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Summary: After clearcutting xerothermic oakwoods once natural in semiarid temperate loess regions of Hungary the perennial understorey grass Brachypodium pinnatum (L.) Beauv. may persist through decades and often dominates grasslands maintained by grazing and/or cutting in the place of former oakwoods. This grass also successfully establishes from low- to high-light microenvironments co-ocurring as forest regeneration commences after pasture abandonment. It was assumed that B. pinnatum must possess a high degree of phenotypic plasticity for such an ecological versatility. This assumption was tested by comparing leaf and shoot morphology and leaf photochemistry in the species’ three typical microenvironments (full shade under oak canopy, half shade near shrubs, and full sun in unshaded grassland) for plants growing in situ and for those reciprocally transplanted between these microhabitats. Aboveground standing crop of B. pinnatum was greatest near shrubs, indicating that in this microhabitat light limitation (typical in oak shade) and water stress (appearing temporarily in the grassland) are ameliorated. Average leaf lifespan was greatest under oak canopy, while leaf senescence was highest in the grassland. An efficient adjustment to low light was observed both in leaf morphology (specific leaf mass, leaf thickness and bulk tissue density were lowest in oak shade) and in leaf photochemistry (quantum yield of PSII (ΦPSII), photochemical quenching (qP), and non-photochemical energy dissipation (NPQ) were lower, while PSII antenna efficiency (Fv’/Fm’) was higher for leaves in oak shade than for others). Transplanted plants showed remarkable phenotypic plasticity since after one year of transfer their leaves did not differ in photochemistry and/or morphology from those growing in situ in the new microenvironment. However, transplants appeared to be more sensitive to the high radiation load in the grassland than in situ ones. Our results confirm the high capacity of B. pinnatum for phenotypical adjustment to habitat light environment, that is consistent with the species’ original forest-steppe coenological affinity and also may contribute to the species’ persistence after deforestation. Nevertheless, temporary water stress associated with high radiation load in the unshaded grassland appear to pose a limitation on the ecological distribution of this species in Central Europe. [Copyright &y& Elsevier]

• Transgenerational effects of drought were found for a subordinate annual grass. • Transgenerational effects of drought changed from negative to positive with age. • Drought in the maternal environment reduced the early growth of offspring. • Drought in the maternal environment increased the adult shoot biomass of offspring. • Drought in the maternal environment increased the seed production of offspring. Drought can induce shifts in plant species or functional group abundances, which may favor coexisting subordinate species at the expense of previous dominants. Within-generation and transgenerational phenotypic plasticity can be important mechanisms to shape species responses to drought. Although a handful of studies have already investigated transgenerational plasticity in the context of drought, they provided variable results, and usually focused on species that currently dominate communities. We performed pot experiments with Secale sylvestre , a typical subordinate species in semiarid grasslands of Central Hungary. We tested if this annual grass shows reduced growth or reproduction in response to drought, and whether drought in the maternal environment affects offspring performance. For both maternal and offspring generations, plant height, shoot biomass, flowering onset, and seed number showed no within-generation plasticity in response to drought, and drought only decreased the seed mass of mother plants. In contrast, we found strong transgenerational effects on the overall performance of progenies, which changed with offspring age. At an early life stage, shoots were shorter for the offspring of drought-treated mothers than for the progenies of control mothers. This difference turned in the opposite direction later, and tiller number was also greater for the offspring of drought-treated mothers. Furthermore, the offspring of drought-treated mothers had over two-times higher adult shoot biomass and seed production compared to the offspring of control mothers. These beneficial transgenerational effects may help S. sylvestre to gain dominance in sand grasslands following dry years that decrease the abundance of perennial grasses, a vegetation change often observed in these grasslands after droughts. Our study provides the first evidence for positive transgenerational plasticity in response to drought for a subordinate species, which may be adaptive when the suppression of dominant species in the offspring environment is predictable from drought in the maternal environment. [ABSTRACT FROM AUTHOR]