02217nas a2200169 4500008004100000245012400041210006900165300001600234490000800250520162300258100001701881700002001898700001501918700001801933700002301951856007301974 2017 eng d00aAssessing the roles of fire frequency and precipitation in determining woody plant expansion in central U.S. grasslands0 aAssessing the roles of fire frequency and precipitation in deter a2683–26980 v1223 a
Woody plant expansion into grasslands and savannas is occurring and accelerating worldwide and often impacts ecosystem processes. Understanding and predicting the environmental and ecological impacts of encroachment has led to a variety of methodologies for assessing its onset, transition, and stability, generally relying on dynamical systems approaches. Here we continue this general line of investigation to facilitate the understanding of the roles of precipitation frequency and intensity and fire frequency on the conversion of grasslands to woody-dominated systems focusing on the central United States. A low-dimensional model with stochastic precipitation and fire disturbance is introduced to examine the complex interactions between precipitation and fire as mechanisms that may suppress or facilitate increases in woody cover. By using Lyapunov exponents, we are able to ascertain the relative control exerted on woody encroachment through these mechanisms. Our results indicate that precipitation frequency is a more important control on woody encroachment than the intensity of individual precipitation events. Fire, however, exerts a much more dominant impact on the limitation of encroachment over the range of precipitation variability considered here. These results indicate that fire management may be an effective strategy to slow the onset of woody species into grasslands. While climate change might predict a reduced potential for woody encroachment in the near future, these results indicate a reduction in woody fraction may be unlikely when considering anthropogenic fire suppression.
1 aBrunsell, N.1 avan Vleck, E.S.1 aNosshi, M.1 aRatajczak, Z.1 aNippert, Jesse, B. uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017JG004046