Fire facilitates warming-induced upward shifts of alpine treelines by altering interspecific interactions

Abstract

Key messageModerate-severity fire disturbances can accelerate upslope shifts of alpine treelines by reducing interspecific interactions, providing additional evidence for the species interaction mechanism in controlling treeline dynamics.

Alpine treeline ecotone stasis in the face of recent climate change and disturbance by fire

“…How species respond to changing climates at local scales will depend on how edaphic and biological characteristics interact with species physiological limits, traits such as dispersal, and interactions with disturbance (type, frequency, severity). While climate is considered a key determinant of alpine treeline position [1], and hence treeline position is likely responsive to climate warming, disturbance may also play a critical but poorly understood role [12,13,49]. Using a revisitation approach at the alpine treeline in Australia where fire has been both extensive and recurrent during the last few decades [44], we found that a limited number of saplings of the alpine treeline species E. pauciflora recruited above the treeline, but this depended on the frequency of fire.…”

“…Understanding how disturbance, such as fire, impacts on treeline persistence and expansion is clearly crucial for interpreting treeline population dynamics [49,59]. Fires, particularly at short-intervals, have been found to cause treeline depression across a range of global treelines [28,[60][61][62].…”

“…Fires, particularly at short-intervals, have been found to cause treeline depression across a range of global treelines [28,[60][61][62]. Conversely, fires have also been found to accelerate the effect of rising temperatures through reducing competition with surrounding vegetation [15,59,49,63]. Fire may assume an even greater importance in the Australian Alps in the future, with temperatures predicted to increase by 1.4-3.8˚C over the next century for south-eastern Australia [64], increasing the frequency of high fire danger days by as much as 70% by 2050 [65,66].…”

Wildfires as an ecosystem service

“…By opening gaps, wildfires may help species replacement to occur more quickly than in closed conditions, especially in ecosystems dominated by non‐resprouting (fire‐killed) species (eg Wang et al . ). In addition, these new gaps for recruitment select for individuals (ie genotypes) better suited to the new climate, thereby enhancing adaptation to drier conditions.…”

Responses and feedback of the Tibetan Plateau’s alpine ecosystem to climate change

“…在 青海玉树、西藏昌都和林芝地区, 川西云杉树线爬升 25 m [27] , 而急尖长苞冷杉树线仅上升0~9 m [28] . 在滇西 北的横断山区, 长苞冷杉和大果红杉树线爬升幅度分 别为19~28和0~67 m [25,29,30] . 总之, 过去100年来青藏高 [25] .…”