A Tsibirin Heat na Urban, Zippy Red Oaks
By DOUGLAS M. MAIN
Jaridar New York Times, Afrilu 25, 2012
Jajayen itacen oak a cikin Central Park sun girma har sau takwas cikin sauri fiye da 'yan uwansu da aka noma a wajen birni, mai yiwuwa saboda tasirin "tsibirin zafi" na birni, Masu bincike na Jami'ar Columbia sun ba da rahoto.
Masu binciken sun dasa tsire-tsire na itacen oak na asali a cikin bazara na 2007 da 2008 a wurare hudu: a arewa maso gabashin Central Park, kusa da 105th Street; a cikin gandun daji guda biyu a cikin kwarin Hudson na kewayen birni; kuma kusa da Tafkin Ashokan na birni a cikin tsaunin Catskill kimanin mil 100 daga arewacin Manhattan. A ƙarshen kowane lokacin rani, bishiyoyin birni sun sanya ƙwayoyin halitta sau takwas fiye da waɗanda aka girma a wajen birni, bisa ga binciken su, wanda aka buga a cikin mujallar Tree Physiology.
"Tsarkin ya girma sosai a cikin birni, tare da raguwar girma yayin da kuke samun nisa daga birnin," in ji jagorar marubucin binciken, Stephanie Searle, wacce jami'ar Columbia ce ta kammala karatun digiri a lokacin da aka fara binciken kuma yanzu ita ce mai binciken manufofin biofuels a Majalisar kasa da kasa kan sufuri mai tsafta a Washington.
Masu binciken sun yi hasashen cewa yanayin zafi na Manhattan - har zuwa digiri takwas mafi girma a cikin dare fiye da kewayen karkara - na iya zama babban dalili na saurin girma na itatuwan oak na Central Park.
Amma duk da haka yanayin zafi a fili ɗaya ne kawai daga cikin bambance-bambance tsakanin wuraren karkara da birane. Don keɓe rawar da thermostat ta taka, masu binciken sun kuma tayar da itacen oak a cikin dakin gwaje-gwaje inda dukkan yanayi suka kasance iri ɗaya ne, ban da yanayin zafi, wanda aka canza don yin kwaikwayi yanayi daga filayen filayen daban-daban. Tabbatacce, sun lura da saurin girma ga itatuwan oak da aka tashe a cikin yanayi masu zafi, kamar waɗanda aka gani a filin, in ji Dokta Searle.
Ana tattauna abin da ake kira tasirin tsibiri na zafi na birni dangane da yiwuwar mummunan sakamako. Amma binciken ya nuna zai iya zama alheri ga wasu nau'ikan. "Wasu kwayoyin halitta na iya bunƙasa akan yanayin birane," in ji wani marubuci, Kevin Griffin, masanin ilimin halittar bishiya a Lamont-Doherty Earth Observatory a Columbia, a cikin wata sanarwa.
Sakamakon ya yi daidai da na a Nazarin 2003 a cikin Nature wanda ya sami girma girma a tsakanin itatuwan poplar da aka girma a cikin birni fiye da na waɗanda ake girma a cikin karkarar da ke kewaye. Amma binciken na yanzu ya ci gaba ta hanyar ware tasirin yanayin zafi, in ji Dokta Searle.
Jajayen itacen oak da danginsu sun mamaye dazuzzuka da yawa daga Virginia zuwa kudancin New England. Kwarewar jajayen itatuwan oak na Central Park na iya ba da alamu ga abin da ka iya faruwa a cikin dazuzzuka a wasu wurare yayin da yanayin zafi ke hauhawa cikin shekaru da yawa masu zuwa tare da ci gaban canjin yanayi, masu binciken sun ba da shawarar.