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

Peculiarities of the compositionally pure larch stands formation following forest fires were studied in the northern (Evenkia, middle course of the Nizhnyaya Tunguska river, geographic coordinates 64°03′ N 101°10′ E) and southern (Ermakovskiy district, geographic coordinates – 52°23′ N, 93°33′ E) areas of Krasnoyarsk Krai. The structure, growth and biological productivity of the forest restoration successions were analyzed based on the materials from the sample plots. The highest value of phytomass (in terms of total productivity) in larch stands registered was 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. With an increase in the average age of a stand, its above-ground and root phytomasses increase; at the same time, the relative share of crown and needle wood mass in the total above-ground phytomass of a stand decreases. In 38-year-old larch forests, the share of crown mass is 18%, and the share of stems is 82%. In 60-year-old forest stands, crown wood with needles accounts for 14%, and the rest 86% are stem weight. In the 93-year-old larch forest, the proportion of stem phytomass increases to 89%, and the proportion of crown wood with needles falls up to a minimum share of 11%. The maximum growth potential of the 56-year old larch stands, according to the current increase in phyomass (in terms of total productivity), is realised 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.