Disturbance history modulates how litter and herbaceous cover influence conifer regeneration after fire
Climate-driven increases in disturbance frequency and extent augment the potential for compounded disturbances. Drawing on well-studied forests that experienced successive disturbances, we asked: (1) how does post-fire cover of litter, herbaceous cover and bare ground vary between stands affected by combinations of blow-down, insect outbreak, and fire? (2) How do post-fire relationships between ground cover and conifer regeneration vary with recent disturbance history? We measured ground cover and conifer regeneration from 2003 to 2014 following stand-replacing fires in 2002. Burned stands were either blown down in 1997, affected by a 1940s Dendroctonus rufipennis (spruce beetle; SB) outbreak, or neither. Implementing mixed-effects models, we measured the relationships between pre-fire stand attributes (structural stage, canopy dominance and combination of disturbances) and post-fire ground cover and between post-fire ground cover and conifer regeneration. Fire-only stands had more litter and herbaceous cover post fire than other stands (P < 0.05). Fir regeneration increased with litter in stands that only burned, but decreased with litter in stands that were first blown down. Similarly, pine and fir regeneration increased with herbaceous cover after fire-only, but did the opposite in stands affected by the SB outbreak. Pre-fire legacies can modulate the effects of ground cover on plant regeneration.
International Journal of Wildland Fire
Gill, Nathan S.; Jarvis, Daniel; Rogan, John; and Kulakowski, Dominik, "Disturbance history modulates how litter and herbaceous cover influence conifer regeneration after fire" (2020). Geography. 266.