Climate Change Alters Seedling Emergence and Establishment in an Old-Field Ecosystem

Background: Ecological succession drives large-scale changes in ecosystem composition over time, but the mechanisms whereby climatic change might alter succession remain unresolved. Here, we asked if the effects of atmospheric and climatic change would alter tree seedling emergence and establishment in an old-field ecosystem, recognizing that small shifts in rates of seedling emergence and establishment of different species may have long-term repercussions on the transition of fields to forests in the future. Methodology/Principal Findings: We introduced seeds from three early successional tree species into constructed old-field plant communities that had been subjected for 4 years to altered temperature, precipitation, and atmospheric CO 2 regimes in an experimental facility. Our experiment revealed that different combinations of atmospheric CO2 concentration, air temperature, and soil moisture altered seedling emergence and establishment. Treatments directly and indirectly affected soil moisture, which was the best predictor of seedling establishment, though treatment effects differed among species. Conclusions: The observed impacts, coupled with variations in the timing of seed arrival, are demonstrated as predictors o

Experimental climate change impacts on ecosystem attributes.

<p>Soil moisture and temperature treatments became more pronounced and foliar cover of the old-field plant community increased as maple seedling emerged and established later in the spring. The first bar represents when pine and sweetgum seedlings emerged, while the second bar represents when maple seedlings emerged.</p

Results of an ANOVA examining the direct and interactive effects of changes in species, [CO₂], air temperature, and soil moisture on seedling emergence, mortality, and establishment (n = 3).

<p>Bold numbers indicated statistical significance (P<0.05).</p

Results of a multiple regression examining the effects of soil temperature, soil moisture, [CO₂], and plant cover on seedling emergence and establishment.

<p>Results of a multiple regression examining the effects of soil temperature, soil moisture, [CO₂], and plant cover on seedling emergence and establishment.</p

Results of an ANOVA examining the direct and interactive effects of changes in [CO₂], air temperature, and soil moisture on silver maple, sweetgum, and loblolly pine seedling emergence and establishment (n = 3).

<p>Bold numbers indicated statistical significance (P<0.05).</p

Seedling emergence.

<p>Silver maple seedlings, with a later, spring seed arrival, emerged one month after loblolly pine and sweetgum seedlings that have an earlier, fall seed arrival.</p

Does routine postoperative contrast radiography improve outcomes for patients with perforated peptic ulcer? A multicenter retrospective cohort study.

BACKGROUND: Perforated peptic ulcer is a morbid emergency general surgery condition. Best practices for postoperative care remain undefined. Surgical dogma preaches practices such as peritoneal drain placement, prolonged nil per os, and routine postoperative enteral contrast imaging despite a lack of evidence. We aimed to evaluate the role of postoperative enteral contrast imaging in postoperative perforated peptic ulcer care. Our primary objective was to assess effects of routine postoperative enteral contrast imaging on early detection of clinically significant leaks. METHODS: We conducted a multicenter retrospective cohort study of patients who underwent repair of perforated peptic ulcer between July 2016 and June 2018. We compared outcomes between those who underwent routine postoperative enteral contrast imaging and those who did not. RESULTS: Our analysis included 95 patients who underwent primary/omental patch repair. The mean age was 60 years, and 54% were male. Thirteen (14%) had a leak. Eighty percent of patients had a drain placed. Nine patients had leaks diagnosed based on bilious drain output without routine postoperative enteral contrast imaging. Use of routine postoperative enteral contrast imaging varied significantly between institutions (30%-87%). Two late leaks after initial normal postoperative enteral contrast imaging were confirmed by imaging after a clinical change triggered the second study. Two patients had contained leaks identified by routine postoperative enteral contrast imaging but remained clinically well. Duration of hospital stay was longer in those who received routine postoperative enteral contrast imaging (12 vs 6 days, median; P = .000). CONCLUSION: Routine postoperative enteral contrast imaging after perforated peptic ulcer repair likely does not improve the detection of clinically significant leaks and is associated with increased duration of hospital stay