Editing Reforestation (section)

== Challenges ==
{{See also|Tree plantations#Problems}}
There is often insufficient integration between the different purposes of reforestation, namely economic utilization, enhancement of biodiversity and carbon sequestration.<ref>{{Cite journal |last1=Martin |first1=Meredith P. |last2=Woodbury |first2=David J. |last3=Doroski |first3=Danica A. |last4=Nagele |first4=Eliot |last5=Storace |first5=Michael |last6=Cook-Patton |first6=Susan C. |last7=Pasternack |first7=Rachel |last8=Ashton |first8=Mark S. |date=2021-09-01 |title=People plant trees for utility more often than for biodiversity or carbon |journal=Biological Conservation |volume=261 |pages=109224 |doi=10.1016/j.biocon.2021.109224 |issn=0006-3207|doi-access=free |bibcode=2021BCons.26109224M }}</ref> This can lead to a range of different challenges.

=== Competition with other land uses and displacement risk ===
Reforestation can compete with other land uses, such as food production, livestock grazing, and living space, for further economic growth.<ref>{{Cite journal |last1=Smith |first1=Pete |last2=Gregory |first2=Peter J. |last3=van Vuuren |first3=Detlef |last4=Obersteiner |first4=Michael |last5=Havlík |first5=Petr |last6=Rounsevell |first6=Mark |last7=Woods |first7=Jeremy |last8=Stehfest |first8=Elke |last9=Bellarby |first9=Jessica |date=2010-09-27 |title=Competition for land |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |volume=365 |issue=1554 |pages=2941–2957 |doi=10.1098/rstb.2010.0127 |pmc=2935113 |pmid=20713395}}</ref><ref name="Cunningham 301–317">{{Cite journal |last1=Cunningham |first1=S. C. |last2=Mac Nally |first2=R. |last3=Baker |first3=P. J. |last4=Cavagnaro |first4=T. R. |last5=Beringer |first5=J. |last6=Thomson |first6=J. R. |last7=Thompson |first7=R. M. |date=2015-07-01 |title=Balancing the environmental benefits of reforestation in agricultural regions |journal=Perspectives in Plant Ecology, Evolution and Systematics |language=en |volume=17 |issue=4 |pages=301–317 |doi=10.1016/j.ppees.2015.06.001 |issn=1433-8319|doi-access=free |bibcode=2015PPEES..17..301C |hdl=2440/95479 |hdl-access=free }}</ref> Reforestation can also divert large amounts of water from other activities.<ref>{{Cite journal |last=Belluscio |first=Ana |date=2009-11-07 |title=Planting trees can shift water flow |url=https://www.nature.com/articles/news.2009.1057 |journal=Nature |language=en |doi=10.1038/news.2009.1057 |issn=1476-4687}}</ref> A map created by the [[World Resources Institute]] in collaboration with the [[International Union for Conservation of Nature|IUCN]] identifies 2 billion hectares for potential forest restoration and is criticized for including 900 million hectares of grasslands.<ref>{{Cite journal|last1=Bond|first1=William J.|last2=Stevens|first2=Nicola|last3=Midgley|first3=Guy F.|last4=Lehmann|first4=Caroline E.R.|date=November 2019|title=The Trouble with Trees: Afforestation Plans for Africa|url=https://linkinghub.elsevier.com/retrieve/pii/S0169534719302526|journal=Trends in Ecology & Evolution|language=en|volume=34|issue=11|pages=963–965|doi=10.1016/j.tree.2019.08.003|pmid=31515117|bibcode=2019TEcoE..34..963B |hdl=20.500.11820/ad569ac5-dc12-4420-9517-d8f310ede95e|s2cid=202568025|hdl-access=free}}</ref><ref>{{Cite web|last=Dasgupta|first=Shreya|date=2021-06-01|title=Many Tree-Planting Campaigns Are Based on Flawed Science|url=https://science.thewire.in/environment/many-tree-planting-campaigns-are-based-on-flawed-science/|access-date=2021-06-12|website=The Wire Science|language=en-GB}}</ref> An assessment of the pledges of governments for reforestation found that the sum of global pledges translates to a required land area of 1.2bn hectares, until 2060, which is equal to a tenth of the global land area und thus deemed unrealistic without a significant encroachment on non-forest areas.<ref name=":5">{{Cite web |last=Financial Times |date=2023-09-21 |title=The illusion of saving the planet with a trillion trees |url=https://ig.ft.com/one-trillion-trees/ |access-date=2023-10-21 |website=subs.ft.com |language=en-gb}}</ref> Experts are calling for a better integration of social data, such as the dependence of livelihoods on specific land uses, into restoration efforts.<ref>{{Cite journal |last1=Schultz |first1=Bill |last2=Brockington |first2=Dan |last3=Coleman |first3=Eric A |last4=Djenontin |first4=Ida |last5=Fischer |first5=Harry W |last6=Fleischman |first6=Forrest |last7=Kashwan |first7=Prakash |last8=Marquardt |first8=Kristina |last9=Pfeifer |first9=Marion |last10=Pritchard |first10=Rose |last11=Ramprasad |first11=Vijay |date=2022-11-01 |title=Recognizing the equity implications of restoration priority maps |journal=Environmental Research Letters |volume=17 |issue=11 |pages=114019 |doi=10.1088/1748-9326/ac9918 |bibcode=2022ERL....17k4019S |s2cid=253157136 |issn=1748-9326|doi-access=free }}</ref> Possible solutions include the integration of other land uses into forests through [[agroforestry]], such as growing coffee plants under trees, reducing the delineation between forests and other land uses.<ref name=":5" />

A study found that almost 300 million people live on tropical forest restoration opportunity land in the [[Global South]], constituting a large share of low-income countries' populations, and argues for prioritized inclusion of "local communities" in forest restoration projects.<ref>{{cite news |title=Global forest restoration and the importance of empowering local communities |url=https://phys.org/news/2020-08-global-forest-importance-empowering-local.html |access-date=5 September 2020 |work=phys.org |language=en}}</ref><ref>{{cite news |date=25 August 2020 |title=300 million world over can have their forests restored: study |url=https://www.thehindu.com/news/cities/Hyderabad/300-million-world-over-can-have-their-forests-restored-study/article32440958.ece |access-date=5 September 2020 |work=The Hindu |language=en-IN}}</ref><ref>{{cite journal |last1=Erbaugh |first1=J. T. |last2=Pradhan |first2=N. |last3=Adams |first3=J. |last4=Oldekop |first4=J. A. |last5=Agrawal |first5=A. |last6=Brockington |first6=D. |last7=Pritchard |first7=R. |last8=Chhatre |first8=A. |date=24 August 2020 |title=Global forest restoration and the importance of prioritizing local communities |url=https://www.nature.com/articles/s41559-020-01282-2 |journal=Nature Ecology & Evolution |language=en |volume=4 |issue=11 |pages=1472–1476 |bibcode=2020NatEE...4.1472E |doi=10.1038/s41559-020-01282-2 |issn=2397-334X |pmid=32839542 |s2cid=221285189 |access-date=5 September 2020}}</ref>

There are calls for a more selective approach to identifying reforestation areas, taking into account the possible displacement of customary land uses.<ref>{{Cite journal |last1=Malkamäki |first1=Arttu |last2=D’Amato |first2=Dalia |last3=Hogarth |first3=Nicholas J. |last4=Kanninen |first4=Markku |last5=Pirard |first5=Romain |last6=Toppinen |first6=Anne |last7=Zhou |first7=Wen |date=July 2019 |title=Corrigendum of "A systematic review of the socio-economic impacts of large-scale tree plantations, worldwide" [Glob. Environ. Change 53 (2018) 90–103] |url=http://dx.doi.org/10.1016/j.gloenvcha.2019.101931 |journal=Global Environmental Change |volume=57 |pages=101931 |doi=10.1016/j.gloenvcha.2019.101931 |bibcode=2019GEC....5701931M |issn=0959-3780 |s2cid=197773639}}</ref>

=== Biodiversity loss ===
Reforesting sometimes results in extensive canopy creation that prevents growth of diverse vegetation in the shadowed areas and generating soil conditions that hamper other types of vegetation. Trees used in some reforesting efforts (for example, ''[[Eucalyptus globulus]]'') tend to extract large amounts of moisture from the soil, preventing the growth of other plants. The [[European Commission]] found that, in terms of environmental services, it is better to avoid [[deforestation]] than to allow for deforestation to subsequently reforest, as the former leads to irreversible effects in terms of [[biodiversity loss]] and [[soil degradation]].<ref>{{cite web|title=Press corner|url=https://ec.europa.eu/commission/presscorner/detail/en/MEMO_08_632|access-date=28 September 2020|website=European Commission – European Commission|language=en}}</ref>

The effects reforestation has on biodiversity is not limited to just other forms of vegetation, it can affect all forms of living organisms all contained in the present ecosystem.<ref>{{Cite journal |last1=Aerts |first1=Raf |last2=Honnay |first2=Olivier |date=2011-11-24 |title=Forest restoration, biodiversity and ecosystem functioning |journal=BMC Ecology |volume=11 |issue=1 |pages=29 |doi=10.1186/1472-6785-11-29 |issn=1472-6785 |pmc=3234175 |pmid=22115365 |doi-access=free |bibcode=2011BMCE...11...29A }}</ref> Due to the major role trees have on ecosystems it is important to better understand components like the ecosystem, waterways, and species present in areas that are being re-planted.&nbsp;Prior research helps limit the depletion of biodiversity which can hinder medicinal discoveries, and alter gene flow in organisms.<ref name="Cunningham 301–317" />

A debated issue in managed reforestation is whether the succeeding forest will have the same [[biodiversity]] as the original forest. If the forest is replaced with only one species of tree and all other vegetation is prevented from growing back, a [[monoculture]] forest similar to agricultural crops would be the result. However, most reforestation involves the planting of different selections of seedlings taken from the area, often of multiple species.<ref name="kennethmarendefoundation.com">{{cite web |title=Archived copy |url=http://kennethmarendefoundation.com/index.php/reforestation-problem |url-status=dead |archive-url=https://web.archive.org/web/20141111185724/http://kennethmarendefoundation.com/index.php/reforestation-problem |archive-date=2014-11-11 |access-date=2013-03-27}}</ref><ref name="RTR">{{Citation |author1=Goosem, Stephen P |title=Repairing the rainforest |publication-date=2013 |year=2013 |edition=2 |publisher=Wet Tropics Management Authority; [Tarzali, Queensland] : Biotropica Australia |isbn=978-1-921591-66-2 |author2=Tucker, Nigel I. J. |author3=Wet Tropics Management Authority, (issuing body.)}}</ref>

=== Stored carbon being released ===
There is also the risk that, through a [[wildfire|forest fire]] or [[Forest pathology|insect outbreak]], much of the stored carbon in a reforested area could make its way back to the atmosphere.<ref name="Canadell">{{Cite journal |last=Canadell |first=J.G. |author2=M.R. Raupach |date=2008-06-13 |title=Managing Forests for Climate Change |url=http://www.globalcarbonproject.org/global/pdf/canadell%26raupach2008_managingforests.science.pdf |journal=Science |volume=320 |issue=5882 |pages=1456–1457 |bibcode=2008Sci...320.1456C |citeseerx=10.1.1.573.5230 |doi=10.1126/science.1155458 |pmid=18556550 |s2cid=35218793}}</ref> Furthermore, the probability that legacy carbon will be released from soil is higher in younger boreal forests.<ref>{{cite journal |last1=Walker |first1=Xanthe J. |last2=Baltzer |first2=Jennifer L. |last3=Cumming |first3=Steven G. |last4=Day |first4=Nicola J. |last5=Ebert |first5=Christopher |last6=Goetz |first6=Scott |last7=Johnstone |first7=Jill F. |last8=Potter |first8=Stefano |last9=Rogers |first9=Brendan M. |last10=Schuur |first10=Edward A. G. |last11=Turetsky |first11=Merritt R. |last12=Mack |first12=Michelle C. |author-link12=Michelle Cailin Mack|title=Increasing wildfires threaten historic carbon sink of boreal forest soils |journal=Nature |date=August 2019 |volume=572 |issue=7770 |pages=520–523 |doi=10.1038/s41586-019-1474-y |pmid=31435055 |bibcode=2019Natur.572..520W |s2cid=201124728 |url=https://www.nature.com/articles/s41586-019-1474-y |access-date=28 September 2020 |language=en |issn=1476-4687}}</ref> An example of this can be seen in the peatlands in Central Africa, which house an abundance of carbon in the mud called peat. Much like the forest fire or insect outbreak which can harm tropical rainforests, money can also be seen an incentive to harm forests and be paid off to protect it.<ref>{{Cite news |last=Maclean |first=Ruth |date=2022-02-22 |title=What Do the Protectors of Congo's Peatlands Get in Return? |language=en-US |work=The New York Times |url=https://www.nytimes.com/interactive/2022/02/21/headway/peatlands-congo-climate-change.html |access-date=2022-05-16 |issn=0362-4331}}</ref> The global greenhouse gas emissions caused by damage to tropical rainforests may be underestimated by a factor of six.<ref>{{cite news |title=Climate emissions from tropical forest damage 'underestimated by a factor of six' |url=https://www.theguardian.com/environment/2019/oct/31/climate-emissions-from-tropical-forest-damage-underestimated-by-a-factor-of-six |access-date=28 September 2020 |work=The Guardian |date=31 October 2019 |language=en}}</ref>

Also the possible harvesting and utilization of wood from reforested areas, limits the permanence of carbon sequestered through reforestation. For example, it was found that nearly half of the pledges under the [[Bonn Challenge]] were areas earmarked for commercial wood use.<ref>{{Cite journal |last1=Lewis |first1=Simon L. |last2=Wheeler |first2=Charlotte E. |last3=Mitchard |first3=Edward T. A. |last4=Koch |first4=Alexander |date=April 2019 |title=Restoring natural forests is the best way to remove atmospheric carbon |journal=Nature |language=en |volume=568 |issue=7750 |pages=25–28 |doi=10.1038/d41586-019-01026-8|pmid=30940972 |bibcode=2019Natur.568...25L |s2cid=91190309 |doi-access=free }}</ref>

Additionally the effects of afforestation and reforestation will be farther in the future than those of proforestation (the conservation of intact forests).<ref name=":9">{{cite web |title=Why Keeping Mature Forests Intact Is Key to the Climate Fight |url=https://e360.yale.edu/features/why-keeping-mature-forests-intact-is-key-to-the-climate-fight |website=Yale E360 |access-date=28 September 2020}}</ref> It takes much longer − several decades − for the benefits for global warming to manifest to the same [[carbon sequestration]] benefits from mature trees in tropical forests and hence from limiting deforestation.<ref name=":10">{{cite web |title=Would a Large-scale Reforestation Effort Help Counter the Global Warming Impacts of Deforestation? |url=https://blog.ucsusa.org/elliott-negin/would-reforestation-help-counter-deforestation |website=Union of Concerned Scientists |access-date=28 September 2020 |date=1 September 2012}}</ref>

Some researchers note that instead of planting entirely new areas, reconnecting forested areas and restoring the edges of forest, to protect their mature core and make them more resilient and longer-lasting, should be prioritized.<ref name=":11">{{cite web |last1=Mackey |first1=Brendan |last2=Dooley |first2=Kate |title=Want to beat climate change? Protect our natural forests |url=https://theconversation.com/want-to-beat-climate-change-protect-our-natural-forests-121491 |website=The Conversation |date=6 August 2019 |access-date=28 September 2020 |language=en}}</ref>

=== Implementation challenges ===
There are some implementation challenges
* Seed shortage: the Seed to Forest Alliance was founded in 2022 in response to a global seed shortage. It will promote the establishment of national seed banks, while focusing on the tropics and biodiversity hotspots.<ref>{{Cite web |date=2022-09-21 |title=New Alliance Launched to Tackle Global Seed Shortage and Scale Reforestation |url=https://www.businesswire.com/news/home/20220915005905/en/New-Alliance-Launched-to-Tackle-Global-Seed-Shortage-and-Scale-Reforestation |access-date=2023-10-21 |website=www.businesswire.com |language=en}}</ref>
* Seedling survival rate: a common challenge for reforestation is the low survival rate of seedlings. Planted trees often do not mature, for example due to difficult climatic conditions or insufficient care after planting.<ref name=":5" /><ref>{{Cite journal |last1=Banin |first1=Lindsay F. |last2=Raine |first2=Elizabeth H. |last3=Rowland |first3=Lucy M. |last4=Chazdon |first4=Robin L. |last5=Smith |first5=Stuart W. |last6=Rahman |first6=Nur Estya Binte |last7=Butler |first7=Adam |last8=Philipson |first8=Christopher |last9=Applegate |first9=Grahame G. |last10=Axelsson |first10=E. Petter |last11=Budiharta |first11=Sugeng |last12=Chua |first12=Siew Chin |last13=Cutler |first13=Mark E. J. |last14=Elliott |first14=Stephen |last15=Gemita |first15=Elva |date=January 2023 |title=The road to recovery: a synthesis of outcomes from ecosystem restoration in tropical and sub-tropical Asian forests |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |language=en |volume=378 |issue=1867 |doi=10.1098/rstb.2021.0090 |issn=0962-8436 |pmc=9661948 |pmid=36373930}}</ref>