Phragmites australis is a cosmopolitan grass and often the dominant species in the ecosystems it inhabits. Due to high intraspecific diversity and phenotypic plasticity, P. australis has an extensive ecological amplitude and a great capacity to acclimate to adverse environmental conditions; it can therefore offer valuable insights into plant responses to global change. Here we review the ecology and ecophysiology of prominent P. australis lineages and their responses to multiple forms of global change. Key findings of our review are that: (1) P. australis lineages are well-adapted to regions of their phylogeographic origin and therefore respond differently to changes in climatic conditions such as temperature or atmospheric CO2; (2) each lineage consists of populations that may occur in geographically different habitats and contain multiple genotypes; (3) the phenotypic plasticity of functional and fitness-related traits of a genotype determine the responses to global change factors; (4) genotypes with high plasticity to environmental drivers may acclimate or even vastly expand their ranges, genotypes of medium plasticity must acclimate or experience range-shifts, and those with low plasticity may face local extinction; (5) responses to ancillary types of global change, like shifting levels of soil salinity, flooding, and drought, are not consistent within lineages and depend on adaptation of individual genotypes. These patterns suggest that the diverse lineages of P. australis will undergo intense selective pressure in the face of global change such that the distributions and interactions of co-occurring lineages, as well as those of genotypes within-lineages, are very likely to be altered. We propose that the strong latitudinal clines within and between P. australis lineages can be a useful tool for predicting plant responses to climate change in general and present a conceptual framework for using P. australis lineages to predict plant responses to global change and its consequences.

The primary productivity of coastal wetlands is changing dramatically in response to rising atmospheric carbon dioxide (CO 2 ) concentrations, nitrogen (N) enrichment, and invasions by novel species, potentially altering their ecosystem services and resilience to sea level rise. In order to determine how these interacting global change factors will affect coastal wetland productivity, we quantified growing-season carbon assimilation (≈gross primary productivity, or GPP) and carbon retained in living plant biomass (≈net primary productivity, or NPP) of North American mid-Atlantic saltmarshes invaded by Phragmites australis (common reed) under four treatment conditions: two levels of CO 2 (ambient and +300 ppm) crossed with two levels of N (0 and 25 g N added m −2 yr −1 ). For GPP, we combined descriptions of canopy structure and leaf-level photosynthesis in a simulation model, using empirical data from an open-top chamber field study. Under ambient CO 2 and low N loading (i.e., the Control), we determined GPP to be 1.66±0.05 kg C m −2 yr −1 at a typical Phragmites stand density. Individually, elevated CO 2 and N enrichment increased GPP by 44 and 60%, respectively. Changes under N enrichment came largely from stimulation to carbon assimilation early and late in the growing season, while changes from CO 2 came from stimulation during the early and mid-growing season. In combination, elevated CO 2 and N enrichment increased GPP by 95% over the Control, yielding 3.24±0.08 kg C m −2 yr −1 . We used biomass data to calculate NPP, and determined that it represented 44%-60% of GPP, with global change conditions decreasing carbon retention compared to the Control. Our results indicate that Phragmites invasions in eutrophied saltmarshes are driven, in part, by extended phenology yielding 3.1× greater NPP than native marsh. Further, we can expect elevated CO 2 to amplify Phragmites productivity throughout the growing season, with potential implications including accelerated spread and greater carbon storage belowground.

Solar photovoltaic (PV) technology is being deployed at an unprecedented rate. However, utility-scale solar energy development is land intensive and its largescale installation can have negative impacts on the environment. In particular, solar energy infrastructure can require extensive landscape modification that transforms soil ecological functions, thereby impacting hydrologic, vegetative, and carbon dynamics. However, reintroducing native vegetation to solar PV sites may be a means of restoring their soils. To this end, we investigated critical soil physical and chemical parameters at a revegetated photovoltaic array and an adjacent reference grassland in Colorado, United States. Seven years after revegetation, we found that carbon and nitrogen remained lower in the PV soil than in the reference soil and contained a greater fraction of coarse particles. We also found that the PV modules introduced heterogeneity in the soil moisture distribution, with precipitation accumulating along the lower edges of panels. The redistribution of soil moisture by panel arrays could potentially be used in concert with planting strategies to maximize plant growth or minimize soil erosion, and should be considered when evaluating the potential to co-locate vegetation with solar infrastructure.

Despite the importance of fine roots for the acquisition of soil resources such as nitrogen and water, the study of linkages between traits and both population and community dynamics remains focused on aboveground traits. We address this gap by investigating associations between belowground traits and metrics of species dynamics. Our analysis included 85 species from a long‐term data set on the transition from old field to forest in eastern North America (the Buell‐Small Succession Study) and the new Fine‐Root Ecology Database. Given the prominent roles of life form (woody vs. non‐woody) and species origin (native vs. exotic) in defining functional relationships, we also assessed whether traits or their relationships with species dynamics differed for these groups. Species that reached their peak abundance early in succession had fine‐root traits corresponding to resource acquisitive strategies (i.e., they were thinner, less dense, and had higher nitrogen concentrations) while species that peaked progressively later had increasingly conservative strategies. In addition to having more acquisitive root traits than native species, exotics diverged from the above successional trend, having consistently thinner fine roots regardless of the community context. Species with more acquisitive fine‐root morphologies typically had faster rates of abundance increase and achieved their maximal rates in fewer years. Decreasing soil nutrient availability and increasing belowground competition may become increasingly strong filters in successional communities, acting on root traits to promote a transition from acquisitive to conservative foraging. However, disturbances that increase light and soil resource availability at local scales may allow acquisitive species, especially invasive exotics, to continue colonizing late into the community transition to forest.