Ecosystem stability and compensatory effects in the Inner Mongolia grassland

Bai, Yongfei; Han, Xingguo; Wu, Jianguo; Chen, Zuozhong; Li, Linghao

doi:10.1038/nature02850

Cited by 1,081 publications

(993 citation statements)

References 23 publications

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“…These values were thus consistently above 60 to 80 g/kg DM, regarded as the minimum CP concentration for grazing sheep fed at a maintenance level (Minson, 1990;Van Soest, 1994). It is therefore unlikely that even the lower CP concentrations at the end of the vegetation period induced N deficiencies for rumen microbial activity and, as a consequence, reduced diet digestibility (Van Soest, 1994) and animal feed intake (Moore and Mott, 1973 (Xiao et al, 1995;Bai et al, 2004) and, because of a more rapid plant maturation, herbage quality (Schö nbach et al, 2009). The additional amount of nutrients remaining on the plots, when animals were also present on pastures at night, did not influence HM or composition, neither in dry years nor towards the end of the grazing seasons.…”

Section: Discussionmentioning

confidence: 99%

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Effect of continuous v. daytime grazing on feed intake and growth of sheep grazing in a semi-arid grassland steppe

Müller

Liu

Wang

et al. 2012

Animal

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In the Inner Mongolian steppe, China, sheep generally graze during daytime and are kept in yards overnight. Hence, nutrients are not returned to the grassland, which might reduce its long-term productivity. Furthermore, the restricted grazing time may limit forage intake and thus the performance of sheep. The aim of this study was therefore to evaluate the impact of continuous 24-h grazing (CG) v. the common daytime grazing (DG) on herbage mass (HM), feed quality, feed organic matter intake (OMI) and live weight gain (LWG) of sheep in the Inner Mongolian steppe. Experiments were carried out from July to September, between 2005 and 2007 on two 2-ha plots per grazing treatment. Each month, the external faecal marker titanium dioxide (TiO 2 ) was orally administered to six sheep per plot on 10 consecutive days. Faecal grab samples were obtained from day 6 to 10 and analysed for CP concentrations to estimate digestibility of organic matter (dOM). Faecal TiO 2 concentrations were used to determine the total faecal output and hence OMI of sheep. Concomitant to faeces collection, HM and quality, as well as LWG of the animals were measured. HM and herbage quality did not differ between treatments. However, as the season progressed, concentrations of NDF, ADF and ADL increased, whereas HM and CP concentrations declined. HM and herbage quality parameters differed between years according to the annual precipitation. dOM was similar in CG (0.577) and DG (0.572) sheep, but it decreased from July (0.583) to September (0.558) and differed between years. Accordingly, the OMI of sheep was similar for both treatments across the entire grazing season and all study years. Although mean LWG differed between months and years, it was identical in CG (101.5 g/day) and DG sheep (101.8 g/day). Additional time on pasture during night does not increase feed intake or animal performance. Positive effects of a nutrient reflux on grassland productivity and herbage quality when animals remained on the plots overnight were not found, most likely because of the fact that sheep crowded together in one corner of the plots during darkness and faecal and urinary excretions were thus not evenly distributed across the entire pasture. Considering the risk of animal theft as well as the importance of sheep manure as fuel, the common penning of sheep at night seems to be an adequate management practice for pastoralists in the Inner Mongolian steppe.

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Section: Discussionmentioning

confidence: 99%

“…The experimental site is located within the typical steppe zone (Yu et al, 2004). Dominant plant species are C 3 grasses, including the perennial bunchgrass Stipa grandis and the perennial rhizome grass Leymus chinensis (Xiao et al, 1995;Bai et al, 2004). Plant species compositions on the CG and DG plots are given in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Effect of continuous v. daytime grazing on feed intake and growth of sheep grazing in a semi-arid grassland steppe

Müller

Liu

Wang

et al. 2012

Animal

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“…The main soil type is a dark chestnut soil (equal to the Calciborolls in USDA soil taxonomy system) [21,22] and the soil is sandy loam [23,24]. The main vegetation types are Leymus chinensis and Stipa grandis communities [25]. From the end of April to the end of September is the growth season of grass plants, lasting about 150 days [19].…”

Section: Site Descriptionmentioning

confidence: 99%

CH4 uptake flux of Leymus chinensis steppe during rapid growth season in Inner Mongolia, China

Geng

Luo

Yuan

2010

Sci. China Earth Sci.

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The influence of near ground atmosphere CH 4 concentration, soil water content, soil Eh, plants, soil temperature, and pH on CH 4 uptake flux of Leymus chinensis steppe during rapid growth season was studied using field in-situ measurement in Xilin River basin of Inner Mongolia, China. The results showed that CH 4 uptake flux was positively correlated with near ground atmosphere CH 4 concentration and soil Eh but negatively correlated with soil water content. Precipitation may decrease the CH 4 flux by increasing the soil water content. The average fluxes of three treatments during the observation period were 1.52 (natural conditions, 1.51 (aboveground plants were excluded), and 2.00 mg m −2 d −1 (all plants were removed), respectively. The difference between the CH 4 flux of natural condition treatment and that of removing aboveground plants treatment is small, whereas the flux of removing all plants treatment is larger than the other two treatments. This means that the contribution of aboveground plants to CH 4 uptake flux is smaller than that of roots or roots-removing process. CH 4 uptake flux is not sensitive to soil temperature and the narrow-ranged soil pH (6.36-7.86). The Leymus chinensis steppe acts as a sink for CH 4 , and thus more studies should be focused on its affecting factors and related mechanisms. The global atmospheric concentration of CH 4 has increased from a pre-industrial value of about 715 to 1732 ppb in the early 1990s, and was 1774 ppb in 2005 [1]. CH 4 is a long-lived greenhouse gas (it lasts about 8.4 years in the atmosphere) [2] and can absorb more infrared radiation than CO 2 . The warming potential of CH 4 is 26 times of that of CO 2 [3, 4] and the current direct radioactive forcing of CH 4 is 20% of the total from all of the long-lived and globally mixed greenhouse gases [5]. Emission of CH 4 has a long-term effect on climate change. CH 4 concentration in atmosphere lies mainly on the balance between natural and artificial emission and uptake of CH 4 . The persistently increased CH 4 concentration is caused not only by the increased sources but also by the decreased sink [6]. Aerobic soil environment can oxidize the CH 4 diffusing from atmosphere to soil, which is the biggest sink for CH 4 of terrestrial ecosystem except for atmospheric photochemical reactions [7]. This oxidation process is very important for regulating the quantity of CH 4 in atmosphere. The increase rate of CH 4 concentration in atmosphere would be 1.5 times of value right now if there were no soil sink for CH 4 [8]. Up to now, most of our studies about CH 4 uptake are focused on forest [9-11], grassland [12-14], and paddy field [15,16], and also concerned with the influence of land use change on CH 4 uptake [17,18]. Research on CH 4 uptake process in grassland ecosystem focused on the variation pattern of flux, but its affecting factors are not yet clear.

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“…Nitrogen accumulation through industrial and agricultural processes has dramatic impacts on the biodiversity and ecosystem function (Tilman et al 1996(Tilman et al , 2006Bai et al 2004). A number of studies have shown that the abundance and community structure of AOA and AOB shifted in response to different ammonium concentrations and fertilizers.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen loading levels affect abundance and composition of soil ammonia oxidizing prokaryotes in semiarid temperate grassland

et al. 2011

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Purpose Global nitrogen deposition has profound impact on the terrestrial ecosystem including the semiarid temperate grassland, causing vegetation community shifts and soil acidification. Little is known regarding the effect of nitrogen (N) deposition on the belowground microbial communities. This study aimed to examine the response of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to added N in semiarid temperate grassland. Materials and methods We studied the changes of AOB and AOA by using molecular techniques targeting amoA genes along a urea fertilization gradient, i.e., 0, 1, 2, 4, 8, 16, 32, 64 g N m −2 year −1 , in a 6-year field experiment of semiarid temperate grassland, Inner Mongolia of China. Results and discussion AOB community responded to urea-N substrate clearly, and N addition rates 2-4 g N m −2 year −1 induced an increase in its abundances and the shift of its composition. However, AOA community remained unchanged and the highest N loading at 64 g N m −2 year −1 even decreased its abundance. Moreover, higher N loading rates (more than 16 g N m −2 year −1 ) significantly decreased the diversity of AOB but not AOA, as indicated by the decrease of its Shannon and Evenness indices. Conclusions The relative long-term nitrogen loading of more than 2-4 g N m −2 year −1 resulted in diversity loss of AOB in this semiarid temperate grassland. Increasing N loading altered AOB abundance and composition, but AOA showed nonsignificant changes.

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Ecosystem stability and compensatory effects in the Inner Mongolia grassland

Cited by 1,081 publications

References 23 publications

Effect of continuous v. daytime grazing on feed intake and growth of sheep grazing in a semi-arid grassland steppe

Effect of continuous v. daytime grazing on feed intake and growth of sheep grazing in a semi-arid grassland steppe

CH4 uptake flux of Leymus chinensis steppe during rapid growth season in Inner Mongolia, China

Nitrogen loading levels affect abundance and composition of soil ammonia oxidizing prokaryotes in semiarid temperate grassland

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