Generalized and specific state-and-transition models to guide management and restoration of Caldenal forests

Authors: PEINETTI, H. RAUL - University Of La Pampa; Bestelmeyer, Brandon; CHIRINO, CLAUDIA - University Of La Pampa; KIN, ALICIA - University Of La Pampa; FRANK BUSS, MARIA ELISA FRA - University Of La Pampa

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2018
Publication Date: 3/5/2019
Citation: Peinetti, H., Bestelmeyer, B.T., Chirino, C., Kin, A., Frank Buss, M. 2019. Generalized and specific state-and-transition models to guide management and restoration of Caldenal forests. Rangeland Ecology and Management. 72:230-236. https://doi.org/10.1016/j.rama.2018.11.002.
DOI: https://doi.org/10.1016/j.rama.2018.11.002

Interpretive Summary: Management impacts and natural events can produce ecosystem state changes that are difficult to reverse. The Caldenal ecoregion in central Argentina has undergone widespread state change and restoration is urgently needed, but as yet there has been no knowledge synthesis to support restoration actions. We used a state-and-transition model format to synthesize the causes of state change in the Caldenal and identify potential restoration approaches. The introduction of livestock in the Caldenal favors the dispersal and establishment of woody plants and causes a shift from a fire-proof open two-layer forest to a fire-loving three-layer closed forest. The closed forest eventually transitions to a shrub thicket state with repeated fire (i.e., thicketization). Controlled, low intensity fire can be used to build the resilience of an open forest state. Strategic fire can eliminate accumulated grass biomass and promote short grass species, which reduces the risk of a wildfire event. Restoring open forest states from shrub thicket states will require a large-scale selective thinning and pruning operation. Wildfires may create a restoration opportunity in dense shrub thickets by facilitating the labor required to remove woody plants and opening the space for planting native Prosopis spp. trees. Long-term restoration requires breaking the positive livestock-thicketization-fire feedback mechanism to ensure the persistence of a restored open forest state.

Technical Abstract: Management impacts and natural events can produce ecosystem state changes that are difficult to reverse. In such cases, a detailed understanding of drivers, thresholds, and feedback mechanisms are needed to design restoration interventions. The Caldenal ecoregion in central Argentina has undergone widespread state change and restoration is urgently needed, but as yet there has been no knowledge synthesis to support restoration actions. We used a state-and-transition model format to synthesize the causes of state change in the Caldenal and identify potential restoration approaches. The introduction of livestock in the Caldenal favors the dispersal and establishment of woody plants and causes a shift from a pyrophobic open two-layer forest to a pyrophytic three-layer closed forest. The closed forest eventually transitions to a shrub thicket state with repeated fire (i.e., thicketization). Controlled, low intensity fire can be used to build the resilience of an open forest state. Strategic fire can eliminate accumulated grass biomass and promote short grass species, which reduces the risk of a wildfire event. Restoring open forest states from shrub thicket states will require a large-scale selective thinning and pruning operation. Wildfires may create a restoration opportunity in dense shrub thickets by facilitating the labor required to remove woody plants and opening the space for planting native Prosopis spp. trees. Long-term restoration requires breaking the positive livestock-thicketization-fire feedback mechanism to ensure the persistence of a restored open forest state.