@article {51207, title = {Disturbance intensity and above- and belowground herbivory effects on long-term (14 y) recovery of a semiarid grassland}, journal = {Plant Ecology}, volume = {139}, number = {2}, year = {1998}, month = {December 1, 1998}, pages = {221-233}, abstract = {

The importance of disturbance intensity and herbivory by cattle and white grubs, or the larvae of June beetles (including Phyllophaga fimbripes), to recovery of shortgrass steppe ecosystems in Colorado, U.S.A. were evaluated over a fourteen year time period. Disturbance intensity was defined by survival of the dominant grass species (Bouteloua gracilis) after an outbreak of root feeding activity by white grubs. Sixteen patches of vegetation consisting of four pairs of adjacent ungrazed-grazed by cattle locations with two replicates that were recently affected by white grubs were selected in 1977. Disturbance intensity was determined in 1977 by the area in each patch that contained live tillers of B. gracilis. Permanent plots were located both within and outside of each patch. Plant basal cover and density by species were estimated at time of peak aboveground biomass in six different years on each plot.

}, keywords = {Bouteloua gracilis, cattle grazing, june beetle larvae, root feeders, shortgrass steppe, succession}, doi = {10.1023/A:1009789017151}, url = {/files/bibliography/606.pdf}, author = {D.P. Coffin and Laycock, W.A. and W. K. Lauenroth} } @conference {51208, title = {Lagtimes in shifts of ecosystem boundaries in response to climate change: Importance of plant recruitment and soil development constraints}, booktitle = {83rd Annual Meeting, Ecological Society of America}, volume = {79}, year = {1998}, month = {1998}, pages = {45}, abstract = {Ecosystem boundaries and geographic distributions of species are predicted to change in response to directional changes in climate. The ability of a species to shift its geographic distribution depends upon processes associated with the recruitment, growth, and mortality of plants. Because these processes are nonlinearly related to climate and are also affected by soil processes, lag times in responses may result. Recent climate change simulation analyses predict an expansion of Chihuahuan desert grasslands and a reduction of shrublands in the southwestern U.S. Our objective was to evaluate the importance of plant life history traits and soil development processes to responses of important species in these ecosystems. We used a spatially-interactive gap dynamics model to predict responses for three conditions of initial soil development, from organic matter-rich soils to highly degraded soils. Predicted response times ranged from decades to millenia, and increased as soil development state decreased. Plant life history traits were the most important constraint on soils with high organic matter content. Although directional climate change may shift species distributions, these shifts will not occur rapidly or uniformly across a landscape or region, and will depend upon interactions between plant and soil processes.}, author = {D.P. Coffin and Jeffrey E. Herrick} } @article {JRN54833, title = {Transient responses of North-American grasslands to changes in climate}, journal = {Climate Change}, volume = {34}, year = {1996}, month = {10/01/1996}, pages = {269-278}, chapter = {269}, abstract = {

Our objective was to evaluate the transient responses of grasslands in the central grassland region of North America to changes in climate. We used an individual plant-based gap dynamics simulation model (STEPPE-GP) linked with a soil water model (SOILWAT) to evaluate the effects of changes in climate on the composition and structure of grassland vegetation. Five functional types of plants were simulated based upon lifeform, physiology, and rooting distribution with depth. C3 and C4 perennial grasses with either a shallow or deep rooting distribution, and deeply rooted C3 shrubs were simulated under current climatic conditions and under a GFDL climate change scenario for nine sites representative of the temperature and precipitation regimes in the grassland region.

Although vegetation at the sites responded differently to climate change, shifts in functional types occurred within 40 years of the start of the climate change. C4 grasses increased in dominance or importance at all sites with a change in climate, primarily as a result of increases in temperature in all months at all sites. The coolest sites that arc currently dominated by C3 grasses were predicted to shift to a dominance by C4 grasses, whereas sites that are currently dominated by C4 grasses had an increase in importance of this functional type with a change in climate. Current annual temperature was the best predictor of changes in C3 biomass, and C3 and C4 biomass combined; current annual precipitation was the best predictor of changes in C4 biomass. These predicted shifts in dominance and importance of C3versus C4 grasses would have important implications for the management of natural grasslands as well as the cultivation of crops in the central grassland region.

}, keywords = {changes in climate, North-American grasslands, Transient responses}, url = {https://link.springer.com/article/10.1007/BF00224638}, author = {D.P. Coffin and W. K. Lauenroth} }