Precipitation and environmental constraints on three aspects of flowering in three dominant tallgrass species

Abstract

Summary Flower production can comprise up to 70% of above‐ground primary production in grasslands. Yet we know relatively little about how the environment and timing of rainfall determine flower productivity. Evidence suggests that deficits or additions of rainfall during phenlologically relevant periods (i.e. growth, storage, initiation of flowering and reproduction) can determine flower production in grasslands. We used long‐term data from the Konza Prairie LTER to test how fire, soil topography and precipitation amounts during four phenologically relevant periods of the growing season constrain three aspects of flowering in three dominant C4 grass species. Specifically, we examined the probability of flowering, flowering stalk density and individual flowering stalk biomass for Andropogon gerardii, Schizachyrium scoparium and Sorghastrum nutans. We found that each of the three species responded to the amount of precipitation during phenologically relevant periods in unique ways. All aspects of A. gerardii flowering were sensitive to precipitation during the flowering stalk elongation period (20 June – 3 August). The probability of S. nutans flowering was partly determined by precipitation during the rapid growth phase (21 April – 4 June), whereas flowering stalk density of this species depended on rainfall during flowering stalk elongation (20 June – 3 August). In contrast, all aspects of flowering of S. scoparium were relatively independent of rainfall during any period. Our results demonstrate that three functionally similar, co‐dominant C4 grass species respond differently to phenologically relevant precipitation periods. As a result, drought during any phenological window during the growing season can adversely impact biomass and flowering production of grasslands via species‐specific reductions in flowering stalk density and biomass. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12904/suppinfo is available for this article.

Local adaptation, genetic divergence, and experimental selection in a foundation grass across the US Great Plains’ climate gradient

“…Most growth, especially among dominant grasses, is clonal in these grassland communities (Knapp et al, ). Indeed, very little regeneration from seed occurs in prairies in general (Benson & Hartnett 2006; Lemoine, Dietrich, & Smith, ; Dalgleish et al, ) , including restored prairie (Willand, Baer, Gibson, & Klopf, ) unless disturbed (Weaver & Fitzpatrick, ). Furthermore, seedlings are rarely observed in the extremely competitive environment of the prairie, nor did we observe seedlings or recruitment into our plots in the six years of the experiment.…”

Precipitation amount and event size interact to reduce ecosystem functioning during dry years in a mesic grassland

“…Felton, personal observation). Flowering events, such as that in 2015, are highly variable from year to year at the Konza Prairie (Lemoine, Dietrich, & Smith, ), but are highly sensitive to water availability during stalk elongation in mid‐June (Dietrich & Smith, ). Despite this, the underlying RUE‐precipitation pattern was similar between years, and the same qualitative results were derived from analysing these two experimental gradients separately or combined (Figure S2).…”

Nonlinear drought plasticity reveals intraspecific diversity in a dominant grass species

“…The most substantial difference we detected during our recovery phase was a genotype disparity in flowering probability, from a 0.86 probability in G2 S to 0.11 in G5, which was inversely related to re‐sprouting probability. Flowering sensitivity of A. gerardii under drought (Dietrich & Smith, 2016; Lemoine et al., 2017) could therefore be driven disproportionately by a subset of genotypes.…”