Precipitation legacies in desert grassland primary production occur through previous‐year tiller density

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.

Enhanced precipitation variability decreases grass- and increases shrub-productivity

“…1). Results from the first 2 y, including a single transition for each treatment through years 2009 and 2010, agree with a previous experiment that showed that the negative effect of a previous-dry year on current-year ANPP was of the opposite sign but of the same magnitude as the positive effect of a previous-wet year on current-year ANPP (21). The effects of single dry-to-wet and wet-todry transitions cancelled each other and predicted null effects of interannual precipitation variation on average ANPP.…”

Spatio-Temporal Patterns and Climate Variables Controlling of Biomass Carbon Stock of Global Grassland Ecosystems from 1982 to 2006

“…In order to predict the response of grassland ecosystems to future climate change, we need to understand the effects of environmental factors on the spatial and temporal changes of grassland biomass carbon stock. However, large uncertainties still exist on the amounts, spatial and temporal variability, and driving forces of grassland biomass, especially at the global scale [8][9][10].…”

Habitat Effect on Allometry of a Xeric Shrub (Artemisia ordosica Krasch) in the Mu Us Desert of Northern China

“…Since shrub biomass accumulates over the course of several years, it shows a weak response to conditions of the present year (i.e., dry, normal, or wet) [23,46]. However, both a long-term (14 years) observational study [47] and a short-term (three years) rainfall manipulative experiment [48] also indicated that shrub ANPP showed low interannual variation and was only weakly dependent on annual precipitation. Poor response of shrub growth to precipitation could occur largely because the deep roots of these plants are able to utilize water from deep soil layers [49,50].…”