@article {KNZ001185,
	title = {Defoliation synchronizes above-ground growth of co-occurring C4 grass species},
	journal = {Ecology},
	volume = {89},
	year = {2008},
	pages = {2860 -2867},
	abstract = {<p>The aboveground net primary productivity (ANPP) of grass communities in grasslands and savannas is primarily determined by precipitation quantity. Recent research, motivated by predictions of changes in the distribution of rainfall events by global climate change models, indicates that ANPP may be affected by rainfall distribution as much as by annual totals. Grazing and community composition are also known to affect grassland ANPP. The manner in which interactions between rainfall distribution, grazing, and community composition affect the relationship between precipitation and ANPP represents a critical knowledge gap. The effects of community composition and grazing on aboveground growth responses to intraseasonal variation in water availability were investigated at seven grassland sites with a nonselective clipping experiment. The aboveground growth of the dominant C4 species at each site was measured at regular intervals for 2\&ndash;3 growing seasons in the presence or absence of regular defoliation. In the absence of defoliation, there was a general lack of synchrony of intraseasonal growth among co-occurring species. Variation in growth rates was high and was only partially explained by variation in rainfall. Regular defoliation increased growth synchrony at all sites, but changes in growth responses to rainfall varied between sites. These results suggest that community composition will be important in determining ANPP\&ndash;precipitation relationships under conditions of altered rainfall distribution. However this effect appears to be a result of species responding differently to soil water or other resources rather than to rainfall per se. Grazing may override the effects of community composition by reducing differences in growth patterns between species and has the potential to weaken precipitation controls on ANPP.</p>},
	keywords = {LTER-KNZ},
	doi = {10.1890/07-1434.1},
	url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/07-1434.1},
	author = {Swemmer, A.M. and Alan K. Knapp}
}
@phdthesis {KNZ001121,
	title = {The effect of intra-seasonal variation in precipitation on the productivity of grasses and grasslands},
	volume = {PhD Dissertation},
	year = {2007},
	pages = {1 -173},
	school = {Colorado State University},
	type = {Ph.D. Thesis},
	address = {Fort Collins, CO},
	keywords = {LTER-KNZ},
	url = {https://search.proquest.com/docview/304859815/?pq-origsite=primo},
	author = {Swemmer, A.M.}
}
@article {KNZ001122,
	title = {Intra-seasonal precipitation patterns and aboveground productivity in three perennial grasslands},
	journal = {Journal of Ecology},
	volume = {95},
	year = {2007},
	pages = {780 -788},
	abstract = {1 Relationships between above-ground net primary productivity (ANPP) of grasslands and annual precipitation are often weak at the site level, with much of the inter-annual variation in ANPP left unexplained. A potential reason for this is that the distribution of precipitation within a growing season affects productivity in addition to the total amount.
2 We analysed long-term ANPP data for three southern African temperate grasslands (mean annual precipitation ranging from 538 mm to 798 mm) to determine the effects of precipitation event size, number and spacing relative to seasonal totals.
3 Ungrazed, non-manipulated treatments at each site showed contrasting results despite sharing a common, dominant species. At the driest site, a model combining average event size and number of events per growing season provided a substantially better fit to the ANPP data than precipitation amount (seasonal total). At the wettest site, the interval between events was the most important precipitation variable. Precipitation distribution was not important at the intermediate site where amount was the best predictor of ANPP. A limit to the size of precipitation events efficiently utilized for ANPP was evident for the driest site only.
4 At each site, experimental treatments that altered species composition and soil fertility had little effect on precipitation{\textendash}ANPP relationships. The lack of consistency in the relative importance of the precipitation variables among sites suggests that local, edaphic factors modify precipitation{\textendash}ANPP relationships.
5 This analysis demonstrates that the distribution and size of precipitation events can affect ANPP independent of precipitation amount. As altered precipitation regimes are forecast by global climate models, the sensitivity of ecosystems to precipitation distribution should be considered when predicting responses to climate change.
6 While mean values of precipitation, and other ecosystem drivers, are typically used to predict function at the level of whole ecosystems, our results show that more complex measures of environmental variability may be required to understand ecosystem function, and to increase the accuracy of predictions of ecosystem responses to global change.},
	keywords = {LTER-KNZ},
	doi = {10.1111/j.1365-2745.2007.01237.x},
	author = {Swemmer, A.M. and Alan K. Knapp and Snyman, H.A.}
}
@article {KNZ001070,
	title = {Growth responses of twodominant C4 grass species to altered water availability},
	journal = {InternationalJournal of Plant Sciences},
	volume = {167},
	year = {2006},
	pages = {1001 -1010},
	abstract = {Identifying key ecophysiological traits that differ among dominant plant species and can be linked to species-specific responses to drought would improve our ability to forecast community and ecosystem responses to global climate change. The mesic grasslands of the central plains of North America are dominated by two C4 grass species, Andropogon gerardii and Sorghastrum nutans, which purportedly differ in their tolerance of water stress. Individuals of these two species were grown in the field under rain-out shelters and subjected to wet (watered every 2{\textendash}3 d) or dry (repeatedly subjected to wilting before watering) soil moisture regimes. A range of ecophysiological traits potentially important for tolerating water stress were concurrently measured. Although few traits differed between the species in the wet treatment, several traits were identified in the dry treatment that may enable A. gerardii to better tolerate drought. These were greater allocation to roots, reduced allocation to flowering, more rapid leaf turnover, and more rapid recovery of photosynthesis after wilting. The latter two traits may be particularly important for coping with increased variability in rainfall regimes in the future and are consistent with recently documented responses of A. gerardii to experimental increases in soil moisture variability.},
	keywords = {LTER-KNZ, Andropogon gerardii, biomass allocation, Climate change, leaf turnover, photosynthesis, Sorghastrum nutans, water stress},
	doi = {10.1086/505611},
	author = {Swemmer, A.M. and Alan K. Knapp and M.D. Smith}
}
