Oak decline in the Boston Mountains, Arkansas, USA: spatial and temporal patterns under two fire regimes. (Special Issue: Forest landscape modeling - approaches and applications.)

摘要

A spatially explicit forest succession and disturbance model was used to delineate the extent and dispersion of oak decline under two fire regimes over a 150-year period. The objectives of this study were to delineate potential current and future oak decline areas using species composition and age structure data in combination with ecological land types, and to investigate how relatively frequent simulated fires and fire suppression affect the dynamics of oak decline. We parameterized LANDIS, a spatially explicit forest succession and disturbance model, for areas in the Boston Mountains of Arkansas, USA. Land type distribution and initial species/age class were parameterized into LANDIS using existing forest data. Tree species were parameterized as five functional groups including white oak (Quercus alba, Q. stellata and Q. muehlenbergii), red oak (Q. rubra, Q. marilandica, Q. falcata and Q. coccinea), black oak (Q. velutina), shortleaf pine (Pinus echinata), and maple (Acer rubrum and A. saccharum) groups. Two fire regimes were also parameterized: current fire regime with a fire return interval of 300 years and a historic fire regime with an overall average fire return interval of 50 years. The 150-year simulation suggests that white oak and shortleaf pine abundance would increase under the historic fire regime and that the red oak group abundance increases under the current fire regime. The black oak group also showed a strong increasing trend under the current fire regime, and only the maple group remained relatively unchanged under both scenarios. At present, 45% of the sites in the study area are classified as potential oak decline sites (sites where red and black oak are >70 years old). After 150 simulation years, 30% of the sites were classified as potential oak decline sites under the current fire regime, whereas 20% of the sites were potential oak decline sites under the historic fire regime. This analysis delineated potential oak decline sites and established risk ratings for these areas. This is a further step toward precision management and planning.