Imiphumela kazwelonke ibonisa ukuthi ukumboza kwezihlahla ezindaweni zasemadolobheni e-United States kuyehla ngenani lezihlahla ezingaba yizigidi ezi-4 ngonyaka, ngokocwaningo lwe-US Forest Service olushicilelwe muva nje ku-Urban Forestry & Urban Greening.
Ukumbozwa kwezihlahla emadolobheni angu-17 kwangu-20 ahlaziywe ocwaningweni kwehlile ngenkathi amadolobha angu-16 abona ukwanda kwekhava engangeni, okuhlanganisa umgwaqo ogandayiwe kanye nophahla. Umhlaba owalahleka izihlahla wawuguqulwa ube utshani noma umhlabathi, umboze ongangeni noma umhlabathi ongenalutho.
Emadolobheni angama-20 ahlaziywayo, amaphesenti amakhulu kakhulu okulahlekelwa kwaminyaka yonke ekhava yesihlahla kwenzeka eNew Orleans, eHouston nase-Albuquerque. Abacwaningi bekulindeleke ukuthi bathole ukulahlekelwa okumangalisayo kwezihlahla eNew Orleans futhi bathi kungenzeka kakhulu ukuthi kungenxa yokucekelwa phansi kweSiphepho u-Katrina ngo-2005. Ikhava yezihlahla yayisukela kokuphezulu okungamaphesenti angu-53.9 e-Atlanta kuya kokuphansi ngamaphesenti angu-9.6 eDenver kuyilapho ukumbozwa okuphelele kuhluka kusuka kumaphesenti angu-61.1 e-Naville 17.7 kuya e-New York City kuya e-New York City. Amadolobha anokwanda okukhulu kwaminyaka yonke kwekhava elingenakunyakaziswa kwakuyi-Los Angeles, i-Houston ne-Albuquerque.
“Amahlathi ethu asemadolobheni angaphansi kwengcindezi, futhi kuzodinga ukuthi sonke sisebenze ndawonye ukuze sithuthukise impilo yalezi zindawo ezibalulekile eziluhlaza,” kusho iNhloko Yenkonzo Yamahlathi yase-US uTom Tidwell. “Izinhlangano zomphakathi kanye nabahleli bomasipala bangasebenzisa i-i-Tree ukuze bahlaziye izihlahla zabo, futhi banqume izinhlobo ezingcono kakhulu nezindawo zokutshala ezindaweni ezihlala kuzo. Akukephuzi kakhulu ukubuyisela amahlathi ethu asemadolobheni – isikhathi manje sokuthi sikuguqule lokhu.”
Izinzuzo ezitholakala ezihlahleni zasemadolobheni zinikeza imbuyiselo enkulu ngokuphindwe kathathu kunezindleko zokunakekelwa kwesihlahla, okungaba ngu-$2,500 kumasevisi emvelo afana nezindleko ezincishisiwe zokushisisa nokupholisa ngesikhathi sokuphila kwesihlahla.
Abacwaningi bamahlathi u-David Nowak no-Eric Greenfield be-US Forest Service's Northern Research Station basebenzisa isithombe sesathelayithi ukuze bathole ukuthi ikhava yesihlahla iyancipha ngesilinganiso esingaba ngamaphesenti angu-0.27 wendawo ngonyaka emadolobheni ase-US, okulingana cishe namaphesenti angu-0.9 ekhava yezihlahla zasemadolobheni ezikhona ezilahlekayo minyaka yonke.
Ukuhunyushwa kwesithombe kwezithombe zedijithali ezibhanqiwe kunikeza izindlela ezilula, ezisheshayo nezinezindleko eziphansi zokuhlola izinguquko ngokwezibalo phakathi kwezinhlobo ezahlukene zekhava. Ukusiza ekulinganiseni izinhlobo zekhava ngaphakathi kwendawo, ithuluzi lamahhala, i-Isihlahla se-Canopy, ivumela abasebenzisi ukuthi bahumushe isithombe-idolobha besebenzisa izithombe ze-Google.
"Izihlahla ziyingxenye ebalulekile yendawo yasemadolobheni," ngokusho kukaMichael T. Rains, uMqondisi weNorthern Research Station. “Babamba iqhaza ekuthuthukiseni izinga lomoya namanzi futhi banikeze izinzuzo eziningi zemvelo nezenhlalo. Njengoba iNhloko yethu Yenkonzo Yamahlathi isho, '…izihlahla zasemadolobheni ziyizihlahla ezisebenza kanzima eMelika.' Lolu cwaningo luwumthombo omkhulu wamadolobha anobukhulu obuhlukahlukene ezweni lonke.”
UNwak noGreenfield baphothule ukuhlaziya okubili, okukodwa kwamadolobha angama-20 akhethiwe kanye nelinye kwezindawo zasemadolobheni kazwelonke, ngokuhlola umehluko phakathi kwezithombe zakamuva zasemoyeni zedijithali okungenzeka kanye nezithombe ezithandanayo eduze kakhulu ngangokunokwenzeka eminyakeni emihlanu ngaphambi kwalolo suku. Izindlela bezifana kodwa amadethi esithombe nezinhlobo bezihluka phakathi kokuhlaziya okubili.
"Ukulahlekelwa kwezihlahla bekuzoba phezulu ukube bekungengenxa yemizamo yokutshala izihlahla eyenziwe ngamadolobha eminyakeni embalwa edlule," ngokusho kukaNowak. “Imikhankaso yokutshala izihlahla iyasiza ekwandiseni, noma okungenani ukunciphisa ukulahleka kwezihlahla zasemadolobheni, kodwa ukuhlehlisa lo mkhuba kungase kudinge izinhlelo ezisabalele, eziphelele nezididiyelwe ezigxile ekusimamiseni umbhede wezihlahla.”