Editing Acorn (section)

==Ecology==

[[File:Ponies eating acorns on Parkhill Lawn, New Forest - geograph.org.uk - 251840.jpg|thumb|[[Ponies]] eating acorns.  Acorns can cause painful death in [[equines]], especially if eaten in excess.]]

[[File:Quercus robur - sprouting acorn.jpg|thumb|Sprouting acorn of ''[[Quercus robur]]'']]

Acorns play an important role in [[forest ecology]] when oaks are plentiful or dominant in the landscape.<ref name="USDA">{{Cite book |url=http://www.fs.fed.us/psw/publications/documents/psw_gtr044/psw_gtr044.pdf |title=Proceedings of the symposium on the ecology, management, and utilization of California oaks, June 26–28 |publisher=USDA Forest Service General Technical Report PSW-044 |year=1980 |editor-last=Plumb, Timothy R. |pages=1 to 368 |asin=B000PMY1P8}}</ref> The volume of the acorn crop may vary widely, creating great abundance or great stress on the many animals dependent on acorns and the predators of those animals.<ref name="NYT">{{Cite news |last=King, Richie S. |date=2 December 2011 |title=After Lean Acorn Crop in Northeast, Even People May Feel the Effects |work=The New York Times |url=https://www.nytimes.com/2011/12/03/nyregion/boom-and-bust-in-acorns-will-affect-many-creatures-including-humans.html |access-date=4 December 2011 |quote=there is nothing unusual about large fluctuations in the annual number of acorns.}}</ref> Acorns, along with other nuts, are termed [[mast (botany)|mast]].

Wildlife that consume acorns as an important part of their diets include birds, such as [[jay]]s, [[pigeon]]s, some [[duck]]s, and several species of [[woodpecker]]s. Small [[mammal]]s that feed on acorns include [[mouse|mice]], [[squirrel]]s and several other [[rodent]]s. One beetle species, ''[[Thorectes lusitanicus]]'', also feeds on acorns.<ref>{{Cite journal |last1=PéRez-Ramos |first1=Ignacio M. |last2=MarañóN |first2=Teodoro |last3=Lobo |first3=Jorge M. |last4=Verdú |first4=José R. |date=August 2007 |title=Acorn removal and dispersal by the dung beetle Thorectes lusitanicus : ecological implications |url=https://resjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-2311.2007.00874.x |journal=Ecological Entomology |language=en |volume=32 |issue=4 |pages=349–356 |doi=10.1111/j.1365-2311.2007.00874.x |bibcode=2007EcoEn..32..349P |issn=0307-6946|hdl=10261/47760 |hdl-access=free }}</ref> Acorns have a large influence on small [[rodent]]s in their [[habitat]]s, as large acorn yields help rodent populations to grow.<ref>{{Cite web |title=Acorn Study {{!}} Research {{!}} Upland Hardwood Ecology and Management {{!}} SRS |url=https://www.srs.fs.usda.gov/uplandhardwood/research/article/acorn-study |access-date=2020-09-04 |website=srs.fs.usda.gov}}</ref>

Large mammals such as pigs, bears, and [[deer]] also consume large amounts of acorns; they may constitute up to 25% of the diet of deer in the autumn.<ref>{{Cite book |last=Barrett, Reginald H. |title=Proceedings of the symposium on the ecology, management, and utilization of California oaks, June 26–28 |publisher=USDA Forest Service General Technical Report PSW-044 |year=1980 |editor-last=Plumb, Timothy R. |pages=276–291 |chapter=Mammals of California Oak Habitats-Management Implications |chapter-url=http://www.fs.fed.us/psw/publications/documents/psw_gtr044/psw_gtr044.pdf}}</ref> In Spain, Portugal and the [[New Forest]] region of southern England, pigs are still turned loose in ''[[Dehesa (pastoral management)|dehesas]]'' (large oak [[grove (nature)|grove]]s) in the autumn, to fill and fatten themselves on acorns. Heavy consumption of acorns can, on the other hand, be toxic to other animals that cannot detoxify their [[tannin]]s, such as horses and cattle,<ref>{{Cite web |date=19 October 2011 |title=A bumper crop of acorns causes concern for those with horses |url=http://www.countryfile.com/news/bumper-crop-acorns-causes-concern-those-horses |access-date=27 January 2014 |website=Countryfile.com |publisher=Immediate Media Company}}</ref><ref name="Barringer">{{Cite web |last=Barringer |first=Sam |title=Acorns Can be Deadly |url=http://www.caf.wvu.edu/~forage/acorns/acorns.htm |url-status=dead |archive-url=https://web.archive.org/web/20140227141549/http://www.caf.wvu.edu/~forage/acorns/acorns.htm |archive-date=27 February 2014 |access-date=27 January 2014 |website=West Virginia University Extension Service}}</ref> especially if eaten in excess.<ref>{{Cite web |date=2013-11-27 |title=Acorns fatally poison 50 ponies in English forest |url=http://horsetalk.co.nz/2013/11/23/acorns-fatally-poison-50-ponies-english-forest/#axzz40efTYqgN |access-date=2017-01-06 |publisher=Horsetalk.co.nz}}</ref><ref>{{Cite web |title=Acorn Poisoning – Are Acorns Poisonous To Horses? |url=http://www.horse-advice.com/equestrian/equine-veterinary/acorns-poisonous.shtml |access-date=2017-01-06 |publisher=Horse-advice.com}}</ref><ref>{{Cite web |date=2002-09-15 |title=Acorns, Oaks and Horses: Tannin Poisoning |url=http://www.thewayofhorses.com/10_08_acorns.html |access-date=2017-01-06 |publisher=The Way of Horses}}</ref>

The [[larva]]e of some [[moth]]s and [[weevil]]s also live in young acorns, consuming the kernels as they develop.<ref>Brown, Leland R. (1979) ''Insects Feeding on California Oak Trees''in ''Proceedings of the Symposium on Multiple-Use Management of California's Hardwood Resources'', Timothy Plum and Norman Pillsbury (eds.).</ref>

Acorns are attractive to animals because they are large and thus efficiently consumed or cached. Acorns are also rich in nutrients. Percentages vary from species to species, but all acorns contain large amounts of [[protein]], [[carbohydrate]]s and [[fat]]s, as well as the minerals [[calcium]], [[phosphorus]] and [[potassium]], and the [[vitamin]] [[Niacin (nutrient)|niacin]]. Total [[food energy]] in an acorn also varies by species, but all compare well with other wild foods and with other nuts.<ref>{{Cite web |title=Nutrition Facts for Acorn Flour |url=http://www.nutritiondata.com/facts-001-02s02dn.html |access-date=2017-01-06 |publisher=Nutritiondata.com}}</ref>

Acorns also contain bitter [[tannin]]s, the amount varying with the species. Since tannins, which are plant [[polyphenol]]s, interfere with an animal's ability to [[metabolize]] protein, creatures must adapt in different ways to use the nutritional value acorns contain. Animals may preferentially select acorns that contain fewer tannins. When the tannins are metabolized in cattle, the tannic acid produced can cause [[ulceration]] and [[kidney]] failure.<ref name="Barringer" />

Animals that [[cache (biology)|cache]] acorns, such as jays and squirrels, may wait to consume some of these acorns until sufficient groundwater has [[percolate]]d through them to [[Leaching (chemical science)|leach]] out the tannins. Other animals buffer their acorn diet with other foods. Many insects, birds, and mammals metabolize tannins with fewer ill effects than do humans.

Species of acorn that contain large amounts of tannins are very bitter, [[astringent]], and potentially irritating if eaten raw. This is particularly true of the acorns of American [[Quercus rubra|red oaks]] and [[Pedunculate oak|English oaks]]. The acorns of [[white oak]]s, being much lower in tannins, are nutty in flavor; this characteristic is enhanced if the acorns are given a light roast before grinding.

Tannins can be removed by soaking chopped acorns in several changes of water, until the water no longer turns brown. Cold water leaching can take several days, but three to four changes of boiling water can leach the tannins in under an hour.<ref>{{Cite book |last=Tull |first=Delena |title=A practical guide to edible & useful plants : including recipes, harmful plants, natural dyes & textile fibers |date=1987 |publisher=Texas Monthly Press |isbn=9780877190226 |location=Austin, Tex. |oclc=15015652}}</ref> Hot water leaching (boiling) cooks the starch of the acorn, which would otherwise act like gluten in flour, helping it bind to itself. For this reason, if the acorns will be used to make flour, then cold water leaching is preferred.<ref>{{Cite news |title=Two Ways to Make Cold Leached Acorn Flour – Learn How with this Guide |work=The Spruce |url=https://www.thespruce.com/cold-leaching-and-preserving-acorn-flour-4007438 |access-date=2017-12-24 |archive-date=25 December 2017 |archive-url=https://web.archive.org/web/20171225035849/https://www.thespruce.com/cold-leaching-and-preserving-acorn-flour-4007438 |url-status=dead }}</ref>

Being rich in fat, acorn flour can spoil or [[Mold (fungus)|mold]]er easily and must be carefully stored. Acorns are also sometimes prepared as a massage oil.

Acorns of the white oak group, ''Leucobalanus'', typically start rooting as soon as they are in contact with the soil (in the fall), then send up the leaf shoot in the spring.

===Dispersal agents===

Acorns are too heavy for [[wind dispersal]], so they require other ways to spread. Oaks therefore depend on [[Biological dispersal|biological seed dispersal]] agents to move the acorns beyond the mother tree and into a suitable area for germination (including access to adequate water, sunlight and soil nutrients), ideally a minimum of {{convert|20–30|m|ft|-1|abbr=on}} from the parent tree.{{Citation needed|date=January 2010}}

Many animals eat unripe acorns on the tree or ripe acorns from the ground, with no reproductive benefit to the oak, but some animals, such as [[squirrel]]s and [[jay]]s serve as seed dispersal agents. Jays and squirrels that scatter-hoard acorns in caches for future use effectively plant acorns in a variety of locations in which it is possible for them to germinate and thrive.

Even though jays and squirrels retain remarkably large mental maps of cache locations and return to consume them, the odd acorn may be lost, or a jay or squirrel may die before consuming all of its stores. A small number of acorns manage to germinate and survive, producing the next generation of oaks.

Scatter-hoarding behavior depends on jays and squirrels associating with plants that provide good packets of food that are nutritionally valuable, but not too big for the dispersal agent to handle. The beak sizes of jays determine how large acorns may get before jays ignore them.

Acorns germinate on different schedules, depending on their place in the oak family. Once acorns sprout, they are less nutritious, as the seed tissue converts to the indigestible [[lignin]]s that form the root.<ref>{{Citation |last=Janzen |first=Daniel H. |title=Seed Predation by Animals |journal=Annual Review of Ecology and Systematics |volume=2 |pages=465–492 |year=1971 |issue=1 |editor-last=Richard F. Johnson, Peter W. Frank and Charles Michner |doi=10.1146/annurev.es.02.110171.002341 |jstor=2096937|bibcode=1971AnRES...2..465J }}</ref>

{{nutritionalvalue
| name=Acorn, raw
| water=27.9 g
| kJ=1619
| protein=6.15 g
| fat=23.85 g
| satfat=3.102 g
| monofat = 15.109 g
| polyfat = 4.596 g
| carbs=40.75 g
| calcium_mg=41
| copper_mg = .621
| iron_mg=0.79
| magnesium_mg=62
| phosphorus_mg=79
| potassium_mg=539
| sodium_mg=0
| manganese_mg=1.337
| zinc_mg=0.51
| vitC_mg=0.0
| thiamin_mg=0.112
| riboflavin_mg=0.118
| niacin_mg=1.827
| pantothenic_mg=0.715
| vitB6_mg=0.528
| folate_ug=87
| vitA_ug=2
<!-- amino acids -->
| tryptophan=0.074 g
| threonine=0.236 g
| isoleucine=0.285 g
| leucine=0.489 g
| lysine=0.384 g
| methionine=0.103 g
| cystine=0.109 g
| phenylalanine=0.269 g
| tyrosine=0.187 g
| valine=0.345 g
| arginine=0.473 g
| histidine=0.170 g
| alanine=0.350 g
| aspartic acid=0.635 g
| glutamic acid=0.986 g
| glycine=0.285 g
| proline=0.246 g
| serine=0.261 g
| source_usda=1
| note=[https://fdc.nal.usda.gov/fdc-app.html#/food-details/170157/nutrients Link to USDA Database entry]
}}