Exotic plant species impact belowground processes by influencing resource availability through enhanced microbial activity as a consequence of litter inputs. We have little understanding of the impact of microbe-driven nutrient fluctuations on biomass accumulation of invasive species. In a recent article in AoB PLANTS, Bajpai and Inderjit attempt to determine whether soil community-driven nitrogen availability influences invader biomass. They discovered that soil communities cultured by Ageratina adenophora, a neotropical invader in Asia, retain available nitrogen that influences the biomass of the invader. Through soil manipulation experiments they found that A. adenophora grows better in soil with higher available nitrogen content. Ageratina adenophora-invaded soil had higher microbial activity and available nitrogen due to higher inputs of terpene-rich litter compared to soil not yet invaded by it. Their results provide evidence that microbe-linked nitrogen availability exerts a positive impact on A. adenophora biomass accumulation, emphasizing the importance of soil community-driven nitrogen availability in invasion success.
The potential risks of genetically modified crops must be identified before their commercialization. In this context, several studies have reported the transfer of transgenes from transgenic rice to red rice weed. However, gene flow also occurs in the opposite direction, resulting in transgenic seeds that have incorporated the traits of wild red rice. In a new study in AoB PLANTS, Serrat et al. found that this reverse flow was higher than direct gene flow, but that transgenic seeds carrying wild genes remained in the spike and were thus mostly removed at harvesting. Nevertheless, this phenomenon must be considered in fields used for elite seed production and in developing countries where there is a risk of increasing GM red rice weed infestation.
Trinidad’s Aripo Savanna is a rare example of an intact tropical grassland. It is a living laboratory in which to explore the mechanisms used by plants to survive the stress of life in the full glare of the equatorial sun. In a new study in AoB PLANTS, John-Bejai et al. found that the dominant species, Lagenocarpus rigidus, avoids overheating not through higher transpiration or more reflective leaf surfaces (as expected), but by altering the size and shape of its leaves to suit each location. This plasticity in leaf morphology is combined with plasticity in cell membrane properties, which allows the leaves to tolerate periods of extreme heat. In the absence of these traits a closely related species Lagenocarpus guianensis, finds its range restricted to the shaded savanna edges where heat and light are less overbearing. The results highlight the importance of trait-plasticity to the survival of plants in the face of climate change.
How plants manage their water use in seasonally dry environments is a major component of each individual species’ ecology. In a new study in AoB PLANTS, Brodribb et al. examine closely related species of a highly successful Australian conifer genus, Callitris, to determine whether species growing under contrasting climates show adaptive specialization in the way they use water. Sampling four Callitris species growing across a large climatic range, they found that each exhibited a similar strategy of linking growth very tightly with rainfall events, and surviving dry periods by resisting damage to their water transport system. This strategy is similar to the Junipers of the Northern Hemisphere, and requires a cavitation-resistant xylem.
Biological invasions pose serious threats to biodiversity and ecosystem services worldwide. While the effects of invasive species are well-documented, less is known about which specific plant traits convey “invasiveness”, because most studies compare closely related but different species, which can confound results. A review of the literature by Mozdzer et al. in AoB PLANTS compared the genetic lineages of members of the same species (Phragmites australis), specifically those native to North America and a lineage introduced from Europe, in an attempt to address this complex issue. The authors found that the ability to change both physiologically and morphologically were the key to success of the introduced genetic lineage under current and predicted global change conditions.
Plants link above- and belowground subsystems, and a recent study in AoB PLANTS suggests that their phylogenetic relationships leave a “fingerprint” on belowground communities. Gorman et al. found that after correcting for evolutionary history, tree species identity influenced belowground arthropod communities through plant functional traits. These data suggest that plant species structure may be an important predictor in shaping associated soil arthropod communities and further suggest the importance of better understanding the extended consequences of evolutionary history for ecological processes, as similarity in traits may not always reflect similar ecology.
In the study of geographic range boundary development, the focus has been on leading rather than on trailing edge dynamics. This is an important caveat as trailing edge dynamics will be critical for understanding population level persistence. A study in AoB PLANTS by Alsdurf et al. begins to fill this knowledge gap and extends the conceptual framework of the field by focusing on trans-generational environmental effects in Boechera stricta, a perennial wild relative of Arabidopsis. The authors found that while these effects may overcome some constraints on stress tolerance evolution and range expansion, other constraints may be created to limit range.
Soil seed banks serve as reservoirs for future plant communities, and when diverse and abundant can buffer vegetation communities against environmental fluctuations. Sparse seed banks, however, may lead to future declines of already rare species. Seed banks in wetland communities are often robust and can persist over long time periods, making wetlands model systems for studying the spatial and temporal links between above- and belowground communities. In a recent study in AoB PLANTS, Faist et al. found that the belowground community in the soil seed bank of restored ephemeral wetlands (vernal pools) in California’s Central Valley, USA, has been less invaded by exotic plants and is a reservoir for rare and native plant species. They also found that seed bank community structure most closely resembled the aboveground community structure from five to eight years prior to seed bank sampling rather than more recent years. The maintenance of rare and native plant species in soil seed banks, even while aboveground vegetation communities are being invaded by exotic plants, is an exciting finding with important implications for management and restoration efforts in annual plant communities.
The transition of a breeding system from outcrossing to selfing has been considered to be a widespread evolutionary trend in flowering plants, allowing species to colonize new habitats after long-distance dispersal. Moreover, Darwin realized that autonomous self-pollination could be an adaptation to reproduction if pollinator services were lost or extremely unpredictable. In a recent study published in AoB PLANTS, Xiong et al. tested a hypothesis that the persistence of Himalayan mayapple (Podophyllum hexandrum), an early spring flowering herb in the Himalayan region, is attributable to the transition from self-incompatibility to self-compatibility i.e. the capacity for selfing in an unpredictable pollination environment. To clarify whether automatic self-pollination is achieved by movement of the pistil as suggested in a previous study, they measured incline angles of the pistil and observed flower movement during anthesis. They found that automatic self-pollination was facilitated by petals closing and stamens moving simultaneously to contact the stigma. A scarcity of pollinators may have driven the shift to delayed selfing in Podophyllum hexandrum.
In a novel analysis by Gornish published in AoB PLANTS, a regression-design life-table response experiment was used to determine how the interaction of fire and density affected vital rates of the perennial composite Pityopsis aspera, and ultimately how these changes in vital rates contributed to differences in estimated population growth rates. The shape of the relationship between population growth rate (λ) and density was modified by fire, primarily as a result of contributions from adult flowering stasis and survival, and first-year survival probabilities. Fire modified and even reversed the effect of extreme densities on adult flowering stasis and survival and of first-year survival, resulting in more positive contributions from these transitions to λ at the lowest and highest density values. These results demonstrate the first application of a regression-design life-table response experiment to elucidating the interactive effects of density and fire. They highlight the utility of this approach for both capturing the complex dynamics of populations and establishing a means of determining how vital rates might contribute to differences in demography across densities.