TY - JOUR AU - Sydorenko, S. H. PY - 2020/06/25 Y2 - 2024/03/28 TI - Fire resistance and post-pyrogenic mortality of pine forests in the left-bank part of Kharkiv Region at different levels of fire hazard JF - Forestry and Forest Melioration JA - Forest. and Forest Melior. VL - 0 IS - 136 SE - ECOLOGY AND MONITORING DO - 10.33220/1026-3365.136.2020.134 UR - http://forestry-forestmelioration.org.ua/index.php/journal/article/view/266 SP - 134-141 AB - <p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><strong>Introduction</strong></span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">The impact of forest fires on pine stands health and the rate of post-fire tree mortality depends on a number of factors. They are a type of fire, its intensity and duration, a predominant type of damage, and characteristics of the damaged stand. The secondary post-fire factors include trees infestation by beetles and diseases, health condition of the stand before the fire and the level of its weakening as well as impact of droughts.</span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><strong>Materials and Methods</strong></span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">Data from 58 sample plots (SP) were used to assess post-fire tree mortality. The stands on SP varied in age (43–95 years), their mensuration characteristics (diameter: 17–51 cm, height: 18.0–25.7 m, relative density of stocking: 0.5–1.0), fire damage intensity (average bark char height ranged from 0.4 to 4.9 m), a form of fire (running and slow surface fires), a year (2005–2018) and season of fire. SP were laid out mainly in the forests of the Forest-Steppe part of Kharkiv Region, grown in the fresh infertile and fairly infertile pine sites. A one-year post-fire period was used in the study.</span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">To assess the fire hazard level, a complex index of fire hazard</span></span></span></span> <span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">by Nesterov (Nesterov 1945) was calculated. The correlation, regression and multiple regression analyses were performed according to generally accepted methods (Atramentova &amp; Utevska 2007).</span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><strong>Results </strong></span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">Fires are one of the most dangerous destabilizing factors for forests. On determining specific features of the post-pyrogenic development of pine forests, it is possible to mitigate negative consequences caused by forest fires and assist in the management of forests damaged by surface fires. It was revealed that the health condition of the stands depended on the level of the fire hazard at the time of the fire, and worsened as fire hazard increased (</span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><em>r</em></span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"> = 0.71; </span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><em>p</em></span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"> = 0.05). With a high fire hazard (estimated by Nesterov methodology), the fire intensity (intensity of heat release during a fire) and amount of burnt forest fuel also increase. It has been established that with the fire danger score from 1,500 to 3,000, the categories of stand health varied from II,0 to III,9; the mortality rate reached 20%. With a further increase in the fire hazard up to more than 5,000, the health condition index of the damaged stands a year after the fire was III,5–V,0. It was found that the flame height and the bark char height on the trunks do not depend reliably on the fire hazard level by weather conditions. The approaches to predicting post-fire mortality at the stand level are improved taking into account fire hazard characteristics during a fire season, as well as the level of damage to trees in a pine stand and its morphometric characteristics.</span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><strong>Conclusions</strong></span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">A correlation between surface fire consequences (a rate of post-fire trees mortality) and the fire hazard index by weather conditions was found. It is explained by the fact that the rate of drying of surface forest fuel depends on the fire hazard index by Nesterov. With higher values of </span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">fire hazard</span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">, the intensity of heat release during a forest fire and the level of forest litter burning increase. Thus, for </span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">complex index of fire hazard</span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"> from 1,500 to 3,000, a health condition index varied from II,0 to III,9. At that, the tree mortality reached 20% of total number of trees. With a further increase in the </span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">index</span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"> of fire danger up to more than 5,000 points, the health condition index of pine stands a year after the fire varied from III,5 to V,0.</span></span></span></span></p><p class="western" align="justify"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US">It was found that the height of the bark char on the tree trunks does not significantly depend on the fire danger level.</span></span></span></span></p><p class="western"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="ru-RU"><strong>2</strong></span></span></span><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><strong> Figs., 2 Tables, </strong></span></span></span><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="ru-RU"><strong>16</strong></span></span></span><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><strong> Refs.</strong></span></span></span></p><p class="western"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"><strong>Key words:</strong></span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span lang="en-US"> postfire mortality models, fire resistance, fire hazard, consequences of forest fires.</span></span></span></span></p> ER -