@article {49860,
	title = {Ecosystem resilience despite large-scale altered hydroclimatic conditions},
	journal = {Nature},
	volume = {494},
	year = {2013},
	month = {2013},
	pages = {349-352},
	chapter = {349},
	abstract = {<p class="rtejustify">Climate change is predicted to increase both drought frequency and duration, and when coupled with substantial warming, will establish a new hydroclimatological model for many regions1. Largescale, warm droughts have recently occurred in North America, Africa, Europe, Amazonia and Australia, resulting in major effects on terrestrial ecosystems, carbon balance and food security2,3. Here we compare the functional response of above-ground net primary production to contrasting hydroclimatic periods in the late twentieth century (1975{\textendash}1998), and drier, warmer conditions in the early twenty-first century (2000{\textendash}2009) in the Northern and Southern Hemispheres. We find a common ecosystem water-use efficiency (WUEe: above-ground net primary production/evapotranspiration) across biomes ranging from grassland to forest that indicates an intrinsic system sensitivity to water availability across rainfall regimes, regardless of hydroclimatic conditions. We found higher WUEe in drier years that increased significantly with drought to a maximum WUEe across all biomes; and a minimum native state in wetter years that was common across hydroclimatic periods. This indicates biome-scale resilience to the interannual variability associated with the early twenty-first century drought{\textemdash}that is, the capacity to tolerate low, annual precipitation and to respond to subsequent periods of favourable water balance. These findings provide a conceptual model of ecosystem properties at the decadal scale applicable to the widespread altered hydroclimatic conditions that are predicted for later this century. Understanding the hydroclimatic threshold that will break down ecosystem resilience and alter maximum WUEe may allow us to predict land-surface consequences as large regions become more arid, starting with waterlimited, low-productivity grasslands.</p>
},
	keywords = {aboveground net primary production, air temperature, ANPP, climate change, drought, ecosystem resilience, evapotranspiration, hydroclimate, MODIS, plant production, precipitation},
	doi = {10.1038/nature11836},
	url = {/files/bibliography/13-022.pdf},
	author = {Guillermo E. Ponce-Campos and S. Moran and Alfredo Huete and Yongguang Zhang and Bresloff, Cynthia and T. Huxman and Eamus, Derek and David D. Bosch and Anthony R. Buda and Stacey A. Gunter and Scalley, Tamara Heartsill and S.G. Kitchen and M.P. McClaran and McNab, W. Henry and Montoya, Diane S. and Jack A. Morgan and Debra C. Peters and John Sadler and M. S. Seyfried and Paul F. Starrs}
}
@article {49862,
	title = {Precipitation legacies in desert grassland primary production occur through previous-year tiller density},
	journal = {Ecology},
	volume = {94},
	year = {2013},
	month = {04/2013},
	pages = {435-443},
	chapter = {435},
	abstract = {In arid ecosystems, current-year precipitation often explains only a small proportion of annual aboveground net primary production (ANPP). We hypothesized that lags in the response of ecosystems to changes in water availability explain this low explanatory power, and that lags result from legacies from transitions from dry to wet years or the reverse. We explored five hypotheses regarding the magnitude of legacies, two possible mechanisms, and the differential effect of previous dry or wet years on the legacy magnitude. We used a three-year manipulative experiment with five levels of rainfall in the first two years (-80\% and -50\% reduced annual precipitation (PPT), ambient, +50\% and +80\% increased PPT), and reversed treatments in year 3. Legacies of previous two years, which were dry or wet, accounted for a large fraction (20\%) of interannual variability in production on year 3. Legacies in ANPP were similar in absolute value for both types of precipitation transitions, and their magnitude was a function of the difference between previous and current-year precipitation. Tiller density accounted for 40\% of legacy variability, while nitrogen and carryover water availability showed no effect. Understanding responses to changes in interannual precipitation will assist in assessing ecosystem responses to climate change-induced increases in precipitation variability.},
	keywords = {aboveground net primary production, ANPP, black grama, Bouteloua eriopoda, Chihuahuan Desert, desert grasslands, mesquite, precipitation legacies, prosopis glandulosa, rainfall manipulation, tiller dynamics},
	doi = {10.1890/12-1237.1},
	url = {/files/bibliography/13-017.pdf},
	author = {Lara Reichmann and O. E. Sala and Debra C. Peters}
}
@article {49915,
	title = {Spatiotemporal patterns of production can be used to detect state change across an arid landscape},
	journal = {Ecosystems},
	volume = {15},
	year = {2012},
	month = {01/2012},
	pages = {34-47},
	chapter = {34},
	abstract = {Methods to detect and quantify shifts in the state of ecosystems are increasingly important as global change drivers push more systems towards thresholds of change. Temporal relationships between precipitation and aboveground net primary production (ANPP) have been studied extensively in arid and semiarid ecosystems, but rarely has spatial variation in these relationships been investigated at a landscape scale, and rarely has such information been viewed as a resource for mapping the distribution of different ecological states. We examined the broad-scale effects of a shift from grassland to shrubland states on spatiotemporal patterns of remotely sensed ANPP proxies in the northern Chihuahuan Desert. We found that the Normalized Difference Vegetation Index (NDVI), when averaged across an eight-year period, did not vary significantly between these states, despite changes in ecosystem attributes likely to influence water availability to plants. In contrast, temporal relationships between precipitation and time-integrated NDVI (NDVI-I) modeled on a per-pixel basis were sensitive to spatial variation in shrub canopy cover, a key attribute differentiating ecological states in the region. The slope of the relationship between annual NDVI-I and two year cumulative precipitation was negatively related to, and accounted for 71\% of variation in, shrub canopy cover estimated at validation sites using high spatial resolution satellite imagery. These results suggest that remote sensing studies of temporal precipitation-NDVI relationships may be useful for deriving shrub canopy cover estimates in the region, as well as for mapping other ecological state changes characterized by shifts in long-term ANPP, plant functional type dominance, or both.},
	keywords = {aboveground net primary production, Chihuahuan Desert state change, grassland, normalized difference vegetation index, precipitation, remote sensing, shrub encroachment, shrubland},
	doi = {10.1007/s10021-011-9490-2},
	url = {/files/bibliography/12-003.pdf},
	author = {Jebediah C. Williamson and Brandon T Bestelmeyer and Debra C. Peters}
}
@article {50230,
	title = {Shrub encroachment in North American grasslands: Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs},
	journal = {Global Change Biology},
	volume = {14},
	year = {2008},
	month = {January 30, 2008},
	pages = {615-623},
	publisher = {Blackwell Publishing},
	abstract = {<p>Shrub encroachment into grass-dominated biomes is occurring globally due to a variety of anthropogenic activities, but the consequences for carbon (C) inputs, storage and cycling remain unclear. We studied eight North American graminoid-dominated ecosystems invaded by shrubs, from arctic tundra to Atlantic coastal dunes, to quantify patterns and controls of C inputs via aboveground net primary production (ANPP). Across a 4-fold range in mean annual precipitation (MAP), a key regulator of ecosystem C input at the continental scale, shrub invasion decreased ANPP in xeric sites, but dramatically increased ANPP (\&gt;1000 g/m2) at high MAP, where shrub patches maintained extraordinarily high leaf area. Concurrently, the relationship between MAP and ANPP shifted from being non-linear in grasslands to linear in shrublands. Thus, relatively abrupt (\&lt;50 yrs) shifts in growth form dominance, without changes in resource quantity, can fundamentally alter continental-scale pattern of C inputs and control by MAP in ways that exceed the direct effects of climate change alone.</p>
},
	keywords = {aboveground net primary production, carbon, climate change, encroachment, grass-dominated biomes, grasslands, growth form, LAI, MAP, North American, shrub, shrublands},
	doi = {10.1111/j.1365-2486.2007.01512.x },
	url = {/files/bibliography/08-005.pdf},
	author = {A. K. Knapp and J. M. Briggs and S.L. Collins and Steven R. Archer and M.S. Bret-Harte and Ewers, B. and Debra C. Peters and Young, D. and Shaver, G. and Cleary, M.B.}
}
