@article {KNZ001497,
	title = {Incorporating clonal growth form clarifies the role of plant height in response to nitrogen addition},
	journal = {Oecologia},
	volume = {169},
	year = {2012},
	pages = {1053 -1062},
	abstract = {<p>Nutrient addition to grasslands consistently causes species richness declines and productivity increases. Competition, particularly for light, is often assumed to produce this result. Using a long-term dataset from North American herbaceous plant communities, we tested whether height and clonal growth form together predict responses to fertilization because neither trait alone predicted species loss in a previous analysis. Species with a tall-runner growth form commonly increased in relative abundance in response to added nitrogen, while short species and those with a tall-clumped clonal growth form often decreased. The ability to increase in size via vegetative spread across space, while simultaneously occupying the canopy, conferred competitive advantage, although typically only the abundance of a single species within each height-clonal growth form significantly responded to fertilization in each experiment. Classifying species on the basis of two traits (height and clonal growth form) increases our ability to predict species responses to fertilization compared to either trait alone in predominantly herbaceous plant communities.</p>},
	keywords = {LTER-KNZ, Clonal growth, Competition, grassland, Nitrogen addition, productivity},
	doi = {10.1007/s00442-012-2264-5},
	url = {https://link.springer.com/article/10.1007\%2Fs00442-012-2264-5},
	author = {Gough, L. and Gross, K.L. and Cleland, E.E. and Clark, C.M. and Scott. L. Collins and Fargione, J.E. and Pennings, S.C. and K.N. Suding}
}
@article {KNZ001452,
	title = {Patterns of trait convergence and divergence among native and exotic species in herbaceous plant communities are not modified by nitrogen enrichment},
	journal = {Journal of Ecology},
	volume = {99},
	year = {2011},
	pages = {1327 -1338},
	keywords = {LTER-KNZ},
	doi = {10.1111/j.1365-2745.2011.01860.x},
	url = {https://www.jstor.org/stable/41333056?seq=1$\#$page_scan_tab_contents},
	author = {Cleland, E.E. and Clark, C.M. and Scott. L. Collins and Fargione, J.E. and Gough, L. and Gross, K.L. and Pennings, S.C. and K.N. Suding}
}
@article {KNZ001181,
	title = {Rank clocks and plant community dynamics},
	journal = {Ecology},
	volume = {89},
	year = {2008},
	pages = {3534 -3541},
	abstract = {Summarizing complex temporal dynamics in communities is difficult to achieve in a way that yields an intuitive picture of change. Rank clocks and rank abundance statistics provide a graphical and analytical framework for displaying and quantifying community dynamics. We used rank clocks, in which the rank order abundance for each species is plotted over time in temporal clockwise direction, to display temporal changes in species abundances and richness. We used mean rank shift and proportional species persistence to quantify changes in community structure in long-term data sets from fertilized and control plots in a late successional old field, frequently and infrequently burned tallgrass prairie, and Chihuahuan desert grassland and shrubland communities. Rank clocks showed that relatively constant species richness masks considerable temporal dynamics in relative species abundances. In the old field, fertilized plots initially experienced high mean rank shifts that stabilized rapidly below that of unfertilized plots. Rank shifts were higher in infrequently burned vs. annually burned tallgrass prairie and in desert grassland compared to shrubland vegetation. Proportional persistence showed that arid grasslands were more dynamic than mesic grasslands. We conclude that rank clocks and rank abundance statistics provide important insights into community dynamics that are often hidden by traditional univariate approaches.},
	keywords = {LTER-KNZ},
	doi = {10.1890/07-1646.1},
	author = {Scott. L. Collins and K.N. Suding and Cleland, E.E. and Batty, M. and Pennings, S.C. and Gross, K.L. and Grace, J.S. and Gough, L. and Fargione, J.E. and Clark, C.M.}
}
@article {KNZ001226,
	title = {Scale-dependent responses of plant biodiversity to nitrogen enrichment},
	journal = {Ecology},
	volume = {89},
	year = {2008},
	pages = {2165 -2171},
	abstract = {Experimental studies demonstrating that nitrogen (N) enrichment reduces plant diversity within individual plots have led to the conclusion that anthropogenic N enrichment is a threat to global biodiversity. These conclusions overlook the influence of spatial scale, however, as N enrichment may alter β diversity (i.e., how similar plots are in their species composition), which would likely alter the degree to which N-induced changes in diversity within localities translate to changes in diversity at larger scales that are relevant to policy and management. Currently, it is unclear how N enrichment affects biodiversity at scales larger than a small plot. We synthesized data from 18 N-enrichment experiments across North America to examine the effects of N enrichment on plant species diversity at three spatial scales: small (within plots), intermediate (among plots), and large (within and among plots). We found that N enrichment reduced plant diversity within plots by an average of 25\% (ranging from a reduction of 61\% to an increase of 5\%) and frequently enhanced β diversity. The extent to which N enrichment altered β diversity, however, varied substantially among sites (from a 22\% increase to an 18\% reduction) and was contingent on site productivity. Specifically, N enrichment enhanced β diversity at low-productivity sites but reduced β diversity at high-productivity sites. N-induced changes in β diversity generally reduced the extent of species loss at larger scales to an average of 22\% (ranging from a reduction of 54\% to an increase of 18\%). Our results demonstrate that N enrichment often reduces biodiversity at both local and regional scales, but that a focus on the effects of N enrichment on biodiversity at small spatial scales may often overestimate (and sometimes underestimate) declines in regional biodiversity by failing to recognize the effects of N on β diversity.},
	keywords = {LTER-KNZ},
	doi = {10.1890/07-0971.1},
	author = {Chalcraft, D.R. and Cox, S.B. and Clark, C.M. and E.E Cleland and K.N. Suding and Weiher, E. and Pennington, D.}
}
@article {KNZ001180,
	title = {Species responses to nitrogen fertilization in herbaceous plant communities, and associated species traits},
	journal = {Ecology},
	volume = {89},
	year = {2008},
	pages = {1175 -},
	abstract = {<p>This synthetic data set contains plant species relative abundance measures from 35 nitrogen (N) fertilization experiments conducted at 10 sites across North America. The data set encompasses the fertilization responses of 575 taxa from 1159 experimental plots. The methodology varied among experiments, in particular with regard to the type and amount of N added, plot size, species composition measure (biomass harvest, pin count, or percent cover), additional experimental manipulations, and experimental duration. At each site, each species has been classified according to a number of easily identified categorical functional traits, including life history, life form, the number of cotyledons, height relative to the canopy, potential for clonal growth, and nativity to the United States. Additional data are available for many sites, indicated by references to publications and web sites. Analyses of these data have shown that N enrichment significantly alters community composition in ways that are predictable on the basis of plant functional traits as well as environmental context. This data set could be used to answer a variety of questions about how plant community composition and structure respond to environmental changes.</p>},
	keywords = {LTER-KNZ},
	doi = {10.1890/07-1104.1},
	url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/07-1104.1},
	author = {Cleland, E.E. and Clark, C.M. and Scott. L. Collins and Fargione, J.E. and Gough, L. and Gross, K.L. and Pennings, S.C. and W.D. Bowman and Robertson, G.P. and Simpson, J. and Tilman, D. and K.N. Suding}
}
@article {KNZ001094,
	title = {Environmental and plant community determinants ofspecies loss following nitrogen enrichment},
	journal = {Ecology Letters},
	volume = {10},
	year = {2007},
	pages = {596 -607},
	abstract = {Global energy use and food production have increased nitrogen inputs to ecosystems worldwide, impacting plant community diversity, composition, and function. Previous studies show considerable variation across terrestrial herbaceous ecosystems in the magnitude of species loss following nitrogen (N) enrichment. What controls this variation remains unknown. We present results from 23 N-addition experiments across North America, representing a range of climatic, soil and plant community properties, to determine conditions that lead to greater diversity decline. Species loss in these communities ranged from 0 to 65\% of control richness. Using hierarchical structural equation modelling, we found greater species loss in communities with a lower soil cation exchange capacity, colder regional temperature, and larger production increase following N addition, independent of initial species richness, plant productivity, and the relative abundance of most plant functional groups. Our results indicate sensitivity to N addition is co-determined by environmental conditions and production responsiveness, which overwhelm the effects of initial community structure and composition.},
	keywords = {LTER-KNZ},
	doi = {10.1111/j.1461-0248.2007.01053.x},
	author = {Clark, C.M. and Cleland, E.E. and Scott. L. Collins and Fargione, J.E. and Gough, L. and Pennings, S.C. and K.N. Suding and Grace, J.B.}
}
@article {KNZ00977,
	title = {Do individual plant speciesshow predictable responses to nitrogen addition across multipleexperiments?},
	journal = {Oikos},
	volume = {110},
	year = {2005},
	pages = {547 -555},
	abstract = {A number of experiments have addressed how increases in nitrogen availability increase the productivity and decrease the diversity of plant communities. We lack, however, a rigorous mechanistic understanding of how changes in abundance of particular species combine to produce changes in community productivity and diversity. Single experiments cannot provide insight into this issue because each species occurs only once per experiment, and each experiment is conducted in only one location; thus, it is impossible from single experiments to determine whether responses of particular species are consistent across environments or dependent on the particular environmental context in which the experiment was conducted. To address this issue, we assembled a dataset of 20 herbaceous species that were each represented in at least 6 different fertilization experiments and tested whether responses were general across experiments. Of the 20 species, one consistently increased in relative abundance and five consistently decreased across replicate experiments. A partially-overlapping group of 8 species displayed responses to nitrogen that varied predictably among experiments as a function of geographic location, neighboring species, or a handful of other community characteristics (ANPP, precipitation, species richness, relative abundance of focal species in control plots, and community composition). Thus, despite modest replication and a limited number of predictor variables, we were able to identify consistent patterns in response of 10 out of 20 species across multiple experiments. We conclude that the responses of individual species to nitrogen addition are often predictable, but that in most cases these responses are functions of the abiotic or biotic environment. Thus, a rigorous understanding of how plant species respond to nitrogen addition will have to consider not only the traits of individual plant species, but also aspects of the communities in which those plants live.},
	keywords = {LTER-KNZ},
	doi = {10.1111/j.0030-1299.2005.13792.x},
	author = {Pennings, S.C. and Clark, C.M. and Cleland, E.E. and Scott. L. Collins and Gough, L. and Gross, K.L. and Milchunas, D.G. and K.N. Suding}
}
@article {KNZ00967,
	title = {Functional and abundance based mechanisms explain diversity loss due to nitrogen fertilization},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {102},
	year = {2005},
	pages = {4387 -4392},
	abstract = {Human activities have increased N availability dramatically in terrestrial and aquatic ecosystems. Extensive research demonstrates that local plant species diversity generally declines in response to nutrient enrichment, yet the mechanisms for this decline remain unclear. Based on an analysis of >900 species responses from 34 N-fertilization experiments across nine terrestrial ecosystems in North America, we show that both trait-neutral and trait-based mechanisms operate simultaneously to influence diversity loss as production increases. Rare species were often lost because of soil fertilization, randomly with respect to traits. The risk of species loss due to fertilization ranged from >60\% for the rarest species to 10\% for the most abundant species. Perennials, species with N-fixing symbionts, and those of native origin also experienced increased risk of local extinction after fertilization, regardless of their initial abundance. Whereas abundance was consistently important across all systems, functional mechanisms were often system-dependent. As N availability continues to increase globally, management that focuses on locally susceptible functional groups and generally susceptible rare species will be essential to maintain biodiversity.},
	keywords = {LTER-KNZ},
	doi = {10.1073/pnas.0408648102},
	author = {K.N. Suding and Scott. L. Collins and Gough, L. and Clark, C.M. and Cleland, E.E. and Gross, K.L. and Milchunas, D.G. and Pennings, S.}
}
