Biological Productivity of the Post-Fire Larch Forests in the Mountain Regions of Krasnoyarsk Krai

Abstract

Peculiarities of the compositionally pure larch stand formation following forest fires have been studied in the northern (Evenkia, middle course of the Nizhnyaya Tunguska River, 64°03′ N, 101°10′ E) and southern (Yermakovsky District, 52°23′ N, 93°33 ′ E) regions of Krasnoyarsk Krai. The structure, growth, and biological productivity of the forest restoration successions have been analyzed based on the materials from the sample plots. The highest phytomass value (in terms of total productivity) in larch stands is 1055.5 t abs. dry substances/ha at the age of 93 years. The structural ratio of the forest stands phytomass fractions naturally changes with an increase in their average age and density. An increase in the average age of a stand is associated with an increase in its above-ground and root phytomasses. At the same time, the relative proportion of the crown wood mass and needle mass in the total above-ground phytomass of a stand decreases. In 38-year-old larch forests, the proportion of crown mass is 18% and the share of stems is 82%. In 60-year-old forest stands, the total biomass of the crown wood and needles accounts for 14%, and the other 86% accounts for the stem weight. In the 93-year-old larch forest, the proportion of stem phytomass increases to 89%, and the proportion of combined crown wood and needles biomasses fall up to a minimum value of 11%. The maximum growth potential of the 56-year-old larch stands, according to the current increase in phytomass (in terms of total productivity), is realized at about 14.69 t abs. dry substances/ha per year. The young and middle-aged larch forests formed on the burnt areas have higher rates of growth and phytomass accumulation; in terms of the amount of fixed atmospheric carbon, they exceed the mature and overmature stands by more than two times.