Experimental warming altered plant functional traits and their coordination in a permafrost ecosystem.

Knowledge about changes in plant functional traits is valuable for the mechanistic understanding of warming effects on ecosystem functions. However, observations have tended to focus on aboveground plant traits, and there is little information about changes in belowground plant traits or the coordination of above- and belowground traits under climate warming, particularly in permafrost ecosystems. Based on a 7-yr field warming experiment, we measured 26 above- and belowground plant traits of four dominant species, and explored community functional composition and trait networks in response to experimental warming in a permafrost ecosystem on the Tibetan Plateau. Experimental warming shifted community-level functional traits toward more acquisitive values, with earlier green-up, greater plant height, larger leaves, higher photosynthetic resource-use efficiency, thinner roots, and greater specific root length and root nutrient concentrations. However, warming had a negligible effect in terms of functional diversity. In addition, warming shifted hub traits which have the highest centrality in the network from specific root area to leaf area. These results demonstrate that above- and belowground traits exhibit consistent adaptive strategies, with more acquisitive traits in warmer environments. Such changes could provide an adaptive advantage for plants in response to environmental change.

Characteristics of methane emissions from alpine thermokarst lakes on the Tibetan Plateau.

Understanding methane (CH4) emission from thermokarst lakes is crucial for predicting the impacts of abrupt thaw on the permafrost carbon-climate feedback. However, observational evidence, especially from high-altitude permafrost regions, is still scarce. Here, by combining field surveys, radio- and stable-carbon isotopic analyses, and metagenomic sequencing, we present multiple characteristics of CH4 emissions from 120 thermokarst lakes in 30 clusters along a 1100 km transect on the Tibetan Plateau. We find that thermokarst lakes have high CH4 emissions during the ice-free period (13.4 ± 1.5 mmol m-2 d-1; mean ± standard error) across this alpine permafrost region. Ebullition constitutes 84% of CH4 emissions, which are fueled primarily by young carbon decomposition through the hydrogenotrophic pathway. The relative abundances of methanogenic genes correspond to the observed CH4 fluxes. Overall, multiple parameters obtained in this study provide benchmarks for better predicting the strength of permafrost carbon-climate feedback in high-altitude permafrost regions.

Microbial nitrogen and phosphorus co-limitation across permafrost region.

The status of plant and microbial nutrient limitation have profound impacts on ecosystem carbon cycle in permafrost areas, which store large amounts of carbon and experience pronounced climatic warming. Despite the long-term standing paradigm assumes that cold ecosystems primarily have nitrogen deficiency, large-scale empirical tests of microbial nutrient limitation are lacking. Here we assessed the potential microbial nutrient limitation across the Tibetan alpine permafrost region, using the combination of enzymatic and elemental stoichiometry, genes abundance and fertilization method. In contrast with the traditional view, the four independent approaches congruently detected widespread microbial nitrogen and phosphorus co-limitation in both the surface soil and deep permafrost deposits, with stronger limitation in the topsoil. Further analysis revealed that soil resources stoichiometry and microbial community composition were the two best predictors of the magnitude of microbial nutrient limitation. High ratio of available soil carbon to nutrient and low fungal/bacterial ratio corresponded to strong microbial nutrient limitation. These findings suggest that warming-induced enhancement in soil nutrient availability could stimulate microbial activity, and probably amplify soil carbon losses from permafrost areas.

Holmium laser enucleation of the prostate: a modified enucleation technique and initial results.

PURPOSE: Although holmium laser enucleation of the prostate has been proven to be an excellent technique for the treatment of benign prostatic hyperplasia, it has not been widely applied due to technical difficulties and longer operative time. We modified the current technique of enucleation and present our initial experience. MATERIALS AND METHODS: A total of 189 patients with benign prostatic hyperplasia underwent prostatectomy with our modified technique for holmium laser enucleation of the prostate. Intraoperative and postoperative data were prospectively collected. For followup International Prostate Symptom Score, quality of life, maximal flow rate and post-void residual urine were recorded. RESULTS: Mean±SD preoperative prostate volume was 78.1±24.3 cc and 60.9±39.2 gm tissue were enucleated. Mean operative and enucleation times were 54.7±21.1 and 36.5±16.3 minutes, respectively. Mean serum hemoglobin decrease was 0.98±0.72 gm/dl. Mean catheter time was 1.2±0.5 days and mean postoperative hospital stay was 4.9±3.4 days. Serious complications were not observed. Three patients complained of transient stress incontinence which resolved within 3 months. Significant improvement occurred in International Prostate Symptom Score, quality of life, maximal flow rate and post-void residual urine volume at 3 and 6-month followup compared with the preoperative baseline. CONCLUSIONS: The modified holmium laser enucleation of the prostate technique is effective and safe when treating benign prostatic hyperplasia.