Soil Development and Organic Carbon Stocks Across a Lithosequence in the Perhumid Coastal Temperate Rainforests of Southeast Alaska

The perhumid coastal temperate rainforests of southeast Alaska contain an abundance of soil organic carbon (SOC) that has accumulated in a wet, cool climate where forest fire disturbance is minimal and organic matter decomposition rates are low. Coastal temperate rainforests are supported by carbon-rich soils that provide ecosystem services including nutrient cycling, climate regulation, habitat and food for wildlife, salmon habitat, and recreation. The objective of our research was to examine how lithology and bioclimatic factors influence total SOC abundance, soil development, and carbon distribution with depth in upland soils formed in a coastal temperate rainforest environment. A lithosequence was established across 18 sites that encompassed three contrasting lithologies: slate, metavolcanics, and phyllite. Soils from the lithosequence were collected from mid-backslope positions on north and south facing hillslopes in the Tongass National Forest near Juneau, Alaska. Our approach combined field-based soil morphological descriptions with laboratory analyses to determine total carbon and nitrogen percent, soil pH, bulk density, and particle size distribution. SOC stocks, profile development indices (PDI), and the POD index were calculated for each soil profile sample analyzed in the study. Our study presents evidence for the formation of deep, fine to coarse-textured Spodosols on steep (31 to 80%) backslopes in frequently dissected, deeply and shallowly incised, smooth mountain slopes, broken mountain slopes, and hills. The soils contained a high percentage of coarse rock fragments (51.8% ± 20.4) with thin, broken E horizons and thick subsurface, spodic horizons. The soils are well-developed with PDIs ranging from 14.50 ± 6.62 to 26 ± 5.27 and POD index values spanning 8.25 ± 0.35 to 14.10 ± 18.80 across all sites. The PDI and POD indices did not significantly differ among the lithologies although we did observe that metavolcanics contained significantly more very fine sand compared to slate and phyllite. Slate contained significantly more very coarse sand compared to metavolcanics and phyllite. The accumulation of SOC was consistent across the three lithologies with averages of 182 ± 15.70 Mg ha-1 for slate, 181 ± 49 Mg ha-1 for metavolcanic, and 218 ± 124 Mg ha-1 for phyllite. However, we did find soils formed in slate has less variation in SOC (coefficient of variation (CV) of 9) compared to phyllite or metavolcanic (CV of 57 and 27, respectively). We found that the maximum clay and carbon values co-occurred in the uppermost Bh or Bhs horizons in 67% of the soil profiles studied. We also found that over 60% of SOC accumulated in the B horizons. We predict that well-developed soils and SOC accumulation resulted from coupled bioclimatic properties including the cool climate, abundant precipitation, and the organic inputs from acidic vegetation (i.e., forest floor debris, roots). We speculate that soil depth and physical disturbance events such as tree throw and colluvium deposition influences SOC stocks covariance suggesting total pedon depth and disturbance events influence SOC stock totals as well as variance. We emphasize the importance of including measures of deep soil C found in the spodic horizons when assessing SOC across landscapes to account for total SOC in temperate rainforest environments. Our work addressed a need to advance knowledge of how soils develop in steep, hilly, upland soils while also improving understanding of SOC distribution in understudied yet ecologically valued coastal rainforest systems

A coupled microscopy approach to assess the nano-landscape of weathering

Mineral weathering is a balanced interplay among physical, chemical, and biological processes. Fundamental knowledge gaps exist in characterizing the biogeochemical mechanisms that transform microbe-mineral interfaces at submicron scales, particularly in complex field systems. Our objective was to develop methods targeting the nanoscale by using high-resolution microscopy to assess biological and geochemical drivers of weathering in natural settings. Basalt, granite, and quartz (53-250 mu m) were deployed in surface soils (10 cm) of three ecosystems (semiarid, subhumid, humid) for one year. We successfully developed a reference grid method to analyze individual grains using: (1) helium ion microscopy to capture micron to sub-nanometer imagery of mineral-organic interactions; and (2) scanning electron microscopy to quantify elemental distribution on the same surfaces via element mapping and point analyses. We detected locations of biomechanical weathering, secondary mineral precipitation, biofilm formation, and grain coatings across the three contrasting climates. To our knowledge, this is the first time these coupled microscopy techniques were applied in the earth and ecosystem sciences to assess microbe-mineral interfaces and in situ biological contributors to incipient weathering.Oregon State University faculty startup fund; Office of Biological and Environmental Research; NSF [EAR-GEO-1331846, EAR-0724958, IOS-1354219]; [EAR-1023215]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

A coupled microscopy approach to assess the nano-landscape of weathering

Mineral weathering is a balanced interplay among physical, chemical, and biological processes. Fundamental knowledge gaps exist in characterizing the biogeochemical mechanisms that transform microbe-mineral interfaces at submicron scales, particularly in complex field systems. Our objective was to develop methods targeting the nanoscale by using high-resolution microscopy to assess biological and geochemical drivers of weathering in natural settings. Basalt, granite, and quartz (53-250 µm) were deployed in surface soils (10 cm) of three ecosystems (semiarid, subhumid, humid) for one year. We successfully developed a reference grid method to analyze individual grains using: (1) helium ion microscopy to capture micron to sub-nanometer imagery of mineral-organic interactions; and (2) scanning electron microscopy to quantify elemental distribution on the same surfaces via element mapping and point analyses. We detected locations of biomechanical weathering, secondary mineral precipitation, biofilm formation, and grain coatings across the three contrasting climates. To our knowledge, this is the first time these coupled microscopy techniques were applied in the earth and ecosystem sciences to assess microbe-mineral interfaces and in situ biological contributors to incipient weathering

Effect of Doxorubicin Plus Olaratumab vs Doxorubicin Plus Placebo on Survival in Patients With Advanced Soft Tissue Sarcomas The ANNOUNCE Randomized Clinical Trial

Importance: Patients with advanced soft tissue sarcoma (STS) have a median overall survival of less than 2 years. In a phase 2 study, an overall survival benefit in this population was observed with the addition of olaratumab to doxorubicin over doxorubicin alone. Objective: To determine the efficacy of doxorubicin plus olaratumab in patients with advanced/metastatic STS. Design, Setting, and Participants: ANNOUNCE was a confirmatory, phase 3, double-blind, randomized trial conducted at 110 sites in 25 countries from September 2015 to December 2018; the final date of follow-up was December 5, 2018. Eligible patients were anthracycline-naive adults with unresectable locally advanced or metastatic STS, an Eastern Cooperative Oncology Group performance status of 0 to 1, and cardiac ejection fraction of 50% or greater. Interventions: Patients were randomized 1:1 to receive doxorubicin, 75 mg/m2 (day 1), combined with olaratumab (n = 258), 20 mg/kg in cycle 1 and 15 mg/kg in subsequent cycles, or placebo (n = 251) on days 1 and 8 for up to 8 21-day cycles, followed by olaratumab/placebo monotherapy. Main Outcomes and Measures: Dual primary end points were overall survival with doxorubicin plus olaratumab vs doxorubicin plus placebo in total STS and leiomyosarcoma (LMS) populations. Results: Among the 509 patients randomized (mean age, 56.9 years; 58.2% women; 46.0% with LMS), all were included in the primary analysis and had a median length of follow-up of 31 months. No statistically significant difference in overall survival was observed between the doxorubicin plus olaratumab group vs the doxorubicin plus placebo group in either population (total STS: hazard ratio, 1.05 [95% CI, 0.84-1.30], P = .69, median overall survival, 20.4 months vs 19.7 months; LMS: hazard ratio, 0.95 [95% CI, 0.69-1.31], P = .76, median overall survival, 21.6 months vs 21.9 months). Adverse events of grade 3 or greater reported in 15% or more of total patients with STS were neutropenia (46.3% vs 49.0%), leukopenia (23.3% vs 23.7%), and febrile neutropenia (17.5% vs 16.5%). Conclusions and Relevance: In this phase 3 clinical trial of patients with advanced STS, treatment with doxorubicin plus olaratumab vs doxorubicin plus placebo resulted in no significant difference in overall survival. The findings did not confirm the overall survival benefit observed in the phase 2 trial. Trial Registration: ClinicalTrials.gov Identifier: NCT02451943.status: publishe

Effect of Doxorubicin Plus Olaratumab vs Doxorubicin Plus Placebo on Survival in Patients With Advanced Soft Tissue Sarcomas: The ANNOUNCE Randomized Clinical Trial.

Patients with advanced soft tissue sarcoma (STS) have a median overall survival of less than 2 years. In a phase 2 study, an overall survival benefit in this population was observed with the addition of olaratumab to doxorubicin over doxorubicin alone. To determine the efficacy of doxorubicin plus olaratumab in patients with advanced/metastatic STS. ANNOUNCE was a confirmatory, phase 3, double-blind, randomized trial conducted at 110 sites in 25 countries from September 2015 to December 2018; the final date of follow-up was December 5, 2018. Eligible patients were anthracycline-naive adults with unresectable locally advanced or metastatic STS, an Eastern Cooperative Oncology Group performance status of 0 to 1, and cardiac ejection fraction of 50% or greater. Patients were randomized 1:1 to receive doxorubicin, 75 mg/m2 (day 1), combined with olaratumab (n = 258), 20 mg/kg in cycle 1 and 15 mg/kg in subsequent cycles, or placebo (n = 251) on days 1 and 8 for up to 8 21-day cycles, followed by olaratumab/placebo monotherapy. Dual primary end points were overall survival with doxorubicin plus olaratumab vs doxorubicin plus placebo in total STS and leiomyosarcoma (LMS) populations. Among the 509 patients randomized (mean age, 56.9 years; 58.2% women; 46.0% with LMS), all were included in the primary analysis and had a median length of follow-up of 31 months. No statistically significant difference in overall survival was observed between the doxorubicin plus olaratumab group vs the doxorubicin plus placebo group in either population (total STS: hazard ratio, 1.05 [95% CI, 0.84-1.30], P = .69, median overall survival, 20.4 months vs 19.7 months; LMS: hazard ratio, 0.95 [95% CI, 0.69-1.31], P = .76, median overall survival, 21.6 months vs 21.9 months). Adverse events of grade 3 or greater reported in 15% or more of total patients with STS were neutropenia (46.3% vs 49.0%), leukopenia (23.3% vs 23.7%), and febrile neutropenia (17.5% vs 16.5%). In this phase 3 clinical trial of patients with advanced STS, treatment with doxorubicin plus olaratumab vs doxorubicin plus placebo resulted in no significant difference in overall survival. The findings did not confirm the overall survival benefit observed in the phase 2 trial. ClinicalTrials.gov Identifier: NCT02451943