Minimal mortality and rapid recovery of the dominant shrub Larrea tridentata following an extreme cold event in the northern Chihuahuan Desert

Abstract

Questions Woody encroachment into grasslands is a worldwide phenomenon partially influenced by climate change, including extreme weather events. Larrea tridentata is a common shrub throughout the warm deserts of North America that has encroached into grasslands over the past 150 years. Physiological measurements suggest that the northern distribution of L. tridentata is limited by cold temperatures; thus extreme winter events may slow or reverse shrub expansion. We tested this limitation by measuring the response of individual L. tridentata shrubs to an extreme winter cold (−31°C) event to assess shrub mortality and rate of recovery of surviving shrubs. Location Sevilleta National Wildlife Refuge, Socorro County, New Mexico, USA. Methods Canopy dieback and recovery following an extreme cold event were measured for 869 permanently marked individual L. tridentata shrubs in grass–shrub ecotone and shrubland sites. Individual shrubs were monitored for amount of canopy dieback, rate of recovery, and seed set for three growing seasons after the freeze event. Results Shrubs rapidly suffered a nearly complete loss of canopy leaf area across all sites. Although canopy loss was high, mortality was low and 99% of shrubs resprouted during the first growing season after the freeze event. Regrowth rates were similar within ecotone and shrubland sites, even when damage by frost was larger in the latter. After three years of recovery, L. tridentata canopies had regrown on average 23–83% of the original pre‐freeze canopy sizes across the sites. Conclusions We conclude that isolated extreme cold events may temporarily decrease shrubland biomass but they do not slow or reverse shrub expansion. These events are less likely to occur in the future as regional temperatures increase under climate change.

Tropicalization of temperate ecosystems in North America: The northward range expansion of tropical organisms in response to warming winter temperatures

“…In the desert ecosystems of the arid southwestern United States and northwestern Mexico, extreme freeze events control the northern and altitudinal distribution of foundation plant species like the giant saguaro cactus (Carnegiea gigantea; Figure S1; Niering et al, 1963;Shreve, 1911;Steenbergh & Lowe, 1976), desert ironwood tree (Olneya tesota; Turnage & Hinckley, 1938), organ pipe cactus (Stenocereus thurberi; Bowers, 1981;Parker, 1988;Turnage & Hinckley, 1938), senita (Pachycereus schottii; Felger & Lowe, 1967;Nobel, 1980c;Turnage & Hinckley, 1938), creosote bush (Larrea tridentata; D' Odorico et al, 2010;Ladwig et al, 2019;Pockman & Sperry, 1997), Joshua tree (Yucca brevifolia; Dole et al, 2003;Loik et al, 2000;Smith et al, 1983), little-leaf paloverde (Parkinsonia microphylla), and many others. Landscape-scale pulses of adult plant death in the Sonoran Desert are caused by catastrophic freezes (Bowers, 1981;McAuliffe, 1996;Steenbergh & Lowe, 1977).…”

Watching plants’ dance: movements of live and dead branches linked to atmospheric water demand

“…Many creosote, evergreen shrubs, suffered extreme (>90%) canopy dieback. Although there was very little creosote mortality (Ladwig et al 2019), the shrubs were left with a unique crown of dead branches. In the ensuing years, shrub canopies regrew from the base of each plant.…”

Multi-Temporal and Time-Lag Responses of Terrestrial Net Ecosystem Productivity to Extreme Climate from 1981 to 2019 in China

“…A possible reason is that extreme climate cause short-term carbon loss in shrub ecosystems, and the rapid regeneration of shrubs after extreme climate accelerates regional carbon cycling [20]. This observation is supported by the NEP response of Chihuahuan Desert shrubs in North America to extreme climate: the shrub canopy areas decrease sharply and biomass decreases sharply, but the mortality rate is very low (0.8%) and 99% of shrubs regenerate and grow larger and more dispersed canopies after the freezing event, promoting a quick restoration of the ecosystem's carbon absorption [84]. Similar carbon cycle promotion phenomena have been observed when shrub seedlings regenerate after hurricanes or fires [85].…”