Resist, Accept, or Direct: Using Early Warning Signals to Manage Woody Encroachment in the Great Plains

New research pairs satellite imagery with the RAD management framework to improve grassland conservation

Woody plant encroachment is one of the most significant and impactful threats facing the grasslands of the Great Plains, leading to lost profits for producers, more severe wildfires, less water, increases in insect-borne diseases, decreased school funding, degraded wildlife habitat, and more.

Proactive conservation that targets intact grasslands is the most effective and efficient way to address woody plant encroachment in the Great Plains. But determining where to prioritize conservation treatments and what types of conservation efforts to implement at the scale needed to work across the entire Great Plains grassland biome is a challenge.

New research from WLFW-affiliated researchers at the University of Nebraska-Lincoln used satellite mapping technology and the Resist-Accept-Direct (RAD) framework (developed by the U.S. Geological Survey) to help managers and landowners better understand where to focus conservation and what types of conservation practices to implement.

Satellite mapping technologies and derivative products, like the “Early Warning for Woody Transitions Monitoring Project,” which was used for this research, can provide managers and landowners with spatially explicit maps and information on where and how severely grasslands are transitioning to woody dominance. Combining these technologies with well-understood management frameworks like the RAD can help improve the general decision-making of resource managers and communities addressing woody encroachment and grassland loss.

The team, led by Rheinhardt Scholtz, examined transition warning signals at different spatial scales – from small patches to entire ecoregions – across the entire biome. They found that some areas exhibited only a few signals of transition, while others exhibited multiple signals.

The team then placed the different areas within the three tiers of the RAD framework. Those areas exhibiting transition warnings at fewer scales were placed into the “resist” category, those showing warning transitions at multiple, but not all scales, were placed into the “direct” category, and those showing transitions at all, or nearly all, scales were placed into the “accept” category.

Generally, the team found that opportunities to resist woody transitions decreased from 85% to 60% between 1990 and 2020. The researchers found that opportunities to resist grassland transitions declined in all Great Plains ecoregions from 1990-2020. In 1990, 12 of 14 ecoregions had more grassland areas that were high candidates for resisting transitions, but in 2020, only seven ecoregions fell into the resist category.

In 2020, 11% of the Great Plains biome exhibited early warning transition signals across all scales measured, a fourfold increase since 1990. Additionally, 30% of the biome exhibited early warning signals across multiple but not all scales, highlighting the need to determine the types of management efforts that can maintain fragmented grassland legacies within a woody-dominated matrix.

Importantly, the team paired their analysis with suggested management actions, which are intended to help with conservation planning and management. For example, in areas that fall into the accept category, the authors suggested management actions that reduce wildfire danger for homes and property, like the Firewise USA program. In areas that fall into the resist category, the authors suggested actions and policies that conserve and defend intact grasslands like the USDA-NRCS’s Great Plains Grassland Initiatives and Working Lands for Wildlife’s Framework for Conservation Action in the Great Plains Biome. For more specific recommendations, see the table below.

Today, the northern and western Great Plains (High Plains, Nebraska Sandhills, Northern Glaciated Plains, Northwestern Glaciated Plains, Northwestern Great Plains ecoregions) had the lowest amount of area exhibiting multi-scale warning signals, making them the best locations for resisting woody plant transitions. However, these areas were on a trajectory that mirrored several ecoregions in the southern and central Great Plains, where some of the highest rates of increase in multi-scale early warning signals were observed.

In the central and eastern Great Plains, most areas fell into the direct or accept categories, but small pockets of areas did fit into the resist category.

This research demonstrates how new technologies and existing ecological management frameworks can be paired to better inform management decisions and produce longer-lasting, more durable conservation results more efficiently than reactive, scattered conservation practices.

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RECONCILING SCALE USING THE RESIST-ACCEPT-DIRECT (RAD) FRAMEWORK TO IMPROVE MANAGEMENT OF WOODY ENCROACHMENT IN GRASSLANDS

Abstract: Implementing strategies to navigate large-scale ecological transitions in grasslands is one of this century’s greatest conservation challenges. In the US Great Plains, managing areas impacted by woody transitions have been reactive, short-lived, costly, and ineffective.

Along with current technological innovation in rangeland monitoring, the promise of early warning science is to provide managers with sufficient time to be better prepared for novel signals of ecological change. Combining the science of early warning signals and frameworks such as the Resist – Accept – Direct (RAD) can provide land managers with guidelines to identify proactive strategies when facing ecological change.

Using this approach, we found that opportunities to resist woody transitions decreased from 84 % to 60 % between 1990 and 2020 over the entire biome but remained highest in the northern and western Great Plains, which contributes to large scale conservation targets. These are key areas to prioritize resist opportunities. In contrast, 11 % of the biome exhibited early warning transition signals across all hierarchical scales by 2020, a fourfold increase since 1990. Lastly by 2020, 30 % of the biome exhibited early warning signals across multiple but not all scales. Here, efforts may be more effective when management is directed to conserve fragmented grassland legacies within a woody-dominated matrix and avoid large-scale monocultures of problematic encroaching woody species.

Our multi-scale study indicates that 1) anchoring to the last remaining grassland core areas with no early warning of transitions and 2) strategically investing in these intact grasslands may provide the best results for grassland conservation.

Acknowledgements: This material is based upon work supported by the National Science Foundation under Grant No. 1920938. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Data available via Working Lands for Wildfire (www.wlfw.org) and Rangeland Analysis Platform (https://rangelands.app/rap/

Citation: Rheinhardt Scholtz, Daniel R. Uden, Brady W. Allred, Victoria M. Donovan, Jeremy D. Maestas, Scott L. Morford, Matthew O. Jones, David E. Naugle, Samantha M. Cady, Dillon T. Fogarty, Alexander L. Metcalf, Brian Chaffin, Craig Allen, Caleb Roberts, Emily Rowen, Gwendwr Meredith, Holly K. Nesbitt, Matthew A. Williamson, Sabrina Gulab, Samantha Hamlin, Sapana Lohani, Dirac Twidwell, “Reconciling scale using the Resist-Accept-Direct (RAD) Framework to improve management of woody encroachment in grasslands,” Journal of Environmental Management, Volume 387, 2025, 125820, ISSN 0301-4797.

Permanent URL: https://doi.org/10.1016/j.jenvman.2025.125820