Mapping carbon accumulation potential from global natural forest regrowth.

To constrain global warming, we must strongly curtail greenhouse gas emissions and capture excess atmospheric carbon dioxide1,2. Regrowing natural forests is a prominent strategy for capturing additional carbon3, but accurate assessments of its potential are limited by uncertainty and variability in carbon accumulation rates2,3. To assess why and where rates differ, here we compile 13,112 georeferenced measurements of carbon accumulation. Climatic factors explain variation in rates better than land-use history, so we combine the field measurements with 66 environmental covariate layers to create a global, one-kilometre-resolution map of potential aboveground carbon accumulation rates for the first 30 years of natural forest regrowth. This map shows over 100-fold variation in rates across the globe, and indicates that default rates from the Intergovernmental Panel on Climate Change (IPCC)4,5 may underestimate aboveground carbon accumulation rates by 32 per cent on average and do not capture eight-fold variation within ecozones. Conversely, we conclude that maximum climate mitigation potential from natural forest regrowth is 11 per cent lower than previously reported3 owing to the use of overly high rates for the location of potential new forest. Although our data compilation includes more studies and sites than previous efforts, our results depend on data availability, which is concentrated in ten countries, and data quality, which varies across studies. However, the plots cover most of the environmental conditions across the areas for which we predicted carbon accumulation rates (except for northern Africa and northeast Asia). We therefore provide a robust and globally consistent tool for assessing natural forest regrowth as a climate mitigation strategy.

Phosphorus concentrations in soil and subsurface water: a field study among cropland and riparian buffers.

Riparian buffers can be effective at removing phosphorus (P) in overland flow, but their influence on subsurface P loading is not well known. Phosphorus concentrations in the soil, soil solution, and shallow ground water of 16 paired cropland-buffer plots were characterized during 2004 and 2005. The sites were located at two private dairy farms in Central New York on silt and gravelly silt loams (Aeric Endoaqualfs, Fluvaquentic Endoaquepts, Fluvaquentic Eutrudepts, Glossaquic Hapludalfs, and Glossic Hapludalfs). It was hypothesized that P availability (sodium acetate extractable-P) and soil-landscape variability would affect P release to the soil solution and shallow ground water. Results showed that P availability tended to be greater in crop fields relative to paired buffer plots. Soil P was a good indicator of soil solution dissolved (<0.45 microm) molybdate-reactive P (DRP) concentrations among plots, but was not independently effective at predicting ground water DRP concentrations. Mean ground water DRP in corn fields ranged from < or =20 to 80 microg L(-1), with lower concentrations in hay and buffer plots. More imperfectly drained crop fields and buffers tended to have greater average DRP, particulate (> or =0.45 microm) reactive P (PRP), and dissolved unreactive P (DUP) concentrations in ground water. Soil organic matter and 50-cm depth soil solution DRP in buffers jointly explained 75% of the average buffer ground water DRP variability. Results suggest that buffers were relatively effective at reducing soil solution and shallow ground water DRP concentrations, but their impact on particulate and organic P in ground water was less clear.

Nitrogen dynamics among cropland and riparian buffers: soil-landscape influences.

Nitrate (NO3-) leaching to ground water poses water quality concerns in some settings. Riparian buffers have been advocated to reduce excess ground water NO3- concentrations. We characterized inorganic N in soil solution and shallow ground water for 16 paired cropland-riparian plots from 2003 to 2005. The sites were located at two private dairy farms in Central New York on silt and gravelly silt loam soils (Aeric Endoaqualfs, Fluvaquentic Endoaquepts, Fluvaquentic Eutrudepts, Glossaquic Hapludalfs, and Glossic Hapludalfs). It was hypothesized that cropland N inputs and soil-landscape variability would jointly affect NO3- leaching and transformations in ground water. Results showed that well and moderately well drained fields had consistently higher ground water NO3- compared to more imperfectly drained fields receiving comparable N inputs. Average 50-cm depth soil solution NO3- and ground water dissolved oxygen (DO) explained 64% of average cropland ground water NO3- variability. Cropland ground water with an average DO of <3 mg L(-1) tended to have <4 mg L(-1) of NO3- with a water table depth (WTD) of

Methods of Soil Resampling to Monitor Changes in the Chemical Concentrations of Forest Soils.

Recent soils research has shown that important chemical soil characteristics can change in less than a decade, often the result of broad environmental changes. Repeated sampling to monitor these changes in forest soils is a relatively new practice that is not well documented in the literature and has only recently been broadly embraced by the scientific community. The objective of this protocol is therefore to synthesize the latest information on methods of soil resampling in a format that can be used to design and implement a soil monitoring program. Successful monitoring of forest soils requires that a study unit be defined within an area of forested land that can be characterized with replicate sampling locations. A resampling interval of 5 years is recommended, but if monitoring is done to evaluate a specific environmental driver, the rate of change expected in that driver should be taken into consideration. Here, we show that the sampling of the profile can be done by horizon where boundaries can be clearly identified and horizons are sufficiently thick to remove soil without contamination from horizons above or below. Otherwise, sampling can be done by depth interval. Archiving of sample for future reanalysis is a key step in avoiding analytical bias and providing the opportunity for additional analyses as new questions arise.

Cystic metastasis versus branchial cleft carcinoma: a diagnostic challenge.

OBJECTIVES: There is controversy regarding the existence of branchial cleft carcinomas. The objectives are to familiarize the clinician with the presentation and treatment of cystic metastases from head and neck primary sites and differentiate these from primary branchial cleft cyst carcinomas. STUDY DESIGN: Retrospective case study and literature review. METHODS: Published reports of branchial cleft carcinomas were reviewed in conjunction with a unique case presenting at the University of Texas Medical Branch (Galveston, TX). RESULTS: Most cases of branchial cleft carcinomas are probably cystic metastases from head and neck primary sites. Cutaneous involvement with primary branchial cleft carcinomas is rare but may occur in recurrent lesions. CONCLUSIONS: The diagnosis of a primary branchial cleft cyst carcinoma requires the fulfillment of strict criteria. Cystic metastases from head and neck primaries can mimic branchial cleft carcinomas histologically. Correct diagnosis is important so that appropriate surgical and radiotherapeutic treatment can be delivered.

Smoking in chronic rhinosinusitis: a predictor of poor long-term outcome after endoscopic sinus surgery.

OBJECTIVE: This study was designed to determine whether smoking patients have poorer outcomes after endoscopic sinus surgery (ESS) based on a reliable validated rhinosinusitis-specific quality-of-life outcomes test. STUDY DESIGN: Retrospective chart and computed tomography (CT) review with telephone and letter questionnaire. METHODS: Charts of 230 adult patients undergoing ESS for chronic rhinosinusitis between January 1995 and December 1998 were reviewed. Each participating patient completed a detailed questionnaire, including the Sino-Nasal Outcome Test-16 (SNOT-16), at an average of 52 months after surgery. Preoperative CT scans were reviewed and the findings used to stage the patients' conditions. Multivariate analysis was used to assess these data. RESULTS: Eighty-two patients completed the questionnaire, with 26 who smoked at the time of surgery and continued to smoke at the time of answering the questionnaire (Smokers). Average SNOT-16 score in Smokers was 27.5, versus 18.2 in those who did not smoke at the time of surgery (Non-Smokers). There was a statistically significant correlation between elevated SNOT-16 scores and smoking (P <.001) and antibiotic use within the past year (P <.001). There was an association between high SNOT-16 scores and both prior smoking and passive smoke exposure that did not reach statistical significance (P =.055 and P =.267, respectively). CT staging scores and prior ESS were not statistically correlated with SNOT-16 scores. CONCLUSIONS: Smoking is associated with statistically worse outcomes after ESS based on average SNOT-16 scores. Although no investigator has proved that the effects of smoking on sinonasal health are reversible, we counsel smoking patients considering ESS about the desirability of smoking cessation (for this and many health reasons), and the possibility of a poorer postsurgery outcome should they continue smoking.

Evaluation of the internal auditory canal with virtual endoscopy.

OBJECTIVE: Three-dimensional imaging can improve the understanding and comprehension of complex anatomy. Recent advances in software development allow the construction of a virtual endoscopic view of anatomic structures. This report applies virtual endoscopic capabilities to imaging of the internal auditory canal. STUDY DESIGN, SETTING, AND PATIENTS: We conducted a retrospective case review at a tertiary referral center of patients with abnormal internal auditory canal anatomy on computed tomography. INTERVENTIONS: Computed tomography images were obtained using conventional clinical algorithms involving multiple, 1-mm-thick slices through the temporal bone. Three-dimensional reconstructions were made using General Electric Advantage Windows Navigator software. The virtual endoscopic image-processing algorithm used selected image intensity threshold levels to visualize internal auditory canal anatomy from an endoscopic perspective. RESULTS: Eleven cases of abnormalities of the internal auditory canal were retrospectively identified. Clinical applications using the virtual endoscopic images are presented. The virtual endoscopic images supported prior clinical decision making in 6 of the 11 cases evaluated. CONCLUSION: This technique shows promise for the diagnosis, surgical planning, and teaching of temporal bone anatomy. Usefulness is dependent on acquisition parameters and clinical indications for examination.