ARIMA-based forecasting of the effects of wildfire on the increasing tree cover trend and recurrence interval of woody encroachment in grazing land

Abstract

Invasive tree removal from grazing lands using costly brush management practices is widely employed. However, wildfire-like natural events can prevent the increasing trend of woody tree encroachment in grazing lands at no cost, instead of cost-oriented prescribed burning. This study aims to estimate the effects of wildfire in 2002 on woody tree encroachment trends during the post-wildfire period (2003–20), as well as the recurrence interval of the encroachment of a wildfire site in the United States. An autoregressive integrated moving average (ARIMA) model was employed to forecast the tree cover during the post-wildfire period. We found that the pre-wildfire tree cover was 4.26% of the total area, which decreased to 1.42% immediately after the wildfire. During 2003–20, wildfire contributed to an average lowering of woody-dominated areas of the wildfire site by 6.59%. The wildfire-recovered grazing area was converted to a woody area again after 8 years, which was due to recurring woody encroachment. Therefore, it is critical to implement brush management strategies to stop the recurrence of woody plant encroachment following wildfire.