Summer dormancy, drought survival and functional resource acquisition strategies in California perennial grasses

Abstract

Both the escape and acquisitive springtime strategies observed in summer dormant perennial taxa are typically associated with annual grasses. California grasslands were once dominated by perennial species, but have been overtaken by non-native Mediterranean annual grasses, which are expected to be further favoured by climate change. Owing to functional similarity with these exotic annuals, it is suggested that native summer dormant taxa may play an important ecological role in the future of both natural and restored California grasslands.

Implications of plant functional traits and drought survival strategies for ecological restoration

“…This suggests higher growth potential is associated with more efficient competition for light and shallow soil moisture, but relatively lower investment in storage to survive severe drought. Our study also supports previous work finding more tolerant, summer dormant California perennial grass species flowered earlier and had faster springtime leaf elongation (Balachowski, Bristiel, & Volaire, 2016), likely because summer drought constrains the window for reproductive growth in Mediterranean-type climates (Thompson, 2005).…”

“…Volaire, unpubl. data), and tolerance in the Sierra population is within the high‐range of other California species (Balachowski et al., ). Additionally, variation was not significant at 9.2% SWC, highlighting the importance of experimental dehydration to very low, discriminative thresholds in drought‐adapted taxa.…”

The genetic architecture of shoot and root trait divergence between upland and lowland ecotypes of a perennial grass

“…These factors combined may indicate that hallii employs a fast acquisitive strategy for drought escape; acquiring nutrients rapidly and flowering quickly to enter a dormant state before periods of summer drought. Acquisitive shoot and root strategies have been associated with fast growth strategies and summer dormancy in other perennial grasses (Balachowski et al , 2016). This contrasts with the lower SLA, and RMR of the lowland filipes , which may employ a slow strategy of thicker longer lasting leaves, larger more persistent roots, and abundant above ground foliage.…”

Aboveground Biomass Dynamics in the Low-Mountain Dry Grasslands of the Tianshan Mountains

“…In contrast, plants began to wilt during this stage in 2017. Because the temperature was very high and the SVWC was relatively low during this stage in 2017, plants entered dormancy earlier (Table 1 and Figure 1a) [12]. From 11 July to 10 August, inter-annual variation in AB was similar to that of precipitation (Table 1).…”

“…In addition to phenology, low SVWC was the most important factor that led to low AB in this region [11]. In summer, plants enter dormancy, due to high air temperature and low SVWC (Table 1 and Figures 1 and 2) [12]. Based on the observations, dormancy generally occurred when the 0 -40 cm SVWC was below 15% in summer, which mainly occurred in August (Figure 1a and Table 1).…”