Trading water for carbon in the future: Effects of elevated CO2 and warming on leaf hydraulic traits in a semiarid grassland.

The effects of climate change on plants and ecosystems are mediated by plant hydraulic traits, including interspecific and intraspecific variability of trait phenotypes. Yet, integrative and realistic studies of hydraulic traits and climate change are rare. In a semiarid grassland, we assessed the response of several plant hydraulic traits to elevated CO2 (+200 ppm) and warming (+1.5 to 3°C; day to night). For leaves of five dominant species (three graminoids and two forbs), and in replicated plots exposed to 7 years of elevated CO2 , warming, or ambient climate, we measured: stomatal density and size, xylem vessel size, turgor loss point, and water potential (pre-dawn). Interspecific differences in hydraulic traits were larger than intraspecific shifts induced by elevated CO2 and/or warming. Effects of elevated CO2 were greater than effects of warming, and interactions between treatments were weak or not detected. The forbs showed little phenotypic plasticity. The graminoids had leaf water potentials and turgor loss points that were 10% to 50% less negative under elevated CO2 ; thus, climate change might cause these species to adjust their drought resistance strategy away from tolerance and toward avoidance. The C4 grass also reduced allocation of leaf area to stomata under elevated CO2 , which helps explain observations of higher soil moisture. The shifts in hydraulic traits under elevated CO2 were not, however, simply due to higher soil moisture. Integration of our results with others' indicates that common species in this grassland are more likely to adjust stomatal aperture in response to near-term climate change, rather than anatomical traits; this contrasts with apparent effects of changing CO2 on plant anatomy over evolutionary time. Future studies should assess how plant responses to drought may be constrained by the apparent shift from tolerance (via low turgor loss point) to avoidance (via stomatal regulation and/or access to deeper soil moisture).

Genetic and functional variation across regional and local scales is associated with climate in a foundational prairie grass.

Global change forecasts in ecosystems require knowledge of within-species diversity, particularly of dominant species within communities. We assessed site-level diversity and capacity for adaptation in Bouteloua gracilis, the dominant species in the Central US shortgrass steppe biome. We quantified genetic diversity from 17 sites across regional scales, north to south from New Mexico to South Dakota, and local scales in northern Colorado. We also quantified phenotype and plasticity within and among sites and determined the extent to which phenotypic diversity in B. gracilis was correlated with climate. Genome sequencing indicated pronounced population structure at the regional scale, and local differences indicated that gene flow and/or dispersal may also be limited. Within a common environment, we found evidence of genetic divergence in biomass-related phenotypes, plasticity, and phenotypic variance, indicating functional divergence and different adaptive potential. Phenotypes were differentiated according to climate, chiefly median Palmer Hydrological Drought Index and other aridity metrics. Our results indicate conclusive differences in genetic variation, phenotype, and plasticity in this species and suggest a mechanism explaining variation in shortgrass steppe community responses to global change. This analysis of B. gracilis intraspecific diversity across spatial scales will improve conservation and management of the shortgrass steppe ecosystem in the future.

Intraoperative radiation therapy as part of planned monotherapy for early-stage breast cancer.

INTRODUCTION: Adjuvant whole breast radiation therapy has developed into the standard of care for patients following a lumpectomy for early-stage breast cancer. However, there is recent interest in intraoperative radiation therapy (IORT) to minimize toxicity while still improving local control beyond surgical resection and anti-estrogen therapy alone. MATERIALS AND METHODS: All patients were evaluated pre-operatively in a multidisciplinary clinic setting at a community hospital for suitability for breast conservation therapy. A total of 109 patients were reviewed receiving 110 IORT treatments. Patients were followed with clinical breast examinations and mammography as clinically indicated. RESULTS: At a median follow-up of 29.9 months, 2/110 (1.8%) patients experienced a local failure. One patient (0.9%) experienced a regional failure. Local control, disease-free survival and overall survival at 3 years were 98.9% (95%CI 92.2-99.8), 97.2% (95%CI 88.9-99.3), and 96.0% (95%CI 84.9-99.0), respectively. Five-year local control, disease-free survival, and overall survival rates were 96.3% (95%CI 84.7-99.2), 94.6% (95%CI 83.2-98.3), and 92.5% (95%CI 80.4-97.3), respectively. Patient self-reported cosmetic outcome was available for 51 patients, with all patients reporting being either very pleased, pleased, or satisfied with their cosmetic outcome, and no patients reported being dissatisfied or worse. CONCLUSIONS: The results of our series suggest the feasibility of utilizing IORT in a community-based cancer center with a high degree of local control, and patient satisfaction with regard to cosmesis. While the results of this series suggest that IORT may be a promising modality, longer follow-up is warranted to better understand exactly which clinicopathological features can predict long-term locoregional disease control.