Interaction of historical and nonhistorical disturbances maintains native plant communities
Citation
Kirk W Davies, Jonathan D Bates, and Anthony J Svejcar, Interaction of historical and nonhistorical disturbances maintains native plant communities: .
Summary
Historical disturbance regimes are often considered a critical element in maintaining native plant communities. However, the response of plant communities to disturbance may be fundamentally altered as a consequence of invasive plants, climate change, or prior disturbances. The appropriateness of historical disturbance patterns under modern conditions and the interactions among disturbances are issues that ecologists must address to protect and restore native plant communities. We evaluated the response of Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh plant communities to their historical disturbance regime compared to other disturbance regimes. The historical disturbance regime of these plant communities was [...]
Summary
Historical disturbance regimes are often considered a critical element
in maintaining native plant communities. However, the response of plant
communities to disturbance may be fundamentally altered as a consequence
of invasive plants, climate change, or prior disturbances. The
appropriateness of historical disturbance patterns under modern
conditions and the interactions among disturbances are issues that
ecologists must address to protect and restore native plant communities.
We evaluated the response of Artemisia tridentata ssp. wyomingensis
(Beetle & A. Young) S.L. Welsh plant communities to their historical
disturbance regime compared to other disturbance regimes. The historical
disturbance regime of these plant communities was periodic fires with
minimal grazing by large herbivores. We also investigated the influence
of prior disturbance (grazing) on the response of these communities to
subsequent disturbance (burning). Treatments were: (1) ungrazed
(livestock grazing excluded since 1936) and unburned, (2) grazed and
unburned, (3) ungrazed and burned (burned in 1993), and (4) grazed and
burned. The ungrazed–burned treatment emulated the
historical disturbance regime. Vegetation cover, density, and biomass
production were measured the 12th, 13th, and 14th year post-burning.
Prior to burning the presence of Bromus tectorum L., an exotic annual
grass, was minimal (<0.5% cover), and vegetation characteristics were
similar between grazed and ungrazed treatments. However, litter
accumulation was almost twofold greater in ungrazed than in grazed
treatments. Long-term grazing exclusion followed by burning resulted in
a substantial B. tectorum invasion, but burning the grazed areas did not
produce an invasion. The ungrazed–burned treatment
also had less perennial vegetation than other treatments. The
accumulation of litter (fuel) in ungrazed treatments may have resulted
in greater fire-induced mortality of perennial vegetation in ungrazed
compared to grazed treatments. Our results demonstrate that prior
disturbances exert a strong influence on the response of plant
communities to subsequent disturbances and suggest that low-severity
disturbances may be needed in some plant communities to increase their
resilience to more severe disturbances. Modern deviations from
historical conditions can alter ecosystem response to disturbances, thus
restoring the historical disturbance regime may not be an appropriate
strategy for all ecosystems. Published in Ecological Applications,
volume 19, issue 6, on pages 1536 - 1545, in 2009.
