Tropical cyclones moving into boreal forests: Relationships between disturbance areas and environmental drivers.

Tropical cyclones (TCs) are common disturbance agents in tropical and subtropical latitudes. With global warming, TCs began to move to northern latitudes, with devastating effects on boreal forests. However, it remains unclear where and when these extraordinary events occur and how they affect forest structure and ecosystem functioning. Hence knowing which geomorphological features, landforms, and forest types are most susceptible to severe wind disturbance is vital to better predict the future impacts of intensifying tropical cyclones on boreal forests. In October 2015, catastrophic TC Dujuan hit the island of Sakhalin in the Russian Far East. With a wind speed of 63 m·s-1, it became the strongest wind recorded in Sakhalin, damaging >42,000 ha of native forests with different levels of severity. We used high-resolution RGB satellite images, DEM-derived geomorphological patterns, and the U-Net-like convolutional neural network to quantify the damaged area in specific landform, forest type, and windthrow patch size categories. We found that large gaps (>1 ha) represent >40 % of the damaged area while small gaps (<0.1 ha) only 20 %. The recorded canopy gaps are very large for the southern boreal forest. We found that the aspect (slope exposure) is the most important in explaining the damaged area, followed by canopy closure and landform type. Closed-canopy coniferous forests on steep, west-facing slopes (typical of convex reliefs such as ridges, spurs, and peaks) are at a much higher risk of being disturbed by TCs than open-canopy mountain birch forests or coniferous forests and broadleaved riparian forests in concave reliefs such as valley bottoms. We suggest that the projected ongoing poleward migration of TCs will lead to an unprecedentedly large area of disturbed forest, which results in complex changes in forest dynamics and ecosystem functioning. Our findings are crucial for the development of mitigation and adaptation strategies under future changes in TC activity.

Variations in tuberculosis prevalence, Russian Federation: a multivariate approach.

OBJECTIVE: To analyse the epidemiological trends of tuberculosis in the Siberian and Far Eastern federal districts, the areas with the highest disease burden in the Russian Federation. METHODS: We applied principal coordinate analysis to study a total of 68 relevant variables on tuberculosis epidemiology, prevention and control. Data on these variables were collected over 2003-2016 in all 21 regions of the Siberian federal district and Far Eastern federal district (total population: 25.5 million) through the federal and departmental reporting system. We identified the regions with a favourable or unfavourable tuberculosis epidemiological profile and ranked them as low or high priority for specific interventions. FINDINGS: The median number of tuberculosis notifications in the regions was 123.3 per 100 000 population (range: 54.5-265.7) in 2003, decreasing to 82.3 per 100 000 (range: 52.9-178.3) in 2016. We found large variations in the tuberculosis epidemiological profile across different regions. The principal coordinate analysis revealed that three aggregated indicators accounted for 55% of the variation. The first coordinate corresponded to tuberculosis prevalence and case notifications in the regions; the second to the severity of the disease among patients; and the third to the percentage of multidrug-resistant tuberculosis among tuberculosis patients. The regions where intervention was most urgently needed were Chukotka Autonomous Okrug, Jewish Autonomous Oblast and Tyva Republic. CONCLUSION: The variability in tuberculosis epidemiology across regions was likely due to differences in the quality of antituberculosis services. Precision in defining necessary interventions, as determined through the principal coordinate analysis approach, can guide focused tuberculosis control efforts.

Poleward migration of the destructive effects of tropical cyclones during the 20th century.

Determination of long-term tropical cyclone (TC) variability is of enormous importance to society; however, changes in TC activity are poorly understood owing to discrepancies among various datasets and limited span of instrumental records. While the increasing intensity and frequency of TCs have been previously documented on a long-term scale using various proxy records, determination of their poleward migration has been based mostly on short-term instrumental data. Here we present a unique tree-ring-based approach for determination of long-term variability in TC activity via forest disturbance rates in northeast Asia (33-45°N). Our results indicate significant long-term changes in TC activity, with increased rates of disturbances in the northern latitudes over the past century. The disturbance frequency was stable over time in the southern latitudes, however. Our findings of increasing disturbance frequency in the areas formerly situated at the edge of TC activity provide evidence supporting the broad relevance of poleward migration of TCs. Our results significantly enhance our understanding of the effects of climate change on TCs and emphasize the need for determination of long-term variation of past TC activity to improve future TC projections.