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Mechanisms underlying the loss of ecological resilience and a shift to an alternate regime with lower ecosystem service provisioning continues to be a leading debate in ecology, particularly in cases where evidence points to human actions and decision-making as the primary drivers of resilience loss and regime change. In this paper, we introduce the concept of coerced resilience as a way to explore the interplay among social power, ecological resilience, and fire management, and to better understand the unintended and undesired regime changes that often surprise ecosystem managers and governing officials. Philosophically, coercion is the opposite of freedom, and uses influence or force to gain compliance among local actors. The coercive force imposed by societal laws and policies can either enhance or reduce the potential to manage for essential structures and functions of ecological systems and, therefore, can greatly alter resilience. Using a classical fire-dependent regime shift from North America (tallgrass prairie to juniper woodland), and given that coercion is widespread in fire management today, we quantify relative differences in resilience that emerge in a policy-coerced fire system compared to a theoretical, policy-free fire system. Social coercion caused large departures in the fire conditions associated with alternative grassland and juniper woodland states, and the potential for a grassland state to emerge to dominance became increasingly untenable with fire as juniper cover increased. In contrast, both a treeless, grassland regime and a co-dominated grass-tree regime emerged across a wide range of fire conditions in the absence of policy controls. The severe coercive forcing present in fire management in the Great Plains, and corresponding erosion of grassland resilience, points to the need for transformative environmental governance and the rethinking of social power structures in modern fire policies.

Climate–fire interactions constrain potential woody plant cover and stature in North American Great Plains grasslands

https://doi.org/10.1111/geb.12752

Scholtz, R. ; Fuhlendorf, S. D. ; Archer, S. R. ( August 2018 , Global Ecology and Biogeography)

Abstract Aim

Disturbances such as fire operate against a backdrop of constraints imposed by climate and soils to influence grass–woody plant abundance. However, little is known of how these factors interact to determine the upper limits of woody cover and stature in grasslands, in which shrub/tree abundance has been increasing globally.

Location

Kansas, Oklahoma, Texas, USA.

Time period

2004–2014.

Major taxa studied

Angiosperms and gymnosperms.

Methods

Using a database of 1,466 sites and quantile regression to derive precipitation‐based upper limits to woody cover and height within grasslands of the central/southern Great Plains, USA, we assessed how soil texture and climate‐related fire probabilities [two groups; low fire probability, P(F_low), versus high fire probability, P(F_hi)] might influence realization of the climate potential.

Results

Soil texture had no substantive influence on regional‐scale woody cover, but taller plants were predicted on sandy soils. Woody plant height potential increased linearly with increasing annual precipitation, becoming asymptotic atc. 800 mm for both the P(F_low) and the P(F_hi) fire groups, after which P(F_low) areas were predicted to support taller plants. Potential woody cover also increased linearly with annual precipitation untilc. 800 mm, after which predictions of maximum % cover were similar under both fire groups.

Main conclusions

Precipitation was the overriding factor constraining potential woody cover and height, particularly in drier regions, with fire playing a minor role at these regional scales. In contrast to height potential, cover potential remained similar for both P(F_low) and P(F_hi) sites. Dynamic adjustments in woody plant architecture and allocation to foliage and stems, wherein areal cover is maintained when height is suppressed has implications for remote sensing, primary production and biogeochemical processes. Our analyses indicate drier grasslands [< 800 mm mean annual precipitation (MAP)] undergoing woody plant encroachment have the potential to become shrublands (e.g. short woody plants, low cover), whereas wetter areas have the potential to become woodland or forest (taller woody plants, high cover).