Drought triggers and sustains overnight fires in North America

Overnight fires are emerging in North America with previously unknown drivers and implications. This notable phenomenon challenges the traditional understanding of the 'active day, quiet night' model of the diurnal fire cycle1-3 and current fire management practices4,5. Here we demonstrate that drought conditions promote overnight burning, which is a key mechanism fostering large active fires. We examined the hourly diurnal cycle of 23,557 fires and identified 1,095 overnight burning events (OBEs, each defined as a night when a fire burned through the night) in North America during 2017-2020 using geostationary satellite data and terrestrial fire records. A total of 99% of OBEs were associated with large fires (>1,000 ha) and at least one OBE was identified in 20% of these large fires. OBEs were early onset after ignition and OBE frequency was positively correlated with fire size. Although warming is weakening the climatological barrier to night-time fires6, we found that the main driver of recent OBEs in large fires was the accumulated fuel dryness and availability (that is, drought conditions), which tended to lead to consecutive OBEs in a single wildfire for several days and even weeks. Critically, we show that daytime drought indicators can predict whether an OBE will occur the following night, which could facilitate early detection and management of night-time fires. We also observed increases in fire weather conditions conducive to OBEs over recent decades, suggesting an accelerated disruption of the diurnal fire cycle.

Spatial planning of fire-agency stations as a function of wildfire likelihood in Thasos, Greece

Even though wildfires constitute a natural phenomenon, they may have severe implications with respect to the socioeconomic structure of the affected population and the ecological wealth of a territory, especially when they burn under high intensities. Timing of the initial attack is thus crucial to fire control in areas that fires are considered to be under high threat of burning. The aim of this paper is to investigate the combined use of simulation modeling and spatial optimization to assess the pre-positioning of fire-management resources on a small Greek island, Thasos, based on the current and desired fire agency capabilities, maximization of environmental protection, and rationalization of financial resources. The estimation of burn probability (BP) depicted specific areas of high fire hazard in the southern, central, and western part of the island, where essential preventive measures should be undertaken. Based on this result, BP was then used as a primary input for the assessment of optimal locations of fire operation agencies in order to achieve the maximal coverage under certain (already available) and minimum number of fire-fighting vehicles in different time windows. The results generated three differentiated optimal location schemes [8 available vehicles within either 10 (immediate response time) or 31 min (average response time) with the current fire resources; 19 and 2 required vehicles within 10 and 31 min, respectively, based on a minimum number of fire resources]. This type of information enables us to propose a relocation of the current fire agency in a southern town of the island. The flexibility and interaction of the models provide a framework for appropriate decision making under a set of political and financial constraints.

The Science of Firescapes: Achieving Fire-Resilient Communities

Wildland fire management has reached a crossroads. Current perspectives are not capable of answering interdisciplinary adaptation and mitigation challenges posed by increases in wildfire risk to human populations and the need to reintegrate fire as a vital landscape process. Fire science has been, and continues to be, performed in isolated “silos,” including institutions (e.g., agencies versus universities), organizational structures (e.g., federal agency mandates versus local and state procedures for responding to fire), and research foci (e.g., physical science, natural science, and social science). These silos tend to promote research, management, and policy that focus only on targeted aspects of the “wicked” wildfire problem. In this article, we provide guiding principles to bridge diverse fire science efforts to advance an integrated agenda of wildfire research that can help overcome disciplinary silos and provide insight on how to build fire-resilient communities.

Past, current and future fire frequency in the Canadian boreal forest: implications for sustainable forest management

Over the past decades, there has been an increasing interest in the development of forest management approaches that are based on an understanding of historical natural disturbance dynamics. The rationale for such an approach is that management to favor landscape compositions and stand structures similar to those of natural ecosystems should also maintain biological diversity and essential ecological functions. In fire-dominated landscapes, this approach is possible only if current and future fire frequencies are sufficiently low, comparing to pre-industrial fire frequency, that we can substitute fire by forest management. We address this question by comparing current and future fire frequency to historical reconstruction of fire frequency from studies realized in the Canadian boreal forest. Current and simulated future fire frequencies using 2 and 3 x CO2 scenarios are lower than the historical fire frequency for many sites, suggesting that forest management could potentially be used to recreate the forest age structure of fire-controlled pre-industrial landscapes. There are however, important limitations to the current even-age management.

An analysis of the daily radial activity of 7 boreal tree species, northwestern Quebec

In the 'Des Vieux Arbres' ecological reserve situated within northwestern Quebec, 40 band dendrometers were installed on 7 of the major boreal tree species. The late Spring-early Summer daily radial activity registered in 1997 was related to daily weather variables. For each tree species, the daily mean i) cumulative radial increment and ii) radial activity indexed series obtained by first-difference standardization were analyzed. The results indicate the existence of strong similarities among the 7 species. All showed strong synchronous fluctuations in radius during late winter and early spring. This period ended with a short but sharp increase in radial increments that marked the passage of water into the stem. This initial swelling, less obvious in Pinus species was followed by a prolonged period of little change in radial activity. Meteorological data indicated that air temperature was positively related to stem swelling during the late winter-early spring period. Both air and soil temperatures became negatively related to radial expansion once the passage of water has occurred in the stem. Starting in early June, all species registered a sustained increase in radial increments possibly associated with active cell division. After this, radial expansion was negatively related to air temperature and positively to rainfall.

Morning vs evening dosing with doxazosin in benign prostatic hyperplasia: efficacy and safety

Three hundred and fifty-three patients with symptomatic benign prostatic hyperplasia were randomized to doxazosin or placebo, with morning or evening dosing, to compare the effect of dosing time on the efficacy and safety of doxazosin treatment. After 24 weeks of treatment, the mean International Prostate Symptom Score had decreased by 6.8 units in the doxazosin group compared with 4.5 units in the placebo group (P=0.003). Improvements in Q(max) of 2.03 ml/s and 0.30 ml/s were seen for the doxazosin and the placebo groups, respectively (P<0.001). No differences in efficacy or safety between the morning- and evening-dosed subgroups were observed. Doxazosin was significantly more effective than placebo at improving symptoms of BPH and urinary flow rates at endpoint, and was well tolerated. The time of dosing did not appear to influence the efficacy or safety of doxazosin, suggesting that there is no need to restrict administration of doxazosin to the evening in BPH patients.

Prazosin in the treatment of prostatic obstruction. A placebo-controlled study

Eighty patients with prostatic obstruction were entered into a double-blind parallel study of prazosin versus placebo. There were 25 withdrawals or exclusions, leaving 55 patients for analysis. Mean maximum flow rates increased significantly more in patients treated with prazosin than in those treated with placebo (P less than 0.005), but there was no significant reduction in maximum voiding pressure. The mean number of voids, recorded on diary cards, was reduced from an initial 10.0/24 h by 2.1 in the final week, a significantly greater reduction than in the placebo group (P less than 0.01). However, there were no statistically significant changes in the filling cystometrograms. When patients were classified as responders or non-responders in terms of bladder filling, urine flow, bladder emptying, weekly average of voids/24 h and nocturia, the proportion of patients responding to prazosin was significantly greater in all categories except bladder filling and emptying. It was concluded that prazosin at a dose of 2 mg bd is a safe and effective treatment for prostatic obstruction and may be used in patients awaiting surgery and those who are unfit for operation.