@article {KNZ001689,
	title = {Global environmental change and the nature of aboveground net primary productivity responses: insights from long-term experiments},
	journal = {Oecologia},
	volume = {177},
	year = {2015},
	month = {Jan-04-2015},
	pages = {935 - 947},
	abstract = {<p>Many global change drivers chronically alter resource availability in terrestrial ecosystems. Such resource alterations are known to affect aboveground net primary production (ANPP) in the short term; however, it is unknown if patterns of response change through time. We examined the magnitude, direction, and pattern of ANPP responses to a wide range of global change drivers by compiling 73 datasets from long-term (\&gt;5 years) experiments that varied by ecosystem type, length of manipulation, and the type of manipulation. Chronic resource alterations resulted in a significant change in ANPP irrespective of ecosystem type, the length of the experiment, and the resource manipulated. However, the pattern of ecosystem response over time varied with ecosystem type and manipulation length. Continuous directional responses were the most common pattern observed in herbaceous-dominated ecosystems. Continuous directional responses also were frequently observed in longer-term experiments (\&gt;11 years) and were, in some cases, accompanied by large shifts in community composition. In contrast, stepped responses were common in forests and other ecosystems (salt marshes and dry valleys) and with nutrient manipulations. Our results suggest that the response of ANPP to chronic resource manipulations can be quite variable; however, responses persist once they occur, as few transient responses were observed. Shifts in plant community composition over time could be important determinants of patterns of terrestrial ecosystem sensitivity, but comparative, long-term studies are required to understand how and why ecosystems differ in their sensitivity to chronic resource alterations.</p>},
	keywords = {LTER-KNZ, Aboveground productivity, Hierarchical response framework (HRF), Long-Term Ecological Research (LTER) Network, Nutrient addition, Precipitation manipulation},
	issn = {0029-8549},
	doi = {10.1007/s00442-015-3230-9},
	url = {https://link.springer.com/article/10.1007\%2Fs00442-015-3230-9},
	author = {M.D. Smith and Kimberly J. La Pierre and Scott. L. Collins and Alan K. Knapp and Gross, K.L. and Barrett, J.E. and Frey, S.D. and Gough, L. and Miller, R.J. and Morris, J.T. and Rustad, L.E. and Yarie, J.}
}
@article {KNZ00841,
	title = {Influence of climate variability on plant production and N-mineralization in Central US grasslands},
	journal = {Journal of Vegetation Science},
	volume = {13},
	year = {2002},
	pages = {383 -394},
	abstract = {We assessed the influence of annual and seasonal climate variability over soil organic matter (SOM), above-ground net primary production (ANPP) and in situ net nitrogen (N) mineralization in a regional field study across the International Geosphere Biosphere Programme (IGBP) North American mid-latitude transect (Koch et al. 1995). We hypothesized that while trends in SOM are strongly correlated with mean climatic parameters, ANPP and net N-mineralization are more strongly influenced by annual and seasonal climate because they are dynamic processes sensitive to short-term variation in temperature and water availability. Seasonal and monthly deviations from long-term climatic means, particularly precipitation, were greatest at the semi-arid end of the transect. ANPP is sensitive to this climatic variability, but is also strongly correlated with mean annual climate parameters. In situ net N-mineralization and nitrification were weakly influenced by soil water content and temperature during the incubation and were less sensitive to seasonal climatic variables than ANPP, probably because microbial transformations of N in the soil are mediated over even finer temporal scales. We found no relationship between ANPP and in situ net N-mineralization. These results suggests that methods used to estimate in situ net N-mineralization are inadequate to represent N-availability across gradients where microbial biomass, N-immobilization or competition among plants and microbes vary.},
	keywords = {LTER-KNZ, Annual variation, ANPP, Central Grasslands region, Environmental gradient, IGBP Transect, Mineralization, Nitrogen flux, Seasonal variation},
	doi = {10.1111/j.1654-1103.2002.tb02062.x},
	author = {Barrett, J.E. and McCulley, R.L. and Lane, D.R. and Burke, I.C. and Lauenroth, W.K.}
}
