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Grasslands of northern China are of great ecological, economic, and cultural importance (Kang et al. 2007). These immense grasslands cover 400 million ha or 40% of the land area of China and stretch 4 500 km northeast–southwest (lat 28 u N to lat 51 u N). They extend from the northeastern plains adjacent to Mongolia to the southern Tibetan Plateau and consist of four major types: meadow steppes, typical steppes, desert steppes, and alpine steppes (Sun 2005; Kang et al. 2007). Inner Mongolia has 87 million ha of natural grassland, which is a significant constituent of the Eurasian Steppe—the largest contiguous biome in the world (Li 1962, 1979; Wu and Loucks 1992). From east to west, meadow steppe, typical steppe, and desert steppe zones occur in response to the decreasing moisture gradient.
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The Grasslands of Inner Mongolia: A Special Feature
Xingguo Han,
Keith Owens,
X. Ben Wu,
Jianguo Wu,
and Jianhui Huang
Authors are
Professors, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People’s Republic of China;
Professor and Head, Department
of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK 74078, USA;
Professor, Department of Ecosystem Science
and Management, Texas A&M University, College Station, TX 77843, USA; and
Professor, School of Life Sciences and Global Institute of Sustainability,
Arizona State University, Tempe, AZ 85287, USA.
Grasslands of northern China are of great ecological, economic,
and cultural importance (Kang et al. 2007). These immense
grasslands cover 400 million ha or 40% of the land area of China
and stretch 4 500 km northeast–southwest (lat 28uNtolat
51uN). They extend from the northeastern plains adjacent to
Mongolia to the southern Tibetan Plateau and consist of four
major types: meadow steppes, typical steppes, desert steppes, and
alpine steppes (Sun 2005; Kang et al. 2007). Inner Mongolia has
87 million ha of natural grassland, which is a significant
constituent of the Eurasian Steppe—the largest contiguous biome
in the world (Li 1962, 1979; Wu and Loucks 1992). From east to
west, meadow steppe, typical steppe, and desert steppe zones
occur in response to the decreasing moisture gradient (Fig. 1).
Substantial land use change and ecosystem degradation have
occurred within the Inner Mongolia grassland over the last half
century, which has resulted in significant ecological and
socioeconomic consequences at both local and regional scales
(National Research Council 1992; Tong et al. 2004; Jiang et al.
2006). The primary ecological problem is land degradation,
which is attributable mainly to overgrazing and land conver-
sion. Land degradation has led to the deterioration of
biodiversity and ecosystem function and services as well as a
myriad of environmental and economic problems such as sand
storms and poverty. Overgrazing, as the primary cause of land
degradation, is a result of improper land management practices
and the exceedingly large population density of domesticated
animals (Jiang et al. 2006).
Substantial research has been conducted on the ecology and
management of China’s grasslands (see a recent review by Kang et
al. 2007), including early vegetation surveys by Russian, Japanese,
and Western explorers (pre-1950s); systematic natural resource
inventory through surveys of vegetation, soils, and topography by
the Chinese Academy of Sciences and collaborating institutions
(1950–1975); long-term monitoring and studies of grassland
ecosystem structure and function through the establishment of
field research stations (1976–1995); and most recently (since
1996) the expansion of experimental studies of community
dynamics, ecosystem function, and global change that are
increasingly multiscale and multidisciplinary in nature (National
Research Council 1992; Kang et al. 2007). These studies should
be of great interest to the readers of Rangeland Ecology &
Management in other parts of the world. A large number of these
studies, however, have been published in Chinese and are not
readily accessible to non-Chinese readers, although the number of
papers published in English journals has increased rapidly in
recent years (e.g., Niu et al. 2003; Yamano et al. 2003; Zhang et
al. 2003; Bai et al. 2004; Chen at al. 2004; Kang et al. 2004; Wang
et al. 2006; Zhou et al. 2006). The expanse and diversity of these
grasslands make them significant ecologically and their manage-
ment has large regional and global implications. A great deal more
research is needed for better understanding the dynamics of the
social–ecological systems in these areas and for improving policy
and management measures to achieve grassland sustainability.
We present this special feature with a small sample of the
grassland research in China and hope that it will promote greater
awareness of these vast rangelands. This has grown out of the
efforts of a symposium at a Society for Range Management
(SRM) annual meeting on ‘‘Grasslands of Northern China:
Ecology and Contemporary Issues’’ cosponsored by the SRM
International Affairs Committee and the Institute of Botany of
the Chinese Academy of Sciences (CAS), with partial support
from Dow AgroSciences. Through both the symposium and this
special feature, we want to encourage additional research
collaboration on the ecology and management of the grasslands
of China. The special feature includes six studies conducted in the
grassland regions of Inner Mongolia, China. Most of these
studies were conducted at field research stations operated by the
Institute of Botany of the CAS.
Four of the studies focused on the ecology of the typical
steppe grassland and the effects of rangeland management
practices. Ping Liu et al. (this issue) investigated decomposition
rates and nutrient dynamics of leaf, stem, and root litter of five
common plant species in the typical steppe and explored the
potential impact of grazing-induced changes in plant species
composition on ecosystem function at the Duolun Restoration
Ecology Research Station. Baoyin and Li (this issue) reported
the results of a long-term (24-yr) monitoring study, at the
Grassland Ecosystem Research Station of CAS, on the
effectiveness of rangeland management practices (shallow
plowing and harrowing) on the restoration of degraded Leymus
chinensis grassland. Huajie Liu et al. (this issue) evaluated the
effects of grazing intensity on the cover, species composition,
and nitrogen fixation of biological soil crusts in a 16-yr grazing
study also conducted at the Grassland Ecosystem Research
Station. The study of Liang et al. (this issue) focused on grazing
impacts on the vegetation dynamics along a grazing gradient
radiating from residential areas around the Keshiketeng
Banner, Chifeng Prefecture, in northeastern Inner Mongolia.
The other two studies were conducted at the Ordos Sandland
Ecological Research Station of CAS, focusing on fragile
grassland ecosystems and the desertification process. Zhu et
al. (this issue) investigated the responses of seed germination
and seedling growth to sand burial of two dominant perennial
Correspondence: Dr X. Ben Wu, Ecosystem Science and Management, Texas A&M
University, College Station, TX 77843, USA. Email:
Rangeland Ecol Manage 62:303–304
July 2009
grasses in Mu-Us sandland. Li et al. (this issue) explored the
environmental constraints on the productivity of the sandland
plant communities dominated by Artemisia ordosica on sand
dunes of different mobility. Both contributed to the knowledge
base essential for combating desertification and for ecological
restoration of the sandland ecosystems.
We hope that the papers in this special feature will be
followed by many quality publications in Rangeland Ecology
& Management addressing the grasslands of China. It is also
our hope to encourage greater international collaborations of
rangeland and social scientists leading to better understanding
and sustainability of these and other rangeland ecosystems
throughout the world.
BAI, Y., X. HAN,J.WU,AND L. LI. 2004. Ecosystem stability and compensatory
effects in the Inner Mongolia grassland. Nature 431:181–183.
CHEN, S., Y. BAI,L.ZHANG,AND X. HAN. 2004. Comparing physiological responses of
two dominant grass species to nitrogen addition in Xilin River Basin of China.
Environmental and Experimental Botany 53:65–75.
JIANG, G., X. HAN,AND J. WU. 2006. Restoration and management of the Inner
Mongolia grassland require a sustainable strategy. Ambio 35:269–270.
analysis of large-scale gene expression correlated to the phase changes of the
migratory locust. Proceedings of the National Academy of Sciences of the
United States of America 101:17611–17615.
KANG, L., X. HAN,Z.ZHANG,AND O. J. SUN. 2007. Grassland ecosystems in China:
review of current knowledge and research advancement. Philosophical
Transactions of the Royal Society B: Biological Sciences 362(1482):
LI, B. 1962. Basic types and eco-geographical principles of the zonal vegetation in
Inner Mongolia. Journal of the Inner Mongolia University 1962(2):42–72.
LI, B. 1979. Characteristics of China’s grasslands. Grasslands of China
NATIONAL RESEARCH COUNCIL [ED]. 1992. Grasslands and grassland sciences in
northern China. Washington, DC, USA: National Academy Press. 320 p.
NIU, S., G. JIANG,Y.LI,GAO,AND M. LIU. 2003. Diurnal gas exchange and superior
resources use efficiency of typical C
species in Hunshandak Sandland, China.
Photosynthetica 41:221–226.
SUN,H.[ED.]. 2005. Ecosystems of China. Beijing, China: Science Press. 1822 p.
TONG, C., J. WU,S.YONG,J.YANG,AND W. YONG. 2004. A landscape-scale
assessment of steppe degradation in the Xilin River Basin, Inner Mongolia,
China. Journal of Arid Environments 59:133–149.
WANG, C., S. WAN,X.XING,L.ZHANG,AND X. HAN. 2006. Temperature and soil
moisture interactively affected soil net N mineralization in temperate grassland
in northern China. Soil Biology & Biochemistry 38:1101–1110.
WU, J., AND O. L. LOUCKS. 1992. Xilingele grassland. In: National Research Council
[ED.]. Grasslands and grassland sciences in northern China. Washington, DC,
USA: National Academy Press. p. 67–84.
YAMANO, H., J. CHEN,AND M. TAMURA. 2003. Hyperspectral identification of grassland
vegetation in Xilinhot, Inner Mongolia, China. International Journal of Remote
Sensing 24:3171–3178.
ZHANG, Y., Z. ZHANG,AND J. LIU . 2003. Burrowing rodents as ecosystem engineers:
the ecology and management of plateau zokors Myospalax fontanierii in
alpine meadow ecosystems on the Tibetan Plateau. Mammal Review
ZHOU, Z., O. J. SUN,J.HUANG,Y.GAO,AND X. HAN. 2006. Land use affects the
relationship between species diversity and productivity at the local scale in a
semi-arid steppe ecosystem. Functional Ecology 20:753–762.
Figure 1. The types and spatial extents of grassland ecosystems and
other vegetation types in Inner Mongolia, China.
304 Rangeland Ecology & Management
... Grasslands cover more terrestrial area than any other single biome type (Blair, Nippert, & Briggs, 2014). Steppes are the most conspicuous grassland type, and a high proportion of them have suffered from overgrazing (Blair et al., 2014;MA, 2005;Han, Owens, Wu, Wu, & Huang, 2009). Accordingly, the need to cease grazing in steppe ecosystems has now become widely recognized (Blair et al., 2014;Han et al., 2009). ...
... Steppes are the most conspicuous grassland type, and a high proportion of them have suffered from overgrazing (Blair et al., 2014;MA, 2005;Han, Owens, Wu, Wu, & Huang, 2009). Accordingly, the need to cease grazing in steppe ecosystems has now become widely recognized (Blair et al., 2014;Han et al., 2009). Postgrazing succession may become an important transition in steppe areas. ...
Question Steppes may be sensitive to rainfall and nitrogen (N) pulses; however, their potential effects on local colonization and extinction during postgrazing steppe succession have not been thoroughly elucidated to date. We addressed how increased rainfall and N influenced plant species richness, gain, loss, and turnover in an ungrazed steppe. Location Northeastern Inner Mongolia, China. Methods We performed a five‐growing‐season field experiment, in which an ungrazed steppe was subject to nine different combinations of rainfall and N. The three rainfall levels were ambient amount of rainfall, a 14% increase in amount of rainfall, and a 28% increase in amount of rainfall; the three N levels were no N addition, an addition of 5 g N m⁻² year⁻¹, and an addition of 10 g N m⁻² year⁻¹. We determined successional changes at the taxonomic and functional levels by surveying plant species in the first and fifth growing seasons. Results (a) Increased rainfall and N addition did not affect plant species richness but did influence plant species loss, gain, and turnover. (b) At the taxonomic level, species loss, gain, and turnover decreased monotonically with increasing rainfall; N addition decreased species loss and turnover but did not influence species gain; the slope of the species loss–gain relation was approximately 1.0. (c) At the plant functional group level, increased rainfall favored C3 plants by sustaining species gain and decreasing species loss; N addition favored C4 plants by increasing the species gain and decreasing the species loss. Conclusion Increased rainfall and simulated N deposition could induce rapid colonization and extinction during postgrazing steppe succession, but maintain plant diversity homeostasis by equally affecting species colonization and extinction. Future rainfall enrichment and N deposition might strongly influence the relative abundance of different plant functional groups, thereby affecting successional changes under global change.
... The Inner Mongolian grassland, part of the Eurasian grassland biome (Han et al. 2009;Fang et al. 2015;, is an ideal system to study the interactive effects of land use and precipitation on soil carbon cycling. Grazing and mowing are widely practiced land-use regimes (Lu et al. 2015;Fang et al. 2015;Wang et al. 2020a), and precipitation is often considered the most important climatic driver of R s in Inner Mongolian grasslands (Yang et al. 2020;Li et al. 2020). ...
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Purpose Grasslands are facing the threat of climate change and intensive land use. Soil respiration (Rs) in grassland ecosystems can be potentially altered by changes in precipitation and land use. We aimed to quantify the impact of changes in precipitation and common land use practices in an Inner Mongolia grassland, i.e., mowing and grazing, on soil respiration. Methods We performed an in situ experiment with altered precipitation (+ 50%, ambient, and -50%) and land use (control or fencing, mowing, and grazing) to explore their impacts on soil respiration and its autotrophic (Ra) and heterotrophic (Rh) components. Results Altered precipitation had stronger impacts on abiotic and biotic drivers than land use, leading to stronger impacts on Rs and its components. Over the 3-year experiment, Rs, Ra and Rh decreased by 36%, 42% and 33% with reduced precipitation and increased by 29%, 36% and 25% with increased precipitation, respectively. Grazing and mowing caused relatively small decreases in Rs compared to fencing (generally < 10%). However, precipitation and land use interactively impacted abiotic and biotic drivers and thus Rs. The decrease in Rs with reduced precipitation was greater with grazing (38%) and mowing (37%) than with fencing (32%). Conclusions Rs and its components may decrease under the projected decrease in precipitation and may further decrease with grazing and mowing compared to fencing. Therefore, land use should be considered when predicting grassland carbon cycling in response to future precipitation changes.
... We conducted this study in northeast Inner Mongolia, China (Fig. 1). The study site consists mainly of three vegetation zones: the temperate coniferous and deciduous forests zone, the meadow steppe zone, and the typical steppe zone (Han et al. 2009, Wu et al. 2015. The region has a temperate climate, with mean annual temperature and yearly precipitation ranging between 6 °C and 7 °C and between 300 and 400 mm, respectively (Wu et al. 2015). ...
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The loss and fragmentation of natural habitats because of anthropogenic activities are major threats to biodiversity worldwide. In recent decades, vast mosaics of natural and seminatural habitats have been transformed into fragmented agricultural landscapes in Inner Mongolia, China, with potential negative effects on avian diversity. We quantified the effect of local and landscape habitat attributes on the taxonomic, functional, and phylogenetic diversity of bird communities in Inner Mongolian grasslands. We considered eight independent habitat variables obtained by variance inflation factor analysis. We used canonical correspondence analysis to determine how these habitat factors of multiple scales explained variance in species composition. We then fitted Bayesian generalized additive models to analyze the habitat-biodiversity relationships and included a smooth effect of land cover richness to test the intermediate disturbance hypothesis in each model. Our results provided evidence that differences in bird assemblages can be explained, in part, by differences in local and landscape-scale habitat features. The responses of the four diversity indices to these predictors were diverse and scale-dependent. We found species richness and Shannon diversity exhibited similar response, with both being negatively related to bare land percentage while being positively related to plant canopy and impervious surface percentage. Phylogenetic diversity was positively associated with plant richness while negatively associated with forest percentage and impervious surface percentage. We found no statistical evidence for a relationship between functional diversity and any of the variables examined here. Additionally, for the four measures of bird diversity, we did not find any evidence that they peaked at intermediate levels of habitat disturbance. We propose that assessments of regional grassland bird communities should be conducted at multiple scales and that a range of biodiversity metrics are required to better evaluate and inform conservation decision making, especially when the target is preserving not only species but also their evolutionary history and ecological functions.
... Most grasslands in China have suffered from severe degradation due to long-term overgrazing over the past decades (Kang et al. 2007, Wiesmeier et al. 2009). To restore these degraded grasslands, fencing that limits grazing is regarded as an effective and simple method, which has been widely applied in northern China and especially in Inner Mongolia (Han et al. 2009. Plant height, cover, aboveground biomass, and soil nutrients of degraded grasslands have been improved after long-term fencing in Inner Mongolia (Liu et al. 2017, Sagar et al. 2019. ...
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Excess litter accumulates on the soil surface of fenced grasslands and alters the abiotic environment and plant population dynamics. However, little is known about the effect of litter accumulation on the interaction between environmental factors and plant population characteristics in fenced grasslands, especially over different time scales. We applied a three‐year litter removal experiment to two kinds of fenced grasslands in Inner Mongolia, China. We measured soil temperature in situ and plant phenology and population characteristics of three dominant species (Stipa grandis, S. krylovii, and Leymus chinensis). During the growing season, litter accumulation (i.e., the control) significantly decreased soil temperature, with a larger effect in the daytime than at night. The diurnal negative effect gradually weakened across the growing season, whereas the negative effect in the nighttime shifted to a positive effect on soil temperature in the late growing season. The decreased soil temperature delayed plant phenology, with longer delays in S. grandis and S. krylovii than L. chinensis. Litter accumulation also significantly increased the height, cover, root biomass, and relative dominance of L. chinensis but decreased cover, density, root biomass, and relative dominance of both Stipa, driving replacement of S. grandis or S. krylovii by L. chinensis in two grasslands. Our findings emphasize the critical function of litter in grassland management and provide a new insight to elucidating the mechanism of how litter accumulation regulates the abiotic environment, community composition and structure, and successional change in fenced grasslands.
... Ecologicаl аnd finаnciаl evаluаtion of destruction аreа due to mining аctivities should be mаde prior to the commencement of minerаl explorаtion аnd mining аctivites (Gao et al., 2016;Fisher, 2008;Boyd et al., 2009). Аccording to this, such prior estimаtions hаve following positive impаcts: 1) prevent risk of further ecologicаl аnd finаnciаl dаmаge to mining compаnies, 2) invest in modern environmentаlly friendly techniques аnd technologies, 3) sаve huge аmount of money spend by stаte budget on rehаbilitаtion of аlreаdy dаmаged environment (Han et al., 2009). This pаper will cover а methodology for evаluаtion of finаnciаl dаmаge to environment from the mining industry. ...
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Аim of this study wаs to cаlculаte economic vаlue of destructed lаnd in Mongoliа in order to fаcilitаte restorаtion of mining аreа. Totаl economic vаlue is а universаl frаmework for estimаting аnd evаluаting economicаl dаmаge cаuse to environment due to mining аctivities аnd other technogenic production аctivities. Compensаtion for environmentаl аnd finаnciаl dаmаge cаn be determined bаsed on the following three cаtegories: initia restoration, restoration by compensation and evaluation of ecological damage. Main object of this study is direct economic vаlue of destructed environment due to Tumurtei iron ore mine аctivity. Аll estimаtions in this pаper аre mаde аccording to Mongoliаn legislаtion аnd lаws. During thаt project а totаl of 511.9 hectаres of аreа аre exposed to environment destruction. Estimаtion of ecologicаl dаmаge аre consisting of following pаrts: dаmаge to soil, dаmаge to surfаce аnd groundwаter resources, dаmаge to forest resources, dаmаge to vegetаtion аnd dаmаge to аnimаl fаunа. The аssessment of ecologicаl аnd finаnciаl dаmаge to the environment is performer in following stаges: 1. determine the аmount of potentiаl dаmаge to the environment; 2. cаlculаte аnd determine the аmount of dаmаge reduced аs а result of meаsures to reduce or eliminаte dаmаge to the environment during production аctivities; 3. estimаte the аmount of аctuаl dаmаge resulting from the operаtion. Results of this study concerning interests of mining entities аnd public entities, who аre in chаrge of regulаting such аctivities.
... It is well known that the steppe ecosystem is one of the dominate ecosystems in China. It covers 40% of the national land area and about 78% of this ecosystem (313 × 10 4 km 2 ) is located in northern China (Han, Owens, Wu, Wu, & Huang, 2009;Kang et al., 2007). Soil R h processes under warming conditions in the temperate steppe ecosystem would strongly impact on ecosystem functions in northern China as the temperature in this region may continue to increase in the 21st century. ...
There has been an active debate among ecologists about the mechanisms of ephemeral response of soil respiration to climate change. The key questions are whether soil microbes would reduce their physiological rates (thermal acclimation) under warmer temperature regime,and what are the mechanisms. Using a long‐term warming field experiment, we explored the thermal acclimation of soil heterotrophic respiration (Rh) in a temperate steppe ecosystem in Inner Mongolia, China. A thermal acclimation mechanism, namely change in lipid composition of soil microbes, was also tested in this study. Our results showed that six years of warming treatment had significantly decreased soil mass‐specific respiration (substrate Rmass), indicating soil Rh would acclimate to long‐term warming. In addition, we found that this thermal acclimation presented the type II acclimation. Because experimental warming significantly decreased substrate Rmass but not the Q10 values. Furthermore, we also found that long‐term experimental warming had already increased the carbon numbers of the fatty acids in soil microbial membranes at the community level. In summary, our results indicated that soil Rh could acclimate to global warming via modifying cell membrane constitutions and these mechanisms would play vital roles in the near future. This article is protected by copyright. All rights reserved.
... (2) Plowing, seeding, and fertilizing jointly increase plant species diversity, plant functional groups, and community biomass production; if so, this joint effect might be greater than the effect of any individual practices. To test these two hypotheses, we conducted an experiment over two growing seasons in an Inner Mongolian degraded steppe, which is characterized by susceptibility to disturbances and low productivity (Han et al., 2009). We measured a suite of response variables: plant species richness, loss, gain, and turnover; the relative abundance of grasses, non-legume forbs, and legume forbs, and aboveground plant community biomass. ...
... Although institutions differ in IM and MG, land conversion from grassland to croplands, urbanization and mining has reduced the extent of rangeland cover and has fragmented ecosystems across the Plateau (Cao et al 2013, Tuvshintogtokh andAriungerel 2013). Species composition and biodiversity are declining in both IM (Han et al 2009) and MG (Khishigbayar et al 2015, Jamiyansharav et al 2018, leading to widespread concern about pasture degradation. However, degradation is rarely defined in a meaningful way in public discourse, fueling debate and misconceptions about current conditions (Addison et al 2012). ...
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The Mongolian Plateau hosts two different governments: the Mongolian People's Republic and the Inner Mongolia Autonomous Region, a provincial-level government of the People's Republic of China. The divergence between these governments has widened in the past century, mostly due to a series of institutional changes that generated different socioeconomic and demographic trajectories. Due to its high latitude and altitude, the Plateau has been highly sensitive to the rapid changes in global and regional climates that have altered the spatial and temporal distributions of energy and water. Based on a recent workshop to synthesize findings on the sustainability of the Plateau amidst socioeconomic and environmental change, we identify five critical issues facing the SES: 1) divergent and uncertain changes in social and ecological characteristics; 2) declining prevalence of nomadism; 3) consequences of rapid urbanization in transitional economies; 4) the unsustainability of large-scale afforestation efforts in the semi-arid and arid areas of Inner Mongolia; and 5) the role of institutional changes in shaping the SES on the Plateau. We emphasize that lessons learned in Inner Mongolia are valuable, but may not always apply to Mongolia. National land management policies and regulations have long-term effects on the sustainability of SES; climate change adaptation policies and practices must be tuned to local conditions and should be central to decision-making on natural resource management and socioeconomic development pathways.
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Purpose Changes in precipitation amount and land use are expected to greatly impact soil respiration (Rs) of grasslands, but little is known about whether they can interactively impact Rs and how plant and soil microbial communities regulate the Rs response. Methods We investigated the impacts of altered precipitation amount (–50%, ambient and + 50%) and land use (fencing, mowing and grazing) on autotrophic (Ra), heterotrophic (Rh) and total Rs as well as their abiotic and biotic drivers with a field experiment in the Inner Mongolian grassland. Results Precipitation positively impacted respirations and 50% changes in precipitation leads to more substantial changes in abiotic and biotic drivers, and thus respirations, than land use. We identified the interactive effects and found that, over the 3-year experiment, a 50% decrease in precipitation caused a 31.9% decrease in Rs under fencing, but a 38.4% and a 37.2% decrease under grazing and mowing, respectively. Conclusions Our results indicate that taking the more intensive land use into consideration can precisely predict grassland carbon cycling in responding to future precipitation changes. In addition, chronically shifted plant and soil microbial communities under changing precipitation and land use may regulate the long-term responses of carbon cycling in grasslands.
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Purpose: Changes in precipitation amount and land use are expected to greatly impact soil respiration (Rs) of grassland ecosystems. However, little is known about whether they can interactively impact Rs and how plant and soil microbial communities regulate the response of Rs. Methods: Here, we investigated the impacts of altered precipitation amount (–50%, ambient and +50%) and land-use regime (fencing, mowing and grazing) on Rs with a field experiment in the Inner Mongolian grassland. Results: We found that altered precipitation amount impacted Rs and its components across the 3-year study period, while land-use regime alone or its interaction with precipitation amount impacted them in certain years. In addition, changed soil microclimate, especially soil moisture, under altered precipitation amount and land-use regime can impact the components of Rs either directly or indirectly via influencing plant and soil microbial communities. Conclusions: Integrating changing precipitation amount and land-use regime within experiment can produce more accurate insights into grassland Rs, and chronically shifted plant and soil microbial communities under these changes may result in distinct long-term impacts on Rs.
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Summary 1. The accelerating extinction rate of plant species and its effect on ecosystem functioning is a hotly debated topic in ecological research. Most research projects concerning the relationship between species diversity and productivity have been conducted in artificial plant communities, with only a few in natural ecosystems. In this study we examined the relationship between species diversity and above-ground net primary productivity (ANPP) over two consecutive growth seasons (2004 and 2005) in a semi-arid steppe ecosystem of northern China, that were subjected to different land uses. 2. Land use affected the relationship between species diversity and ANPP in this semi-arid steppe ecosystem. Exclusion of grazing without or with biomass removal by mowing increased ANPP, species richness and species diversity compared with free grazing; the effect was reflected mainly as enhanced importance of the perennial forbs functional group in terms of their relative contributions to ANPP, plant cover and plant abundance. 3. Many mechanisms regulate the relationship between species diversity and produc- tivity. Differential effects of anthropogenic activities on biodiversity and ecosystem functioning greatly complicate the analysis of such relationships. On grazing-exclusion sites the relationship between ANPP and species richness can be best described as an exponential growth function ( R 2 = 0·99, P < 0·001, n = 24); whereas on the free-grazing site the relationship takes the form of exponential decay ( R 2 = 0·96, P < 0·001, n = 24).
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Net photosynthetic rate (P N), transpiration rate (E), stomatal conductance (g s), leaf water potential (ψleaf), leaf nitrogen content, and photosynthetic nitrogen use efficiency (PNUE) were compared between a typical C4 plant, Agriophyllum squarrosum and a C3 plant, Leymus chinensis, in Hunshandak Sandland, China. The plant species showed different diurnal gas exchange patterns on June 12–14 when photosynthetic photon flux density (PPFD), air temperature (T air), and water potential were moderate. P N, E, and g s of A. squarrosum showed distinct single peak while those of L. chinensis were depressed at noon and had two peaks in their diurnal courses. Gas exchange traits of both species showed midday depression under higher photosynthetic photon flux density (PPFD) and T air when Ψleaf was significantly low down on August 6–8. However, those of A. squarrosum were depressed less seriously. Moreover, A. squarrosum had higher P N, Ψleaf, water use efficiency (WUE), and PNUE than L. chinensis. Thus A. squarrosum was much more tolerant to heat and high irradiance and could utilise the resources on sand area more efficiently than L. chinensis. Hence species like A. squarrosum may be introduced and protected to reconstruct the degraded sand dunes because of their higher tolerance to stress and higher resource use efficiency.
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Intact soil cores from three adjacent sites (Site A: grazed, Site B: fenced for 4 years, and Site C: fenced for 24 years) were incubated in the laboratory to examine effects of temperature, soil moisture, and their interactions on net nitrification and N mineralization rates in the Inner Mongolia grassland of Northern China. Incubation temperature significantly influenced net nitrification and N mineralization rates in all the three grassland sites. There were no differences in net nitrification or N mineralization rates at lower temperatures (−10, 0, and 5 °C) whereas significant differences were found at higher temperatures (15, 25, and 35 °C). Soil moisture profoundly impacted net nitrification and N mineralization rates in all the three sites. Interactions of temperature and moisture significantly affected net nitrification and mineralization rates in Site B and C, but not in Site A. Temperature sensitivity of net nitrification and N mineralization varied with soil moisture and grassland site. Our results showed greater net N mineralization rates and lower concentrations of inorganic N in the grazed site than those in the fenced sites, suggesting negative impacts of grazing on soil N pools and net primary productivity.
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The two dominant species, Leymus chinensis and Stipa grandis have different distribution area in the Xilin River Basin: relatively wet and fertile for L. chinensis and dryer and leaner for S. grandis. Different photosynthetic physiology traits and resource use efficiency might contribute to the distribution pattern of two species in heterogeneous habitats. In this study, the plant nitrogen (N) content, C/N ratio, values and photosynthetic characteristics of L. chinensis and S. grandis were measured at five different N addition rates. We found that N addition resulted in significant increase in N concentration of plant tissues and decrease in C/N ratio of the two species; L. chinensis had higher N concentration and lower C/N ratio than S. grandis. Increasing N addition rates enhanced the maximum photosynthetic rate (Am) of L. chinensis, whereas Am of S. grandis responded only to low N supply rates. Nitrogen addition led to a decrease in the maximum apparent quantum yield (Φm) but had little effect on the light compensation point (LCP) and the light saturation point (LSP) of the two species. Varying N addition rates did not alter the gas exchange characteristics including net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), and intercellular CO2 concentration (Ci). A and gs of L. chinensis were consistently and considerably higher than those of S. grandis with and without N addition. Although there were no significant effects of N supply on the instantaneous water-use efficiency (WUEi), the values of L. chinensis were significantly higher with increased N addition rates. A closely positive correlation was found between and WUEi in the two species. Our results suggested that contrasting physiological strategies were employed to adapt to drought by two plant species, i.e., high A and E for L. chinensis versus low A and E for S. grandis; L. chinensis achieved higher WUE at the expense of decreasing nitrogen use efficiency (NUE), whereas, S. grandis could simultaneously maintain relative higher WUE and NUE. This interspecific difference in the trade-off of plasticity between NUE and WUE may partially explain the regional distribution of those two species in relation to the moisture and nutrient availability.
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Numerous studies have suggested that biodiversity reduces variability in ecosystem productivity through compensatory effects; that is, a species increases in its abundance in response to the reduction of another in a fluctuating environment. But this view has been challenged on several grounds. Because most studies have been based on artificially constructed grasslands with short duration, long-term studies of natural ecosystems are needed. On the basis of a 24-year study of the Inner Mongolia grassland, here we present three key findings. First, that January-July precipitation is the primary climatic factor causing fluctuations in community biomass production; second, that ecosystem stability (conversely related to variability in community biomass production) increases progressively along the hierarchy of organizational levels (that is, from species to functional group to whole community); and finally, that the community-level stability seems to arise from compensatory interactions among major components at both species and functional group levels. From a hierarchical perspective, our results corroborate some previous findings of compensatory effects. Undisturbed mature steppe ecosystems seem to culminate with high biodiversity, productivity and ecosystem stability concurrently. Because these relationships are correlational, further studies are necessary to verify the causation among these factors. Our study provides new insights for better management and restoration of the rapidly degrading Inner Mongolia grassland.
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The migratory locust is one of the most notorious agricultural pests that undergo a well known reversible, density-dependent phase transition from the solitary to the gregarious. To demonstrate the underlying molecular mechanisms of the phase change, we generated 76,012 ESTs from the whole body and dissected organs in the two phases. Comparing 12,161 unigene clusters, we identified 532 genes as phase-related (P < 0.01). Comprehensive assessment of the phase-related expression revealed that, whereas most of the genes in various categories from hind legs and the midgut are down-regulated in the gregarious phase, several gene classes in the head are impressively up-regulated, including those with peptidase, receptor, and oxygen-binding activities and those related to development, cell growth, and responses to external stimuli. Among them, a superfamily of proteins, the JHPH super-family, which includes juvenile hormone-binding protein, hexamerins, prophenoloxidase, and hemocyanins, were highly expressed in the heads of the gregarious hoppers and hind legs of the solitary hoppers. Quantitative PCR experiments confirmed in part the EST results. These differentially regulated genes have strong functional implications that numerous molecular activities are involved in phase plasticity. This study provides ample molecular markers and genomic information on hemimetabolous insects and insights into the genetic and molecular mechanisms of phase changes in locusts. • solitary phase • gregarious phase • EST • unigene
Derivative spectroscopy of hyperspectral reflectance data of grassland vegetation was used to extract the wavelength peaks of different grass species of Xilinhot, Inner Mongolia, China. Caragana microphylla, which is characteristic of dry areas, was successfully detected among the four dominant grass species found in the typical Xilinhot grassland, using fourth-derivative peaks around 670 nm and 720 nm. A radiative transfer simulation showed that the identification scheme was not distorted by the atmosphere during airborne remote sensing. This suggests that high-order derivative spectroscopy of hyperspectral reflectance data from grassland vegetation can be an effective tool for advanced mapping and for the monitoring of grasslands.
1. Plateau zokors, Myospalax fontanierii, are the only subterranean herbivores on the Tibetan plateau of China. Although the population biology of plateau zokors has been studied for many years, the interactions between zokors and plants, especially for the maintenance and structure of ecological communities, have been poorly recognized. In the past, plateau zokors have been traditionally viewed as pests, competitors with cattle, and agents of soil erosion, thus eradication programmes have been carried out by local governments and farmers. Zokors are also widely and heavily exploited for their use in traditional Chinese medicine. 2. Like other fossorial animals, such as pocket gophers Geomys spp. and prairie dogs Cynomys spp. in similar ecosystems, zokors may act to increase local environmental heterogeneity at the landscape level, aid in the formation, aeration and mixing of soil, and enhance infiltration of water into the soil thus curtailing erosion. The changes that zokors cause in the physical environment, vegetation and soil clearly affect the herbivore food web. Equally, plateau zokors also provide a significant food source for many avian and mammalian predators on the plateau. Zokor control leading to depletion of prey and secondary poisoning may therefore present problems for populations of numerous other animals. 3. We highlight the important role plateau zokors play in the Tibetan plateau ecosystem. Plateau zokors should be managed in concert with other comprehensive rangeland treatments to ensure the ecological equilibrium and preservation of native biodiversity, as well as the long-term sustainable use of pastureland by domestic livestock.
Steppe degradation is a major ecological and economic problem in the Inner Mongolia steppe region, China because it reduces grassland productivity and leads to desertification. The objective of this study was to assess the spatial extent and severity of steppe degradation in the Xilin River Basin, Inner Mongolia using a landscape-scale approach. Our approach combined information from field survey records, existing vegetation maps, and remote sensing data to determine the different degrees of degradation for diverse steppe communities at the local scale and their spatial pattern at the landscape scale. We also developed a steppe degradation index (SDI) that integrates the information on the spatial extent and severity of steppe degradation. Our results showed that the total area of degraded steppe in this region increased from 7191.3 km2 in 1985 to 7689.3 km2 (72% of the total basin) in 1999. We used SDI to quantify the degree of degradation and its changes in space and time. The SDI maps revealed that large-scale patterns of steppe degradation were related to landform types. For both 1985 and 1999, the four landforms exhibited increasing degrees of degradation in the following order: low mountains > lava tablelands > hills > high plains. Several seriously degraded regions in the Xilin River Basin were identified. This study demonstrates the effectiveness of combining remote sensing data and synoptic ecological indices in assessing ecosystem degradation, and provides useful information for improving grassland management practices and restoring the degraded steppe vegetation in the Xilin River Basin, Inner Mongolia.