Predicting Chronic Climate-Driven Disturbances and Their Mitigation

Abstract

Society increasingly demands the stable provision of ecosystem resources to support our population. Resource risks from climate-driven disturbances, including drought, heat, insect outbreaks, and wildfire, are growing as a chronic state of disequilibrium results from increasing temperatures and a greater frequency of extreme events. This confluence of increased demand and risk may soon reach critical thresholds. We explain here why extreme chronic disequilibrium of ecosystem function is likely to increase dramatically across the globe, creating no-analog conditions that challenge adaptation. We also present novel mechanistic theory that combines models for disturbance mortality and metabolic scaling to link size-dependent plant mortality to changes in ecosystem stocks and fluxes. Efforts must anticipate and model chronic ecosystem disequilibrium to properly prepare for resilience planning.

Contrasting resistance and resilience to extreme drought and late spring frost in five major European tree species

“…Our results demonstrate contrasting resistance and resilience of major European tree species to ECEs with spruce and larch exhibiting the highest vulnerability to severe droughts. Thus, if the frequency of ECEs increases, competition among tree species may change, resulting in structural and functional changes within forest ecosystems (McDowell et al, ). Besides, our results underline that spruce and larch are not only constrained by severe spring droughts but also by warmer summer temperatures resulting in a strong dependency of tree growth to mean summer temperature in relation to elevation.…”

“…Extreme droughts are expected to increase in frequency, magnitude, and spatial extent (Ballester, Rodó, & Giorgi, 2010;McDowell et al, 2018;Stott, 2016). To what extent the frequency of damaging spring frosts may change remains more uncertain and site specific, because both spring phenology and the last spring frosts are currently advancing (Vitasse, Schneider, Rixen, Christen, & Rebetez, 2018).…”

A theory of pulse dynamics and disturbance in ecology

“…, McDowell et al. ). In turn, pulse events can affect the responses of ecosystems to these influences, e.g., increasing invasion rates (Hobbs and Huenneke ) and accelerating or otherwise affecting responses to climate warming (DeFrenne et al.…”

Climate-driven disturbances in the San Juan River sub-basin of the Colorado River

“…Water yields and peak streamflows in North American river basins are anticipated to either increase, decrease, or show no response to changing forest cover (see Table 2 in Adams et al, 2012;Schnorbus et al, 2010;Guardiola-Claramonte et al, 2011;Somor, 2010;McDowell et al, 2018). Causes of the reported changes have been related to topography (Schnorbus et al, 2010) and climate variability .…”

“…However, in general, ESMs contain simplifications of the explicit scenario of evolving landscape ecology and do not include a full suite of disturbances (e.g., pests, drought, wildfire), which are extremely difficult to simulate due to the computational expense associated with the coupling between disturbances and the disparate timescales involved. Therefore, current ESMs are limited in their assessment of the feedbacks driven by the disturbances and the threat of complete system crash, e.g., the loss of large tracts of forests and/or strongly declining water resources (McDowell et al, 2018).…”