overgrazing

{{Further|Land degradation}}

Overgrazing typically increases soil erosion.C. Michael Hogan (2009). "[http://www.eoearth.org/article/Overgrazing Overgrazing]" ({{Webarchive|url=https://web.archive.org/web/20100711111015/http://www.eoearth.org/article/Overgrazing |date=2010-07-11 }}). Encyclopedia of Earth. Sidney Draggan, topic ed.; Cutler J. Cleveland, ed. Washington, D.C.: National Council for Science and the Environment.

With continued overutilization of land for grazing, there is an increase in degradation. This leads to poor soil conditions that only xeric and early successional species can tolerate.{{cite journal |last1=Fuls |first1=E.R. |title=Ecosystem modification created by patch-overgrazing in semi-arid grassland |journal=Journal of Arid Environments |date=1992 |volume=23 |issue=1 |pages=59–69 |bibcode=1992JArEn..23...59F |doi=10.1016/S0140-1963(18)30541-X}} A meta-analysis of 148 studies found that the value of most ecosystem functions declines with increasing grazing intensity and that increasing aridity weakens positive impacts of light grazing.{{Cite journal |last1=Niu |first1=Weiling |last2=Ding |first2=Jingyi |last3=Fu |first3=Bojie |last4=Zhao |first4=Wenwu |last5=Eldridge |first5=David |date=2025-02-01 |title=Global effects of livestock grazing on ecosystem functions vary with grazing management and environment |url=https://www.sciencedirect.com/science/article/abs/pii/S0167880924004146 |journal=Agriculture, Ecosystems & Environment |volume=378 |pages=109296 |doi=10.1016/j.agee.2024.109296 |bibcode=2025AgEE..37809296N |issn=0167-8809}}

Native plant grass species, both individual bunch grasses and in grasslands, are especially vulnerable. For example, excessive browsing by white-tailed deer can lead to the growth of less preferred species of grasses and ferns or non-native plant speciesCôté, S. D., Rooney, T. P., Tremblay, J. P., Dussault, C., & Waller, D. M. (2004). "Ecological impacts of deer overabundance". Annu. Rev. Ecol. Evol. Syst., 35, 113-147. that can potentially displace native, woody plants, decreasing the biodiversity.Baiser, B., Lockwood, J. L., La Puma, D., & Aronson, M. F. (2008). "A perfect storm: two ecosystem engineers interact to degrade deciduous forests of New Jersey". Biological Invasions, 10(6), 785-795.Horsley, S. B., Stout, S. L., & DeCalesta, D. S. (2003). White‐tailed deer impact on the vegetation dynamics of a northern hardwood forest. Ecological applications, 13(1), 98-118.

Turning to the aquatic environment, Ling et al. (2015){{Cite journal |last1=Ling |first1=S. D. |last2=Scheibling |first2=R. E. |last3=Rassweiler |first3=A. |last4=Johnson |first4=C. R. |last5=Shears |first5=N. |last6=Connell |first6=S. D. |last7=Salomon |first7=A. K. |last8=Norderhaug |first8=K. M. |last9=Pérez-Matus |first9=A. |last10=Hernández |first10=J. C. |last11=Clemente |first11=S. |last12=Blamey |first12=L. K. |last13=Hereu |first13=B. |last14=Ballesteros |first14=E. |last15=Sala |first15=E. |date=2015-01-05 |title=Global regime shift dynamics of catastrophic sea urchin overgrazing |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |language=en |volume=370 |issue=1659 |pages=20130269 |doi=10.1098/rstb.2013.0269 |issn=0962-8436 |pmc=4247405}} have documented the phenomenon of catastrophic sea urchin overgrazing and its role in marine ecosystem regime shifts. Their study underscores the urgent need for effective management and conservation strategies to mitigate the profound ecological impacts of overgrazing, highlighting the issue's global scope. Similarly, on the Mongolian steppes, Liu et al. (2013){{Cite journal |last1=Liu |first1=Yi Y. |last2=Evans |first2=Jason P. |last3=McCabe |first3=Matthew F. |last4=Jeu |first4=Richard A. M. de |last5=Dijk |first5=Albert I. J. M. van |last6=Dolman |first6=Albertus J. |last7=Saizen |first7=Izuru |date=2013-02-25 |title=Changing Climate and Overgrazing Are Decimating Mongolian Steppes |journal=PLOS ONE |language=en |volume=8 |issue=2 |pages=e57599 |doi=10.1371/journal.pone.0057599 |doi-access=free |issn=1932-6203 |pmc=3581472 |pmid=23451249|bibcode=2013PLoSO...857599L }} found that approximately 60% of vegetation decline could be attributed to climate factors, with the rest significantly influenced by increased goat density due to overgrazing. This points to a complex interplay between climate change and grazing practices in ecosystem degradation.

Further expanding our understanding, Stevens et al. (2016){{Cite journal |last1=Stevens |first1=Nicola |last2=Erasmus |first2=B. F. N. |last3=Archibald |first3=S. |last4=Bond |first4=W. J. |date=2016-09-19 |title=Woody encroachment over 70 years in South African savannahs: overgrazing, global change or extinction aftershock? |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |language=en |volume=371 |issue=1703 |pages=20150437 |doi=10.1098/rstb.2015.0437 |issn=0962-8436 |pmc=4978877 |pmid=27502384}} investigated woody encroachment in South African savannahs over a 70-year period, identifying overgrazing, global changes, and the ecological effects of megafauna extinction as key factors. Their findings shed light on the multifaceted drivers behind changes in savannah ecosystems. Echoing this theme of alternative strategies to combat overgrazing, Kriegisch et al. (2019){{Cite journal |last1=Kriegisch |first1=N. |last2=Reeves |first2=S. E. |last3=Flukes |first3=E. B. |last4=Johnson |first4=C. R. |last5=Ling |first5=S. D. |date=2019-07-01 |title=Drift-kelp suppresses foraging movement of overgrazing sea urchins |url=https://doi.org/10.1007/s00442-019-04445-6 |journal=Oecologia |language=en |volume=190 |issue=3 |pages=665–677 |doi=10.1007/s00442-019-04445-6 |pmid=31250188 |bibcode=2019Oecol.190..665K |issn=1432-1939}} demonstrated how drift-kelp availability could reduce the foraging movement of overgrazing sea urchins, suggesting that alternative food sources may significantly influence grazing behaviors and aid in managing marine ecosystem pressures.

In a similar vein, the research by Cai et al. (2020){{Cite journal |last1=Cai |first1=Yurong |last2=Yan |first2=Yuchun |last3=Xu |first3=Dawei |last4=Xu |first4=Xingliang |last5=Wang |first5=Chu |last6=Wang |first6=Xu |last7=Chen |first7=Jinqiang |last8=Xin |first8=Xiaoping |last9=Eldridge |first9=David J. |date=2020-03-01 |title=The fertile island effect collapses under extreme overgrazing: evidence from a shrub-encroached grassland |url=https://doi.org/10.1007/s11104-020-04426-2 |journal=Plant and Soil |language=en |volume=448 |issue=1 |pages=201–212 |doi=10.1007/s11104-020-04426-2 |bibcode=2020PlSoi.448..201C |issn=1573-5036}} presents a stark example of the terrestrial impact of overgrazing, showing how the fertile island effect collapses under extreme conditions in shrub-encroached grasslands. This case study emphasizes the critical need for sustainable grazing practices to protect soil health and maintain ecosystem functionality, further illustrating the wide-reaching consequences of overgrazing across diverse habitats.

{{Main|Common land}}

Overgrazing is used as an

example in the economic concept now known as the Tragedy of the Commons devised in a 1968 paper by Garrett Hardin.Garrett Hardin (December 13, 1968), [https://www.science.org/doi/10.1126/science.162.3859.1243 "The Tragedy of the Commons"], Science, Vol. 162, No. 3859, pp. 1243-1248. Also available [http://www.sciencemag.org/cgi/reprint/162/3859/1243.pdf here] and [http://www.garretthardinsociety.org/articles/art_tragedy_of_the_commons.html here]. This cited the work of a Victorian economist who used as an example the over-grazing of common land. Hardin's example could only apply to unregulated use of land regarded as a common resource.

Normally, rights of use of common land in England and Wales were, and still are, closely regulated, and available only to "commoners". If excessive use was made of common land, for example in overgrazing, a common would be "stinted", that is, a limit would be put on the number of animals each commoner was allowed to graze. These regulations were responsive to demographic and economic pressure; thus rather than let a common become degraded, access was restricted even further. This important part of actual historic practice was absent from the economic model of Hardin.Susan Jane Buck Cox (Spring 1985). [http://dlc.dlib.indiana.edu/dlc/bitstream/handle/10535/3113/buck_NoTragedy.pdf?sequence=1&isAllowed=y "No Tragedy on the Commons"]. Journal of Environmental Ethics, Vol. 7. In reality the use of common land in England and Wales was a triumph of conserving a scarce resource using agreed custom and practice.

There have been overgrazing consequences in the region Sahel region. The violent herder–farmer conflicts in Nigeria, Mali, Sudan and other countries in the Sahel region have been exacerbated by land degradation and overgrazing.{{cite news |title=The Deadliest Conflict You've Never Heard of |url=https://www.foreignaffairs.com/articles/nigeria/2019-01-23/deadliest-conflict-youve-never-heard |work=Foreign Policy |date=23 January 2019}}{{cite news |title=The battle on the frontline of climate change in Mali |url=https://www.bbc.com/news/the-reporters-46921487 |work=BBC News |date=22 January 2019}} See 2010 Sahel famine.

Various countries in Sub-Sahara Africa are affected by overgrazing and resulting ecological effects.

In Namibia, overgrazing is considered the main cause of woody plant encroachment at the expenses of grasses on a land area of up to 45 million hectares.

In many arid zones in Australia, overgrazing by sheep and cattle during the 19th century, as pastoralism was introduced by European settlers, caused many long-lived species of trees and shrubs to give way to short-lived annual plants and weed species. Introduced feral rabbits, cats and foxes exacerbated the threat to both flora and fauna. Many bird species have become extinct or endangered, and many of the medium-sized desert mammals are now completely extinct or only exist on a few islands of Australia.{{cite web | title=Arid Recovery – Roxby Downs, South Australia | website=EMR Project Summaries | date=15 March 2016 | url=https://site.emrprojectsummaries.org/2016/03/15/arid-recovery-roxby-downs-south-australia/ | access-date=27 October 2020}}

Overgrazing can also occur with native species. In the Australian Capital Territory, the local government in 2013 authorised a cull of 1455 kangaroos due to overgrazing.{{Cite web|date=2013-07-10|title=ACT Territory and Municipal Services Directorate {{!}} Media Releases Kangaroo conservation cull to go ahead|url=https://www.cmtedd.act.gov.au/open_government/inform/act_government_media_releases/tamsd/2013/july/kangaroo-conservation-cull-to-go-ahead|url-status=live|archive-url=https://webarchive.nla.gov.au/awa/20200702004610/http://pandora.nla.gov.au/pan/144647/20200702-0411/www.cmtedd.act.gov.au/open_government/inform/act_government_media_releases/tamsd/2013/july/kangaroo-conservation-cull-to-go-ahead.html|archive-date=2020-07-02|access-date=2021-06-12|website=ACT Territory and Municipal Services Directorate|publisher=Government of the Australian Capital Territory}}{{cbignore|bot=medic}} Maisie Carr (1912-1988), Ecologist and Botanist, undertook significant research and studies in overgrazing and established consequences on the surrounding land in Australia.

In the Caribbean region, overgrazing is a threat to vegetation areas where there is livestock farming, which is an important source of livelihood and food security for many people. a combination of small scale livestock farming with small ruminants, and mixed farming is practised. However, livestock consume vegetation faster than it can be renewed and this leads to land degradation, loss of vegetative areas, and soil erosion resulting in poor quality feed and reduced livestock yields and income. Also, these grazing lands are critical in controlling carbon dioxide and mitigating risks against severe weather such as floods and droughts. Overgrazing weakens ecological conservation.{{Cite web |title=Caribbean Islands - Threats {{!}} CEPF |url=https://www.cepf.net/our-work/biodiversity-hotspots/caribbean-islands/threats |access-date=2024-04-08 |website=www.cepf.net |language=en}}

In New Zealand, overgrazing is a massive threat to the native species of flora and fauna, especially the native bushes which are often overlooked by invasive species looking for homes.{{fact|date=May 2024}} Mustalids, rabbits, hares and possums often eat the plants that hold soil together. This makes the ground very unstable and crumbly. If soil is unstable, it is prone to collapse in extreme weather events such as floods and heavy rain. This is detrimental to farmers of crops and animals alike. 40% of the native species of New Zealand have been wiped out by pests including humans.{{fact|date=May 2024}}

• Land degradation
• Desertification

{{Reflist}}

• {{cite book|last=Gonner|first=E. C. K|title=Common Land and Inclosure|url=https://archive.org/details/in.ernet.dli.2015.223567|place=London|publisher=Macmillan & Co|year=1912}} [https://archive.org/details/cu31924079597336]

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Category:Land use

Category:Land management

Category:Livestock

Category:Sustainable agriculture

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Category:Grasslands

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