Identification of the main factors determining landscape metrics in semi-arid agro-pastoral ecotone

Landscape patterns in agro-pastoral ecotones are influenced by natural factors and human activities. However, the main factors that influence landscape metrics of agro-pastoral ecotones have not been fully elucidated. To further understand conditions influencing landscape formation, we conducted a series analysis to explore the relationship between ecological factors (annual average precipitation, annual average temperature, NDVI, altitude, aspect, slope, curvature, land use, and human disturbance) and landscape metrics pattern in the range of 100–5000 m spatial extent, within an agro-pastoral ecotone in Inner Mongolia, China. Using principal component analysis and the detrended canonical correspondence analysis from 43 landscape metrics, we successfully identified several key factors that determine the landscape metrics values. Agriculture and livestock grazing land use induce the landscape configuration to become homogeneous and simple. Nevertheless, our results show that the influences of human activities on landscape metrics are surprisingly not strong. Rather the natural ecological factors, in particular temperature, precipitation and altitude, had the greatest influence on landscape metrics values. This study provides a theoretical case for the scaling effects and develops techniques for identifying the key ecological factors influencing on landscape metrics, so as to improve landscape management decisions in semi-arid regions and other ecotones.

Cropland age from grassland conversion to cropland affects nitrous oxide emissions

The effects of soil properties and cropland age on atmospheric nitrous oxide (N2O) emissions following the conversion of grassland to cropland in temperate grassland ecosystems are uncertain. In this study, N2O emissions were compared among grassland and cropland soils in the agro-pastoral ecotone of Inner Mongolia over three growing seasons. Four adjacent sites with different land-use histories were selected, including grassland and croplands cultivated for 5, 10, and 50 years after conversion. N2O flux measurements were obtained using a closed-chamber method and were performed continuously during vegetation periods. After the conversion of grassland to cropland, N2O emission initially decreased and thereafter increased in the study sites. The cumulative N2O emissions of the cropland soils 5 and 10 years in age were 10–50% less than those of the grassland, and the N2O emissions from the cropland soil 50 years in age were 10–30% greater than the grassland. When the seasonal emissions were correlated against single soil parameter, the key soil parameter that affected N2O emissions over the entire growing season was the soil moisture content. When the interactions among soil parameters were considered, the amount of N2O emissions could be quantitatively described by a linear combination of two soil variables, the soil ammonium nitrogen (NH4+-N) and moisture concentrations. This study demonstrates how the time of land use conversion from grassland to cropland can positively or negatively affect N2O emission.

Wavelet analysis of spring climate characteristics in arid aeolian area of agro-pastoral ecotone in China

The unique regional climate characteristics are among the main reasons for the frequent wind-sand activity in arid and cold areas in the agro-pastoral ecotone in Inner Mongolia, China. This paper focuses on the time series of temperature and precipitation in spring when sandstorms often occur in the area. Based on meteorological data for a 46-year period from 1959 to 2004, multi-scale variations and abrupt changes in temperature and precipitation were analyzed with the Mexican hat function (MHF) wavelet method, showing the multi-scale variation characteristics of temperature and precipitation, as well as the periods and change points at different time scales. The relationship between temperature and precipitation was obtained using the wavelet analysis method. Obvious staggered features of the variations of spring temperature and precipitation were observed in this agro-pastoral ecotone. The strongest oscillation periods of spring temperature variations were 1 and 22 years, while for precipitation, the strongest oscillation periods of variations were 2, 8, and 22 years. In addition, lower spring temperature corresponded to lower precipitation, whereas higher temperature yielded higher precipitation rate.

Assessment of crop growth and water productivity for five C3 species in semi-arid Inner Mongolia

Water availability is a key biophysical factor determining agricultural production potential. The FAO crop water response model AquaCrop was developed to estimate crop production under water limiting conditions. This model uses the normalized water productivity, WP* (gm−2d−1), to estimate the attainable rate of crop growth under water limitation. In this study we assessed the value and the consistency of WP* under the semi-arid growing conditions of Inner Mongolia. Field experiments on productivity and water use of oats (Avena sativa), sunflower (Helianthus annuus), vetch (Vicia sativa), faba bean (Vicia faba) and potato (Solanum tuberosum) were conducted in 2009, 2010 and 2011. Yield, biomass, evaporation and transpiration varied substantially and significantly between crop species and years. Likewise, water use efficiency (WUE) was affected by these factors, including a significant interaction. WUE (units of yield/unit water) varied between years: from 1.1 to 1.3kgm−3 in oats, from 1.5 to 2.6kgm−3 in sunflower, from 0.5 to 1.1kgm−3 in the two legumes and from 3.1 to 4.4kgm−3 in potato (DM yields). Normalized water productivity did not vary significantly between crop species and years or their interaction, showing an overall value of 14.0±0.32gm−2d−1 in an overarching regression pooling all the data. We conclude that WP* differs from the conventional parameter for water productivity, but is a useful parameter for assessing attainable rate of crop growth and yield in the agro-pastoral ecotone of Inner Mongolia.

Changes in soil carbon stocks and related soil proper-ties along a 50-year grassland-to-cropland conversion chronosequence in an agro-pastoral ecotone of Inner Mongolia, China

Land use change significantly influences soil properties. There is little information available on the long-term effects of post-reclamation from grassland to cropland on soil properties. We compared soil carbon (C) and nitrogen (N) storage and related soil properties in a 50-year cultivation chronosequence of grassland in the agro-pastoral ecotone of Inner Mongolia. Field surveys on land use changes during the period of 1955-2002 were conducted to build a chronosequence of cropland of different ages since the conversion from grassland. The results showed that soil C and N storage, soil texture, and soil nutrient contents varied with land use types and cropland ages (P<0.01). In the 0-30 cm soil layer, the soil organic carbon (SOC) density was significantly lower in the crop- lands (3.28 kg C/m 2 for C50 soil) than in the grasslands (6.32 kg C/m 2 ). After 5, 10, 15, 20, 35, and 50 years of crop planting (years since the onset of cultivation), the SOC losses were 17%, 12%, 19%, 47%, 46%, and 48%, respec- tively, compared with the grasslands. The soil total nitrogen (TN) density of the grasslands was 65 g N/m 2 , and TN density of the cropland soil was 35 g N/m 2 after 50 years of crop planting. Both the SOC and TN densities could be quantitatively determined by a negative exponential function of cropland age (P<0.0001, R 2 =0.8528; P<0.0001, R 2 =0.9637). The dissolved organic carbon (DOC) content, soil available potassium (AK) content, clay content, and pH value were decreased; and the soil bulk density and sand content were increased since the conversion of grassland into cropland during the 50-year period. Our results show soil nutrients were higher in grassland than in cropland. The conversion of grasslands to croplands induced a loss of soil C storage and changes of related soil properties. The reclamation time of cultivated soil (cropland age) had significant effects on soil properties in the study area.