Physiological strategies explain mortality differences among ecologically and culturally significant Australian desert plants following a hotter drought

Abstract

Climate change-induced drought and heatwave events (hotter droughts) are causing mass plant dieback events globally. Recently, Uluru-Kata Tjuta National Park (UKTNP) in central Australia experienced a widespread plant dieback (mortality) event. Anangu (Traditional Owners) are concerned about the resulting negative impacts to ecosystems and wish to understand more about the underlying causes of mass plant death. With a focus on ecologically and culturally significant species chosen by Anangu, we measured morphological and physiological traits to characterize differences in physiological strategy underpinning the patterns of dieback observed at UKTNP. Maintenance of leaf relative water content (RWC) was the leaf trait that best predicted dieback severity, with all species that had low levels of dieback exhibiting drought-avoidance strategies where RWC was maintained between spring and summer. Most species with moderate and high levels of dieback exhibited drought-tolerance strategies, evidenced by large declines in seasonal RWC and higher wood densities. However, two small shrub species with high dieback severity may have died due to failure of different physiological mechanisms—one of hydraulic failure via drought tolerance and one of carbon limitation via drought avoidance—highlighting the importance of considering species-specific trait combinations to understand drivers of mortality. Understanding the drivers of dieback will help to support Anangu-led land stewardship and conserve the natural and cultural values of this important landscape.

Pitjantjatjara abstract: Kuwari, punu munu ukiri tjuta piltiringanyi manta winkingka panya ailurungka munu kuli pulkangka. Mungatu, Uluru-Kata Tjuta National Parkangka, ailuru pulkangku piltira wiyanu punu munu ukiri tjuta Anangu tjutaku. Nganana mukuringanyi nintiringkutjaku nyaa nguru punu munu ukiri tjuta wiyaringu, ka punu kutjupa tjuta palyatu ngaranyi. Nganana kulini punu munu ukiri wankatu ngaranyi panya kapi ngarinyi nyarlpingka. Tjingurula kulini punu pilti tjutangku putu kapi Kanyini nyarlpingka. Tjinguru kapi putu pakani nyarlpinguru. Pukara munu kaliny-kalinypa tjuta wiyaringu ailurungka. Tjinguru pukarangku kapi kawalanu aturu ungu. Tjinguru kaliny-kalinypangku mai munu tjuratja kawalanu aturu ungu. Nyangatjalanya nintini panya punu wiyaringanyi nyanga paluru tjanalanguru, punu kutjupa tjuta tjinguru wiyaringanyi kutjupa kutjupanguru. Nganana tjungu warkarira nintiringkutjaku panya ailurungku ngura nganampa piltini. Nyanga palulanguru nganana ngura nganampa wirura atunmangkuntjaku.