TY - JOUR T1 - Drought-mediated stem and belowground bud dynamics in restored grasslands JF - Applied Vegetation Science Y1 - 2012 A1 - Carter, D.L. A1 - Vanderweide, B. A1 - John M. Blair KW - Below-ground KW - Climate change KW - Community KW - forb KW - grass KW - Lag KW - Meristem KW - plant KW - prairie KW - Rainfall manipulation AB -

Question Does the below-ground bud bank mediate response to drought in restored grasslands? Location Platte River Valley region of south-central Nebraska, USA. Methods We imposed severe drought for one growing season using rainfall manipulation structures and measured the response of above- and below-ground plant communities (ramet and below-ground bud densities) with respect to non-drought controls during the drought year and a recovery year. Results Drought reduced below-ground bud bank density and above-ground stem density. However, bud bank density recovered, and bud production was higher on previously droughted subplots relative to controls in the year following drought. The response of below-ground bud and above-ground stem density to drought differed according to functional identity (C3 grass, C4 grass, and forb), with forbs least resistant to, but having the greatest recovery from, drought. Conclusions While overall density in restored grasslands was resilient, drought effects on below-ground bud banks may have longer-term impacts on plant community structure. Reduced density above- or below-ground during the growing season following drought may allow for the persistence of species relatively more reliant on recruitment from seed banks in favourable micro-sites.

VL - 15 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1654-109X.2012.01200.x ER - TY - JOUR T1 - Fire resistance of tree species explains gallery forest community composition JF - Forest Ecology and Management Y1 - 2011 A1 - Vanderweide, B. A1 - D.C. Hartnett KW - Bark KW - Fire resistance KW - Forest composition KW - gallery forest KW - Konza Prairie AB -

Fire, climatic variability, and grazing by large herbivores have historically limited woody vegetation in the tallgrass prairie region of North America to gallery forests in protected areas along rivers and streams. Fire, in particular, has been a strong selective pressure against woody vegetation. Consequently, we expect that dominant tree species in these forests have developed mechanisms for tolerating periodic surface fires. Susceptibility of trees to fire damage depends in part on key properties of bark which influence heat transfer to the vascular cambium, including thickness, density, and moisture content. An historical (1983) survey of Konza Prairie Biological Station in northeast Kansas, USA indicated that gallery forests were co-dominated by Quercus macrocarpa and Quercus muehlenbergii, while Celtis occidentalis occurred as an important sub-dominant species. Populus deltoides, Gleditsia triacanthos, and Juniperus virginiana were relatively uncommon. To test the hypothesis that historically dominant gallery forest tree species are more resistant to fire damage than uncommon species, fire was applied to the bark of 10 individuals of each of these six species under conditions mimicking surface fires (400 °C for 120 s). Maximum temperature at the vascular cambium, bark thickness, bark moisture content, and bark density were measured. Trees were considered fire-resistant if the vascular cambium temperature remained below the thermal cell death threshold, 60 °C, throughout the treatment. Using logistic regression, bark thickness was found to be a significant predictor of lethal cambium temperatures (P = 0.002), while neither bark density nor moisture content were significantly related to lethal cambium temperature (P = 0.279 and P = 0.131, respectively). Across species, a minimum bark thickness of approximately 8.6 mm was necessary to maintain the vascular cambium temperature below 60 °C. Trees that produce thick bark quickly in juvenile size classes (P. deltoides, Q. macrocarpa, and Q. muehlenbergii) experienced lower temperatures at the vascular cambium than those which do not develop thick bark with increasing diameter (C. occidentalis, G. triacanthos, and J. virginiana). Ranking these tree species by either the DBH or age needed to develop the minimum protective bark thickness largely agreed with ranking based on historical relative importance. As fire frequency and intensity decrease in remnant tallgrass prairie of North America as a result of habitat fragmentation, fire suppression, and changing land management, fire-sensitive species may increase in relative importance in gallery forests because of increased juvenile survival.

VL - 261 UR - https://www.sciencedirect.com/science/article/pii/S0378112711000764?via%3Dihub ER -