**1.**

## **Table**

*Correlation analysis of environmental variables with each other and with response ratio of SCP [*RR*(SCP)] and SNP [*RR*(SNP)] of surface soil (<15 cm).*

#### *Effects of Grazing Intensity on Belowground Carbon and Nitrogen Cycling DOI: http://dx.doi.org/10.5772/intechopen.90416*

*Grasses and Grassland Aspects*

exhibited positive effects on SNP at the depth of >15 cm, while both moderate and heavy grazing had the opposite effects on it at the same depth (**Figure 6**). These differences induced by livestock type, climate type and soil depth may results from the complex interaction between grazing intensity with water, temperature and nutrients, but the potential mechanisms was still unknown and need further

*Relationships of grazing duration (a, b), mean annual temperature (MAT, c, d), and mean annual precipitation (MAP, e, f) with response ratios (RR) of soil carbon pools (SCP, a, c, e) and soil nitrogen pools* 

Overgrazing is a primary contributor to grassland degradation and desertification, which may significantly affect ecosystems functions and then lead to positive or negative climate-biosphere feedbacks [8, 25]. The regional and global studies showed that grazing intensity is a very important role in regulating belowground C and N pools and fluxes, which may offer some suggestions for future grassland management and model development. First, the effects of grazing intensity on C and N cycles may be regulated by environmental conditions (e.g., nitrogen and water availability; [8]). However, how the interactions of grazing with global change factors (e.g., warming, nitrogen addition, elevated CO2, increased precipitation and drought) is influenced by grazing intensity remain unknown [44, 45]. These knowledge gaps may impede us to fully understand how grazing affects C

Second, current global synthesized studies showed that most of current grazing studies were distributed in temperate climates, such as eastern Asia and North America, and only few studies were conducted in cold and tropical regions [5, 6]. Thus, more studies from other regions (e.g., Africa and Australia) should be conducted in order to develop a more comprehensive understanding of how grazing intensity influence C and N cycling of global grasslands. Another problem is the experimental duration. Most of current grazing experiments were less than 10 years, due to the high costs and long time scale. The grazing effects on C and N cycle may vary with time [5]. Hence, there is a need to conduct studies over one decade to bet-

ter understand the effects of grazing on belowground C and N cycling.

**102**

investigations.

**Figure 7.**

*(SNP, b, d, f).*

**4. Implication for grassland management**

and N cycles of grasslands at global scale.

Third, grazing intensity (light, moderate, and heavy grazing) significantly affects belowground C and N cycling in grassland ecosystems. Meanwhile, different combinations of grazing and global change factors (e.g., warming, nitrogen addition) also have disparate effects on C and N cycle of grasslands [8]. However, current land-surface models did not usually differentiate the effects of grazing intensities as well as their combinations with global change factors, which may trigger great challenges for us to predict the C-climate feedbacks in the Anthropocene. Therefore, future land-surface models may need thus to fully consider these processes in order to develop more precise process-based mechanism for forecasting the feedback of grassland ecosystems to climate change.

Fourth, environmental factors (both MAP and MAT) may be crucial in evaluating the response of belowground C and N cycling to different driving factors, as the effects of grazing, global change factors, and their combinations on belowground C and N cycling may change with MAT and MAP transects [6, 14]. The global study also demonstrated that response ratios of soil carbon content and soil nitrogen content to grazing in warmer biomes was clearly higher than those in the low range (**Figure 7**). These results demonstrated the importance of decreasing grazing frequency and intensity in warmer regions than colder ones, which may help to increase soil C sequestration in ecological fragile areas.

#### **Acknowledgements**

This research was financially supported by the "Thousand Young Talents" Program in China, National Natural Science Foundation of China (Grant No. 31600352, 31370489) and "Outstanding doctoral dissertation cultivation plan of action of East China Normal University (Grant No. YB2016023). We would like to acknowledge the permission from Global Change Biology to allow us to transfer our previous part work into monograph chapter to the publics.

**105**

**Author details**

, Lingyan Zhou1

East China Normal University, Shanghai, China

provided the original work is properly cited.

\*Address all correspondence to: xhzhou@des.ecnu.edu.cn

and Xuhui Zhou1,2\*

1 Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem Research, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences,

2 Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Guiyao Zhou1

*Effects of Grazing Intensity on Belowground Carbon and Nitrogen Cycling*

*DOI: http://dx.doi.org/10.5772/intechopen.90416*

#### **Conflict of interest**

All authors declare no conflict of Interests.

*Effects of Grazing Intensity on Belowground Carbon and Nitrogen Cycling DOI: http://dx.doi.org/10.5772/intechopen.90416*

#### **Author details**

*Grasses and Grassland Aspects*

**Acknowledgements**

**Conflict of interest**

Third, grazing intensity (light, moderate, and heavy grazing) significantly affects belowground C and N cycling in grassland ecosystems. Meanwhile, different combinations of grazing and global change factors (e.g., warming, nitrogen addition) also have disparate effects on C and N cycle of grasslands [8]. However, current land-surface models did not usually differentiate the effects of grazing intensities as well as their combinations with global change factors, which may trigger great challenges for us to predict the C-climate feedbacks in the Anthropocene. Therefore, future land-surface models may need thus to fully consider these

processes in order to develop more precise process-based mechanism for forecasting

Fourth, environmental factors (both MAP and MAT) may be crucial in evaluating the response of belowground C and N cycling to different driving factors, as the effects of grazing, global change factors, and their combinations on belowground C and N cycling may change with MAT and MAP transects [6, 14]. The global study also demonstrated that response ratios of soil carbon content and soil nitrogen content to grazing in warmer biomes was clearly higher than those in the low range (**Figure 7**). These results demonstrated the importance of decreasing grazing frequency and intensity in warmer regions than colder ones, which may help to

This research was financially supported by the "Thousand Young Talents" Program in China, National Natural Science Foundation of China (Grant No. 31600352, 31370489) and "Outstanding doctoral dissertation cultivation plan of action of East China Normal University (Grant No. YB2016023). We would like to acknowledge the permission from Global Change Biology to allow us to transfer our

the feedback of grassland ecosystems to climate change.

increase soil C sequestration in ecological fragile areas.

previous part work into monograph chapter to the publics.

All authors declare no conflict of Interests.

**104**

Guiyao Zhou1 , Lingyan Zhou1 and Xuhui Zhou1,2\*

1 Center for Global Change and Ecological Forecasting, Tiantong National Field Station for Forest Ecosystem Research, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China

2 Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China

\*Address all correspondence to: xhzhou@des.ecnu.edu.cn

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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[21] Zhang T, Zhang YJ, Xu MJ, Zhu JT, Wimberly MC, Yu GR, et al. Lightintensity grazing improves alpine meadow productivity and adaption to climate change on the Tibetan plateau. Scientific Reports. 2015;**5**:15949

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[24] Reicosky DC. Tillage-induced CO2 emission from soil. Nutrient Cycling in Agroecosystems. 1997;**49**:273-285

[25] He NP, Zhang YH, Yu Q, Chen SP, Pan QM, Zhang GM, et al. Grazing intensity impacts soil carbon and nitrogen storage of continental steppe.

1995;**50**:294-298

1999;**9**:65-71

*Effects of Grazing Intensity on Belowground Carbon and Nitrogen Cycling DOI: http://dx.doi.org/10.5772/intechopen.90416*

management on the carbon and nitrogen balance of a mixed-grass rangeland. Ecological Applications. 1999;**9**:65-71

[18] Liu N, Zhang YJ, Chang SJ, Kan HM, Lin LJ. Impact of grazing on soil carbon and microbial biomass in typical steppe and desert steppe of Inner Mongolia. PLoS One. 2013;**7**:e36434

[19] Manley J, Schuman G, Reeder JD, Hart RH. Rangeland soil carbon and nitrogen responses to grazing. Journal of Soil and Conservation. 1995;**50**:294-298

[20] Stavi I, Ungar ED, Lavee H, Lavee H, Sarah P. Grazing-induced spatial variability of soil bulk density and content of moisture, organic carbon and calcium carbonate in a semi-arid rangeland. Catena. 2008;**75**:288-296

[21] Zhang T, Zhang YJ, Xu MJ, Zhu JT, Wimberly MC, Yu GR, et al. Lightintensity grazing improves alpine meadow productivity and adaption to climate change on the Tibetan plateau. Scientific Reports. 2015;**5**:15949

[22] Derner J, Briske D, Boutton T. Does grazing mediate soil carbon and nitrogen accumulation beneath C4, perennial grasses along an environmental gradient? Plant and Soil. 1997;**191**:147-156

[23] Baker JM, Ochsner TE, Venterea RT, Griffis TJ. Tillage and soil carbon sequestration—What do we really know? Agriculture, Ecosystems and Environment. 2007;**118**:1-5

[24] Reicosky DC. Tillage-induced CO2 emission from soil. Nutrient Cycling in Agroecosystems. 1997;**49**:273-285

[25] He NP, Zhang YH, Yu Q, Chen SP, Pan QM, Zhang GM, et al. Grazing intensity impacts soil carbon and nitrogen storage of continental steppe. Ecosphere. 2011;**2**:304-316

[26] Parton WJ, Schimel DS, Cole CV, Ojima DS. Analysis of factors controlling soil organic matter levels in Great Plains grasslands. Soil Science Society of America Journal. 1987;**51**:1173-1179

[27] Wu HH, Wiesmeier M, Yu Q, Steffens M, Han XG, Kögel-Knabner I. Labile organic C and N mineralization of soil aggregate size classes in semiarid grasslands as affected by grazing management. Biology and Fertility of Soils. 2012;**48**:305-313

[28] Detling J, Dyer M, Winn D. Net photosynthesis, root respiration, and regrowth of *Bouteloua gracilis* following simulated grazing. Oecologia. 1979;**41**:127-134

[29] Knops JMH, Bradley KL, Wedin DA. Mechanisms of plant species impacts on ecosystem nitrogen cycling. Ecology Letters. 2002;**5**:454-466

[30] Savadogo P, Sawadogo L, Tiveau D. Effects of grazing intensity and prescribed fire on soil physical and hydrological properties and pasture yield in the savanna woodlands of Burkina Faso. Agriculture Ecosystems and Environment. 2007;**118**:80-92

[31] Thomey ML, Collins SL, Vargas R, Johnson JE, Brown RF, Natvig DO, et al. Effect of precipitation variability on net primary production and soil respiration in a Chihuahuan Desert grassland. Global Change Biology. 2011;**17**:1505-1515

[32] Chapin IIFS, Matson PA, Mooney HA. Principles of Terrestrial Ecosystem Ecology. New York, NY, USA: Springer; 2002

[33] Su YZ, Li YL, Cui HY, Zhao WZ. Influences of continuous grazing and livestock exclusion on soil properties in a degraded sandy grassland, Inner Mongolia, northern China. Catena. 2005;**59**:267-278

**106**

*Grasses and Grassland Aspects*

[1] Hufkens K, Keenan TF, Flanagan LB, Scott RL, Bernacchi CJ, Joo E, et al. Productivity of North American grasslands is increased under future climate scenarios despite rising aridity. Nature Climate Change. 2016;**6**:710-716

change. Global Change Biology.

[10] Gong JR, Wang YH, Liu M, Huang YM, Yan X, Zhang ZY, et al. Effects of land use on soil respiration in the temperate steppe of Inner Mongolia,

China. Soil and Tillage Research.

for 61 years after agricultural

[12] Liu N, Kan HM, Yang GW, Zhang YJ. Changes in plant, soil, and microbes in a typical steppe from simulated grazing: Explaining potential change in soil C. Ecological Monographs. 2015;**85**:269-286

[11] Knops JMH, Tilman D. Dynamics of soil nitrogen and carbon accumulation

abandonment. Ecology. 2000;**81**:88-98

[13] Bagchi S, Ritchie ME. Introduced grazers can restrict potential soil carbon sequestration through impacts on plant community composition. Ecology

[14] Mcsherry ME, Ritchie ME. Effects of grazing on grassland soil carbon: A global review. Global Change Biology.

Seagle S. Large mammals and process dynamics in African ecosystems. Bioscience. 1988;**38**:794-800

Mongolian steppe. Biology and Fertility

[17] Schuman GE, Reeder JD, Manley JT, Hart RH, Manley WA. Impact of grazing

[16] Zhou XQ, Wang JZ, Hao YB, Wang YF. Intermediate grazing intensities by sheep increase soil bacterial diversities in an inner

of Soils. 2010;**46**:817-824

Letters. 2010;**13**:959-968

[15] McNaughton S, Ruess R,

2013;**19**:1347-1357

[9] Connell JH. Diversity in tropical rain forests and coral reefs. Science.

2019a;**25**:1119-1132

1978;**199**:1302-1310

2014;**144**:20-31

[2] Follett RF, Reed DA. Soil carbon sequestration in grazing lands: Societal benefits and policy implications. Rangeland Ecology and Management.

[3] Salvati L, Carlucci M. Towards sustainability in agro-forest systems? Grazing intensity, soil degradation and the socioeconomic profile of rural communities in Italy. Ecological

[4] Bai YF, Wu JG, Clark CM, Pan QM, Zhang LX, Chen SP, et al. Grazing alters ecosystem functioning and C:N:P stoichiometry of grasslands along a regional precipitation gradient. Journal of Applied Ecology. 2012;**49**:1204-1215

[5] Zhou GY, Zhou XH, He YH, Shao JJ, Hu ZH, Liu RQ, et al. Grazing intensity significantly affects belowground carbon and nitrogen cycling in grassland ecosystems: A meta-analysis. Global Change Biology. 2017;**23**:1167-1179

[6] Zhou GY, Luo Q, Chen YJ, Hu JQ, He M, Gao J, et al. Interactive effects of grazing and global change factors on soil and ecosystem respiration in grassland ecosystems: A global synthesis. Journal of Applied Ecology. 2019;**56**:2007-2019

[7] Yan L, Zhou GS, Zhang F. Effects of different grazing intensities on grassland production in China: A metaanalysis. PLoS One. 2013;**8**:e81466

[8] Zhou GY, Luo Q, Chen Y, He M, Zhou LY, Frank D, et al. Effects of livestock grazing on grassland carbon storage and release override impacts associated with global climate

Economics. 2015;**112**:1-13

2010;**63**:4-15

**References**

[34] Osem Y, Perevolotsky A, Kigel J. Site productivity and plant size explain the response of annual species to grazing exclusion in a Mediterranean semiarid rangeland. Journal of Ecology. 2004;**92**:297-309

[35] Shi XM, Li XG, Li CT, Zhao Y, Shang ZH, Ma QF. Grazing exclusion decreases soil organic C storage at an alpine grassland of the Qinghai–Tibetan plateau. Ecological Engineering. 2013;**57**:183-187

[36] Xia JY, Niu SL, Wan SQ. Response of ecosystem carbon exchange to warming and nitrogen addition during two hydrologically contrasting growing seasons in a temperate steppe. Global Change Biology. 2009;**15**:1544-1556

[37] Zhou XH, Talley M, Luo YQ. Biomass, litter, and soil respiration along a precipitation gradient in southern Great Plains, USA. Ecosystems. 2009;**12**:1369-1380

[38] Hu ZM, Li SG, Guo Q, Niu SL, He NP, Li LH, et al. A synthesis of the effect of grazing exclusion on carbon dynamics in grasslands in China. Global Change Biology. 2016;**22**:1385-1393

[39] Luyssaert S, Inglima I, Jung M. CO2 balance of boreal, temperate, and tropical forests derived from a global database. Global Change Biology. 2007;**13**:2509-2537

[40] Williams M, Eugster W, Rastetter EB, Mcfadden JP, Chapin FS III. The controls on net ecosystem productivity along an Arctic transect: A model comparison with flux measurements. Global Change Biology. 2000;**6**:116-126

[41] Wang CK, Yang JY, Zhang QZ. Soil respiration in six temperate forests in China. Global Change Biology. 2006;**12**:2103-2114

[42] Holland EA, Detling JK. Plant response to herbivory and belowground nitrogen cycling. Ecology. 1990;**71**:1040-1049

[43] Li CL, Hao XY, Zhao ML, Han GD, Willms WD. Influence of historic sheep grazing on vegetation and soil properties of a desert steppe in Inner Mongolia. Agriculture Ecosystems and Environment. 2008;**128**:109-116

[44] Lu M, Zhou XH, Luo YQ, Yang YH, Fang CM, Chen JK, et al. Minor stimulation of soil carbon storage by nitrogen addition: A metaanalysis. Agriculture Ecosystems and Environment. 2011;**140**:234-244

[45] Zhou LY, Zhou XH, Zhang BC, Lu M, Luo YQ, Liu LL, et al. Different responses of soil respiration and its components to nitrogen addition among biomes: A meta-analysis. Global Change Biology. 2014;**20**:2332-2343

**109**

**Chapter 6**

**Abstract**

*and Xue-Feng Ma*

United States, wheat

**1. Introduction**

Small Grains as Winter Pasture

in the Southern Great Plains

*Tadele T. Kumssa, Joshua D. Anderson, Twain J. Butler* 

**Keywords:** forage, oat, rye, small grains, Southern Great Plains, triticale,

Small grains, such as wheat (*Triticum aestivum* L.), rye (*Secale cereale* L.), triticale (*X Triticosecale* Wittmack), and oat (*Avena sativa* L.), are an integral part of the forage-livestock system in the Southern Great Plains (SGP) of the United States, as they can be grazed during cool-season months when other forage species are not productive. On average in the last 3 years (2016–2018), 7 million hectares of land was planted annually by wheat alone for forage and grain production in the SGP, including Kansas, Oklahoma, and Texas [1], which is the largest area of low-rainfall winter wheat cropland worldwide. The SGP (32–40°N; 96–104°W) is generally classified as grassland, cropland, and forest land [2]. Although many crop species grow in the area, winter wheat covers the largest amount of cropland in the region. Small grains are well adapted to the SGP's environment, for both forage and grain (i.e., dual

Small-grain cereals are widely adapted and used as annual cool-season pastures in the Southern Great Plains (SGP) of the United States, where livestock and forage production are the largest contributors to agricultural income. The advantage of growing small grains in the region is evident due to the widespread adoption and flexibility of production for grain only, forage only, or both grain and forage (i.e., dual purpose). Farmers in the SGP often prefer the use of small grains for dual purpose mainly because of alternative income options from livestock and/or grain, ensuring stable income especially when product prices fluctuate with market demands. Small-grain forage is exceptionally important during autumn, winter, and early spring when forage availability from other sources is low. By providing nutritionally high-quality forage, small grains minimize the need for protein and energy supplements. Besides being used for winter pasture, small grains also serve as cool-season cover crops. While small grains offer different advantages in the integrated crop-livestock system in the region, farming management practices can play an important role to maximize the benefit. The objectives of this chapter are to summarize the significance of small grains as winter pasture and highlight the production status of each small-grain species in the SGP of the United States.

of the United States

#### **Chapter 6**

*Grasses and Grassland Aspects*

2004;**92**:297-309

2013;**57**:183-187

[34] Osem Y, Perevolotsky A, Kigel J. Site productivity and plant size explain the response of annual species to grazing exclusion in a Mediterranean semiarid rangeland. Journal of Ecology.

nitrogen cycling. Ecology. 1990;**71**:1040-1049

[44] Lu M, Zhou XH, Luo YQ, Yang YH, Fang CM, Chen JK, et al. Minor stimulation of soil carbon storage by nitrogen addition: A metaanalysis. Agriculture Ecosystems and Environment. 2011;**140**:234-244

[45] Zhou LY, Zhou XH, Zhang BC, Lu M, Luo YQ, Liu LL, et al. Different responses of soil respiration and its components to nitrogen addition among biomes: A meta-analysis. Global Change

Biology. 2014;**20**:2332-2343

[43] Li CL, Hao XY, Zhao ML, Han GD, Willms WD. Influence of historic sheep grazing on vegetation and soil properties of a desert steppe in Inner Mongolia. Agriculture Ecosystems and Environment. 2008;**128**:109-116

[35] Shi XM, Li XG, Li CT, Zhao Y, Shang ZH, Ma QF. Grazing exclusion decreases soil organic C storage at an alpine grassland of the Qinghai–Tibetan

plateau. Ecological Engineering.

[37] Zhou XH, Talley M, Luo YQ. Biomass, litter, and soil respiration along a precipitation gradient in southern Great Plains,

USA. Ecosystems. 2009;**12**:1369-1380

[39] Luyssaert S, Inglima I, Jung M. CO2 balance of boreal, temperate, and tropical forests derived from a global database. Global Change Biology.

measurements. Global Change Biology.

[41] Wang CK, Yang JY, Zhang QZ. Soil respiration in six temperate forests in China. Global Change Biology.

[42] Holland EA, Detling JK. Plant response to herbivory and belowground

2007;**13**:2509-2537

2000;**6**:116-126

2006;**12**:2103-2114

[40] Williams M, Eugster W, Rastetter EB, Mcfadden JP, Chapin FS III. The controls on net ecosystem productivity along an Arctic transect: A model comparison with flux

[38] Hu ZM, Li SG, Guo Q, Niu SL, He NP, Li LH, et al. A synthesis of the effect of grazing exclusion on carbon dynamics in grasslands in China. Global Change Biology. 2016;**22**:1385-1393

[36] Xia JY, Niu SL, Wan SQ. Response of ecosystem carbon exchange to warming and nitrogen addition during two hydrologically contrasting growing seasons in a temperate steppe. Global Change Biology. 2009;**15**:1544-1556

**108**
